Three-level buck circuit control method, charger circuit control method and system

Abstract

The invention relates to a three-level BUCK circuit control method, a charger circuit control method and a system. By performing PID closed-loop voltage control on two equalizing capacitors of the three-level BUCK circuit, the output voltage of each equalizing capacitor is U in / 2, correct the PWM duty cycle of the two switching tubes; at the same time, take the feed-forward voltage compensation value of the three-level BUCK circuit as the given voltage target value of the resonant conversion circuit, and perform PID closed-loop voltage control on the resonant conversion circuit to correct The switching tube PWM duty cycle of the resonant conversion circuit. In the present invention, by increasing the voltage equalizing closed-loop control, the voltage of the equalizing capacitor at the front end of the three-level BUCK circuit is ensured to be evenly divided. At the same time, increasing the voltage closed-loop compensation of the resonant conversion circuit ensures the effectiveness of the resonant circuit, eliminates the influence of the low-frequency ripple of the three-level BUCK circuit on the output voltage, stabilizes the output voltage, and improves the relationship between the BUCK circuit and the subsequent resonant circuit. Coupling control.

Description

technical field [0001] The invention belongs to the technical field of charger circuit control, and in particular relates to a three-level BUCK circuit control method, a charger circuit control method and a system. Background technique [0002] The existing charger circuit mainly includes a three-level BUCK circuit, a resonant conversion circuit, and an output rectification filter circuit. The three-level BUCK circuit performs voltage equalization and voltage stabilization control. circuit for rectification and filtering, such as figure 1 Shown is the topological structure of the main circuit of the charger circuit. [0003] The existing three-level BUCK circuit mainly collects the three-loop control method of the voltage outer loop, the current inner loop, and the voltage equalizing loop. The voltage equalizing loop adopts open-loop control, and the voltage U1 on the output capacitor C1 and the voltage U2 on the output capacitor C2 are collected for differential transmissi...

AI Technical Summary

Problems solved by technology

In this three-loop control method, due to the different switching characteristics of the switching tubes Q1 and Q2, the voltage equalizing loop adopts open-loop control, and the difference between the voltages of the two output capacitors is used as the feedback value, which cannot effectively guarantee the output voltage of the equalizing capacitors C1 and C2. balance control

At the same time, the open-loop control method is commonly used in the post-stage resonant conversion circuit, but due to the voltage fluctuation of the DC blocking capacitor FC brought about by the voltage equalization control of the output capacitors C1 and C2 of the three-level BUCK circuit, coupling to the output terminal of the resonant circuit may easily cause the output voltage to exist. Low frequency pulsation

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