Half-Bridge Flyback Converter Resonance Capacitor Discharge
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Solution Overview
Problem
The asymmetric half-bridge flyback converter experiences a surge current when power is re-supplied after an AC power source stops and then restarts, potentially damaging switches and increasing stress and cost.
Innovation Solution
A power converter with an inductance-capacitance resonance circuit and a discharging circuit connected in parallel to the resonance capacitor, which releases accumulated energy when power is stopped, ensuring zero voltage across the capacitor when power is re-supplied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the asymmetric half-bridge flyback converter uses the LLC resonance circuit structure to achieve primary-side zero-voltage switching and wide voltage output, then the power conversion efficiency and voltage range are improved, but the resonance capacitor retains accumulated energy after AC power source stops supplying power, causing surge current when power is re-supplied which increases the risk of damage to switches and requires increased stress level of switches, thereby increasing cost
Solution Approach 1:
The controller activates the discharging circuit before the AC power source re-supplies power to release accumulated energy from the resonance capacitor. This preliminary action ensures the capacitor voltage is reduced to a safe level before normal operation resumes, preventing surge current and protecting the switches from damage while maintaining the high efficiency benefits of the resonance circuit
Solution Approach 2:
The discharging circuit acts as an intermediary component between the resonance capacitor and the rest of the converter circuit. It provides a controlled path for releasing accumulated energy, mediating the harmful effect of capacitor voltage on switch reliability without affecting the primary power conversion function of the resonance circuit
2Adaptability or versatility
If the asymmetric half-bridge flyback converter uses the LLC resonance circuit structure to achieve primary-side zero-voltage switching and wide voltage output, then the power conversion efficiency and voltage range are improved, but the resonance capacitor retains accumulated energy after AC power source stops supplying power, causing surge current when power is re-supplied which requires increased stress level of switches, thereby increasing cost
Solution Approach 1:
The controller activates the discharging circuit before the AC power source re-supplies power to release accumulated energy from the resonance capacitor. This preliminary action ensures the capacitor voltage is reduced to a safe level before normal operation resumes, preventing surge current and protecting the switches from damage while maintaining the high efficiency benefits of the resonance circuit
Solution Approach 2:
The discharging circuit uses simple, low-cost components (resistor and switch) that are temporarily activated only when needed to release accumulated energy. This disposable-like approach to energy management provides protection against surge current without requiring expensive, high-stress-rated switches, thereby reducing overall circuit cost while maintaining wide voltage output capability
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
The solution prevents surge currents by ensuring the resonance capacitor is at zero voltage when power is re-supplied, protecting switch components and reducing stress and cost.
Implementation Method 1
the resonance inductor and the resonance capacitor execute a resonance operation so as to transfer the energy stored in the resonance inductor to the secondary-side winding
Implementation Method 2
the energy accumulated in the resonance capacitor is released through a discharging path provided by the resistor and the switch
Data Source
AI summary
A power converter includes a transformer, an inductance-capacitance resonance circuit, a first switch, a second switch, and a controller. The transformer includes a primary-side winding and a secondary-side winding. The inductance-capacitance resonance circuit is coupled to the primary-side winding, and the inductance-capacitance resonance circuit includes a resonance capacitor and a resonance inductor. The first switch and the second switch are coupled to the inductance-capacitance resonance circuit. The controller receives an output voltage feedback signal of the power converter and complementarily controls the first switch and the second switch to be turned on and turned off according to the output voltage feedback signal so as to adjust an output voltage of the power converter.