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Your search keyword '"Chiang Loh, Poh"' showing total 12 results
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12 results on '"Chiang Loh, Poh"'

2. A variable band universal flux/charge modulator for VSI and CSI modulation

Author

Chiang Loh, Poh and Grahame Holmes, Donald

Subjects
Electric inverters -- Design and construction, Modulators (Electronics) -- Design and construction, Switches -- Design and construction, Business, Computers, Electronics, Electronics and electrical industries
Abstract

This paper presents an integrated approach for closed-loop control of the output voltage of a voltage-source inverter and the output current of a current-source inverter, using hysteresis with a rectangular bounding box in the synchronous d-q reference frame and a simple set of switching rules. The modulator is constrained to only select from the two nearest active space vectors to the target reference, and hence achieves a significantly improved harmonic performance compared to Sigma-Delta and other stationary frame hysteresis modulators. A further refinement then adjusts the dimensions of the bounding box to restrict the switching process to two active space vectors (and null vectors) only within a constant switching period. This achieves a harmonic performance similar to open-loop space-vector modulation. Discontinuous modulation can also be implemented using an alternative dimension-varying strategy and, since the modulator is a closed-loop system, it exhibits excellent robustness to parameter variations and other system disturbances. The practicability and performance of the modulator under various modulation conditions have been verified both in simulation and experimentally. Index Terms--Current control, harmonic analysis, hysteresis, pulsewidth-modulated inverters, Sigma-Delta modulation, voltage control.

Published
2002

12. Single stage buck-boost DC-AC neutral point clamped inverter.

Author

Wei, Mo, Chiang, Loh Poh, Andrew, and Blaabjerg, Frede

Abstract

This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence, it has enhanced buck-boost functionality and low output voltage distortions compared to the traditional Z-source inverter; it has continuous input current which reduces the source stress and inverter noise; it also contains two built-in capacitors which can block the DC current in the transformer windings thus preventing the core from saturation; lowers the voltage stresses and power losses of inverter switches and reduces the sizes of filtering devices and as well as obtains better output performance compared to the original two-level Z-source inverters. A phase disposition pulse width modulation technique with minimum switching counts is implemented for the proposed topology. Simulation results as well as experimental results are presented to verify the behaviors of proposed configuration. [ABSTRACT FROM PUBLISHER]

Published
2012
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