Performance analysis of a transformerless solar inverter with modified PWM

This paper aims to analyze the enhanced performance of grid connected transformerless inverters (GCTI) by the application of novel Wide Band Gap (WBG) devices with modified PWM. Highly Efficient Reliable Inverter Concept (HERIC) is chosen for this study because of its excellent common-mode noise cancellation capabilities and numerous solar photovoltaic applications. HERIC inverter works efficiently for linear loads with conventional pulse-width-modulation. However, non-linear loads introduce circulating freewheeling currents that distort the output current and hence deteriorate the power quality. Distortions in the output current will also increase the requirements to the output filter. Simulations based on spice models have been developed to perform a comprehensive analysis of the application of GaN switches in HERIC inverter for a modified PWM technique. The detailed results obtained demonstrate successful reduction in THD by 10% at a carrier frequency of 200 kHz, 400 V DC bus voltage and 230 V
_RMS
grid voltage.