A Suitable Single-phase PWM Current Source Inverter for Utility Interactive Photovoltaic Generation System

Abstract

A suitable single-phase inverter for the utility interactive photovoltaic generation system is proposed. The single-phase PWM current source inverter has a novel circuit configuration which is added a auxiliary branch to the normal single-phase bridge circuit. In order to reduce the size and weight of the dc reactor, a double frequency parallel resonance circut (LC tank circuit) is inserted in the dc side of the inverter. In result, the double frequency voltage appeared in the dc side of the inverter due to the pulsation of the single-phase instantaneous power is perfectly suppressed by the tank circuit. The constant dc current without pulsation is supplied from PV array to the inverter. The inverter provide a sinusoidal ac current for domestic loads and the utility line with unity power factor.
The virtual maximum power of the PV array can be obtained without any feedback control. In the system, the PV array can play an important role as a current-limitter by its V-I characteristics. Computed waveformes by simulation are shown. The excellent inverter equipment will be realized with smaller size and lighter weight than a conventional inverter.