Common-mode electromagnetic interference calculation method for a PV inverter with chaotic SPWM

With the emergence of renewable energy power generation, varied kinds of DC-AC inverters based on SPWM control including photovoltaic (PV) inverters have been widely applied in practice. However, high-frequency operations of switches under traditional SPWM (TSPWM) will lead to obvious EMI peaks on switching frequency and its multiples, which may cause serious electromagnetic interference (EMI) problem. As a new kind of spread spectrum technology, Chaotic SPWM (CSPWM) is proposed in recent years and got widely researched in the worldwide. CSPWM has strong effectiveness on EMI suppressing and only need simple realization means. At present stage, there are some researches analyzed the EMI of PV inverters under CSPWM by spectrum calculation approach, however, these researches only focus on output voltage and output current of the PV inverters, which lack of the EMI analysis method based on the EMI conducted paths. This paper put forward a spectrum calculation method for the common mode EMI (CM-EMI) current under C SPWM. This method is designed based on CM-EMI paths and double Fourier series. In addition, simulation and experiment tests are given on a single phase PV inverter. Comparisons between the calculation results and the test results would be done to verify the correctness of the CM-EMI spectrum calculation method for CSPWM.