Pole-number-changing rotary electric machine and driving method for pole-number-changing rotary electric machine

A driving method for a pole-number-changing rotary electric machine including a rotary electric machine provided with a stator in which stator slots are arranged at regular intervals in a mechanical angle direction and a rotor rotated by magnetomotive forces generated by a current flowing through stator coils housed in the stator slots, the driving method comprising:

• supplying, by an n-group inverter, an m-phase current to the stator coils;
• and
• controlling, by circuitry, the n-group inverter,
• each of the magnetomotive forces corresponding to the stator slots being arranged at regular intervals, and a number of poles in the pole-number-changing rotary electric machine being changed between a first number of poles and a second number of poles, wherein the second number of poles is smaller than the first number of poles;
• and
• performing, by the circuitry, current supply in which an m-phase current is supplied to the stator coils by the n-group inverter, and in the current supply:
• at the time of a polarity driving corresponding to the second number, current phases of the current flowing through the stator coils are controlled such that a current phase degree of freedom, which is a number of current phases used in stator slots that correspond to one pole pair controllable by the n-group inverter, is equal to a number of groups n×a number of phases m, where the number of groups n is 4 or a multiple of 4 and the number of phases m is 3 or a natural number greater than 3 and m and n are prime numbers relative to each other, and
• at the time of a polarity driving corresponding to the first number, the current phases of the current flowing into the stator coils are changed such that the current phase degree of freedom is equal to the number of groups n×the number of phases m/2.

A pole-number-changing rotary electric machine comprising:

• a rotary electric machine provided with a stator in which stator slots are arranged at regular intervals in a mechanical angle direction and a rotor rotated by magnetomotive forces generated by a current flowing through stator coils housed in the stator slots;
• an n-group inverter configured to supply an m-phase current to the stator coils;
• and
• circuitry configured to control the n-group inverter,
• each of the magnetomotive forces corresponding to the stator slots being arranged at regular intervals, and a number of poles in the pole-number-changing rotary electric machine being changed between a first number of poles and a second number of poles, wherein the second number of poles is smaller than the first number of poles, wherein
• the circuitry controls current phases of the current flowing through the stator coils such that a current phase degree of freedom, which is a number of current phases used in stator slots that correspond to one pole pair controllable by the n-group inverter, is equal to a number of groups n×a number of phases m/2 at a time of a polarity driving corresponding to the first number and is equal to a number of groups n×the number of phases m at a time of a polarity driving corresponding to the second number, where the number of groups n is 4 or a multiple of 4 and the number of phases m is 3 or a natural number greater than 3 and m and n are prime numbers relative to each other.