Design, Analysis And Application Study Of Novel Permanent Magnet Machines

Permanent magnet (PM) machines are a kind of highly efficient energy-saving power units, which have huge development potential. Their use is being increasingly applied in many fields of industry and daily life. Since our government has started to place emphasis on energy reduction and advocate energy reducing techniques, novel PM synchronous machines accord with energy-saving policies for this reason PM synchronous machines are primarily researched and developed in order to provide stable social and economic benefits. Compound permanent magnet synchronous machines (CPMSM) and direct-drive pumping units are put forward for replacing beam pumping units that they are in wide use and their power consumption is the largest on oil fields. The direct-drive pumping unit changes complex cumbersome mechanically-driven mode, and drives the load directly by the CPMSM that has the characteristic of low-speed and huge-torque. So it increases the system efficiency and improves the power factor. The CPMSM increases the output torque per unit volume because it combines one cylindrical outer-rotor electric machine with two disk electric machines in three-dimensional space. In this dissertation, the overall theoretical analysis and experiments of the CPMSM have been accomplished, which include design and calculation method of the CPMSM, electromagnetic field analysis, optimization of structural parameters, reduction of cogging torque, control system research, experiments on the test bed, and application & serialization of the CPMSM in the direct-drive pumping unit.The other kind of PM machine researched in the dissertation is the PM & electromagnetic hybrid excitation linear synchronous machine (HELSM) with internally placed PM, which is put forward for improving the long stator linear synchronous machine (LSM) used in the maglev transportation system. The purpose of researching the novel HELSM is reducing power consumption of the levitation excitation secondary so that the capacity of vehicular power supply and the volume of secondary can be decreased. It is of practical significance.All research work in the dissertation can be summarized in the following items.1. After putting forward the structure of the CPMSM, the electromagnetic parameters calculation methods of the CPMSM came into being, which based on generalizing the design methods and deducing the design formulae of variable-speed PM synchronous machines. The operating characteristic of the CPMSM manifests that the value of stator resistance has great influence on the machine characteristic. The stator resistance results that the power-angle corresponding for the maximal electromagnetic power is less than 90 degree, the stator copper loss is the main portion of the machine gross loss, and the machine efficiency gradually decreases with the load ratio increasing.2. Because of the special structure of the CPMSM, the three-dimensional machine model was designed with the three-dimensional CAD software in order to modifying the model conveniently. Then the planar engineering drawings were drawn with AutoCAD software. In order to ensure reliability of the structure, strength and rigidity of the main shaft were checked applying the theory of mechanics of materials. About temperature rise of the CPMSM, the equivalent thermal loop method was applied in the calculation of temperature rise. Furthermore, the calculation formulae of temperature rise for the CPMSM were deduced. Then the temperature rise of the model machine is calculated and compared with the experimental results. The error percentage is less than 6%.3. After building the analysis model for the CPMSM, the no-load & load magnetic field distribution, the no-load leakage flux, and the output torque under the different power-angle were analyzed and calculated with applying the three-dimensional finite element method of PM machines magnetic field. The measures which can reduce the cogging torque of the cylindrical part and the disk part were discussed respectively with applying the analytical method and the finite element method. In the same way the important structural parameters of the CPMSM were analyzed according to their effect on the machine performance. Therefore the optimal span of these parameters could be ascertained.4. Considering the d-axis and q-axis inductance of the CPMSM are almost equal, the sensorless vector control system of the CPMSM adopts suitable strategy of vector control and sensorless technology that estimates the rotational speed with Extended Kalman Filtering (EKF) algorithm. The primary research work was accomplished in the dissertation, such as designing circuits of the control system, plotting the system block diagram, framing the software flowchart and so on. The control system was analyzed with MATLAB/Simulink simulation software. The simulation results manifest that control effect of the machine control system is ideal.5. The no-load, load, and temperature rise test of the CPMSM were accomplished on the test bed with the novel PM machine measurement system. Then the theoretical calculation results were compared to the experimental data.6. According to the national standard of beam pumping units, the issues about serialization of CPMSM and direct-drive pumping units were discussed in order to replace already existing beam pumping units. The reasons why the direct-drive pumping unit can save energy and increase in yield are explained, and the test data about energy-saving effect are shown in the dissertation. The test data manifest that the same type of direct-drive pumping units can save 50% more energy than beam pumping units which are driven by induction machines.7. For improving on the existent structure of HELSM, two kinds of novel structure of HELSM are put forward, i.e. the incompletely isolated magnetic-field mode and the completely isolated magnetic-field mode with internally placed PM. By comparison of the incompletely isolated magnetic-field mode and the completely isolated magnetic-field mode, it can be seen that leakage flux of the latter is smaller, and its suspension force is larger under the same conditions. So the completely isolated magnetic-field HELSM is the main subject of investigation. The structural parameters of the completely isolated magnetic-field HELSM were optimized with the finite element method of two-dimensional magnetic field. By analyzing the suspension force, the propulsive force, and the no-load leakage coefficient, the completely isolated magnetic-field HELSM was compared with electromagnetic excitation LSM and with two kinds of existent HELSM.The first, third, and seventh items of above research work are the innovative points of the dissertation.