Stable Operation Control Of Hoisting System Driven By Segment Winding Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor(PMLSM) combining the advantages of permanent magnet motor and linear motor, is one of the best driving sources for ropeless hoisting system and is expected to have a wide range of application in the ultra-high building, ultra-deep mine and aircraft-carrier elevator. For long distance moving PMLSM, the stator windings usually select segmental structure. The segment winding PMLSM(SW-PMLSM), whose primary winding is divided into sections with only one unit iron core, can install conveniently, save energy, and improve the efficiency.SW-PMLSM stator armature windings select sectional power supply method. Along with the movement of mover, the magnetic circuit structure of each section primary winding is changed which causes the electromagnetic parameters changing and lead to thrust fluctuation. For vertical moving SW-PMLSM, windings switching failure may cause the motor out-of-step and affect the stable operation. The paper carries out research on stable operation control of hoisting system driven by SW-PMLSM.By use of electromagnetic field theory and layered equivalent model, the finite element method(FEM) of U-type PMLSM is constructed, the related simulation is carried out and the magnetic flux lines, flux density, back Electromotive Force(EMF),cogging force and thrust power angle characteristic are obtained. According to the mover position, the motor model is classified into two kinds, one is the area with the mover, and the other is the area without the mover. The flux density expression is obtained with the mover in different positions. The self inductance, mutual inductance of U-type PMLSM are derived, and the relationships the mover position are acquired.The back EMF expression is derived, and the relationship with mover position is obtained. Based on the back EMF expression, the influence of entry and exit effect of thrust is derived. The mathematic models of U-type PMLSM when the permanent magnet mover fully couples with the stator windings, doesn’t couple with windings, is entering or leaving the windings are constructed.Criterion of static stability for SW-PMLSM hoisting system is proposed, the transient stability equal area rule is obtained. Based on the equivalent circuit of PMLSM,the thrust expression is derived. Through the research on low speed PMLSM thrustpower angle characteristic, the effect of frequency, voltage and windings switching failure fault on thrust power angle are obtained. Based on the Lyapunov’s stability of motion definition and linear stability judging method for nonlinear system, the smallsignal equations of the SW-PMLSM hoisting system is derived. The criterion of static stability is proposed and the stable region and its boundary are obtained. Based on the relative kinetic energy method, the transient stability equal area rule of SW-PMLSM hoisting system is proposed. The conditions that SW-PMLSM hoisting system transient stable need to meet are obtained. The operation performance and the transient stability of windings switches failure simulation are carried out. The research results set a foundation for the SW-PMLSM hoisting system stable operation control.The winding switching tolerant control method of SW-PMLSM hoisting system is proposed. The fault models of position sensor and winding switching actuator are constructed. Through the analysis of the fault signals, a diagnostic method that detected the jumping edge sequences of position signals and calculated the distance between the adjacent edges of position signals is researched.Fault-tolerant control is carried out by taking advantage of the age relations of position signals. A winding switching faulttolerant control method by adjusting thrust power angle on line is proposed. When the windings switching failure, according to the fault type and operating frequency, the controller increases the output voltage of inverter to improves the thrust of residual motors and ensure the SW-PMLSM hoisting system operating stable.The distributed power supply method of SW-PMLSM hoisting system based on field bus is proposed. The safety protection system, signal detection and processing system and PLC control system are designed. The experiment platform is built and the experiments of dynamic braking, windings switching failure characteristics and windings switching fault-tolerant control are carried out. The experimental results agree well with theoretical analysis and simulation and experimental results.