Pei Yulong

The Performance Research of Starter-Generator Based on Reluctance Torque Used in HEV

The objective of this paper is to describe the role that reluctance plays in interior permanent magnet (IPM) starter-generator (SG) analytically. 4-pole and 6-pole models of SG including the radial and tangential flux are analyzed. For increasing the value of q -axis reactance, several possible factors are considered. The stationary torque versus control angle was predicted by finite element analysis (FEA). The permanent magnet and the reluctance components of the torque were analyzed and computed. The results show that the rotor shape, magnet length, magnet thickness and the amount of poles etc., will observably affect the component of the reluctance. One working prototype of the SG-1 was built and fully tested. The motoring torque within 1700 rpm and the generating power within 6000 rpm were measured. The motoring power can supply 8 kW at 1700 rpm and the torque can keep constantly with 45 Nm; Generating results have proven that the ISG is capable of meeting the specification for output power 4 kW up to 6000 rpm and the maximal speed can reach to 7927 rpm. In addition, the efficiency contour maps of motoring and generating are obtained by experiment. The results show that the prototype has wide high efficiency region. The FEA prediction and experiment results were proved well. The improved prototype SG-2 was simulated by FEA. SG-2 is a radial-flux structure machine, and its utilization of permanent magnet and the saliency ratio are both higher than SG-1. The results show that no matter constant torque ability or the constant power range, compared with SG-1, SG-2 both has an improvement to a large extent.

Study on Intelligent Lane Merge Control System for Freeway Work Zones

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.

Axial excited hybrid reluctant motor applied in electric vehicles and research of its axial coil signal

Characteristics of traction motors for electric vehicles (EV) should be high power density and high efficiency over the whole working area. The axial excited hybrid reluctant motor is fit for the EV application. In the motor, there are three excitation sources, which are permanent magnetic, armature, and axial coils. Controlling these excitation sources will make the motor run in different modes, which satisfy many kinds of conditions of the vehicle. With special structure and electromagnetic design, the electromagnetic torque includes reluctant torque, and the torque per unit volume is improved. Controlling the axial coil current will adjust the main flux. Then the flux weaken control is convenient achieved. When it is used as generator, main flux can be adjusted. The axial coil can also be used as position sensor. The electromotive force signal denoting the rotor position is added on the dc voltage applied on the axial coils. The paper introduces the structure and principle of the axial excited hybrid reluctant motor and resolves the electromagnetic torque. The axial magnetic field is analyzed. And the relation of the emf of the axial coils with the rotor position is produced. The simulation and experiment are made. The result shows that characteristics of this novel type motor satisfied the demands of the traction motor for EV.

Design of the double-stator permanent magnet synchronous starter and generator used in electric vehicles

Integrated starter/generator designs the flywheel, the flywheel cover and clutch as a whole. To meet the size requirements of space, a double-stator permanent magnet synchronous starter and generator was designed to realize both performance of starting and generating. This paper presents a new permanent magnet double-stator integrated-starter-generator (ISG) for hybrid electric vehicles (HEVs). The double-stator permanent magnet synchronous starter-generator was designed to have different number slots in inner stator and in the outer stator and poles at double attached magnet rotor is also different. Two machines consist of the outer stator, the inner stator and double attached magnet rotor two machines with different combinations of poles and slots to can be designed separately to achieve optimum performance and to meet the demand of different operation modes. Both the performance of starting and generating of double-stator permanent magnet synchronous starter/generator is simulated by finite element analysis, the advantages of the double-stator structure was presented.

Analysis of 3D static temperature field of water cooling induction motor in mini electric vehicle

In this paper, the finite element model of the three-dimensional steady-state temperature field for a miniature water-cooled induction motor was established. The effective thermal conductivity was introduced to simplify the complex heat transfer process in the air gap. The heat losses of various parts of the motor were calculated, as well as the chassis water jacket heat exchange coefficient based on the similarity criterion of fluid. By three-dimensional finite element simulation, the three-dimensional steady-state temperature field distribution under rated load and the temperature field distribution under various flow rates were obtained. The simulation results showed that the highest temperature rising is located in the rotor, the temperature difference between the rotor core and the rotor bar is small, the highest temperature appears at the axial center of the motors rotor bar, the temperature rising of the stator winding is higher than that of the stator yoke, the lowest temperature rising occurs at the motor case, the change of flow rate has more effects on stator yoke and motor case, little effect on stator winding and the rotor. Under turbulent flow, the decrease of the motor temperature rising is very small with the increasing of the flow velocity. Experiments were conducted on a 34V, 4kW mini-electric-vehicle-used induction motor to measure the temperature of the stator windings, the winding ends and the stator yoke department under rated load and various flow rates. The numerical simulation results are consistent with the experimental results.

A Calculating Method of Intersection Delay under Signal Control

The paper presents a calculating method of intersection delay under signal control. Adopted signalized intersection theory and on the foundation of existing delay research, the paper has further divided three traffic conditions of under-saturated, critical-saturated and over-saturated into six traffic situations and then the paper has inferred the corresponding approach delay formulas for each of them. The paper has also analyzed selecting term for choosing approach delay formulas and has established the approach delay model of signalized intersection. After that, the paper has inferred intersection delay formulas of signalized intersection with three phase controlled under different traffic conditions, then, the paper has proposed a calculating method for intersection delay under signal control, that is: it should choose the corresponding approach delay formula to calculate approach delay of every intersection approach based on different traffic conditions, different signal phase sequence and the number of queued vehicles at the beginning of signal cycle, and then sum up all approach delay to get intersection delay. Finally, the paper uses two cases to illustrate how to use the method to calculate intersection delay.

The application of cusp Catastrophe theory in traffic flow prediction

Traffic flow prediction plays an important role in traffic management and control. The focus of this paper is to discuss the application of cusp catastrophe theory in traffic flow prediction in China. Five properties of a catastrophe system are outlined briefly and the data collected from freeways of Zhujiang Delta, Guangdong province, China are examined to ascertain whether they exhibit qualitative properties and attributes of the catastrophe model. This paper also tries to describe the relationships between traffic parameters by using cusp catastrophe theory and to acquire highway capacity and corresponding speed prediction value through suitable transformation of catastrophe model. The forecasting value of speed and capacity for freeway sections are given based on the catastrophe model. Furthermore, speed-flow curve on freeway is drawn out by means of plotting out congested and uncongested traffic flow and the capacity value for the same freeway is also obtained from the speed-flow model curve to test the feasibility of the application of cusp catastrophe theory in traffic flow. Finally, prospects and problems of its application in traffic flow research in China are discussed.

A hypothesis based on traffic pressure and its application on evaluating level of service for basic freeway segments

After the application of ITS (Intelligent Transportation Systems), a security travel at high volume and speed is hoped but a travel at low volume and high speed. Therefore the level of service is regarded as relative high when traffic flow operates safely under high volume and speed (also high density). This is just the target of ITS. The concept of service saturation or relative level of service is proposed to explain the above thinking in this paper. A traffic flow continuity hypothesis based on traffic pressure is brought forward. Analogy relationship between traffic flow and fluid flow is adjusted. Contrasting fluid mechanics and traffic flow, the concept of traffic pressure under steady traffic flow is defined. The concept of relative traffic pressure P~ is interesting. There is always P~/spl les/1 under any traffic condition (it may be negative or positive). Based on continuum equation set up, viscosity momentum differential equation is given. The feasibility of evaluating level of service (LOS) of highway by non-dimensional traffic pressure is analyzed and field data collected by using traffic detectors on Guangzhou-Foshan freeway in south of China are used to verify the hypothesis proposed in this paper. It is concluded that the observed data show that non-dimensional traffic pressure could be used to evaluate LOS.

Influence of inductance on position signal estimation of SynRM for different winding connection

This paper presents the utilization of sensorless position control technology by PWM high-frequency injection for SynRM, one possible structure of SynRM applied to sensorless control and two different winding connections of SynRM as well as experimental test and FEA of phase inductance. The theoretical analysis indicates obvious influence of phase inductance wave on position signal estimation when the two different winding connections adopted. The influence on signal precision is compared after experimental study on two prototypes developed without position-sensor. As proved by experiment, this method makes it possible to assess the position angle of rotor accurately and unfailingly start the rotor in random position.

Study on Traffic Flow at On-ramp Junctions in Urban Freeway with Cellular Automaton Model

Numerical simulation was applied to study on-ramp junctions area traffic flow characteristics using one-dimensional cellular automaton (CA) model, which based on analyzing the traffic flow action characteristics. In course of study, we constructed some reasonable lane-changing rules to analyze the special traffic flow characteristics, affected by parameters of traffic volume and inflow rate, which based on setting up. The results showed that there was a slight disturbance with the inflow to mainline flow at the moment of little probability of the inflow. However, with the inflow probability increasing, the mainline flow would be suffered from a serious disturbance. Especially, traffic jam could be produced when the mainline and on-ramp volumes increasing to a certain level. But for the outflow, the cases are completely different, mainline exit section will be at the phase of saturation when the inflow probability exceeding 0.5. The results can provide some references for managing the on-ramp junction traffic system.