Analysis of interference of electromagnetic noise in an electric compressor for vehicle air-conditioning systems with an integrated mechanical and electrical structure

Since a motor drive system contains an inverter (high-voltage circuit) and gate drive circuits (low-voltage circit) with a switching regulator, electromagnetic noise is generated in each of these two circuits, and noise interference between these circuits can occur. This paper discusses noise interference between the high- and low-voltage circuits of an electric compressor system with an integrated mechanical and electrical structure. Analysis using LTspice shows that the experimental and analytical results are in good agreement when a very small stray capacitance occurs between the high- and low-voltage circuits. An experiment using an actual compressor showed that conducted noise above 20 MHz can be reduced by up to 10 dB by reducing the effect of stray capacitance between these circuits.