Controller for rotary electric machine drive apparatus

A controller for a rotary electric machine drive apparatus that is provided with a converter which can raise a power source voltage of a direct current power source to output to a system voltage line, and an inverter which is provided between the converter and a rotary electric machine and performs power conversion between direct current power of the system voltage line and alternating current power which drives the rotary electric machine, the controller for the rotary electric machine drive apparatus comprising:

• a converter controller that controls the converter so that a system voltage which is a direct current voltage of the system voltage line approaches a voltage command value, in the case where the voltage command value is larger than the power source voltage;
• and
• a voltage command calculator which calculates the voltage command value within a range which is larger than or equal to the power source voltage and is smaller than or equal to an output upper limit voltage of the converter;
• wherein the voltage command calculator is provided with
• a required minimum voltage calculator that calculates a required minimum voltage which is a minimum system voltage required in the case of performing a maximum torque/current control of the rotary electric machine under conditions of the present torque command value and the present rotational speed of the rotary electric machine;
• and
• a loss minimum command calculator that, in the case where the required minimum voltage is larger than or equal to the power source voltage and is smaller than or equal to the output upper limit voltage of the converter, calculates a converter loss coefficient which is a coefficient of a polynomial in which the system voltage is a variable and represents a power loss characteristic of the converter;
• calculates an inverter loss coefficient which is a coefficient of a polynomial in which the system voltage is a variable and represents a power loss characteristic of the inverter;
• calculates a sum total of the converter loss coefficient and the inverter loss coefficient for each order of the polynomials;
• based on the calculated sum total loss coefficient for each order, calculates a low loss voltage which is the system voltage from which a sum total power loss of the converter and the inverter becomes a minimum, within a candidate voltage range which is larger than or equal to the required minimum voltage and is smaller than or equal to the output upper limit voltage of the converter;
• and sets the low loss voltage as the voltage command value.