Active Clamp Flyback Converter for Compact Power Supply Design
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Solution Overview
Problem
Conventional switching power supply circuits face challenges in downsizing due to the presence of a voltage doubler half-wave rectifying circuit on the secondary side of the insulated converter transformer, which hinders further miniaturization of power supply devices used in electronic apparatuses.
Innovation Solution
A power supply device incorporating an active clamp type flyback converter with a main switching element, a sub switching element, a flyback transformer, and a rectifying element, where the control unit alternates between different control modes to generate a resonance phenomenon, reducing the capacitance and inductance requirements and allowing for downsizing of the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a voltage doubler half-wave rectifying circuit is used on the secondary side of the insulated converter transformer, then the power supply circuit can achieve proper voltage rectification, but the circuit size cannot be further reduced
Solution Approach 1:
The patent extracts the voltage doubling function from the traditional voltage doubler half-wave rectifying circuit and relocates it to the primary side through the active clamp circuit. This separation allows the secondary side to use a simpler half-wave rectifying circuit with fewer components, thereby reducing the overall power supply device size while maintaining the voltage doubling capability.
Solution Approach 2:
The active clamp circuit on the primary side serves multiple functions: it acts as both a voltage doubling mechanism and a clamp circuit for voltage regulation. This multi-functionality eliminates the need for a separate voltage doubler circuit on the secondary side, reducing component count and device size.
2Volume of moving object
If the transformer winding number is reduced for downsizing, then the power supply device becomes more compact, but the resonance phenomenon must be precisely controlled
Solution Approach 1:
The patent employs a control unit that monitors the resonance phenomenon and adjusts the switching timing of the main and sub switching elements accordingly. This feedback mechanism ensures that even with reduced transformer winding numbers, the resonance occurs at the correct phase and amplitude, maintaining stable operation despite the compact transformer design.
Solution Approach 2:
The patent makes the switching frequencies of the main switching element and sub switching element dynamically adjustable based on the resonance conditions. By optimizing the switching timing in real-time, the system maintains precise resonance control with the reduced transformer winding number, achieving both compact size and stable performance.
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 enables the reduction of the transformer's winding number, leading to a more compact power supply device design while maintaining efficient operation and suppressing flickering of the light source unit.
Implementation Method 1
a waveform, with respect to time in the period, of a second voltage that is generated between the first main terminal and the second main terminal of the main switching element takes a protruding curve shape, the voltage being generated due to a resonance phenomenon of at least the resonance capacitor, the primary winding, and the resonance inductor
Data Source
AI summary
In a power supply device, a primary winding of a transformer is connected in series to a main switching element, and is connected in parallel to a series circuit of a resonance capacitor and a sub switching element. A secondary winding of the transformer is connected in series to a series circuit of a rectifying element and a resonance inductor. The capacitance of the resonance capacitor and the inductance of the resonance inductor are each set such that, when the sub switching element is in an on state, the waveform of the voltage that is generated between the first main terminal and the second main terminal of the main switching element takes a protruding curve shape, the voltage being generated due to a resonance phenomenon of at least the resonance capacitor and the resonance inductor.