Secondary-Side Mains Sensing During Burst-Mode Power Conversion
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Solution Overview
Problem
Existing LED driver systems struggle to accurately measure mains voltage and frequency from the secondary side, especially when the power supply input stage operates in burst mode, due to galvanic isolation and the lack of direct linkage between burst operation and mains voltage/frequency.
Innovation Solution
A power supply system with a secondary side controller that determines the peak voltage and/or frequency of the secondary side winding and instructs the primary side controller to switch from burst mode to standard mode, allowing accurate measurement of mains voltage and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the converter operates in burst mode to improve efficiency under light load conditions, then energy efficiency is improved, but the accuracy of mains voltage and frequency measurement from the secondary side deteriorates
Solution Approach 1:
The system temporarily switches from burst mode to standard mode before performing mains voltage and frequency measurements. This preliminary action ensures that the converter is operating in a mode where the relationship between switching cycles and mains cycles is established, enabling accurate measurements. After measurement, the system can return to burst mode for efficient operation.
2Reliability
If galvanic isolation is implemented between primary and secondary sides to improve safety and electrical isolation, then safety and isolation are improved, but the ability to directly sense mains voltage and frequency from the secondary side deteriorates
Solution Approach 1:
The system uses feedback from the secondary side controller to the primary side controller to indirectly obtain mains voltage and frequency information. The secondary side controller measures parameters during standard mode operation and communicates this information back, allowing the primary side controller to determine mains characteristics without direct galvanic connection.
Solution Approach 2:
The patent uses the converter's switching operation as an intermediary to transfer information about mains voltage and frequency from the primary side to the secondary side. During standard mode, the switching frequency and timing are directly related to the mains frequency, allowing the secondary side to infer mains parameters through measurements of the converter's operation.
3Measurement precision
If the secondary side controller continuously monitors mains parameters to improve measurement accuracy, then measurement accuracy is improved, but the complexity of the control system increases
Solution Approach 1:
Instead of continuous monitoring, the system performs mains parameter measurements periodically by temporarily switching to standard mode at specific intervals. This periodic approach reduces the complexity of continuous monitoring circuitry while still providing accurate measurements at appropriate intervals for diagnostic purposes.
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
Enables accurate determination of mains voltage and frequency from the secondary side, even when the power supply is in burst mode, by ensuring the primary side operates in standard mode long enough to capture these parameters.
Implementation Method 1
a transformer having a primary side winding and a secondary side winding, the transformer defining a primary side and the secondary side of the power supply, the primary side being galvanically isolated from the secondary side
Data Source
AI summary
A secondary side controller configured to determine a peak voltage and/or a frequency of a secondary side winding of a power supply converter over a predetermined period of time, wherein, when the converter is in the burst mode, the secondary side controller is configured to instruct a primary side controller to increase the set point, such that the primary side controller operates in the standard mode to increase the converted output voltage, the secondary side controller determining the peak voltage and/or the frequency of the secondary side winding while the primary side controller is operating the converter in the standard mode.