Improved interleaved discontinuous carrier-based PWM strategy for 3-level coupled inductor inverters

An improved interleaved discontinuous Pulse Width Modulation (PWM) technique is presented for multilevel coupled inductor inverters (CII). The CII performance is dependent to the inductor current ripple and associated coupled inductor losses. A new approach is developed based on interchangeable overlapping switching states in the CII topology. The proposed method maximizes the use of switching states with a high-effective inductance and minimizes the inductor current ripple by inverting the interleaved carrier waveforms for the upper and lower switches in one of the inverter switching phases. The proposed method has a superior performance compared to traditional carrier-based methods by minimizing the inductor losses and, thus, improving the inverter performance. The new method is also superior over the space vector techniques due to its easy implementation and simple algorithm. The inverter performance is validated through simulation analysis and experimental results.