Shielded Neutral-Point Wiring in Power Converters for Noise Reduction
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Solution Overview
Problem
Existing power conversion apparatuses generate noise due to switching control of upper- and lower-arm switches, which is transmitted externally and not effectively mitigated.
Innovation Solution
A power conversion apparatus with an inverter, rotating electric machine, neutral-point wiring, and a case that houses at least the inverter, featuring a shield function, where the neutral-point wiring is housed inside the case to reduce external noise emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching control of upper- and lower-arm switches is performed to drive the rotating electric machine, then the rotating electric machine can be driven effectively, but noise is generated and transmitted externally
Solution Approach 1:
The patent introduces a neutral-point wiring as an intermediary component that provides a dedicated current path between the first and second power storage units through the inverter and winding. This intermediary structure allows current to flow in a controlled manner, reducing electromagnetic interference and noise generation during switching operations while maintaining effective motor drive functionality.
Solution Approach 2:
The patent extracts the neutral-point wiring from the conventional inverter structure and houses it separately within the case. By taking out this specific component and providing it with dedicated housing and shielding, the patent isolates the noise-generating elements from the external environment, thereby reducing external noise transmission while preserving the driving function.
2Object-generated harmful factors
If neutral-point wiring is housed inside the case with shield function, then noise transmission is reduced, but device structure becomes more complex
Solution Approach 1:
The patent merges the neutral-point wiring housing with the existing inverter case structure. By integrating the shielding function into the case that already houses the inverter, the patent reduces structural complexity compared to adding a separate shielding structure. The case serves dual purposes: mechanical housing and electromagnetic shielding, thereby reducing noise transmission without significantly increasing device complexity.
3Reliability
If current flows between first and second power storage units through inverter, winding, and neutral-point wiring, then voltage equalization is achieved, but noise is generated during current flow
Solution Approach 1:
The patent applies local quality by providing specific shielding and housing only for the neutral-point wiring portion that is most susceptible to generating and transmitting noise. The case with shield function is strategically positioned to cover the neutral-point wiring, inverter, and winding assembly, creating a localized electromagnetic shield where it is most needed. This approach achieves noise reduction during voltage equalization current flow without requiring complete system redesign.
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 apparatus effectively reduces noise emitted outside by incorporating a shielded neutral-point wiring within the case, minimizing noise transmission to the body ground.
Implementation Method 1
a case that houses at least the inverter and provides a shield function
Data Source
AI summary
An inverter in a power conversion apparatus has a series connection body of upper- and lower-arm switches. The series connection body connects in parallel to a series connection body of first and second power storage units. A rotating electric machine has a winding that is electrically connected to the inverter. A neutral-point wiring electrically connects a negative electrode side of the first power storage unit and a positive electrode side of the second power storage unit, and a neutral point of the winding. A control unit performs switching control of the upper- and lower-arm switches such that a current flows between the first power storage unit and the second power storage unit through the inverter, the winding, and the neutral-point wiring. A case houses at least the inverter and provides a shield function. At least a portion of the neutral-point wiring is housed inside the case.