LLC resonant converter with wide load range

Abstract

The invention discloses an LLC resonant converter with a wide load range. Load current of the LLC resonant converter directly flows through a secondary winding of a variable inductor, so that a resonance inductance value in a resonant network is controlled to be changed with the change of output current, such as, the variable resonance inductance value is the minimum when the output current is the maximum, and the ratio between an excitation inductance value of a transformer is the minimum, thus a high full load efficiency can be obtained; while with the decrease of the output current, the variable resonance inductance value increases, and the ratio between the excitation inductance value of the transformer increases, thus the load output range is widened; and on the premise of obtaining constant current characteristics of wide range load current, the LLC resonant converter with provided by the invention can obtain a relatively high efficiency, and meanwhile, the LLC resonant converter and a control circuit are of a simple structure, and a complicated driving device and a drive and control circuit are not needed, thereby reaching the purpose of reducing the circuit cost and improving the efficiency and stability of a driver.

Description

technical field [0001] The invention belongs to the field of DC / DC converters and LED lighting, and in particular relates to an LLC resonant conversion device with a wide load range. Background technique [0002] After the 21st century, LED has been rapidly promoted and applied as a new generation of green lighting. With the development of new technologies, further improving lighting efficiency and improving the lighting environment, LED lighting with higher power and dimming output has gradually become a new development trend. LLC resonant converter, because of its own working characteristics, can achieve high efficiency, high power density and high stability, so it can be widely concerned and applied. [0003] figure 1 Shown is a simplified schematic diagram of a prior art LLC resonant converter used in an LED driver, and the LED driver includes an LLC resonant converter main circuit and an LLC drive control circuit. Among them, the main circuit of the LLC resonant conv...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the present invention is to provide a new type of LLC resonant conversion device to overcome the problem that the traditional LLC resonant converter is easy to enter the hiccup mode when the light load frequency is too high when it is applied to a wide load range, and other solutions or complicated control or high circuit cost

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