Development of a Bidirectional DC–DC Converter with Rapid Energy Bidirectional Transition Technology

Abstract

Bidirectional DC–DC converters are key devices in the DC distribution system and the energy storage system (ESS). It is important to consider the safety of the elements in the converter for rapid conversion of the power direction. Damages may occur to the power-related components in the circuit if the direction of the inductor current or the capacitor voltage changes instantaneously. To make the power flow change smoothly and quickly, this research proposed a bidirectional DC–DC converter with rapid energy transition technology implemented in the circuit architecture. The rapid energy bidirectional transition technology added a resonance path based on the LC resonant circuit, allowing rapid energy conversion through the resonance path. Therefore, the energy in the energy storage element could be quickly converted without causing circuit surges. Analyses of the converter operating in the step-up mode, the step-down mode, and the transition operation mode are presented. The proposed circuit architecture had a high voltage-conversion ratio and a simple architecture. A prototype bidirectional DC–DC converter with a full load of 500 W, a low side voltage of 24 V, and a high side voltage of 200 V was developed to prove the concept. The feasibility of the rapid energy bidirectional transition technology was verified by the simulation results and experimental results using the prototype converter. The maximum efficiencies in the step-up mode and the step-down mode were 95.3% and 93.8% respectively. Under full-load conditions, the transient time of the energy transition from the step-up mode to the step-down mode was 17.7 μs, and the transient time of the energy transition from the step-down mode to the step-up mode was 19.3 μs.

A Step-Up Converter with Large Voltage Gain and Low Voltage Rating on Capacitors

“…We can make some remarks about the obtained result. The voltage gain expressed in (12) is the same as that for the previous converter (the one in Figure 1). Both converters offer a larger voltage gain compared with a traditional boost converter for the same duty cycle.…”

“…However, an advantage is that capacitors sustain a lower voltage in the proposed converter. Figure 6 shows two graphs: (i) In blue, the voltage gains of the converter as a function of the duty cycle-which is basically (12) divided over the input voltage V g for the former topology-is the same as the voltage in the output capacitor since the output capacitor sustains the output voltage; (ii) in red, the function of the voltage across capacitors of the proposed converter-basically (10) or (11) divided over the input voltage V g -is shown to be substantially smaller than the blue graph. We can observe the stored energy in a capacitor is proportional to the square of its voltage, for which a reduction in the voltage of a capacitor would result in a reduction in stored energy.…”

“…Figure 1 shows a recent contribution, a converter introduced in [9] with two equal inductors that are charged in parallel and discharged in series, splitting the power into two paths with a low parasitic resistance. Due to its advantages, its structure has been used as a base to develop other topologies [9][10][11][12][13].…”

“…Figure 1 shows a recent contribution, a converter introduced in [9] with two equal inductors that are charged in parallel and discharged in series, splitting the power into two paths with a low parasitic resistance. Due to its advantages, its structure has been used as a base to develop other topologies [9][10][11][12][13]. This paper introduces a two-transistor-based, transformer-less DC-DC converter topology whose main advantages are: (i) it provides a large-voltage gain without the use of an extreme duty cycle; (ii) its capacitors require a smaller voltage to be sustained compared with other similar, state-of-the-art converters; (iii) the voltage among the ground input and output is not pulsating; and (iv) it can be synthesized with commercial, off-theshelf half-bridge packed transistors if synchronous rectification is preferred.…”

Polytopic Robust Stability for a Dual-Capacitor Boost Converter in Symmetric and Non-Symmetric Configurations

“…The topology studied in this paper and shown in Figure 1 effectively reduces the volume and cost of having a (big) single-output capacitor (see, for example, [9][10][11]); this is achieved by lowering the voltage rating because of a symmetric connection of two capacitors. Although other double-series unidirectional capacitor topologies were presented in [12], the configuration used in this paper requires only two switches, can be expanded for bidirectional usage (adding two more switches), and provides significant voltage gain from moderate duty cycles, thus reducing conduction losses.…”