Filter Circuit Loop Minimization for Noise Reduction
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Solution Overview
Problem
The parasitic inductance of filter circuits in power conversion devices can increase, leading to degraded filter performance due to noise radiation and electromagnetic induction from eddy currents in the housing, which affects the noise reduction effectiveness.
Innovation Solution
The configuration includes a filter unit, a housing, and external terminals forming a loop with wirings, where the wiring is coupled close to the external terminal to minimize the loop area, thereby reducing parasitic inductance and electromagnetic induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the filter circuit is coupled to the power conversion device, then the noise reduction effect is improved, but the parasitic inductance increases and electromagnetic induction degrades the filter performance
Solution Approach 1:
The filter circuit is segmented into separate components (filter capacitor, external terminal, housing, and wirings) that are strategically positioned to minimize parasitic inductance. The wiring is divided into specific paths that reduce loop area, separating the capacitor connection from the housing connection to optimize electrical performance while maintaining noise reduction functionality.
Solution Approach 2:
The patent transitions from a planar circuit layout to a three-dimensional spatial arrangement where the wiring connects the filter capacitor to the housing through optimized paths. The external terminal extends through the housing to reduce the loop area, utilizing spatial dimensionality to minimize parasitic inductance while maintaining effective noise filtering.
2Ease of manufacture
If the wiring is extended away from the external terminal, then the filter circuit is easier to assemble, but the loop area increases and electromagnetic induction worsens
Solution Approach 1:
The wiring is pre-configured with connection positions determined in advance during the design phase. The wiring is positioned to connect to the housing at specific locations that minimize loop area, with the connection position predetermined to optimize both electromagnetic performance and assembly simplicity. This preliminary positioning eliminates the need for complex assembly adjustments while maintaining low parasitic inductance.
3Stability of the object's composition
If the filter capacitor is positioned far from the external terminal, then the filter circuit is more stable, but the parasitic inductance increases and noise coupling worsens
Solution Approach 1:
The filter capacitor and external terminal are merged into a closely integrated configuration where the capacitor is positioned immediately adjacent to the terminal. This merging minimizes the distance between components, reducing parasitic inductance and preventing noise coupling while maintaining circuit stability through the tight electrical connection and optimized current path.
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 effectively suppresses noise coupling from the circuit board to the filter unit, enhancing the noise reduction effect and securing the filter's performance.
Implementation Method 1
a filter unit with a filter capacitor, the external terminal, the housing, and wirings for couples these parts constitute a loop
Implementation Method 2
the parasitic inductance of the filter circuit might increase and the noise radiated from a power conversion circuit and propagating in space and/or the electromagnetic noise caused by an eddy current flowing in a housing might be superimposed on the filter circuit, so that the electromagnetic induction might degrade the filter performance
Implementation Method 3
the electromagnetic noise caused by an eddy current flowing in a housing might be superimposed on the filter circuit
Data Source
AI summary
Provided is an electronic device that is provided with a filter circuit that suppresses the effects of electromagnetic noise propagated through space from a circuit board and reduces parasitic inductance, and can output a voltage with adequately reduced noise. To solve the above problem, in an electronic device provided with a cabinet (101), a circuit board (132) provided in the cabinet, an output terminal (122) that passes through a through hole provided in the cabinet and outputs the output of the circuit board to the outside, the present invention constructs a loop composed of a filter means (142) having a filter capacitor (142a), an output terminal, a cabinet, and wires (142b, 142c) for connecting these parts. The wire (142c) connected to the cabinet is connected to a position close to the output terminal, and reduces the size of the loop. In addition, a shield (102) is provided between the filter means and the circuit board.