Abstract
This paper suggests a soft-switching bidirectional three-level DC–DC converter with a simple auxiliary circuit. The proposed converter uses auxiliary LC resonant circuits so that the power switches operate under a soft-switching condition. The resonant operation of the LC circuits makes power switches turn on at zero voltage, eliminating the turn-on switching power losses. The proposed converter improves the power efficiency, not using complex power switching circuits, but using simple LC resonant circuits. The operation of the proposed converter is described according to its operation modes. Experimental results for a 1.0 kW prototype are discussed to verify its performance. The proposed converter achieved the power efficiencies of 97.7% in the step-up mode and 97.8% in the step-down mode, respectively, for the rated load condition.
Highlights
The non-isolated bidirectional three-level DC–DC converter has been widely used for energy storage systems [1,2,3]
The proposed converter reduces switching power losses and improves power efficiency, compared to the previous converters, which operate without any auxiliary circuits, suffering efficiency, comparedlosses
This paper has suggested a soft-switching bidirectional three-level DC–DC converter, which can effectively reduce the switching power losses with a simple auxiliary circuit
Summary
The non-isolated bidirectional three-level DC–DC converter has been widely used for energy storage systems [1,2,3]. Switch voltage stresses are reduced by half as power switches are stressed on half of the full DC-link voltage [2] It can use lower voltage-rated power switches, which have better switching performance than the power switches in the two-level converters [3]. Aside from energy storage systems [4], the bidirectional three-level DC–DC converter has been utilized for ultra-capacitor applications [5] and various electric vehicle charging applications [6,7]. It still has switching power losses as it operates under a hard switching condition [8]. In the case of using metal oxide semiconductor field effect transistors (MOSFETs), the turn-on switching losses are highly increased as the converter operates at high frequency and high output load condition [9]
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