Wireless power transfer system with foreign objects detection and large tolerances for electric vehicles by reactance change and triangular coils = 리액턴스 기반 이물질 감지 기능 및 삼각형 코일에 의한 넓은 허용 편차 특성을 가지는 무선충전 전기자동차 시스템

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This paper deals with a foreign object detection system (Chapters 1 ~ 3) applicable to electric vehicles (EVs) wireless charging system and a wireless EVs charger (Chapter 4) with large tolerance characteristics. In chapter 1, dual-purpose non-overlapping coil sets for both MOD and DoP, which detect a variation of magnetic flux on the power supply coil, are newly proposed. A sensing circuit, which has a variable resistor that is different from the conventional overlapping coil for MOD, can make the induced voltage difference zero even when the magnetic flux distribution is distorted by moving the pick-up coil. When metallic coins and aluminum sheets are located on the power supply coil, the induced voltage difference of the coil sets, which is ideally zero without metal objects, significantly increases to 62.8 mV and 450mV, respectively, which is more than 10 times the value without metal objects throughout experiments. In addition, when the pick-up coil approaches the power supply coil, induced voltage of each coil set increased roughly 1.6 times at 10 cm air-gap. In chapter 2, a metal object detection (MOD) system, a kind of foreign object detection (FOD), which is based on mistuned resonant circuits and utilizes variation of self-inductance of a sensing pattern, is newly proposed for wireless electric vehicle (EV) chargers. The sensing pattern that consists of multiple loop coil sets is mounted on the transmitting (Tx) pad of an EV charger, where a loop coil set has two coils connected in series with opposite polarity to cancel out the induced voltage generated by the Tx coil. To increase the detection sensitivity of the proposed MOD system, instead of an exact resonant frequency, a mistuned operating frequency near the -3dB point is utilized for the parallel-resonant circuit. In this way, the proposed MOD system can detect very small metal objects regardless of their position and orientation on the Tx coil without any blind zone. A prototype MOD system, operating at 85 kHz to satisfy the standard J2954, was fabricated to verify its feasibility. The results showed that output voltage change of the proposed MOD system becomes 22.7 %for a piece of aluminum foil of $3 x 3 cm^2$ and 40.9 %for 100 Korean Won coin, respectively. In chapter 4, A new set of triangular DQ transmitting (Tx) coils for wireless EV chargers is proposed for large longitudinal, lateral, and diagonal lateral tolerances. The coil set consists of two layers, i.e., D-Tx and Q-Tx, where each Tx layer has two triangular coils of the same magnetic polarity diagonally facing each other to generate a more uniform coupling coefficient between Tx and Rx with respect to misalignments. A prototype of an inductive power transfer (IPT) system using the proposed triangular DQ Tx coils for wireless EV chargers was fabricated for experimental verification with an operating frequency of 85 kHz satisfying the standard J2954 of the society of automotive engineers (SAE). From simulation and experimental results, it is found that the lateral and diagonal displacements of the proposed coil sets increase by 35 % and 19 %, respectively, at an air gap of 150 mm, compared with a conventional rectangular coil.
Rim, Chuntaekresearcher임춘택researcherCho, Gyuseongresearcher조규성researcher
한국과학기술원 :원자력및양자공학과,
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학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2018.2,[iiii, 64 p. :]


Metal object detection (MOD)▼aliving object detection (LOD)▼aforeign object detection (FOD)▼awireless EV charger▼alarge tolerance; 금속 감지 시스템▼a생명체 감지 시스템▼a이물질 감지 시스템▼a전기자동차 무선충전▼a넓은 허용 편차

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