Magnetic isolation feedback circuit of space power supply

Abstract

The invention relates to a magnetic isolation feedback circuit of a space power supply. The magnetic isolation feedback circuit comprises a magnetic isolation modulation circuit composed of a secondary side error amplification electric appliance EA, a high-frequency small-signal transformer Tc and a controlled driving current source iC, a demodulator composed of a sampling switch SH and a holdingcapacitor CH, and other functional circuits. The output voltage Vout of the converter and a reference VREF in an error amplifier EA are subjected to error amplification to generate a control signal VEA, and the control signal VEA is subjected to magnetic coupling transmission through a signal transformer TC periodically excited by a driving current source iC controlled by an external driving signal. A primary side control signal V * EA is formed after a sampling switch on the secondary side of a transformer, SH and a sampling/holding circuit composed of a holding capacitor bank CH, then the primary side control signal V * EA is compared with a high-frequency sawtooth wave VRAMP signal in a PWM comparator to generate a pulse width modulation PWM logic level, and PWM is sent to a switching device driving electrode of a main power circuit after the driving capacity of PWM is improved through a gate driving circuit. The duty ratio adjusting circuit is used for adjusting the duty ratio D ofa switching device so as to adjust the output voltage.

Description

technical field [0001] The invention belongs to an isolated feedback control mode realization circuit of a power converter, relates to a space power supply magnetic isolation feedback circuit, and specifically designs a low-cost circuit based on a high-frequency signal transformer and an integrated pulse width modulator (PWM IC) UCX845 , high reliability and excellent performance magnetic isolation feedback circuit has a bright application prospect in the field of space power supply. Background technique [0002] In order to improve the safety and reliability of the spacecraft, the power conversion devices used on it mostly adopt the isolated topology. The isolated power supply is recognized as a difficult point in the field of space power supply design, involving relatively complex electromagnetic field theory issues. "Isolation" includes two aspects: 1) Main power circuit isolation; 2) Feedback control circuit isolation. The main power circuit isolation is mostly achieved...

AI Technical Summary

Problems solved by technology

However, due to the inherent defects of optocouplers: ①Due to the differences in manufacturing processes, there are large differences between the characteristics of the primary side emitting diode and the secondary side photosensitive transistor of different optocoupler devices, resulting in a large tolerance between the characteristics of the finished product. It will increase the workload of stand-alone debugging and testing, and it is difficult to achieve mass production between power converters; ②The complex space radiation environment and wide range of temperature changes will make the key parameter CTR (current transfer ratio) of the optocoupler device Large fluctuations will lead to large-scale fluctuations in the compensation loop gain, which will reduce the gain margin and phase margin of the power supply, and reduce the robustness against input and load fluctuations

The disadvantage of the former is that the CTR (Current Transfer Ratio) parameter of the optocoupler will change greatly with temperature, time, and radiation environment, which will cause large fluctuations in the gain of the feedback control loop, thereby affecting the gain and phase margin of the converter, making the power supply Converter Robustness Degradation

The disadvantage of the latter is that it requires a separate power supply for the secondary side, and usually requires a special "bootstrap circuit"

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