Power Conversion Device Impedance Circuit Noise Reduction
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Solution Overview
Problem
Conventional power conversion devices generate switching noise that propagates to both the power-supply and load sides, leading to increased device scale when attempting to mitigate this noise.
Innovation Solution
The implementation of an impedance circuit in parallel with a reactor, featuring a larger electrostatic capacitance than parasitic capacitance, reduces impedance and cancels out noise by matching impedances between power feed buses, thereby reducing high-frequency noise without increasing device scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filter circuits are added to remove switching noise, then noise reduction is achieved, but device scale increases
Solution Approach 1:
The patent combines the noise filtering function with the existing reactor by connecting a capacitor in parallel with the reactor. This integration allows the reactor to serve dual purposes: its primary function in the power conversion circuit and its secondary function as a noise filter, thereby reducing device scale while achieving noise reduction
Solution Approach 2:
The reactor is designed to perform multiple functions simultaneously: power conversion and noise filtering. By adding the capacitor in parallel, the reactor becomes a multi-functional component that handles both the main power processing and the suppression of switching noise, eliminating the need for separate dedicated filter circuits
2Object-affected harmful factors
If multiple filter circuits are provided at preceding and subsequent stages, then noise removal is improved, but device complexity increases
Solution Approach 1:
The patent merges the noise filtering function into the existing reactor structure by adding a single capacitor in parallel. This single integrated solution replaces what would otherwise require multiple separate filter circuits at different stages, thereby reducing circuit complexity while maintaining effective noise suppression
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 reduces noise generated by switching without enlarging the device, by lowering impedance and canceling noise currents, and can set resonance frequencies to avoid interference with switching frequencies, thus minimizing high-frequency noise propagation.
Implementation Method 1
an impedance circuit 2 is provided in parallel with respect to the reactor L1... reduces impedance and cancels out noise by matching impedances between power feed buses
Implementation Method 2
featuring a larger electrostatic capacitance than parasitic capacitance... effectively reduces noise generated by switching
Implementation Method 3
can set resonance frequencies to avoid interference with switching frequencies, thus minimizing high-frequency noise propagation
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A power conversion device that converts power supplied by a first power feed bus (93) and a second power feed bus (94), includes: a reactor (LI) connected to the first power feed bus (93); and a power module (4) that converts power supplied between the first power feed bus (93) and the second power feed bus (94) by switching. The power module (4) includes a switching element (Q1). Further, the power conversion device includes an impedance circuit (2) arranged in parallel with respect to the reactor (L1) of the first power feed bus (93).