Dual-Secondary Flyback Converter for EMI Noise Cancellation
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Solution Overview
Problem
Current flyback converters used in low-power isolated lighting device drivers generate significant electromagnetic interference (EMI), necessitating costly complex filter circuits for suppression.
Innovation Solution
A flyback converter design that includes a transformer with a primary winding and two secondary windings, connected in a configuration that creates two noise signal propagation paths in opposite directions, effectively canceling noise signals and suppressing EMI without complex filter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex filter circuits are used to suppress EMI, then electromagnetic interference is reduced, but device complexity and cost increase
Solution Approach 1:
The patent applies the principle of converting harmful EMI noise into beneficial signal cancellation by using two secondary windings with opposite polarity connections. The noise signals generated in both secondary windings are intentionally designed to be equal in magnitude but opposite in polarity, causing them to cancel each other out. This transforms the harmful EMI effect into a beneficial noise cancellation mechanism, eliminating the need for complex external filter circuits.
Solution Approach 2:
The patent employs asymmetric connection configurations where the first and second secondary windings are connected with opposite polarities. Specifically, the first end of the first secondary winding is connected to the first end of the second secondary winding, while the second end of the first secondary winding is connected to the second end of the second secondary winding through a rectifying element. This asymmetric arrangement creates opposite-phase noise signals that cancel each other, reducing EMI without requiring symmetric complex filtering components.
2Object-affected harmful factors
If complex filter circuits are used to suppress EMI, then electromagnetic interference is reduced, but overall cost increases
Solution Approach 1:
By converting the harmful EMI effect into a beneficial noise cancellation mechanism through opposite-polarity winding connections, the patent eliminates the need for expensive external filter circuits. This approach reduces manufacturing costs while maintaining EMI suppression effectiveness.
Solution Approach 2:
The flyback converter circuit performs its own EMI suppression function through the inherent characteristics of its dual secondary winding configuration. The circuit generates and cancels its own noise signals internally, making it self-sufficient and eliminating the need for additional expensive EMI filter components, thereby reducing overall manufacturing cost.
3Device complexity
If conventional flyback converter design is used, then circuit simplicity is maintained, but electromagnetic interference is significant
Solution Approach 1:
The patent segments the secondary side of the transformer into two separate windings with distinct opposite-polarity connections. This segmentation allows each winding to generate noise signals that can cancel each other out, achieving EMI suppression while maintaining relatively simple circuit design. The segmentation of the transformer windings creates the necessary conditions for noise cancellation without requiring complex external circuitry.
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 design significantly reduces electromagnetic interference, lowers the overall cost of the lighting device, enhances the performance and reliability of the flyback converter, and aligns well with future development trends.
Implementation Method 1
The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input end. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first end of the rectifying element. The upper terminal of the second secondary winding is connected to the second end of the rectifying element, and the lower terminal of the second secondary winding is connected to the second output terminal.
Data Source
AI summary
A flyback converter with electromagnetic interference suppression function includes an input end, an output end, a rectifying element, and a transformer. The output end includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input end. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first end of the rectifying element. The upper terminal of the second secondary winding is connected to the second end of the rectifying element, and the lower terminal of the second secondary winding is connected to the second output terminal.