Output Voltage Regulation Curves for a 1-Switch Boost Converter Using Coupled Inductor Windings and Split DC-Rails Under Unbalanced Load Conditions

A 1-switch split dc-rail boost converter topology is described that uses a mutually coupled two winding inductor to balance the voltage drop across both of its capacitor smoothed input and output voltage terminals. The resultant converter obtains balanced input and output voltages under extreme unbalanced load conditions using no extra converter control features. A current sharing action between the two coupled windings is described, during both the on-time and off-time of the switch, and shown to be responsible for the voltage balancing feature. Simulations and experimental results are used to illustrate the nature of the winding current waveforms that produce this current sharing action. Load imbalances exceeding 2:1 can easily be compensated. Simulations and experimental results show that deviations of the converter input and output voltages, largely determined by the winding leakage inductance and the dc voltage gain, can be limited to within the range 1% to 8% for load imbalances of up to 2:1.