Electric machine controlling method and electric machine controlling device

An electric machine controlling device for executing either one of a current vector control and a voltage phase control such that supply power to an electric machine is controlled in accordance with an operating state of the electric machine, the electric machine controlling device comprising:

• an inverter configured to supply alternating-current power to the electric machine based on a voltage command value of the electric machine;
• a sensor configured to detect a current supplied from the inverter to the electric machine;
• and
• a controller configured to calculate a voltage command value for the voltage phase control based on a voltage norm command value indicative of a magnitude of a supply voltage to the electric machine and a voltage phase command value indicative of a phase of the supply voltage, wherein
• the controller calculates a state amount of either one of magnetic flux generated in the electric machine or a parameter correlated to the magnetic flux, based on the current detected by the sensor;
• and
• the controller changes the voltage norm command value in accordance with the state amount.