US Patent 11791758 Inverter device and motor device comprising same

An inverter device is provided. The inverter device converts power from a power source and drives a motor. The inverter device includes an inverter circuit having a switch, a driver circuit that switches the switch on and off, and a controller that controls the driver circuit. The controller has a speed calculator used to calculate a minimum speed of the motor based on a power source voltage. After the controller performs fail-safe control, when a speed of the motor is less than the minimum speed, the fail-safe control is ended.