Research Of The Electromagnetism Key Questions And Temperature Field Of Motor/Generator For Flywheel Energy Storage

With the rapid development of the world economy, human beings are facing to thechallenges of strengthen economic and sustainable development for the social, environmentprotect and energy problem is very outstanding. Energy storage was an important way foreffective utilization of energy, and it was a major direction to solve the energy crisis problem.The flywheel energy storage (FES) has the advantages of long life, high power density, highenergy storage densities, basically has not limited by times of charging and discharging, easyinstallation and maintenance, without pollution etc. So the FES was a new storage techniquewith wide application prospects.This issue is supported by the fundamental research funds for the central universities:study of the high speed motor/generator (M/G)(HEUCF111705) and the optimal efficiencystudy of the M/G for the FES (HEUCF101706). The M/G study is major served for the energystorage technology in the marine field. The purpose was to improve the power quality of amarine power system (MPS) and strengthen the energy recycle, improve the stable of theships electrical power system. Base on the study of600Wh single unit operation FES, deeplyresearch of the electromagnetism key questions and temperature field of M/G for FES system.Through calculating of the index of the energy and rotate speed for the FES system, thengetting the parameters index of the M/G, and to calculate to the basic magnetic circuitparameter calculation and design structure. In this paper, deeply analyzing the running stateof FES system, and put forward the specific operating conditions of the M/G. Grading currentmotor state control and constant power then constant current generator state control has beendesigned for the m/G. this control method not only make the FES system of each index andparameters relationship became clear, and provide theoretical reference for the finite elementanalysis(FEA) calculation of M/G, and provide the theory reference for other electricalmachine design.The different stator and rotor structure and the different PM magnetization form how toinfluence the performance of electrical machine has been study, and analyzes the change rulesof the core magnetic field inside the PM brushless DC (BLDC) electrical machine. Theprototype adopt the inner-rotor structure, magnetization of the permanent magnet (PM) is subsection array parallel form. Furthermore, based on the2D FEA numerical calculation ofthe prototype, the key parameters of the operating conditions for the M/G has been obtained,and to describe each function relation of the key parameters by the curves. To contrast withthe theoretical derivation in the chapter2, verifying the correctness of the control methodunder the specific operating conditions.A new H-type core reluctance multiphase PM BLDC electrical machine has been putforward with the direction of radial and axial are all double design. The new H-type corestructure with multiphase winding becomes redundant multiphase electrical machine. Theaxial two windings can work independently or dependently which has the fault-tolerant ability.The H-type core structure electrical machine is calculated in comprehensive physical field.The efficiency of the PM BLDC electrical machine is a major technical index to examinethe performance of the M/G, then calculating the loss accurately is important to improve theoverall performance of the electrical machine and to research the temperature rise of it. Usingthe FEA numerical calculation method, the stator core loss, the rotor eddy loss and windingcopper loss of the PM BLDC M/G has been calculated under the different operatingconditions. The following has been verified by using the control method that the system losshas been reduced and the efficiency of the M/G has been improved under each operatingconditions. Furthermore, the calculated accurate loss values would act as the heat source inthe transient temperature field, which provide data support for the precise calculation oftemperature field.The temperature rise not only influences on the PM BLDC electrical machine operationperformance, but also influences on the PM BLDC electrical machine’s life time andreliability, so the calculation for temperature field of PM BLDC electrical machine is veryimportant. According to the theory of aerodynamics and heat transfer, the whole region statorand rotor FEM of the3D transient temperature field for PM BLDC electrical machine isestablished in the steady state electromagnetic field, hypothetical conditions and boundaryconditions has been presented in the solved region. The time-variable stator core loss, rotoreddy loss and copper loss thermal resources are presented. Carrying the precise calculation oftemperature field under the motor state, generator state and keep state conditions, whichobtains the highest temperature point among each state. The result can guide the electricalmachine design and supplies the references for the further optimum design or water-coolingdesign of the PM BLDC electrical machine.