Novel Soft Switching Inverter for Brushless DC Motor using Fuzzy Logic

Brushless DC motor (BLDCM) has been broadly used in drive systems and servo control because of its fast response, high power density, high efficiency, low inertia, high reliability and maintenance free. It is however driven by a hard-switching PWM inverter, which has low switching frequency, high switching loss, high electro-magnetic interference (EMI), high acoustic noise and low efficiency, etc. To solve these problems of the hard switching inverter, many soft switching inverters have been designed in the past. Unfortunately, high device voltage stress, large dc link voltage ripples, complex control scheme and so on are noticed in the soft switching inverters. This paper introduces a novel fuzzy logic based soft-switching inverter using transformer, which can generate dc link voltage notches during chopping which minimize the drawbacks of soft switching. Hence all switches work in zero voltage switching condition. The operation principle and control scheme of the inverter are analyzed and performance of the fuzzy controller is compared with conventional PI controller. The simulation results show that the fuzzy controller renders a better transient response than the PI controller resulting in negligible overshoot and smaller settling time. Simulation results are proposed to verify the theoretical analysis.