Comparison of traditional two-stage buck-boost voltage source inverter and diode-assisted buck-boost voltage source inverter

This paper investigates the wide range voltage modulation, low cost, high efficiency and high power density DC/AC power conversion in renewable energy applications. Three different DC/AC converters: conventional dc-dc boosted voltage source inverter, diode-assisted buck-boost voltage source inverter and diode-assisted buck-boost voltage source inverter with constant dc-link voltage using typical pulse width modulation strategies were compared to discuss their advantages and disadvantages in various practical applications. Voltage stress, current stress and power rating of total switching devices, passive components requirement of each of these system configurations are derived and calculated. Then, design examples of fuel cell power drive system with different system configurations are conducted and compared from aspects of design cost, efficiencies, power density under the same input and output conditions. Calculation and simulation results show that diode-assisted buck-boost voltage source inverter demonstrates advantages in design cost and good performance in power conversion when voltage gain is high (larger than 2.5).