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. The common-mode voltages produced by the pulse-width-modulation (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 emissions in the frequency domain, which are prescribed by the EMI regulations. Estimating the conducted-EMI emissions by means of computer simulation in advance is beneficial for engineers who try to efficiently design a cost-effective EMI-filter intended for meeting the regulations. This paper achieves modeling of common-mode voltages, leakage-current propagation paths, and an EMI-filter for an inverter-driven air conditioner. The simulation circuit based on the developed models makes it possible to predict conducted-EMI emissions. Simulated results agree well with experimental ones in both cases of the EMI-filter being connected and disconnected.