| Summary: | 碩士 === 明新科技大學 === 電機工程研究所 === 96 === Over the last several years, there have been some extensive applications of the three-phase controlled rectifier, such as DC motor driver, illumination controls, the charger of the battery, DC supplying device, and the adjuster pre-requlator of the AC motor drivers. Besides, there have also been extensive applications of the high power and big current in industry process control, such as system of electrolysis and electric welding. In the above-mentioned applications, the main requirement produces the DC current source that can be adjusted and controlled in the specified range. This thesis presents the design of a digital control IC which is intended for controlling thyristors to produce a constant current source via a three-phase controlled rectifier. The architecture of the control IC consists of three major parts: a three-phase controlled triggering circuit, an inverse cosine look-up table, and a proportional-integral current controller. All the three parts have been designed using VHDL language and integrated as a control IP (intellectual property). The simulation model for a constant current source based on a three-phase controlled rectifier has also been constructed by using Simulink, ModelSim, and PSIM cosimulation tool. Further, a multiple-sampling and average scheme for the current feedback has been adopted to reduce the current ripple effect. The designed control IC circuit has been implemented on an Altera Flex 10K FPGA logic device. Simulation and experimental result reveal this control IC receives steady dynamic response in changing current reference command and load variation. In addition, the control IC has been applied to control a set of LED lamps. This verifies the feasibility of this current source controller.
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