BigPatents India

An excitation circuit (10) for a flux switching motor (14). The circuit includes a low-value film capacitor across the DC side of a bridge rectifier. A plurality of electronic switches are arranged in an H-bridge configuration for switching current flow through an armature winding of the motor in accordance with a PWM control scheme and single-pulse control scheme controlled by microcontroller (18). A start-up diode is placed across the field winding of the motor and is electronically switched out of the circuit after a startup phase of the motor has completed. The circuit implements armature energy recirculation through the field winding during startup to promote more uniform and quicker startup of the motor. The use of a film capacitor improves the power factor of the circuit, helps to eliminate the introduction of harmonics into the AC voltage source, and helps in mitigating EMI. Reverse commutation is used to bring the motor to a quick stop when it is powered off.