Self-contained control for turn-on transition of an optically driven IGBT

This paper presents a novel photonic control mechanism to control the turn-on transition of insulated gate power semi-conductor devices (PSDs), used in the hard switched power electronics applications. Turn-on transition control decreases the overshoot of the turn-on current caused by reverse-recovery current (IRR) of the free-wheeling diode (FWD) due to high slope of current during turn-on. It also adjusts the turn-on dv/dt to control the switching loss and electro-magnetic interference (EMI) while keeps the PSD in the safe-operating area. In contrast to other works, the proposed control method independently adjusts the turn-on di/dt and dv/dt in different operating conditions using a single circuit. The onset of transition between di/dt and dv/dt control regions is determined using a self-contained control circuit. The error between the desired and actual onset of transition is compensated using a partially activated PI compensator. Another feature of the presented work is using a single optical link for both pulse-width modulation (PWM) and switching transition control of an Optically-triggered (OT) hybrid device comprising an IGBT as the main PSD and a pair of GaAs-based optically-triggered power transistors (OTPTs) serving as the driver for the IGBT. The proposed control circuit operation and advantages are presented and verified by experimental results.