Three-Phase Current Sensor Using Segmented Magnetic Circuits
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Solution Overview
Problem
Existing three-phase current sensors face challenges in measuring strong currents due to magnetic saturation and bulkiness, particularly in applications like electric motor vehicles, where high powers and low voltages require efficient and cost-effective solutions that minimize the influence of external magnetic fields.
Innovation Solution
A compact three-phase current sensor design featuring two magnetic measurement devices with multiple gaps and Hall effect sensors positioned on either side of a central conductor, allowing for precise current measurement across all phases without saturating the magnetic circuits, and incorporating a common supporting plate for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the section of the magnetic circuit is increased to avoid saturation, then the measurement precision is improved, but the weight and volume of the sensor increase
Solution Approach 1:
The magnetic circuit is divided into multiple segments with individual magnetic circuits for each phase conductor. Each magnetic circuit measures the magnetic field generated by its corresponding phase, allowing the system to handle strong currents without requiring a single large magnetic circuit that would increase weight and volume.
Solution Approach 2:
The patent combines the measurement of multiple phases into a single integrated sensor assembly. By positioning magnetic circuits around multiple conductors and processing their combined signals, the system achieves accurate measurement of strong three-phase currents while maintaining a compact structure that reduces overall weight compared to individual sensors for each phase.
2Measurement precision
If the section of the magnetic circuit is increased to avoid saturation, then the measurement precision is improved, but the cost of the sensor increases
Solution Approach 1:
Instead of using one large expensive magnetic circuit, the system uses multiple smaller magnetic circuits that can be manufactured more economically. Each magnetic circuit is sized appropriately for its specific measurement task, reducing material costs and manufacturing complexity while maintaining measurement precision through signal combination.
3Reliability
If magnetic field sensors are positioned around each of the three phases to detect leakage currents, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent integrates three phase measurements into a single sensor assembly with shared structural components and signal processing circuitry. While maintaining the ability to detect currents in all three phases for leakage detection, the design reduces overall complexity through common magnetization coils, shared magnetic path elements, and integrated signal processing that combines measurements from all phases.
4Volume of moving object
If the conductors of the three phases are brought closer to each other to reduce bulkiness, then the volume is reduced, but the magnetic saturation problem worsens due to added magnetic fields from adjacent conductors
Solution Approach 1:
The system segments the measurement function so that each magnetic circuit primarily detects the magnetic field of its corresponding phase conductor. This segmentation allows conductors to be positioned closer together without the magnetic fields from adjacent conductors causing saturation, because each magnetic circuit is optimized to measure its specific phase while the segmented architecture isolates the measurement functions.
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 provides accurate, cost-effective, and compact current measurement for high-intensity currents, reducing sensitivity to external fields and enabling precise measurement across a wide current range without magnetic saturation, suitable for applications in electric motor vehicles.
Implementation Method 1
A very widespread magnetic field sensor is a Hall effect sensor integrated into an ASIC with terminals for its connection to a printed circuit for processing the signals
Data Source
AI summary
A three-phase current sensor for measuring currents (IPH1, IPH2, IPH3) running in three conductors of a three-phase conductor system comprises a first magnetic measuring device (D1) and a second magnetic measuring device (D3). Each magnetic measuring device comprises a magnetic circuit provided with at least two interleaf gaps and a magnetic field sensor arranged in each interleaf gap. The magnetic measuring devices (D1, D3) are positioned on both sides of a central conductor or cavity, thereby enabling a central conductor to be inserted in such a way that one of three phases of the conductor system is formed.