| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 100 === This thesis presents the design and implementation of a DSP-based digital-controlled current-fed full-bridge power factor correction converter. A micro-controller produced by Texas Instruments is used to replace the conventional analog controller. Via the sample-and-hold circuit on the controller, the input voltage, input current and output voltage are respectively sensed. Then the corresponding PWM control signals are produced. The control loops contain the inner current loop and outer voltage loop. In the outer voltage loop, the digital value of the sensed output voltage is compared to the output voltage reference value to produce the error signal. Then the voltage PI controller determines the amplitude of the current command. This current amplitude command, together with the instantaneous input voltage and the average input voltage value, constitutes the current command. Through the PI controller of the inner current loop, corresponding control signals are resulted to achieve power factor correction and voltage regulation. However, due to the second-order harmonic ripples in the input voltage, input current and output voltage, and the switching noise, the accuracy of the sampled signal will affect the power factor, voltage regulation and total harmonic distortion. The sampled signal usually passes through a low-pass filter to filter out the high-frequency noise. However, it will cause the delay of the signal, resulting in phase distortion. That is why the design of a low-pass filter is very important. A first-order low-pass filter is used to meet the design requirements. Finally, a 6-kW converter prototype is implemented and tested to verify the feasibility of the studied topology and control strategy.
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