Modeling and Analysis for Simulation of Common-Mode Noises Produced by an Inverter-Driven Air Conditioner

This paper presents an intensive discussion on conducted electromagnetic interference (EMI) emissions from an inverter-driven air conditioner. Common-mode voltages produced by the pulsewidth-modulated (PWM) inverter may cause a high-frequency leakage current. The use of a spectrum analyzer and a line-impedance stabilization network (LISN) makes it possible to refer the leakage current in the time domain to the conducted-EMI emission levels in the frequency domain, which are prescribed by the EMI regulations. Simulation-based estimation of the conducted-EMI emission levels in advance allows engineers to efficiently design a cost-effective EMI filter intended for meeting the regulations. This paper achieves modeling of the inverter-driven air conditioner with focus on common-mode voltages and leakage-current propagation paths. The simulation circuit developed can be used to predict conducted-EMI emission levels and to design the cost-effective EMI filter. Simulated results agree fairly with experimental ones in both cases of the EMI filter being connected and disconnected.