Power Converter Frequency Smearing for Emission Reduction
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Solution Overview
Problem
Existing resonant-type power converters lack synchronization capabilities with external signals and do not facilitate frequency smearing, which limits their efficiency and increases electromagnetic emissions.
Innovation Solution
A power converter with a fixed ratio DCDC transformer section incorporating an LLC resonant converter and a control circuit that adjusts the operating frequency over a limited range relative to the resonant frequency, enabling synchronization and frequency smearing to reduce electromagnetic emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power converter operates at a fixed resonant frequency, then the efficiency is maximized through zero-current switching and zero-voltage switching, but the synchronization capability with external signals is lost and electromagnetic emissions concentrate at spectral peaks
Solution Approach 1:
The patent applies dynamics by making the operating frequency adjustable rather than fixed. The control circuit dynamically varies the operating frequency around the resonant frequency based on synchronization requirements, allowing the system to adapt between maintaining peak efficiency at resonant frequency and achieving synchronization when needed.
Solution Approach 2:
The patent changes the frequency parameter dynamically. By varying the operating frequency around the resonant frequency under control circuit regulation, the system can shift between operating modes - maintaining optimal efficiency at the resonant peak while enabling synchronization capability through frequency modulation.
2Loss of energy
If the power converter operates at a fixed resonant frequency, then the gate driving power requirement is minimized through resonant transition types, but frequency smearing capability is lost which increases electromagnetic emissions
Solution Approach 1:
The patent applies periodic action through frequency modulation. The control circuit periodically varies the operating frequency around the resonant frequency, creating frequency smearing that spreads electromagnetic emissions across a broader spectrum rather than concentrating them at a single peak frequency.
Solution Approach 2:
The system dynamically adjusts the operating frequency to achieve frequency smearing. By making the frequency variable rather than fixed, the converter can spread its spectral content while still operating near the resonant frequency to maintain low gate driving power requirements.
3Adaptability or versatility
If the operating frequency is varied over a wide range, then synchronization and frequency smearing capabilities are improved, but the efficiency is reduced due to deviation from optimal resonant operation
Solution Approach 1:
The patent applies partial action by limiting the frequency variation to a small range around the resonant frequency rather than allowing wide deviations. This partial frequency modulation provides sufficient synchronization capability and frequency smearing while minimizing the impact on efficiency.
Solution Approach 2:
The system makes small, controlled changes to the frequency parameter around the resonant point. This limited parameter variation achieves the desired synchronization and electromagnetic emission reduction while maintaining operation close to the optimal efficiency point.
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 configuration allows for improved synchronization across stages, reduces electromagnetic emissions by spreading spectral peaks, and enhances efficiency by minimizing power losses.
Implementation Method 1
resonant-type power conversion can improve the efficiency of a power converter. Two known approaches that are particularly appropriate are resonant converters that can achieve zero-current switching (ZCS) and zero-voltage switching (ZVS)
Implementation Method 2
there is provided a control circuit operable to alter the operating frequency of the power converter over a limited range with respect to the resonant frequency
Data Source
AI summary
The present invention relates to a power converter (90) and a method of operating same. There are numerous advantages to operating power converters using a series resonant converter (1, 21). This approach is particularly suitable for minimizing switching losses in the power converter when it is operated at high frequency. However, there are problems with the known converters in that they are prone to generate noise in the acoustic spectrum due to the fact that the converter stages are often operating at different frequencies. The present invention relates to a power converter and a method of operating same that enables the operating frequency of the converter to be controlled by a control circuit over a predetermined range of the resonant frequency. This allows reduction in acoustic noise generation and facilitates frequency smearing that will in turn reduce spectral peaks. This is achieved while maintaining output ripple within acceptable ranges.