针对三自由度交直流混合磁轴承和二自由度无轴承同步磁阻电机构成的五自由度无轴承同步磁阻电机,实现磁轴承的径向悬浮力、轴向悬浮力、二自由度无轴承同步磁阻电机的径向悬浮力和电磁转矩的解耦控制是五自由度无轴承同步磁阻电机稳定运行和精确控制的必要条件。该文在介绍五自由度无轴承同步磁阻电机基本结构的基础上,建立了三自由度交直流混合磁轴承和二自由度无轴承同步磁阻电机的数学模型,进而建立了五自由度无轴承同步磁阻电机的状态方程,并进行了可逆性分析。采用最小二乘支持向量机所具有的小样本逼近和辨识拟合能力,得到五自由度无轴承同步磁阻电机逆模型,根据逆系统方法的基本原理,将复杂的原非线性多变量耦合系统解耦成多个单输入单输出伪线性系统,并设计了闭环PID控制器。仿真和实验表明,电机具有良好的速度和悬浮特性,这种解耦方法能够实现五自由度无轴承同步各个被控量之间的动态解耦,并且系统具有良好的动静态性能。
In the paper, aiming at the 5-degree of freedom bearingless synchronous reluctance motor (5-DOF-BSRM), which was composed of a 3-degree of freedom AC-DC hybrid magnetic bearing and a 2-degree of freedom bearingless synchronous reluctance motor, realizing deeoupling control of radial and axial levitation forces of the magnetic bearings, radial levitation forces and electromagnetic torque of the bearingless synchronous reluctance motor was necessary for stable operation and precise control. On the base of introduction of the basic structure of 5-DOF-BSRM, the mathematical model of 3-degree of freedom AC-DC hybrid magnetic bearing and 2-degree of freedom bearingless synchronous reluctance motor were established, then state equations of 5-DOF-BSRM were set up and the reversibility was analyzed. By using the ability of least square support vector machines (LS-SVM) in small sample approximation and identification fitting, the inverse model of 5-DOF-BSRM was obtained. According to the basic principle of inverse system method, the complex nonlinear multivariable system was decoupled into several single input single output (SISO) pseudo-linear systems, and the PID close-loop controllers were designed. The simulation and experiment results show that the motor has good speed tracking and suspension characteristics,this decoupling method can realize dynamical decoupling of each controlled variable in 5-DOF-BSRM, the overall system has good dynamic and static performance.