Novel Insights Into Load Current Control Using Power MOSFET

Power MOSFETs are critical in applications involving load current control, where system performance is significantly affected by their operating regions. This paper investigates the operational characteristics of power MOSFETs and proposes a novel approach for load current control based on their transconductance properties. By analyzing the relationship between MOSFET operating regions and load current dynamics, a control strategy that directly regulates the gate-source voltage to achieve precise current control is established. Furthermore, a gate driver circuit is designed to extend the controllable voltage range and enhance sensitivity to drain current variations. To improve current sensing accuracy, a methodology for designing a shunt resistor is introduced, leveraging the theoretical load curve of MOSFETs. Simulations using Simscape models and experimental validation confirm that the proposed method effectively extends the controllable voltage range of the drain current. Specifically, the voltage range can increase by up to 75% under load conditions compared to the absence of a shunt resistor, providing improved flexibility in current regulation. These findings offer novel insights into the use of power MOSFETs for load current control, with potential applications in digitally controlled power systems and motor drives.