Flyback Converter Circuit Arrangement Without Smoothing Capacitor
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Solution Overview
Problem
Existing LED operation circuits require large and vulnerable smoothing capacitors, increasing costs and reducing service life, despite efficient operation being possible only with a predetermined voltage drop and current range, which existing AC LED modules struggle to achieve efficiently.
Innovation Solution
A circuit arrangement using a transformer with a controllable switching element and an RC element to adjust the steepness of the rising or falling edge of the control signal for the switch, allowing efficient LED operation without a smoothing capacitor, by utilizing a rectified AC voltage and monitoring the secondary-side current for optimized control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smoothing capacitor is used in the flyback converter circuit, then the LED operation is stable with predetermined voltage and current, but the circuit complexity and cost increase and the service life decreases
Solution Approach 1:
The patent removes the smoothing capacitor from the flyback converter circuit, extracting the problematic component that caused reliability and complexity issues. The circuit operates directly with rectified AC voltage without requiring capacitor-based smoothing, thereby eliminating the vulnerability and cost associated with large-capacity capacitors while maintaining stable LED operation through alternative control mechanisms.
Solution Approach 2:
The patent changes the operating parameters of the flyback converter by eliminating the capacitor-dependent smoothing approach. Instead, it uses direct control of the switching element based on the rectified AC voltage characteristics, transforming the circuit from a capacitor-based voltage stabilization system to a control-based current regulation system, thereby improving reliability and reducing complexity.
2Reliability
If a large smoothing capacitor is used to stabilize voltage, then LED operation is reliable, but the cost and vulnerability of the circuit increase
Solution Approach 1:
The patent extracts and removes the large smoothing capacitor from the circuit, eliminating the need for expensive, high-capacity capacitor components. The circuit achieves stable LED operation through direct control of the switching element based on rectified AC voltage, replacing the capacitor-based solution with a control-based approach that reduces manufacturing cost and component vulnerability.
Solution Approach 2:
The patent replaces the expensive, vulnerable smoothing capacitor with a more economical circuit configuration that uses standard rectified AC voltage and control electronics. By eliminating the need for large-capacity, high-reliability capacitors, the patent adopts a more cost-effective approach using readily available components with standard specifications.
3Device complexity
If rectified AC voltage is used without smoothing, then the circuit is simpler and more reliable, but additional control measures are required to achieve desired current flow
Solution Approach 1:
The patent implements feedback control by monitoring the current in the primary winding and using this information to control the switching element. The control unit adjusts the switching duty cycle based on the detected current level, creating a closed-loop system that automatically regulates the current through the LED string without requiring complex external control circuitry or large smoothing capacitors.
Solution Approach 2:
The circuit uses the rectified AC voltage directly without external smoothing, allowing the system to self-regulate through the inherent characteristics of the rectified voltage waveform. The control unit leverages the natural voltage variations to achieve current regulation, making the circuit simpler and more self-sufficient while maintaining reliable LED operation.
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
Enables efficient and precise control of the switch to achieve desired current flow on the secondary side, reducing the need for a primary-side smoothing capacitor and improving the reliability and cost-effectiveness of LED operation.
Implementation Method 1
a transformer for transmitting electrical energy from a primary winding to a secondary winding
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a circuit arrangement (1) for operating lamps (110), comprising a circuit that can be supplied with a voltage and pulsed by means of at least one switch (11), by which means a transformer (10) is powered, the lamps (110) being supplied with current by means of a secondary winding (L2) of the transformer (10). The supply voltage (UDC) for the transformer (10) is a rectified, non-smoothed alternating voltage, a control unit (20) being designed to adapt to at least one of the following parameters for controlling the switch (11), according to the supply voltage (UDC) for the transformer (10): the switching frequency; the pulse duty factor; and the steepness of the rising or falling edge.