Power Supply Circuit Secondary-to-Primary Communication
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Solution Overview
Problem
Primary-side regulation in power supplies with flyback converter topology faces challenges in detecting output voltage drops during low load or standby conditions, leading to output voltage undershoot due to infrequent sampling of the sense voltage.
Innovation Solution
Implementing secondary side to primary side communication through a dynamic detection signal induced by the secondary-side controller IC, which controls the switching of the secondary-side switch to generate a resonant signal on the primary winding, allowing the primary-side controller IC to sense this signal and maintain output voltage stability by turning on the primary-side switch during standby or low load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If primary-side regulation is used to control output voltage by sensing on the primary side, then sensing losses are removed and device complexity is reduced, but output voltage detection precision deteriorates during low load conditions leading to voltage undershoot
Solution Approach 1:
The patent introduces an intermediary mechanism (secondary-side switch controlled by secondary-side controller) that generates detection signals to mediate between the primary-side controller and the actual output voltage condition. This intermediary allows the primary-side controller to indirectly detect output voltage status without direct sensing, resolving the contradiction between simplified control and accurate detection.
Solution Approach 2:
The patent implements a feedback mechanism where the secondary-side controller monitors output voltage and provides information back to the primary-side controller through controlled switching actions. This feedback loop enables the primary-side controller to adjust its operation based on actual output conditions, maintaining detection precision while using simplified primary-side sensing.
2Use of energy by moving object
If sampling frequency is reduced during standby mode to save energy, then energy consumption is reduced, but output voltage regulation stability deteriorates due to infrequent sampling
Solution Approach 1:
The patent applies dynamic sampling strategy where the sampling frequency is adjusted based on operating conditions. During standby mode with stable load, sampling frequency is reduced to save energy. When load changes are detected (through the intermediary detection mechanism), sampling frequency increases dynamically to maintain voltage stability, thus resolving the contradiction between energy saving and stability.
Solution Approach 2:
The patent uses preliminary detection actions by the secondary-side controller that can trigger increased sampling before significant voltage deviations occur. This preliminary action allows the system to prepare for potential voltage instability by increasing sampling frequency proactively, maintaining stability while minimizing unnecessary high-frequency sampling during stable conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution prevents significant output voltage undershoot by enabling more frequent sampling of the sense voltage, ensuring stable output voltage regulation even during low load conditions.
Implementation Method 1
a dynamic detection signal may be induced by a secondary-side controller IC by controlling switching of a switch that is coupled to a secondary winding of the transformer
Data Source
AI summary
An electrical circuit for a power supply includes a primary-side controller integrated circuit (IC) that outputs a drive signal on a switch pin to control a switching operation of a switch that is coupled to a primary winding of a transformer. The primary-side controller IC places the switch pin at high impedance during a sense window and turns on the switch in response to sensing a dynamic detection signal on the switch pin during the sense window. The dynamic detection signal is induced by a secondary-side controller IC by controlling switching of a switch that is coupled to a secondary winding of the transformer when the output voltage drops below a predetermined threshold during standby or other low load conditions.