Flyback Secondary Buffer Circuit for Leakage Spike Reduction
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Solution Overview
Problem
Existing switching power supplies face inefficiencies and increased costs due to spike voltages generated by secondary leakage inductors, which can be mitigated but at the expense of either using high-voltage diodes or RC buffer circuits that compromise efficiency and add complexity.
Innovation Solution
A buffer circuit incorporating a capacitive element that resonates with the secondary leakage inductor, allowing discharge currents to bypass resistive elements, thereby reducing energy storage in the primary leakage inductor and enhancing efficiency without heat loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an RC buffer circuit is used to mitigate spike voltages, then voltage protection is improved, but efficiency deteriorates due to resistive losses
Solution Approach 1:
The patent extracts the resistive element from the buffer circuit, using only a capacitive element to mitigate spike voltages. The capacitor absorbs the voltage spike energy without dissipating it as heat, thereby maintaining efficiency while providing voltage protection.
Solution Approach 2:
The patent converts the harmful spike voltage energy into beneficial stored energy in the capacitive element. Instead of dissipating the energy harmfully through resistance, the capacitor stores it temporarily and allows it to be recovered or safely discharged, turning a harmful effect into a potentially useful one.
2Reliability
If high-voltage diodes are used to withstand spike voltages, then voltage protection is improved, but cost and device complexity increase
Solution Approach 1:
The patent replaces expensive high-voltage diodes with a simpler, cheaper capacitive element. The capacitor provides the necessary voltage protection function without requiring expensive high-voltage components, reducing both cost and device complexity while maintaining reliability.
3Object-affected harmful factors
If RC buffer circuits are used to reduce spike voltages, then EMI performance is improved, but efficiency deteriorates due to heat loss
Solution Approach 1:
The patent removes the resistive element from the traditional RC buffer circuit, retaining only the capacitive function. This extraction eliminates the source of heat loss while preserving the EMI filtering capability, as the capacitor can still absorb and smooth voltage spikes without dissipating energy as heat.
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 approach effectively reduces spike voltages and improves the electromagnetic interference (EMI) performance and efficiency of switching power supplies by eliminating resistive losses and maintaining high EMI performance.
Implementation Method 1
A buffer circuit incorporating a capacitive element that resonates with the secondary leakage inductor
Data Source
AI summary
A buffer circuit coupled in parallel to a rectifier circuit in a secondary side of a flyback converter, the buffer circuit including: a capacitive element configured to be charged by an output capacitor when a primary power switch in the flyback converter is turned on; and the capacitive element being configured to be discharged through a secondary winding of a transformer when the primary power switch is turned off, in order to reduce energy stored in a primary leakage inductor in a primary side of the flyback converter, whereby a spike voltage generated in a secondary leakage inductor in the secondary side is reduced, and efficiency of the flyback converter is improved.