IMPROVEMENTS IN EMC PERFORMANCE OF INVERTER-FED MOTOR-DRIVES

An experimental investigation of conducted radio-noise emission from a conventional pulse width modulated (PWM) inverter of medium power fee ding an induction motor is described. It is determined that the invert er system generates considerable impulse currents through the power le ads feeding the system resulting in serious conducted electromagnetic interference (EMI) problems and significant voltage waveform distortio n in the power system. The dominant emission sources in the system are identified. A proposed model of the drive system for the purpose of e valuation of EMI are developed. Several low-cost strategies for improv ement in EMC performance of the PWM inverter are then proposed. Experi mental results demonstrate that disturbance from the modified system c an be dramatically reduced and that the EMC performance of the system has come very close to meeting the IEC CISPR and FCC limits on conduct ed emissions for digital devices [1], [2], [7].