Current reference generation circuit, constant current switch power supply control circuit and control method thereof

Abstract

The invention provides a current reference generation circuit which comprises the following parts: a first multiplier module which receives a rectification voltage waveform signal of a switch power supply and an output signal of an average electric current loop, and generates a sine half-wave signal which has same frequency and phase with the rectification voltage waveform signal and changes with the output signal of the average electric current loop; a second multiplier module which inputs the sine half-wave signal and a control signal and generates a pulse signal; the average electric current loop which compares an average value of the pulse signal with a set average electric current loop reference signal. The current reference generation circuit can generate a reference signal followed by a primary current signal of a self-adapting switch power supply main circuit and provides the reference signal to a high power factor constant current switch power supply control circuit, and the reference signal carries out self-adapting adjustment with circuit input output condition change so as to satisfy a requirement of secondary constant current output. Simultaneously, based on the current reference generation circuit, the invention realizes a primary controlled high power factor constant current switch power supply control circuit and a control method thereof.

Description

technical field [0001] The invention belongs to the technical field of switching power supplies, and relates to a high power factor constant current switching power supply primary side current reference generation circuit, control circuit and method for adaptive primary side control. Background technique [0002] At present, many isolated power supplies such as mobile phone chargers and high-power LED drivers usually require the circuit to have the function of outputting constant current due to application requirements; IEC1000-3-2, etc., the above isolated power supply must also have power factor correction (PFC) function, figure 1 It is a commonly used single-stage power factor correction scheme at present: by detecting the output current on the secondary side of the transformer, after the secondary side is controlled by constant current, it is fed back to the primary side PFC control circuit through the optocoupler. figure 1 In the prior art solution shown, due to the ex...

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Problems solved by technology

However, in the presence of a phase-controlled dimmer, the AC input signal will be missing when the dimming angle is different, and its rectification is no longer a complete half-wave, so the input feedforward signal Vff contains the phase-cut angle signal, The voltage feed-forward control will cause Iref to increase sharply with the increase of the phase-cut angle, and the input power will also increase sharply, so the above method is not suitable for the occasion of phase-controlled dimming

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