Modified DC-bus voltage balancing algorithm based three-level neutral point clamped (NPC) IPMSM drive for electric vehicle application

A modified DC-link voltage balancing scheme for a three-level neutral point clamped inverter (NPC) with an interior permanent magnet machine (IPMSM) is presented. It uses two DC-link voltage sensors to take care of the voltage differences, and keep it to a required tolerance level. Switching control strategy is developed using a space-vector pulse width modulation (SV-PWM) scheme. Number of switching per switching cycle is optimised to five and changes in control strategy, depending on two capacitor voltage differences are only allowed to take place at starting of each switching cycle. It helps to reduce the switching losses. Details simulation studies are carried out in Matlab/ Simulink platform and an experimental setup is developed using dspace® based real time emulator. Simulation and experimental results show effectiveness of the proposed system.