AC-DC Converter Choke Configuration for EMI Suppression
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Solution Overview
Problem
Existing AC-DC power conversion solutions, such as those described in patent US20120032651A1, face issues with differential-mode current suppression and parasitic capacitance leading to EMI performance deterioration and increased losses.
Innovation Solution
The proposed solution involves using a combination of a first common-mode choke and a differential-mode choke, where the common-mode choke provides high inductance for common-mode currents and the differential-mode choke suppresses differential-mode currents, with the leakage inductance and capacitance of the common-mode choke assisting in reducing current ripples and spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an autotransformer is used to suppress differential-mode current, then current ripple suppression is improved, but parasitic capacitance causes spikes in leg current and deteriorates EMI performance
Solution Approach 1:
The single autotransformer is segmented into two separate transformers: a common-mode transformer and a differential-mode transformer. Each transformer is dedicated to suppressing a specific type of current ripple, preventing the EMI deterioration caused by parasitic capacitance in a single integrated autotransformer while maintaining effective current ripple suppression for both common-mode and differential-mode currents.
2Object-generated harmful factors
If separate common-mode and differential-mode inductors are used, then both types of current suppression are achieved, but device complexity and inductor size increase
Solution Approach 1:
The common-mode transformer and differential-mode transformer are merged into a single integrated transformer structure with coupled windings. This integration allows both common-mode and differential-mode current suppression functions to be achieved within a single compact component, reducing device complexity and minimizing the overall inductor size while maintaining effective suppression of both types of current ripples.
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 filters common-mode currents, reduces differential-mode current ripples, and improves EMI performance by providing twice the inductance of separate inductor designs, while minimizing the size of inductors required for a given current ripple requirement.
Implementation Method 1
The first common-mode choke can help provide high inductance to the high-frequency components of the common-mode current, which flows from the AC power source
Implementation Method 2
the first differential-mode choke suppresses differential-mode currents
Implementation Method 3
The leakage inductance and capacitance of the common-mode choke can help reduce the undesired differential-mode current ripple and spikes
Data Source
AI summary
An apparatus for conversion between AC power and DC power. The apparatus includes: a first power conversion circuit having a first AC side and a DC side, at least one second power conversion circuit each having a second AC side and sharing the DC side with the first power conversion circuit, and at least one choke having a first terminal, a second terminal and at least one third terminal, wherein: the first terminal is arranged to be electrically coupled to a phase of the AC power, and the second terminal and the at least one third terminal are electrically coupled to respective same phases of the first AC side of the first power conversion circuit and the second AC side of the at least one second power conversion circuit. Moreover, the choke includes: a first common-mode choke and a first differential-mode choke, wherein: the first common-mode choke and the first differential-mode choke are electrically coupled in series via a first group of coil ends of the first common-mode choke and a first group of coil ends of the first differential-mode choke, and a second group of coil ends of one of the first common-mode choke and the first differential-mode choke are electrically coupled to the first terminal of the choke, and a second group of coil ends of the other are respectively electrically coupled to the second terminal and the at least one third terminal of the choke. The first common-mode choke can help provide high inductance to the high-frequency components of the common-mode current, which flows from the AC power source, since the impedance of the common-mode choke and the differential-mode choke depends on frequency on the same scale as inductance. The advantages of using the common-mode choke is that it provides twice the inductance of separate inductor design due to the coupling effect. Therefore it filters the common-mode current more effectively on the inductance size can be reduced for a given current ripple requirement.