A Novel Active Interphase Transformer Scheme to Achieve Three-Phase Line Current Balance for 24-Pulse Converter

A new active interphase transformer (IPT) scheme to achieve three-phase line current balance for a 24-pulse converter is proposed in this paper. The proposed active IPT scheme consists of three IPT and a current-controlled inverter with required rating only 1.16% of system power rating. A current injection method for an active IPT is also proposed in this paper. The balance of three-phase current and high power quality can be achieved by injecting compensation current into the secondary winding of the active IPT. Moreover, the proposed scheme can operate in flexible load configurations, by which separated loads can be connected to the separated outputs of the converter independently. The operation criteria for flexible load arrangements are analyzed to obtain better performance. System simulation is conducted and a 6-kW laboratory prototype is built both for evaluation and test. Both simulation and experimental results demonstrate the validity of the proposed scheme.