Phase shift and frequency modulation mixed control circuit for LLC resonant power supply

Abstract

The invention discloses a phase shift and frequency modulation mixed control circuit for an LLC resonant power supply. The phase shift and frequency modulation mixed control circuit for the LLC resonant power supply comprises an LLC resonant converter and a phase-shift full-bridge resonant control switch tube, wherein the LLC resonant converter consists of an inductor Lr, a capacitor Cr and a voltage transformer T1. The phase shift and frequency modulation mixed control circuit for the LLC resonant power supply is characterized by further comprising an acquisition circuit, a return PID regulating circuit, a proportional amplification frequency regulating circuit, a soft switching frequency range control circuit and a phase-shift full-bridge master control circuit; adjustment reference voltage (ADJ1) and a voltage or current value (back) of an output circuit of the voltage transformer T1 acquired by the acquisition circuit are inputted into the input ends of the return PID regulating circuit respectively, and the return PID regulating circuit outputs control voltage Vc to the phase-shift full-bridge master control circuit; control voltage Vc and frequency-modulation and width-modulation reference voltage (ADJ2) are inputted into the proportional amplification frequency regulating circuit, and the output end of the proportional amplification frequency regulating circuit is connected with the phase-shift full-bridge master control circuit; soft switching control signals are inputted into the input end of the soft switching frequency range control circuit, and the output end of the soft switching frequency range control circuit outputs frequency range control signals to the phase-shift full-bridge master control circuit.

Description

technical field [0001] The invention relates to the field of resonant switching power supply control, in particular to a phase shifting frequency modulation hybrid control circuit for LLC resonant power supply. Background technique [0002] With the continuous update and rapid development of switching power supply technology, as well as the miniaturization, high-frequency and high-reliability of high-power semiconductors, high-frequency switching power supplies have penetrated into all walks of life, and series resonant switching power supplies are also Resonant zero-crossing characteristics, switch operation and zero-crossing soft off state, and because of its good constant current characteristics, it is widely used in charging power supplies, but because its operating current is in a discontinuous mode, relatively large switches are required Due to tube current stress, it is difficult to be suitable for DC power supplies with large output currents. Therefore, new LLC reson...

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Problems solved by technology

[0002] With the continuous update and rapid development of switching power supply technology, as well as the miniaturization, high-frequency and high-reliability of high-power semiconductors, high-frequency switching power supplies have penetrated into all walks of life, and series resonant switching power supplies are also Resonant zero-crossing characteristics, switch operation and zero-crossing soft off state, and because of its good constant current characteristics, it is widely used in charging power supplies, but because its operating current is in a discontinuous mode, relatively large switches are required Due to tube current stress, it is difficult to be suitable for DC power supplies with large output currents. Therefore, new LLC resonant converters are more and more widely used. Especially in the current era of advocating high efficiency and energy saving, LLC resonant power supplies will be the first choice for green power supplies. development trend

[0003] However, pure frequency conversion LLC resonance requires high stability of the DC input power supply, and for a wide range of load variation and wide input voltage variation, the resonant inductor and power transformer will be difficult to design

In medium and high power applications, fixed-frequency phase-shifted full-bridge converters are widely used because of their low voltage stress on switching tubes and easy implementation of ZVS Zero Voltage Switching (ZVS Zero Voltage Switching). However, their disadvantages are: input voltage When the change range is wide, the output filter inductance is large; the secondary rectifier diode is not soft switching, the converter duty cycle has a wide range of change, and the converter efficiency is low at high voltage input; it is difficult to achieve soft switching at light load, that is, light load When the switching loss is large, the noise is large, and the electromagnetic interference is obvious

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