Wireless Charging Coil Turn Control for EV Misalignment
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Solution Overview
Problem
Wireless power transfer (WPT) systems for electric vehicles (EVs) face efficiency issues due to misalignment and differences in coil shapes between the transmission and reception pads, leading to reduced voltage and current transfer and overall efficiency.
Innovation Solution
A method and apparatus that control the number of turns in the transmission and reception coils based on detected alignment states and coil shapes to optimize the turn ratio, using switches to adjust the coil configuration and maintain resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission pad and reception pad are misaligned, then the coupling coefficient decreases and leakage inductance increases, but the magnetization inductance fluctuates causing resonance failure and reduced voltage/current transfer
Solution Approach 1:
The patent changes the physical parameter of coil turns in real-time based on detected alignment states. When misalignment is detected, the system adjusts the number of turns in either the transmission coil or reception coil to compensate for the changed coupling conditions, thereby maintaining resonance stability and power transfer efficiency despite alignment variations
2Adaptability or versatility
If coils of different shapes are used for transmission and reception pads, then design flexibility increases, but voltage and current transfer decrease and efficiency is reduced
Solution Approach 1:
The patent uses parameter changes (adjusting coil turns) to compensate for the inherent inefficiencies caused by using coils of different shapes. By dynamically adjusting the number of turns based on the actual alignment and shape mismatch conditions, the system maintains high power transfer efficiency while preserving the design flexibility to use different coil geometries for transmission and reception pads
3Loss of energy
If the number of turns in coils is increased to compensate for misalignment, then coupling coefficient improves, but device complexity and control difficulty increase
Solution Approach 1:
The patent implements a dynamic control system where the number of coil turns is adjusted in real-time based on detected alignment states. Switches are used to dynamically reconfigure the coil connections, allowing the system to adapt to changing alignment conditions while maintaining relatively simple hardware architecture. The control system monitors alignment and automatically adjusts coil configuration without requiring complex manual intervention
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 approach enhances the efficiency of wireless power transfer by compensating for misalignment and coil shape differences, ensuring stable output voltage and current transfer.
Implementation Method 1
a reception coil in a vehicle assembly (VA) mounted in the EV forms an inductive resonant coupling with a transmission coil in a group assembly (GA) located in a charging station or a charging spot. Electric power is then transferred from the GA to the VA to charge the high-voltage battery of the EV through the inductive resonant coupling.
Implementation Method 2
Since a leakage inductance Llk is relatively large as compared with a magnetization inductance Lm, it is difficult to transfer electric power to the output. Therefore, at least one capacitor is implemented in a primary pad and a secondary pad, i.e., the transmission pad and the reception pad, respectively, to resonate inductance of the primary and secondary pads and the at least one capacitor.
Data Source
AI summary
A method for wireless power transfer (WPT) to an electric vehicle (EV) performed by a wireless charging apparatus may include detecting, by the wireless charging apparatus, an alignment state between a transmission pad mounted in the wireless charging apparatus and a reception pad mounted in the EV; controlling, by the wireless charging apparatus, a number of turns in a transmission coil included in the transmission pad or a reception coil included in the reception pad according to the detected alignment state; and performing, by the wireless charging apparatus, WPT to the EV after the controlling of the number of turns in the transmission coil or the reception coil is completed.