Generation and suppression of conducted EMI from inverter-fed motor drives

This paper focuses on a systematic analysis of the conducted electromagnetic interference (EMI) from an inverter-fed motor drive system. It proposes a theory to explain how the conducted EMI is generated. The theory states that the EMI can be produced from the system by two different mechanisms: parasitic capacitive coupling and inductive load current switching. Each of the EMI mechanisms is discussed in detail. Suppression methods are also suggested to help effectively reduce the EMI emission. Validation of the theory and suppression methods are then performed experimentally based on a brushless PM motor drive.