Elimination of Filter Inductor in Switching Cell AC-AC Converters Using Magnetic Integration

The switching cell (SC) direct pulse width modulation ac-ac converters have several advantages; in particular, they do not experience commutation issues, are not susceptible to reverse-recovery losses of body diode of switching devices, produce output waveforms of good quality, are more immune to EMI noise, and have smaller input/output current ripples. The magnetic components of the SC ac-ac converters consist of coupled inductors and a filter inductor. This paper proposes an integrated inductor which integrates all magnetic components of the SC ac-ac converters into one magnetic assembly. The leakage inductance of the proposed integrated inductor is utilized to eliminate the filter inductor in buck, boost, and buck - boost-type SC ac-ac converters. The proposed integrated inductor improves the power density and reduces cost and losses because it requires fewer magnetic cores, coils, and soldering connections. The proposed integrated inductor is especially suitable for high-current applications because it can avoid the magnetic core saturation caused by current, and can eliminate the air gap in the core. The proposed integrated inductor can realize high leakage inductance; therefore, the input and output current ripples can be reduced significantly. To verify the proposed integrated inductor, a 2.3-kW prototype inductor was built and tested.