Power Converter Input Capacitor Layout for Radiation Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for reducing radiation noise in power conversion devices are inadequate, particularly due to the induction of high-frequency noise components from paths with larger noise levels to paths with smaller noise levels, leading to increased radiation noise.
Innovation Solution
Incorporating a noise reducing capacitor in the path connecting the rectifier circuit and the smoothing capacitor, and optionally another across-the-line capacitor between the smoothing capacitor and the inverter circuit, to bypass high-frequency noise components and reduce radiation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional noise reduction methods are used, then some noise attenuation is achieved, but radiation noise remains high due to induction from adjacent high-noise paths
Solution Approach 1:
A common mode choke is introduced as an intermediary component in the input side circuit to block the induction path. The choke's magnetic core creates a high impedance path for common mode noise currents, preventing noise from adjacent high-noise paths from coupling into low-noise paths. This mediator effectively isolates different noise zones without requiring changes to the power conversion circuit itself.
Solution Approach 2:
The noise reduction function is extracted from the power conversion circuit and placed in a separate input side circuit. By positioning the common mode choke and capacitor in the input circuit rather than within the switching circuit, the invention separates the noise generation source from the noise reduction mechanism, allowing independent optimization of both functions.
2Ease of manufacture
If paths with large noise components are placed adjacent to paths with small noise components, then circuit layout is simplified, but noise induction increases radiation noise
Solution Approach 1:
The common mode choke acts as a physical and electromagnetic barrier between adjacent circuit paths. Even when high-noise and low-noise paths are placed adjacent for manufacturing simplicity, the choke's magnetic shielding effect prevents harmful induction, allowing flexible layout without compromising noise performance.
Solution Approach 2:
The invention accepts the presence of adjacent high-noise paths as a given condition and converts the potential harm into a manageable issue by using the common mode choke to contain and redirect noise currents. The noise is not eliminated at the source but is instead channeled through controlled paths to ground, transforming an uncontrolled radiation problem into a managed current flow.
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
Effectively reduces radiation noise by minimizing the induction of high-frequency noise components, thereby decreasing the overall radiation noise emitted by the power conversion device.
Implementation Method 1
a first across-the-line capacitor provided in a path connecting the positive line and the negative line between the rectifier circuit and the smoothing capacitor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A technique capable of more appropriately reducing the radiation noise of a power conversion device is provided. A power conversion device 1 according to an embodiment of the present disclosure includes a rectifier circuit 10 that is adapted to convert AC power input from a commercial AC power supply PS into DC power, a smoothing capacitor Cdc provided in a path connecting a positive line PL and a negative line NL of DC power output from the rectifier circuit 10, an inverter circuit 30, connected to the positive line PL and the negative line NL in parallel with the smoothing capacitor Cdc, wherein the power conversion circuit (30) is adapted to convert DC power smoothed by the smoothing capacitor Cdc into predetermined AC power by switching operation of semiconductor elements S1 to S6 and to output the predetermined AC power, and a noise reducing capacitor C1 provided in a path connecting the positive line PL and the negative line NL between the rectifier circuit 10 and the smoothing capacitor Cdc.