An Efficient Resonant Pole Inverter With One Single Auxiliary Switch of Each Phase for AC Motor Drive

This brief presents an efficient resonant pole inverter for the sake of the efficiency improvement of the inverter. Its design process is elaborated briefly as follows: the same auxiliary units are added in parallel with three bridge arms and auxiliary units on each bridge arm only consist of one auxiliary switch, two auxiliary diodes, two resonant capacitors and two coupled resonant inductors; when the auxiliary units work, the voltage across main switches can decrease to zero periodically before main switches are switched on. Thus, main switches can acquire zero-voltage switching, making for the reduction of switching loss. In particular, the notable advantage of the presented inverter is that only one switch is included in the auxiliary units of each phase, which is beneficial to the simplification of the control strategy and the restriction on the hardware cost. Moreover, the single auxiliary switch of each phase can also acquire zero-current switching. This brief illustrates each working state in a switching period. The relative experimental waveform indicates that switching devices attain soft-switching. Furthermore, the efficiency of the presented inverter achieves 98% at rated output power, increasing by 0.3%, compared with that in the latest literature. Consequently, the presented inverter is more advantageous in efficiency than other similar soft-switching inverters.