Advanced Materials Research Vols. 614-615

Abstract: This paper deals with the main magnetic field distribution for a three-phase five-column disintegration transformer with the iron core disassembled into several parts owing to limited transport condition. The finite element method is employed to solve such a special configuration transformer, in which the direct field-circuit coupling formulation is derived and programmed by APDL programming language. The calculation results, such as the magnetic field distribution in transformer core, the exciting current magnitude and no-load loss are investigated. The optimum size of air gap between each separated iron core limbs is discussed.

Abstract: Aiming at analyzing the influence to ceramic electric spindle and metal electric spindle caused by carrier ratio in frequency converter, in this paper, the time-step finite element model was built based on SPWM method. The changing law of the loss in different carrier ratios were gained by simulation. The result shows that the greatest impact by carrier ratio is solid loss, the least is core loss. The ceramic electric spindle is less impact by carrier ratio than metal electric spindle. Additionally, the corresponding carrier ratio with minimum loss in both ceramic electric spindle and metal electric spindle were found.

Abstract: This paper presents the development of a new induced excitation system in the synchronous generator. The induced excitation system is a relatively new type of brushless and exciterless machine, which offers an excellent balance between cost, reliability, power density, and high-speed capability. Aiming at the low efficiency problem of the construction of excitation system, this paper presents an improved construction method for excitation system. The result showed that it has superiority in effect.

Abstract: The high-voltage general inverter which has the advantage of the structure， has become the key equipment to saving energy in recent years. The inverter output current is the key variable of overload protection, over current protection and V/F control compensation, so the real-time accurate measurement of its RMS is extremely important. In this paper, the output current signals preprocess by hardware filter firstly, and then find the RMS of the current signal in the period of the waveform. Meanwhile, this algorithm belong to true RMS algorithm category, which suitable for testing harmonic current signal, and can avoid mean filter to reduce the computation time. By using this algorithm, the inverter control system provides accurate reference for overload protection reduces the systematic disoperation rate and sets the more accurate security allowance to ensure the safe operation of equipment.

Abstract: Many reliable energy conversion methods are constantly being sought for renewable energy applications. The permanent magnet induction generator is a new concept which uses permanent magnets to provide the flux in the machine. This will lead to an improved power factor and higher efficiency. This type of generator is a very attractive renewable solution. In this paper ,firstly,introduce the structure and principle of permanent magnet induction generator. Secondly, the dynamic starting performance of this machine is studied. Finally, finite element analysis and simulation are carried out, the results verify the performance of the machine meet the design requirements.

Abstract: In this paper, the single-phase operation of a line start permanent magnet synchronous motor (LSPMSM) has been analyzed in detail. At first, based on symmetrical component method, the condition for balanced operation is derived. Secondly, steady state performances are analyzed by computer programming. Thirdly, the transient performances are studied on the basis of MTLAB/Simulink. The results demonstrated that the LSPMSM running on a single-phase supply has lower efficiency but higher power factor than three-phase balanced operation, besides good starting and operating performances can be achieved.

Abstract: The permanent magnet synchronous motor take place under certain conditions chaotic phenomenon, according to the differential geometry theory, using the method of linear completely accurate, to design the control chaotic control law, and then through the experiments to verify its validity.

Abstract: The six-phase permanent magnet synchronous motor (PMSM) is designed with two sets of Y-connected windings phase shifted by 30 electrical degrees. Two mathematic models of six-phase PMSM are established by different methods, which are based on dual d-q transformation and decoupling vector space respectively. By the dual d-q transformation, the electromagnetic torque is calculated based on the two sets of Y-connected windings separately. By the decoupling vector transformation, extra vector subspace is established, in which the current components have no effect on the electromagnetic torque. According to the different models, two vector control systems for six-phase PMSM are presented. The relationship and equivalence of the two control methods are indicated through comparison analysis and open-loop simulation. And the closed-loop simulation and experiment results show that the two methods have consistent control performance

Abstract: The piston stopping position after engine shutdown is the key factor for idling stop technology, the next starting process of the engine is decided by the piston position. The piston stop position detecting system is designed based on the gasoline direction injection 4G15. The system is composed of a high-speed data acquisition card, two optical sensors, an encoder, a cylinder pressure sensor, an amplifying circuit and an industrial computer. The state signals of the crankshaft and the camshaft are collected by the detecting system, the distribution probability of piston position is obtained. The crankshaft reversal after shutdown and the crankshaft position can be detected and judged.

Abstract: 920 nm optically pumped semiconductor vertical external-cavity surface emitting laser (OPS-VECSEL) has an important application in laser display. We constructed and optimized a 920 nm OPS-VECSEL with active region of In0.09Ga0.91As quantum well (QW) system pumped by 808 nm laser diode module. By the finite element method, self-consistent solutions of the semiconductor electronic and optical equations are realized to calculate the characteristics parameters of OPS-VECSEL. The performances of device especially the mode, the threshold and the optical-optical translation efficiency were analyzed by dealing with different number of QWs (1, 2 and 3) in one period, QW depth, barrier width, the component and dimension of the non-absorption layer. We chose an improved structure of them. On this basis, we ameliorated the number of QW periods and the simulation showed that in order to obtain high performance device, the choice of the number of QW periods must be cautious.