Drive and control apparatus for multiple-winding motor
A drive control apparatus for multiple-winding motor includes: a modulation rate phase command generation unit which calculates currents of first and second inverters for driving a multiple-winding three-phase motor and generates a modulation rate command and a phase command for equalizing the currents; a pulse number determination unit which determines the number of pulses per half cycle on the basis of a frequency command; a pattern table for storing switching patterns; and gate signal generators which control the first and second inverters, using an optimal switching pattern based on the number of pulses, wherein the modulation rate phase command generation unit performs control for equalizing currents of the first and second inverters, and the phase or frequency at which the control is performed is changed in accordance with any of the number of pulses, the modulation rate, the frequency command, and the switching pattern.
1. A drive control apparatus for multiple-winding motor, comprising:
a plurality of power converters each of which has a switching device for driving a multiple-winding AC motor and converts a DC power supply to a variable-voltage and variable-frequency AC power supply; and
a control unit for controlling the power converters, wherein
the control unit includes:
an output voltage control unit for calculating and outputting output voltage and an output voltage phase for driving the multiple-winding AC motor at a desired rotation speed; and
a PWM control unit for performing PWM control for the switching device,
the output voltage control unit includes:
an output voltage determination unit for determining the output voltage on the basis of a frequency command;
an output voltage phase calculating unit for calculating the output voltage phase through integration on the basis of the frequency command; and
a modulation rate phase command generation unit which calculates d-axis current and q-axis current of each power converter on the basis of the output voltage phase, calculates a modulation rate correction amount and a phase correction amount for each power converter in order to equalize currents flowing through windings of the multiple-winding AC motor, on the basis of the d-axis current and the q-axis current, and generates a modulation rate command and a phase command for controlling each power converter, on the basis of the modulation rate correction amount and the phase correction amount,
the PWM control unit includes:
a modulation rate calculation unit for calculating a modulation rate on the basis of the output voltage calculated by the output voltage control unit and DC voltage of the DC power supply;
a pulse number determination unit for determining a number of pulses per half cycle of the PWM control for the switching device, on the basis of the frequency command;
a pattern table for storing, for each number of pulses and for each magnitude of the modulation rate, a switching pattern for reducing a low-order harmonic in the output voltage; and
a gate signal generator for generating a gate signal for driving the switching device, using the switching pattern from the pattern table, on the basis of the modulation rate from the modulation rate calculation unit, the number of pulses from the pulse number determination unit, and the output voltage phase calculated by the output voltage control unit, and
the modulation rate phase command generation unit performs control for equalizing currents of the power converters, and a phase or frequency at which the control is performed is changed in accordance with any of the number of pulses, the modulation rate, the frequency command, and the switching pattern.
2. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit calculates a difference between the d-axis currents of the power converters and a difference between the q-axis currents of the power converters, and controls the differences to be zero.
3. The drive control apparatus for multiple-winding motor according to claim 2 , wherein
the modulation rate phase command generation unit sets a response of calculation of the modulation rate correction amount and the phase correction amount, to be lower than an output frequency calculated from the frequency command.
4. The drive control apparatus for multiple-winding motor according to claim 2 , wherein
the modulation rate phase command generation unit sets a predetermined limit value for calculated values of the phase correction amounts for the power converters, and changes the limit value in accordance with any of the number of pulses, the modulation rate, and the frequency command.
5. The drive control apparatus for multiple-winding motor according to claim 2 , wherein
the modulation rate phase command generation unit changes a number of significant decimal digits of calculation of the phase correction amounts for the power converters, or a bit length of the phase correction amounts, in accordance with any of the number of pulses, the modulation rate, and the frequency command.
6. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit
sets current reference values for d-axis and q-axis currents, using the d-axis and q-axis currents of the power converters,
calculates differences between the respective d-axis and q-axis currents of each power converter and the respective current reference values for d-axis and q-axis currents, and
controls the differences to be zero.
7. The drive control apparatus for multiple-winding motor according to claim 6 , wherein
the modulation rate phase command generation unit sets a response of calculation of the modulation rate correction amount and the phase correction amount, to be lower than an output frequency calculated from the frequency command.
8. The drive control apparatus for multiple-winding motor according to claim 6 , wherein
the modulation rate phase command generation unit sets a predetermined limit value for calculated values of the phase correction amounts for the power converters, and changes the limit value in accordance with any of the number of pulses, the modulation rate, and the frequency command.
9. The drive control apparatus for multiple-winding motor according to claim 6 , wherein
the modulation rate phase command generation unit changes a number of significant decimal digits of calculation of the phase correction amounts for the power converters, or a bit length of the phase correction amounts, in accordance with any of the number of pulses, the modulation rate, and the frequency command.
10. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit
sets specific one of the power converters as a reference power converter,
calculates differences between the respective d-axis and q-axis currents of the reference power converter and the respective d-axis and q-axis currents of each of the other power converters, and
controls the differences to be zero.
11. The drive control apparatus for multiple-winding motor according to claim 10 , wherein
the modulation rate phase command generation unit sets a response of calculation of the modulation rate correction amount and the phase correction amount, to be lower than an output frequency calculated from the frequency command.
12. The drive control apparatus for multiple-winding motor according to claim 10 , wherein
the modulation rate phase command generation unit sets a predetermined limit value for calculated values of the phase correction amounts for the power converters, and changes the limit value in accordance with any of the number of pulses, the modulation rate, and the frequency command.
13. The drive control apparatus for multiple-winding motor according to claim 10 , wherein
the modulation rate phase command generation unit changes a number of significant decimal digits of calculation of the phase correction amounts for the power converters, or a bit length of the phase correction amounts, in accordance with any of the number of pulses, the modulation rate, and the frequency command.
14. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit
sets current reference values for d-axis and q-axis currents, using the d-axis and q-axis currents of the power converters, and sets specific one of the power converters as a reference power converter,
for the reference power converter, calculates differences between the respective d-axis and q-axis currents of the reference power converter and the respective current reference values for d-axis and q-axis currents, and controls the differences to be zero, and
for the power converters other than the reference power converter, calculates differences between the respective d-axis and q-axis currents of each of the power converters and the respective d-axis and q-axis currents of the reference power converter, and controls the differences to be zero.
15. The drive control apparatus for multiple-winding motor according to claim 14 , wherein
the modulation rate phase command generation unit sets a response of calculation of the modulation rate correction amount and the phase correction amount, to be lower than an output frequency calculated from the frequency command.
16. The drive control apparatus for multiple-winding motor according to claim 14 , wherein
the modulation rate phase command generation unit sets a predetermined limit value for calculated values of the phase correction amounts for the power converters, and changes the limit value in accordance with any of the number of pulses, the modulation rate, and the frequency command.
17. The drive control apparatus for multiple-winding motor according to claim 14 , wherein
the modulation rate phase command generation unit changes a number of significant decimal digits of calculation of the phase correction amounts for the power converters, or a bit length of the phase correction amounts, in accordance with any of the number of pulses, the modulation rate, and the frequency command.
18. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit sets a response of calculation of the modulation rate correction amount and the phase correction amount, to be lower than an output frequency calculated from the frequency command.
19. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit sets a predetermined limit value for calculated values of the phase correction amounts for the power converters, and changes the limit value in accordance with any of the number of pulses, the modulation rate, and the frequency command.
20. The drive control apparatus for multiple-winding motor according to claim 1 , wherein
the modulation rate phase command generation unit changes a number of significant decimal digits of calculation of the phase correction amounts for the power converters, or a bit length of the phase correction amounts, in accordance with any of the number of pulses, the modulation rate, and the frequency command.