Input current shaping in brushless DC motor drives utilizing inverter current control

It is proposed that the PWM inverter of a conventional brushless DC motor drive be treated as a buck converter. In particular, if the DC link capacitor is simply eliminated then a basic buck configuration current shaper can be realized. In this configuration the inverter switches can be used to control the motor current as before but can also be used indirectly to shape the average input current wave shape. In effect the control strategy hinges on the fact that the power to the rectifier pulsates unidirectionally at twice line frequency if the input current is sinusoidal and the power factor is unity