Effect of the unbalanced vertical force of a switched reluctance motor on the stability and the comfort of an in-wheel motor electric vehicle

Abstract

Switched reluctance motors are well suited to in-wheel-motor-driven electric vehicles because of their numerous advantages, such as a high torque density, a high operating efficiency and excellent power-speed characteristics. However, these advantages are overshadowed by their inherent high torque ripple and vibrations. The unbalanced radial force of the switched reluctance motor is one of the main reasons for vibrations of the switched reluctance motor but has attracted less attention for in-wheel motor applications according to previous research. In this paper, the vertical component of the residual unbalanced radial force of the switched reluctance motor, i.e. the vertical force of the switched reluctance motor, is taken into account in the stability and comfort analysis for in-wheel-motor-driven electric vehicles. The results in this paper indicate that the vertical force of the switched reluctance motor has a great effect on the lateral and anti-rollover stabilities of the vehicle. The direct cause of this phenomenon is that the vertical force of the switched reluctance motor is directly applied on the wheels, which will result in a significant variation in the tyre load, and the tyre can easily jump off the ground. Furthermore, the frequency of the vertical force of the switched reluctance motor covers a wide bandwidth which involves the resonance frequencies of the vehicle body's vibrations and the wheel bounce. As a result, the comfort of the vehicle is greatly harmed. Therefore, the effect of the vertical force of the switched reluctance motor on the the comfort of the vehicle is also considerable in some resonance situations. The conclusion is that the vertical force of the switched reluctance motor not only causes the stability of the vehicle to deteriorate but also has a considerable effect on the the comfort of the vehicle, and an appropriate control method for the switched reluctance motor is desired.

Suppression of Switched Reluctance Motor Vibration of In-Wheel Motor Electric Vehicle

“…Because of the geometrically balanced motor structure, the SRM radial force is always considered zero. But the vehicle load and road excitation [17] will yield SRM airgap eccentricity, due to which, the radial force is always not zero. In this study, The primary objective is to reduce the vertical vibration of SRM and the negative influence on vehicle dynamic performance, the well-known 6/4 outside-rotor SRM, like [18,19], is shown in Figure 1.…”

“…In the previous work, we analyzed the influence of the SRM unbalanced radial force on comfort and stability of IWM-EV. The conclusion [16,17] shows SRM vertical force is highly coupled with road excitation and SRM airgap eccentricity, and this coupling yields SRM vertical vibration that does harm to comfort and stability. This study used electromagnetic active suspension and linear quadratic Gaussian (LQG) controller to reduce the SRM vertical vibration and the negative influence on vehicle dynamic performance.…”

Thrust Ripple Force Minimization and Efficiency Analysis of Electromagnetic Actuator on Active Suspension

“…In-wheel motor has become a new development direction on an electric car because of reducing chassis space, short transmission chain, and high efficiency. However, the riding comfort and stability of the vehicle are deteriorated due to the increase of unsprung mass [1][2][3]. e traditional suspension is composed of spiral spring and hydraulic shock absorber.…”

Ride Comfort Optimization of In-Wheel-Motor Electric Vehicles with In-Wheel Vibration Absorbers

“…Nevertheless, challenges, such as vehicle ride comfort, still remain with IWMEVs due to the heavy electric wheels. As a matter of fact, the unsprung mass with the IWMs usually results in harsh vertical negative effects, such as reduction of vehicle ride comfort [4][5][6], deterioration of road friendliness [7], invalidation of suspension control methods [8], and reduction of motor reliability under the large wallop [9][10][11], which have greatly restricted the practical development of IWMEVs.…”