Slope Compensated Hysteretic Current Control of 800 V 4-Level GaN/SiC ANPC Converter

This work presents hysteretic current control (HCC) of a 4-level active neutral point clamped (ANPC) 650 V GaN and 1200 V SiC converter for up to 800 V operation. Compared to PWM control, HCC enables a direct cycle-by-cycle current control, useful for dynamic charging applications such as required for driving dielectric smart materials. HCC suffers from the limited current sensor bandwidth, which is addressed in this work by a software-based cycle-by-cycle peak/valley current compensation method. From measured high-side and low-side switching durations, a peak/valley correction correction is calculated and applied to the next cycle. At 150 V, for 2-level operation, slope compensation increased the efficiency from 99.13% to 99.19%. 4-level operation (cyclic charging/discharging a 50 µF load at 1 Hz) with slope compensation resulted in 99.57% peak efficiency at 400 V, and over 99.4% efficiency over a wide input voltage range of 100-800 V.