Flatbed Multi-motor Drive With Anti-skid Control

As energy and environmental issues have become increasingly serious, researchers around the world have been involved in the research of the EV since the 80s of the 20th century. Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Fuel Cell Vehicle (FCV) have been developed successfully, all of which are light or medium duty vehicle. However, electric or hybrid drive system is rarely adopted on heavy duty vehicle except electric locomotive. In this paper a compact light duty series hybrid electric experimental vehicle has been studied driven by multi-motor driving system, which provides a theoretical reference for the heavy duty flat transporter.Several driving systems and control methods of multi-axles transporter are summarized based on previous research achievements. A simplified kinetics model has been established including tire model, rotating dynamic models of wheels, transmission system, and the relationship between the wheel and adhesion coefficient. A linear dynamic equations of experimental vehicle has also been built.After comparing various motors of their merits and shortcomings for traction system, permanent magnet synchronous motor (PMSM) is selected for experimental vehicle driving system and the math model of PMSM is set up. Rotor field oriented control (RFOC) of vector control system is designed for the control of PMSM. The algorithms of space vector pulse width modulation (SVPWM) and direct torque control (DTC) have been emphatically studied.Comparing to hysteresis current control strategy, SVPWM can achieve the accuracy and reliability speed and torque response.The characteristic of speed and torque control mode has been analyzed. According to the actual working condition of the experimental vehicle, this paper presents a dual mode switching control based on wheels slip ratio. When wheels slip ratio is small speed control mode is employed. In order to reduce synchronization errors, adjacent cross-coupling strategy is designed. In addition, a variable structure control (VSC) with an integral sliding surface and exponential reaching law is designed for speed controller. The simulation results illustrate the effectiveness of the proposed control on the premise of wheels small slip ratio.However, torque control required when wheels slip ratio is big. Electric motor torque can be controlled much more quickly and precisely that of internal combustion. So we propose the acceleration slip regulation (ASR) called the optimal slip ratio control. The effectiveness is demonstrated by simulation results, and the vehicle stability and safety are greatly improved by motor torque applied to the wheels big slip ratio.Research results show that sliding mode control with adjacent cross-coupling strategy including multi-motor synchronous vector control can achieve the accuracy and reliability of the synchronous control system.