Compensation of discontinuous conduction in single phase grid connected PWM inverters

Nowadays the increasing utilization of renewable energy sources demand power converters capable of delivering high quality energy to the low voltage grid. The traditional dead-time compensation methods handle high-power operating conditions well, but low-power conditions and discontinuous conduction require further investigation. This paper identifies four cases of discontinuous conduction in single phase half bridge inverters, and describes the resulting nonlinearities. Based on these results and on the three cases of continuous conduction, an improved dead time compensation method is shown for single phase PWM inverters. The compensator chooses the actual one from the seven cases, and calculates the corresponding error voltage. The result is used for correction at duty cycle level. The capabilities of the compensator are shown via simulation on a system without a PI current controller, so the results can be easily compared with other existing methods.