Switching Power Supply Auto-Supply Voltage Stabilization Circuit
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Solution Overview
Problem
Switching power supplies face challenges in stabilizing auto-supply voltage, particularly at varying loads, leading to intermittent operation and inefficiencies due to parasitic transformer parameters and high voltage peaks, which existing solutions fail to adequately address without compromising efficiency or compliance with energy regulations.
Innovation Solution
A circuit with a controlled switch that selectively connects the transformer secondary to the control circuit after a predefined delay from the deactivation command, using a driving circuit to manage the switch's closing signal, thereby minimizing auto-supply voltage variations and ensuring stable operation across different load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transformer secondary is continuously connected to the control circuit, then the auto-supply voltage is maintained, but voltage peaks and parasitic parameters cause instability and intermittent operation
Solution Approach 1:
The controlled switch is activated in advance before the deactivation command is issued, creating a time delay that prevents the control circuit from being connected during high-voltage peaks. This preliminary action filters out harmful voltage transients while maintaining stable auto-supply voltage for the control circuit.
2Speed
If the controlled switch is activated immediately upon deactivation command, then the response time is minimized, but auto-supply voltage drops below the stop threshold causing intermittent operation
Solution Approach 1:
The controlled switch is activated before the deactivation command is fully processed, introducing a predetermined time delay. This ensures the switch remains closed long enough to maintain auto-supply voltage above the stop threshold, preventing intermittent operation while still providing timely response to load changes.
3Reliability
If the switch remains closed longer during deactivation, then auto-supply voltage stability is improved, but power dissipation and energy loss increase
Solution Approach 1:
The switch activation timing is dynamically adjusted based on the deactivation command state. The controlled switch is activated only during the brief period when the deactivation command is issued, maintaining voltage stability precisely when needed while minimizing unnecessary extended closure that would increase power dissipation and energy loss.
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 effectively stabilizes the auto-supply voltage, ensuring safe operation during short circuits, reducing overload risks, and improving efficiency while maintaining compliance with energy regulations by extending the stable voltage interval and reducing power dissipation.
Implementation Method 1
A circuit for reducing the variations of auto-supply voltage of a control circuit of a switching power supply... comprises a generator of said auto-supply voltage... a transformer and a switch (typically MOSFET) that periodically connects a transformer winding to the input source
Implementation Method 2
a driving circuit of said controlled switch that supplies a closing signal of said controlled switch after a predefined time delay starting from said deactivation command
Data Source
AI summary
A circuit for reducing the variations of auto-supply voltage of a control circuit of a switching power supply, where the control circuit supplies an activation or deactivation signal of a power transistor, includes an auto-supply voltage generator, a controlled switch capable of selectively connecting the generator to the control circuit, and a driving circuit of the controlled switch that supplies a closing signal of the controlled switch after a predefined delay of time starting from the deactivation command.