Pi-Type Noise Filter Partitions for RF Noise Reduction
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Solution Overview
Problem
Existing power conversion devices in hybrid and electric automobiles face challenges in achieving improved radio frequency noise reduction performance while meeting demands for smaller size and lower cost, as current technologies either fail to enhance noise reduction or require additional components.
Innovation Solution
A π-type noise filter with first and second ground points and partitions in a metal case, incorporating a magnetic core, capacitors, and strategically placed partitions to enhance noise reduction performance, while maintaining a compact design without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional switches and capacitors are added to the noise filter as in PTL 1, then radio frequency noise reduction performance is improved, but device size and cost increase
Solution Approach 1:
The patent extracts and utilizes the parasitic capacitance that naturally exists between the insulation board and ground, eliminating the need for additional dedicated capacitors. This approach maintains noise reduction performance while reducing device complexity by repurposing an existing parasitic element into a functional component.
Solution Approach 2:
The patent converts the harmful parasitic capacitance between the insulation board and ground into a beneficial filtering element. By intentionally utilizing this previously unwanted capacitance for noise reduction, the design achieves improved radio frequency noise performance without adding extra components, thereby reducing device size and cost.
2Device complexity
If the noise filter is designed without additional components as in PTL 2, then device size and cost are reduced, but radio frequency noise reduction performance is not significantly improved
Solution Approach 1:
The patent changes the electrical parameters of existing components by strategically positioning the insulation board to create a specific parasitic capacitance value. By adjusting the physical parameters (distance to ground, board area) of existing structures, the design achieves effective noise reduction without adding components, thus maintaining low device complexity while improving noise performance.
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 proposed filter device and power conversion device achieve enhanced radio frequency noise reduction performance, meeting the demand for smaller size and lower cost by optimizing the filter's structure to maximize noise reduction without increasing size or cost.
Implementation Method 1
a magnetic core configured to surround a direct current wiring including a positive electrode wiring and a negative electrode wiring
Implementation Method 2
a first capacitor disposed in a stage preceding the magnetic core and connected to the direct current wiring; and a second capacitor disposed in a stage subsequent to the magnetic core and connected to the direct current wiring
Data Source
AI summary
Provided is a filter device including a π-type noise filter, and a metal case in which a first ground point and a second ground point are formed. The π-type noise filter includes a magnetic core configured to surround a direct current wiring, a first capacitor disposed in a stage preceding the magnetic core, a second capacitor disposed in a stage subsequent to the magnetic core, each of the first capacitor and the second capacitor connected to a corresponding one of the first ground point and the second ground point. A first partition and a second partition opposing each other are formed between the first ground point and the second ground point, and the first partition and the second partition have a predetermined gap between each other. Provided is a power conversion device including the filter device and a power conversion unit.