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Metal mine

Case Study

Metal mine

Medium Voltage Variable Frequency Drive Application in Belt Conveyor Syetem

2016-09-18 10:16:09 Bobo HUAFEI Group

Medium Voltage Variable Frequency Drive Application in Belt Conveyor Syetem

ABSTRACT:. This article introduces Jiaozuo huafei product large power medium voltage variable frequency drive of GBP series, and the application in belt conveyor Simply introduces the characteristic of the inverter, load balanced in multi motors drive for belt conveyor, and heavy load start characteristic in low speed.

Keywords: Medium voltage variable frequency drive, Belt conveyor, Multi-motor drive, load balanced, heavy load start in low speed.

1 Introduction

Dexing Copper Jiangxi Copper Company Limited for the expansion of the scale of mining in the abandoned waste rock Tongchang system is broken - conveyor, using two belt conveyors. A mobile belt conveyor, another fixed belt conveyor. After the waste rock crusher, apron feeder by the conveyor belt to the stationary machine. Lose to the mobile belt conveyor. By the mobile belt unloading car on the supreme row Dumping. Discharge capacity of the abandoned mine waste rock system is 2000 tons / year. Dumping Ability to 4500T / H per hour.

Fixed belt conveyor multi-motor drive, a total of four motors, are used Jiaozuo Hua Fei GBP series of medium voltage inverter drive, and start to solve the overloaded Load Balancing belt conveyor belt when the material.

2 Description of the device

2.1 belt conveyor equipment Description:

2.2 inverter motor parameters:

Rated voltage: 6KV Rated current: 182A Rated power: 1600KW Quantity: 4

2.3 Description Drive equipment:

Inverter brands and models: Jiaozuo HuaFei GBP series voltage inverter drive, rated input voltage: 6KV,

Rated output voltage: 0-6KV Rated current: 263A, Rated capacity: 2720KVA,

Overload: 150% for 1 minute, every 10 minutes.

2.4 Conveyor motor map:


Jiaozuo HuaFei GBP series inverter system is structured as follows:

3.1 by the input transformer, inverter unit and control system is composed of three parts. Main circuit topology using multi-level technology series, each phase using five cells in series, a total of 15 three-phase units.

3.2 transformers Class H insulation phase shifting rectifier transformers, high reliability.

Vice-side transformer 3.3 15 low voltage windings, which windings 15, respectively, to 15 units of three-phase power supply.

The main circuit topology principle 3.4 converter is shown below:

3.5 Frequency structural unit of exactly the same, interchangeable. Inverter unit is actually a three-phase input, single phase output 690V low voltage inverter, the switching device is HuaFei Company production of A-level IGBT, temperature rating 150 ℃, thermal protection unit is 100 ℃. High temperature capability is strong, easy to overheat protection. With long-life capacitors, and special attention to the cooling heat capacitance of the capacitor's life expectancy. With a precharge circuit, reducing the high voltage transformer magnetizing inrush current when, by reducing the rectifier diode capacitor charging current moment, reducing the impact of current systems and the grid, but also reduce the impact on the transformer. Internal rectifier diode and extend the life of the capacitor unit.

3.6 The control system uses double-loop speed sensorless vector control, the motor current into the excitation current ID, and the torque current IQ, the field current loop with current ID and the torque current IQ were closed loop control to ensure a constant excitation current, flux stability. Torque current control, it is possible to directly control the dynamic response of the motor torque, torque current millisecond response speed. In the absence of sensor, automatically calculate and detect the motor speed feedback loop with the speed of the closed-loop speed control, speed control and high accuracy. This double-loop vector control, particularly suitable low speed high torque start constant torque load. Such as heavy-duty belt conveyor start, rubber and plastics industry, extruders, mixers, mixer and so on. It can also be multi-motor drive control of the automatic load balancing.

Jiaozuo HuaFei GBP 4 series voltage inverter drive belt multi-machine control Jiaozuo Hua Fei medium voltage inverter drive with belt drive inverter multi-machine control and load balancing and heavy start.

4.1 When the belt machine adopts multiple motors driven simultaneously, using the built-in load balancing drive controller can ensure that the host and from the load balancing machine.

Driver 4 below shows the multi-machine control belt conveyor system, unbalanced load of multi-machine can be controlled at around 1%.

After Dexing Copper strip run, the load is heavy, but the torque current is very balanced. Belt conveyor design throughput of 4500T / H, actually diagram 1964T / H is as follows. Given the speed of 90%, during operation, the torque current of about 35-36%.

# 2 speed motors and other motors have a large deviation. From 1286rpm to 1301rpm, speed deviation reached 15rpm, the speed deviation of 1%. However, the load torque deviation is small, the torque deviation of 34.7% -35.5%, very close to the deviation is less than

1%. Therefore, the main features of this control system is that the speed of each motor can be inconsistent, can be biased. The respective load torque of the motor is relatively close to equilibrium is dynamic, but the load torque variation is small.

When the belt conveyor belt material for some reason stopped, then start belongs to heavy start. Requirements for belt drive can be overloaded with material start. When the belt conveyor in the strip overloaded starting torque of the motor output, that is, to overcome the static friction of the belt below each of the support rollers and roller shaft caused by drag torque, but also to overcome the material on the belt down resistance caused tension moments. Moment of resistance material on the belt caused by the downward pull is constant. But the static friction than the dynamic friction larger, which makes the initial starting torque to overcome the static friction, the resistance than the normal run-time dynamic friction torque caused by a large number. Therefore, the drive must have a low speed high torque start function.

The actual start of the process, because the belt flexibility, each roller is successively selected in order by rotation, rotation is not at the same time. Even if the wheel is rotated up, because the speed is low, the lubrication between the roller and the roller shaft is not good, very astringent, the dynamic friction is unstable, so there is some volatility low torque at start-up. But in the startup process, requires some time to make up for all the rollers are rotated, the torque began to fall. Only up to a certain speed, run

Slippery improved torque fluctuation will be reduced. Therefore, such a large low-speed starting torque, is required to maintain a certain time, typically at least a few seconds. And length and minimum speed start-belt, and the belt scalability and so on. And when you start due to the low speed, torque and speed fluctuations will be relatively large.

Inverter overload capacity of 150% for 1 minute, every 10 minutes. But also improve the current less condition by strong excitation mode, providing even greater than the rated torque and more starting torque, so the starting torque at low speeds especially large, up to 150% -200%. This dynamic high starting torque for a short time, when all the support rollers all turn up, there is no static friction, only the dynamic friction, so the belt driving torque, is smaller than the start, just need to overcome the resistance of gravity moment of the material through the belt tension generated, that is, the drag torque during normal operation. Inverter actual volume has reached 4400T / H (close to the nominal volume 4500T / H) finds it necessary to stop and then start, you can still start the strip overloaded.

The following figure shows the operating data of the belt when overloaded. Design volume of 4500T / H, has actually reached 4400T / H, close to the design limit load current are four motors 138A, not bad. Torque current reaches 73.2% -73.5%, very balanced, the error is 0.3%. But the speed range of 1478-1488rpm. Wherein the host # 4 motor main drive wheel replacement, wheel diameter slightly smaller than the diameter of the other thing, so high speed, and the error is relatively large. Slave speed of 1478rpm, host speed 1488rpm, and deviation of about 10rpm, nearly 0.67%, equivalent to the rated slip of the motor, but the motor current and torque current are very balanced. This is the load balancing control function at work.

The inverter is a double closed loop speed sensorless vector control and closed-loop control the speed of the speed sensor is not required, the inverter output by the excitation current, actual speed automatic detection of motor speed feedback value and use of closed-loop control . And the host is the closed loop speed control, which requires the speed of closed loop response to be fast, so speed feedback before

Can Jinjindegen given, the inverter can be long-term continuous and stable operation with speed in the region of stability, will not enter the stall area stall will not occur, which for low starting torque is very large beneficial. The inverter can also be started with a low speed test, and then run at high speed. You can start using the S-shaped, so that the belt tension changes suffered balanced, belt conveyor start into a soft start, will not suddenly pull off the belt.

5 Conclusion

Jiaozuo HuaFei GBP series of medium voltage inverter drive belt is very suitable for multi-motor drives occasions, load balancing its strong ability to control multi-machine driven, but also has the ability to start large torque, more than from many domestic belt drive performance has proved this point.

references:

[1] Jiaozuo HuaFei GBP series voltage inverter drive commissioning report

[2] Jiaozuo HuaFei GBP series voltage inverter drive User's Manual

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