Three-Phase Current Sensing Layout for Low Inductance Wiring
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Solution Overview
Problem
The challenge is to design a current detection device that can achieve low resistance and low inductance for wiring between a three-phase inverter and a motor, while accommodating a current detection circuit substrate, and preventing high-frequency current radiation.
Innovation Solution
The solution involves arranging insulation-coated base materials in close contact, with resistors and measurement terminals on non-coated areas, allowing substrates to be mounted and fixed in opposing positions, and enclosing them in an insulating case with a conductive outer surface to shield high-frequency currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If three shunt resistors are stacked to achieve low resistance and low inductance, then electrical loss is reduced and high frequency current radiation is prevented, but a substrate for mounting the current detection circuit cannot be arranged
Solution Approach 1:
The patent applies nesting by placing the substrate (5, 6) inside the hollow interior space of the insulating case (7), which itself surrounds the stacked shunt resistors (20, 30). This nested arrangement allows the substrate to be positioned within the existing structure without increasing the overall footprint or compromising the low-inductance stacking configuration, thereby resolving the contradiction between achieving low electrical loss and accommodating the detection circuit substrate
2Object-affected harmful factors
If three shunt resistors are stacked to achieve low inductance, then high frequency current radiation is prevented, but a substrate for mounting the current detection circuit cannot be arranged
Solution Approach 1:
The substrate is nested within the insulating case that surrounds the stacked shunt resistors, allowing the detection circuit to be housed within the existing low-inductance structure. This eliminates the need for separate substrate mounting arrangements that would disrupt the closely attached wiring configuration, thus maintaining low inductance while accommodating the substrate
3Object-affected harmful factors
If wiring is closely attached to achieve low inductance, then high frequency current radiation is prevented, but the wiring becomes more complex and harder to manufacture
Solution Approach 1:
The patent merges the wiring structure with the insulating case by having the case envelop the closely attached wiring and shunt resistors. This integration simplifies manufacturing by combining multiple functions (insulation, structural support, and wiring arrangement) into a single component, reducing the complexity of assembling closely attached wiring while maintaining low inductance characteristics
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
This configuration satisfies the demands for low resistance and low inductance, enabling effective current detection while preventing radiation of high-frequency currents, thus enhancing the performance of the current detection device.
Implementation Method 1
the insulating case (7) has the outer peripheral surface (7a) made conductive, the first substrate (5) and the second substrate (6) are also shielded, so that the high frequency current can be prevented from radiating to the surroundings
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
[Problem] An object of the present invention is to provide a current detection device capable of satisfying the demands for low resistance and low inductance. [Solution] A current detection device 1 has a plurality of base materials (a first base material 2, a second base material 3, and a third base material 4) that are coated with insulation and connected between a three-phase inverter and a motor. The plurality of base materials (the first base material 2, the second base material 3, and the third base material 4) include the first base material 2, the second base material 3, and the third base material 4. The first base material 2 is disposed on the upper surface of the third base material 4 in close contact therewith and comprises, in a section which is not coated with insulation, a first resistor 20, and a first measurement terminal 21 which are fixed atop the first base material 2. The second base material 3 is disposed on the lower surface of the third base material 4 in close contact therewith and comprises, in a section which is not coated with insulation, a second resistor 30, and second measurement terminals 31 which are fixed atop the second base material 3.