Three-Phase Current Sensor Layout Without Shield Members
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Solution Overview
Problem
Existing current measurement devices suffer from increased size, decreased accuracy, and prolonged calculation times due to the presence of a shield member and complex calculations, which affect responsiveness.
Innovation Solution
A current sensor design featuring three-phase busbars with sensor units and magnetism detection elements arranged to detect magnetic fields, calculating current values using differential output values without a shield member, allowing for reduced size and improved accuracy and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shield member is provided in the current measurement device, then the device structure is completed, but the size of the device increases and measurement accuracy decreases
Solution Approach 1:
The patent removes the shield member from the device structure entirely. The current measurement device measures currents without requiring a shield member, thereby reducing device size while maintaining measurement accuracy through alternative measurement arrangements using multiple coreless current sensors and calculation units.
Solution Approach 2:
The calculation unit performs multiple functions: it calculates current values from sensor outputs, applies compensation based on predetermined coefficients, and determines both individual conductor currents and total current. This multi-functional approach replaces the need for separate shield members and simplifies the overall device structure.
2Reliability
If a shield member is provided in the current measurement device, then the device structure is completed, but the measurement accuracy of currents decreases due to influence of the shield member
Solution Approach 1:
The shield member is completely removed from the device. The patent achieves accurate current measurement without any shield member by using multiple coreless current sensors positioned at specific locations and applying mathematical calculations with predetermined coefficients to compensate for mutual influences between sensors.
Solution Approach 2:
Instead of trying to block the mutual influence between sensors with a shield member, the patent converts this harmful effect into a beneficial one by using the predetermined coefficients to mathematically compensate for the influence. The calculation unit applies these coefficients to accurately determine individual conductor currents even in the presence of mutual sensor interference.
3Productivity
If current values are calculated based on parameters acquired in advance, then measurement can be performed, but complicated calculation is required and responsiveness decreases
Solution Approach 1:
The predetermined coefficients are pre-calculated and stored in the calculation unit based on the geometric relationships between sensors and conductors. During actual measurement, the calculation unit simply applies these pre-computed coefficients to the sensor outputs, avoiding complex real-time calculations and achieving both accuracy and responsiveness.
Solution Approach 2:
The patent transforms the complex measurement problem into a simpler one by changing the parameters from direct current measurement to measuring magnetic field influences and using predetermined coefficients. This parameter transformation simplifies the calculation process while maintaining measurement accuracy.
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 current sensor achieves enhanced measurement accuracy and responsiveness while minimizing overall size by eliminating the need for a shield member and simplifying calculations, utilizing magnetism detection elements and differential output values.
Implementation Method 1
The first magnetism detection element and the second magnetism detection element each have a sensitivity axis along a third direction orthogonal to the first direction and the second direction, are arranged in the second direction, and detect magnetic fields generated by currents flowing through the first busbar, the second busbar, and the third busbar
Data Source
AI summary
A current sensor includes a first busbar, a second busbar, and a third busbar, a first sensor unit, a second sensor unit and a calculating unit. The first, second and third busbars extend in a first direction apart from each other and are arranged in a second direction orthogonal to the first direction. Three-phase alternating currents flow through the first, second and third busbars. The first sensor unit is located between remaining two busbars other than one busbar to be measured among the first, second and third busbars. The second sensor unit measures one of the remaining two busbars other than the one busbar to be measured and is located between the one busbar to be measured and the other one of the remaining two busbars. The calculating unit calculates current values of the first, second and third busbars from output values of the first and second sensor units.