Power Converter High Frequency Noise Reduction via Segmented Inductors
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Solution Overview
Problem
Conventional power converters experience inadequate noise reduction in high-frequency regions due to the limitations of conventional common mode choke coils, which are ineffective in reducing noise beyond the switching frequency and harmonic wave frequencies.
Innovation Solution
The implementation of a power converter with a three-phase common mode choke coil configuration, where inductors are connected between external terminals and nodes, and an additional inductor is connected between the ground conductor and earth terminal, enhancing noise reduction in high-frequency regions by intensifying magnetic fluxes and canceling out noise currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional common mode choke coil is used, then noise in low frequency region (switching frequency) is reduced, but noise in high frequency region (ringing frequency) is not sufficiently reduced
Solution Approach 1:
The common mode choke coil is divided into multiple independent inductors (first inductor, second inductor, third inductor) connected in parallel between different external terminals and the earth terminal. This segmentation allows each inductor to be optimized for specific frequency ranges, with the combination providing broad-spectrum noise reduction from low frequency switching noise to high frequency ringing noise.
Solution Approach 2:
Different inductors are designed with different inductance values to target different frequency ranges. The first inductor has a different inductance value than the second and third inductors, allowing the system to effectively suppress noise across a wide frequency spectrum by changing the electrical parameters of the inductive elements.
2Ease of operation
If inductors are connected only between external terminals and nodes, then power conversion function is maintained, but common mode noise leaking to power system is not sufficiently reduced
Solution Approach 1:
The earth terminal acts as an intermediary connection point where multiple inductors converge. This intermediary structure provides a dedicated path for common mode noise currents to flow to ground through the inductive impedance, separating the noise suppression function from the power conversion function and enabling effective noise reduction without affecting normal operation.
3Object-affected harmful factors
If a three-phase common mode choke coil configuration is implemented, then noise reduction in high frequency region is enhanced, but device complexity increases
Solution Approach 1:
Multiple inductors are merged into a single common mode choke coil assembly where the first, second, and third inductors are inductively coupled to form a three-phase common mode choke coil. This merging approach provides the noise reduction benefits of multiple inductors while presenting a unified, manageable component structure that simplifies installation and maintenance.
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 significantly reduces common mode noise in high-frequency regions, effectively minimizing leakage current and high-frequency noise propagation to the ground and power system, as demonstrated by noise level measurements showing decreased noise levels at frequencies such as 1.2 MHz and 25 MHz compared to conventional examples.
Implementation Method 1
a plurality of inductors, each of the plurality of inductors being inserted between a corresponding one of the plurality of external terminals and a corresponding one of the plurality of nodes; and another inductor inserted between the ground conductor and the earth terminal
Implementation Method 2
enhancing noise reduction in high-frequency regions by intensifying magnetic fluxes and canceling out noise currents
Implementation Method 3
The fluctuation of the common mode voltage causes leakage current flowing to a ground (earth)... By connecting the inductors to not only the external terminals but also the earth terminal, a noise reduction effect in a high frequency region can be increased
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A power converter includes: a plurality of external terminals; a grounded earth terminal; a power conversion circuit; a ground conductor; and a plurality of inductors. A plurality of nodes of the power conversion circuit are connected to the respective plurality of external terminals. The power conversion circuit performs power conversion by switching received power. A plurality of inductors are inserted between the plurality of external terminals and the plurality of nodes. Further, an other inductor is inserted between the ground conductor and the earth terminal. In this way, there can be provided a power converter that provides a sufficient noise reduction effect also in a high frequency region.