Mode Identification and Collaborative Switch for the Front-Centralized and Rear-Distributed Electric Drive Vehicle Based on BP Neural Network

Distributed-drive electric vehicles (DDEVs) significantly enhance off-road maneuverability but suffer from compromised high-speed stability and robustness. This research introduces a front-centralized and rear-distributed (FCRD) architecture that synergistically leverages the advantages of each configuration. The electric-drive-wheel (EDW) on the rear suspension can provide three working modes: (a) Drive-connected mode, (b) Drive-disconnected mode, (c) Brake mode. It is the key actuator for vehicle mode-switching, which supports the vehicle with three driving modes: (a) DDEV, (b) front-wheel drive (FWD), (c) all-wheel drive (AWD). A hierarchical control architecture employs the upper-layer controller with Back Propagation Neural Network (BPNN) for mode identification and decision-making. The lower-layer controller enables the intelligent torque distribution and collaborative control of the motors. The control strategy is pre-trained in the VCU (vehicle control unit) with off-line data annotations to achieve the maximal instantaneous system efficiency. At the same time, a cost function is designed to suppress unreasonable frequent mode switching that may deteriorate handling characteristics and ride comfort. The off-line data training results indicate that the overall accuracy of mode identification reaches 91.7%, of which the DDEV mode accuracy 98% and AWD mode accuracy 85%. Finally, the test vehicle with the calibrated EDW prototype is fully constructed and drives in Shanghai suburbs for a road test with parameters recorded throughout the whole cycle. The test vehicle has a balanced performance in power output, driving efficiency, and control robustness. The high-way cruising conditions activate the efficiency-oriented AWD mode of 82% overall propulsion system efficiency, which overcomes the problem of high-speed attenuation in electric vehicles and effectively improves the range at premise of safety and stability.