Flyback Converter Primary-Side Current Control
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Solution Overview
Problem
Existing power supplies for controlling current require additional components like opto-couplers and comparators due to electrical insulation through transformers, leading to increased costs and spatial limitations, especially when controlling current for loads like incandescent lamps.
Innovation Solution
A power supply system that includes a rectifier, transformer, sampler, integrator, switching controller, and level detector to directly control current flowing through a load line unit by sampling peak current values and integrating signals proportional to the peak values, allowing for efficient feedback control without the need for additional components like opto-couplers and comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opto-coupler and comparator are used for feedback control through transformer insulation, then electrical insulation is maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the opto-coupler and comparator components from the feedback control system. By using primary-side sensing that directly monitors the current through the transformer primary winding and implements control without secondary-side feedback components, the system maintains electrical insulation while removing the complex opto-coupler and comparator circuitry.
Solution Approach 2:
The patent makes the transformer serve multiple functions: it provides both electrical insulation between primary and secondary sides and enables direct current sensing through its primary winding. The same transformer structure that provides isolation also serves as the sensing element, eliminating the need for separate opto-coupler and comparator components.
2Ease of operation
If opto-coupler and comparator are used for feedback control, then current control is achieved, but spatial requirements increase
Solution Approach 1:
The patent removes the opto-coupler and comparator components that occupy physical space in the circuit. By implementing primary-side current sensing and control, the system achieves current control functionality with fewer discrete components, thereby reducing the overall spatial requirements of the power supply circuit.
3Reliability
If additional components are used for feedback control, then insulation is maintained, but production cost increases
Solution Approach 1:
The patent extracts and eliminates the expensive opto-coupler and comparator components from the circuit. By using primary-side sensing that leverages the transformer's inherent properties, the system maintains electrical insulation while significantly reducing component count and production cost.
Solution Approach 2:
The patent replaces expensive opto-coupler and comparator components with simpler, cheaper sensing circuitry that uses the transformer primary winding as the sensing element. This substitution with lower-cost components reduces production expenses while maintaining the required insulation functionality.
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 reduces production costs and spatial requirements by enabling direct feedback control of current through the transformer, improving efficiency and accuracy in controlling current for various loads, including light emitting devices, while maintaining power factor correction.
Implementation Method 1
a transformer which receives the first current and converts it into a second current and supplies the second current to a load line unit
Implementation Method 2
a rectifier which rectifies an input AC voltage into a direct current (DC) voltage
Data Source
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AI summary
The present invention relates to a power supply for controlling current. The power supply for controlling current according to the embodiment of the present invention uses a flyback converter for the sake of electrical insulation between a load line unit and the power supply for controlling current. In a transformer (a flyback converter) having a flyback structure in the present invention, disclosed is a device which expects a current of the second coil by sensing a current of the first coil of the transformer,, and controls the current flowing through the load line unit. A level detector is included, which updates a duty time or an on-time of the switch (SW) by transferring a reset signal to an integrator and a second sampler in accordance with a cycle of an input power. As a result, it is possible to reduce power loss by increasing a power factor through the adjustment of the phase of the current of the load line unit and an input voltage.