An effective method for Electromagnetic Interference (EMI) reduction in single-phase full bridge inverters

The application of power electronic converters in renewable energy power generation systems like solar/wind power generation and electric vehicle applications is increasing rapidly. Electro Magnetic Interference (EMI) is a major concern in Power Electronic based Energy conversion systems. The EMI issues in the Pulse Width Modulated (PWM) inverter system arises from the high rate of change of voltage [dv/dt] and rate of change of switching current [di/dt], which are due to the fast switching of the power semiconductor devices. Flapping the important parameters of an inverter over a particular range can reduce the stress of the power semiconductor devices, and consequently the EMI noise. An effective EMI reduction technique called flapping technique to reduce the stress of the single phase full bridge inverter switches is presented in this paper. A relationship is developed among the various parameters involved in the flapping concept such as flapping frequency range for a given fundamental frequency (sweep), Bandwidth (Amplitude), Magnitude (Duty cycle), Phase of the flapping signal (Contrast). An analysis is carried out for different flapping ranges by varying the parameter values to minimize the EMI. The flapping technique is applied in the generation of PWM signal for single phase full bridge inverter and the results are analyzed for EMI reduction capability. The theoretical concepts have been simulated using MATLAB and significant reduction in EMI is noticed.