Secondary-Side Power Regulation in Switched Mode Power Supplies
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Solution Overview
Problem
Conventional power supply systems face accuracy issues in power regulation due to distortion of feedback signals from the secondary-side to the primary-side, leading to reduced precision in transformer power-regulation.
Innovation Solution
Implementing secondary-side control-loop processing to generate a switching indication signal, which is communicated through an isolating signal path to the primary-side controller, allowing for more precise regulation of the power applied to the primary winding of the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback signal is transmitted from secondary-side to primary-side for power regulation, then power regulation capability is achieved, but signal distortion occurs reducing measurement precision
Solution Approach 1:
An isolating signal path (such as optocoupler or transformer) is introduced as an intermediary between the secondary-side feedback circuit and the primary-side controller. This mediator transfers the feedback signal while providing galvanic isolation, preventing distortion and ground loop issues, thereby maintaining measurement precision without information loss.
Solution Approach 2:
The power supply system is divided into electrically isolated segments: the secondary-side control circuit and the primary-side controller are separated by an isolating barrier. This segmentation allows independent optimization of each side while maintaining accurate communication through the isolation boundary, preserving signal integrity.
2Loss of energy
If primary-side controller regulates power based on secondary-side feedback, then power conversion efficiency is improved, but control precision is reduced due to feedback distortion
Solution Approach 1:
The isolating signal path acts as a high-fidelity intermediary that preserves the accuracy of control signals while enabling efficient primary-side regulation. By eliminating distortion in the feedback loop, the system achieves both high energy efficiency and precise control.
Solution Approach 2:
A refined feedback mechanism is implemented where the secondary-side controller measures output parameters and transmits accurate feedback through the isolating signal path to the primary-side controller. This enables precise closed-loop control that optimizes power conversion efficiency without sacrificing control precision.
3Measurement precision
If secondary-side control-loop processing is implemented, then signal distortion is reduced, but device complexity increases
Solution Approach 1:
By introducing the isolating signal path as a mediator, the system achieves secondary-side control capability without requiring complex bidirectional communication circuits. The intermediary handles the complexity of isolation, simplifying the overall controller architecture while maintaining high precision.
Solution Approach 2:
The secondary-side controller independently performs control-loop processing and generates switching indications, which are then transmitted through the isolating signal path. This self-service approach at the secondary side eliminates the need for complex primary-side processing of distorted signals, reducing overall system complexity.
Data Source
AI summary
It is possible to achieve more precise power regulation in switched mode power supply systems by performing at least some control-loop processing on the secondary-side of the transformer. In particular, a secondary-side measurement is processed at least partially by a secondary-side controller to obtain a switching indication signal. The switching indication signal is then communicated from the secondary-side controller to a primary-side controller, where it is used to regulate the amount of energy applied to the primary winding. The switching indication signal may be any control signaling instruction that prompts the primary-side controller to regulate and/or modify the power applied to the primary winding. The switching indication signal may be communicated over an isolating signal path, such as a single-ended capacitive coupler, a differential capacitive coupler, an inductive coupler, or an opto-coupler.