Design Of Interleaved Power Factor Correction Convertor Based On Microcontroller

Single phase power factor correction (PFC) is an important application of the power electronics technology. Nowadays, PFC converter based on analog integrated circuit has been matured and market-oriented. However, analog solution has several drawbacks such as the lack of flexible configuration and the lack of peripheral scalability. Compared with analog solution, digital PFC converter has more flexible configurations and stronger peripheral scalability. It has become the future technology trends.This study describes the design of an improved digital controlled PFC converter. On the basis of the classic Boost topology, interleaved topology is adopted to main circuit to improve efficiency and reduce the input current ripple. For the control method, average current mode has been chosen as the control strategy by comparing the current control method. Design of the digital control system is the key to this study. In order to improve the precision of control system, both the resolution of the ADC and PWM are determined quantitatively. Control system includes the outer voltage loop and inner current loop, in which PI controller is introduced as the loop controller and compensator. Small-signal model of the system is established to obtain the transfer functions of both control loops. At the same time, the transfer function of the digital delay and zero-order holder are taken into consideration, so the mathematical model of the control system is complete. At last, Z transformation is applied to compensate the system and determine the coefficients of the all the digital PI compensators. Plotting result of closed-loop frequency response implies that the overall system performance has been improved after compensation.The simulation and experimental results are given at the last part of the thesis to verify the correctness of the design. The waveform of simulation and experiment shows that under the design conditions, the system can achieve a stable DC output at400V and high power factor, which verifies the correctness of the design.