A soft switching three-level pulse-width modulation (PWM) converter is presented for industrial electronics with wide voltage range operation, such as solar power or fuel cell applications. Phase shift PWM scheme is used on the input-side to accomplish the zero voltage turn-on on power switches and improve the converter efficiency. Three-level diode-clamp circuit topology is adopted in the presented circuit to lessen the voltage ratings on active devices for high voltage applications. Three sub-circuits with the different turns-ratio of transformers can be selected in the presented converter in order to achieve 10:1 (V in,max = 10V in,min ) wide input voltage operation when compared to the conventional multilevel converter. The proposed circuit is a single-stage converter instead of two-stage converter to realize wide voltage operation. Therefore, the presented converter has less component counts. Finally, the design procedure and experiments with a 300W laboratory circuit are presented and discussed to confirm the circuit analysis and converter performance.Electronics 2020, 9, 47 2 of 20 ZVS converters [24][25][26][27][28] can further eliminate the switching losses for medium voltage applications. However, the wide voltage operation is seldom discussed and investigated in conventional three-level soft switching converters. The input voltage range of the three-level converter that is discussed in [20][21][22][23][24][25][26][27][28] is less than 4:1 voltage range operation. For some wind power or solar power applications, the input voltage of DC converters might be greater than 6:1 or 8:1 voltage range, i.e., V in,max ≥ 6 or 8 V in,min .A ZVS three-level DC/DC converter is discussed and then investigated to have 10:1 (80 V~800 V) wide input voltage operation and ZVS operation on active devices. The presented three-level converter has three winding turns and three auxiliary switches on the output-side to achieve wide voltage range operation. Three auxiliary switches on the secondary-side are active or inactive and three different turns-ratio of the isolated transformer are connected to the output load based on the input voltage value. Thus, three equivalent sub-circuits can be operated in the proposed converter to achieve wide voltage operation. Three-level neutral-point diode-clamp converter is adopted on the input-side to have the advantages of low voltage rating and soft switching operation on active devices and increase circuit efficiency. The phase shift PWM operation is used to control the active devices of three-level converter. The leading-leg switches are easily turned on under ZVS operation. The presented circuit has less component counts with better circuit efficiency to achieve 10:1 wide voltage operation when compared to conventional two-stage DC converters. The proposed converter has much wider input voltage operation range as compared to conventional single-stage DC converters with 2:1 or 4:1 voltage range (10:1 voltage range from 80 V~800 V). The paper is organized, as follows. Section 2 discusses ...
