Transformer based resonant DC link inverter for brushless DC motor 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 pulse-width modulation inverter, which is normally relative low efficiency since the switching power losses across the switching devices are high. In order to reduce the losses, a lot of 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 soft-switching inverter based on transformer which can generate dc link voltage notches during chopping switches commutation to guarantee all switches working in zero voltage switching condition. The operation principle and control scheme of the inverter are analyzed. Simulation and experimental results are proposed to verify the theoretical analysis.