On the Damping of Ringing Affecting Power Transistors by Means of Active Gate Drivers

Fast power transistors require a tight control of their switching trajectory to exploit them at full speed, without degrading reliability and delivered electromagnetic emission figures of merit. By using active gate drivers in place of conventional ones, the switching trajectory can be shaped to reduce current and voltage overshoots, as well as the amplitude of oscillations. However, the tuning of such drivers is still an open issue. This paper investigates the damping of oscillations by means of active gate drivers, and proposes a method to tune them a-priori . The target switching waveforms are evaluated by means of non-linear damping elements in simulation, easing the tuning procedure. The proposed method was assessed on a digital active gate driver, providing the initial set-point for the adaptive controller. The convergence time measured experimentally was found to be as low as 50for the overall load current range, whilst not affecting the conversion efficiency of the dc-dc converter exploited as test case.