A High-Efficiency Voltage Equalization Scheme for Supercapacitor Energy Storage System in Renewable Generation Applications

Abstract

Due to its fast charge and discharge rate, a supercapacitor-based energy storage system is especially suitable for power smoothing in renewable energy generation applications. Voltage equalization is essential for series-connected supercapacitors in an energy storage system, because it supports the system's sustainability and maximizes the available cell energy. In this paper, we present a high-efficiency voltage equalization scheme for supercapacitor energy storage systems in renewable generation applications. We propose an improved isolated converter topology that uses a multi-winding transformer. An improved push-pull forward circuit is applied on the primary side of the transformer. A coupling inductor is added on the primary side to allow the switches to operate under the zero-voltage switching (ZVS) condition, which reduces switching losses. The diodes in the rectifier are replaced with metal-oxide-semiconductor field-effect transistors (MOSFETs) to reduce the power dissipation of the secondary side. In order to simplify the control, we designed a controllable rectifying circuit to achieve synchronous rectifying on the secondary side of the transformer. The experimental results verified the effectiveness of the proposed design.

Design of a Bidirectional Energy Storage System for a Vanadium Redox Flow Battery in a Microgrid with SOC Estimation

“…Besides, the charging time is longer than the discharging time, as the charging time is about 5 h and the discharging time is about 4 h. This is because the stack power in a discharging state is more expended. In Figure 14, the actual value of the SOC was obtained by Equation (4). As can be seen from Figure 14, the proposed SOC estimation method is very effective, as the estimation value of the SOC is very close to the actual value of the SOC.…”

“…In [4,5], a control strategy of an ESS, based on a bidirectional DC-DC converter for a novel stand-alone photovoltaic power system, was proposed. But, this ESS was connected to a DC bus, without considering the power flow between the energy storage battery and the AC grid, resulting in great limitations for the energy storage system.…”

“…Recently, many researchers have concentrated on the design of a VRB energy storage system [4][5][6][7][8][9][10]. In [4,5], a control strategy of an ESS, based on a bidirectional DC-DC converter for a novel stand-alone photovoltaic power system, was proposed.…”

Design and Modeling of an Equalizer for Fuel Cell Energy Management Systems

“…The converter based equalizer can be categorized into three groups: cell to stack equalizers [4], stack to cell equalizers [13], [19]- [25], stack to stack equalizers [26], and cell to cell equalizers [14]- [18].…”

Bidirectional Interleaved PWM Converter with High Voltage-Conversion Ratio and Automatic Current Balancing Capability for Single-Cell Battery Power System in Small Scientific Satellites

“…To ensure years of safe operation of batteries consisting of multiple cells connected in series, a cell equalizer is indispensable to mitigate or even eliminate cell voltage imbalance. Cell equalizers are essentially a switching power converter, such as nonisolated bidirectional converters [2][3][4][5], single-input multi-output converters [6][7][8][9], etc. [10], and these add complexity to spacecraft power systems.…”