JP2010088261A - Apparatus for detecting abnormality in current sensor of motor - Google Patents

Abstract

An abnormality of a current sensor is detected quickly and accurately.
A motor current sensor abnormality detection device 10 includes a sum of phase currents of three phases at the same timing (phase current sum) based on a detection signal of each phase current of three phases output from each phase current sensor 32. = Iu + Iv + Iw) is not zero, and the detected values of the three-phase currents output from the respective phase current sensors 32 (that is, the respective phase currents Iu, Iv, Iw) are output from the phase current estimating unit 24. If the estimated values Iu ^, Iv ^, Iw ^ of the three-phase currents are not the same, it is determined that the phase current sensor 32 relating to the phase in which the detected value is different from the estimated value is abnormal, When the sum of the phase currents of the three phases at the same timing (phase current sum = Iu + Iv + Iw) is zero and the detected value and the estimated value of each phase current of the three phases are different, the DC side current sensor 31 is Judged to be abnormal.
[Selection] Figure 1

Description

  The present invention relates to a current sensor abnormality detection device for an electric motor.

Conventionally, for example, for each phase current sensor that directly detects each phase current energized from the inverter to the three-phase AC motor, first, it is determined whether or not the sum of the three-phase current is zero. When the sum of the three-phase currents is not zero, it is determined whether an excessive input deviation or output abnormality is detected in the current control system, and the phase in which an excessive input deviation or abnormal output is detected in this determination result. There is known a control device that determines that the phase current sensor is abnormal (see, for example, Patent Document 1).
Japanese Patent No. 2861680

By the way, in the control device according to the prior art, each phase current (actual current) that is actually energized from the inverter to the three-phase AC motor according to the command current changes according to the inductance component of the current control system. For example, even when the command current changes stepwise, the change in the actual current is gradual, and the input deviation (that is, the deviation between the command current and the actual current) is relatively within the response time of the current control system. growing. For this reason, when determining abnormality of the phase current sensor in response to an excessive input deviation, it is necessary to consider the response time of the current control system, and it is difficult to make a highly reliable determination quickly. Problems arise.
Moreover, in a current control system based on general PI (proportional integration) control, if the command current is a lamp input, a steady deviation occurs even after an appropriate response time has elapsed. There is a possibility that the abnormality of the phase current sensor cannot be accurately determined according to the excessive input deviation.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a current sensor abnormality detection device for an electric motor that can quickly and accurately detect an abnormality of a current sensor that detects a current supplied to the electric motor. And

  In order to solve the above problems and achieve the object, the current sensor abnormality detection device for an electric motor according to the first aspect of the present invention is an inverter for sequentially commutating energization to a three-phase AC electric motor by a pulse width modulation signal. A phase current sensor (for example, phase current sensor 32 in the embodiment) for detecting a phase current of the three-phase AC electric motor (for example, the motor 11 in the embodiment), and a DC side current of the inverter A DC side current sensor to be detected (for example, a DC side current sensor 31 in the embodiment), phase current estimation means for estimating the phase current based on the DC current (for example, step S02 in the embodiment), Determining means (for example, step S03 in the embodiment) for determining whether or not the sum of the three phases of the phase current detected by the phase current sensor is zero, and the phase current estimation for each phase Phase current determination means for determining whether or not the estimated value of the phase current estimated by the stage and the detected value of the phase current detected by the phase current sensor are the same (for example, step in the embodiment) S04, step S06, step S08, step S10, step S12, step S13) and the determination result by the determination means, the sum of the three phases of the phase current is not zero, and the determination result by the phase current determination means When the estimated value and the detected value are different, an abnormality determining means for determining that the phase current sensor related to the phase determined to be different from the estimated value and the detected value is abnormal (for example, an embodiment) Step S05, Step S07, Step S09).

  Furthermore, in the current sensor abnormality detection device for an electric motor of the present invention according to the second aspect of the present invention, the sum of the three phases of the phase current is zero in the determination result by the determination unit, and the phase current determination unit When the estimated value and the detected value are different in the determination result, the DC-side current sensor includes a DC-side abnormality determining unit that determines that the DC-side current sensor is abnormal.

According to the current sensor abnormality detection device for an electric motor according to the first aspect of the present invention, it is possible to quickly detect the presence or absence of abnormality of the phase current sensor.
Furthermore, according to the current sensor abnormality detection device for an electric motor according to the second aspect of the present invention, in addition to the presence / absence of abnormality of the phase current sensor, the presence / absence of abnormality of the DC side current sensor can be quickly detected.

Embodiments of a current sensor abnormality detection device for an electric motor according to the present invention will be described below with reference to the accompanying drawings.
A motor current sensor abnormality detection device 10 (hereinafter simply referred to as a current sensor abnormality detection device 10) according to this embodiment is energized to, for example, a three-phase AC brushless DC motor 11 (hereinafter simply referred to as a motor 11). DC side for detecting DC side current Idc between the presence or absence of abnormality of each phase current sensor 32 for directly detecting each phase current or the negative side terminal of battery 12 as a power source for motor 11 and bridge circuit 13a of inverter 13 The motor 11 detects whether there is an abnormality in the current sensor 31. The motor 11 includes a rotor (not shown) having a permanent magnet used for a field, and a stator that generates a rotating magnetic field that rotates the rotor. (Not shown).
The direct current sensor 31 may be disposed between the bridge circuit 13a of the inverter 13 and the positive terminal of the battery 12.
The current sensor abnormality detection device 10 includes, for example, each phase current sensor 32, a DC side current sensor 31, and a motor control device 14, as shown in FIG.

The three-phase (for example, U-phase, V-phase, and W-phase) AC motor 11 is driven by the inverter 13 in response to a control command output from the motor control device 14.
The inverter 13 includes a bridge circuit 13a formed by bridge connection using a plurality of switching elements (for example, MOSFETs: Metal Oxide Semi-conductor Field Effect Transistors) and a smoothing capacitor C, and the bridge circuit 13a performs pulse width modulation ( It is driven by the PWM signal.

  In this bridge circuit 13a, for example, a high-side and low-side U-phase transistor UH, UL paired for each phase, a high-side and low-side V-phase transistor VH, VL, a high-side and low-side W-phase transistor WH, WL is bridge-connected. Each transistor UH, VH, WH has a drain connected to the positive terminal of the battery 12 to form a high side arm, and each transistor UL, VL, WL has a source connected to the grounded negative terminal of the battery 12. It constitutes the low side arm. For each phase, the sources of the high-side arm transistors UH, VH, WH are connected to the drains of the low-side arm transistors UL, VL, WL, and the transistors UH, UL, VH, VL, WH, WL. Each of the diodes DUH, DUL, DVH, DVL, DWH, DWL is connected between the drain and the source so as to be in the forward direction from the source to the drain.

  The inverter 13 is, for example, a gate signal (that is, a PWM signal) that is a switching command that is output from the motor control device 14 when driving the motor 11 and is input to the gates of the transistors UH, VH, WH, UL, VL, WL. ), The DC power supplied from the battery 12 is converted into the three-phase AC power by switching the on / off (cut-off) state of each pair of transistors for each phase. By sequentially commutating energization to the windings, AC U-phase current Iu, V-phase current Iv and W-phase current Iw are passed through the stator windings of each phase.

  The motor control device 14 performs current feedback control (vector control) on the dq coordinates forming the rotation orthogonal coordinates, calculates the target d-axis current Idc and the target q-axis current Iqc, and calculates the target d-axis current Idc and Each phase voltage command Vu, Vv, Vw is calculated based on the target q-axis current Iqc, and a PWM signal that is a gate signal for the inverter 13 is output according to each phase voltage command Vu, Vv, Vw. The d-axis current Ids and q-axis current Iqs obtained by converting the phase currents Iu, Iv, and Iw supplied from the motor 13 to the motor 11 on the dq coordinate, and the target d-axis current Idc and the target q-axis current Iqc. Control is performed so that each deviation becomes zero.

The motor control device 14 includes, for example, a DC current sensor I / F (interface) 21, a phase current sensor I / F (interface) 22, an overcurrent protection device 23, a phase current estimation unit 24, and a control device 25. The PWM signal generation unit 26 is provided.
The DC side current sensor I / F (interface) 21 is a DC side current sensor 31 that detects the DC side current Idc of the bridge circuit 13a of the inverter 13 between the bridge circuit 13a of the inverter 13 and the negative terminal of the battery 12. The detection signal output from the DC side current sensor 31 is output to the overcurrent protection device 23 and the phase current estimation unit 24.
Note that the DC side current sensor 31 may be disposed between the bridge circuit 13 a of the inverter 13 and the positive terminal of the battery 12.
The phase current sensor I / F (interface) 21 is connected to each phase current sensor 32 that detects each phase current of the three phases between the bridge circuit 13 a of the inverter 13 and the motor 11. The output detection signal is output to the control device 25.
Further, it is output from the angle sensor 33 that detects the rotation angle of the rotor of the motor 11 (that is, the rotation angle of the magnetic pole of the rotor from the predetermined reference rotation position and the rotation position of the rotation shaft of the motor 11). The detection signal is input to the control device 25.
The angle sensor 33 may be omitted, and instead, a device for estimating the magnetic pole position of the rotor of the motor 11 may be provided.

The overcurrent protection device 23 performs a predetermined overcurrent protection operation according to the DC side current Idc detected by the DC side current sensor 31.
The phase current estimation unit 24 actually uses the inverter 13 based on the DC side current Idc detected by the DC side current sensor 31 at the detection timing corresponding to the gate signal (that is, the PWM signal) output from the PWM signal generation unit 26. To estimate the estimated values Iu ^, Iv ^, Iw ^ of each phase current supplied to the motor 11. Details of the operation of the phase current estimation unit 24 will be described later.

The control device 25 converts the phase currents Iu, Iv, and Iw output from the phase current estimation unit 24 into dq coordinates according to the rotation angle of the motor 11 output from the angle sensor 33, and the d-axis obtained. Current feedback control (vector control) is performed so that each deviation between the current Ids and the q-axis current Iqs and the target d-axis current Idc and the target q-axis current Iqc becomes zero, and each phase voltage command Vu, Vv, Vw Is output.
Further, the control device 25 determines each phase current based on the detection signal of the DC side current Idc output from the DC side current sensor 31 and the detection signal of each phase current of the three phases output from each phase current sensor 32. The presence / absence of abnormality of the sensor 32 and the presence / absence of abnormality of the direct current sensor 31 are detected. Details of this abnormality presence / absence detection operation will be described later.

  The PWM signal generator 26 compares each phase voltage command Vu, Vv, Vw with a carrier signal such as a triangular wave in order to pass a sinusoidal current to the three-phase stator winding, and A gate signal (that is, a PWM signal) for driving the transistors UH, VH, WH, UL, VL, WL on / off is generated. Then, the inverter 13 converts the DC power supplied from the battery 12 into three-phase AC power by switching the on (conductive) / off (cut-off) state of each transistor that forms a pair for each of the three phases. By sequentially commutating energization to each stator winding of the three-phase motor 11, AC U-phase current Iu, V-phase current Iv, and W-phase current Iw are energized to each stator winding.

The gate signal input from the PWM signal generation unit 26 to the inverter 13 is, for example, according to the combination of the on / off states of the transistors UH, UL and VH, VL and WH, WL that are paired for each phase. 1 and FIGS. 2A to 2H, the PWM (pulse width) corresponding to each of the eight switching states S1 to S8 (that is, the states of the basic voltage vectors V0 to V7 having different phases by 60 degrees). Modulation) signal. In Table 1 below, the transistors that are turned on among the high-side (High) and low-side (Low) transistors are shown, and the transistors that are turned on in FIGS. Is highlighted.
Then, phase currents Iu, Iv, Iw are intermittently generated on the DC side of the bridge circuit 13a of the inverter 13 according to the switching states S1 to S8, and the DC side current Idc detected by the DC side current sensor 31. Is one of the phase currents Iu, Iv, Iw, or one of the phase currents Iu, Iv, Iw inverted, or zero.

  The phase current estimation unit 24, for example, in each of the switching states S2 to S7 (that is, the states of the basic voltage vectors V1 to V6 having different phases by 60 degrees) in one period of a carrier signal such as a triangular wave. The two-phase phase currents of the three-phase phase currents are acquired from the DC-side current Idc detected by the DC-side current sensor 31 in the two predetermined states. Based on these two-phase phase currents, the other one-phase phase current among the three-phase phase currents is estimated. Then, the estimated values Iu ^, Iv ^, Iw ^ of the three-phase phase currents obtained by estimating from the direct current Idc detected by the direct current sensor 31 are output to the control device 25.

For example, as shown in FIG. 3, in the case of three-phase modulation using a triangular carrier signal, the carrier signal with a voltage pattern symmetrical to the peak (carrier vertex) on the valley side of the triangular carrier signal is obtained. In the period of one cycle Ts, the detected value of each phase current for two phases can be acquired twice.
In other words, the phase current estimation unit 24, in the state of the two basic voltage vectors V1 symmetric with respect to the carrier vertex, times tu1, tu2 that are symmetric with respect to the carrier vertex (that is, the time Ts / of the carrier vertex on the valley side). 2, the first U-phase current Iu1 and the second U-phase current Iu2 are obtained from the DC-side current Idc detected by the DC-side current sensor 31 at a time having the same time interval T1), and further at the carrier apex. In the state of two basic voltage vectors V3 that are symmetrical to each other, times tw1 and tw2 that are symmetric with respect to the carrier vertex (that is, the same time interval T2 with respect to the time Ts / 2 of the carrier vertex on the valley side). The first W-phase current Iw1 and the second W-phase current Iw2 are acquired from the DC-side current Idc detected by the DC-side current sensor 31 at the time).

Then, the phase current estimation unit 24 calculates an average value for each phase based on the phase currents Iu1, Iu2 and Iw1, Iw2, and each average value is a current value at the time Ts / 2 of the carrier apex on the valley side. And
Then, the phase current estimation unit 24 uses the fact that the sum of the current values of the respective phase currents at the same timing is zero, so that the current values of the two-phase currents (for example, the U-phase current and the W-phase current) ( That is, the current value of another one-phase current (for example, V-phase current) is calculated from the current value at the time Ts / 2 of the carrier apex on the valley side.
The phase current estimation unit 24 calculates the average value based on the phase currents Iu1, Iu2 and Iw1, Iw2, and estimates the phase current of the other phase from the two-phase phase current. However, the present invention is not limited to this. Instead, each phase current may be estimated by another estimation method.

The control device 25 determines whether or not the sum of the three-phase phase currents at the same timing (phase current sum = Iu + Iv + Iw) is zero based on the detection signals of the three-phase currents output from the respective phase current sensors 32. Determine whether.
Furthermore, the control device 25 detects the detected values of the three-phase currents output from the respective phase current sensors 32 (that is, the respective phase currents Iu, Iv, Iw) and the three-phases output from the phase current estimation unit 24. It is determined whether or not the estimated values Iu ^, Iv ^, Iw ^ of each phase current are the same.
When the phase current sum is not zero and the detected value and the estimated value of each phase current are different, the phase current sensor 32 related to the phase determined that the detected value and the estimated value are different is abnormal. Judge that there is.
When the phase current sum is zero and the detected value and the estimated value are different, it is determined that the DC-side current sensor 31 is abnormal.

  The current sensor abnormality detection device 10 for an electric motor according to the present embodiment has the above-described configuration. Next, the operation of the current sensor abnormality detection device 10 will be described with reference to the accompanying drawings.

First, in step S01 shown in FIG. 4, the detection value of each phase current (that is, each phase current Iu, Iv, Iw) is acquired from the detection signal output from each phase current sensor 32.
Next, in step S02, estimated values Iu ^, Iv ^, Iw ^ for each phase current are acquired based on the DC current Idc detected by the DC current sensor 31.
In step S03, it is determined whether or not the sum of the phase currents of the three phases at the same timing (phase current sum = Iu + Iv + Iw) is zero.
If this determination is “YES”, the flow proceeds to step S 10 described later.
On the other hand, if this determination is “NO”, the flow proceeds to step S 04 described later.

In step S04, it is determined whether the detected value of the U-phase current (U-phase current Iu) and the estimated value Iu ^ of the U-phase current are the same.
If this determination is “YES”, the flow proceeds to step S 06 described later.
On the other hand, if this determination is “NO”, it is determined that the U-phase phase current sensor (U-phase current sensor) 32 is abnormal, and the flow proceeds to step S 06.

In step S06, it is determined whether or not the detected value of the V-phase current (V-phase current Iv) and the estimated value Iv ^ of the V-phase current are the same.
If this determination is “YES”, the flow proceeds to step S 08 described later.
On the other hand, if this determination is “NO”, it is determined that the V-phase phase current sensor (V-phase current sensor) 32 is abnormal, and the flow proceeds to step S08.

In step S08, it is determined whether the detected value of the W-phase current (W-phase current Iw) and the estimated value Iw ^ of the W-phase current are the same.
If this determination is “YES”, the flow proceeds to the end, and the process ends.
On the other hand, when the determination result is “NO”, the process proceeds to step S09. In step S09, it is determined that the W-phase phase current sensor (W-phase current sensor) 32 is abnormal, and the process proceeds to the end. The process is terminated.

In step S10, it is determined whether the detected value of the U-phase current (U-phase current Iu) and the estimated value Iu ^ of the U-phase current are the same.
If this determination is “YES”, the flow proceeds to step S 12 described later.
On the other hand, when the determination result is “NO”, the process proceeds to step S11. In step S11, it is determined that the DC-side current sensor 31 is abnormal, the process proceeds to the end, and the process ends.

In step S12, it is determined whether or not the detected value of the V-phase current (V-phase current Iv) and the estimated value Iv ^ of the V-phase current are the same.
If this determination is “YES”, the flow proceeds to step S 13 described later.
On the other hand, if this determination is “NO”, the flow proceeds to step S 11 described above, determines that the DC-side current sensor 31 is abnormal, proceeds to the end, and ends the processing.

In step S13, it is determined whether or not the detected value of the W-phase current (W-phase current Iw) and the estimated value Iw ^ of the W-phase current are the same.
If this determination is “YES”, the flow proceeds to the end, and the process ends.
On the other hand, if this determination is “NO”, the flow proceeds to step S 11 described above, determines that the DC-side current sensor 31 is abnormal, proceeds to the end, and ends the processing.

As described above, according to the motor current sensor abnormality detection device 10 according to the present embodiment, the three-phase phases at the same timing are based on the detection signals of the three-phase currents output from the respective phase current sensors 32. It is determined whether or not the sum of the currents (phase current sum = Iu + Iv + Iw) is zero, and further, the detected values of the three-phase currents output from the respective phase current sensors 32 (that is, the respective phase currents Iu, Iv) , Iw) and the estimated values Iu ^, Iv ^, Iw ^ of the three-phase currents output from the phase current estimating unit 24 are the same, Since the presence / absence of abnormality or the presence / absence of abnormality of the DC-side current sensor 31 is detected, a quick and accurate abnormality detection process can be performed.
In addition, since the presence or absence of an abnormality is detected for each phase current sensor 32, the motor according to the detection signal output from each phase current sensor 32 for any two of the three phase current sensors 32. 11, if an abnormality is detected in the phase current sensor 32 used to control the motor 11, another normal phase current sensor 32 is used instead of the phase current sensor 32 in which the abnormality is detected. The control of the motor 11 can be continued properly.

In the above-described embodiment, the phase current estimation unit 24 uses the detected values of the phase currents for two phases in the period of one cycle Ts of the carrier signal for three-phase modulation using a triangular wave carrier signal. An average value is calculated for each phase, and each average value is defined as a current value at the time Ts / 2 at the peak of the carrier on the valley side. However, the present invention is not limited to this. The average value may be calculated for each phase from the detected values of the phase currents for two phases in the period of one cycle Ts, and each average value may be used as the current value at the time Ts / 2 of the carrier peak on the valley side.
The phase current estimation unit 24 calculates the average value for each phase from the detected values of the phase currents for two phases, and estimates the phase current of the other one phase from the phase currents of the two phases. However, the present invention is not limited to this, and each phase current may be estimated by another estimation method.

  In the above-described embodiment, for example, when the time width of each of the switching states S2 to S7 (that is, the state of the basic voltage vectors V1 to V6 having different phases by 60 degrees) is small, that is, when the voltage modulation degree is small or When the phase of the command voltage vector is close to the phase of a single basic voltage vector and there is a possibility that phase current estimation may be difficult, for example, each switching state S2 to S7 (that is, 60 degrees) is performed by a known technique. The time width of the basic voltage vectors V1 to V6 having different phases is increased so that the phase current can be estimated, and whether or not each phase current sensor 32 is abnormal or whether or not the DC current sensor 31 is abnormal May be determined.

It is a block diagram of the electric current sensor abnormality detection apparatus of the electric motor which concerns on embodiment of this invention. It is a figure which shows each switching state S1-S8 of the inverter shown in FIG. It is a figure which shows the example of the detection timing of the on-off pattern and each phase current of the carrier wave and each transistor UH, UL and VH, VL and WH, WL which concern on embodiment of this invention. It is a flowchart which shows operation | movement of the electric current sensor abnormality detection apparatus of the electric motor which concerns on embodiment of this invention.

Explanation of symbols

10 motor current sensor abnormality detection device 11 motor 13 inverter 24 phase current estimation unit 25 control device 26 PWM signal generation unit 31 DC side current sensor 32 phase current sensor step S02 phase current estimation means step S04, step S06, step S08, step S10, Step S12, Step S13 Phase current determining means Step S05, Step S07, Step S09 Abnormality determining means Step S11 DC side abnormality determining means

Claims (2)

An inverter that sequentially commutates energization of a three-phase AC motor by a pulse width modulation signal, a phase current sensor that detects a phase current of the three-phase AC motor,
A DC side current sensor for detecting a DC side current of the inverter; a phase current estimating means for estimating the phase current based on the DC current;
Determining means for determining whether or not the sum of the three phases of the phase current detected by the phase current sensor is zero;
Phase current determining means for determining whether the estimated value of the phase current estimated by the phase current estimating means and the detected value of the phase current detected by the phase current sensor are the same for each phase. When,
When the sum of the three phases of the phase current is not zero in the determination result by the determination means, and the estimated value and the detection value are different in the determination result by the phase current determination means, the estimated value and the detection A current sensor abnormality detection device for an electric motor, comprising: abnormality determination means for determining that the phase current sensor relating to a phase determined to have a different value is abnormal. When the sum of the three phases of the phase current is zero in the determination result by the determination means, and the estimated value and the detected value are different in the determination result by the phase current determination means, the DC-side current sensor is The current sensor abnormality detection device for an electric motor according to claim 1, further comprising a DC-side abnormality determination unit that determines that there is an abnormality.

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