Current Measurement Circuit for Separate AC/DC Sensing
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Solution Overview
Problem
Current measurement devices experience phase delays in the AC component of the feedback current relative to the AC component of the measurement target current, leading to adverse effects, and are unable to separately measure DC and AC components of the measurement target current.
Innovation Solution
The device includes an AC measurement circuit that measures the AC component based on the feedback voltage, a low-pass filter to remove AC components from the feedback voltage, and a DC measurement circuit to measure the DC component based on the filtered feedback current, thereby eliminating phase delays and allowing separate measurement of DC and AC components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback current is generated based on feedback voltage to counteract core magnetic flux, then the core magnetic flux can be suppressed, but a phase delay occurs in the AC component of the feedback current relative to the AC component of the measurement target current when the frequency is high
Solution Approach 1:
The patent segments the measurement of AC and DC components into separate circuits. The AC measurement circuit measures the AC component based on feedback voltage without going through the current adjustment circuit, while the DC measurement circuit measures the DC component based on feedback current. This segmentation eliminates the phase delay issue for AC measurements while maintaining DC suppression capability.
Solution Approach 2:
The patent extracts the AC component measurement function from the feedback current path. By measuring the AC component directly from the feedback voltage in a separate AC measurement circuit, the invention removes the AC component from the feedback current path that would cause phase delay, allowing accurate AC measurement without timing errors.
2Reliability
If feedback current includes both DC and AC components, then the core magnetic flux can be counteracted, but the measurement circuit cannot separately measure the DC and AC components of the measurement target current
Solution Approach 1:
The patent divides the measurement system into two independent measurement circuits: an AC measurement circuit that measures only the AC component based on feedback voltage, and a DC measurement circuit that measures only the DC component based on feedback current. This segmentation enables separate measurement of DC and AC components while maintaining the ability to counteract magnetic flux.
Solution Approach 2:
The patent extracts the AC component measurement from the feedback current path by using the feedback voltage directly in the AC measurement circuit. This allows the AC component to be measured separately without being mixed with the DC component in the feedback current, enabling precise separate measurement of both components.
3Temperature
If the core cross-sectional area is made smaller, then heat generation and magnetic saturation are suppressed, but the core magnetic flux cannot be sufficiently counteracted without adequate feedback current
Solution Approach 1:
The patent segments the feedback function into two independent paths: one for DC component (through current adjustment circuit) and one for AC component (through direct voltage measurement). This allows the core to be designed with smaller cross-sectional area for heat suppression while maintaining effective magnetic flux counteraction through coordinated DC and AC feedback.
Solution Approach 2:
The patent changes the approach to feedback by separately handling DC and AC components with different measurement and adjustment methods. This allows optimization of core parameters (like cross-sectional area) for heat suppression while maintaining effective magnetic flux counteraction through precise separate control of DC and AC feedback.
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 suppresses adverse effects from phase delays and enables accurate, separate measurement of DC and AC components in the measurement target current, improving measurement precision and accuracy.
Implementation Method 1
an element that generates a feedback voltage, based on core magnetic flux that is a magnetic flux flowing along the core
Implementation Method 2
a coil externally fitted around the core
Data Source
AI summary
An object is to separately measure the DC and AC components included in a measurement target current. The current measurement device includes a core, a coil, an element, an AC measurement circuit, a low-pass filter, a current adjustment circuit, and a DC measurement circuit. The core allows magnetic flux to flow therethrough due to the measurement target current. The element generates a feedback voltage, based on the magnetic flux flowing along the core. The AC measurement circuit measures the AC component of the measurement target current, based on the feedback voltage. The current adjustment circuit allows a feedback current to flow through the coil, counteracting the DC component of the core magnetic flux, based on the feedback voltage from which the AC component has been removed by the low-pass filter. The DC measurement circuit measures the DC component of the measurement target current, based on the feedback current.