A Comparative Study of SVPD-PWM and Multiband Hysteresis Through Digital Implementation for A Type-G Converter

In last decades, aiming to control some processes and improve high power systems efficiency, multilevel converters have commonly been used in adjustable speed and high-performance drives in the mining industry. Although they present operational advantages over the classic two-level topology in high power and medium voltage applications, current control employed for them has yet some issues that deserve additional studies. In this line, this work presents a comparative study of two current control techniques for a five-level Neutral Point Clamped (NPC) induction motor drive: (i) linear current control with SVPWM command (commonly applied in commercial drives) and (ii) non-linear digital hysteresis current control. A multiband switching frequency limiter is proposed in this paper for the last technique. The multilevel power electronic converter investigated here is an NPC converter known as Type G converter. Some challenges for implementation of digital multiband hysteresis are discussed. In this paper a digital signal processor (DSP) is proposed for both strategies, while a field programmable gate array (FPGA) is employed to implement the frequency limiting circuits and switching logic of the digital hysteresis control. In both cases, the drive operates under rotor field-oriented control (RFOC). Results obtained from Simulation in PLECS™ are presented and discussed.