JP2012005199A - Motor controller, compressor and heat pump device - Google Patents

Abstract

Provided is a motor control device capable of compensating for torque fluctuation so as to coincide with an actual load torque fluctuation mode.
A speed control unit outputs a d-axis current command value Idref and a q-axis current command value Iqref so that a rotation speed of a motor 4 coincides with a speed command ωref given from outside, and the current control unit 21 The d-axis voltage command Vd and the q-axis voltage command value Vq are output so that the d-axis current Id and the q-axis current Iq match the above commands. The correction unit 24 multiplies the reference load torque T by a ratio α between the reference load torque average value T_ave and the average q-axis current command value Iq_ave, and subtracts the q-axis current command value Iqref from the multiplied value. The multiplied value is superimposed on the q-axis current command value Iqref as the q-axis current correction value Iq_cor.
[Selection] Figure 1

Description

  Embodiments described herein relate generally to a motor control device, a compressor, and a heat pump device that drive a load whose torque varies periodically.

For example, a refrigeration cycle used for a refrigerator, an air conditioner, a heat pump hot water supply device, etc. is composed of a compressor, a condenser, a decompressor, an evaporator, and the like. A compressor is used. In the control of the rotational speed of the motor used in such a compressor, feedback control is performed so as to output a control amount corresponding to the deviation between the target rotational speed and the actual rotational speed of the motor. In the conventional feedback control, the target rotation speed and the actual rotation speed are matched by controlling the applied voltage a plurality of times during one rotation of the motor.

However, since the compressor has a large variation in load torque during one rotation, it is difficult to remove the torque variation by simple feedback control as described above, and the entire compressor vibrates in the rotational direction of the motor. There is a problem that it becomes a source of vibration and noise of a refrigerator, an air conditioner or the like equipped with this, and impairs the merchantability.

In order to solve such a problem, Patent Document 1 discloses a technique for compensating for fluctuations in load torque by adding a sinusoidal current as a current correction value to a q-axis current obtained by vector control of a motor. It is disclosed.

JP 2001-183017 A

  However, although the technique of Patent Document 1 can suppress vibration to some extent, there is a problem in that efficiency is lowered because an extra current flows. In addition, the variation mode of the load torque is not completely coincident with the sine wave, so that there is a limit to the level for suppressing vibration and the like. Furthermore, the correction by the sine wave is effective only under certain conditions, and when the load torque changes, the level for suppressing vibration and the like deteriorates.

  Embodiments of the present invention have been made in view of the above circumstances, and an object of the present invention is to provide a motor control device that can compensate for torque fluctuations so as to coincide with actual load torque fluctuation modes. It is in.

  To achieve the above object, a motor control device according to an embodiment of the present invention is a motor control device that drives a load whose torque fluctuates periodically, and detects a current flowing through a winding of the motor. Detection means; calculation means for obtaining a d-axis current value as an excitation component current and a q-axis current value as a torque component current based on the current; and a rotational speed of the motor matches a speed command given from outside. The speed control means for generating the d-axis current command value and the q-axis current command value, the reference load torque storage unit for storing the reference load torque for each rotation angle of the motor, and the average value of the q-axis current command value An average q-axis current command value calculation unit for calculating a certain average q-axis current command value; a ratio calculation unit for calculating a ratio between the average value of the reference load torque and the average q-axis current command value; and Reference load A load torque correction unit that calculates a load torque correction value by multiplying the torque, a reference correction torque calculation unit that calculates a reference correction torque by subtracting the load torque correction value and the q-axis current command value, and the reference A correction torque adjusting unit that calculates a q-axis current correction value by multiplying the correction torque by a predetermined gain, and superimposing the q-axis current correction value on the q-axis current command value.

1 is a functional block diagram showing a configuration of a motor control device according to Embodiment 1 of the present invention. Diagram showing heat pump cycle of air conditioner Torque controller flowchart Functional block diagram showing the configuration of the motor control device according to the second embodiment of the present invention. Functional block diagram showing a configuration of a motor control device according to another embodiment of the present invention.

Example 1
Hereinafter, an embodiment of driving a motor of a compressor of an air conditioner as an example of a heat pump device will be described with reference to the drawings. In FIG. 2, the compressor (load) 2 constituting the heat pump device 1 is configured by accommodating the compression unit 3 and the motor 4 in the same iron hermetic container 5, and the rotor shaft of the motor 4 is connected to the compression unit 3. Has been. The compressor 2, the four-way valve 6, the indoor heat exchanger 7, the pressure reducing device 8, and the outdoor heat exchanger 9 are connected by a pipe serving as a heat transfer medium flow path so as to form a closed loop. The compressor 2 is, for example, a rotary compressor, and the motor 4 is, for example, a three-phase IPM (Interior Permanent Magnet) motor.

At the time of heating, the four-way valve 6 is in a state indicated by a solid line, and the high-temperature refrigerant compressed by the compression unit 3 of the compressor 2 is supplied from the four-way valve 6 to the indoor heat exchanger 7 to be condensed, and then the decompression device. The pressure is reduced at 8 and the temperature becomes low and flows to the outdoor heat exchanger 9 where it evaporates and returns to the compressor 2. On the other hand, at the time of cooling, the four-way valve 6 is switched to a state indicated by a broken line. For this reason, the high-temperature refrigerant | coolant compressed with the compression part 3 of the compressor 2 is supplied to the outdoor side heat exchanger 9 from the four-way valve 6, is condensed, and is decompressed by the decompression device 8, and becomes low temperature indoor side It flows into the heat exchanger 7, where it evaporates and returns to the compressor 2. The indoor and outdoor heat exchangers 7 and 9 are blown by the fans 10 and 11, respectively, and the heat exchange between the heat exchangers 7 and 9 and the indoor air and outdoor air is efficient. It is structured to be performed well.

  FIG. 1 is a block diagram showing the configuration of a motor control device 20 that performs vector control of the rotation of the motor 4. In the vector control, the current flowing through the armature winding is separated into the magnetic flux direction of the permanent magnet, which is a field, and the direction orthogonal thereto, and these are adjusted independently to control the magnetic flux and the generated torque. For the current control, a current value represented by a coordinate system that rotates with the rotor of the motor 4, that is, a so-called dq coordinate system, is used, and the d-axis is the direction of magnetic flux created by a permanent magnet attached to the rotor, and q The axis is a direction orthogonal to the d-axis. The q-axis current Iq that is the q-axis component of the current flowing through the winding is a component that generates rotational torque (torque component current), and the d-axis current Id that is the d-axis component is a component that generates magnetic flux (excitation or Magnetization component current).

  The motor control device 20 includes a current control unit 21, a rotational position estimation unit 22, a speed control unit 23, and a correction unit 24.

The current control unit 21 includes subtractors 31d and 31q, proportional-integral differentiators 32d and 32q, dq / αβ coordinate converter 33, αβ / UVW coordinate converter 34, UVW / αβ coordinate converter 35, αβ / dq coordinate converter. 36.

  The current sensor 37 (U, V, W) is a sensor that detects currents Iu, Iv, and Iw that flow in each phase (U phase, V phase, and W phase) of the motor 4. Instead of the current sensor 37, three shunt resistors are arranged between the lower arm side switching element constituting the inverter circuit 38 and the ground, and the currents Iu, Iv, Iw are detected based on the terminal voltages thereof. It is good also as composition to do.

  The currents Iu, Iv, Iw detected by the current sensor 37 are converted into two-phase currents Iα, Iβ by the UVW / αβ coordinate converter 35, and these two-phase currents Iα, Iβ are converted into an αβ / dq coordinate converter 36. Is converted into a d-axis current Id and a q-axis current Iq. α and β are coordinate axes of a biaxial coordinate system fixed to the stator of the motor 4. For the calculation of the coordinate transformation in the αβ / dq coordinate converter 36, a rotational position estimated value (estimated value of the phase difference between the α axis and the d axis) θe described later is used.

  The subtractor 31d subtracts the d-axis current Id from the d-axis current command value Idref to calculate a d-axis current deviation ΔId. The subtractor 31q calculates a q-axis current deviation ΔIq by subtracting the q-axis current Iq from the q-axis current command value Iqref and further adding a q-axis current correction value Iq_cor input from a correction unit described later.

  The proportional-integral differentiators 32d and 32e perform a proportional-integral-derivative operation on the d-axis current deviation ΔId and the q-axis current deviation ΔIq to obtain the d-axis voltage command value Vd and the q-axis voltage command value Vq expressed in the dq coordinate system. Generate.

  The d-axis voltage command value Vd and the q-axis voltage command value Vq are converted into values expressed in the α-β coordinate system by the dq / αβ coordinate converter 33, and each phase of the stator is further converted by the αβ / UVW coordinate converter 34. It is converted into voltage command values Vu, Vv, Vw. Note that the rotation position estimation value θe of the rotor, which will be described later, is used for the coordinate conversion calculation in the dq / αβ coordinate converter 33.

  The phase voltage command values Vu, Vv, and Vw are input to the PWM forming unit 25, and a pulse drive modulated gate drive signal for supplying a voltage that matches the command value is formed. The inverter circuit 38 is configured by connecting switching elements such as IGBTs in a three-phase bridge, and is supplied with a DC voltage from a DC power supply circuit (not shown). The gate drive signal formed by the PWM forming unit 25 is given to the gate of each switching element constituting the inverter unit 38, and thereby PWM-modulated three-phase alternating current that matches each phase voltage command value Vu, Vv, Vw. A voltage is generated and applied to the armature winding of the motor 4.

  In the above configuration, feedback control is performed by proportional-integral-derivative (PID) calculation by the subtractors 31d, 31q and the proportional-integral-differentiator 32d, 32q, and the d-axis current Id and the q-axis current Iq are respectively d-axis current command values. It is controlled so as to coincide with Idref and q-axis current command value Iqref.

  The rotational position estimation unit 22 estimates an estimated value θe of the rotational position θ of the rotor and an estimated value ωe of the rotational speed ω, and includes a d-axis current Id, a q-axis current Iq, and a d-axis voltage command value Vd, Is entered. Further, the rotational position estimation unit 22 stores values of d-axis inductance Ld, q-axis inductance Lq, and winding resistance value R of the armature winding, which are circuit constants of the motor 4.

  Using these input values and circuit constants, the rotational position estimation unit 22 calculates an induced voltage estimated value Ed in the d-axis direction using the following equation.

Ed = Vd-R.Id-Ld.p.Id + .omega.e.Lq.Iq (1)
Here, p is a differential operator. The induced voltage estimated value Ed is subjected to proportional-integral calculation, and the result is output as the rotor rotational speed estimated value ωe. Further, by integrating the estimated rotational speed value ωe, the value is output as the estimated rotational position value θe. Further, the estimated rotational speed value ωe is also given to the speed control unit 23. The rotational position estimation is not limited to the above method, and various methods such as calculation by inputting the q-axis voltage command value Vq can also be adopted.

  The speed control unit 23 is a circuit that outputs a d-axis current command value Idref and a q-axis current command value Iqref. The d-axis current command value Idref and the q-axis current command value Iqref are current command values for making the rotational speed ωe of the rotor coincide with the rotational speed command value ωref input from the outside. The speed controller 23 includes a subtracter 39 and a dq distributor 40.

  The subtractor 39 calculates a deviation Δω between the rotational speed command value ωref output from an external microcomputer (not shown) that controls the operation of the air conditioner and the rotational speed estimated value ωe. The deviation Δω is subjected to proportional-integral-derivative calculation by a proportional-integral-differentiator 41 built in the dq distributor 40, and the calculation result is distributed to the d-axis current command value Idref and the q-axis current command value Iqerf and output. . Various methods can be adopted as the distribution method. For example, the value obtained by proportionally integrating and differentiating the deviation Δω is Iqref, and the value of Idref is 0.

  Then, the d-axis current command value Idref and the q-axis current command value Iqref are given to the current control unit 21, and the d-axis current Id and the q-axis current Iq of the motor 4 coincide with these command values Idref and Iqref as described above. To be controlled. The estimated rotation speed value ωe as the control result is fed back to the subtractor 39. The proportional integral differentiator 41 converges the deviation Δω to zero by proportional integral differential calculation. As a result, the estimated rotational speed value ωe becomes equal to the rotational speed command value ωref.

  The correction unit 25 includes a reference load torque storage unit 43, an average q-axis current command value calculation unit 44, a ratio calculation unit 46, a load torque correction unit 47, a reference correction torque calculation unit 48, and a correction torque adjustment unit 49. .

  The reference load torque storage unit 43 is a microcomputer or the like that stores a reference load torque (hereinafter referred to as “reference load torque T”) in a data table for each angle of the motor 4. As the reference load torque T, data obtained in advance by experiment or simulation of a load torque generated by driving the compressor at a rotation speed at which vibration causes a problem is used. A plurality of load torque tables may be prepared, and the reference load torque T may be properly used according to the use conditions. The use conditions are, for example, the difference in the use such as the magnitude of the rotation speed and the cooling / heating, and the plurality of load torque tables corresponding to the use conditions are prepared. In addition, since an error may occur in the angle of the motor 4 when the estimated value is used, the reference load torque T may be corrected to a constant value or a sine wave shape regardless of the angle of the motor 4. The reference load torque storage unit 43 outputs the reference load torque T to the load torque correction unit 47. The reference load torque storage unit 43 calculates a reference load torque average value T_ave, which is an average value, and outputs the average value to the ratio calculation unit. The reference load torque average value T_ave may be stored in advance in a microcomputer and output to the proportional calculation unit.

  The average q-axis current command value calculation unit 44 calculates an average q-axis current command value Iqref_a that is an average value of the q-axis current command value Iqref, and outputs it to the ratio calculation unit 46.

  The ratio calculation unit 46 calculates the ratio α by dividing the reference load torque average value T_ave from the average q-axis current command value Iqref_a and outputs the ratio α to the load torque correction unit 47.

  The load torque correction unit 47 calculates the load torque correction value Tα by multiplying the input reference load torque T and the ratio α, and outputs the load torque correction value Tα to the reference correction torque calculation unit 48. For example, when the ratio between the average q-axis current command value Iqref_a and the reference load torque average value T_ave is 1.2, the load torque correction value Tα is a value obtained by multiplying the reference load torque T by 1.2 for each call. Become.

  The reference correction torque calculation unit 48 calculates the reference correction torque T_base by subtracting the q-axis current command value Iqref from the load torque correction value Tα, and outputs it to the correction torque adjustment unit 49.

  The correction torque adjustment unit 49 calculates a q-axis current correction value Iq_cor by multiplying the reference correction torque T_base by a predetermined gain G, and outputs the q-axis current correction value Iq_cor to the subtractor 31q. The predetermined gain G can be set in various ways, for example, according to the number of rotations. Specifically, since the vibration decreases as the rotational speed increases, the gain G is set to be inversely proportional to the rotational speed. When the specified rotational speed is reached, the gain G becomes zero and torque control is not performed. The gain G is determined by experiment or simulation.

  The subtractor 31q calculates the q-axis current deviation ΔIq by subtracting the q-axis current Iq from the q-axis current command value Iqref and further adding the q-axis current correction value Iq_cor.

Next, the operation of this embodiment will be described with reference to FIG.

FIG. 3 is a flowchart mainly showing the processing contents. First, when a rotational speed command is given to the motor 4 and the motor 4 is started by, for example, forced commutation (step S1), the process waits until the rotation of the motor 4 reaches a steady state (step S2).

Then, angle information is acquired (step S3), and a q-axis current correction value (step S4) is superimposed according to the speed or the fluctuation range of the estimated speed. While the motor 4 is in operation, the above process is repeated.

As described above, according to the present embodiment, by calculating the correction torque as described above, the motor can be controlled by compensating for the torque fluctuation so as to coincide with the actual load torque fluctuation mode. Therefore, it is possible to suppress the vibration and noise of the motor having a large load fluctuation and to improve the driving efficiency.

In addition, since the control to be corrected can be calculated and adjusted on the microcomputer, torque fluctuation can be compensated accurately and easily.

  Further, according to the system of the present embodiment, the reference load torque T is multiplied by the value of the ratio α between the reference load torque average value T_ave and the average q-axis current command value Iqref_a, thereby storing the reference load torque stored in advance. The value of T can be varied according to the magnitude of the q-axis current command value Iqref, and an appropriate load torque correction value Tα corresponding to the q-axis current command value Iqref can be calculated.

  Further, according to the method of the present embodiment, the q-axis current correction value Iq_cor is generated based on the value obtained by subtracting the q-axis current command value Iqref from the load torque correction value Tα, so that the q calculated by the subtractor 31q. The higher-order component superimposed on the q-axis current command value Iqref is canceled in the shaft current deviation ΔIq, and the vibration and noise of the motor can be reduced.

(Example 2)
A second embodiment will be described with reference to FIG. In addition, description is abbreviate | omitted about the part same as Example 1 mentioned above, and only a different part is demonstrated.

  The correction unit 26 includes a reference load torque storage unit 43, an average q-axis current command value calculation unit 44, a ratio calculation unit 46, a load torque correction unit 47, a reference correction torque calculation unit 48, a rotation speed fluctuation range calculation unit 50, and a correction torque. An adjustment unit 51 is provided.

  The rotation speed fluctuation range calculation unit 49 calculates the fluctuation range of the rotation speed ωe output from the rotation position estimation unit 22. In addition, when noise is included in the range of fluctuations in the rotational speed, averaging may be performed by applying a filter. The rotation speed fluctuation range calculation unit 49 stores the rotation speed fluctuation width at a plurality of points in the past, and torque control that minimizes the rotation speed fluctuation width depending on whether the fluctuation width is decreasing or increasing. The gain G_t is determined. For example, in the change in the rotational speed fluctuation range at a plurality of points, the torque control gain G_t is increased when the fluctuation range is decreasing, and the torque control gain G_t is decreased when the fluctuation range is increasing. Here, there are various determination methods for the tendency of the fluctuation range to decrease / increase, and the user can arbitrarily set the determination means. For example, the tendency of the fluctuation width to decrease means that the fluctuation width sampled within a predetermined time is more decreased than the previous fluctuation width. On the other hand, the fluctuation trend is increasing when the fluctuation width sampled within a predetermined time is more increased than the previous fluctuation width. As another example, various methods such as determining a decrease / increase tendency as a case where the sampled fluctuation range value is decreased / increased compared to the previous fluctuation range value can be adopted. . Thereby, the reference load torque T can be varied based on the information on the fluctuation range of the rotation speed, and the value of the torque control gain G_t can be adjusted so that the fluctuation of the rotation speed is minimized. For example, when the load torque increases, the fluctuation range tends to increase even if the torque control gain G_t is decreased. In order to avoid this state, if the rotational speed has increased even if the torque control gain is continuously decreased a plurality of times, the torque control gain G_t is increased a plurality of times. After increasing the torque control gain G_t a plurality of times, the torque control gain G_t is set corresponding to the increasing / decreasing trend of the fluctuation range as usual.

  The correction torque adjusting unit 51 calculates the q-axis current correction value Iq_cor by multiplying the control gain G based on the torque control gain G_t and the reference correction torque T_base, and outputs the q-axis current correction value Iq_cor to the subtractor 31q.

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained.

  Further, by calculating the q-axis current correction value Iq_cor in this way, the q-axis current correction value Iq_cor can be determined so as to minimize the fluctuation in the rotational speed, and the balance between the load torque and the motor output torque can be maintained. The vibration of the compressor can be reduced.

(Other examples)
The present invention is not limited to the embodiments described above and shown in the drawings. For example, the following modifications or expansions are possible.

  Although the air conditioner has been exemplified as the heat pump device, the present invention is not limited thereto, and various applications such as a refrigerator and a heat pump hot water heater can be applied. Furthermore, the present invention is not limited to the compressor and can be applied to any load having a characteristic that the torque varies periodically.

  Further, the present invention is not limited to a rotary type compressor, and may be applied to a reciprocating type compressor.

  Further, the speed or the fluctuation range of the estimated speed may be an average value in a plurality of rotations instead of once. The correction period may be every multiple rotations instead of every rotation. An average value may be used as the load torque for each operating condition (speed).

  Further, as a method of detecting the rotational position of the motor, a method of detecting the rotational position of the motor with a sensor such as an encoder may be adopted instead of the rotational position estimation unit.

  Further, when the motor efficiency is prioritized over the compressor vibration, the correction torque or the q-axis current may be limited. In this case, as shown in FIG. 5, when the maximum value of the q-axis current or the motor current reaches a specified value, the increase of the torque control gain G_t is suppressed or the value of the q-axis current is not increased beyond a specified value. You may further have the correction torque amount adjustment part which makes it. The specified value may be changed according to the rotational speed.

  In the drawings, 2 is a compressor, 4 is a motor, 20 is a motor control device, 21 is a current control unit, 22 is a rotational position estimation unit, 23 is a speed control unit, 24 and 26 are correction units, and 31d and 31q are subtractors. 32d and 32q are proportional integral differentiators, 37 are current sensors, 40 is a speed control unit, 41 is a proportional integral integral differentiator, 43 is a reference load torque storage unit, 44 is an average q-axis current command value calculation unit, and 46 is a ratio. A calculation unit, 47 is a load torque correction unit, 48 is a reference correction torque calculation unit, 49 and 51 are correction torque adjustment unit torque control units, and 50 is a rotation speed fluctuation range calculation unit.

Claims (7)

A motor control device for driving a load whose torque varies periodically,
Current detection means for detecting a current flowing in the winding of the motor;
Calculating means for obtaining a d-axis current value as an excitation component current and a q-axis current value as a torque component current based on the current;
Speed control means for generating a d-axis current command value and a q-axis current command value so that the rotational speed of the motor matches a speed command given from outside;
A reference load torque storage unit for storing a reference load torque for each rotation angle of the motor;
an average q-axis current command value calculation unit for calculating an average q-axis current command value that is an average value of the q-axis current command values;
A ratio calculator that calculates a ratio between the average value of the reference load torque and the average q-axis current command value;
A load torque correction unit that calculates a load torque correction value by multiplying the reference load torque by the ratio;
A reference correction torque calculator that calculates a reference correction torque by subtracting the load torque correction value and the q-axis current command value;
A correction torque adjusting unit that calculates a q-axis current correction value by multiplying the reference correction torque by a predetermined gain;
The motor control device, wherein the q-axis current correction value is superimposed on the q-axis current command value. A rotation speed fluctuation calculating section for calculating a fluctuation width of the rotation speed of the motor and calculating a torque control gain so as to minimize the fluctuation width;
The correction torque adjusting unit calculates a q-axis current correction value by multiplying the reference correction torque by a gain based on the torque control gain. 3. The motor control according to claim 1, wherein the load torque storage unit stores a plurality of torque patterns, and selects the torque pattern according to a use condition of the motor as a reference load torque. 4. apparatus. The correction torque adjustment unit further includes a correction torque amount adjustment unit that adjusts the q-axis current correction value or the q-axis current command value according to a parameter related to the rotational speed or efficiency of the motor. 4. The motor control device according to any one of 3. 5. The motor control device according to claim 1, wherein the load torque storage unit is corrected to a constant value or a sine wave regardless of a rotation angle of the motor. A motor,
The motor control device according to any one of claims 1 to 5, which performs rotation drive control of the motor;
A compressor having a compression unit connected to the motor and compressing a heat transfer medium by rotational driving of the motor. Comprising a heat pump in which a compressor, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger are connected by a heat transfer medium flow path;
A motor for driving the compressor is controlled by the motor control device according to any one of claims 1 to 5.

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