Electric machine control method and electric machine control device

An electric machine control device comprising:

• a current command generation unit configured to generate a current command value based on a torque command value to an electric machine;
• a current vector control unit configured to calculate a first voltage command value so that an output current of the electric machine follows the current command value;
• a voltage amplitude generation unit configured to calculate a voltage norm command value based on a power-supply voltage and a predetermined modulation rate command value;
• a voltage phase generation unit configured to calculate a voltage phase based on the power-supply voltage and the torque command value;
• a voltage phase control unit configured to calculate a second voltage command value based on the voltage norm command value and the voltage phase;
• a control mode determination unit configured to select either one of the first voltage command value and the second voltage command value in accordance with a predetermined condition;
• a voltage command value switching unit configured to set, as a voltage command value, the selected one of the first voltage command value and the second voltage command value;
• a modulation rate calculation unit configured to calculate a modulation rate based on the power-supply voltage and the voltage command value;
• a compensation gain calculation unit configured to calculate a compensation gain used to linearize a relationship between a magnitude of the voltage command value and a magnitude of a fundamental wave component of an output voltage to the electric machine in accordance with the modulation rate;
• a compensated voltage command value calculation unit configured to calculate a compensated voltage command value based on the voltage command value and the compensation gain;
• an output control unit configured to control the output voltage to the electric machine based on the compensated voltage command value;
• and
• a compensation gain limiting unit configured to limit the compensation gain to be equal to or less than a predetermined upper limit.