Discussion of internal and external high frequency common mode noise current on a chopper circuit

The mechanism of common-mode noise current in control and gate-drive circuits on a chopper circuit is discussed. For high power density configurations, common-mode noise current flows not only in the main circuit, but also in the control and gate-drive circuits. This noise current increases the risk of control circuit misoperation, and might flow out from control and gate-drive circuits and interfere in a utility line, etc. The factors for the generation of noise currents and the propagation paths of these noise currents are examined. The influence of this noise current on the EMI noise is shown from the experimental results.