Full-Bridge Power Source Logic Control for Transformer Biasing
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Solution Overview
Problem
Existing power source controllers face challenges in balancing input disturbance suppression and output disturbance suppression, particularly in isolated power sources, where input voltage detection is difficult, leading to transformer biasing and reduced feedforward sensitivity.
Innovation Solution
A power source management method that adjusts control signals of switching transistors in a full-bridge topology circuit using a logic control circuit, based on sampled secondary-side voltage, to ensure symmetric operating duty cycles and prevent transformer biasing, while maintaining good feedforward performance and quick response to input voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If controller is placed on secondary side for isolated power source, then communication ease is improved, but input voltage detection becomes difficult
Solution Approach 1:
The patent uses the secondary-side output voltage as an intermediary to infer primary-side input voltage conditions. By detecting the output voltage waveform and using it to generate the reference current, the system indirectly obtains input voltage information without requiring direct primary-side sensing, thus maintaining ease of communication while enabling input voltage detection.
Solution Approach 2:
The patent replaces direct electrical sensing of input voltage with an indirect method using output voltage waveform analysis. Instead of mechanically or electrically connecting sensors to the primary side, the system uses the available secondary-side voltage signals to derive the necessary control information.
2Device complexity
If digital feedforward sampling point is used, then feedforward control is simplified, but feedforward sensitivity is reduced
Solution Approach 1:
The reference current waveform is generated in advance by the voltage loop before the current loop execution. This preliminary generation of the reference signal allows the current loop to simply track it, simplifying the digital implementation while maintaining high sensitivity because the reference is continuously updated based on real-time voltage conditions.
Data Source
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AI summary
A power source management method and a power source are provided. The method includes: comparing a feedforward control signal with a feedback control signal by using a logic control circuit, outputting the signals after the comparison, and performing matching, to obtain control signals of switching transistors of a full-bridge topology circuit (S301); and adjusting the control signals of the switching transistors of the full-bridge topology circuit by using the logic control circuit, so that operating duty cycles of two bridge arms on a primary side match, are symmetric within one switch period of the logic control circuit, or match for a long time, to prevent transformer biasing (S302). The power source management method and the power source can achieve good feedforward performance, suppress input disturbance, and additionally prevent transformer biasing, which ensures that the power source works normally.