JP2013110909A - Motor drive and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive and a control method for the same capable of generating a sinusoidal resolver excitation signal that synchronizes with a carrier triangular wave.SOLUTION: A motor drive includes an invertor 13 for supplying a PWM modulated motor current to a three-phase motor M1, and a current detection sensor for detecting a current flowing in the three-phase motor M1, for detecting a current angle of the three-phase motor M1 using a resolver 14. If the frequency of the carrier triangular wave used for PWM modulation is changed, the motor drive changes an excitation signal command value that generates the resolver excitation signal to be supplied to the resolver 14, and the frequency of the triangular wave for generating an excitation signal. Since the resolver excitation signals are generated using these excitation signal command values and the triangular waves for generating excitation signals, it becomes possible to make the valley of the carrier triangular wave to be synchronized with the peak of the resolver excitation signals, thereby achieving a precise current control as a result of minimized current ripple.

Description

  The present invention relates to a motor drive device that detects the current flowing through an AC motor and the electrical angle of the AC motor and controls the rotational drive of the AC motor, and a control method therefor.

  For example, an AC motor (hereinafter simply referred to as “motor”) is provided with a current sensor that detects current flowing in each phase of the motor. Further, a resolver for detecting an electrical angle (motor phase) is provided on the rotating shaft of the motor, and the driving of the motor is controlled based on the electrical angle detected by the resolver and each phase current of the motor. .

  Further, since the motor generates an alternating current using a current command value (sine wave) and a carrier triangular wave, EMI noise caused by the carrier triangular wave is generated. In other words, EMI noise having a peak at a frequency that is an integral multiple of the frequency of the carrier triangular wave is generated, and this EMI noise may interfere with the operation of the radio and various communication devices. In order to reduce this EMI noise, it has recently been proposed that the spectrum of the EMI noise is spread by changing the frequency of the carrier triangular wave so that the EMI noise does not concentrate on a certain frequency. .

  However, if the frequency of the carrier triangle wave is changed, the motor current detection timing determined by the carrier triangle wave cycle and the electrical angle detection timing determined by the resolver excitation signal cycle will not match, and this will cause current ripple. Occurs, the motor rotation is not smooth, or vibration is generated. In order to suppress this, it is necessary to synchronize the current detection of the motor and the electrical angle detection. In other words, it is necessary to change the period of the excitation signal command value (sine wave) supplied to the resolver in conjunction with the period fluctuation of the carrier triangular wave.

  Therefore, as described in, for example, Japanese Patent Application Laid-Open No. 2009-254040 (Patent Document 1), a rectangular wave having a duty ratio of 50% is shaped to generate a sine wave, and this sine wave is excited by a resolver. When used as a signal command value and the frequency of the carrier triangular wave changes, excitation is performed by changing the timing of the leading edge (rising edge) and trailing edge (falling edge) of the rectangular wave according to the change in frequency. It has been proposed to control the signal command value so as to be synchronized with the carrier triangular wave.

JP 2009-254040 A

  However, since the conventional example disclosed in Patent Document 1 described above employs a method of generating a sine wave-like resolver excitation signal by passing a rectangular wave having a duty ratio of 50% through a low-pass filter, for example, excitation of a resolver There is a problem that the method of generating the signal command value by PWM control cannot be applied.

  The present invention has been made to solve such a conventional problem, and the object of the present invention is to synchronize with a carrier triangular wave in a case where a method of generating an excitation signal command value by PWM control is adopted. It is an object of the present invention to provide a motor driving apparatus capable of generating a sine wave resolver excitation signal and a method for controlling the motor driving apparatus.

  In order to achieve the above object, the present invention detects the electrical angle of an AC motor using a switching means for supplying a PWM modulated motor current to an AC motor, a current detection means for detecting a current flowing in the AC motor, and a resolver. Electrical angle detection means for performing, and frequency changing means for changing the frequency of the carrier signal used for PWM modulation. The electrical angle detection means includes excitation signal generation means for generating a sinusoidal excitation signal supplied to the resolver, and resolver output signal detection means for detecting a peak from the output signal of the resolver. Then, the excitation signal generation means generates an excitation signal by PWM control using the excitation signal generation PWM pulse, the period of the excitation signal changes in proportion to the period of the carrier signal, and the electrical angle detection means The electrical angle of the AC motor is detected in synchronization with the carrier signal.

  In the motor drive device and the motor control device according to the present invention, even when the period of the carrier triangular wave is changed for the purpose of reducing EMI noise, the electrical angle is detected by PWM control in accordance with the change in the period. Since the detection period of the electrical angle in the resolver can be changed, the accuracy of detecting the electrical angle can be improved.

It is a block diagram which shows the structure of the motor drive device which concerns on one Embodiment of this invention. It is a circuit diagram which shows the detailed structure of the inverter mounted in the motor drive device which concerns on one Embodiment of this invention. 6 is a timing chart showing a carrier triangular wave, a current command value, and an on / off operation of each semiconductor switch used in the motor drive device according to the embodiment of the present invention. It is a circuit diagram which shows the detailed structure of the resolver mounted in the motor drive device which concerns on one Embodiment of this invention. It is a characteristic view which shows the change of the excitation voltage of the resolver mounted in the motor drive device which concerns on one Embodiment of this invention, the voltage detected by a 1st detection coil, and the voltage detected by a 2nd detection coil. It is a block diagram which shows the circuit structure of the resolver mounted in the motor drive device which concerns on one Embodiment of this invention, and the electrical angle detection means which controls this. It is explanatory drawing which shows the waveform of an excitation signal command value when the period of the carrier triangular wave used for the motor drive device concerning one embodiment of the present invention is constant, and when the period changes. It is explanatory drawing which shows the change of the triangular wave for excitation signal generation, and the PWM pulse for excitation signal generation when the period of the carrier triangular wave used for the motor drive device concerning one embodiment of the present invention changes. It is explanatory drawing which shows the change of the triangular wave for excitation signal generation, and the PWM pulse for excitation signal generation when the period of the carrier triangular wave used for the motor drive device concerning the modification of the present invention changes. It is explanatory drawing which shows the relationship between the carrier triangular wave and excitation signal command value which concern on the other modification of this invention.

[Description of Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a motor control device according to an embodiment of the present invention. As shown in FIG. 1, the motor control device 100 generates a current command value based on a desired speed command value and an actual speed value calculated from an electrical angle detection value of the three-phase motor M1 (AC motor). A controller 11, a current controller 12 that outputs a PWM control signal based on the current command value generated by the speed controller 11, the current detection value of the three-phase motor M1, and the motor electrical angle detection value; and the current An inverter (switching means) 13 that generates a three-phase AC voltage from a DC voltage based on a PWM control signal output from the controller 12 and an electrical angle of the three-phase motor M1 connected to the rotating shaft of the three-phase motor M1 And a resolver 14 for detection.

  FIG. 2 is a circuit diagram showing a detailed configuration of the inverter 13. As shown in FIG. 2, the inverter 13 includes six semiconductor switches Vup, Vun, Vvp, Vvn, Vwp, and Vwn. Each of these semiconductor switches is constituted by a MOSFET, for example. Each semiconductor switch Vup, Vun, Vvp, Vvn, Vwp, Vwn is turned on / off by a PWM control signal output from the control device 21 (corresponding to the speed controller 11 and current controller 12 shown in FIG. 1). The DC voltage output from the DC power supply VB is converted into a three-phase AC voltage, and the converted three-phase AC voltage is output to the U-phase, V-phase, and W-phase of the three-phase motor M1. In addition, the control apparatus 21 can be comprised with the microcomputer provided with central processing unit (CPU), RAM, ROM etc., for example.

  FIG. 3 is a characteristic diagram showing processing for generating ON / OFF signals of the semiconductor switches Vup, Vun, Vvp, Vvn, Vwp, and Vwn based on the current command value supplied to the current controller 12 and the carrier triangular wave. . As shown in FIG. 3, in the current controller 12, each semiconductor switch is turned on from the magnitude relationship between the carrier triangular wave that fluctuates at a constant period and the current command values Iu, Iv, Iw of the U phase, V phase, and W phase. An off signal is generated. In practice, dead times are provided between Vup and Vun, between Vvp and Vvn, and between Vwp and Vwn, but this is omitted in FIG.

  Further, each phase current of the three-phase motor M1 can be detected by providing a shunt resistor (not shown) for current detection at the sources of the N-side semiconductor switches Vun, Vvn, and Vwn shown in FIG. In addition, since the sum of each phase electric current becomes zero, it is good also as only two shunt resistors. The detected current is fed back to the current controller 12. At this time, the current is detected when the N-side semiconductor switch is open, that is, when the carrier triangular wave is a trough. Here, the inverter 13 includes a function as current detection means for detecting a current flowing through the three-phase motor M1.

  In addition, since the current controller 12 generates the PWM control signal using the current detection value and the motor electrical angle detection value, it is necessary to match the current detection timing with the motor electrical angle detection timing. Furthermore, in the present embodiment, the current controller 12 executes control for reducing EMI noise by changing the period of the carrier triangular wave. That is, the current controller 12 has a function as frequency changing means for changing the period (frequency) of the carrier signal (carrier triangular wave) used for PWM modulation.

  Since the current controller 12 changes the period of the carrier triangular wave as will be described later, the current detection timing (the timing at which the carrier triangular wave becomes a valley) changes with this period change. Therefore, in order to cope with this change, in the present embodiment, the detection timing of the motor electrical angle is changed by a method described later.

  Next, the resolver 14 shown in FIG. 1 will be described in detail with reference to FIGS. FIG. 4 is a configuration diagram of the resolver 14, and FIG. 5 is an explanatory diagram illustrating waveforms of an input signal and an output signal of the resolver 14. As shown in FIG. 4, the resolver 14 includes an exciting coil L0 provided in a rotor (rotor) of the three-phase motor M1, a power supply unit 33 that applies a sinusoidal voltage VEx to the rotor, and a three-phase motor. A first detection coil L1 and a second detection coil L2 are provided at positions where the phases of the stator (stator) of M1 are different from each other by 90 degrees. In addition, voltmeters V1 and V2 (detection voltages are also indicated by the same symbols V1 and V2) are connected to the first and second detection coils L1 and L2, respectively.

  Then, when a sinusoidal voltage VEx is applied from the power supply unit 33 to the excitation coil L0, a voltage is induced in the first detection coil L1 and the second detection coil L2. Here, the voltages induced in the first detection coil L1 and the second detection coil L2 are the sine wave and the cosine wave respectively applied to the excitation coil L0 as the rotor rotates. The signal is amplitude-modulated. That is, when a sinusoidal voltage VEx as shown in FIG. 5A is applied to the excitation coil L0, a voltage V1 having a waveform as shown in FIG. 5B is induced in the first detection coil L1. A voltage V2 having a waveform as shown in FIG. 5C is induced in the second detection coil L2.

  If the voltage applied to the excitation coil L0 is sin (ωt), the voltage V1 detected by the first detection coil L1 is sin (ωt) × Asinθ, and the voltage V2 detected by the second detection coil L2 is sin (ωt). ) × Acos θ. Where θ is the electrical angle of the three-phase motor, and A is a constant. Based on the voltage signals detected by the first and second detection coils L1 and L2, the electrical angle θ of the three-phase motor can be obtained by the following equation (1).

θ = tan ⁻¹ {(sin (ωt) × Asinθ) / (sin (ωt) × Acosθ)}
= Tan ⁻¹ (sin θ / cos θ) (1)
Here, the voltage signal actually detected by the first and second detection coils L1 and L2 includes a sine wave component of the excitation signal. Therefore, in order to detect the electrical angle θ of the three-phase motor, it is necessary to detect the amplitude of the envelope waveform of each output signal. For this purpose, the electrical angle is measured at the timing when each output V1, V2 peaks. It is desirable to detect. That is, in order to obtain the electrical angle θ with high accuracy, it is desirable to detect the output signal at the peak timing of each output signal, and it is desirable to obtain the electrical angle θ in synchronization with the carrier triangular wave.

  FIG. 6 is a block diagram showing the electrical configuration of the resolver 14 and the electrical angle detection means for supplying the excitation signal to the resolver 14 and measuring the electrical angle θ of the three-phase motor M1. As shown in FIG. 6, the electrical angle detection means includes a CPU 31 that performs overall control and an amplifier 32, and is connected to the excitation coil L0 and the first and second detection coils L1 and L2 of the resolver 14. ing.

  The CPU 31 includes an output terminal T1, and two A / D input terminals T2 and T3. The output terminal T1 is connected to the amplifier 32, the output terminal is connected to the exciting coil L0, and the input terminal T2 is connected to the input terminal T2. It is connected. The first and second detection coils L1, L2 are connected to the input terminals T3, T4.

  The CPU 31 generates a PWM pulse signal from the magnitude relationship based on the excitation signal generating triangular wave and the excitation signal command value by a method described later, and outputs the PWM pulse signal from the output terminal T1. That is, the CPU 31 has a function as an excitation signal generating unit that generates an excitation signal (sine wave) to be supplied to the resolver 14.

  The PWM pulse signal is amplified by the amplifier 32 and then applied to the exciting coil L0 of the resolver 14. Thereby, a sinusoidal voltage is applied to the exciting coil L0. That is, the sine wave voltage shown in FIG. 5A is applied to the exciting coil L0. In addition, voltage signals detected by the first detection coil L1 and the second detection coil L2 are supplied to the input terminals T3 and T4.

  The resolver 14 calculates the electrical angle θ of the three-phase motor M1 based on the voltage signal detected by the first and second detection coils L1 and L2, using the above-described equation (1). θ is output to the speed controller 11 and the current controller 12 shown in FIG. That is, the CPU 31 has a function as a resolver output signal detection unit that detects a peak from the output signal of the resolver 14.

  As described above, when the period of the carrier triangular wave is changed, the CPU 31 changes the period of the excitation signal command value (sine wave) along with the change of the period, and further, the excitation signal generating triangular wave. Change the period of the sine wave generation triangle wave that becomes the excitation signal. At this time, as shown in FIG. 8, the period of the carrier triangular wave and the period of the excitation signal command value are made to coincide with each other, and further, an integer number of excitation signal generating triangular waves are set for one period of the carrier triangular wave. In the case of FIG. 8 described later, the number of excitation signal generating triangular waves is set to ten.

  Next, processing for changing the period of the voltage applied to the exciting coil L0 of the resolver 14 in conjunction with the period change when the period of the carrier triangular wave is changed will be described with reference to FIGS. . First, the case where the period of the carrier triangular wave does not change will be described. As shown in FIG. 7A, the excitation signal command value S2 (voltage applied to the excitation coil L0) has a period of the carrier triangular wave S1. And the peak of the excitation signal command value and the trough of the carrier triangular wave coincide with each other. Therefore, the electrical angle θ of the three-phase motor M1 can be detected at the same timing as the current control cycle of the three-phase motor M1, and current ripple can be suppressed.

  On the other hand, when the cycle of the carrier triangular wave varies, it is necessary to change the excitation signal command value so that the cycle of the carrier triangular wave S3 matches the cycle of the excitation signal command value S4 as shown in FIG. There is. Hereinafter, processing for changing the period of the excitation signal command value will be described with reference to the waveform diagram shown in FIG.

  As shown in FIG. 8, when the period of the carrier triangular wave changes from t1 to t2, the period of the excitation signal command value is changed according to the ratio of this change, and further, the period of the excitation signal generating triangular wave is changed. Let For example, when the period of the carrier triangular wave is 1.5 times, the period of the excitation signal command value is 1.5 times, and the period of the excitation signal generating triangular wave is also 1.5 times. Then, by using the excitation signal generating triangular wave whose period has been changed and the excitation signal command value, it is possible to generate a resolver excitation signal that varies in synchronization with the period of the carrier triangular wave.

  In this case, the number of excitation signal generating triangular waves existing in one carrier triangular wave period is the same regardless of the fluctuation of the carrier triangular wave period (the number of exciting signal generating triangular waves is 10 for both t1 and t2. If the number of triangular waves for generating the excitation signal is counted, the next electrical angle detection timing can be detected.

  Next, the operation of the motor control device according to this embodiment will be described. When the drive control of the three-phase motor M1 shown in FIG. 1 is started, the speed controller 11 calculates a current command value and outputs it to the current controller 12, and further, the current controller 12 A PWM signal for driving the motor M1 is generated and output.

  The inverter 13 controls the semiconductor switches Vup, Vun, Vvp, Vvn, Vwp, and Vwn (see FIG. 2) on and off based on the PWM signal to generate a three-phase AC voltage to generate the three-phase motor M1. AC voltage is output to each phase of U phase, V phase, and W phase. Thereby, the three-phase motor M1 is rotationally driven. Further, the inverter 13 detects the current flowing through the three-phase motor M1, and the data of the current detection value is fed back to the current controller 12. The rotation angle of the three-phase motor M1 is detected by the resolver 14, and the detected value is fed back to the speed controller 11 and the current controller 12 as an electrical angle θ.

  Here, as described above, in this embodiment, the current controller 12 performs control to change the period of the carrier triangular wave used when generating the PWM signal in order to reduce the level of a desired band of EMI noise. . That is, as shown in FIG. 8 as an example, control is performed to change the period of the carrier triangular wave from t1 to t2.

  A control signal indicating that the period of the carrier triangular wave has been changed is output to the CPU 31 of the resolver 14 shown in FIG. 6, and the CPU 31 generates a resolver excitation signal in accordance with a change in the period of the carrier triangular wave. The command value to be used, that is, the excitation signal command value is changed. Specifically, as shown in FIG. 7 described above, the excitation signal command value is set so as to coincide with the cycle of the carrier triangular wave. At the same time, the period of the excitation signal generating triangular wave is also changed. For example, as shown in FIG. 8, when the period of the carrier triangular wave is changed to 1.5 times, the period of the excitation signal command value is set to 1.5 times, and the excitation signal generating triangular wave is linked with this. Is changed to 1.5 times.

  Then, a PWM signal (excitation signal generation PWM signal) is generated based on the excitation signal generation triangular wave and the excitation signal command value, and the generated PWM signal is output to the excitation coil L0 shown in FIG. As a result, an excitation signal (resolver excitation signal) having the same cycle as the carrier triangular wave is supplied to the excitation coil L0, and the measurement period of the electrical angle detected by the voltmeters V1 and V2 is the carrier triangular wave. It will be in agreement with the period.

  Therefore, even when the period of the carrier triangular wave is changed as a measure against EMI noise, the detection period of the electrical angle θ changes with the change of the period, and the timing for detecting the current and the timing for detecting the electrical angle. Therefore, it is possible to control the motor with high accuracy.

  In the above-described embodiment, an example in which the period of the carrier triangular wave and the period of the resolver excitation signal are matched has been described. However, the period of the resolver excitation signal may be matched with a plurality of periods of the carrier triangular wave.

  Thus, in the motor drive device and the control method thereof according to the present embodiment, the PWM signal is generated using the excitation signal generating triangular wave and the excitation signal command value, and the resolver excitation signal is generated using the PWM signal. When the electrical angle θ of the three-phase motor M1 is measured, control is performed so that the excitation signal command value is changed in accordance with the change in the carrier triangular wave period even when the carrier triangular wave period is changed. . That is, the period of the carrier triangular wave is changed so that the period of the excitation signal command value coincides. Further, the period of the excitation signal generating triangular wave is changed.

  Then, a PWM signal is generated using the changed excitation signal command value and the excitation signal generating triangular wave, and a resolver excitation signal is generated by the PWM. Therefore, since the electrical angle θ of the three-phase motor M1 can be measured according to the period of the carrier triangular wave, the current ripple generated due to the deviation of the electrical angle detection timing during the current control can be suppressed, and the high accuracy. Motor control is possible.

  Moreover, the current command value calculation in the current control can be performed with the current value and the electrical angle θ detected at the same time, and the current ripple generated due to the timing deviation can be suppressed.

  Furthermore, since the period of the excitation signal generating triangular wave is changed in accordance with the period of the carrier triangular wave, it is possible to generate an excitation signal generating PWM pulse corresponding to the period fluctuation of the carrier triangular wave.

  Further, as shown in periods t1 and t2 in FIG. 8, even if the period of the carrier triangular wave changes, the number of excitation signal generating triangular waves for one period of the carrier triangular wave is constant (example in FIG. 8). Then, t1 and t2 are both 10), and once the peak timing of the excitation signal generated in the resolver 14 is detected, the peak timing can be obtained by counting the number of PWM signals thereafter. For this reason, it is not necessary to detect the peak of the resolver excitation signal every cycle, the calculation load of the microcomputer can be reduced, and highly accurate motor electrical angle detection can be realized.

  In this case, it is necessary to correct the excitation signal command values (the sine wave with the period t1 and the sine wave with the period t2 shown in FIG. 8) for generating the PWM pulse in accordance with the period of the PWM pulse. That is, the fact that the periods of the PWM pulses are different means that the height (amplitude) of the excitation signal generating triangular wave used for generating the PWM pulse is different, and therefore the PWM pulses having the same duty ratio are used. When generating, it is necessary to correct the command value of the excitation signal sine wave according to the height of the excitation signal generating triangular wave.

[Description of modification]
Next, a modification of this embodiment will be described. In the above-described embodiment, when the period of the carrier triangular wave is changed as shown in FIG. 8, the period of the excitation signal generating triangular wave is changed accordingly, and the excitation signal generating triangular wave for one period of the carrier triangular wave is changed. Although the number is the same, in this modification, as shown in FIG. 9, when the period of the carrier triangular wave is changed, the number of excitation signal generating triangular waves is changed, and the excitation signal generating triangular wave is changed. The period is the same.

  That is, as shown in FIG. 9, when the period of the carrier triangular wave changes from t3 to t4, control is performed so that the number of excitation signal generating triangular waves increases by the amount of the changed period. Specifically, when the period of the carrier triangular wave is t3, the number of excitation signal generating triangular waves is 10, and when the period of the carrier triangular wave is t4, the number of exciting signal generating triangular waves is 15. The

  At this time, it is set so that an integer of the period of the carrier triangular wave becomes the period of the excitation signal generating triangular wave. In the example shown in FIG. 9, when the period of the carrier triangular wave is changed from t3 to t4, each of the periods t3 and t4 is set to be an integral multiple of the period of the excitation signal generating triangular wave.

  Then, a PWM pulse is generated using the exciting signal generating triangular wave, and the PWM pulse is applied to the exciting coil L0 shown in FIG. 4 to measure the electrical angle θ synchronized with the period of the carrier triangular wave. It becomes possible.

  By doing so, it is necessary to correct the excitation signal command value accompanying the period change of the carrier triangular wave (period change of the PWM pulse) (that is, when changing from the period t1 to t2, as shown in FIG. 8) Therefore, it is possible to suppress an increase in calculation load by the CPU 31 shown in FIG. The restriction that the period of the carrier triangular wave is an integral multiple of the period of the excitation signal generating triangular wave is described above. The higher the clock frequency of the CPU 31, the greater the degree of freedom of the carrier triangular wave period. It becomes easy and it becomes possible to reduce said restrictions.

[Description of other modifications]
Next, another modification of the present embodiment will be described. In the above-described embodiment, as shown in FIG. 7B, the example in which the cycle of the carrier triangular wave S3 and the excitation signal command value S4 coincide is described. That is, the time from the valley of the carrier triangular wave to the valley is matched with the time from the peak to the peak of the excitation signal command value, and the timing at which the carrier triangular wave becomes the valley and the timing at which the excitation signal command value peaks. Thus, an example in which the timings of the motor current detection and the electrical angle detection are matched is shown.

  On the other hand, in another modified example, as shown in FIG. 10, each period of the carrier triangular wave (time from valley to valley) and each period of excitation signal command value (time from peak to peak) However, the timing of the valley of the carrier triangular wave (motor current detection timing) and the peak timing of the excitation signal command value (motor electrical angle detection timing) are shifted by a certain time Δt.

  When current control is performed by the microcomputer (current controller 12 shown in FIG. 2), if there are restrictions on the number of input ports and analog / digital converters, motor current detection and motor electrical angle Since detection may not be performed at the same time, the same effect as that of the above-described embodiment can be achieved by shifting the detection timings of both by a fixed time Δt.

  In other words, if the time Δt of deviation between the carrier triangular wave valley timing and the excitation signal command value peak timing is known in advance, the current control can be performed by calculation based on this time Δt. Ripple generated in the current can be suppressed, and high-precision motor control is possible.

  The motor control device and the motor control method of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to this, and the configuration of each unit is an arbitrary configuration having the same function. Can be replaced.

  For example, in the present embodiment, an example in which a MOSFET is used as a switching element provided in the inverter 13 has been described. However, the present invention is not limited to this, and other semiconductor switches such as IGBTs can also be used. .

  The present invention can be used to measure the electrical angle with high accuracy even when the period of the carrier triangular wave is changed.

DESCRIPTION OF SYMBOLS 11 Speed controller 12 Current controller 13 Inverter 14 Resolver 21 Control apparatus 31 CPU
32 Amplifier 33 Power supply unit 100 Motor control device L0 Excitation coil L1 First detection coil L2 Second detection coil M1 Three-phase motor Vup, Vun, Vvp, Vvn, Vwp, Vwn Semiconductor switch V1, V2 Voltmeter VB DC power supply

Claims (6)

Switching means for supplying PWM-modulated motor current to the AC motor;
Current detecting means for detecting a current flowing in the AC motor;
Electrical angle detection means for detecting the electrical angle of the AC motor using a resolver;
Frequency changing means for changing the frequency of the carrier signal used for the PWM modulation;
With
The electrical angle detection means includes excitation signal generation means for generating a sinusoidal excitation signal supplied to the resolver, and resolver output signal detection means for detecting a peak from the output signal of the resolver,
The excitation signal generation means generates the excitation signal by PWM control using an excitation signal generation PWM pulse, and the period of the excitation signal changes in proportion to the period of the carrier signal,
Further, the electric angle detection means detects an electric angle of the AC motor in synchronization with the carrier signal.   The electrical angle detection unit controls the timing at which the electrical angle detection unit detects the electrical angle and the timing at which the current detection unit detects the motor current to coincide with each other or have a certain amount of deviation. The motor driving device according to claim 1. The excitation signal generation means generates the excitation signal generation PWM pulse based on the excitation signal command value and the excitation signal generation triangular wave,
3. The motor driving device according to claim 1, wherein a cycle of the excitation signal generating triangular wave is changed in accordance with a cycle of the carrier signal and a cycle of the excitation signal. 4.   4. The motor driving apparatus according to claim 3, wherein the excitation signal generating means sets the number of excitation signal generating triangular waves to be constant during one excitation signal cycle.   The excitation signal generating means sets the period of the excitation signal generating triangular wave to be constant and sets the period of the excitation signal generating triangular wave to be an integral number of the period of the carrier signal. The motor drive device according to claim 1 or 2. A current supply step of supplying PWM-modulated motor current to the AC motor;
A current detection step of detecting a current flowing through the AC motor;
An electrical angle detection step of detecting an electrical angle of the AC motor using a resolver;
A frequency changing step of changing the frequency of the carrier signal used for the PWM modulation,
The electrical angle detection step includes an excitation signal generation step for generating a sinusoidal excitation signal supplied to the resolver, and a resolver output signal detection step for detecting a peak from the output signal of the resolver,
The excitation signal generation step generates the excitation signal by PWM control using an excitation signal generation PWM pulse, and the period of the excitation signal changes in proportion to the period of the carrier signal,
Furthermore, the electrical angle detection step detects the electrical angle of the AC motor in synchronization with the carrier signal.

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