Research on a unistor equivalent circuit of linear induction motor and its parameter estimation.

通过对基于虚元单元的线性感应电动机三相等效电路的分析，得出了以下几点结论。(1)在驱动条件下，三相LIM各端输入电压和电流不平衡。造成这种现象的原因是LIM的末端效应。因此，LIM应该用具有4个端子的三相等效电路来表示，而不是用单相等效电路来表示。(2)由于LIM的影响，气隙中的磁分布随二次导体速度的变化而变化。等效电路上的铁损等参数是速度的函数。因此，电路参数的确定应在驱动条件下进行。(3)利用复功率矩阵估计功率的分布。根据功率矩阵，功率在LIM和源的各个相位通常是不平衡的。(4)估计了各相二次电阻瞬时的二次功率。这种瞬时的二次功率产生推力脉动。由于推力脉动与垂直输送机械系统产生共振是十分危险的，因此如何减小推力脉动是目前最需要解决的问题。(5)推导出脉动系数K_C和K_S，并根据瞬时二次功率方程估算出脉动系数K_C和K_S。通过对垂直驱动系统中圆柱形LIM的测量，验证了上述方法的正确性。

By analyzing a 3-phase equivalent ciercuit of linear induction motor (LIM) based on an imaginary element unistor, investigators made the following points clear.(1) Input voltage and current on each terminal of 3-phase LIM are unbalanced under the driving condition. The cause of this phenomenon comes from the end effect of LIM.Therefore LIM should be represented by a 3-phase equivalent circuit with 4 terminals, not by a single phase equivalent circuit.(2) By reason of the effect of LIM,magnetic distribution in the air gap changes with velocity of secondary conductor. The iron loss and other parameters on the equivalent circuit are the functions of velocity. Therefore the determination of circuit parameters should be done under the driving condition.(3) The distribution of power was estimated by the complex power matrix. According to the power matrix, the power is usually unbalanced in each phase of LIM and source.(4) The instantaneous secondary power on the secondary resistance in each phase was estimated. This instantaneous secondary power produces the thrust ripple. As the thrust ripple is dangerous if it resonate with mechanical system of the vertical transportation, the decrease of ripple is the most problem to solve today.(5) Ripple coefficients K_C and K_S were induced and estimated from the equations of instantaneous secondary power. They were verified by the measurement of cylindrical LIM in vertical driving system.