| Electric traction drive system is the coral and difficult part of metro vehicle. The vector control technology for induction motor, anti-skid/anti-slip control technology for vehicle and stability control technology for electric traction drive system are researched in this paper, then amounts of simulations, ground tests and field trails are carried out to verify the theoretical research results.Under low switching frequency of metro traction converter constraint condition, according to the pole map of induction motor based on complex model and the discretization error function based on matrix frobenbius-norm, the problems and application limitations of conventional discrete full-order rotor flux observer are pointed out; a novel discrete full-order rotor flux observer based on re-organization of state space is proposed, which has stable and convergent observed result, minimal discretization error and small computation with limited frequency calculation in full speed range; meanwhile, in order to optimal assigning the poles, the feedback gain matrix are designed, which not only increases the rate of convergence, but also improves motor parameter sensitivity; using observed result to propose an accurate rotor flux orientation correction strategy based on error compensation to flux q axis component, which insures the veracity of rotor flux orientation for induction motor.Internal coupling factors of induction motor are concluded and summarized, then the effects of digital control delay are pointed out based on existing timing of digital controlled closed-loop current; by making use of system coupling function, this paper analyzes the decoupling performance of conventional current controller, an inproved current controller based on pole zero cancellation is proposed by researching the relation between coupling effect and pole distribution of current loop system, at the same time, Tustin is introduced so as to complete the digitalization of the inproved current controller, which not only has good dynamic response, but also realizes the decoupling control of stator current excitation and torque variable.According to adhesive analysis for metro vehicle, this paper finishes the establishment of vehicle dynamics model by converting the model from double axle to single axis; the first order disturbance observer is introduced in order to obtain the current road's adhesion coefficient and its derivative value, an anti-skid/anti-slip control technology for metro vehicle based on PI regulator and torque adjustment function is proposed by means of researching the characteristic of peaks of adhesive characteristic curve and combining with logic control for metro vehicle, which not only prevents skid/slip phenomenon, but also realizes optimized adhesion utilization under the condition of dirty road.Based on analysis of main circuit of electric traction drive system for metro vehicle, comprehensive linear model of system is established; the influence of DC input filter parameters and vector control technology for induction motor on system stability is studied using the analyze method based on loop gain of cascade electrical system; in order to insure the stability of electric traction drive system of metro vehicle in full speed range and any operating condition, an improved stability control strategy based on impedance matching is proposed, which can timely adjust the input impedance model of traction converter-induction motor system. |
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