Resonant DC link soft-switching inverter with low-loss auxiliary circuit

ABSTRACT

An auxiliary switching device is usually set on the DC bus of the resonant DC link inverter, which restricts the efficiency of the inverter and is also one of the reasons for its not extensive application and promotion in the high-power field. To solve the problem, auxiliary circuits and DC bus of the resonant DC link soft-switching inverter designed in this paper are connected in parallel, and auxiliary switching devices and resonant elements are not connected in series on the DC bus, which help to improve the efficiency and reduce the power losses of the auxiliary resonant circuits. Based on the equivalent circuits in different operating modes, the paper analyzes the working process of the soft-switching inverter, soft-switching realization conditions and design rules. A 10 kW laboratory prototype is built, and through the comparison of the experimental results from it and the hard-switching inverter, it is shown that the efficiency improvement value of the designed inverter at full load is higher than that at light load. Therefore, the soft-switching inverter designed in this paper is conductive to reducing the power losses of the auxiliary resonant circuits and ensuring the efficient use of the electric energy.

KEYWORDS:

• Inverter
• soft-switching
• resonant DC link
• auxiliary switches
• switching losses

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (No.51207069), Natural Science Foundation of Liaoning Province of China (No.20170540586) and Scientific Research Cultivation Fund of LSHU of China (No.2016PY-016).