Assessment and implementation of an optimized Digital Hysteresis Current Control for a low cost Three-level Boost Rectifier in Metal Industries

Abstract

This work evaluates the digital hysteresis current control of a high power and low cost three-phase and three-level active AC-DC rectifier in metal industries. The rectifier consists of an alternative converter composed of two active semiconductor switches and four power diodes per phase. It implies in a good voltage and current quality and lower maintenance and acquisition costs. In this scenario, the paper presents some important issues related to hysteresis current control operation, which affects the converter semiconductor switching pattern and performance in metal industry applications. The paper shows some good features achieved with the digital implementation of a hysteresis current control. Following this line, it is possible to limit the converter switching frequency and semiconductor stress and reduce the spectral harmonic spreading by digital hysteresis current control when the control system works with low sampling rates. Therefore, by an adequate choice of the sampling rate, the control system can be designed to respect and/or limit stress and losses in the power switches. Besides, the design can also lead the converter to low current ripple levels and an optimized size, weight and price of input inductors. The study is conducted through simulation and experiments. The results obtained reinforce and confirm the proposed ideas.