一种碳化硅与硅器件混合型三电平有源中点钳位零电压转换软开关变流器

Improving power density and efficiency is a current development trend in the new energy generation system. This objective can be achieved by reducing system switching losses and increasing switching frequency. Compared with silicon (Si) devices, silicon carbide (SiC) wide bandgap semiconductor devices have the advantages of low losses and high junction temperature, which can effectively improve the efficiency and switching frequency of converters and have emerged as a prominent topic in recent academic research. However, the cost of SiC devices is still several times higher than that of Si devices. As a result, realizing an all-SiC converter in the three-level active-neutral-point-clamped (3L-ANPC) topology for cost reasons is challenging. Consequently, the industry has proposed a hybrid configuration incorporating SiC and Si devices to enhance converter efficiency and power density and control costs. In addition, the use of SiC-wide bandgap semiconductor devices can lead to severe switching overvoltage and electromagnetic interference issues. Furthermore, at higher switching frequencies, such as 100 kHz, the hard-switching losses with SiC devices can be significant, hindering further improvements in converter efficiency and power density. As a solution to these challenges, researchers have proposed the use of soft-switching technology. A hybrid 3L-ANPC zero-voltage transition (ZVT) soft-switching converter based on SiC and Si devices was proposed. Based on the two SiC MOSFET devices’ hybrid 3L-ANPC converter topology, the main circuit SiC devices and the auxiliary circuit Si devices can achieve soft-switching in the full power range with an auxiliary circuit, thus improving converter efficiency while considering its economy. Firstly, the circuit topology and working mechanism of the proposed 3L-ANPC ZVT soft-switching converter were illustrated. The main circuit's modulation strategy is designed to operate the outer switches and clamping switches in the line frequency. The inner switches operate at high frequency to leverage the benefits of the high-speed switching of SiC MOSFETs and concentrate the switching losses on the inner switches. The auxiliary circuit only works during the switch transition process to assist the inner switches in achieving ZVT and reducing switching losses. Secondly, an optimized design process was formulated for the auxiliary switching timing and auxiliary circuit parameters to facilitate the successful implementation of soft-switching in practical applications. Thirdly, the switching and commutation characteristics of the devices were obtained under hard-switching and soft-switching conditions by double-pulse test. Based on the experimental results. A loss model for the converter was built, and a comparison was conducted between the distribution of losses and the efficiency changes of the soft-switching converter and a traditional hard-switching converter. Finally, an experimental platform of 10 kW/100 kHz was established to verify the proposed 3L-ANPC ZVT soft-switching converter. The theoretical analysis and experimental results show that the proposed 3L-ANPC ZVT soft-switching converter can improve the efficiency of the converter at a switching frequency above 20 kHz, increasing the efficiency from 96.63% of the hard-switching to 97.42% at the switching frequency of 100 kHz.