Primary inductance correction circuit applied to flyback switching power supply

Abstract

The invention discloses a primary inductance correction circuit applied to a flyback switching power supply. The primary inductance correction circuit mainly solves the problem that the primary magnetic inductance of a conventional transformer is deviated to influence output power. The primary inductance correction circuit comprises a clamper, a sampling control and current-voltage converter, a voltage stabilizer / isolator, a voltage-current converter, an equilibrium point controller and an oscillator. In the power tube conduction time of the flyback switching power supply, the sampling and current-voltage converter samples current flowing out of a control end, performs I-V conversion, voltage stabilization / isolation and V-I conversion on discontinuously sampled current, and outputs offset current. The clamper clamps the voltage at the control end to zero. The equilibrium point controller makes the offset current be zero when a primary magnetic inductance value is normal. The offset current is injected into the oscillator to change the frequency of the oscillator and further change switching frequency to correct an output power change caused by inductance tolerance. The primary inductance correction circuit has a simple structure, low power consumption and stable and accurate offset current.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and relates to an analog integrated circuit, in particular to a primary inductance correction circuit, which can be used in a flyback switching power supply transformer in the design of a switching power supply. Background technique [0002] In the field of switching power supplies, flyback converters are especially suitable for low-power switching power supplies and various power adapters due to their simplicity, high efficiency, and low cost. However, there are many difficulties in the design process of flyback converters. Among them, due to the influence of the manufacturing process and design defects, the primary excitation inductance will have a certain range of deviation from the ideal value, which will greatly reduce the performance of the entire switching power supply and affect the working state of the chip. [0003] figure 1 It is a typical flyback switching power supply ci...

AI Technical Summary

Problems solved by technology

Due to the lack of corresponding correction and compensation functions in traditional integrated circuits, the influence of the deviation generated by the primary inductance on the output power cannot be avoided, resulting in a decrease in the accuracy of system design and limiting the development of integrated circuits

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