Self-Powered CT Current Sensing With Switching and Self-Calibration
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Solution Overview
Problem
Conventional current sensors face challenges in miniaturization and high cost due to complex circuit designs requiring additional power sources, which result in intermittent sampling and high power consumption, making it difficult to detect sudden current changes and compromising sampling precision.
Innovation Solution
A current sensor unit with a rectification module, power source conversion module, mode switching module, current sensor module, and control module that converts AC current to pulsed DC, stores energy, and switches between charging and energy release modes to provide continuous detection while optimizing power usage and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional power source is used to supply power to electronic components, then power supply stability is improved, but device complexity and cost increase
Solution Approach 1:
The mutual inductor is designed to perform dual functions: current sensing and power supply. By extracting power from the secondary side of the mutual inductor during periods when current measurement is not required, the patent eliminates the need for separate power sources while maintaining both sensing and power supply functions within a single component
Solution Approach 2:
The patent combines the power supply function with the current sensing function by using the same mutual inductor for both purposes. The power is derived from the secondary side of the mutual inductor, merging what would traditionally be separate systems into one integrated solution
2Device complexity
If time division multiplexing is used to share mutual inductor for power supply and sampling, then device complexity is reduced, but sampling continuity deteriorates
Solution Approach 1:
The patent employs periodic action by using different time periods for power supply and current sampling. During specific time intervals, the mutual inductor secondary side is connected to power supply circuits, while during other intervals, it is connected to sampling circuits. This periodic switching ensures both functions receive adequate service without continuous interference
Solution Approach 2:
The system dynamically switches the connection of the mutual inductor secondary side between power supply mode and sampling mode based on real-time requirements. This dynamic allocation allows the system to adapt to varying power and measurement needs while maintaining operational continuity
3Reliability
If continuous power supply is provided to electronic components, then power supply stability is improved, but power consumption increases
Solution Approach 1:
Instead of continuous power supply, the patent implements periodic power supply through the mutual inductor. Power is supplied in intervals when current sampling is not required, reducing overall power consumption while maintaining sufficient power availability for electronic components during active periods
Solution Approach 2:
The patent applies partial action by providing power supply only during specific time intervals rather than continuously. This partial power supply approach is sufficient to maintain electronic component operation while significantly reducing total energy consumption compared to continuous supply
4Device complexity
If secondary-side DC impedance with non-fixed equivalent impedance is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent implements feedback mechanisms to monitor and compensate for variations in secondary-side DC impedance. By detecting changes in equivalent impedance and adjusting operating parameters accordingly, the system maintains measurement precision despite the non-fixed nature of the impedance
Solution Approach 2:
The system dynamically adjusts operating parameters in response to changes in secondary-side DC impedance. By modifying measurement parameters based on the current impedance state, the patent maintains sampling precision across varying impedance conditions without requiring fixed impedance characteristics
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 continuous current detection, prevents sudden current changes, improves sampling precision, and reduces power consumption, while incorporating a self-calibration function for long-term accuracy in harsh conditions.
Implementation Method 1
a rectification module, configured to convert an AC current to a pulsed DC current
Implementation Method 2
a power source conversion module containing an energy storage element, connected to the rectification module and configured to store energy for the energy storage element based upon the pulsed DC current
Implementation Method 3
a current sensor module, connected to the rectification module, the power source conversion module and the mode switching module separately and configured to detect a pulsed DC current flowing back from the power source conversion module or a pulsed DC current flowing back from the mode switching module
Data Source
AI summary
In an embodiment, a current sensor unit includes: a rectification module, to convert an AC current to a pulsed DC current; a conversion module containing an energy storage element, to store energy based upon the pulsed DC current during a charging mode and generate a power supply current; a switching module, bypassed by the conversion module during the charging mode, and bypassing the conversion module during an energy release mode; a current sensor module, to detect a pulsed DC current; a control module, to acquire electrical energy from the power supply current, determine operation in the charging mode or energy release mode, and acquire a first detection value provided by the current sensor module; and a self-calibration module, to generate a current flowing through the current sensor module in a self-calibration process, the control module calibrating the first detection value based upon a second detection value of the current generated.