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14 results on '"Shi, Zhang Hai"'

11. Simulation Research of the Matrix Converter Based on Direct Torque Control

Author

Shi Zhang-hai and Ka Wai Eric Cheng

Subjects
Rectifier, Engineering, Direct torque control, business.industry, Control theory, Electronic engineering, Inverter, Topology (electrical circuits), Power factor, Matrix converters, business, Space vector modulation, Machine control
Abstract

To advance the performance of AC adjustable speed system and to reduce the pollution to power network, this paper proposes a compound control strategy which combines matrix converter (MC) and direct torque control (DTC). The MC controlled by this strategy cannot only achieve DTC to a asynchronous machine but also acquire good input currents and adjustable power factor. The principle of this strategy is: firstly transform MC into an equivalent topology that is a combination of a rectifier and an inverter, and then perform DTC on inverter and current space vector modulation on the rectifier, at last combine two sides' strategies and change them into the control signals of the MC's nine bidirectional switches. A simulation about MC driving asynchronous machine has been done and the results prove that the strategy proposed by this paper is not only feasible but also excellent.

Published
2006

14. Formulation of buffer energy and experimental results of energy factor of DC-DC converters.

Author

Shi, Zhang Hai, Cheng, Ka Wai Eric, and Ho, Siu Lau

Subjects
*CASCADE converters, *REACTIVE power, *ENERGY storage, *LYAPUNOV functions, *ELECTRIC inductors
Abstract

ABSTRACT Two concepts of buffer energy and energy factor for switched-mode power converters are proposed and examined. They can describe the nonactive power as well as predict and evaluate the performance of DC-DC converters. The concepts can also find usage in both DC and AC systems. The energy factors of six basic topologies of DC-DC converter have been studied, and they can be used to compare the performance of different topologies. It can be shown that both buffer energy and energy factor provide an alternative understanding of the energy processes in DC-DC converters. Experimental results demonstrate that energy factors and buffer energy can be measured. The measured results for some basic converters are consistent with the theoretical values. Buffer energy, energy factor, and their related concepts proposed in this article have promising application in the design of DC-DC converters. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2013
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