Quadrilateral Current Mode Paralleling of Power MOSFETs for Zero-Voltage Switching

Abstract

This paper proposes a generic zero-voltage switching (ZVS) scheme for parallel power MOSFETs. Uncoupled or inversely-coupled differential-mode (DM) commutation inductors are added to the midpoints (AC terminals) of parallel MOSFET half-bridges (HBs), and a time-delay-based control scheme is applied, generating a circulating current flowing through these commutation inductors. Thus, the inductor currents are reshaped as quadrilaterals, which enable all the parallel transistors to achieve ZVS. The mode of operation of the proposed paralleling technique is entitled quadrilateral current mode (QCM) due to the quadrilateral-shaped commutation inductor currents. The operating principle of the QCM-paralleling technique is detailed mathematically, yielding accurate closed-form analytical expressions for modulation parameters. Finally, simulations and experimental results of a QCM-enabled synchronous Buck dc-dc converter are presented to validate the theoretical considerations. Index Terms-Parallel power MOSFETs, zero-voltage switching (ZVS), quadrilateral current mode (QCM)

Split Parallel Semibridge Switching Cells for Full-Power-Range Efficiency Improvement

“…δ on , and T 23 , i.e. δ of f , are determined by (28) and (29). Due to the existence of resonant transitions, the time delays of the rising and falling MOSFET gate signals are not equal to δ on and δ of f , as shown in Fig.…”

“…A comprehensive comparison among the TCM scheme for synchronous Buck converters [18], the DCM scheme for semi-bridges [16], the QCM solution [28], the ARCP method [22], and the proposed PCI-based parallel scheme is shown in Table III. Various performance metrics, including the output current ripple, switching frequency, efficiencies at light and heavy loads, and dependence on auxiliary devices and load.…”

“…In [28], a soft-switching solution named quadrilateral current mode (QCM) operation based on paralleling HBs is proposed which can achieve all the mentioned merits simultaneously in partial load conditions by utilizing a circulating current between parallel HBs. However, the QCM solution is not validated for semi-bridge switching cells and dedicated ZVS inductors are required in [28], which increases the complexity and downgrades the power density.…”

“…In [28], a soft-switching solution named quadrilateral current mode (QCM) operation based on paralleling HBs is proposed which can achieve all the mentioned merits simultaneously in partial load conditions by utilizing a circulating current between parallel HBs. However, the QCM solution is not validated for semi-bridge switching cells and dedicated ZVS inductors are required in [28], which increases the complexity and downgrades the power density. Aiming at overcoming the aforementioned issues and to improve the partial-load efficiency of semi-bridge switching cells, a desynchronized parallel scheme, which employs gate signals of the same switching frequency but with different turn ON/OFF delays, is proposed in this article in which (i) two or more paralleling switching cells are split into two groups which are driven independently and (ii) the split outputs of the 2 groups are closely positively-coupled in the output inductor; (iii) a differential mode inductance is established between the switch nodes of the two groups and (iv) a desynchronized modulation scheme is applied to intentionally create current imbalance for the soft-switching purpose, which significantly reduces the switching loss at partial loads.…”

“…Content may change prior to final publication. [18] Semi-bridge DCM [16] QCM Scheme [28] ARCP [22] Proposed Until 2016, he was a Power Electronics Engineer with the General Electric (GE) Power Conversion business in Rugby, UK. He is currently a Lecturer with the University of Cambridge.…”