Switched-Mode Power Supply Frequency Modulation for Synchronization Prevention
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Solution Overview
Problem
Switched-mode power supplies with multiple output stages often experience undesired synchronization due to magnetic and capacitive coupling, leading to fluctuations and flicker in LED lighting, which conventional methods struggle to prevent, especially when covering a large output current and voltage range.
Innovation Solution
The implementation of a modulation unit that generates a modulation signal to be combined with the switching signal for driving the switching element in at least one output stage, preventing synchronization by ensuring a frequency difference greater than the coupling between the stages, thereby preventing phase convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If output stages are operated at significantly different frequencies to avoid synchronization, then synchronization effects are prevented, but the ability to cover large output current and voltage range is compromised
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control unit dynamically adjusts the switching frequency of the output stages based on operating conditions, allowing the system to maintain frequency separation to prevent synchronization while adapting to different output current and voltage requirements. This resolves the contradiction by enabling frequency modulation that prevents synchronization effects while maintaining adaptability across operating ranges.
Solution Approach 2:
The patent changes the frequency parameter dynamically through control units that modulate the switching frequency of each output stage. By varying the frequency parameter in response to operating conditions, the system prevents synchronization effects (maintaining reliability) while covering the required output current and voltage range (maintaining adaptability). The control unit monitors operating parameters and adjusts frequency accordingly.
2Volume of moving object
If output stages are placed close together for compact design, then device size is reduced, but magnetic and capacitive coupling increases causing synchronization
Solution Approach 1:
The patent converts the harmful coupling effect into a beneficial control parameter. Instead of trying to eliminate magnetic and capacitive coupling through physical separation, the control unit exploits the coupling by actively modulating the switching frequencies to maintain frequency separation. This approach allows compact design with close placement of output stages while using the coupling effects as part of the control mechanism to prevent synchronization.
Solution Approach 2:
The control unit acts as an intermediary that manages the interaction between closely placed output stages. It introduces frequency modulation as a mediating mechanism that prevents direct synchronization caused by magnetic and capacitive coupling, allowing the stages to be placed close together for compact design while maintaining operational independence through active frequency control.
3Reliability
If frequency modulation is applied to prevent synchronization, then synchronization effects are reduced, but control complexity increases
Solution Approach 1:
The patent implements feedback control where control units monitor the operating conditions and output parameters of each stage, then adjust the switching frequencies accordingly. This feedback mechanism automatically maintains frequency separation to prevent synchronization without requiring complex external control systems. The feedback loops within each control unit handle the frequency modulation locally, reducing overall system complexity while maintaining reliable synchronization prevention.
Data Source
AI summary
In various embodiments, a switched-mode power supply is provided. The switched-mode power supply includes at least two output stages. Each output stage has a converter. A frequency of at least one of the output stages is modulated by way of a modulation unit configured to provide a modulation signal that is combined with a switching signal for driving a switching element of the converter of the at least one output stage.