功率MOSFET并联主动均流设计与仿真

功率MOSFET并联在低压大电流领域是一种常见而且有效的解决方案。但是，由于MOSFET器件参数、回路寄生参数以及栅极驱动参数的差异性等因素，功率MOSFET器件并联时常常出现电流不均衡现象。通过Multisim 仿真，分析了MOSFET器件参数因素以及外围电路特性对并联支路静态和动态电流的影响；根据法拉第电磁感应定律以及磁通约束原理，采用耦合电感的均流方法，在并联的各支路中串入共磁芯耦合线圈，实现了各并联支路的电流平衡；然后，通过建立耦合电感的电路以及数学模型，揭示了串入耦合电感实现均流的数学原理。最后，通过仿真验证了串入耦合电感实现并联功率MOSFET均流方法的有效性与可行性。

Design and Simulation of Active Current Sharing of Paralleled Power MOSFETs

Parallel connection of MOSFET devices is an available solution for low-voltage and high-current field. But the current sharing among paralleled power MOSFETs is hardly realized, on account of the parameter variations of MOSFETs, the uneven scattered parameters of layouts or packages, and the different parameters of gate-drive and so on. The paper analyses the characteristic parameters of MOSFET and effects of circuit parameters on the static and dynamic drain current with Multisim. In this paper, the current balance of each parallel branch is realized by adopting the current sharing method of coupling inductor, which is to connect coupling coils of common magnetic core in series in each branch of parallel connection, according to Faraday''s law of electromagnetic induction and the principle of flux constraint. Then, the circuit and mathematical models of coupling inductors are presented to reveal its mechanism to eliminate the unbalance current actively. Finally, the effectiveness and feasibility of the current-sharing method for parallel power MOSFET with series-coupled inductors are verified by simulation.