Analysis and Implementation of Zero Voltage Switching for Class E Inverter under Dynamic Load
Mao Ling1, Yin Yifan1, Zhao Jinbin2, Kong Dele1, Zhang Junwei1
1. College of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 China; 2. Engineering Research Center of Offshore Wind Technology Ministry of Education Shanghai University of Electric Power Shanghai 200090 China
Abstract：The Class E inverter stands out due to its simple structure and application of resonant inverter technology, allowing it to operate stably in a zero voltage switching (ZVS) state. This characteristic significantly reduces switching losses, improves overall system efficiency, and effectively mitigates common penetration risks, making the circuit more reliable in high-frequency operating environments. However, maintaining the ZVS state of the Class E inverter under variable load conditions poses significant challenges, leading to considerable losses and imposing serious limitations on its application scenarios. Therefore, reducing the load sensitivity of Class E inverters is a key issue. This paper fully utilizes the continuous conduction characteristics of the MOSFET body diode to expand the feasible ZVS operating area of the Class E inverter. In-depth analysis shows that the ratio β between the input DC current I and the amplitude of the output current Im? of the Class E inverter is significantly correlated with the range of load variation under ZVS conditions. This insight has led to the proposal of a parameter design scheme for the Class E inverter that can adapt to the range of dynamic load variations. First, this paper analyzes the operating process of the Class E inverter based on voltage and power balance and establishes a mathematical model. Subsequently, the body diode of the MOSFET is utilized to expand the feasible ZVS operating area of the Class E inverter. Building on this, the paper analyzes the characteristics of the switch voltage waveform changing with load variations. The analysis demonstrates that the value of parameter β significantly impacts the trajectory of the operating point of the Class E inverter within the ZVS feasible region. Subsequently, the paper conducts a comparative analysis of the peak voltage, peak current, and output power capabilities at different operating points. Finally, based on the results of the aforementioned analysis, this paper proposes a design scheme for the parameters of the Class E inverter that can accommodate a dynamic range of load variations. Based on the theoretical analysis presented above, this paper builds an experimental prototype with a rated load of 40 Ω and a load variation range of ±20%. When the load resistance is 32 Ω, 40 Ω, and 48 Ω, the theoretical peak voltages are 173.2 V, 159.2 V, and 146 V, respectively. The simulation results are 169.6 V, 161.5 V, and 153.7 V, respectively, while the experimental results are 167 V, 158 V, and 148 V, with errors of approximately -3.58%, -0.75%, and 1.37%. At the same time, the peak efficiency of the experimental prototype is 85.6%. These results validate the feasibility of the proposed parameter design scheme and demonstrate that the approach suggested in this paper can expand the load variation range while reducing switching losses under ZVS conditions in Class E inverters, thereby improving system efficiency. The following conclusions can be drawn from the simulation and experimental analysis: (1) Utilizing the body diode characteristics of osfet can expand the feasible range of ZVS. It has been found that the smaller the ratio β, the broader the range of load variations it can accommodate. (2) By selecting suitable parameter β, the Class E inverter can maintain ZVS operation within a certain range of load variations. Meanwhile, this paper provides a design scheme that meets the load variation range. (3) Simulating and experimentally validating the proposed design scheme within a ±20% range of load variations demonstrates the feasibility of the scheme, and the peak efficiency of the entire system reached 85.6%.
毛玲, 尹伊凡, 赵晋斌, 孔德乐, 张俊伟. 动态负载下E类逆变器零电压软开关分析及实现[J]. 电工技术学报, 2025, 40(7): 2203-2214.
Mao Ling, Yin Yifan, Zhao Jinbin, Kong Dele, Zhang Junwei. Analysis and Implementation of Zero Voltage Switching for Class E Inverter under Dynamic Load. Transactions of China Electrotechnical Society, 2025, 40(7): 2203-2214.
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