Loom and overstart control method and system thereof

Abstract

A method for control that overstart of loom includes such step as driving permanent magnet synchronous motor (PMSM) by starting voltage to obtain starting torque, wherein the star voltage is higher than the driving voltage corresponding to the running frequency of PMSM, driving the PMSM by starting voltage to obtain starting torque, driving the PMSM by driving the PMSM by starting voltage to obtain starting torque. A linear modulation operation step comprise that following step of: dropping a torque of the permanent magnet synchronous motor from a starting torque to an operation torque after aset period of time by controlling a voltage drive the permanent magnet synchronous motor, wherein the operation torque corresponds to the operation frequency; The permanent magnet synchronous motor is put into linear modulation mode. Accordingly, the invention also provides a loom superstart control system and a loom. The invention adopts the two-phase overmodulation technology, increases the modulation ratio, compensates the amplitude of the fundamental voltage, reduces the switching times of the IGBT, reduces the switching loss, and improves the output voltage of the overstart module to more than 110% in a short time so as to provide a higher output voltage to obtain a larger starting torque.

Description

technical field [0001] The invention relates to the field of looms in the textile and weaving industry, in particular to a loom and its superstart control method and system, especially a water jet loom and its superstart control method and system. Background technique [0002] The existence of driving marks seriously affects the quality of fabrics, and the control of driving marks is one of the important indicators to measure the quality of fabrics, and it is also one of the important indicators to measure the weaving performance of contemporary looms. The running mark is the weaving defect on the cloth surface caused by the loom being stopped and then restarted due to broken warp, weft or other reasons during normal weaving. It is mainly due to the change of the warp tension when the loom is stopped for some reason. The creep or relaxation of the warp yarn causes the position of the cloth fell to move, and the change in the beating force caused by the change in the speed of...

AI Technical Summary

Problems solved by technology

Among them, the switching between different connection methods of the motor requires the use of an AC contactor. The high current brought by the overstart may damage the AC contactor, and the arc generated during the switching process has a safety hazard that may cause the fabric to burn

Moreover, AC asynchronous motors are not easy to adjust the speed. In general looms, the speed of the main shaft can only be changed stepwise by adjusting the pulley, which increases the complexity of the machine and the difficulty of maintenance. More importantly, the starting torque cannot be changed. The same loom faces For different types of fabrics, there will be a phenomenon of thin or dense, and it is very difficult to solve the driving marks by adjusting the machine

When the three-phase asynchronous motor is just started, the slip rate s=1, the rotor leakage reactance is the largest, the power factor of the rotor side is very low (about 0.3), and the active component of the rotor winding current is very small when starting, resulting in high starting current and low torque ;Due to the low power factor of the asynchronous motor, the motor has to absorb a large amount of reactive current from the grid, which reduces the quality factor of the grid and affects the effective use of electric energy; also due to the low efficiency of the asynchronous motor, it is necessary to meet the output power requirements. It is bound to absorb more electric energy from the grid, further increasing the loss of energy and increasing the load on the grid

However, the switched reluctance motor has torque ripple. It can be known from the working principle that the torque generated on the rotor of the switched reluctance motor is superimposed by a series of pulse torques. Due to the influence of the double salient pole structure and the nonlinearity of the magnetic circuit saturation , the resultant torque is not a constant torque, but another harmonic component, which affects the low-speed running performance of the motor, and the rotation cloth angle of the main shaft of the loom is difficult to meet the weaving angle after passing through the 2.5 times reduction ratio. The machine slow-speed weft-seeking positioning accuracy is less than 1 degree; the noise and vibration of the motor drive system are larger than that of ordinary motors

Moreover, the switched reluctance motor and its control part are extremely expensive, and the market acceptance is poor

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