| Non-linear components such as diodes and power transistors in the switching converter cause the circuit to exhibit strong nonlinear characteristics and generate a large number of harmonics.These instabilities,such as sub-harmonic oscillations,fast-scale bifurcation and chaos,make the converter unstable.Therefore,the stability control strategy of switching converter needs to be further studied.This paper takes the PFC Boost converter controlled by peak current as an example to analyze the mechanism of the instability of the converter.For the problem that the grid voltage cannot be consistently stable within a certain fluctuation range and the conventional constant slope compensation method has zero current dead-zone and low power factor due to over-compensation,a dynamic slope compensation strategy is used to provide the converter with consistent stability and approximate unit power factor over the 220 V input voltage and ±20% fluctuation of the power supply voltage.Main work and achievements in the thesis are as follows:a.The design of circuit cannot achieve uniform stability in the wide input voltage range in the past research experiment.Based on the theory of resonance parametric perturbation,the paper adopts dynamic slope compensation method to dynamically adjust the compensation amplitude according to the input and output voltage,and continue to study the compensation effect of the dynamic slope compensation method under wide input voltage.b.In this paper,the circuit of 220V±20%/400 W PFC Boost converter is simulated by Simulink and the prototype is manufactured for testing.The simulation and test results show that the dynamic slope compensation overcomes the shortcomings of the traditional constant slope compensation,and can work stabily within the ±20% fluctuation range of the 220 V input voltage to achieve an approximate unit power factor,which verifies the correctness of the compensation strategy. |
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