Low-Ripple Low-Transition Time, Current Driver for Large Inductive Loads

The paper presents a precision current driver for electron-beams steering coils. The proposed current driver provides an effective solution to the applications requirements: fast current changes in the coil inductor and very accurate low-ripple steady-state current (<0.06%), together with high power density. The power converter circuit is based on the use of two operating voltage levels. A high voltage is used for a fast transition to the required current level, and a low voltage is used to provide steady state precise regulation with low current ripple. The paper presents a solution using two voltage supplies that requires only one high frequency switching device, and also proposes alternative circuit solutions that require only a single input supply and generate internally the required voltages as part of the normal circuit operation. The experimental results to verify the correct circuit operation were obtained on a prototype built with low conduction loss IGBTs, a MOSFET for high frequency switching, and SiC diodes that allow minimal perturbation when transitioning from high voltage to low voltage