JP2012050173A - Ac motor drive control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive control apparatus capable of controlling AC motor drive seamlessly without changing control modes.SOLUTION: A reference voltage signal Van which is the control object is corrected as the added signal of a sinusoidal signal and a square wave signal, with the degree of the square wave adjusted by an angle parameter Delta. The corrected reference voltage signal is changed from a sinusoidal signal to a square wave signal by changing Delta continuously from 0 to 60. The flux locus is changed continuously from a circle to a hexagon by driving an inverter with a PWM-modulated wave of the corrected reference voltage signal.

Description

  The present invention relates to seamless single mode control of an AC motor (AC motor).

  There is known a configuration in which an AC motor as a drive source mounted on a hybrid vehicle or an electric vehicle is driven and controlled by appropriately switching a control mode. For example, there are a method for switching between two control modes or a method for switching between three control modes. In the method of switching between the two control modes, normal PWM control is performed in the low rotation range, and rectangular wave control is performed in the high rotation range. In the method of switching between the three control modes, an overmodulation control mode is used in addition to these control modes. The sine wave control mode with a modulation rate of 1 or less, the overmodulation control mode with a modulation rate exceeding 1 and the rectangular wave control mode are sequentially switched from the region where the rotation speed and torque are small.

  18A to 18C schematically show these three control modes. In the sine wave control mode of FIG. 18A, a sine wave output voltage command value is generated with an amplitude equal to or smaller than the amplitude of the triangular wave in the PWM control by the triangular wave comparison, and converted into a PWM signal. In the overmodulation control mode of FIG. 18B, a sinusoidal output voltage command value is generated with an amplitude exceeding the amplitude of the triangular wave and converted into a PWM signal. In the rectangular wave control mode shown in FIG. 18C, a rectangular wave signal having a high-level period / low-level period ratio of 1: 1 is generated. In the low rotation low torque region, the sine wave control mode is used to control the electric motor with good responsiveness, and smooth rotation can be obtained even in the low rotation region. In addition, by using the rectangular wave control mode in the high-rotation high-torque region, the voltage utilization factor of the DC power supply is improved, the output in the high-rotation region is improved, and the occurrence of copper loss and switching loss are suppressed, resulting in energy efficiency. Can be improved (see Patent Documents 1 and 2). These three control modes are sequentially switched according to the rotation speed and the output torque while referring to a control mode setting map stored in a memory prepared in advance.

JP 2009-165326 A JP 2008-253000 A

  However, the method for switching the three control modes according to the rotational speed and the output torque requires a relatively complicated device configuration for realizing this. Further, there is a possibility that torque fluctuation occurs when the control mode is switched from one control mode to the next control mode.

  In addition, space vector modulation (SPM) has also been proposed as drive control for AC motors, but complex equations must be solved in real time to generate the reference voltage, or depend on more motor parameters. There are problems such as.

  An object of the present invention is to provide a drive control device capable of seamlessly driving and controlling an AC motor without switching control modes.

  The present invention relates to a drive control device for an AC motor, and generates a reference voltage signal that is a control target, and the reference voltage signal from the generator is a sine wave signal according to the speed of the AC motor. A correction means for correcting and outputting as a signal obtained by adding a rectangular wave signal; and a modulation means for PWM-modulating the reference voltage signal corrected by the correction means and supplying the reference voltage signal to the switching element of the inverter. Control is performed in a single control mode using a voltage signal.

  In one embodiment of the present invention, there is provided means for calculating an angle parameter Delta (where 0 ≦ Delta ≦ 60) whose value increases as the speed or torque of the AC motor increases in accordance with the speed or torque of the AC motor. And the correction means uses the angle parameter Delta and sets the reference voltage signal so that the sine wave region and the rectangular wave region appear alternately, with the Delta region as a sine wave signal and the 60-Delta region as a rectangular wave region. Correct it.

In another embodiment of the present invention, the correcting means sets the three-phase reference voltage signals from the generating means to Van, Vbn, and Vcn, respectively.
Voltage ^{Vm = {Van 2 + (Vbn} -Vcn) 2/3} 1/2
And the absolute values Abs of Van, Vbn, and Vcn are as follows:
Vm · sin (π / 6−Delta / 2) ≦ Abs ≦ Vm · sin (π / 6 + Delta / 2)
Means for replacing the sine wave signal with the rectangular wave signal having the voltage value Vm as an amplitude when satisfying,
Abs> Vm · sin (π / 2-Delta / 2)
And a means for replacing the sine wave signal with the rectangular wave signal having the voltage value Vm as an amplitude when the condition is satisfied.

  In another embodiment of the present invention, the generating unit generates the reference voltage signal by either scalar control or vector control. That is, the present invention can be applied to any control method regardless of scalar control or vector control.

  According to the present invention, the AC motor can be driven and controlled seamlessly without switching the control mode. Therefore, according to the present invention, it is possible to prevent torque fluctuation due to switching of the control mode.

It is a basic system block diagram of an embodiment. It is change explanatory drawing of the magnetic flux locus | trajectory according to a motor speed. It is reference voltage signal Vab and magnetic flux locus explanatory drawing. It is reference voltage signal Van and magnetic flux locus explanatory drawing. It is a waveform explanatory view of the reference voltage signal Van. It is a block diagram of the conventional PWM modulator. It is a block diagram of the corrected PWM modulator. It is a calculation processing flowchart of a reference voltage signal calculator. It is a system block diagram of the drive control apparatus of scalar control. It is a system block diagram of the drive control apparatus of vector control. It is waveform explanatory drawing of Van, Vbn, and Vcn. It is a wave explanatory drawing of Van and a PWM modulation signal. It is waveform explanatory drawing of Vab and a PWM modulation signal. It is waveform explanatory drawing of the PWM modulation signal of Vab, Vbc, and Vca. It is magnetic flux locus | trajectory explanatory drawing in Delta = 0. It is magnetic flux locus | trajectory explanatory drawing in Delta = 30. It is magnetic flux locus explanatory drawing in Delta = 60. It is switching explanatory drawing of the conventional control mode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a basic system configuration diagram in the present embodiment. The system includes a battery 1, a boost converter 2 connected to the battery 1, an inverter 3 connected to the boost converter 2, and an AC motor 4 connected to the inverter 3. The inverter 3 is composed of two switching transistors in which three phases are connected in series. Control signals are supplied to the gate terminals of a total of six switching transistors of the inverter 3 to convert the DC voltage to drive and control the AC motor 4.

  When the AC motor 4 is driven and controlled, as described above, when the control is sequentially switched from the sine wave control to the rectangular wave control, torque fluctuation occurs when the control mode is switched. In order to suppress torque fluctuations, it is necessary to seamlessly transition control from sine wave control to rectangular wave control.

  2 (a) to (f), reference voltage signal (output voltage command value) in sine wave control, PWM modulation signal and corresponding magnetic flux corresponding thereto, reference voltage signal (output voltage command value) in rectangular wave control, The PWM modulation signal corresponding to this and the generated magnetic flux are shown.

  FIG. 2A shows a reference voltage signal (output voltage command value) in the limit wave control. When the three phases are the a-phase, b-phase, and c-phase, respectively, the voltage signals VabRef, VbcRef, and VcaRef between the phases are expressed as follows. Show. Here, for example, VabRef indicates a reference voltage signal between the a phase and the b phase.

  FIG. 2B shows a PWM modulation signal after PWM modulation is performed by comparing each reference voltage signal shown in FIG. 2A with a triangular wave. FIG. 2C shows a magnetic flux when the inverter 3 is subjected to switching control with the PWM modulation signal shown in FIG. There are eight types of voltage vectors depending on the combination of switching modes of the inverter 3 (on / off of each switch of a phase (or u phase), b phase (or v phase), c phase (or w phase)). That is, v0 (000), v1 (100), v2 (110), v3 (010), v4 (011), v5 (001), v6 (101), and v7 (111). Among these, v0 (000) and v7 (111) are zero vectors, and the others are non-zero vectors. The magnetic flux vector is expressed as an integral of the voltage vector. If the voltage drop is small, the magnetic flux trajectory points toward the inverter voltage vector. When the output of the inverter 3 is one of non-zero vectors, the magnetic flux moves at a speed proportional to the output voltage. In the case of a zero vector, the moving speed is very small and can be regarded as approximately zero. Therefore, by appropriately selecting the voltage vector, the magnetic flux moves along a specific trajectory. The inverter voltage vector changes periodically in steps of π / 3. When the reference voltage signal is a sine wave signal, the locus of the magnetic flux is circular on the dq plane composed of the d axis and the q axis.

  On the other hand, FIG. 2D is a reference voltage signal (output voltage command value) in rectangular wave control, and voltage signals VabRef and VbcRef between the phases when the three phases are the a phase, b phase, and c phase, respectively. , VcaRef.

  FIG. 2E shows a PWM modulation signal after PWM modulation is performed by comparing each reference voltage signal shown in FIG. 2D with a triangular wave. FIG. 2F shows the magnetic flux when the inverter 3 is switching-controlled with the PWM modulation signal shown in FIG. When the reference voltage signal is a rectangular wave signal, the locus of the magnetic flux is a hexagon in the dq plane.

  Thus, when the reference voltage signal is a sine wave, the magnetic flux locus is circular, and when the reference voltage signal is a rectangular wave signal, the magnetic flux locus is hexagonal. Therefore, assuming an added reference voltage signal obtained by adding a limit wave and a rectangular wave as the reference voltage signal, the magnetic flux locus generated by the new reference voltage signal obtained by the addition is a combination of a circle and a hexagon. That is, as a new reference voltage signal, a signal in which a sine wave region and a rectangular wave region exist alternately, the magnetic flux trajectory includes a circular region corresponding to the sine wave and a hexagonal region corresponding to the rectangular wave. Appears alternately.

  FIG. 3 shows a locus of magnetic flux when a sine wave signal and a rectangular wave signal are added, taking VabRef as an example of the reference voltage signal. FIG. 3A shows a rectangular-wave reference voltage signal, and FIG. 3B shows a PWM modulation signal corresponding thereto. FIG. 3C shows a sinusoidal reference voltage signal, and FIG. 3D shows a PWM modulation signal corresponding thereto. FIG. 3E shows a locus of magnetic flux generated by a signal obtained by adding these two signals (sine wave signal + rectangular wave signal). In the rectangular wave signal portion, a linear locus reflecting a hexagonal locus as shown in FIG. On the other hand, the sine wave signal portion has an arcuate locus reflecting a circular locus as shown in FIG. Accordingly, if the angle parameter that defines the rectangular wave signal region is Delta and the angle parameter that defines the sine wave signal region is 60-Delta, a linear locus is formed at the Delta angle, and a circle is formed at the 60-Delta angle. It becomes an arc-shaped trajectory. In the area of the rectangular wave signal, the inverter voltage vector is maintained without being switched, resulting in a hexagonal shape. Therefore, it can be said that Delta is a parameter that defines the non-switching area of the inverter voltage vector.

  In the figure, the magnetic flux locus portion generated by the rectangular wave signal is indicated as “Square Wave”, and the magnetic flux locus portion generated by the sine wave signal is indicated as “Sin Wave”. By continuously changing Delta from 0 degree to 60 degrees, the reference voltage signal is continuously changed from a sine wave signal to a rectangular wave signal, and accordingly, the magnetic flux trajectory continues from a circle to a hexagon. Will change.

  FIG. 4 shows an example of the a-phase reference voltage signal. FIG. 4A shows an a-phase reference voltage signal, which is an added reference voltage signal obtained by adding a sine wave signal and a rectangular wave signal. FIG. 4B shows a PWM modulation signal corresponding to this. FIG. 4C shows a locus of magnetic flux generated by the added reference voltage signal. Assuming that the angle occupied by the rectangular wave signal is Delta degrees and the portion occupied by the sine wave signal component is 60-Delta degrees, a linear locus is formed at the Delta angle, and an arc-shaped locus is formed at the 60-Delta angle. In the figure, the magnetic flux locus portion generated by the rectangular wave signal is indicated as “Square Wave”, and the magnetic flux locus portion generated by the sine wave signal is indicated as “Sin Wave”. By continuously changing Delta from 0 degree to 60 degrees, the reference voltage signal is continuously changed from a sine wave signal to a rectangular wave signal, and accordingly, the magnetic flux trajectory continues from a circle to a hexagon. Will change.

  FIG. 5 shows in more detail the waveform of the a-phase reference voltage signal. It is generated by adding a sine wave signal and a rectangular wave signal. Assuming that the angle occupied by the rectangular wave signal is Delta degrees and the portion occupied by the sine wave signal component is 60-Delta degrees, the rectangular wave area and the sine wave area appear alternately. In order from 0 degree, the range from 0 degree to (60-Delta) / 2 degrees is a sine wave region, the next Delta degree is a rectangular wave region, and the next 60 to Delta degree is a sine wave. This is a region, and thereafter, a rectangular wave region is formed during the Delta degree. This is repeated thereafter. The same applies to the b-phase and c-phase reference voltage signals. By continuously changing Delta from 0 degree to 60 degrees, the waveform of the reference voltage signal continuously changes from a sine wave signal to a rectangular wave signal. That is, when Delta = 0 degrees, the signal is a sine wave signal, and when Delta = 60 degrees, the signal is a rectangular wave signal. As shown in FIG. 2, the three control modes are changed to change from a circular locus for low rotation and low torque to a hexagonal locus for high rotation and high torque. On the other hand, in the present embodiment, the reference voltage signal is a signal obtained by adding a sine wave signal and a rectangular wave signal, and the parameter of the angle Delta indicating the ratio of the addition is continuously changed, whereby the magnetic flux trajectory is circular. The trajectory can be changed continuously from the hexagonal trajectory. Therefore, according to the present embodiment, seamless control can be performed without switching the control mode. In the present embodiment, since it is not necessary to switch the control mode in this way, torque fluctuation associated with the control mode switching does not occur.

  Hereinafter, the configuration of the drive control apparatus of the present embodiment will be specifically described.

  FIG. 6 shows a configuration of a conventional PWM modulator. Reference voltage signals (output voltage command values) Van, Vbn, and Vcn for the phases a, b, and c are supplied to the PWM modulator 10. The PWM modulator 10 compares the supplied reference voltage signal with a predetermined triangular wave and outputs them as PWM modulation signals PWM1, PWM2, and PWM3, and on / off-controls the switching transistor of the inverter 3.

  On the other hand, FIG. 7 shows a configuration of the PWM modulator 12 in the present embodiment. The PWM modulator 12 includes a conventional PWM modulator 10 and a reference voltage signal calculator 11 provided in the preceding stage of the PWM modulator 10. Reference voltage signals (output voltage command values) Van, Vbn, and Vcn are supplied to the reference voltage signal calculator 11. The reference voltage signal calculator 11 generates new reference voltage signals VanNew, VbnNew, VcnNew from the reference voltage signals Van, Vbn, Vcn using the angle parameter Delta, and outputs them to the PWM modulator 10. The new reference voltage signal VanNew is a signal as shown in FIG. 5, and is a signal obtained by adding (or mixing) a sine wave signal and a rectangular wave signal using Delta.

FIG. 8 shows a flowchart of the calculation process in the reference voltage signal calculator 11 in FIG. Although the generation of the reference voltage signal for the a phase is shown, the same applies to the b phase and the c phase. First, for the input Van, Vbn, Vcn,
^{Vm = {Van 2 + (Vbn} -Vcn) 2/3} 1/2
Thus, the voltage value Vm is calculated (S101).

  Next, Vm · sin (π / 6−Delta / 2) is calculated using the angle parameter Delta, and this is compared in magnitude with the absolute value Abs (Van) of Van.

That is,
Abs (Van)> Vm · sin (π / 6-Delta / 2)
It is determined whether or not (S102).

If Abs (Van) is greater than Vm · sin (π / 6−Delta / 2), then the absolute value of Van is compared with Vm · sin (π / 6 + Delta / 2). That is,
Abs (Van) <Vm · sin (π / 6 + Delta / 2)
It is determined whether or not (S103).

If YES in S102 and YES in S103, that is,
Vm · sin (π / 6−Delta / 2) ≦ Abs (Van) ≦ Vm · sin (π / 6 + Delta / 2)
In this case, as a new reference voltage signal VanNew,
VanNew = Vm · sign (Van)
(S106). Here, sign (Van) is a function that is positive if the sign of Van is positive and negative if the sign of Van is negative. This corresponds to replacing this part of Van with a square wave.

On the other hand, if NO in S102 or NO in S103, the absolute value of Van and Vm · sin (π / 2−Delta / 2) are compared in magnitude. That is,
Abs (Van)> Vm · sin (π / 2−Delta / 2)
It is determined whether or not (S104).

In the case of YES in S104, similarly as a new reference voltage signal VanNew,
VanNew = Vm · sign (Van)
(S106). On the other hand, in the case of NO in S104, the current Van is directly used as a new VanNew (S105). This corresponds to leaving this part of Van as a sine wave.

As described above, a sine wave-like Van is generated and output as a new reference voltage signal VanNew in which a sine wave and a rectangular wave are combined. As can be seen from the processing of FIG. 8, whenever Delta is 0 degrees,
sin (π / 6−Delta / 2) = sin (π / 6 + Delta / 2)
= Sin (π / 6)
Since NO is determined in either S102 or S103, and NO is also determined in S104, Van is generated as VanNew as it is in S105. This means that the new reference voltage signal VanNew remains a sine wave.

If Delta is 60 degrees,
sin (π / 6-Delta / 2) = sin (0)
sin (π / 6 + Delta / 2) = sin (60)
And
sin (π / 2−Delta / 2) = sin (60)
Therefore, YES is determined in S103 or S104, and a rectangular wave is generated in S106. This means that the new reference voltage signal VanNew is a rectangular wave.

  The PWM modulator 12 of the present embodiment shown in FIG. 7 (hereinafter referred to as a “corrected PWM modulator” as appropriate) can be applied to various motor drive control devices. For example, the present invention can be applied to the scalar control motor drive device shown in FIG. 9 or the vector control motor drive device shown in FIG.

  In FIG. 9, the motor drive control device includes a scalar controller 20, a modified PWM modulator 12, an inverter 3, a basic component calculator 22, and a Delta calculator 24.

  The scalar controller 20 receives the target speed ωr *, and calculates and outputs reference voltage signals (output voltage command values) Van, Vbn, and Vcn based on the target speed ωr *. Since it is scalar control, there is no feedback component.

  The modified PWM modulator 12 is the PWM modulator 12 shown in FIG. 7, and generates and outputs new VanNew, VbnNew, and VcnNew from the input Van, Vbn, and Vcn. The modified PMW modulator 12 generates new reference voltage signals VanNew, VbnNew, and VcnNew based on the angle parameter Delta supplied from the Delta calculator 24.

  The basic component calculator 22 calculates a basic coefficient fc based on the target speed ωr * and the current motor speed ωc. The basic component calculator 22 includes a difference unit and a proportional integrator, calculates a difference between the target speed ωr * and the current speed ωc, and calculates a basic coefficient fc by proportionally integrating the error with the proportional integrator. .

The Delta calculator 24 calculates the angle parameter Delta based on the basic coefficient fc. In particular,
fc = 1 / π {8 sin (Delta / 2) + π-3Delta}
Delta is calculated using this relational expression. As the basic coefficient fc increases, Delta also increases accordingly. When the basic coefficient fc is 1, Delta is 0 degree.

  In FIG. 10, the motor control drive device includes a torque compensator 30, a magnetic flux calculator 32, a dq converter 34, a two-phase / three-phase converter 36, a modified PMW modulator 12, an inverter 3, and the like. , A basic component calculator 22, a Delta calculator 24, and an evaluator 42.

The torque compensator 30 corrects the target torque Te * based on the angle parameter Delta calculated by the Delta calculator 24. In particular,
Compensation torque = π / 3 · Te * {Delta-cos (Delta / 2) Ln {(1 + sin (Delta / 2)) / (1-sin (Delta / 2))}}
To correct the target torque Te *. In short, correction is performed so that the target torque Te * increases as Delta increases. The target torque Te * is obtained by proportionally integrating the error between the target speed ωr * and the current speed ωc by the PI unit.

  The magnetic flux calculator 32 calculates and outputs a target magnetic flux Ψ * corresponding to the motor speed ωc using a map prepared in advance.

  The dq converter 34 performs d-axis voltage command values Vd * and q by proportional integration using the difference between the target torque Te * and the current torque Te and the difference between the target magnetic flux Ψ * and the current magnetic flux Ψ. The shaft voltage command value Vq is calculated and output.

  The two-phase / three-phase converter 36 converts the d-phase and q-axis two phases into a-phase, b-phase, and c-phase, calculates Van, Vbn, and Vcn from Vd * and Vq * and outputs them. To do. The two-phase / three-phase converter 36 uses the phase angle ρs calculated by the evaluator 42 when converting the two-phase voltage signal into the three-phase voltage signal. The evaluator 42 calculates the phase angle ρs based on the motor rotor angle θr and the motor speed ωc.

  The basic component calculator 22 calculates a basic coefficient fc based on the difference between the target torque Te * and the current torque Te, and the target speed ωr * and the current motor speed ωc. The basic component calculator 22 includes a subtractor and a proportional integrator, and calculates a basic coefficient fc by proportionally integrating errors of these signals with the proportional integrator.

The Delta calculator 24 calculates the angle parameter Delta based on the basic coefficient fc. In particular,
fc = 1 / π {8 sin (Delta / 2) + π-3Delta}
Delta is calculated using this relational expression.

  The modified PWM modulator 12 is the PWM modulator 12 shown in FIG. 7, and generates and outputs new VanNew, VbnNew, and VcnNew from the input Van, Vbn, and Vcn. The modified PMW modulator 12 generates new reference voltage signals VanNew, VbnNew, and VcnNew based on the angle parameter Delta supplied from the Delta calculator 24.

  Thus, the modified PWM modulator 12 of this embodiment can be used for both scalar control and vector control.

  Below, the computer simulation result at the time of controlling the inverter 3 using the new reference voltage signal in this embodiment is shown.

  11 shows a new reference voltage signal generated by the modified PWM modulator 12. FIG. 11A shows the a-phase reference voltage signal VanNew, FIG. 11B shows the b-phase reference voltage signal VbnNew, and FIG. 11 (c) is a c-phase reference voltage signal VcnNew.

  FIG. 12 shows an a-phase reference voltage signal and a PWM modulation signal corresponding to the reference voltage signal. FIG. 12A shows the reference voltage signal VanNew, and FIG. 12B shows the PMW modulation signal.

  FIG. 13 shows a reference voltage signal (inter-line reference voltage signal) between the a phase and the b phase and a PWM modulation signal corresponding to the reference voltage signal. FIG. 13A shows the reference voltage signal VabNew, and FIG. Modulation signal.

  FIG. 14 collectively shows signals obtained by PWM-modulating reference voltage signals between the a phase and the b phase, between the b phase and the c phase, and between the c phase and the a phase, and FIG. 14A shows a VabNew modulated signal, FIG. 14B shows a VbcNew modulation signal, and FIG. 14C shows a VcaNew modulation signal.

  FIG. 15 shows VabNew, VbcNew, and VcaNew PWM modulation signals and magnetic flux trajectories when the angle parameter Delta = 0 degrees. FIG. 15A shows a VabNew PWM modulation signal, and FIG. 15B shows VbcNew. The PWM modulation signal, FIG. 15C shows the VcaNew PWM modulation signal, and FIG. 15D shows the magnetic flux locus at this time. When Delta = 0 degrees, the magnetic flux trajectory is circular on a two-dimensional plane of d-axis and q-axis.

  FIG. 16 shows VabNew, VbcNew, and VcaNew PWM modulation signals and magnetic flux trajectories when the angle parameter Delta = 30 degrees, FIG. 16A shows the VabNew PWM modulation signal, and FIG. 16B shows VbcNew. The PWM modulation signal, FIG. 16C shows the VcaNew PWM modulation signal, and FIG. 16D shows the magnetic flux locus at this time. When Delta = 30 degrees, the magnetic flux trajectory is a mixture of a circular trajectory and a linear trajectory.

  FIG. 17 shows VabNew, VbcNew, and VcaNew PWM modulation signals and magnetic flux trajectories when the angle parameter Delta = 60 degrees, FIG. 17A shows VabNew PWM modulation signals, and FIG. 17B shows VbcNew. The PWM modulation signal, FIG. 17C shows the VcaNew PWM modulation signal, and FIG. 17D shows the magnetic flux locus at this time. In the case of Delta = 60 degrees, the magnetic flux locus is a hexagon.

  As described above, Delta gradually increases from 0 degrees to 60 degrees as the basic coefficient fc increases. In relation to the motor speed, since the basic coefficient fc is small in the low speed range, the Delta is small accordingly, and the magnetic flux locus is circular as shown in FIG. As the motor speed increases, the basic coefficient fc also increases. Accordingly, Delta also increases sequentially, and the magnetic flux trajectory is not constant as shown in FIG. Further, in the high speed range where the motor speed is increased, the basic coefficient fc is further increased, and accordingly, Delta is also close to 60 degrees, and the magnetic flux locus is a hexagon as shown in FIG.

  As is clear from a comparison between FIG. 15 and FIG. 17, the average torque decreases when the magnetic flux locus changes to a hexagonal shape. For this reason, it is necessary to compensate the average torque which decreases according to Delta. This is why the torque compensator 30 is present. In the case of the scalar control shown in FIG. 9, the target speed ωr * may be similarly corrected according to Delta.

  As described above, a sine wave signal and a rectangular wave signal are added (or mixed or combined) using the angle parameter Delta as a reference voltage signal, and the inverter 3 is subjected to switching control with a signal obtained by PWM modulation of the added reference voltage signal. By doing so, the magnetic flux trajectory can be seamlessly changed from a circle to a hexagon. Therefore, it is possible to cope with the change in the angle parameter Delta continuously without switching the control mode from the low rotation low torque range to the high rotation high torque range of the vehicle. Can be prevented.

  Further, in the present embodiment, since the control of the plurality of modes is not switched as in the prior art, the motor 4 can be driven and controlled by a single control mode using the angle parameter Delta, so that the configuration becomes simpler.

  Further, the modified PWM modulator 12 of the present embodiment generates a new reference voltage signal from the supplied output voltage command value or reference voltage signal using the angle parameter Delta, and the supplied output voltage command value. Alternatively, it does not matter whether the reference voltage signal is generated by scalar control or vector control. That is, the modified PWM modulator 12 of the present embodiment has versatility applicable to both scalar control and vector control.

  1 battery, 2 step-up converter, 3 inverter, 4 motor, 10 PWM modulator, 11 reference voltage signal calculator, 12 modified PWM modulator, 24 Delta calculator.

Claims (4)

An AC motor drive control device,
Generating means for generating a reference voltage signal which is a control target;
Correction means for correcting and outputting the reference voltage signal from the generation means as a signal obtained by adding a sine wave signal and a rectangular wave signal according to the speed of the AC motor;
Modulation means for PWM-modulating the reference voltage signal corrected by the correction means and supplying it to the switching element of the inverter;
And a drive control apparatus for an AC motor, wherein the control is performed in a single control mode using the corrected reference voltage signal. The apparatus of claim 1.
Means for calculating an angle parameter Delta (where 0 ≦ Delta ≦ 60) whose value increases as the speed or torque of the AC motor increases in accordance with the speed or torque of the AC motor;
The correction means uses the angle parameter Delta to correct the reference voltage signal so that the delta region is a sine wave signal and the 60-Delta region is a rectangular wave region so that sine wave regions and rectangular wave regions appear alternately. An AC motor drive control device characterized by the above. The apparatus of claim 2.
The correcting means is
The three-phase reference voltage signals from the generating means are Van, Vbn, and Vcn, respectively.
Voltage ^{Vm = {Van 2 + (Vbn} -Vcn) 2/3} 1/2
Means for computing
The absolute values Abs of Van, Vbn, and Vcn are
Vm · sin (π / 6−Delta / 2) ≦ Abs ≦ Vm · sin (π / 6 + Delta / 2)
Means for replacing the sine wave signal with the rectangular wave signal having the voltage value Vm as an amplitude when satisfying,
Abs> Vm · sin (π / 2-Delta / 2)
Means for replacing the sine wave signal with the rectangular wave signal having the voltage value Vm as an amplitude when satisfying,
An AC motor drive control device comprising: The device according to any one of claims 1 to 3,
The AC motor drive control device, wherein the generation means generates the reference voltage signal by either scalar control or vector control.

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