Parallel-connection LLC resonant converter frequency-modulated phase shift current sharing control method

Abstract

The invention discloses a parallel-connection LLC resonant converter frequency-modulated phase shift current sharing control method, and the control method mainly uses a voltage loop and a current loop as a supplement. The voltage loop relies on a PFM (pulse frequency modulation) control method to achieve the stable output of voltage; and the current loop utilizes the phase shift control to make the produced phase shift angle exerted on a voltage loop generated signal so as to realize the current sharing between the parallel-connection modules and to prevent the damage to the equipment due to the excessive current of a certain phase under the condition that the system meets the stable output of voltage. The control strategy featuring the combined use of the voltage loop and the current loop not only achieves the stable output of voltage, but also eliminates the uneven current caused by the influence of the electromagnetic parameter errors of the parallel-connection modules or the uneven load distribution, extending the service life of the equipment and playing an importance role in improving the conversion efficiency and dynamic stability of a resonant conversion circuit system.

Description

technical field [0001] The present invention relates to the technical field of power electronics, and more particularly relates to a method for controlling frequency modulation, phase shift and current sharing of parallel LLC resonant converters. Background technique [0002] With the rapid development of my country's economy, the automobile industry continues to heat up. At the same time, the research and development of electric vehicle charging piles should also be included in the development plan. People put forward higher requirements on the volume, power density, and charging efficiency of charging piles. In order to shorten the charging time of cars and improve work efficiency, it is necessary to increase the operating frequency of the converter in the charging pile. [0003] Due to high frequency requirements, soft switching technology has become a research hotspot. As a feasible way to realize soft switching technology, resonant technology can reduce hard switching ...

AI Technical Summary

Problems solved by technology

Although some scholars have done research on the current sharing of LLC resonant converters in parallel, there is still room for development. For example, some scholars have proposed to use external circuits to control the current sharing of each phase, but the cost is high and the control is complicated; some scholars have proposed using PFM ( Pulse frequency modulation) modulation or PWM (pulse width modulation) modulation method combined with phase shift control method, but it is easy to cause the loss of phase shift angle in multi-phase parallel circuit

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