无轴承异步电机磁场定向控制策略分析

针对无轴承异步电机电磁转矩和悬浮力强耦合特性，研究了基于转矩控制绕组气隙磁场定向控制和转子磁场定向控制的无轴承异步电机控制策略，进行了对比分析。分析表明：气隙磁场定向控制中存在最大转矩限制、非线性机械特性，难以实现自适应控制等问题；对转子磁场定向控制而言，当负载或转速变化时，由于转矩控制绕组转矩电流变化将导致气隙磁场发生改变，如果仍以转子磁场近似替代气隙磁场作为悬浮依据，必然影响到悬浮控制性能。文中通过仿真和实验对以上2种控制策略下的系统动、静态性能进行了分析和比较，结果验证了以上所述观点的正确性。

Analysis of Flux-oriented Strategies of Bearingless Asynchronous Motor

In order to realize the decoupling control of electromagnetic torque and radial levitation force in bearingless induction motors, two control strategies are analyzed and compared each other: air-gap flux-oriented control and rotor flux-oriented control. The first control strategy has the disadvantages such as a large amount of computations, inherent pull-out torque, difficulties in realizing the adaptive control and so forth. For the rotor flux-oriented control, changing of load or the rotor speed will result in increased or decreased torque winding currents, which will change the magnetic field distribution in the air gap. Assumption that magnetic field is approximately equal to that generated by torque windings will affect the levitation performances. The steady state and dynamical performances of the system are tested by both simulations and experiments, which verifies the theoretical analysis above.