Spread Spectrum Switching Power Converter EMI Reduction
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Solution Overview
Problem
Power control systems generate significant electromagnetic interference (EMI) that can degrade performance, cause malfunctions, or lead to failure in electronic circuits, and existing technologies struggle to effectively reduce peak EMI values while maintaining power factor correction.
Innovation Solution
A controller modulates the period and pulse width of a switch control signal using a spread spectrum strategy to reduce peak EMI values, incorporating a spread spectrum module that varies the precursor period value to generate a varying period and pulse width of the control signal, thereby spreading the frequency spectrum and reducing EMI, while also providing power factor correction for switching power converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a switching power converter uses a fixed frequency control signal, then power factor correction is maintained, but electromagnetic interference peak values are high causing circuit degradation
Solution Approach 1:
The patent applies dynamics by making the control signal frequency variable rather than fixed. The spread spectrum module continuously varies the period of the control signal within a range centered around a nominal period, transforming the static frequency into a dynamic one. This frequency modulation spreads the EMI energy across a broader spectrum, reducing peak interference values while maintaining average power factor correction performance.
Solution Approach 2:
The patent changes the temporal parameter of the control signal by varying its period. The spread spectrum module modifies the period parameter within acceptable ranges, allowing the switching frequency to fluctuate dynamically. This parameter change approach redistributes the EMI spectral density without compromising the power converter's ability to maintain power factor correction.
2Object-affected harmful factors
If the control signal period is varied to reduce EMI, then electromagnetic interference is reduced, but power factor correction capability may be compromised
Solution Approach 1:
The patent employs periodic action through the spread spectrum modulation technique, where the control signal period varies in a controlled, periodic manner around a nominal value. This periodic variation in frequency spreads the EMI spectrum while the average periodic behavior maintains the power factor correction function. The modulation is designed to preserve the overall energy transfer characteristics necessary for PFC.
Solution Approach 2:
The patent incorporates feedback mechanisms where the controller monitors the output voltage and adjusts the control signal accordingly. The spread spectrum module receives feedback about the actual operating conditions and modifies the period variation to maintain power factor correction. This closed-loop feedback ensures that EMI reduction does not compromise the power converter's regulatory function.
Data Source
AI summary
Power control systems generate electromagnetic interference (EMI). In at least one embodiment, a power control system includes a switching power converter and a controller that utilizes a spread spectrum strategy to reduce peak EMI values of the power control system. The controller generates a power regulation, switch control signal to control an input voltage to output voltage conversion by the switching power converter. The controller modulates the period of the control signal in accordance with the spread spectrum strategy. The spread spectrum strategy is an intentional plan to spread the spectrum of the control signal to reduce peak EMI values, and, thus, reduce the potential for degradation in performance, a malfunction, or failure of an electronic circuit caused by the EMI. The controller also modulates a pulse width of the switch control signal in response to modulation of the period of the control signal to provide power factor correction.