MSU Technologies

High Efficiency Power Transistor Gate Drive

Introduction

Gate-drive technology is traditionally an open-loop passive method that has no real-time control of a semiconductor power device’s switching speed, overshoot, and switching power losses. The technology is unreliable and cannot be optimized over different operating voltages and current conditions. It suffers high transient overshoots at voltage and current if gate resistance is reduced to minimize the switching loss. A technology that can decouple the two issues with a satisfactory solution is needed.

Description of Technology

Michigan State University’s invention provides a current source-based, active, gate-drive circuit for power transistors such as IGBT (insulated-gate bipolar transistor) and MOSFET (metal oxide semiconductor field-effect transistor). The circuit consists of a current source to accelerate the change rate of voltage to reduce the switching loss, and a voltage-controlled current source to keep the change rate of the current at a proper level to limit the transient overshoots. The voltage signal used to control the current sources is derived from the change rate of the device current.

For example, during IGBT turn-on, the gate drive signal turns on the current source to charge up the gate voltage. Once the gate voltage reaches its steady state value, the current source gate driver is cut off to keep the gate voltage in its steady state value. Though the current source has a constant value, its amplitude can also be changed during the turn-on period.

Key Benefits