Resonant gate driver design for high efficiency switching power converter.

摘要

In the modern switching mode DC to DC power supply system, in order to achieve better dynamic performance, smaller volume and less weight, the switching frequency of the converting system has continued to increase in recent decades. With higher switching frequency, frequency dependent power losses increase correspondingly, and thus the power efficiency of the power supply system deteriorates. Reducing switching related losses and improving the power efficiency has become a great challenge.;Switching loss is the dominant source of frequency dependent losses. With impact of parasitic gate resistance and source inductance, the switching speed of the power MOSFET driven by conventional voltage source gate driver (VSD) is limited. With resonant gate driver (RGD), a resonant inductor is introduced to the gate drive system and the power MOSFET is turned-on/off by the L-C resonance network. Type I RGD with zero initial resonant inductor current is able to recover part of the gate driving energy and is suitable for low switching loss applications. Type II RGD or current source gate driver (CSD) with pre-charged initial resonant inductor current is able to achieve the fast switching of power MOSFET and reduces its switching loss. Furthermore, with easily adjustable gate driving current, more flexibility can be obtained in the gate driver design.;In this dissertation, impact of parasitic gate resistance and source/drain inductance on the switching process of gate drivers is analyzed. Then, the body diode clamping effect that occurs in the current source gate driver is discussed. Next, the high dynamic range current source gate driver (HD-CSD) is proposed to eliminate the body diode clamping effect and further improve the power efficiency. Detailed operation processes of different types of gate drivers are analyzed and compared. An analytical model is built to predict driver operation and switching power losses of current source gate drivers. Test prototypes are built based on the synchronous buck converter and the boost converter with both low voltage and high voltage power MOSFETs. In order to keep low peak reverse recovery current and EMI while reducing the switching loss, an adaptive gate driver is designed which combines the VSD and HD-CSD. Experimental results that evaluate the power efficiency improvement of the proposed resonant gate drivers are presented.