JP2003079183A - Synchronous motor step-out detection device, synchronous motor step-out detection method, hermetic compressor drive device, and fan motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous motor out-of-synchronization detection device capable of accurately detecting out-of-synchronization of a synchronous motor by a simplified out-of-synchronization detection process. SOLUTION: In an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, a current detecting means for detecting a current flowing in the synchronous motor, and a current signal obtained by the current detecting means, Dq coordinate conversion means for performing coordinate conversion into an excitation current component (d-axis current) and a torque current component (q-axis current), and an AC component of the dq-axis current obtained by the dq coordinate conversion means. A step-out detecting step-out by comparing at least one of the dq-axis current AC component obtained by the current AC component detecting means and the step-out level signal arbitrarily set; And a detecting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor out-of-step detecting device and a synchronous motor out-of-step detecting method for driving a synchronous motor without using a position sensor for detecting a rotor position.

[0002]

2. Description of the Related Art FIG. 9 is a diagram showing a configuration of a general conventional inverter device. In the figure, 1 is a DC power supply unit, 2
Is an inverter device, 3 is a plurality of switching elements, 3a is a U-phase upper switching element, 3b is a V-phase upper switching element, 3c is a W-phase upper switching element,
3d is a U-phase lower switching element, 3e is a V-phase lower switching element, and 3f is a W-phase lower switching element. 4 is a plurality of freewheeling diodes connected in parallel with the plurality of switching elements 3 and 5 is a plurality of switching elements 3
An inverter main circuit including a plurality of free wheeling diodes 4 and a DC brushless motor.

Reference numeral 7a is a current detecting means for detecting a one-phase current of the current flowing into the DC brushless motor 6, 7b is a current detecting means for detecting a current of a phase different from the current detecting means 7a, and 8 is a current detecting means 7a. , 7b is an inverter control means for controlling on / off of the switching element 3 in the inverter main circuit 5 based on the current value detected.

Reference numeral 9 is a PWM signal generating means for generating a PWM signal for turning on / off the switching element 3 based on the output voltage command value obtained in the inverter control means 8, and 10 is detected by the current detecting means 7a, 7b. Was done 2
Phase current calculating means for obtaining the current value of the three phases from the current value for the phase, 11 is a three-phase two-phase conversion for converting the current value of the three phases obtained by the phase current calculating means into the current value of the dq coordinate system. means,
Reference numeral 12 is a voltage command value calculating means for obtaining an output voltage command value of the dq coordinate system for driving the DC brushless motor based on the dq coordinate system current value obtained by the three-phase / two-phase converting means 11. Is an output voltage vector calculating means for obtaining an output voltage vector based on the output voltage command value of the dq coordinate system obtained by the voltage instruction value calculating means 12, and 14 is a DC voltage detecting means for detecting the DC voltage of the DC power supply 1. , 70 are overcurrent detecting means for detecting an overcurrent state of the phase current.

The operation of the inverter device and the DC brushless motor configured as described above will be described with reference to FIG. In the figure, the inverter device 2 detects currents of two phases out of the phase currents flowing into the DC brushless motor 6 by the current detecting means 7a and 7b. The inverter control means 8 uses the detected two-phase currents, for example, the U-phase current Iu and the V-phase current Iv, to output the voltage value and the voltage phase output from the inverter main circuit 5 for driving the DC brushless motor 6. The output voltage command value of is calculated and the PWM signal for ON / OFF control of the switching element 3 in the inverter main circuit 5 is output.

The inverter control means 8 outputs a PWM signal by the operation described below. The phase currents Iu, Iv detected by the current detecting means 7a, 7b are used by the phase current calculating means 10 to generate phase currents Iu, Iv, Iw for three phases.
Then, the phase current Iu for three phases is obtained by the three-phase / two-phase conversion means,
Iv and Iw are converted into currents Id and Iq in the dq coordinate system. The voltage command value calculation means 12 determines the current I of the dq coordinate system.
Output voltage command value Vd in dq coordinate system from d and Iq
^* , Vq ^* are calculated. The output voltage vector calculation means 13 calculates the output voltage vector Vx ^* from the output voltage command values Vd ^* and Vq ^{* of the} dq coordinate system. PWM
The signal generating means 9 obtains and outputs a PWM signal for controlling ON / OFF of the switching element 3 from the DC voltage Vdc obtained from the DC voltage detecting means 14 and the output voltage vector Vx ^* .

P output by the PWM signal generating means 9
The switching element 3 in the inverter main circuit 5 is turned on / off by the WM signal. Power is supplied from the inverter main circuit 5 to the DC brushless motor 6 by the ON / OFF operation of the switching element 3, and the DC brushless motor 6 is driven.

Here, the step-out detection in the above-mentioned conventional inverter device is carried out as follows. When the DC brushless motor 6 is out of step, the peak level of the phase current is higher than that in the synchronous operation, and step out is detected from this phenomenon. For example, the overcurrent detection means 70 compares the phase current value and the overcurrent level, and if the phase current exceeds the overcurrent level, it is determined as an overcurrent abnormality, and the out-of-step detection is performed by the overcurrent abnormality. Here, the overcurrent detection means 70 is composed of hardware or software.

Another example of a conventional step-out detection device for a synchronous motor is disclosed in Japanese Patent Laid-Open No. 11-18499. In the step-out detection device for a synchronous motor disclosed in Japanese Patent Application Laid-Open No. 11-18499, a γ-δ axis set to rotate at an estimated speed ωr is formed on the rotor in the controller, and Error θe from the d-q axes of This γ
−γ-axis induced voltage as a function of θe generated on the −δ axis, and δ
An example is described in which a state estimator that estimates the shaft induced voltage is configured and two out-of-range values are sequentially compared to detect out-of-step of the synchronous motor.

Further, another example of a conventional step-out detection device for a synchronous motor is disclosed in Japanese Patent Laid-Open No. 2001-25282. In the step-out detection device for a synchronous motor disclosed in Japanese Patent Laid-Open No. 2001-25282, an example of detecting step-out by comparing the cycle of the voltage output from the inverter device with the cycle of the current flowing in the sensorless brushless motor is disclosed. I am doing it. Further, an example is disclosed in which the step-out is detected by comparing the d-axis current which is the exciting current component and the step-out detection level.

[0011]

The conventional step-out detecting device for a synchronous motor is constructed as described above, and it is difficult to detect the step-out with high accuracy because the step-out state is detected from the phenomenon of overcurrent. there were. Even if the synchronous operation is continued without step out, the current may increase due to load increase or speed deceleration, resulting in over current. It was difficult to separate.
The overcurrent level used for overcurrent detection is a value set by the demagnetization resistance of the magnet used in the rotor of the DC brushless motor and the level of the limit current of the element used in the inverter device, and is used for out-of-step detection. It was difficult to set the detection level independently.

Further, depending on the combination of the inverter device and the DC brushless motor, the current at the time of step-out may be smaller than the current in the synchronous state, and thus detection by overcurrent may be impossible.

When the step-out state continues as described above, there is a problem that vibration and noise of the rotor of the electric motor occur. In addition, the device may be broken due to the vibration of the electric motor. Further, there is a problem that a current flowing through the synchronous motor becomes large and a semiconductor element or the like used in the inverter device is broken.

Further, in the step-out detecting device for a synchronous motor disclosed in Japanese Patent Laid-Open No. 11-18499, means for estimating the induced voltage of the motor is required for detecting the step-out, so that calculation by a microcomputer or the like is required. This will increase the processing load.

Further, in the step-out detecting device for a synchronous motor disclosed in Japanese Patent Laid-Open No. 2001-25282, step-out is performed by comparing the cycle of the voltage output from the inverter device with the cycle of the current flowing in the sensorless brushless motor. In order to detect, the voltage cycle output by the inverter device at the time of step out,
Step-out detection is impossible in a state where there is no difference in the cycle of the current flowing through the synchronous motor. Further, in the means for detecting the out-of-step by comparing the d-axis current which is the exciting current component and the out-of-step detection level, the exciting current changes depending on the conditions of the rotation speed and the load torque. Must be set to, which complicates the setting.

The present invention has been made to solve the above problems, and is a step-out detection device for a synchronous motor capable of accurately detecting a step-out of the synchronous motor with a simplified step-out detection processing. Another object of the present invention is to provide a step-out detection method for a synchronous motor. Another object of the present invention is to provide a drive device for a hermetic compressor and a drive device for a fan motor equipped with the step-out detection device for a synchronous motor as described above.

[0017]

A step-out detecting device for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position. Current detecting means for detecting the current, dq coordinate converting means for converting the current signal obtained by the current detecting means into an exciting current component (d-axis current) and a torque current component (q-axis current), and d-q coordinate converting means. Arbitrarily set to at least one of the current alternating current component detecting means for obtaining the alternating current component of the dq axis current obtained by the q coordinate converting means and the dq axis current alternating current component obtained by the current alternating current component detecting means. And a step-out detecting means for detecting the step-out by comparing the step-out level signal thus generated.

The step-out detection device for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position,
Current detecting means for detecting a current flowing through the synchronous motor, and a current signal obtained by the current detecting means are used as an exciting current component (d).
(Axis current) and torque current component (q-axis current) in terms of coordinate conversion means, and current-AC component detection means for obtaining the AC component of the d-q-axis current obtained by the dq coordinate conversion means. And dq obtained by the current and AC component detection means
AC component averaging means for averaging the effective value or absolute value of the axial current AC component and averaging the dq axis current AC component, and dq axis current obtained by the AC component averaging means Step-out detection means for detecting step-out by comparing at least one of the averaged values of the AC components with an arbitrarily set step-out level signal is provided.

The step-out detecting device for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position,
Current detecting means for detecting a current flowing through the synchronous motor, and a current signal obtained by the current detecting means are used as an exciting current component (d).
(Axis current) and torque current component (q-axis current) in the dq coordinate conversion means, and the dq coordinate current and dq coordinate current command value obtained by the dq coordinate conversion means. A current error calculating means for obtaining an error, a current error crossing component detecting means for detecting an AC component of the dq axis current error obtained by the current error calculating means, and a dq obtained by the current error AC component detecting means. Step-out detection means for detecting step-out by comparing at least one of the axial current error AC components with a step-out level signal set arbitrarily.

Further, the step-out detection device for a synchronous motor according to the present invention is characterized by detecting only a specific frequency component when detecting the AC component from the dq coordinate system current.

Further, the step-out detection device for a synchronous motor according to the present invention is characterized in that the specific frequency component has a frequency twice the frequency of the voltage output from the inverter device.

Further, the step-out detecting device for the synchronous motor according to the present invention detects the AC component of the dq axis current error,
The feature is that only a specific frequency component is detected.

The step-out detection device for a synchronous motor according to the present invention is characterized in that the step-out detection level compared with the average value of the q-axis current AC component is about 200% of the rated current of the synchronous motor. To do.

Further, the step-out detecting device for a synchronous motor according to the present invention, when step-out detection becomes difficult at low speed rotation,
Immediately after startup, the system is characterized by accelerating to the steady-state operating speed to detect out-of-step.

Further, the step-out detecting device for a synchronous motor according to the present invention detects a step-out in a process other than the acceleration / deceleration process when there is a possibility that an erroneous detection of the step-out detection may occur when the synchronous motor is accelerated or decelerated. It is characterized by performing processing.

The step-out detection device for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position,
The current detection means for detecting the current flowing through the synchronous motor, the output voltage command calculation means for obtaining the output voltage command value to be applied to the synchronous motor from the current signal obtained by the current detection means, and the output voltage command calculation means Output voltage vector calculation means for obtaining an output voltage vector based on the output voltage command value; output voltage abnormality detection means for comparing the magnitude of the output voltage vector obtained by the output voltage vector calculation means with a step-out detection level; Step-out detection means for detecting step-out from the comparison result obtained by the voltage abnormality detection means,
It is characterized by having.

The step-out detection method for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting the rotor position,
A current detection step of detecting a current flowing through the synchronous motor, and a dq coordinate conversion for converting the current signal obtained in the current detection step into an excitation current component (d-axis current) and a torque current component (q-axis current). At least one of the step, the current-AC component detecting step for obtaining the AC component of the d-q-axis current obtained in the d-q coordinate conversion step, and the d-q-axis current AC component obtained in the current-AC component detecting step. A step-out detection step of detecting step-out by comparing one with a step-out level signal that is arbitrarily set, is provided.

The step-out detection method for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position,
A current detection step of detecting a current flowing through the synchronous motor, and a dq coordinate conversion for converting the current signal obtained in the current detection step into an excitation current component (d-axis current) and a torque current component (q-axis current). Step, current AC component detection step for obtaining AC component of dq axis current obtained in dq coordinate conversion step, and effective value of dq axis current AC component obtained in current AC component detection step or At least the AC component averaging step of averaging the absolute value of the dq axis current AC component and the average value of the dq axis current AC component obtained by the AC component averaging step. A step out detection step of detecting out-of-step by comparing any one of the steps with an arbitrarily set out-of-step level signal.

The step-out detection method for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting the rotor position,
A current detection step of detecting a current flowing through the synchronous motor, and a dq coordinate conversion for converting the current signal obtained in the current detection step into an excitation current component (d-axis current) and a torque current component (q-axis current). Step, a current error calculation step for obtaining an error between the dq coordinate current obtained in the dq coordinate conversion step and the dq coordinate current command value, and a dq axis current obtained in the current error calculation step A current error crossing component detection step of detecting an AC component of the error, at least one of the dq axis current error AC components obtained in the current error AC component detection step, and a step out level signal set arbitrarily. And a step out detecting step of detecting step out by comparison.

Further, the step-out detection method for the synchronous motor according to the present invention is characterized in that when the AC component is detected from the dq coordinate system current, only a specific frequency component is detected.

Further, the step-out detection method for a synchronous motor according to the present invention is characterized in that the specific frequency component has a frequency twice the frequency of the voltage output from the inverter device.

Further, the step-out detection method for the synchronous motor according to the present invention, when detecting the AC component of the dq axis current error,
The feature is that only a specific frequency component is detected.

The step-out detection method for a synchronous motor according to the present invention is characterized in that the step-out detection level compared with the averaged value of the q-axis current AC component is about 200% of the rated current of the synchronous motor. And

Further, in the step-out detection method for the synchronous motor according to the present invention, when step-out detection becomes difficult at low speed rotation,
Immediately after startup, the system is characterized by accelerating to the steady-state operating speed to detect out-of-step.

Further, in the step-out detection method for a synchronous motor according to the present invention, when there is a possibility that an erroneous detection of step-out detection may occur during acceleration / deceleration of the synchronous motor, the step-out detection is performed in a step other than the acceleration / deceleration process. It is characterized by performing processing.

The step-out detection method for a synchronous motor according to the present invention is an inverter device for driving a synchronous motor without using a position sensor for detecting the rotor position,
Obtained in the current detection step for detecting the current flowing in the synchronous motor, the output voltage command calculation step for obtaining the output voltage command value to be applied to the synchronous motor from the current signal obtained in the current detection step, and the output voltage command calculation step An output voltage vector calculation step for obtaining an output voltage vector based on the output voltage command value; an output voltage abnormality detection step for comparing the magnitude of the output voltage vector obtained by the output voltage vector calculation step with a step-out detection level; A step out detection step of detecting step out from the comparison result obtained in the voltage abnormality detection step.

A hermetic compressor drive device according to the present invention is equipped with the step-out detection device for a synchronous motor according to any one of claims 1 to 10.

A fan motor drive device according to the present invention is equipped with the step-out detection device for a synchronous motor according to any one of claims 1 to 10.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 to 6 are diagrams showing the first embodiment, FIG. 1 is a diagram showing the configuration of an inverter device, FIG. 2 is a diagram illustrating various waveforms during synchronous operation, and FIG. 3 is a diagram illustrating various waveforms during step-out. FIG. 4, FIG. 4 is a flowchart of step-out detection processing, and FIG.
Is a diagram for explaining various waveforms at the time of step out, and FIG. 6 is a flowchart of step out detection processing.

In FIG. 1, 1 is a DC power supply unit, 2 is an inverter device, 3 is a plurality of switching elements, and 3a
Is a U-phase upper switching element, 3b is a V-phase upper switching element, 3c is a W-phase upper switching element, 3d is U
Lower phase switching element 3e is a lower V phase switching element, and 3f is a lower W phase switching element. Reference numeral 4 is a plurality of freewheeling diodes connected in parallel with the plurality of switching elements 3, 5 is an inverter main circuit including the plurality of switching elements 3 and the plurality of freewheeling diodes 4, and 6 is a DC brushless motor.

Reference numeral 7a is a current detecting means for detecting a one-phase current of the current flowing into the DC brushless motor 6, 7b is a current detecting means for detecting a current of a phase different from the current detecting means 7a, and 8 is a current detecting means 7a. , 7b is an inverter control means for controlling on / off of the switching element 3 in the inverter main circuit 5 based on the current value detected.

Reference numeral 9 is a PWM signal generating means for generating a PWM signal for controlling ON / OFF of the switching element 3 based on the output voltage command value obtained in the inverter control means 8, and 10 is detected by the current detecting means 7a, 7b. Was done 2
Phase current calculation means for obtaining the current values of the three phases from the current values of the phases, and 11 dq coordinates for converting the current values of the three phases obtained by the phase current operation means 10 into the current values of the dq coordinate system. Three-phase / two-phase conversion means, which is a conversion means, 12 is an output voltage of the dq-coordinate system for driving the DC brushless motor based on the current value of the dq coordinate system obtained by the three-phase / two-phase conversion means 11. A voltage command value calculation means for obtaining a command value, 13 is an output voltage vector calculation means for obtaining an output voltage vector based on the output voltage command value of the dq coordinate system obtained by the voltage command value calculation means 12, and 14 is a DC power supply. 1 is a DC voltage detecting means for detecting the DC voltage of 1.

Reference numeral 15 is an AC component detecting means for detecting an AC component of the dq coordinate system current obtained by the three-phase / two-phase converting means 11, and 16 is a dq coordinate system current obtained by the AC component extracting means 15. Step-out detection means for detecting the step-out by comparing the AC component and the step-out level.

The operation of the inverter device configured as described above will be described with reference to FIG. In the figure, the inverter device 2 detects currents of two phases out of the phase currents flowing into the DC brushless motor 6 by the current detecting means 7a and 7b. Detected currents for two phases, for example, U-phase currents Iu and V
Using the phase current Iv, the inverter control means 8 drives the inverter main circuit 5 to drive the DC brushless motor 6.
The output voltage command value such as the voltage value and the voltage phase output by is calculated, and the PWM signal for controlling the ON / OFF of the switching element 3 in the inverter main circuit 5 is output.

The inverter control means 8 outputs the PWM signal by the operation described below. The phase currents Iu, Iv detected by the current detecting means 7a, 7b are used by the phase current calculating means 10 to generate phase currents Iu, Iv, Iw for three phases.
And the phase current I for three phases is obtained by the three-phase / two-phase conversion means 11.
u, Iv, and Iw are converted into currents Id and Iq in the dq coordinate system. The voltage command value calculation means 12 calculates the output voltage command value V in the dq coordinate system from the currents Id and Iq in the dq coordinate system.
d ^* and Vq ^* are calculated. The output voltage vector calculation means 13 uses the output voltage command values Vd ^* and Vq ^{* of the} dq coordinate system ^.
Then, the output voltage vector Vx ^* is calculated. PW
The M signal generating means 9 obtains and outputs a PWM signal for controlling the on / off of the switching element 3 from the direct current voltage Vdc obtained from the direct current voltage detecting means 14 and the output voltage vector Vx ^* .

P output by the PWM signal generating means 9
The switching element 3 in the inverter main circuit 5 is turned on / off by the WM signal. Power is supplied from the inverter main circuit 5 to the DC brushless motor 6 by the ON / OFF operation of the switching element 3, and the DC brushless motor is driven.

Dq obtained from the three-phase / two-phase conversion means 11
From the coordinate system currents Id and Iq, the AC component detecting means 15 d-
AC component Id_AC, Iq_ of q coordinate system currents Id, Iq
Detect AC. The out-of-step detection means 16 detects the alternating current components Id_AC and Iq_AC of the dq coordinate system current and the out-of-step detection level E.
Compare error_Level, Id_AC or I
When q_AC exceeds the out-of-step detection level Error_Level, it is out of step and an abnormal stop signal is output.

When the abnormal stop signal is output from the step-out detection means 16, the PWM signal generation means 9 outputs a signal for turning off all the switching elements 3 in the inverter main circuit 5, and the inverter main circuit 5 outputs a direct current. The power supply to the brushless motor 6 is stopped. At the same time, the operation of the inverter control means 8 is also stopped.

Next, details of the step-out detection method according to the present embodiment will be described with reference to FIGS. The waveform diagram shown in FIG. 2 shows an example of various waveforms when the DC brushless motor 6 is normally operating in synchronization. In FIG. 2, the waveform (a) is the phase current waveform Iu obtained by the current detection means 7a, the waveform (b) is the d-axis current waveform Id obtained by the three-phase / two-phase conversion means, and the waveform (c) is the three-phase / two-phase. Conversion means 11
The q-axis current waveform Iq and the waveform (d) obtained by the above show the AC component waveform Iq_AC of the q-axis current Iq.

The waveforms shown in FIG. 3 are examples of various waveforms when the DC brushless motor is out of step.
In FIG. 3, the waveform (a) is the phase current waveform Iu obtained by the current detection means 7a, the waveform (b) is the d-axis current waveform Id obtained by the three-phase two-phase conversion means, and the waveform (c) is the three-phase two-phase. Q-axis current waveform Iq obtained from the conversion means 11, waveform (d)
Indicates an AC component waveform Iq_AC of the q-axis current Iq.

As shown in FIGS. 2 and 3, when the DC brushless motor is in the synchronous operation state, the dq coordinate system current I
d and Iq are almost DC, but in the case of step out state, Id and Iq
An alternating current component is generated in q. As shown in the waveform (d) of FIG.
The AC components Id_AC and Iq_AC of d and Iq are compared with the out-of-step detection level Error_Level, and if it exceeds the out-of-step detection level, out-of-step is determined. With such an operation, it is possible to detect out-of-step. Here, a phenomenon in which an AC component is generated in Id and Iq will be described below. Particularly, in a motor such as an IPMSM (embedded magnet type synchronous motor) having different d-axis and q-axis inductances, in a synchronous operation state, the relationship between the rotor phase and the output voltage phase of the inverter maintains a constant phase difference. That is, when the output voltage phase of the inverter is used as a reference, the d-axis current Id and the q-axis current Iq operate because the d-axis and q-axis inductances of the rotor are operating in a constant state.
Becomes almost direct current. On the other hand, in the step-out state, the relationship between the rotor phase and the output voltage phase of the inverter constantly changes, that is, when the output voltage phase of the inverter is used as a reference, the d-axis and q-axis inductances always change. Therefore, the d-axis current and the q-axis current fluctuate for each rotation phase, and an AC component is generated in each. Thus, d-
By detecting the AC component of the q-axis current, it is possible to capture the variation in the d-axis and q-axis inductance of the rotor (operating state of the rotor) as seen from the output voltage phase of the inverter. Step out can be detected.

With reference to FIG. 4, as an example of the step-out detecting means in the first embodiment, means for using the q-axis current Iq corresponding to the output torque component of the current flowing into the motor will be described. FIG. 4 is a flowchart showing the flow of step-out detection processing. In FIG. 4, STP1 is step-out detection start processing, STP2 is phase current detection processing, STP3 is phase current calculation processing, STP4 is three-phase / two-phase conversion processing, STP5 is AC component detection processing, and STP6 is step-out level comparison. Processing, STP
7 is PWM stop processing, STP8 is abnormal end processing, STP
Reference numeral 9 is a normal termination process.

The flow of out-of-step detection is as follows. ST
The step-out detection process is started by P1, and the two-phase currents Iu and Iv flowing into the DC brushless motor 6 are detected by the current detection means 7a and 7b in the phase current detection process of STP2. In the phase current calculation process of STP3, the currents Iu, Iv for three phases are calculated from the currents Iu, Iv for two phases obtained in STP2.
Find Iw. In the three-phase / two-phase conversion process of STP4, STP
The three-phase currents Iu, Iv, and Iw obtained in 4 are converted into currents Id and Iq in the dq coordinate system. In the AC component detection process of STP5, the AC component Iq_AC of the q-axis current Iq obtained in STP4 is detected by the high pass filter.

In the step-out level comparison processing of STP6, STP
The q-axis current AC component Iq_AC obtained in 5 is compared with the out-of-step level Error_Level, and Iq_AC ≧ E
In the case of error_Level, the step is lost, and the process proceeds to STP7. If Iq_AC <Error_Level: Synchronous operation is in progress, and the process proceeds to STP9. In the PWM stop processing of STP7, when it is determined that the step is out of step in STP6, all the PWM signals output from the PWM signal generating means 9 are stopped, and the operation of the inverter control means is stopped. STP8
In the abnormal end processing of (1), the out-of-step detection ends as an out-of-step abnormality. In the normal termination process of STP9, the out-of-step detection process is terminated because it is operating normally.

As described above, since the step-out of the DC brushless motor is detected by detecting the changes in the dq axis currents occurring during the normal operation and the step-out, as compared with the conventional step-out detection by the overcurrent phenomenon. It is possible to detect out-of-step more accurately.

Since the q-axis current Iq corresponding to the output torque component of the current flowing into the motor is proportional to the output torque, erroneous detection may occur if out-of-step is detected at the q-axis current level. Therefore, by detecting the AC component of Iq,
Even under the condition that the output torque is different, it becomes possible to detect the step-out more accurately.

Further, since the variable used in the calculation of the output voltage command value is used in the inverter control means 8, means such as induced voltage estimation means is not required, so that the step-out detection processing can be simplified. Is.

Next, another configuration of the synchronous motor out-of-step detecting device according to the first embodiment of the present invention will be described with reference to FIG. Here, the configuration of the inverter device is the same as that in FIG. The waveform diagram shown in FIG. 5 shows an example of various waveforms when the DC brushless motor 6 is out of step. In FIG. 5, the waveform (a) is the phase current waveform Iu obtained from the current detecting means 7a, and the waveform (b) is the three-phase / two-phase converting means 11.
The obtained d-axis current waveform Id, waveform (c) is the q-axis current waveform Iq obtained by the three-phase / two-phase conversion means, waveform (d) is the AC component waveform Iq_AC of the q-axis current Iq, and waveform (e) is q. A q-axis current AC component absolute value waveform | Iq_AC | obtained by rectifying the shaft current AC component Iq_AC, and a waveform (f) shows a waveform Iq_AC_Fil obtained by filtering the q-axis current AC component absolute value by a low-pass filter.

As shown in FIGS. 2 and 5, when the DC brushless motor is in the synchronous operation state, the dq coordinate system current I
d and Iq are almost DC, but in the case of step out state, Id and Iq
An alternating current component is generated in q. As shown in the waveform (f) of FIG.
The values Id_AC_Fil and Iq_AC_F obtained by filtering the AC component absolute values of d and Iq with a low-pass filter.
il is compared with the out-of-step detection level Error_Level, and if it exceeds this, it is out of step. With such an operation, it is possible to detect out-of-step.

With reference to FIG. 6, as an example of the step-out detecting means, a means for using the q-axis current Iq corresponding to the output torque component of the current flowing into the motor will be described. FIG. 6 is a flow chart showing the flow of the process of step-out detection. In FIG. 6, STP1 is a step out detection detection process, STP2 is a phase current detection process, STP3 is a phase current calculation process, and STP4.
Is a three-phase two-phase conversion process, STP5 is an AC component detection process, S
TP10 is a rectification (absolute value calculation) process, STP11 is a low-pass filtering process, STP12 is a step out level comparison process, STP7 is a PWM stop process, STP.
8 is an abnormal process, and STP 9 is a normal end process.

The flow of step-out detection is as follows. ST
The step-out detection process is started by P1, and the two-phase currents Iu and Iv flowing into the DC brushless motor 6 are detected by the current detection means 7a and 7b in the phase current detection process of STP2. In the phase current calculation process of STP3, the currents Iu, Iv for three phases are calculated from the currents Iu, Iv for two phases obtained in STP2.
Find Iw. In the three-phase / two-phase conversion process of STP4, STP
The three-phase currents Iu, Iv, and Iw obtained in 4 are converted into currents Id and Iq in the dq coordinate system. In the AC component detection process of STP5, the AC component Iq_AC of the q-axis current Iq obtained in STP4 is detected by the high pass filter.

In the rectification (absolute value calculation) processing of STP10, the q-axis current AC component Iq_AC obtained in STP5 is rectified to obtain the absolute value | Iq_AC | of Iq_AC. STP
In the filtering process of No. 11, | Iq_AC | is filtered using a low-pass filter to obtain an absolute value filter value Iq_AC_Fil of the alternating current component of Iq. STP
The step-out level comparing means 12 compares Iq_AC_Fil with the step-out level Error_Level to obtain Iq_A.
If C_Fil ≥ Error_Level, step out occurs and the process proceeds to STP7. Iq_AC_Fil <Err
In the case of or_Level, it is determined that the synchronous operation is in progress, and the process proceeds to STP9. In the PWM stop processing of STP7, when it is determined that the step is out of step in STP6, all the PWM signals output from the PWM signal generating means 9 are stopped, and the operation of the inverter control means is stopped. In the abnormal end processing of STP8, the out-of-step detection ends as an out-of-step abnormality. In the normal termination process of STP9, the out-of-step detection process is terminated because it is operating normally.

As described above, since the step-out of the DC brushless motor is detected by detecting the changes in the dq axis currents occurring during the normal operation and the step-out, as compared with the conventional step-out detection by the overcurrent phenomenon. It is possible to detect out-of-step more accurately.

Further, since the q-axis current Iq corresponding to the output torque component of the current flowing into the motor is proportional to the output torque, when the out-of-step is simply detected at the q-axis current level, the rotation speed and the load torque Since it is necessary to set the out-of-step level according to the conditions, the configuration becomes complicated. However, by detecting the alternating current component of Iq as in the first embodiment of the present invention, it becomes possible to detect the out-of-step more accurately even under the condition that the output torque is different.

Similarly, even when the d-axis current value is used for out-of-step detection, the d-axis current value changes depending on the operating conditions of the synchronous motor, such as the rotation speed and the load torque. When detecting a step-out at the level of the d-axis current, it is necessary to set the step-out level according to the conditions of the number of revolutions and the load torque. However, by detecting the AC component of Id as in the first embodiment of the present invention, it becomes possible to detect the step-out more accurately even under the condition that the operating state of the synchronous motor is different.

Further, since the variable used to calculate the output voltage command value is used in the inverter control means 8, means such as induced voltage estimation means is not required, so that the step-out detection processing can be simplified. Is.

Further, the absolute value of the AC component Iq_AC of the q-axis current is taken as | Iq_AC |, and the value Iq_AC_Fil obtained by filtering the value with a low-pass filter is used for out-of-step detection. It is possible to improve accuracy. The AC component Iq_AC of the q-axis current may temporarily become large due to a sudden load torque change or a change in the voltage of the DC power supply 1 even if the out-of-step state is not established. However, Iq_AC_Fil is used for out-of-step detection. By using it, it is possible to avoid erroneous detection of a step-out state due to the above state.

Here, an example of setting the out-of-step detection level for comparison at the time of out-of-step detection will be described. q-axis current value Iq
The AC component Iq_AC of is generated due to fluctuations in load torque even in the synchronous operation state. However, the level of Iq_AC that occurs during normal operation is Iq_A that occurs during step out.
Since it is smaller than the C level, the set level can be set to be higher than the Iq_AC level generated during normal operation and lower than the Iq_AC level generated during step out. Since there is a large difference between the Iq_AC generation levels at the normal time and at the time of step-out, the setting is easy.

An example of the step out level set value will be described below. The level of the average value Iq_AC_Fil of the AC component of the q-axis current Iq generated during step-out with respect to a DC brushless motor whose rated current is about 0.5 A is 50% or less of the rated current effective value within the rated operating range. On the other hand, the q-axis current AC component average value Iq_A generated during step out
The level of C_Fil was 250% or more of the rated current effective value in the rated operating range. Therefore, in consideration of the effects of load torque fluctuations and DC voltage fluctuations, the rated current effective value of 2
It is conceivable that the out-of-step detection level is set to 00%.

Another example of setting the step-out level will be described below. As an example of the load of the synchronous motor, for a compressor, particularly a compressor with a large load fluctuation during one rotation such as a single-rotor retype compressor, the q-axis current Iq is generated due to torque ripple due to the effect of the load fluctuation. The AC component Iq_AC becomes slightly large, but Iq_AC at the time of step-out does not become so large. The out-of-step detection level may be set to be higher than usual.

In the step-out detection method shown in the first embodiment of the present invention, the step-out detection is difficult at low speed rotation because the current flowing into the DC motor at low speed is small depending on the combination of the inverter device and the DC brushless motor. There is a condition that In such a case, the detection can be performed by accelerating to the steady operation rotation speed immediately after starting. At this time, the step-out state continues until the detection, but the time is several seconds, and the flowing current is smaller than that in the rated operation, so there is almost no adverse effect on the inverter device or the synchronous motor.

When the DC brushless motor is accelerated or decelerated, AC components may be generated in the dq coordinate system currents Id and Iq, which may cause erroneous detection of step-out detection.
In such a case, the step-out detection process is not performed during the acceleration / deceleration, and the detection can be performed by performing the detection in a process other than the acceleration / deceleration process.

Here, in the flow chart for step-out detection shown in FIG. 4 or FIG. 6, when the AC component is detected from the dq coordinate system current in STP5, a band pass filter or FF is used.
By using a means for detecting only a specific frequency component using T (Fast Fourier Transform) or the like, it becomes possible to further improve the step-out detection accuracy. As an example of the specific frequency component, a frequency twice the frequency of the voltage output from the inverter device is raised. This is because, for example, in the case of a 4-pole motor, the dq coordinate system current at the time of step-out contains many frequency components twice the rotation frequency of the voltage output from the inverter device. When determining the specific frequency component, as an example, there is a method of determining it from the number of poles of the motor.

As the step-out detection method in the first embodiment, q
Although the means for using the axis current value has been described, the same step-out can be achieved by using the error between the d-axis current value, the d-axis current command value and the d-axis current, or the error between the q-axis current command value and the q-axis current. It is possible to detect. Here, the d-axis current command value and the q-axis current command value are command values for appropriately controlling the synchronous motor when driving and controlling the synchronous motor, and are values determined by the operating conditions of the synchronous motor. .

When step-out detection is performed using the error between the d-axis current command value and the d-axis current and the error between the q-axis current command value and the q-axis current, the three phases obtained by the phase current calculating means 10 are obtained. Dq obtained by the three-phase / two-phase conversion means 11 which is the dq coordinate conversion means for converting the current value of the above into the current value of the dq coordinate system.
The error between the coordinate current and the dq coordinate current command value is obtained, the AC component of the obtained dq axis current error is detected, and at least one of the detected dq axis current error AC component is arbitrary. Step-out is detected by comparing with the step-out level signal set to.

When the q-axis current value is used for out-of-step detection, the q-axis current corresponds to the torque component of the current flowing through the synchronous motor. Therefore, the case where a large AC component is generated in the q-axis current is the case where the output torque of the electric motor fluctuates greatly, and corresponds to the case where the operation is abnormal. Here, even in the steady operation, an AC component is generated in the q-axis current due to the change in the load torque, but it is smaller than the AC component generated in the step-out. As described above, since the change in the q-axis current is related to the operation of the electric motor, it is easy to distinguish the normal time from the step-out time. Therefore, the means that uses the q-axis current for step-out detection facilitates setting of the step-out level.

When the d-axis current is used for detecting out-of-step,
Like the q-axis current, the d-axis current produces an AC component at the time of step-out, so that it is possible to detect the step-out like the q-axis current.

Further, when both the d-axis current and the q-axis current are used, the step-out detection accuracy is improved because the step-out is detected from a plurality of information. The same applies to the case where the d-axis current value and the q-axis current value are used for conversion into at least one detected amount other than the d-axis current or the q-axis current using coordinate conversion or an arithmetic expression.

The d-axis current and the q-axis current are generally defined by defining the magnetic pole direction of the rotor of the electric motor as the d-axis and the phase advanced by 90 degrees from the d-axis in the rotation direction as the q-axis. However, when the synchronous motor is driven without a position sensor, the dq
Since it is difficult to detect the axis, the axis corresponding to the d axis may be defined as the δ axis and the axis corresponding to the q axis may be defined as the γ axis as a coordinate system for control, but in the δ-γ axis coordinate system, It goes without saying that can also be realized with a similar configuration.

In the above embodiment, when averaging the dq axis current AC components, the absolute value of the AC component of the dq axis current is taken and the absolute value is filtered to obtain the dq axis current. The average value of the AC component of the current was calculated.
The effective value of the q-axis current AC component may be obtained and used as the AC component averaged value of the dq axis current.

Embodiment 2. 7 and 8 are diagrams showing the second embodiment, and FIG. 7 is a diagram showing the configuration of the inverter device.
6 is a flow chart of step-out detection processing. In FIG. 7, 1 is a DC power supply unit, 2 is an inverter device, 3 is a plurality of switching elements, 3a is a U-phase upper side switching element, 3b.
Is a V-phase upper switching element, 3c is a W-phase upper switching element, 3d is a U-phase lower switching element, 3e is V
Lower phase switching element 3f is a lower W phase switching element. Reference numeral 4 is a plurality of freewheeling diodes connected in parallel with the plurality of switching elements 3, 5 is an inverter main circuit including the plurality of switching elements 3 and the plurality of freewheeling diodes 4, and 6 is a DC brushless motor.

Reference numeral 7a is a current detecting means for detecting one phase current of the current flowing into the DC brushless motor 6, 7b is current detecting means for detecting a current of a phase different from the current detecting means 7a, and 8 is current detecting means 7a. , 7b is an inverter control means for controlling on / off of the switching element 3 in the inverter main circuit 5 based on the current value detected.

Reference numeral 9 is a PWM signal generating means for generating a PWM signal for turning on / off the switching element 3 based on the output voltage command value obtained in the inverter control means 8, and 10 is detected by the current detecting means 7a, 7b. Was done 2
Phase current calculating means for obtaining the current value of the three phases from the current value for the phase, 11 is a three-phase two-phase conversion for converting the current value of the three phases obtained by the phase current calculating means into the current value of the dq coordinate system. means,
Reference numeral 12 is a voltage command value calculating means for obtaining an output voltage command value of the dq coordinate system for driving the DC brushless motor based on the dq coordinate system current value obtained by the three-phase / two-phase converting means 11. Is an output voltage vector calculating means for obtaining an output voltage vector based on the output voltage command value of the dq coordinate system obtained by the voltage instruction value calculating means 12, and 14 is a DC voltage detecting means for detecting the DC voltage of the DC power supply 1. Is.

Reference numeral 17 is an output voltage abnormality detection means for comparing the magnitude | Vx ^* | of the output voltage vector Vx ^* obtained by the output voltage vector calculation processing 13 with the step-out detection level V_Error_Level, and 18 is an output voltage abnormality detection means. 1
Step-out detection means for detecting step-out based on the comparison result obtained from FIG.

The operation of the inverter device configured as described above will be described with reference to FIG. In the figure, the inverter device 2 detects currents of two phases out of the phase currents flowing into the DC brushless motor 6 by the current detecting means 7a and 7b. Detected currents for two phases, for example, U-phase currents Iu and V
Using the phase current Iv, the inverter control means 8 drives the inverter main circuit 5 to drive the DC brushless motor 6.
The output voltage command value such as the voltage value and the voltage phase output by is calculated, and the PWM signal for controlling the ON / OFF of the switching element 3 in the inverter main circuit 5 is output.

The inverter control means 8 outputs the PWM signal by the operation described below. The phase currents Iu, Iv detected by the current detecting means 7a, 7b are used by the phase current calculating means 10 to generate phase currents Iu, Iv, Iw for three phases.
And the phase current I for three phases is obtained by the three-phase / two-phase conversion means 11.
u, Iv, and Iw are converted into currents Id and Iq in the dq coordinate system. The voltage command value calculation means 12 calculates the output voltage command value V in the dq coordinate system from the currents Id and Iq in the dq coordinate system.
d ^* and Vq ^* are calculated. The output voltage vector calculation means 13 uses the output voltage command values Vd ^* and Vq ^{* of the} dq coordinate system ^.
Then, the output voltage vector Vx ^* is calculated. PW
The M signal generating means 9 obtains and outputs a PWM signal for controlling the on / off of the switching element 3 from the direct current voltage Vdc obtained from the direct current voltage detecting means 14 and the output voltage vector Vx ^* .

P output by the PWM signal generating means 9
The switching element 3 in the inverter main circuit 5 is turned on / off by the WM signal. Power is supplied from the inverter main circuit 5 to the DC brushless motor 6 by the ON / OFF operation of the switching element 3, and the DC brushless motor is driven.

The output voltage vector Vx ^* obtained from the output voltage vector calculation means 13 is the output voltage abnormality detection means 17
After the magnitude of the vector | Vx ^* | is calculated in step S1, the step out level is compared with the step out level V_Error_Level, and if the step out level is below the step out level V_Error_Level, step out occurs. On the other hand, step-out level V_Error_Lev
If it exceeds el, it is assumed that the synchronous operation is normally performed.

In the step-out detecting means 18, | Vx ^* | is step-out level V_Error_L as a result of the output voltage abnormality detection processing.
If it falls below the level, the step is lost and an abnormal stop signal is output to the PWM signal generating means 9. PWM signal generating means 9
When the abnormal stop signal is received, outputs a signal for turning off all the switching elements 3 in the inverter main circuit 5 to stop the operation of the switching elements. At the same time, the operation of the inverter control device is stopped. With such an operation, step out can be detected.

An example of the flow of the step-out detection processing in the second embodiment will be described with reference to FIG. FIG. 8 is a flow chart showing the flow of the process of step-out detection. In FIG. 8, STP1 is step-out detection start processing, STP13 is output voltage vector detection processing, STP14 is output voltage vector magnitude detection processing, STP15 is step-out level comparison processing, STP7 is PWM stop processing, and STP8 is abnormal termination. The process, STP9, is a normal end process.

Step out detection processing is started at STP1, and STP is started.
The output voltage vector Vx ^* obtained from the output voltage vector calculation process 13 is detected in the output vector detection process 13 of
STP1 in the output vector magnitude detection process of STP14
Magnitude of output voltage vector Vx ^* detected in 3 | Vx ^* |
Ask for. In the step-out level comparison processing of STP15, the magnitude of the output voltage vector | Vx ^* | and the step-out level V_Err
or_Level is compared, and | Vx ^* | <V_Er
In the case of ror_Level, the step is lost and the process proceeds to STP7. On the other hand, if | Vx ^* | ≧ V_Error_Level, it is assumed that the synchronous operation is normally performed, and the process proceeds to STP9.

In the PWM stop processing of STP7, when it is judged that the step is out of step in STP6, all the PWM signals output from the PWM signal generating means 9 are stopped, and the operation of the inverter control means is stopped. In the abnormal end processing of STP8, the out-of-step detection ends as an out-of-step abnormality. In the normal termination process of STP9, the out-of-step detection process is terminated because it is operating normally.

When driving a DC brushless motor, if the output voltage is below the level required to continue the synchronous operation, the synchronous operation cannot be continued and step out occurs. Therefore, it becomes possible to detect step-out from this phenomenon. This detection can be realized by the operation shown in the second embodiment. here,
Output voltage vector magnitude | Vx ^* | according to operating conditions
Is different, the step-out level V_Error_Level is set according to the operating conditions.

As described above, the step-out of the DC brushless motor is detected by detecting the difference between the output voltage vector | Vx ^* | generated during the normal synchronous operation and the step-out. Out-of-step detection can be performed with higher accuracy than detection.

Further, since the variable used in the calculation of the output voltage command value is used in the inverter control means 8, means such as an induced voltage estimation means is not required, and the step-out detection processing can be simplified. .

Here, a DC brushless motor has been taken as an example of the synchronous motor according to the first and second embodiments of the present invention. It is needless to say that the same effect can be obtained even with such a thing.

An example of a device equipped with the step-out detection device for a synchronous motor according to the present invention is a compressor drive device for a refrigerator-freezer or an air conditioner. By installing it in the compressor drive device, compressor noise that occurs when step-out continues, damage to the refrigerant pipe due to vibration of the compressor, or demagnetization of the magnet used in the rotor of the electric motor Problems such as breakage of semiconductor elements can be improved. This makes it possible to realize a highly reliable refrigerator / freezer or air conditioner.

As an example of a device equipped with the step-out detection device for a synchronous motor according to the present invention, a fan motor drive device for a refrigerator-freezer or an air conditioner can be used. When installed in a fan motor drive, fan motor noise that occurs when step-out continues, vibration of the fan motor, demagnetization of magnets used in the rotor of the motor, or destruction of semiconductor elements in the inverter device due to increased current, etc. The problems of can be improved. This makes it possible to realize a highly reliable refrigerator / freezer or air conditioner.

[0099]

The step-out detecting device for a synchronous motor according to the present invention detects the current flowing through the synchronous motor, and the current signal obtained by the current detecting device as an exciting current component (d-axis current). Dq coordinate conversion means for performing coordinate conversion into a torque current component (q axis current), current alternating current component detection means for obtaining an alternating current component of the dq axis current obtained by the dq coordinate conversion means, current alternating current By including at least one of the dq axis current AC components obtained by the component detecting means and the out-of-step detecting means for detecting an out-of-step by comparing an arbitrarily set out-of-step level signal, With a simplified configuration, it is possible to detect a step out with high accuracy. Also,
It is possible to prevent destruction of the inverter main circuit element due to demagnetization of the magnet in the rotor and increase in current, which occur due to the continuation of the step-out state. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, in the step-out detecting device for the synchronous motor according to the present invention, the current detecting means for detecting the current flowing through the synchronous motor, and the current signal obtained by the current detecting means are used as the exciting current component (d-axis current). Dq coordinate conversion means for performing coordinate conversion into a torque current component (q axis current), current alternating current component detection means for obtaining an alternating current component of the dq axis current obtained by the dq coordinate conversion means, current alternating current AC component averaging means for averaging the effective value or absolute value of the dq axis current AC component obtained by the component detecting means, and averaging the dq axis current AC component, and AC component averaging D obtained by means
-Since the step-out detecting means for detecting step-out by comparing at least one of the averaged values of the q-axis current AC component with an arbitrarily set step-out level signal, is simplified. With a simple structure, it becomes possible to detect the out-of-step accurately. Further, since an averaged value is used as the value used for detection, it is possible to prevent misstep detection due to load torque fluctuation of the synchronous motor or voltage fluctuation. Further, it is possible to prevent the main circuit element of the inverter from being destroyed due to the demagnetization of the magnet in the rotor of the synchronous motor and the increase in the current that occur due to the continuous out-of-step condition. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, the step-out detecting device for the synchronous motor according to the present invention detects the current flowing through the synchronous motor, and the current signal obtained by the current detecting device as the exciting current component (d-axis current). A dq coordinate conversion means for performing coordinate conversion into a torque current component (q axis current), and a current for obtaining an error between the dq coordinate current obtained by the dq coordinate conversion means and the dq coordinate current command value. Error calculating means, current error crossing component detecting means for detecting an alternating current component of the dq axis current error obtained by the current error calculating means, and dq axis current error alternating current obtained by the current error alternating current component detecting means The step-out detection means for detecting the step-out by comparing at least one of the components with an arbitrary step-out level signal is detected, so that the step-out can be detected accurately with a simplified configuration. It becomes possible to do. Further, it is possible to prevent the main circuit element of the inverter from being destroyed due to the demagnetization of the magnet in the rotor of the synchronous motor and the increase in the current that occur due to the continuous out-of-step condition.
In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

The step-out detection device for a synchronous motor according to the present invention improves step-out detection accuracy by detecting only a specific frequency component when detecting an AC component from the dq coordinate system current. be able to.

Further, in the step-out detection device for a synchronous motor according to the present invention, the step-out detection accuracy is improved by setting the specific frequency component to be twice the frequency of the voltage output from the inverter device. You can

In addition, the step-out detection device for a synchronous motor according to the present invention detects the AC component of the dq axis current error,
By detecting only the specific frequency component, the step-out detection accuracy can be improved.

Further, in the step-out detection device for a synchronous motor according to the present invention, the step-out detection level to be compared with the average value of the q-axis current AC component is set to about 200% of the rated current of the synchronous motor. Step-out can be reliably detected without being affected by torque and DC voltage fluctuations.

Further, the step-out detecting device for a synchronous motor according to the present invention, when step-out detection becomes difficult at low speed rotation,
Immediately after the start-up, the out-of-step can be detected by accelerating to the steady operation rotational speed and detecting out-of-step.

Further, the step-out detection device for a synchronous motor according to the present invention detects a step-out in a step other than the acceleration / deceleration process when there is a possibility that an erroneous detection of the step-out detection may occur when the synchronous motor is accelerated or decelerated. By performing the processing, it is possible to detect the out-of-step.

Further, the step-out detecting device for a synchronous motor according to the present invention includes a current detecting means for detecting a current flowing through the synchronous motor, and an output voltage command value applied to the synchronous motor from a current signal obtained by the current detecting means. Of the output voltage vector obtained by the output voltage vector calculation means, and the output voltage vector calculation means for obtaining the output voltage vector based on the output voltage command value obtained by the output voltage command calculation means. A simplified configuration is provided by providing an output voltage abnormality detecting means for comparing the magnitude and the out-of-step detection level and a step-out detecting means for detecting out-of-step from the comparison result obtained by the output voltage abnormality detecting means. Thus, it becomes possible to detect the out-of-step accurately. Further, it is possible to prevent the main circuit element of the inverter from being destroyed due to the demagnetization of the magnet in the rotor of the synchronous motor and the increase in the current that occur due to the continuous out-of-step condition. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, in the step-out detection method for the synchronous motor according to the present invention, the current detection step of detecting the current flowing through the synchronous motor and the current signal obtained in the current detection step are used as the exciting current component (d-axis current). Torque current component (q-axis current)
Dq coordinate conversion step for performing coordinate conversion to and, current AC component detection step for obtaining AC component of dq axis current obtained in dq coordinate conversion step, and d obtained in current AC component detection step -A step-out detection step of detecting out-of-step by comparing at least one of the q-axis current AC components with an arbitrarily set out-of-step level signal, the accuracy is simplified by the configuration. It becomes possible to detect the out-of-step well. Further, it is possible to prevent destruction of the inverter main circuit element due to demagnetization of the magnet in the rotor and increase in current, which occur due to the continuation of the step-out state. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, in the step-out detection method for the synchronous motor according to the present invention, the current detection step of detecting the current flowing through the synchronous motor, and the current signal obtained in the current detection step are used as the exciting current component (d-axis current). Torque current component (q-axis current)
Dq coordinate conversion step for performing coordinate conversion to and, a current AC component detection step for obtaining an AC component of the dq axis current obtained in the dq coordinate conversion step, and d obtained by the current AC component detection step. -Q value obtained by the AC component averaging step of averaging the effective value or absolute value of the q-axis current AC component and averaging the d-q axis current AC component, and the AC component averaging step A step-out detection step of detecting step-out by comparing at least one of the averaged values of the axial current AC component with an arbitrarily set step-out level signal is provided. With the configuration, it is possible to accurately detect the step-out. Further, since an averaged value is used as the value used for detection, it is possible to prevent misstep detection due to load torque fluctuation of the synchronous motor or voltage fluctuation. Further, it is possible to prevent the main circuit element of the inverter from being destroyed due to the demagnetization of the magnet in the rotor of the synchronous motor and the increase in the current that occur due to the continuous out-of-step condition.
In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, in the step-out detection method for the synchronous motor according to the present invention, the current detection step of detecting the current flowing through the synchronous motor and the current signal obtained in the current detection step are used as the exciting current component (d-axis current). Torque current component (q-axis current)
A dq coordinate conversion step for performing coordinate conversion to and a current error calculation step for obtaining an error between the dq coordinate current obtained in the dq coordinate conversion step and the dq coordinate current command value,
A current error cross component detection step of detecting an AC component of the dq axis current error obtained by the current error calculation step;
A step out detection step of detecting step out by comparing at least one of the dq axis current error AC components obtained in the current error AC component detection step with an arbitrarily set step out level signal. As a result, with a simplified configuration,
It becomes possible to detect a step out with high accuracy. Further, it is possible to prevent the main circuit element of the inverter from being destroyed due to the demagnetization of the magnet in the rotor of the synchronous motor and the increase in the current that occur due to the continuous out-of-step condition. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

Further, the step-out detection method for a synchronous motor according to the present invention improves step-out detection accuracy by detecting only a specific frequency component when detecting an AC component from the dq coordinate system current. be able to.

Further, in the step-out detection method for the synchronous motor according to the present invention, the step-out detection accuracy is improved by setting the specific frequency component to twice the frequency of the voltage output from the inverter device. You can

Further, the step-out detection method for the synchronous motor according to the present invention, when detecting the AC component of the dq axis current error,
By detecting only the specific frequency component, the step-out detection accuracy can be improved.

Further, in the step-out detection method for the synchronous motor according to the present invention, the step-out detection level compared with the averaged value of the q-axis current AC component is set to about 200% of the rated current of the synchronous motor. Step-out can be reliably detected without being affected by changes in load torque and DC voltage.

Further, in the step-out detection method for the synchronous motor according to the present invention, when step-out detection becomes difficult at low speed rotation,
Immediately after the start-up, the out-of-step can be detected by accelerating to the steady-state rotation speed and detecting out-of-step.

Further, in the step-out detection method for the synchronous motor according to the present invention, when there is a possibility that the step-out detection may be erroneously detected when the synchronous motor is accelerated or decelerated, the step-out detection may be performed in a process other than the acceleration / deceleration process. By performing the processing, it is possible to detect the out-of-step.

The step-out detection method for a synchronous motor according to the present invention further includes a current detection step of detecting a current flowing through the synchronous motor, and an output voltage command value applied to the synchronous motor from the current signal obtained in the current detection step. Output voltage command calculation step, the output voltage vector calculation step to obtain the output voltage vector based on the output voltage command value obtained in the output voltage command calculation step, and the output voltage vector calculation step A simplified configuration by including an output voltage abnormality detection step of comparing the magnitude and the step-out detection level and a step-out detection step of detecting out-of-step from the comparison result obtained in the output voltage abnormality detection step. Thus, it becomes possible to detect the out-of-step accurately. Further, it is possible to prevent destruction of the inverter main circuit element due to demagnetization of the magnet in the rotor and increase in current, which occur due to the continuation of the step-out state. In addition, it is possible to prevent noise and vibration of the synchronous motor caused by continuing the step-out state.

A hermetic compressor drive device according to the present invention is equipped with the step-out detection device for a synchronous motor according to any one of claims 1 to 10, and is therefore a compressor generated when step-out continues. Problems such as noise, damage to the refrigerant pipe due to vibration of the compressor, demagnetization of magnets used in the rotor of the electric motor, or destruction of semiconductor elements of the inverter device due to increased current can be solved. This makes it possible to realize a highly reliable refrigerator / freezer or air conditioner.

Since the fan motor driving apparatus according to the present invention is equipped with the step-out detecting device for a synchronous motor according to any one of claims 1 to 10, fan motor noise generated when step-out continues, It is possible to solve problems such as vibration of a fan motor, demagnetization of a magnet used for a rotor of an electric motor, or destruction of a semiconductor element of an inverter device due to an increase in current. This makes it possible to realize a highly reliable refrigerator / freezer or air conditioner.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment and is a diagram illustrating a configuration of a step-out detection device for a synchronous motor.

FIG. 2 is a diagram showing the first embodiment and is a diagram for explaining various waveforms during synchronous operation.

FIG. 3 is a diagram showing the first embodiment and is a diagram for explaining various waveforms during step-out.

FIG. 4 shows the first embodiment and is a flowchart showing a flow of step-out detection processing.

FIG. 5 is a diagram showing the first embodiment and is a diagram for explaining various waveforms during step-out.

FIG. 6 is a diagram showing the first embodiment and is a flowchart showing a flow of step-out detection processing.

FIG. 7 is a diagram showing the second embodiment and is a diagram showing a configuration of a step-out detection device for a synchronous motor.

FIG. 8 is a diagram showing the second embodiment and is a flowchart showing a flow of step-out detection processing.

FIG. 9 is a diagram showing a configuration of a conventional step-out detection device for a synchronous motor.

[Explanation of symbols]

1 DC power supply unit, 2 inverter device, 3 switching element, 3a U-phase upper switching element, 3b V-phase upper switching element, 3c W-phase upper switching element, 3d U-phase lower switching element, 3e V-phase lower switching element, 3f W phase lower switching element,
4 reflux diode, 5 inverter main circuit, 6 DC brushless motor, 7a, 7b current detection means, 8 inverter control means, 9 PWM signal generation means, 10 phase current calculation means, 11 3 phase 2 phase conversion means, 12 voltage command value Computing means, 13 output voltage vector computing means, 14
DC voltage detecting means, 15 AC component detecting means, 16 out-of-step detecting means, 17 output voltage abnormality detecting means, 18 out-of-step detecting means.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H560 AA01 BB04 BB12 DC12 DC13                       EB01 EC01 EC10 JJ01 RR10                       SS01 TT08 UA06 XA02 XA12                       XA13                 5H576 AA09 BB06 CC01 DD02 DD07                       EE01 EE11 GG04 HA04 HB02                       JJ26 LL22 LL24 MM01 MM20

Claims (22)

[Claims] 1. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: current detecting means for detecting a current flowing through the synchronous motor; and the current detecting means. D-q coordinate conversion means for coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current), and a d-q-axis current obtained by the dq coordinate conversion means. The current AC component detecting means for obtaining the AC component is compared with at least one of the dq axis current AC components obtained by the current AC component detecting means and a step out level signal which is arbitrarily set to compare with each other. A step-out detection device for a synchronous motor, comprising: step-out detection means for detecting a key. 2. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: current detecting means for detecting a current flowing through the synchronous motor; and the current detecting means. D-q coordinate conversion means for coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current), and a d-q-axis current obtained by the dq coordinate conversion means. An alternating current component detecting means for obtaining an alternating current component and an averaged value of the effective or absolute values of the dq axis current alternating current components obtained by the current alternating current component detecting means are obtained, and d-
AC component averaging means for averaging the q-axis current AC component, and at least one of the averaged values of the d-q-axis current AC components obtained by the AC component averaging means A step-out detection device for a synchronous motor, comprising: step-out detection means for comparing the level signal to detect step-out. 3. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: current detecting means for detecting a current flowing through the synchronous motor; and the current detecting means. Dq coordinate conversion means for coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current); and dq coordinate currents obtained by the dq coordinate conversion means. a current error calculating means for obtaining an error from the dq coordinate current command value; a current error crossing component detecting means for detecting an AC component of the dq axis current error obtained by the current error calculating means; and the current error. Step-out detection means for detecting step-out by comparing at least one of the dq axis current error AC components obtained by the AC component detection means with a step-out level signal set arbitrarily. thing Out detection device for a synchronous motor, wherein. 4. The step-out detection device for a synchronous motor according to claim 1, wherein when detecting an AC component from the dq coordinate system current, only a specific frequency component is detected. 5. The step-out detection device for a synchronous motor according to claim 4, wherein the specific frequency component has a frequency twice the frequency of the voltage output from the inverter device. 6. The step-out detection device for a synchronous motor according to claim 3, wherein only a specific frequency component is detected when detecting the AC component of the d-q axis current error. 7. The out-of-step detection level compared with the average value of the q-axis current AC component is 200% of the rated current of the synchronous motor.
The step-out detection device for a synchronous motor according to claim 2, wherein the step-out detection device is set to a degree. 8. The step-out detection is performed by accelerating to a steady-state operation speed immediately after startup when the step-out detection becomes difficult at low speed rotation. Step-out detection device for synchronous motors. 9. The step-out detection process is performed in a step other than the step of acceleration / deceleration when erroneous detection of step-out detection may occur during acceleration / deceleration of the synchronous motor. The step-out detection device for a synchronous motor according to any one of 1. 10. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: current detecting means for detecting a current flowing through the synchronous motor; and the current detecting means. Output voltage command calculation means for calculating an output voltage command value to be applied to the synchronous motor from a current signal; and output voltage vector calculation means for calculating an output voltage vector based on the output voltage command value obtained by the output voltage command calculation means. An output voltage abnormality detecting means for comparing the magnitude of the output voltage vector obtained by the output voltage vector computing means with a step-out detection level; and step-out detection based on the comparison result obtained by the output voltage abnormality detecting means. A step-out detection device for a synchronous motor, comprising: step-out detection means. 11. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: a current detecting step of detecting a current flowing through the synchronous motor; and a current detecting step. A dq coordinate conversion step for coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current); and a d-q-axis current obtained in the dq coordinate conversion step. Step out by comparing the current AC component detecting step for obtaining the AC component and at least one of the dq axis current AC components obtained in the current AC component detecting step and a step out level signal set arbitrarily. And a step-out detection step for detecting the step-out. 12. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: a current detecting step of detecting a current flowing through the synchronous motor; and an electric current obtained in the current detecting step. A dq coordinate conversion step for coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current); and a d-q-axis current obtained in the dq coordinate conversion step. A current AC component detection step of obtaining an AC component, and an average value of the effective value or the absolute value of the dq axis current AC component obtained by the current AC component detection step is obtained,
The AC component averaging step for averaging the dq axis current AC component, and at least one of the averaged values of the dq axis current AC component obtained by the AC component averaging step are arbitrarily set. A step-out detection method for a synchronous motor, comprising: a step-out detection step of detecting a step-out by comparing with a step-out level signal. 13. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: a current detecting step of detecting a current flowing through the synchronous motor; and an electric current obtained in the current detecting step. A dq coordinate conversion step of coordinate-converting the current signal into an exciting current component (d-axis current) and a torque current component (q-axis current); and a dq coordinate current obtained in the dq coordinate conversion step. a current error calculation step for obtaining an error from the dq coordinate current command value; a current error cross component detection step for detecting an AC component of the dq axis current error obtained in the current error calculation step; Out-of-step detection for detecting out-of-step by comparing at least one of the dq axis current error alternating-current components obtained in the alternating-current component detection step with an arbitrarily set out-of-step level signal Out detection process of the synchronous motor characterized by comprising the steps, a. 14. The step-out detection method for a synchronous motor according to claim 11, wherein when detecting an AC component from the dq coordinate system current, only a specific frequency component is detected. 15. The step-out detection method for a synchronous motor according to claim 14, wherein the specific frequency component has a frequency twice the frequency of the voltage output from the inverter device. 16. The step-out detection method for a synchronous motor according to claim 13, wherein only a specific frequency component is detected when detecting the AC component of the d-q axis current error. 17. The step-out detection level compared with the averaged value of the q-axis current AC component is 20 times the rated current of the synchronous motor.
The step-out detection method for a synchronous motor according to claim 12, wherein the step-out is set to about 0%. 18. The step-out detection is carried out by accelerating to a steady-state rotation speed immediately after starting and detecting the step-out when the step-out detection becomes difficult at low speed rotation. Step-out detection method for synchronous motors. 19. The step-out detection process is performed in a step other than the step of acceleration / deceleration when there is a possibility that an erroneous detection of step-out detection may occur during acceleration / deceleration of the synchronous motor.
14. The step-out detection method for a synchronous motor according to any one of 13 above. 20. An inverter device for driving a synchronous motor without using a position sensor for detecting a rotor position, comprising: a current detecting step of detecting a current flowing through the synchronous motor; and an electric current obtained in the current detecting step. An output voltage command calculation step for obtaining an output voltage command value to be applied to the synchronous motor from a current signal, and an output voltage vector calculation step for obtaining an output voltage vector based on the output voltage command value obtained in the output voltage command calculation step, An output voltage abnormality detection step of comparing the magnitude of the output voltage vector obtained in the output voltage vector calculation step with a step-out detection level; and a step-out detection from the comparison result obtained in the output voltage abnormality detection step. A step-out detection method for a synchronous motor, comprising: a step-out detection step. 21. A drive device for a hermetic compressor, comprising the step-out detection device for a synchronous motor according to claim 1. 22. A fan motor drive device, comprising the step-out detection device for a synchronous motor according to claim 1.