100% Low-Floor Vehicle Traction Drive System Analysis And Control Strategy Research

100% Low Floor Vehicle (100% LFV) have a lot of merits which make the adoption of 100% LFVs an ideal selection in the field of Urban Railway Transportation. All these starting from the origin of 100% LFV, this paper goes into the analysis of its peculiar traction mode, together with that of the steering problem arising from such mode. Combined with motor control, its traction system and traction control strategy are thoroughly studied, offering a supplement to the shortage of such research in the domestic academic field concerned, and a design approach at the same time.In this paper, the conventional rigid wheelsets and independent wheelsets are analyzed and compared, from which is derived the conclution that Longitudinal Creep Force (LCF) is key in the direction of wheelset. Since there is no such force with independent wheelset, the wheelset is lack in direction ability. This paper proposes the active guiding approach based on torque and velocity, respectively, from the aspects of electrical control approach and with Field Oriented Control Scheme (FOC). The active guiding based on torque, which asserts different torque to the left and right wheels; motivate the wheels to generate the orientation torque needed. The active guiding based on velocity controls the left and right wheels velocity to manipulate the vehicle along the center line of tracks. In this paper, a control system for 100% LFV is introduced, combining the guiding control based on torque and velocity, as well as the traction control scheme of vehicles. With this control system, the traction and guiding control of vehicles can easily be realized with existing converters on board, and related simulated results are also presented in one part of this paper.TheΓ^-1 equivalent circuit is suitable for the analysis of field oritated scheme, thus all the control scheme analysis in this paper is based onΓ^-1 equivalent circuit. In this paper, the merits and shortcomings of current and voltage models are analyzed and compared, and there is also an expiation to the reason for the imbalance of these FOC schemes together with the corresponding influencing factors. Finally, a closed-loop stator flux observer is put forward and FOC with it is looked into in this paper.Dynamic parameters on both sides of longitudinal traction system in independent wheelsets are inconsistency; the proposed distribution current control can effectively reduce the impact of parameters changes. The speed compensator can guarantee its stability and steady-state performance, to achieve harmonization of the independent wheelsets control.Based on theΓ^-1 equivalent circuit, a sensorless control scheme for FOC is proposed with Extended Kalman Filter (EKF), which simplifies state matrix, relieves the computational burden of EKF, and improves the control accuracy by treating the variation of parameters as measuring and state noises. With the model of converter, the real-time stator voltage of traction motor is calculated and the influences on such voltage from dead time and voltage dropdown on switches are analyzed. A correction algorithm for stator voltage is put forward according to such influencing factors, which will improve the accuracy of EKF flux observer, and such theory has been proved to be true in a wide speed range of traction motor. Based onΓ^-1 equivalent circuit, this paper puts forward a speed-sensor-less scheme with EKF, which simplify the state matrix, relieves the computing burden on EKF, treats the parameter drift as measurement and state noise, improves control accuracy and acts as a back-up redundancy in LFV.The traction and braking curves of 100% LFV are designed in this paper, meeting operational requirements. What's more, a set of traction computing software based on definite railway conditions has been developed. This software is available with the simulation of traction-coasting-braking operation under a maximum load along real railway, with the calculation of current and power of traction motor and converters, which will act as a reference of the operational design of a real system. At last, a double-motor mutual traction experiment platform is also designed and built, of which the topology of main power circuit and the structure of control system are thoroughly explained in this paper. All related experimental results are also presented therein, proving the approaches put forward in this paper.