Novel Current Measurement Concept for Half Bridge Topologies Based on Simple-to-implement Digital Current Observer

Abstract:
Measuring devices are required to ascertain voltage and current data in controlled power electronic converters. The voltage can be measured easily and cost-effectively with the suitable high impedance operational amplifier circuits, while the current determination is becoming more challenging due to the increase in the switching frequency of modern (GaN-) converters. This paper presents a novel and an efficient current sensing scheme with a simple-to-implement digital current observer that estimates the inductor current of a half bridge by using available signals from digital closed-loop control in combination with basic DSP peripherals. The practical implementation, based on a standard low-cost DSP, will have less negative influence on switching characteristics of the switches, reduces the inductance in commutation path, and decreases the size and cost of the overall system.