Magnetic Sensor Device Switching Between Closed-Loop and Open-Loop Modes
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Solution Overview
Problem
Current magnetic sensors, particularly in inverter and battery apparatuses, face challenges in accurately measuring low-strength currents and detecting pulsed noise magnetic fields due to limitations in measurement range and response speed.
Innovation Solution
A magnetic sensor device with a control circuit that switches between closed-loop and open-loop operations based on the strength of the target magnetic field, using a magnetoresistive element and feedback coil to maintain a constant feedback current, enabling detection of pulsed noise magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic balance system is used to accurately measure low-strength currents, then measurement precision is improved, but response speed deteriorates
Solution Approach 1:
The patent implements dynamic switching between two operational modes (open-loop and closed-loop) based on the strength of the target magnetic field. When the magnetic field strength exceeds a threshold, the system switches to open-loop mode for fast response; when it falls below the threshold, the system switches to closed-loop mode for high precision measurement. This dynamic adaptation resolves the contradiction by selecting the appropriate operational mode according to real-time conditions.
2Adaptability or versatility
If a magnetic proportional system is used to increase measurement range, then measurement range is improved, but measurement precision in low-current domain deteriorates
Solution Approach 1:
The patent divides the measurement range into two segments: a first range (higher current values) handled by the magnetic proportional system, and a second range (lower current values) handled by the magnetic balance system. The control circuit automatically selects which system to use based on the detected magnetic field strength, ensuring both wide measurement range and high precision in the low-current domain are achieved simultaneously.
3Measurement precision
If closed-loop operation is used to maintain constant feedback current, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control circuit dynamically adjusts its operational mode based on the target magnetic field strength. In the first range, the control circuit implements closed-loop control to maintain constant feedback current for high precision. In the second range, it switches to open-loop mode where the feedback current varies naturally with the target magnetic field, simplifying the control mechanism while maintaining measurement accuracy through appropriate mode selection.
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 allows for accurate measurement of low-strength currents and effective detection of pulsed noise magnetic fields, enhancing the measurement range and response speed of magnetic sensors in inverter and battery systems.
Implementation Method 1
a magnetic detection element configured to detect an applied magnetic field, and generates a first detection signal having a correspondence with a strength of the applied magnetic field
Implementation Method 2
a feedback coil through which a feedback current is passed to generate a cancellation magnetic field for cancelling at least part of a target magnetic field
Data Source
AI summary
A magnetic sensor device includes a first detection circuit that generates a first detection signal, a coil through which a feedback current is passed to generate a cancellation magnetic field, a second detection circuit that generates a second detection signal having a correspondence with a value of the feedback current, and a control circuit that controls the feedback current. In a closed-loop operation, the control circuit controls the feedback current so that the first detection signal has a constant value. In an open-loop operation, the control circuit maintains the feedback current at a constant value.