Switch-Mode Power Supply Frequency Hopping for EMI Reduction
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Solution Overview
Problem
Conventional control signals for switch-mode power supplies have a low frequency-domain energy dispersion degree, leading to high electromagnetic interference and failure in security tests.
Innovation Solution
A control circuit that adjusts the frequency of control signals in multiple cycles with random duration and amplitude ranges, reducing periodicity and maximizing frequency-domain energy dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control signal with fixed cycle is sent to switch-mode power supply, then the frequency-domain energy is concentrated, but the maximum energy value becomes too high to pass security tests
Solution Approach 1:
The patent applies periodic frequency hopping where the control signal switches between different frequency points in a periodic manner. This periodic action disperses the concentrated frequency-domain energy across multiple frequency points, reducing the maximum energy value at any single frequency while maintaining effective power supply control, thereby reducing electromagnetic interference and enabling passage of security tests.
Solution Approach 2:
The patent changes the frequency parameter of the control signal dynamically by implementing frequency hopping among multiple frequency points. This parameter change transforms the fixed-frequency control signal into a variable-frequency signal, dispersing energy across the frequency spectrum and reducing peak energy values that cause electromagnetic interference.
2Object-affected harmful factors
If linear spectrum spreading is applied to disperse frequency-domain energy, then the maximum energy value is reduced, but the energy dispersion degree remains insufficient
Solution Approach 1:
The patent segments the frequency spectrum into multiple discrete frequency points and distributes the control signal energy across these segmented frequency points through frequency hopping. This segmentation approach achieves superior energy dispersion compared to conventional linear spectrum spreading, significantly reducing both the maximum energy value and improving the overall energy dispersion degree.
Data Source
AI summary
A control circuit for a switch-mode power supply, a power circuit, and an electronic device. The control circuit outputs a control signal to control a switching frequency of the switch-mode power supply. The control circuit adjusts, in a plurality of cycles, a frequency of the control signal based on a plurality of ranges, and controls, in each cycle, the frequency of the control signal to change with time in a range corresponding to each cycle. In the embodiments, a frequency-domain energy dispersion degree of the control signal output by the control circuit can be increased, electromagnetic interference generated by the control signal output by the control circuit is reduced, and finally, it is ensured that the power circuit and the electronic device including the power circuit can pass a related security test.