A dc-link voltage stability analysis technique for hybrid five-phase open-end winding drives

This paper studies the dc-link voltage stability for a hybrid five-phase open-end winding (OeW) drive operating under carrier based (CB) pulse-width modulation (PWM). The drive consists of a five-phase induction machine, supplied using one three-level and one two-level voltage source inverter (VSI). This configuration is analysed for the case of isolated dc-link rails, while dc-link voltage ratio is considered as an additional degree of freedom. It is demonstrated that different dc-link voltage ratios lead to the different overall number of voltage levels across stator windings. Modulation strategies are investigated and their performances are analysed from the dc-link voltages stability point of view. An analytical method for dc-link voltage stability analysis is presented. Results show that the four-level configuration always leads to stable dc-link voltages, regardless of the modulation strategy. On the other hand, if six-level configuration is combined with modulation strategies that lead to an optimal harmonic performance, not all dc-link capacitor voltages will be in balance depending on the operating conditions

Active Resistance Emulation in Three-Phase Rectifier with Suboptimal Current Injection

<p>In this paper, suboptimal current injection in three-phase diode bridge rectifiers that apply switching resistance emulators is analyzed. Two rectifiers are focused, one that applies filtering of the resistance emulator output current, and the other one that does not. Models that cover both the continuous and the discontinuous conduction mode of the rectifiers are developed. Optimization is performed, showing that both of the rectifiers provide about the same performance when the emulated resistance takes the optimal value. The results are experimentally verified.</p