A PWM Coordination Strategy to Reduce DC-Link Capacitor Dependence in Converter-Inverter Systems

The usually bulky, heavy and expensive DC-link capacitors create barrier to increasing power density and reliability of energy conversion system in electric-powered vehicles. This paper proposes an online PWM coordination strategy to reduce the ripple current stress of the DC-link capacitors between the cascaded converter and inverter stages. The efficacy of the proposed strategy is substantiated by analysis, simulation and experiment, and also by comparison with other alternative capacitor minimization methods. Practical issues in implementation such as dead-time compensation are also discussed.