Cui Shumei

Study on efficiency calculation model of induction motors for electric vehicles

The efficiency of induction motors for electric vehicles must be researched deeply over the entire operating speed region. Up to now, the calculation models of the efficiency of the induction motor for electric vehicles are less accurate over some operating regions, such as owing to omitting the variations of the motor parameters with frequency. The paper puts forward a calculation model of the induction motor efficiency in the entire region of operation, including the constant-power region and the constant-torque region. And in this paper, the new methods of the iron loss calculating and stray loss calculating are deduced. With the model, the efficiency influenced by motor parameters can be considered at the stage of the motor design. So the optimal design could be done for the high efficiency of motors. The validity of the model has been verified by the experiment results of the 30 kW induction motor.

Design and Experimental Research on Induction Machine based Electrical Variable Transmission

The Electrical Variable Transmission (EVT) is a brand new type of electromechanical converter with double-rotor structure, which can replace the gearbox, clutch, starter and generator in a vehicle. This paper deals with the design principles of EVT. Based on the proposed design principles, an induction EVT prototype was designed, built and tested; this EVT is aimed for light-duty car application. In order to achieve higher power density, the outer rotors yoke is decreased. Both simulation and experiment have been carried out to analyze the Magnetic Flux Coupling (MFC) for this EVT.

Advantages of electrostatic micromotor and its application to medical instruments

In this paper, electrostatic micromotor and conventional electromagnetic micromotor are compared. According to their different operation principles, the paper firstly analyzes the scaling effect of driving forces. Characteristic dimension L represents the linear scale of the micromotors. Electromagnetic driving force is proportional to high-order power of characteristic dimension L whereas electrostatic driving force is not. So, in micro domain, the effect of electrostatic force is larger than that of electromagnetic force, which makes electrostatic micromotor more competitive against electromagnetic alternative in MEMS. In assessing the performance of the micromotor, the power per unit volume and efficiency are the two most important criteria. Hence, the paper further compares the two kinds of micromotors from these two aspects. The results indicate that electrostatic micromotor has higher power per unit volume and efficiency, moreover, its structure is simple, it can be made sufficiently small. For those advantages of electrostatic micromotor, the paper finally discusses its application to medical instruments.

The construction and simulation of V2G system in micro-grid

Vehicle-to-Grid (V2G) technology has caught peoples attention. Applications of V2G in general Power Grid face some challenges. It is complicated to control, in need of large amounts of EVs and hard to realize in the short term. In this paper V2G is applied to micro-grid and V2G system is constructed based on a parking lot. The structure is proposed in which bidirectional AC/DC and bidirectional DC/DC converters share one common DC bus, and also the coordination control strategy is given. Meanwhile this paper presents a general micro-source model as well as a V2G model. Simulation of voltage regulation and renewable energy support is conducted and results prove the availability of proposed structure and control strategy. The work is meaningful to the control and operation for micro-grid and V2G.

Hybrid Switched Reluctance Motor Applied in Electric Vehicles

Electric motor is key part in electric vehicles including hybrid electric vehicle, fuel cell electric vehicle and battery electric vehicle. Wide torque-speed range and high reliability are needed of the motor applied in electric vehicles. Novel hybrid switched reluctance motor is developed. It combines features of robust as switched reluctance motor and that of high efficiency of permanent magnet motor. Flux strengthening and weakening control give large maximum torque and high speed to the motor drives. They are implemented by only simply controlling the magnitude and direction of the current in an additional coil in the motor. Rotor position is detected by the signal from stationary coils in the motor and rotor speed is calculated according to this signal. To test characteristics of the motor drives, an experimental bench is developed. It is easy to test four quadrants torque-speed and dynamic characteristics of the motor drives. The whole testing system is energy saving.

The Research of Regenerative Braking Control Strategy for Advanced Braking Force Distribution

Regenerative braking system is the characteristic system of electric and hybrid electric vehicle. The system can restore the kinetic energy and potential energy, used during start and accelerating, into battery through electrical machine. A control strategy witch is based on ideal braking force distribution is proposed. Front wheel and rear wheel can make full use of ground adhesion condition with the strategy when the vehicle brakes. More regenerative braking energy is reclaimed on the premise of ensuring braking efficiency. A simulation model is built in ADVISOR, and then put in vehicle model to simulate. The result proves that more effective braking energy is reclaimed and vehicle fuel economy is improved.

Rotor Slots Design of Induction Machine for Hybrid Electric Vehicle Drives

Rotor slot design of the induction motor for hybrid electric vehicle drives is investigated in the paper. Rotor slot types of the induction machine for variable frequency drives are deferent from that of the induction machine for industry applications. Improper rotor slot design will lead to bad torque performance and unwished noise of the induction machine. Three common rotor slot types of the induction machine for variable frequency drives are analyzed. The advantages and disadvantages of them are indicated. Comparing torque and efficiency of deferent rotor slot shapes, the optimal value is obtained by finite element analysis. The influence of the slot combination on the noise of the induction machine is analyzed. Magnitudes and frequencies of primary electromagnetic force modes of a sample induction machine is calculated by the finite element analysis. Vibration magnitudes of the stator and the sound power levels of the electromagnetic noise are estimated. Experiment of the sample induction machine is done to prove the analysis

Optimization of Switching Rule and Operating Modes of Hybrid Electric Vehicles

The paper introduces the configuration of hybrid electric vehicle (HEV) system, and analyses operating modes and switching rule base on the hybrid system theory. The HEV is a typical hybrid systems; a research on hybrid characteristic of HEV is presented. The switching system of HEV is a kind of hybrid systems. It is including of both continuous state variables and discrete events variables; the advanced control method is used in the design of the hybrid control unit (HCU), HCU designs the switching rules strategy, which aims to solve the problem of the power distribution between the internal combustion engine (ICE) and electric motor. It can effectively resolve process control problems of the complex HEV system, optimize the operating modes switching, and the good performance of control can be obtained

A simple diagnosis of winding short-circuited fault of PMSM for electric vehicle

The negative-sequence current analysis is a classical method of single phase winding short in the PMSM. In this paper, a simple method is presented for on-line winding short circuit fault detection. It consists of a new calculation of negative sequence current based on negative-rotating synchronous reference frame. The amplitude of negative-sequence current is used as the indicator reflecting the severity of inter-short fault. The fault-detecting method is implemented very easily for electric driving system based on vector space control. A simulation is presented to verify the application proposed method.

Electromagnetic Shields of the Air-Core Compulsator

Air-core compulsator is a specially designed generator capable of delivering high current pulses to a low-impedance load, such as the electromagnetic railgun. Due to the absence of ferromagnetic material, the field strength in air-core compulsator can reach 4-6 T. Therefore, electromagnetic shields are required to protect the surrounding operators and instruments from exposure to high magnetic fields. This paper investigates the design methodology of the shield as well as its influence on the performance of the machine. A dynamic model is built to analyze the shielding effect and its performance tradeoffs of a reference compulsator. The result indicates that the effect of the eddy-current shield is much better than the magnetic shield using ferromagnetic material, due to the high frequency and the magnetic saturations. The magnetic field can be completely screened inside the conducting shield, at the expense of some electrical, mechanical, and thermal performance. Since the eddy-current density is sensitive to the location of the shield, the influences of the conducting shield are parametrically analyzed. Using the electromagnetic and thermal coupling field link, the temperature rise of the shield is also calculated. Analysis results can provide the theoretical guides for the shielding of the air-core compulsator investigation in the future.