Zero-Flux Current Sensor Circuit for Wideband DC Detection
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Solution Overview
Problem
Existing current sensors cannot detect direct current effectively beyond a predetermined high frequency band due to negative feedback currents flowing through parallel resistors, impairing detection accuracy in low frequency bands.
Innovation Solution
A current sensor of a zero flux type with a magnetic core, magnetic detection element, and feedback circuit, incorporating connection circuits and resistors connected in parallel to winding sections, which block direct current components from low frequency bands, allowing negative feedback operations across a wider frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If resistors are connected in parallel to winding sections to extend high frequency detection, then detection frequency band is improved, but negative feedback operation fails in low frequency band
Solution Approach 1:
A connection circuit is introduced as an intermediary component between the resistor and the winding section. This connection circuit includes a capacitor that acts as a frequency-selective mediator, allowing the resistor to be effectively connected only in the high frequency band while blocking it in the low frequency band, thus resolving the contradiction between extending detection bandwidth and maintaining feedback reliability
Solution Approach 2:
The connection circuit dynamically changes the effective impedance of the parallel resistor based on frequency. At low frequencies, the capacitor blocks the resistor from affecting the winding section, preserving negative feedback operation. At high frequencies, the capacitor allows the resistor to be connected, enabling extended frequency detection. This dynamic behavior resolves the contradiction by adapting the circuit configuration to different operating conditions
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 detection of currents from direct current to a frequency band higher than the predetermined high frequency band without impairing detection accuracy in low frequency bands, while suppressing external magnetic field interference.
Implementation Method 1
a magnetic detection element incorporated in the magnetic core and configured to detect a magnetic flux generated in the magnetic core
Implementation Method 2
a feedback circuit configured to output, based on a signal input from the magnetic detection element, a negative feedback current for canceling out the magnetic flux generated in the magnetic core by the measurement current
Implementation Method 3
a winding wound around the magnetic core and configured to receive the negative feedback current from one end, detect a magnetic flux flowing through the magnetic core, and output from the other end a detection current indicating the measurement current
Data Source
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AI summary
A current sensor includes a magnetic detection element configured to detect a magnetic flux generated in a magnetic core, a feedback circuit configured to output, based on a signal input from the magnetic detection element, a negative feedback current for canceling out the magnetic flux generated in the magnetic core. The current sensor includes a winding wound around the magnetic core and configured to receive the negative feedback current from one end, detect a magnetic flux flowing through the magnetic core, and output a detection current indicating a measurement current from the other end. The current sensor includes a plurality of connection circuits configured to block components from a direct current to a low frequency band, and a plurality of resistors connected in parallel to a plurality of winding sections that constitute the winding and are connected in series. Each of the plurality of connection circuits is connected between a connection point between adjacent resistors among the plurality of resistors and a connection point between adjacent winding sections, and between an output end of the feedback circuit and a resistor connected to the output end.