Control device

A control device that generates a drive signal for controlling an inverter driving a motor, the control device comprising:

• a current value conversion unit that converts current flowing through the motor into a γ-axis current value and a δ-axis current value;
• a γ-δ current command value output unit that outputs a γ-axis current command value and a δ-axis current command value;
• a γ-δ voltage command value calculation unit that calculates a γ-axis voltage command value based on the γ-axis current value and the γ-axis current command value and calculates a δ-axis voltage command value based on the δ-axis current value and the δ-axis current command value;
• a drive signal conversion unit that converts the γ-axis voltage command value and the δ-axis voltage command value into the drive signal;
• an estimation unit that calculates an estimated position that is an estimated value of a position of the motor;
• and
• a first determination unit that determines whether or not position estimation of the motor is possible by the estimation unit, wherein
• an upper arm short circuit drive signal or a lower arm short circuit drive signal is generated when the motor is started or when the first determination unit determines that the position estimation of the motor is not possible, the upper arm short circuit drive signal being the drive signal for simultaneously turning on three-phase upper arm switching elements of the inverter and simultaneously turning off three-phase lower arm switching elements of the inverter, the lower arm short circuit drive signal being the drive signal for simultaneously turning off the three-phase upper arm switching elements of the inverter and simultaneously turning on the three-phase lower arm switching elements of the inverter, and
• when the upper arm short circuit drive signal or the lower arm short circuit drive signal is generated, the estimation unit calculates an estimated extended electromotive force, which is an estimated value of an extended electromotive force generated in the motor, from the γ-axis current value and the δ-axis current value, and calculates the estimated position that is the estimated value of the position of the motor based on the estimated extended electromotive force.