Primary side constant current control device of LLC resonant converter

Abstract

The invention discloses a primary side constant current control device of an LLC resonant converter, which comprises an equivalent output current module, an adjusting ring module and an LLC drive control module connected in sequence, wherein the equivalent output current module comprises a comparison module, a winding voltage rectification module, an intermittent time detection module, a samplingcurrent rectification module and a current conditioning module. A signal reflecting the turn-off time of a secondary rectifier tube of the LLC resonant converter and a primary side current signal obtained by sampling after offsetting a transformer exciting current component of the LLC resonant converter are received, and an output current equivalent signal vIo_est reflecting the equivalent averageoutput current is outputted. By adding the intermittent interval sampling current signal shielding circuit in the primary side constant current controller, the influence of the element tolerance of the LLC resonant converter main circuit on the output constant current precision can be effectively improved.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and relates to a primary side constant current control device of an LLC resonant converter. Background technique [0002] With the continuous updating of products such as mobile consumer electronic equipment and lighting equipment, the power requirements of various equipment for power converters are getting higher and higher. However, due to the low utilization rate of the flyback transformer, the flyback converter cannot meet the efficiency requirements under the condition of higher output power, and its application is generally only applicable below 80W. For higher power requirements, the LLC resonant converter with pulse frequency modulation is widely used in various power electronic devices due to its advantages of low loss and high power density. However, while obtaining high efficiency and high power density, the increased system volume and cost do not meet the application...

AI Technical Summary

Problems solved by technology

However, limited by the manufacturing process, the auxiliary resistor, auxiliary capacitor and transformer excitation inductance also have component tolerances, which will deteriorate the output constant current accuracy.

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