Frequency conversion system of rotor of alternating current mine hoist

Abstract

The invention mainly provides a frequency conversion system of a rotor of an alternating current mine hoist. An electromotor rotor winding, a rotor frequency modulation and voltage modulation device (1) and a switch cabinet (2) form a rotor frequency conversion and speed regulation part; a process control part consisting of a master control PLC (Programmable Logic Controller) and an auxiliary control PLC realizes a bi-wiring type of the system control of the mine hoist; an operation platform and a host computer realize the bi-wiring type of the system monitoring of the mine hoist together; a first speed measurement element (7) and a second speed measurement element (8) installed at the end of the spindle of the hoist and a first limit switch (9) or a second limit switch (10) installed in a shaft form a depth and speed detecting part to realize the three-wire type of hoisting position control, data exchange is performed among the master control PLC (3), the auxiliary control PLC (4), a human-computer interface (5) and the rotor frequency modulation and voltage modulation device (1) through a network or a point-to-point communication mode; and the master control PLC (3) and a controlled and detecting element in the hoist are connected through a cable.

Description

technical field [0001] The invention belongs to the frequency conversion control technology of a mine hoist, and mainly proposes a rotor frequency conversion system based on an AC mine hoist rotor frequency modulation and voltage regulation device. Background technique [0002] At present, the speed regulation of the known AC hoist is carried out by changing the metal resistors connected in series outside the rotor of the AC wound asynchronous motor. Before accelerating, all the resistors are connected in series, and then the resistors are cut off step by step. Finally, the hoist runs at the rated speed; in the deceleration stage, the electric braking current (low-frequency current or DC current) must be input and the controllable deceleration can be performed with the cooperation of the external series resistance of the rotor. However, the rotor of this AC wound asynchronous motor is connected in series with resistors for speed regulation, which mainly has the following dis...

AI Technical Summary

Problems solved by technology

However, the rotor of this AC wound asynchronous motor is connected in series with resistors for speed regulation, which mainly has the following disadvantages: 1) It needs dozens of boxes or even more than 200 boxes of metal resistors, which occupies a large area; During the acceleration, deceleration and lowering of heavy objects, a large amount of electric energy is consumed on the resistor, which wastes a lot of energy and does not conform to the national energy saving and emission reduction policy; 3) There is a step-by-step speed regulation, and the speed regulation performance is poor; 4) In the On the stator side of the motor, there are frequent contact reversing and braking current switching, and the reliability of the equipment is not high

[0003] There are two schemes to change the speed regulation method of the external series resistance of the rotor. One: short-circuit the motor rotor winding at the outlet terminal, and use a high-voltage frequency converter on the stator side to control the motor and adjust the speed. However, this high-voltage The frequency converter is composed of three groups of multiple low-voltage variable frequency power units connected in series. The number of power units is usually 3X6 (6KV) or 3X9 (10KV). The number of power units is the same), the hardware and manufacturing process are complex, and there are many potential fault points, large volume, and high cost compared with low-voltage frequency converters; second: short-circuit the stator winding of the motor at the outlet terminal, and use The low-voltage frequency converter whose output voltage matches the rated voltage of the rotor—the AC mine hoist rotor frequency and voltage regulation device controls and speeds the motor. , invention patent application number: CN200810141371.6) discloses that this rotor frequency modulation and voltage regulation device is characterized in that: the input is the standard power supply voltage stipulated by the state such as 380V, 660V, 1140V, 3KV, 6KV, 10KV, and the rated voltage of the output is the same as that of the motor The rated voltage of the rotor matches. Although there is no unified standard for the rated rotor voltage of the motor (the rated voltage of the rotor winding is different for different models of motors from different manufacturers), but the rated voltage of most rotors is less than 1140V. In other words, This solution uses low-voltage frequency conversion to solve the problems that can only be solved by high-voltage frequency converters. The hardware is simple and reliable, and the cost is low. From a practical point of view, the use effect is comparable to that of high-voltage frequency converters.

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