Abstract
Hybrid energy storage systems (HESS) play an important role in maintaining the power balance of a direct current (DC) micro-grid. A HESS is mainly composed of high power density super-capacitors (SCs) and high energy density batteries. According to the operational requirements of an SC, a bidirectional DC-DC converter with the characteristics of a good dynamic response and a wide voltage conversion ratio is needed to interface the SC and a high-voltage DC bus. In this paper, a novel common grounded H-type bidirectional converter characterized by a good dynamic response, a low inductor current ripple, and a wide voltage conversion ratio is proposed. In addition, it can avoid the narrow pulse of pulse width modulation (PWM) voltage waveforms when a high voltage conversion ratio is achieved. All of these features are beneficial to the operation of the SC connected to a DC bus. The operating principle and characteristics of the proposed converter are presented in this paper. A 320 W prototype with a wide voltage conversion ranging from 3.3 to 8 in step-up mode and 1/8 to 1/3 in step-down mode has been constructed to validate the feasibility and effectiveness of the proposed converter.
Highlights
With the high penetration of direct current (DC) energy sources, storage, and loads, DC micro-grids are becoming more prevalent due to a lower number of power converters compared with an alternating current (AC) micro-grid [1,2,3]
This paper presents a novel common grounded H-type bidirectional DC-DC converter, which achieves a wide voltage conversion ratio, and has the advantages of a low inductor current ripple and a good dynamic response
Only one inductor is used in this converter, and the inductor is charged and discharged twice during each switching period, which results in a low inductor current charged and discharged twice during each switching period, which results in a low inductor current ripple and a small size for this converter
Summary
With the high penetration of direct current (DC) energy sources, storage, and loads, DC micro-grids are becoming more prevalent due to a lower number of power converters compared with an alternating current (AC) micro-grid [1,2,3]. In [31], a new non-isolated single capacitor bidirectional DC-DC converter with a simple structure and a wide voltage conversion ratio is presented. This paper presents a novel common grounded H-type bidirectional DC-DC converter, which achieves a wide voltage conversion ratio, and has the advantages of a low inductor current ripple and a good dynamic response. A clamp capacitor is used in this converter to keep all of the power switches turned on and off only once during each switching period, aiming at reducing switching losses and avoiding narrow pulses of the pulse width modulation (PWM) voltage waveform at high voltage gain These features are beneficial to improve the efficiency and reliability of this converter and its suitability for HESS applications.
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