Gate Driver with Overshoot Regulation and Active Snubbing

摘要

Voltage overshoot is regulated by controlling the gate driver. During device turn-off stage, voltage ringing occurs on switching devices due to the resonance between parasitic elements. Improvements can be achieved by slowing down the gate driving speed or by absorbing the energy on passive components. Yet switching loss will increase in these methods. Controls of gate drivers can reduce voltage with less power loss, but the clamping voltage varies with different parameters or operating conditions in the applied circuit. This paper presents a gate driver with overshoot regulation and active snubbing (ORAS). Minimum energy is used to achieve voltage clamping within expected level. It regulates overshoot with controlled gate-signal in the beginning of ringing, so voltage can be clamped by least energy loss. To limit the maximum voltage, a closed-loop controller is used to clamp the voltage under certain level by sensing the peak voltage. Through simulation, ORAS is proven to reduce voltage overshoot from 28 V to 17 V, and regulate Vdsmax within 1 V error during load/ line transient. Compared with other methods in the same level of voltage-clamping, ORAS consumes only half of the energy by using snubber and 1/6 of energy by increasing gate resistor. With precisely overvoltage regulating and minimum energy consuming, a gate driver with overshoot regulator is built. A mathematic model of ORAS is verified and can be applied in compensator design.