Closed-Loop Current Sensor Degaussing for Residual Magnetism Offset
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Solution Overview
Problem
Closed-loop current sensors face issues with residual magnetism due to unaddressed degaussing, leading to offset outputs and component errors, particularly during power outages or external magnetic field inductions.
Innovation Solution
A closed-loop current sensor performs internal degaussing upon power-on without additional coils or hardware, using a control unit to generate alternating currents and magnetic fields with controlled duty cycles to eliminate residual magnetism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If degaussing is not performed in the initial state, then the device complexity is reduced, but the measurement precision deteriorates due to offset caused by residual magnetism
Solution Approach 1:
The patent applies preliminary action by performing degaussing operation automatically when the power is turned on, before any measurement is taken. The control unit generates a degaussing current that gradually decreases to eliminate residual magnetism in the iron core, ensuring the magnetic field returns to zero. This preliminary degaussing action prevents offset errors in subsequent measurements without requiring additional hardware circuits.
2Measurement precision
If additional coils or hardware circuits are added to perform degaussing, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by making the existing coil serve multiple functions: it acts as both the sensing coil for normal current measurement and the degaussing coil for eliminating residual magnetism. The control unit generates a degaussing current through the same coil structure, eliminating the need for separate degaussing coils or additional hardware circuits while maintaining measurement precision.
Solution Approach 2:
The system applies self-service by using its own existing components (the coil and control unit) to perform the degaussing function without external assistance. The control unit automatically generates the degaussing current and controls the gradual decrease of magnetic field, enabling the sensor to self-correct residual magnetism issues without requiring external degaussing equipment.
3Measurement precision
If the operating point of the magnetic field is kept at zero in closed-loop mode, then the measurement precision is improved, but the reliability deteriorates due to offset from residual magnetism during power outage
Solution Approach 1:
The patent applies preliminary action by performing automatic degaussing when power is restored after an outage. The control unit detects the power-on state and immediately generates a degaussing current that gradually decreases to eliminate residual magnetism accumulated during the power outage. This ensures the magnetic field returns to zero before normal measurement operations resume, maintaining both precision and reliability.
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
The solution ensures fast response and reduces electromagnetic interference, power consumption, and eliminates the need for additional circuits, maintaining accurate readings by eliminating residual magnetism.
Implementation Method 1
the driving circuit is configured to generate an alternating current signal, so as to generate positive and negative currents with a decreasing peak value on the coil and generate positive and negative magnetic fields with a decreasing peak value on the iron core for degaussing
Data Source
AI summary
A closed-loop current sensor is provided. The under-test current conversion unit inputs an under-test current, and generates an analog signal and a voltage output signal. The first signal conversion unit converts the analog signal into a magnetic flux signal. The second signal conversion unit converts the voltage output signal into a digital voltage output signal. In an open-loop state, the control unit outputs a control signal with a first duty cycle, and controls the current value of the under-test current conversion unit. The voltage output signal is a first reading value, and the analog signal is the residual magnetism value of the under-test current conversion unit. In the open-loop state, the driving circuit generates an alternating current on the coil as well as generates positive and negative currents and magnetic fields with a decreasing peak value on the under-test current conversion unit for degaussing.