Study on design of an active EMI filter for integrated power electronics modules

By a comparative study of active power filter and active EMI filter, the possibility of using active filter technique in the integrated power electronics modules (IPEM) has been analyzed in detail. An active EMI filter for IPEM is proposed in this paper, which consists of a wide bandwidth current transformer, liner amplifier circuit and high frequency current feed-in network. The relationship between the compensation performance and the gain is investigated, based on its two-port T network model. And the steady state characteristic curve is obtained. Considering the wide bandwidth feature of the EMI noise, the high frequency simplified model of the current transformer is established. The effective method to improve its bandwidth is well discussed. Simulation analysis and experiment results showed that, the developed active EMI filter gives satisfactory performance in noise compensation characteristics.