Abstract：The topology of H-bridge hybrid cascaded with voltage ratio 1∶2 can achieve seven-level output to improve power density. With the modulation of multi-carrier stacked, the switches of one bridge in the low voltage unit are working at high frequency, and the switches of the other bridge are working at low frequency. The uneven heat distribution will shorten the life of the device and endanger the system. Therefore, this paper presents a modified modulation. By maintaining the same output characteristics and efficiency, the max switch working frequency of each unit can be reduced by half, and all the switches of each unit can work at the same state. The modified modulation is helpful to increase the life of the switches and the stability of the system.
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2016, Vol. 31 
