Motor control device

A motor control device which controls a driving of a motor using DC power that is output from a DC power supply, comprising:

• an inverter that converts a DC power into an AC power and supplies the AC power to the motor;
• a converter that has a plurality of switching elements, converts a DC voltage from the DC power supply into an input voltage which is a voltage to be input to the inverter, and supplies the input voltage to the inverter;
• and
• a control device that controls the plurality of switching elements such that the input voltage becomes a target input voltage which is a target value,
• wherein the control device has
• a rotation speed calculation unit that calculates a rotation speed of the motor;
• an optimum voltage calculation unit that calculates an optimum input voltage which is the input voltage at which the sum of power losses generated by each of the inverter, the motor, and the converter is a minimum, in a case in which the motor is operated at a motor operating point defined by the rotation speed calculated by the rotation speed calculation unit and a set target torque which is a target value of a torque that is generated by the motor;
• a minimum voltage calculation unit that calculates a minimum input voltage which is a minimum value of the input voltage required to operate the motor at the motor operating point;
• and
• a target value setting unit that sets either one of the optimum input voltage and the minimum input voltage as the target input voltage,
• wherein, in a case in which the set target torque exceeds a predetermined value, the target value setting unit sets the minimum input voltage lower than the optimum input voltage as the target input voltage,
• wherein, in a case in which the set target torque exceeds the predetermined value, the target value setting unit sets the minimum input voltage as the target input voltage, and
• wherein, in a case in which the set target torque is equal to or less than the predetermined value, the target value setting unit sets the higher of the optimum input voltage and the minimum input voltage as the target input voltage.