Main loop equivalent circuit of H-bridge power unit for EMI analysis

In order to construct high frequency equivalent circuit of main loop in large capacity converter, an H-bridge unit, which is widely used in large capacity inverter, was studied. The equivalent circuit of the busbar was established based on partial element equivalent circuit (PEEC) method. The parasitic parameters of the DC link capacitor tank were identified by least square curve fitting on transition process. Transient bridge voltage as excitation to the equivalent circuit, the simulation response current is very close to the measured current during the reverse recovery process. The result demonstrates that the accuracy of the equivalent circuit is reasonable and the modeling method is feasible and effective.