Performance of MOSFET Driven via a Bootstrap Capacitor for Dynamic Load Continuity Enhancement

Abstract

In this paper, the operation and a complete design of the bootstrap circuit elements when firing a high-side MOSFET feeding an inductive load are introduced. The operation for both low-side and high-side cases are discussed with complete design and analysis of the bootstrap circuit elements. The effect of the bootstrap capacitor (BSC), diode, and resistance on the MOSFET switch for inductive loads at different frequencies and duty cycles including regular and SPWM are briefly analyzed. The current discontinuity is associated with higher losses, discontinued power output operation, and derated performance. The precise good design of the bootstrap circuit elements enables to improve the load current continuity in a specified frequency range of operation preventing the demerits of discontinuous operation. The effect of high-side implementation on extra harmonic content on the load is discussed including THD measurement of both applied voltages and currents.