Wireless Charging Line Segmentation for High-Frequency EV Power Transfer
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Solution Overview
Problem
The existing wireless charging power supply systems for electric vehicles face challenges such as increased withstand voltage issues when frequency is raised from 20-40 kHz to 85 kHz, reduced charging time and amount, compatibility issues with different wireless charging pads, and high costs and electromagnetic interference (EMI).
Innovation Solution
The proposed system includes a power supply segment with a ferromagnetic core and a pick-up system with a capacitor for withstand voltage branching, which reduces the withstand voltage and improves compatibility with various wireless charging pads. The system also uses an inverter connected to multiple power supply segments for controlling the AC current and sharing power factor correction, and a pick-up system with a ferromagnetic core and a capacitor for reducing magnetic field density and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency is increased from 20-40 kHz to 85 kHz to reduce weight and size of wireless charging components, then the charging efficiency and speed are improved, but the withstand voltage between both ends in the power supply line increases by about 4.25 times causing discharge and leakage current problems
Solution Approach 1:
The power supply line is divided into multiple segments with individual capacitors connected to each segment. This segmentation allows the total withstand voltage to be distributed across multiple smaller voltage sections, preventing discharge and leakage current problems while maintaining high-frequency operation for efficient charging.
Solution Approach 2:
Capacitors are added to change the electrical parameters of the power supply line by providing voltage branching. This parameter change reduces the withstand voltage across each segment by distributing the voltage through capacitive coupling, enabling safe high-frequency operation.
2Reliability
If the length of the power supply line is shortened to suppress withstand voltage, then the discharge and leakage current problems are reduced, but the charging time of the electric vehicle while driving is shortened resulting in significantly reduced charging amount
Solution Approach 1:
The power supply line is segmented into multiple sections with capacitors at each segment. This allows the line to be extended in length while maintaining safe withstand voltage levels across each segment, thereby increasing the available charging time and charging amount without causing discharge or leakage current.
Solution Approach 2:
Capacitors are introduced as intermediary components between power supply segments. These capacitors act as voltage distributors that enable the power supply line to be longer while maintaining safe voltage levels across each segment, thus allowing extended charging time and increased charging amount.
3Ease of manufacture
If a single coil is wound in one turn in the vehicle travel direction to simplify the power supply line, then the installation is easier, but the compatibility with wireless charging pads attached to other vehicles is lacking
Solution Approach 1:
The power supply line is configured with multiple coils wound in different directions (one turn in vehicle travel direction, another turn perpendicular to it). This multi-directional coil arrangement provides universal compatibility with various wireless charging pad orientations while maintaining relatively simple installation through standardized winding patterns.
Solution Approach 2:
The coil configuration is extended from a single-dimensional (one-turn) arrangement to a two-dimensional arrangement with coils wound in multiple directions. This dimensional expansion enables compatibility with wireless charging pads attached to vehicles traveling in different directions or with different pad orientations.
4Productivity
If the frequency is increased to 85 kHz to reduce the weight and size of wireless charging components, then the charging speed is improved, but the cost of wireless charging becomes relatively higher compared to wired charging
Solution Approach 1:
Capacitors are added to change the electrical parameters of the power supply line, enabling high-frequency operation with reduced voltage stress. This parameter change allows the system to operate at 85 kHz for fast charging while managing the associated costs through efficient voltage distribution and reduced component stress.
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 system effectively reduces the withstand voltage of the power supply line, improves compatibility with various wireless charging pads, reduces electromagnetic interference (EMI), and extends the length of the power supply section, thereby enhancing the economic feasibility and efficiency of wireless charging.
Implementation Method 1
a power supply core composed of a ferromagnetic material for effectively transferring the power generated from the power supply cable to a pick-up system
Implementation Method 2
a pick-up system with a capacitor for withstand voltage branching, which reduces the withstand voltage
Implementation Method 3
a pick-up system with a ferromagnetic core and a capacitor for reducing magnetic field density and heat generation
Data Source
AI summary
A wireless charging power supply and pick-up system during operation of electric vehicles and industrial equipment while operating is described. The withstand voltage problem on the power supply line was solved by the capacitor provided in the inverter, and the power supply line and common line arrangement. This makes it possible to extend the wireless power supply line and the economical problem of the wireless charging system is greatly improved.In the prior art, compatibility was maintained with various wireless charging pick-up pads installed in the vehicle by using a plurality of inverters. In this system, compatibility is satisfied at a lower cost by utilizing the relay present in the inverter. The EMI of the power supply line is reduced by maximizing the magnetic field cancellation effect by using the structure of the common line and the shielding tube. In addition, it improves the limitation of the length of the power supply line section and the problem of the dead zone during wireless charging while driving.