Novel soft-switching inverter for brushless DC motor variable speed drive system

Brushless DC motor has been widely used in industrial applications because of its low inertia, fast response, high power density, high reliability and maintenance-free. It is usually supplied by a hard-switching PWM inverter, which normally has low efficiency since the power losses across the switching devices are high. In order to reduce the losses, many soft switching inverters have been designed. Unfortunately, there are many drawbacks, such as high device voltage stress, large DC link voltage ripple, complex control scheme and so on. This paper introduces a novel soft-switching inverter which generates notches of the DC bus voltage becomes to zero during chopping switches commutation to guarantee all switches working in zero voltage state. The result of this investigation will be very useful for industrial applications.