Revolution rate regulated motor without motor current limiting, especially burner motor for vehicle heater, is monitored for free-running/resistance, and switched off if resistance excessive

摘要

The motor has a controller for regulating the motor speed and for a fault-initiated cut-off. The motor is monitored for free-running or running resistance and is switched off if a defined degree of resistance to free running is detected. The electric motor is only switched off after a time delay. Resistance is derived from the change in revolution rate when the motor is temporarily switched off for a short period (deltaT).