Amorphous Wire Magnetic Impedance Sensor with Bipolar Pulse Compensation
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Solution Overview
Problem
Conventional magnetic impedance sensors face issues with non-linear characteristics due to incomplete return to the zero-magnetized state, leading to potential errors in magnetic field measurements, especially when using amorphous wires as magneto-sensitive materials.
Innovation Solution
The implementation of a magnetic impedance sensor that alternately supplies a basic pulse current and a compensating pulse current with opposite polarity to the amorphous wire, ensuring the magnetization passes through a zero-magnetized state, thereby avoiding non-linear characteristics and improving linear measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pulse current is periodically applied to the amorphous wire with binary values at two logic levels, then the magnetization is enforced in circumferential directions, but the magnetization does not completely return to the zero-magnetized state due to hysteresis, causing non-linear characteristics
Solution Approach 1:
The patent applies periodic pulse currents with alternating polarities to the amorphous wire. By switching between positive and negative logic levels, the magnetization is periodically enforced in opposite circumferential directions, ensuring that residual magnetization from hysteresis is canceled out and the wire returns to a zero-magnetized state before each measurement cycle.
Solution Approach 2:
The patent inverts the conventional approach by using bipolar pulse currents (both positive and negative) instead of unipolar currents. This inversion allows the magnetization to be enforced in both u and v circumferential directions alternately, ensuring that any residual magnetization is reversed and eliminated, thereby achieving linear characteristics regardless of the wire type.
2Measurement precision
If the magnetization starts from a non-zero state due to incomplete return to zero-magnetized state, then measurement errors occur, but applying additional compensation current increases energy consumption
Solution Approach 1:
The system uses the pulse current itself to serve dual purposes: both to enforce magnetization for measurement and to compensate for residual magnetization through alternating polarities. The same pulse generator that creates the measurement signal also provides the compensation function by switching between positive and negative logic levels, eliminating the need for separate compensation circuits.
Solution Approach 2:
By implementing periodic bipolar pulse currents, the system automatically resets the magnetization state to zero at the end of each cycle. This periodic resetting ensures that measurements always start from a known zero state without requiring additional energy-consuming compensation operations, as the alternating current naturally cancels residual magnetization.
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 approach results in a magnetic sensor with excellent linear characteristics, reducing measurement errors and energy consumption by ensuring the magnetization starts from a zero state, enhancing the accuracy and efficiency of magnetic field detection.
Implementation Method 1
an alternate current voltage is generated in response to a magnetic field intensity around the amorphous wire by a magnetic impedance effect of the amorphous wire according to the pulse current
Implementation Method 2
a magnetizing force is generated according to the right-handed screw rule and magnetization in the circumferential direction of the amorphous wire is constrained
Data Source
Figure 1~5
Figure 2(a)~3
Figure 4~7
AI summary
A magnetic impedance sensor comprises an amorphous wire 1 of a magneto-sensitive material as the magneto-impedance element, a pulse oscillator means 2 that alternately reverses and outputs a basic pulse current and a compensating pulse current with polarity opposite to the basic pulse current in predetermined periods, and a signal processing means 3 that converts an alternate current voltage generated in response to a magnetic field intensity around the amorphous wire by a magnetic impedance effect of the amorphous wire according to the pulse current into a magnetic signal voltage in response to the magnetic field intensity, and outputs the magnetic signal voltage. Since the amorphous wire 1 is repeatedly reversely magnetized in the u and v circumferential directions, due to compensating the negative pulse current, the magnetic sensor with excellent linear characteristics are obtained.