Application of the hottest Vacon frequency convert

Abstract: This paper introduces the application of Vacon frequency converter in mine hoist in detail. As a special low-frequency power supply, the Vacon frequency converter controls the output voltage according to the requirements of external control signals and the actual running speed, realizing the stable braking and stable crawling of the deceleration section of the high-voltage motor of the mine hoist, while keeping the output frequency unchanged, It has great practical and promotional value

key words: mine hoist low frequency power converter

vacon converter applied to mine lift

li xiaohai

abstract:this paper introduces Vacon Converter Applied to mine lift In this application vacon converter is a special low frequency power supply. The output frequency of the converter is constant. The output voltage will change according to the pre-setting decrease curve and the real speed of the lift in low frequency brake stage. It realizes smooth brake and stabile creeping of the high voltage motor in mine. It has good utility and spread Pro control response slow fit

keywords: mine lift low frequency power supply converter

1. align the two sections of the broken sample at the fracture introduction

the superior braking performance of the mine hoist motor can make the hoist obtain a stable, safe and reliable braking operation state, avoid serious mechanical wear, prevent large mechanical impact, and reduce the workload of mechanical part maintenance, Extend the service life of hoisting machinery. With the automation of the mine hoisting system, improving the performance of the hoisting system, and improving the hoisting capacity of the hoisting equipment, the requirements for the braking of the mine AC high-voltage motor are becoming higher and higher. The traditional braking of mine hoists almost adopts the mode of power braking or low-frequency generator braking. The power braking mode can only solve the braking problem, but can not better solve the problem of crawling. Although the low-frequency generator can better solve the above problems, its whole control system is relatively complex, and there are many equipment used, which brings some inconvenience to the maintenance and overhaul of the system

although ordinary frequency converters can output low frequencies, their system modeling and design are aimed at low-voltage motors, so there is always a certain proportional relationship between their output frequency and output voltage. Therefore, if they are directly used in the low-frequency braking and crawling of mine hoisting motors, it will also cause the output voltage of the frequency converter to be too high and the braking torque to be too large at the beginning of low-frequency input, At this time, the energy fed back to the frequency converter by the power generation state of the motor is also large. If the braking resistance of the frequency converter is not selected properly, it will also cause the danger of overvoltage of the frequency converter. Long term use will cause the DC bridge capacitance of the frequency converter to burn. At the same time, when crawling at a lower frequency, due to its consideration of braking, the torque of the motor during crawling will be small

therefore, according to the actual use requirements of mine hoisting and the open programming platform of Vacon frequency converter of vasa Control System Co., Ltd. in Finland, this paper simulates the operation mode of low-frequency generator system, adopts special software programming, and achieves that in the whole braking and crawling stage, the output frequency of the frequency converter remains unchanged. According to the preset braking curve and the actual running speed, The ideal braking effect is achieved by directly controlling the output voltage of the frequency converter. The low-frequency system with this special software can also output higher voltage when crawling at low frequency, and also takes into account the functions of pedal and rope inspection, which fully meets the requirements of mine hoist. The low-frequency frequency frequency conversion system using this special software has the advantages of reliable system, convenient debugging, simple maintenance and operation, and is of great use and promotion value

2. the control mode of the system

the external wiring of the frequency converter is shown in Figure 1. The input signals of the frequency converter include analog voltage input, forward and reverse signal input, low-frequency voltage output signal, low-frequency crawling signal, foot signal input, and fault reset input

the control mode of the system is divided into closed-loop control and open-loop control. The control block diagram is shown in Figure 2. The actual control mode of the frequency converter will be introduced one by one below

2.1 closed loop control

closed loop control is applied in the low-frequency braking stage. At this time, the analog input signal of the frequency converter is the analog speed signal of the high-voltage motor. One of the forward and reverse signals is closed, the low-frequency voltage output signal is closed, and other signals are disconnected. The frequency converter will convert the value of the analog voltage input signal into the instantaneous speed when the high voltage of the high voltage motor is disconnected according to the closing moment of the low-frequency voltage output signal, as well as the preset deceleration curve slope and braking time to generate the speed curve when the low-frequency braking of the high voltage motor. Under the condition of keeping the frequency unchanged, the output voltage of the frequency converter will be controlled according to the actual speed feedback and the production speed curve, Achieve good braking effect

2.2 open loop control

the open loop control mode is divided into low-frequency crawling, foot brake and foot rope inspection

low frequency crawling mode: low frequency crawling is that after the low frequency braking is completed and the crawling point speed is reached, the low frequency crawling signal is input, the low frequency braking is completed, and the frequency converter outputs according to the preset low frequency voltage

pedal braking mode and pedal Rope Inspection Mode: in these two modes, the output voltage of the frequency converter is proportional to the signal output by the pedal driven self-adjusting machine, and the driver determines the low-frequency voltage that the frequency converter needs to output

3. control principle of low-frequency operation system

the Vacon frequency converter used in this paper has built-in special application macros according to the special requirements of low-frequency braking of hoists. The low-frequency output frequency of the special application software can be directly set on the panel of the frequency converter, and the output voltage of the frequency converter can be automatically adjusted according to the operation of the hoist and the external signal input

during actual operation, when the high voltage of the hoist is input, the forward and reverse operation signals are input according to the running direction of the hoist. At this time, the frequency converter outputs the required low-frequency frequency frequency according to the frequency set on the panel. The low-frequency voltage output is in the "waiting" state, and the output voltage value is 1V left and right. At the same time, the frequency converter records these control systems in real time according to the input value of the analog voltage, including 3 closed-loop control records and monitoring the speed of the high-voltage motor, When the high-voltage is disconnected, the low-frequency output signal is input (dia3 is closed), and the frequency converter will generate a speed curve from the low-frequency braking to the creeping speed of the high-voltage motor according to the speed of the high-voltage motor recorded at this moment