Indonesian Journal of Electrical Engineering and Computer Science Vol. 20, No. 3, December 2020, pp. 1703~ 1716 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v20.i3.pp1703-1716  1703 Journal homepage: http://ijeecs.iaescore.com A brief review: basic coil designs for inductive power transfer Nadia Nazieha Nanda 1 , Siti Hajar Yusoff 2 , Siti Fauziah Toha 3 , Nurul Fadzlin Hasbullah 4 , Amelia Shafina Roszaidie 5 1,2,4,5 Department of Electrical and Computer Engineering, International Islamic University, Malaysia 3 Department of Mechatronics Engineering, International Islamic University, Malaysia Article Info ABSTRACT Article history: Received Apr 1, 2020 Revised Jun 21, 2020 Accepted Jul 20, 2020 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. Keywords: basic coil designs dynamic wireless charging (DWC) electric vehicle (EV) inductive power transfer (IPT) power transfer efficiency (PTE) static wireless charging (SWC) wireless power transfer (WPT) Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Nadia Nazieha Nanda, Department of Electrical and Computer Engineering, International Islamic University Malaysia, Jalan Gombak, 53100 Kuala Lumpur, Malaysia. Email: nnazieha.nanda@gmail.com 1. INTRODUCTION Wireless power transfer (WPT) system is using the power transmission coil principle to transfer the electric power from the primary grid source to energize the electric vehicle (EV) [1]. The implementation of the WPT system to the EV has hugely evolved after the issue related to the depletion of energy resources especially petroleum started to get global attention besides the fact that petroleum gas emission has contributed to air pollution [2]. Fortunately, this arising issue is supported by the willingness of car manufacturers to be involved in this technology. There are different approaches to WPT, such as the capacitive coupling, inductive coupling, and magnetic-resonance coupling [3]. Capacitive coupling relies on the coupling of two plates that produce the electric field. The alternating voltage of transmitter plate will create the electrostatic field on the receiver plate causes by the induced EMF from the oscillating electric field [4]. The capacitive coupling can be used only for low power applications, such as drone charging or mobile charging, and this approach is obviously less suitable for charging the EV [5, 6]. However, this approach might be able to be implemented for EV if a proper design of a compensation network is utilized [7]. Meanwhile, in IPT, the field created from the coupling of the two coils; transmitter (primary) coil and receiver (secondary) coil, is referred to as the magnetic field. The magnetic field produced results from obeying the Ampere's Law and Faraday's Law [8]. The source generates an alternating current that creates an oscillating magnetic field at the transmitter coil. The magnetic field produced is then passed through to the receiver coil and thus produced the induced alternating current to flow in the load of the circuit, which commonly is the EV's battery. For the magnetic-resonance coupling, it uses the resonant principle where it allowed the coupling