Electric motor control device and electric motor control method

An electric motor control method comprising:

• executing a current control mode in which a current command value to an electric motor is generated based on at least a torque command value by referring to a table prepared in advance, and a voltage applied to the electric motor is controlled to match the current command value;
• executing a voltage phase control mode in which a torque estimation value of the electric motor is calculated based on a torque computation formula based on a motor constant obtained by using a temperature as a parameter, and a feedback operation is performed for a voltage phase based on a difference between the torque estimation value and the torque command value;
• and
• switching to the voltage phase control mode in a high rotation area where a flux weakening control is performed,
• wherein in generation of the current command value, the current command value under the same temperature environment as a temperature parameter of the motor constant used when the torque estimation value is calculated is generated.

An electric motor control device comprising:

• a motor constant generation means for generating a motor constant by using a temperature as a parameter;
• a current control means, that has an electric current generation means for generating a current command value to an electric motor based on at least a torque command value by referring to a table prepared in advance, for executing a current control mode in which a voltage applied to the electric motor is controlled to match the current command value;
• a torque calculation means for calculating a torque estimation value of the electric motor based on a torque computation formula using the motor constant;
• a voltage phase control means for executing a voltage phase control mode in which a feedback operation is performed for a voltage phase based on a difference between the torque estimation value and the torque command value;
• and
• a control mode switching means for switching to the voltage phase control mode in a high rotation area where a flux weakening control is performed,
• wherein the electric current generation means generates the current command value under the same temperature environment as the temperature parameter of the motor constant used when the torque calculation means calculates the torque estimation value.