Drive control device for motor

A drive control device for a motor, the drive control device serving to control drive of the motor, the drive control device comprising:

• an input terminal that receives a direct current voltage;
• an output terminal that outputs an alternating current voltage to the motor;
• an inverter circuit that converts the direct current voltage into the alternating current voltage, and outputs the alternating current voltage to the output terminal;
• a first switch unit that shorts the output terminal based on a control signal;
• a capacitor that is connected to the input terminal, and is charged with the direct current voltage;
• a diode that is connected between the input terminal and the capacitor, and limits a direction where a charge current for charging the capacitor flows;
• a rectifier circuit that rectifies an induced voltage generated in the motor, and outputs a rectified voltage;
• a photo coupler that converts the rectified voltage into an optical signal, and thereafter, converts the optical signal into a converted signal;
• a second switch unit that outputs the control signal based on the converted signal, the second switch unit including a second switch unit input terminal connected to the capacitor and a second switch unit output terminal that outputs the control signal;
• and
• a voltage detector that detects whether the direct current voltage is input to the input terminal, and determines whether to negate the control signal,
• wherein
• the second switch unit
• outputs a voltage of the second switch unit input terminal as the control signal to the second switch unit output terminal when not receiving the converted signal, and
• does not output the control signal to the second switch unit output terminal when receiving the converted signal, and
• the voltage detector negates the control signal when detecting that the direct current voltage is input to the input terminal.