On discussion of motor drive conducted EMI issues

Precise conducted noise modeling of the drive and the effective EMI filter design based on the model will have directly impact on the overall optimal drive design. Both tasks are full of challenges. It is beneficial to review the status of EMI modeling and filter design of variable-speed AC drive systems thoroughly. Two basic approaches have been used to characterize and model conducted EMI emissions in an IGBT PWM inverter: time-domain EMI emission modeling and frequency-domain EMI emission modeling; High initial and operating cost of active EMI filter still prevents its widespread application in motor drive systems. Especially in small and medium raring drive products, passive conducted EMI filter still dominates. The survey results on effects of noise source impedance, component parasitic, and noise mode definitions on the filter design are presented.