New, efficient, low-stress buck/boost bidirectional DC-DC converter

Abstract

Bidirectional dc-dc converters (BDCs) are used in many applications when bidirectional energy transfer between two DC buses is needed. They are used as an interface circuit between ultra-capacitor and DC bus in a Hybrid Electric Vehicle (HEV). Since the voltage levels of the ultra-capacitor and DC bus are different, the interface circuitry must be able to increase or decrease the voltage level in each power flow direction while limiting the current. This paper presents a new bidirectional converter employing Gallium Nitride (GaN) power transistors in which Zero-Voltage-Transition (ZVT) switching is provided for all switches to dramatically reduce the switching losses regardless of power flow direction. The soft-switched GaN power transistors result in a significant increase in the efficiency of the new converter compared to that of conventional hard-switched bidirectional converters. Because of low conduction losses, and reduced current and voltage stresses the proposed converter is scalable to higher power levels. Reduced current ripple increases the ultra-capacitor life time. The operation of the converter is discussed in detail and verified using circuit simulations; the efficiency of the new converter is compared with the conventional bidirectional converters.

Thyristor‐based flexible ac transmission system for controlling the vanadium redox flow battery

“…The reactive power fluctuations generated by the TCCC are compensated by the DFIG generator. In addition, the use of the TCCC instead of the DSTATCOM provides the following advantages: (i) for the same rated power, the capital cost of a TCCC is ∼20–30% of the capital cost of a DSTATCOM [9–11], (ii) for power ratings above 1 MW, the TCCC provides a higher efficiency than the DSTATCOM (from 85 to 99%) [6–11, 32, 33] and (iii) the proposed PCS is less complex than the typical PCS because of the dc/dc converter can be avoided.…”

“…However, the use of the DSTATCOM presents several disadvantages: (i) a dc/dc converter is required between the VRB and the VSC [2][3][4][5], (ii) the system complexity increases and the efficiency of the PCS decreases [6][7][8] and (iii) the high cost of IGBT switches increases the PCS capital cost [9][10][11]. In this regard, this paper proposes a new FACTS compensator based on a 12-pulse bidirectional thyristor converter for controlling the exchange of active power flow between the VRB and the grid.…”

Open‐loop transfer functions of buck–boost converter by circuit‐averaging technique

“…The applications of buck–boost dc–dc converter are becoming much evident these days in automotive electronics for bidirectional power transfer [8], solar photovoltaic panels [9], and as power and amplitude modulators for radio‐frequency power amplifiers [10], citeRP. For the purpose of designing closed‐loop responses for buck–boost converters, which could be potentially used in these applications, the small‐signal dynamic model of the converter becomes essential.…”