Motor drive device

A motor drive device comprising:

• an inverter circuit having switching elements provided correspondingly to a plurality of phases of a motor having a multi-phase motor coil, and a smoothing capacitor provided in parallel with the switching elements;
• a drive circuit portion that drives the switching elements by outputting an operation signal to the inverter circuit;
• a control portion that controls the drive circuit portion by pulse width modulation (PWM) to make the switching elements to conduct switching operation;
• and
• an operating voltage generation portion that supplies power to the drive circuit portion and the control portion by generating an operating voltage for the drive circuit portion and the control portion, wherein:
• the inverter circuit converts a DC voltage from a first power supply to an AC voltage by PWM control by switching the switching elements and outputs the AC voltage to the multi-phase motor coil;
• the control portion outputs a PWM signal to the drive circuit portion according to a drive state command value of the motor output from a high-level control device that operates on power from a second power supply outputting a voltage lower than the first power supply;
• the operating voltage generation portion is capable of generating the operating voltage using power fed from either of the first power supply and the second power supply;
• and
• when the motor is stopped, the control portion performs a discharge control operation to discharge charges from the smoothing capacitor.

A motor drive device comprising:

• an inverter circuit having switching elements provided correspondingly to a plurality of phases of a motor having a multi-phase motor coil, and a smoothing capacitor provided in parallel with the switching elements;
• a drive circuit portion that drives the switching elements by outputting an operation signal to the inverter circuit;
• a control portion that controls the drive circuit portion by pulse width modulation (PWM) to make the switching elements to conduct switching operation;
• and
• an operating voltage generation portion that supplies power to the drive circuit portion and the control portion by generating an operating voltage for the drive circuit portion and the control portion, wherein:
• the inverter circuit converts a DC voltage from a first power supply to an AC voltage by PWM control by switching the switching elements and outputs the AC voltage to the multi-phase motor coil;
• the control portion outputs a PWM signal to the drive circuit portion according to a drive state command value of the motor output from a high-level control device that operates on power from a second power supply outputting a voltage lower than the first power supply;
• the operating voltage generation portion is capable of generating the operating voltage using power fed from either of the first power supply and the second power supply;
• and
• a load driven by the motor is a compression mechanism which draws in and compresses a refrigerant in a refrigeration cycle installed to a vehicle.