The inductive power transfer (IPT) has contributed to the fast growth of the electric vehicle (EV) market. The technology to recharge the EV battery has attracted the attention of many researchers and car manufacturers in developing green transportation. In IPT charging system, the coil design is indispensable in enhancing the EV battery charging process performance. This paper starts by describing the two charging techniques; static charging and dynamic charging before further presents the IPT system descriptions. Afterwards, this paper describes a brief review of coil designs which discusses the critical factors that affect the power transmission efficiency (PTE) including their basic designs, design concepts and features merits. The discussions on the basic coil designs for IPT are of the circular spiral coil (CSC), square coil (SC), rectangular coil (RC), and double-D coil (DDC). Furthermore, the significant advantages and limitations of each research on different geometries are analyzed and discussed in this paper. Finally, this paper evaluates some essential aspects that influence the coil geometry designs in practical.

Electric vehicles (EV) have been introduced in the recent years due to public awareness of the effect of gas emission from traditional cars and the extinction of petroleum natural resources. For charging EV, dynamic wireless charging is considered in this paper. This is because it is more convenient and saves charging time since it charges the electric vehicle while moving. The main challenge of this process is to maintain a high amount of power transfer from primary to secondary coil. One of the factors contributing to a good power transfer is the size of the coil [1]. There are various designs of coil for wireless charging of electric vehicles (EV). Among the most common designs are circular pad (CP), rectangular pad (RP), double-D pad (DDP), and double-D quadrature pad (DDQP). In this paper, circular pad (CP) is chosen for use, due to its simplicity in design and good electrical and magnetic properties. Three different coil pair sizes are tested to find the most suitable coil pair for the primary and secondary pads that has the maximum power transfer and is least sensitive to misalignment. The magnetic properties have been investigated to obtain the highest value of magnetic flux. The geometry design of the pads and simulation was done using COMSOL Multiphysics software. From the simulation, it was found that the unsymmetrical coil pair gives high magnetic strength when the outer diameters of the primary and secondary coils have the same value. ABSTRAK: Kenderaan Elektrik (EV) telah diperkenalkan sejak beberapa tahun ini hasil kesedaran awam tentang kesan pembebasan gas dari kenderaan lama dan pengurangan sumber asli petroleum. Kajian ini berkaitan pengecas dinamik tanpa wayar bagi mengecas EV. Ini kerana pengecas ini lebih sesuai dan jimat masa mengecas kerana kenderaan elektrik dicas ketika bergerak. Cabaran utama proses ini adalah mengekalkan pemindahan tenaga yang tinggi daripada gegelung primer kepada gegelung sekunder. Salah satu faktor bagi mendapatkan pemindahan tenaga yang tinggi adalah saiz gegelung wayar [1]. Terdapat pelbagai bentuk gegelung bagi mengecas kenderaan elektrik (EV) tanpa wayar. Antaranya adalah pad membulat (CP), pad segiempat tepat (RP), pad berganda-D (DDP), dan pad kuadratur berganda-D (DDQP). Kajian ini telah menggunakan pad membulat (CP) kerana reka bentuknya yang ringkas dan ia mempunyai sifat elektrikal dan magnatik yang baik. Tiga pasang gegelung berbeza telah diuji bagi mendapatkan pasangan gegelung pad primer dan sekunder yang paling sesuai di mana ianya mempunyai pemindahan tenaga maksima dan paling kurang sensitif pada ketidakjajaran. Sifat magnet telah diuji bagi mendapatkan nilai fluks magnet tertinggi. Rekabentuk geometri pad dan simulasi telah dijalankan menggunakan perisian Multifizik COMSOL. Hasil simulasi mendapati pasangan gegelung yang tidak simetri telah menghasilkan kekuatan magnetik tertinggi apabila diameter luaran gegelung primer dan sekunder mempunyai nilai sama.

Electric vehicles (EV) have gained worldwide attention since the implementation of a wireless power transfer (WPT) to charge their batteries. With WPT, it can be very convenient for EV to be charged dynamically. Nevertheless, there are some issues in dynamic WPT, such as maintaining the power transfer efficiency. Several factors that lead to these problems include disruption of the alignment and the optimum distance between the transmitter and receiver coils. It is thus contributing to the loss of power efficiency when charging the EV. Not to mention, manufacturers build different specifications of EV charging station for different types of EV models in order to meet customer demands. An incompatible charging device will not utilize EV wireless charging to its maximum potential. Hence, to improve the power output capability as well as stabilizing the maximum power transfer during the charging process, a compensation circuit is added to the system. This article focuses on comparing two available compensation circuits (series-series (SS) topology and series-parallel (SP) topology) under the application of dynamic wireless charging. The simulations are conducted using NI Multisim based on the relationship of power transfer efficiency with resonance frequency, coefficient of coupling, and the load resistance. The WPT efficiency for SP-topology shows that it is sensitive to the change of resonance frequency and coupling coefficient, whereas SS-topology maintains good efficiency during the WPT process. Nonetheless, SS-topology performance suffers efficiency loss when paired with a higher load, while SP-topology acts differently. This article will observe the best conditions on the selected compensation designs for better application in EV charging systems in a moving state. ABSTRAK: Kenderaan elektrik (EV) telah menarik perhatian dunia sejak pelaksanaan alih kuasa wayarles (WPT) bagi mengecas bateri. Melalui WPT, EV lebih mudah kerana ia boleh dicas secara dinamik. Namun, pengecasan dinamik WPT turut mengalami masalah, seperti mengimbang kecekapan pemindahan kuasa. Beberapa faktor yang membawa kepada masalah ini adalah kerana terdapat gangguan penjajaran dan jarak optimum antara gegelung pemancar dan penerima. Kerana ini, ia menyumbang kepada kehilangan kecekapan kuasa semasa mengecas EV. Pengeluar juga membina spesifikasi stesen pengisian EV berlainan mengikut jenis model EV demi memenuhi permintaan pelanggan. Namun, platform pengecas EV yang berbeza, tidak dapat mengecas EV secara wayarles dengan maksimum. Oleh itu, bagi membaiki keupayaan jana kuasa serta menstabilkan pengeluaran kuasa maksimum semasa proses pengecasan, litar gantian ditambah ke dalam sistem. Artikel ini memberi keutamaan pada dua litar gantian berbeza (topologi bersiri (SS) dan siri-selari (SP)) di bawah aplikasi pengecasan wayarles dinamik. Simulasi dibuat menggunakan NI Multisim mengikut kecekapan pemindahan kuasa dengan frekuensi resonan, pekali gandingan dan rintangan beban. Kecekapan WPT bagi topologi-SP menunjukkan ianya sensitif pada perubahan frekuensi resonan dan pekali gandingan. Manakala topologi-SS kekal cekap semasa proses WPT. Walau bagaimanapun, prestasi topologi-SS berkurangan ketika diganding dengan beban besar, begitu juga berbeza bagi topologi-SP. Artikel ini akan mengkaji keadaan terbaik pada reka bentuk gantian terpilih bagi aplikasi EV dalam sistem pengecasan bergerak.

As the population grows, people will consume more natural resources. This issue will lead to a low petrol supply for all land transportation, especially supplies for car consumption. Therefore, the electric vehicle (EV) has been introduced to overcome this issue. Currently, wired charging of EVs has been implemented in most of the developed country, including Malaysia. However, some drawbacks have been found from this technology. Therefore, wireless charging comes into the picture to solve this issue. Charging pad on the road and at the car are required for both wired and wireless charging. Various designs of charging pad are available. However, this paper will only focus on the circular design. There is many software that can be used to design the coil pad. Each software has a different procedure and steps to design the coil pad. In this paper, JMAG Designer software will be used to design the circular coil pad. Then, three coil pair were simulated using JMAG Designer to investigate the magnetic flux density between primary and secondary coil when varying the misalignment of 0 cm, 4 cm and 8 cm. From the simulation, there is no specific trend in the relationship between magnetic flux density and misalignment.

This paper presents a new design of circular coil for both primary and secondary sides in wireless power transfer (WPT). This paper starts with the numerical solution of 500W power for ideal case WPT to calculate the values of coil parameters for both primary and secondary sides. The optimum value of coupling coefficient (k) was verified by k < kc where kc is the critical coupling coefficient. After that, this paper designs the schematic circuit of this project by using all component values from the previous step. The circuit is then simulated by using NI Multisims software to obtain the measured values of the coil parameters. Next, this paper discusses the power efficiency between calculated and measured values. Finally, the summary of the suitable dimensions for inner and outer diameters and the number of turns needed for both primary and secondary coils are calculated by using the values of inductance. © 2021 IEEE.