Shumei Cui

The Study of the Operation Modes and Control Strategies of an Advanced Electromechanical Converter for Automobiles

To enhance the performance of hybrid electric vehicle and continuously variable transmission, and to achieve more varied operation modes, a novel breed of integrated electromechanical converter is presented, such as electrical variable transmission (EVT) and four-quadrant transducer. Synthesizing two electric machines, they are essentially electromagnetic theory-based converters with the function of speed, torque, and energy regulation. The feature of flexible and variable control makes them very suitable for use in automobiles, especially in hybrid electric vehicles, as a continuously variable transmission and integrated starter and generator. Furthermore, the operation of the internal combustion engine is optimized, and the reduction of fuel consumption and the improvement of vehicle performance are also achieved. Corresponding to different road loads and driver demands, several operating states and control strategies are possible. Based on a simplified structure, the mathematical model of the EVT has been built, and its power flow and control strategies under different operation modes, are also analyzed

Study on Improving the Performance of Permanent Magnet Wheel Motor for the Electric Vehicle Application

The wheel motor directly drives the vehicle, so its structural and electromagnetic design has some difficulties, and it will affect the performance improvement of the motor. Based on the exterior-rotor radial-flux permanent magnet (PM) wheel motor, we have done relative study on improving the motor performance from four aspects: magnetization direction and pole number; no-load air-gap flux density; no-load electromagnetic force (EMF); and flux insulation. Theoretical analysis, design data, and simulation results are given in this paper, and we have developed a first-round prototype LQI based on them

Development of PMSM Drives for Hybrid Electric Car Applications

Permanent synchronous electric machine (PMSM) drives for the FAW hybrid electric car is investigated in this paper. The power system configuration of the FAW is introduced. The influences of the stator winding turn and the permanent magnet width on the torque-speed characteristic are analyzed. The torque-speed characteristic that the specification required is obtained by proper choice of these two parameters. The torque ripple and the harmonic contents of the electromotive force (EMF) are decreased by rotor shape optimizing to improve the traction performance and the supply quality. The rotor shape is optimized by the offset arc method. The analysis is verified by the sample PMSM experimentation

Design and Simulation of a Self-Excited All-Air-Core and Fabrication of a Separate-Excited All-Iron-Core Passive Compulsator

This paper presents a detailed description of design and simulation of a self-excited all-air-core and fabrication of a separate-excited AU-iron-core compensated pulsed alternators (compulsator), also including the similarity and difference in configuration and principle of two prototypes. Presented are fabrication techniques, assembly processes and design methods developed specifically for pulsed power generators, including the carbon fiber rein-forced epoxy resin composite material usage of stator and rotor core in all-air-core compulsator, and the armature and field winding fabrication techniques and conglutination processes in All-iron-core compulsator. The armature winding is wound concentric winding by flat copper bars, the end-turn superposition problem solved by heating the flat copper bar to soften them for taking shape. Designs of a lightweight self-excited all-air-core rotating-field passive compulsator and a separate-excited AU-iron-core compulsator for comparison have been completed. They all have rotating-field, two-phase, four-pole, and slotless armature winding and passive compensation .The heart of the self-excited all-air-core passive compulsator is carbon fiber rein-forced epoxy resin composite rotor which rotates at 10000 rpm or more, and that epoxy composite resin stator reduces the saturation of the compulsator, which consequently reduces transient inductance of armature winding and increasing the magnitude of pulsed current. The usage of composite material also reduces the mass of the all-air-core compulsator and increases the velocity of the rotor and inertial energy storage, therefore increasing the energy density and power density. Another feature of the all-air-core PCPA is the use of two armature windings on the stator, which allows optimization of each armature winding to its specific duty cycle. Control of self-excited process is presented as well as the synchronous control of solid-state switch in excitation circuit and discharge main circuit by the special controller. The paper presents the simulation of magnetic field at no-load and discharge instance respectively. The paper analyzes the impact of the thickness of compensation shield to the performance of compulsator. Finally, the experiment schematic of all-air-core compulsator system is presented.

The torque pulsation analysis of a starter generator with concentrated windings based hybrid electric vehicles

In hybrid electric vehicles (HEV), the emissions of HEV are affected by the start torque performances of the starter generators (SG) greatly. Due to the limitation of vehicle space, usually they are made for flat shape. To improve the output torque and efficiency of the SG, the stator windings are designed into concentrated windings, however the torque ripple will be increased greatly. In this paper, the torque ripple of the SG with concentrated windings is analyzed. A two dimensional finite element analysis (FEA) method along with an average technique is used to evaluate the torque ripple. To reduce the torque ripple, three SG with different structures are designed. Considering the practice the integrated evaluation is provided.

Simulation research of CPA powered railgun system

The railgun, as a novel kinetic energy weapon, is being taken seriously by each country military. The pulse power source and railgun barrel, directly related to the performance of the total system, are important parts of the railgun system. The compensation pulse alternator, with its high energy storage density and power density, becomes one of the most potential pulse powers. The simulation of the pulse generator powered railgun system is researched in this paper. In order to accurately simulate the characteristic of the railgun system, the time-varying characteristic of the parameters and the kinetic resistance are taken into account in the process of building the raigun model. The railgun model is completed through the Matlab/simulink. The generator model is set up in FLUX. The coupling module between the two softwares is utilized to realize the co-simulation of the railgun system. The simulation results show that the optimum length (the displacement of the projectile exiting the muzzle while the current exactly reduces to zero) of the barrel has the relation with trigger moment of alternator. The velocity of the projectile will decrease when the trigger moment is delayed or the distance between the breech and the armature becomes further.

Sensitivity analysis and regulation strategy of current waveform for two-axis compensated compulsators

Compulsators have been considered as appropriate pulsed power supplies for electromagnetic railguns. In order to ensure a high projectile peak to mean acceleration ratio, it is desirable to provide a flat-topped pulse for the railgun. This paper analyzes a two-axis compensated compulsator, which is a refined selective passive compulsator having an orthogonal displacement between compensating winding and field winding. During the discharge process, the quadrature-axis compensation is provided by the compensating winding, when direct-axis compensation provided by the field winding. Compare to traditional selective passive configuration, this arrangement is able to provide another degree of freedom to compensate the armature reaction, thus output a current waveform with more flexibility. In this paper, the self-excitation and discharge process of a two-axis compensated air-core compulsator is simulated based on a finite-element model. Analysis of current waveform sensitivity to compulsator design parameters is also carried out, as well as the regulation strategy to generate a flat-topped pulse. The research process mentioned in this paper could help to optimize design of compulsators in future applications.