Electric Vehicle Power Supply Device EMI Noise Reduction
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Solution Overview
Problem
Electric vehicle power supply devices face challenges in providing stable voltage and reducing electromagnetic interference (EMI) noise during battery charging, while also enabling current sensing to confirm connection between electric vehicle charging facilities and vehicles, and achieving a two-point ground configuration with insulated PE and chassis grounds.
Innovation Solution
A power supply device incorporating a common mode filter unit with capacitors and a differential mode filter unit with an inductor, along with a second converter and specific capacitor placements to reduce EMI noise, and a two-point ground configuration with PE and chassis grounds to release noise to the chassis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a power supply device is used to supply stable voltage to electric vehicle components, then voltage stability is improved, but electro-magnetic interference (EMI) noise increases
Solution Approach 1:
A common mode filter unit is introduced as an intermediary component between the power supply device and the electric vehicle components. This filter unit includes a common mode choke and capacitors that selectively filter out EMI noise while allowing stable voltage transmission, thus resolving the contradiction between voltage stability and EMI reduction
Solution Approach 2:
The harmful EMI noise is extracted and separated from the stable voltage signal using the common mode filter unit. The filter removes the high-frequency noise components while preserving the useful low-frequency voltage signal, enabling both voltage stability and EMI reduction
2Difficulty of detecting and measuring
If current sensing is enabled to confirm connection between charging facility and electric vehicle, then connection detection capability is improved, but device complexity increases
Solution Approach 1:
The existing power supply device is designed to perform multiple functions: it supplies stable voltage to components and simultaneously enables current sensing for connection detection. By integrating these functions into a single device, the need for separate connection detection equipment is eliminated, thus improving detection capability without proportionally increasing complexity
Solution Approach 2:
The power supply device performs self-diagnosis by monitoring its own current output to detect connection status. The device uses its existing current sensing capabilities to determine whether the charging facility is properly connected, eliminating the need for additional dedicated detection hardware
3Object-generated harmful factors
If a two-point ground configuration with insulated PE and chassis grounds is implemented, then EMI noise reduction is improved, but manufacturing complexity increases
Solution Approach 1:
The ground system is segmented into two distinct ground points: a PE (protective earth) ground and a chassis ground, which are electrically insulated from each other. This segmentation allows different ground functions to be performed separately, improving EMI noise reduction while maintaining manufacturability through clear design specifications
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
The solution provides stable voltage to electric vehicle components, enables effective current sensing, and significantly reduces EMI noise, ensuring reliable operation and connection confirmation between electric vehicles and charging facilities.
Implementation Method 1
a common mode (CM) filter unit having a first capacitor and a second capacitor
Implementation Method 2
a differential mode (DM) filter unit having an inductor and a third capacitor
Implementation Method 3
one end of the first capacitor is connected to a positive (+) terminal of a battery and the other end is connected with a potential earth (PE) ground
Implementation Method 4
a differential mode (DM) filter unit having an inductor and a third capacitor
Data Source
AI summary
The present invention relates to a power supply device for supplying power, from a battery provided at an electric vehicle, to various types of components, the power supply device enabling current sensing to be performed so as to confirm that an electric vehicle charging facility and an electric vehicle are connected to each other through a connector, and reducing electro-magnetic interference (EMI) noise. The objective of the power supply device of the present invention is to: provide a stable voltage to electric vehicle application components; and reduce the EMI noise according to battery charging, self-switching of the power supply device and the like.