Abstract:In this paper, a continuous steering stability controller based on an energy-saving torque distribution algorithm is proposed for a four in-wheel-motor independent-drive electric vehicle (4MIDEV) to improve the energy consumption efficiency while maintaining the stability in steering maneuvers. The controller is designed as a hierarchical structure, including the reference model level, the upper-level controller, and the lower-level controller. The upper-level controller adopts the direct yaw moment control (DYC), which is designed to work continuously during the steering maneuver to better ensure steering stability in extreme situations, rather than working only after the vehicle is judged to be unstable. An adaptive two-hierarchy energy-saving torque distribution algorithm is developed in the lower-level controller with the friction ellipse constraint as a basis for judging whether the algorithm needs to be switched, so as to achieve a more stable and energy-efficient steering operation. The proposed stability controller was validated in a co-simulation of CarSim and Matlab/Simulink. The simulation results under different steering maneuvers indicate that the proposed controller, compared with the conventional servo controller and the ordinary continuous controller, can reduce energy consumption up to 23.68% and improve the vehicle steering stability.

In order to improve the steering stability of a four in-wheel motor independent-drive electric vehicles (4MIDEVs) on a road with varying adhesion coefficient, such as on a joint road and a µ-split road, this paper presents a hierarchical electronic steering control (ESC) strategy. The upper level controller of the proposed ESC strategy achieves the adaptive control of the yaw rate and sideslip angle in the direct yaw-moment control based on the influence of road adhesion. The lower level controller is designed as a twohierarchy structure, which can adaptively change the torque allocation algorithm and achieve different weight controls of each wheel torque according to road adhesion coefficient. The results of real-time simulation conducted in the RT-LAB testing platform and a real-car test indicate an improvement in the steering stability of the 4MIDEV on a road with varying adhesion coefficient. Particularly the ''double lane change'' testing carried out on a joint road and a µ-split road shows a yaw rate error reduction of up to 55.1%, compared with the ordinary control strategy, with output torque and its fluctuation of each in-wheel motor significantly reduced. INDEX TERMS Electric vehicles, independent-drive, stability, adaptive control, adhesion coefficient.

In order to solve the problem that the conducted interference voltage of a high voltage/low voltage (HV/LV) DC-DC converter for vehicles exceeds the standard CISPR25-2016, two different design methods of EMI filter for HV power supply were proposed. The first method is to design a wide-band EMI filter at the high-voltage input port of the DC-DC converter. It can achieve the insertion loss of 60dB within 150kHz-108MHz. Another proposed method is to design a PCB-level EMI filter based on the resonance peaks suppression. During the PCB-level EMI filter design process, a high frequency equivalent circuit model of HV/LV DC-DC converter of EV considering the parasitic parameters was established, and by establishing the transfer functions at key frequencies of 200 kHz and 2 MHz, the dominated parameters responsible for the over-standard points were determined. From simulation and experiment results, the filters designed by above two methods can effectively reduce the conducted disturbance and comply with the limits requirements in 150kHz-108MHz. What's more, the PCB-level filter designed by the second method is smaller in size, only 1/5 of the filter size designed by the first method, lower in cost,and easy to be engineering.INDEX TERMS Electric vehicle (EV), DC-DC converter, conducted electromagnetic interference (EMI), EMI filter, EMI suppression.

A steering stability control method for four-motor distributed drive high-speed tracked vehicle is proposed to improve handling stability and safety. The dynamic analysis and calculation of center steering, small radius steering and large radius steering for the four-motor distributed drive tracked vehicle are carried out respectively. In order to meet the power requirements of the outer drive motor in high-speed steering, a steering coupling system is constructed, which uses a steering motor to couple with the traction motor at the rear left or rear right side of the tracks respectively. The steering stability control strategy with the steering coupling takes the yaw angular velocity and longitudinal speed of the vehicle as the control objectives, and a direct yaw torque control strategy is proposed to optimize and distribute the torque of four traction motors in real time according to different steering conditions, and considers the synchronization of two traction motors on one side of the track, so as to improve the steering stability, safety, comfort and steering trajectory performance of the four-motor drive tracked vehicle. The simulation results of 0B, 0.2B, 2B and 8B steering radius show that the proposed control strategy with coupling system can ensure the steering stability for the four-motor distributed drive high-speed tracked vehicle. INDEX TERMS Four-motor drive, tracked vehicle, steering stability, power coupling.

In order to enhance the steering stability of a four hub-motor independent-drive electric vehicle (4MIDEV) on a road with varying adhesion coefficient, for example on a joint road, this paper proposes a hierarchical steering stability control strategy adapted to the road adhesion. The upper control level of the proposed strategy realizes the integrated control of the sideslip angle and yaw rate in the direct yaw moment control (DYC), where the influences of the road adhesion and sideslip angle are both studied by the fuzzy control. The lower control level employs a weight-based optimal torque distribution algorithm in which weight factors for each motor torque are designed to accommodate different adhesion of each wheel. The proposed stability control strategy was validated in a co-simulation of the Carsim and Matlab/Simulink platforms. The results of double-lane-change maneuver simulations under different conditions indicate that the proposed strategy can effectively achieve robustness to changes in the adhesion coefficient and improve the steering stability of the 4MIDEV.