Control circuit and method for compensating output loss of power converter

Abstract

The invention discloses a control circuit and method for compensating the output loss of a power converter. The control circuit includes a sampling voltage generator, a time-to-voltage converter and a compensation signal generator. The sampling voltage generator generates a sampling voltage corresponding to the detection voltage according to a first reference current, a second reference current and a detection voltage. The time-to-voltage converter generates a corresponding voltage according to the period of the gate control signal controlling the power switch of the primary side of the power converter and the discharge time of the secondary side of the power converter. The compensation signal generator generates a compensation signal for compensating the output loss according to the sampling voltage and the corresponding voltage. Therefore, compared with the prior art, because the compensation signal can make a compensation voltage change linearly and positively with the load coupled to the secondary side of the power converter, the present invention can improve the voltage stabilization effect of the prior art Bad downside.

Description

technical field [0001] The present invention relates to a control circuit and method for compensating the output loss of a power converter, in particular to a method capable of generating a compensation signal so that the compensation voltage changes linearly and positively with the load coupled to the secondary side of the power converter control circuit and its method. Background technique [0002] In the prior art, the control circuit applied to the primary side of the power converter can utilize the compensation voltage VCOMP corresponding to the voltage of the auxiliary winding of the power converter and the output voltage corresponding to the secondary side of the power converter , to stabilize the output voltage of the secondary side of the power converter, and compensate the output loss of the secondary side of the power converter. However, because the prior art also uses the compensation voltage VCOMP to determine the frequency reduction curve L corresponding to th...

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Problems solved by technology

However, because the prior art also uses the compensation voltage VCOMP to determine the frequency reduction curve L corresponding to the gate control signal (such as figure 1 shown, and the gate control signal is used to control the power switch on the primary side of the power converter to turn on and off), and the compensation voltage VCOMP is in the frequency conversion intervals A and B of the frequency reduction curve L (such as figure 1 shown) does not change linearly and positively with the load coupled to the secondary side of the power converter, so the compensation corresponding to the output loss will also have nonlinear characteristics, resulting in the corresponding The error of the output voltage on the secondary side becomes larger

Therefore, the voltage stabilizing effect of the prior art is not good

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