Abstract Car suspension system play important role to determine the comfort of car subject to the road profile. For mechanical car suspension system, to improve the suspension, the spring and hydraulic damper are elements that need to be studied. In this research, we change the spring in the suspension system with an electromagnetic suspension. To study the efect of electromagnetic suspension, a simple mathematical model of electromagnetic car suspension is formulated. The model is solved using analytical method. The analysis of the solution of the model are presented and interpreted. Electromagnetics Car Suspension System Ahmad Zaki Mohamad Amin * , Shamsuddin Ahmad and Yeak Su Hoe Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia; azmamin87@gmail.com, shamsuddina@utm.my, s.h.yeak@utm.my Keywords: Car Suspension, Electromagnetics, Repulsive Force 1. Introduction Automotive industry is one of the major revenue in Malaysia. Of course the industry need to produce a good car especially in term of comfort and safety. To produce the comfortable car, its suspension systems must be able to absorb road irregularities rapidly and could return to its normal position gradually while maintaining optimal tire to road contact 1–3 . In the passive suspension system, there is very hard to determine suitable sof spring or hard spring to keep the passenger comfort due to road irregularities. In this study the spring in the passive suspension system is change with electromagnetic suspension shown in Figure 1. Te two magnetic bars with the same poles produced repulsive forces in between the gap of movable magnet and electromagnet. Tese forces will compensate the vibration between the road and the car body. In order to investigate the dynamic behavior of the suspension system, a quarter car model is formulated even though the full car model is preferred 4 . Tis quarter car model for passive system is simple and consists of one fourth of the body mass, suspension components and one wheel. 2. Magnetic Repulsive Force Te magnetic co-energy W 5 given as 2 1 2 W Li = (1) Where, the inductance L is given by 6 as z A N L 2 0 m = (2) and ) (t i is current. In the Equation (2), 0 m is permeability of free space, N is the number of turns, A is the cross sectional area and z is the gap between two magnetic bars with the same poles. Te electromagnetic force F is defned as the rate of change of co-energy 6 . constant ) , ( ) , ( = ∂ ∂ = i z z i W z i F (3) By substituting the Equation (1) and Equation (2) into the Equation (3), fnally we have 2 2 0 2 (, ) 4 N Ai Fiz z m =− . (4) Note that the minus sign means the force is a repulsive force. *Author for correspondence Indian Journal of Science and Technology, Vol 9(40), DOI: 10.17485/ijst/2016/v9i40/97813, October 2016 ISSN (Print) : 0974-6846 ISSN (Online) : 0974-5645