Drive system for rotating electric machine

A drive system for a rotating electric machine that functions as a running drive source for a vehicle, comprising:

• a collision detection unit that detects a collision or a possibility of collision of the vehicle;
• an inverter that converts direct current power supplied from a direct current supply into alternating current power and outputs the alternating current power to the rotating electric machine;
• a smoothing capacitor that smoothes a voltage between terminals of the inverter;
• and
• a controller that performs a discharge control for controlling the inverter, wherein
• when the collision or possibility of collision is detected, the controller cuts off a power output from the direct current supply, performs a revolution speed reduction control for reducing a revolution speed of the rotating electric machine to a value equal to or less than a predetermined first threshold, and then discharges electric charges accumulated in the smoothing capacitor, and wherein
• the controller performs a first control for switching on a switching element of one arm among an upper arm and a lower arm of the inverter for only one phase and switching off all other switching elements when the revolution speed of the rotating electric machine exceeds a second threshold that is higher than the first threshold in the revolution speed reduction control.