Operation of multi-phase converters with coupled inductors at reduced numbers of phases

In this paper multi-phase converters with coupled inductors are analyzed when operated with reduced number of phases. An n-phase magnetic equivalent circuit model is used to show the influence of the total output current on the additional leakage inductance caused by the reduced number of phases. The analysis shows that the output current ripple is significantly reduced at light load conditions leading to reduced power losses in the converter. A converter operation with reduced number of phases can be realized and hence a fault tolerant system with coupled inductors can be achieved. FEM simulations are used to visualize the flux density in the core and to verify the theoretical predictions. A full size prototype converter with coupled inductors has been built and tested to show the converter operation with reduced number of phases. Measurements confirm the theoretical predictions very well.