In permanent magnet synchronous motor (PMSM) servo systems, the saliency ratio is an important factor in sensorless control and flux-weakening control. Compared with the interior PMSM (IPMSM) with distributed windings, the IPMSM with concentrated windings gains more popularity in servo system applications. However, the saliency ratio of current fractional slot concentratedw i n d i n g s(F S C W s)I P M S Mi sl o wa n dh a r dt oi n c r e a s e ,w i t h o u tm u c hl i t e r a t u r e investigating how to improve the ratio. In this paper, the components of d-a n dq-axes inductances of FSCW IPMSM are determined, a novel concept named mechanical phase region is introduced and the key parameters influencing the saliency ratio of FSCW PMSMs have been investigated through thorough theoretical analysis and simulation. The design principles on increasing the saliency ratio of FSCW IPMSMs are proposed and the maximum saliency ratio of a 10 poles 12 slots motor is obtained. On the basis of the theory, a novel rotor structure with higher saliency ratio is designed. A new experimental method of measuring d-a n dq-axes inductances closest h i sp a p e rw i t ht h r e e experimental prototypes built to verify the theory and simulation results.
With the increasing traffic volumes on freeway systems nationwide, maintenance and construction work zones become more important to consider. These work zones are often in the form of the closure of one or more lanes, which will result in capacity bottleneck and impact the stabilization and safety of freeway. To reduce the influence of lane closure, this paper designs the control flow of Intelligent Lane Merge Control System (ILMCS) with ITS techniques, and constructs Traffic Information Collection System, Traffic Information Process and Decision System and Traffic Information Release System of ILMCS. The system identifies traffic states by analyzing real-time data collected by traffic detectors and then adopts adaptive lane merge control strategies by analyzing the extent of traffic congestion. At last, the paper evaluates ILMCS performances by simulation. The results show the performances of ILMCS exceed conventional merge controls, dynamic early merge control and dynamic late merge control, especially in improving freeway work zones safety and capacity.I.
This paper investigates the effect of eccentric rotor on the eddy losses in high speed external rotor PMSM, which is used in Flywheel Energy Storage System (FESS). Analytical expressions for the no-load magnetic field distribution with static and dynamic rotor eccentricities are presented. The relationship between additional eddy loss and eccentricity ratio is given. Then the finite element simulations are used to analyze the rotor loss and the eddy current distribution respectively due to different types of eccentricity (static and dynamic eccentricity) and eccentric angles. It is showed that static eccentricity makes rotor eddy loss multiply increase and dynamic eccentricity at a specific angle will cause the eddy current loss concentrated in certain magnet.
Short-term traffic flow forecast plays an important role in transit scheduling. A high-order generalized neural network model is constructed to actualize dynamic forecast on-line and a hybrid genetic algorithm and identical dimension recurrence idea are performed to optimize the structure and shape of neural network dynamically so as to enhance its forecast accuracy. With data collected from Dazhi Str., Harbin as the system input, the experimental result indicates that the average relative error of forecast is 5.53% and the maximum is less than 21%, which proves that the proposed neural network model can satisfy the precision request, accelerate the convergence speed, improve the global generalization ability and possess the practicality in short-term traffic flow forecast.
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