Carrier-based Generalized Discontinuous PWM Strategy for Single-Phase Three-Legs Active Power Decoupling Converters

Three-legs active power decoupling (APD) converters are widely studied in the single-phase grid-connected systems to enhance the circuit lifetime by creating an alternative path for the typical existing dc-side power pulsating ripple. Therefore, this reduces the requirement of smoothing dc capacitors allowing compact designs even with the implementation of long life metalized film technology. In this article, to allow enhancement of the system power density by improving power conversion efficiency and thus reducing the requirement of thermal management of the semiconductors, a carrier-based generalized discontinuous PWM strategy is proposed. This method detects the converter ac currents and ac reference voltages to determine the optimum clamped duration in each one of the three bridge-legs, which will minimize the converter overall switching losses. The proposed modulation method is analyzed and validated on a PLECS simulation and a 2 kVA single-phase three-legs APD converter.