Design And Experimental Research On New Type Of ALA+SPM Combined Rotor Machine

A surface permanent magnet (SPM) machine has the characteristics of high power density, high efficiency and strong overload capacity. The axially-laminated anisotropic (ALA) reluctance machine can achieve a wide constant power speed range (CPSR). Therefore, the ALA+SPM combined rotor machine is expected to obtain the advantages of the SPM rotor machine and the ALA rotor machine, and overcome their shortcomings respectively. However, the performance of ALA+SPM machine is specially affected by both the fraction length of the two-part rotor with a fixed rotor full length and the deflection angle between two-part d-axes. The ALA+SPM combined rotor machine with reasonable designed the two new variables has a good applied prospect in the system of high-quality AC drive. To provide the new type machine with powerful technical support for its application in the near future, the operating performance of the machine is researched deeply in this paper,Based on the development of AC drive system, this paper firstly introduces the study status of the combined rotor machine, and maks a detailed analysis on the operating principles, the rotor structure, electromagnetic relations and mathematical model of the SPM rotor machine and the ALA rotor machine. Then, the basic design rules of the variables k, the fraction length of SPM part, and a, the deflection angle between two part d-axes are researched under the proposed current limit control condition for the safe operation of the combined rotor machine, using the phasor diagram in d-q reference as the tool for analysis of the machine,A 4-pole prototype with the two-part rotor fixed length and adjustable deflection angle was proposed and manufactured for the first time, on which the comprehensive and systematic experimental researches are implemented.Electromagnetic parameters are critical data to assess the performance of a machine. Parameters of the prototype with the different deflection angle are tested in detail. Analysis results indicate that the deflection angle has little influence on d-axis inductance, q-axis inductance and no-load back electromotive force for the combined rotor machine with isotropic PM part (e. g., SPM).The capability of no-load startup is an essential requirement for the application of a machine. The no-load startup performance of the combined machine of the different deflection angle with open-loop VVVF control is discussed. Results show that the combined machine of the reasonable angle a can operate synchronously from standstill to rated speed with inverter power supply, and obtain fast response and strong overload capacity, in accordance with theory analysis.Constant power speed range through field-weakening control is identified as the key technology for a machine to get further development in high speed field. The relevant experiments on combined rotor machine with different a are carried out with the help of sine wave generator set. Experimental results proved that the reasonable a can obtain wider CPSR.Steady operation is the fundamental performance norm. The method to analyze the stability of the combined rotor machine by using the small-signal model is proposed. Conclusions are drawn that the additional mechanical inertia damper on rotor shaft can eliminate or abate systematic oscillation, and improve the stability of the system as well as dynamic performance. Experimental results verify that the method is effective and feasible.