Since the reform and opening up, China's feed industry has made brilliant achievements. In recent ten years, the feed industry has grown at an average rate of around 10% per year. It has developed into an industrial system with relatively complete categories and relatively complete functions, achieving feed production, output value, profits, and taxes. The simultaneous increase in employment. At present, the development of China's feed industry has entered a mature stage, and it is rapidly developing from traditional manual operations to mechanized and automated operations.
This paper presents the application of E-CONVERT EC550 high-performance standard frequency converter to drive feed line feeders.
2, feeding plant automation control process analysis
As the last production link of the feed factory, the batching system is controlled automatically by computer. The different feeds are manually fed to the to-be-crushed warehouse, and then fed to the mill through a feeder. After the crushing, different ingredients are sent. Warehouse storage. Then, the computer controls the opening and closing of each different ingredient door one by one according to the recipe, and after weighing, it is sent to the mixer for mixing, and the fully mixed feed is sent to the granulation bin to be prepared for the last granulation process. Finally, the finished product of the ingredients can be finished after weighing by the ring-shaped granulation mechanism.
Before the transformation, the feeder motor is operated by the power frequency power supply, which has the disadvantages of large starting current, unadjustable speed and the like. The feed rate of the feeder feeding the crusher is proportional to the load of the crusher. Therefore, in order to ensure that the load of the crusher can not be too long to exceed its rated current during the long-term operation of the crusher, most of the control systems use the jog Drive feed: feed the feed motor, add a bit of feed, then stop feeding, then jog the feed motor, add a bit of feed, and then repeatedly switch the motor on and off, so that the shredder current value is not Exceeding its rating within a certain range of fluctuations.
According to the different feeds added, the cycle of the motor switch is not the same. Frequent “jogging†can often not only cause the thermal relay of the feeding motor to trip, the main contactor contacts to burn out, but also to the computer system and the control room. The other instruments produce strong electromagnetic interference and cause malfunctions.
2. Working principle and process
The reconstructed production line is Henan Zhongda's annual feed production line of 100,000 tons of poultry feed. There are eight types of feed produced by the production line: Northeast corn, wheat, soybean meal, peanut meal, rice bran, sub-powder, corn, Bran. The feeds that are most likely to cause feeders to run unstabilized are the corn and the wheat. This is because the density and hardness of the corn are relatively large, and the wheat contains many wheat stalks of different lengths. The feeder is used for the feed crushing system, which consists of a crusher, a feeder and a crusher. The feeder is used to feed the crusher. The motor used is a 1.5kW three-phase asynchronous variable-frequency motor. The power of the crusher motor is 110kW.
China Metallurgical South (Wuhan) Automation Co., Ltd. used a 1.5kW (heavy-duty) EC550 high-performance vector inverter for its feeder motor. Considering that the feeder requires a large starting torque and load torque, this project uses PG-less flux vector control. First of all, use EC550 frequency converter to carry on the electrical parameter recognition, then carries on the PI regulator parameter self-adjustment, finally realizes the parameter on-line self-adjustment function. This function adopts fuzzy control technology to make the inverter have self-learning function during running. The operating parameters can be adjusted according to the real-time status, which can effectively shorten the dynamic response time of the inverter and reduce the overshoot and improve the dynamic performance of the inverter.
After the application of EC550 frequency converter, this process is started from one of the most easily driven feed, bran, into the feeder. According to the production requirements, in order to make the current when the crusher works does not exceed 200A of the rated current of the motor, control the feed. The feed rate should not be too fast. After normal operation, feeds such as soybean meal, groundnut meal, rice bran, and sub-powder are crushed, and the feeder is operating normally. The input feed is also the feed that is most prone to poor feeder operation or stalling - northeast corn, corn, wheat. The torque of the feeder driven by the EC550 can meet the load requirements without affecting the normal operation of the equipment. .
According to different types of feed, EC550 frequency control speed is not the same, the frequency setting range is roughly between 8 ~ 20Hz. Practice has proved that: EC550 inverter can not only provide a larger starting torque, so that the feeder motor can output a larger load torque at low frequency operation, and, after the transformation, the feeder can be set according to the different types of feed The output frequency, the use of variable frequency operation to replace the feed motor "jogging" mode of operation, better make up for the defects before the transformation process to ensure that the current value of the grinder does not exceed its rated value.
At the same time, the maximum torque does not exceed 80% of the rated torque of the motor due to the periodic changes in the load during the feeding and feeding of the feeder. Therefore, the feeder can be operated at a substantially constant speed regardless of input of feed. Even if feeds such as corn or wheat are easily fed to feeds that do not allow the motor to run smoothly, the operation is still very smooth to prevent stalling, which can effectively reduce the current fluctuation range of the grinder and extend the life of the motor.
3. Conclusion
In the transformation of Zhongda University's annual production of 100,000 tons of poultry feed production line, the use of EC550 frequency converter for speed control of the feeder, compared with the control method before the transformation has the following advantages:
1. It replaces the jogging action of the feed motor in the past, and can provide a larger starting torque, output different frequencies to meet the different feed production process requirements, so that the current value of the shredder does not exceed its rated value.
2. The use of variable frequency control reduces the electromagnetic interference to the computer system and related instrumentation caused by the frequent contact and disconnection of the contactor. In practical applications, it is not necessary to take special anti-jamming measures for the computer system, but also to ensure its normal work, thus ensuring the high efficiency of the ingredients and improving the product quality. At the same time, due to the reduced frequent operation of the contactor, the service life is prolonged, and because the interference source is reduced, there is no need to continuously improve the anti-jamming measures in the software and hardware before the system is debugged, thus greatly shortening the system debugging. cycle.
3, using EC550 inverter control, can make the feeder motor output a larger load torque at low frequency operation, when feeding feeds such as corn, wheat, etc., well overcome the original easy to lead to motor operation is not smooth This makes the feeder run more smoothly, thus reducing the fluctuation of the load current of the shredder and making it run more smoothly.
4. Higher user-friendly operation, adopting high-definition LCD operation panel on EC550 can realize switching between Chinese and English display, can display up to three inverter state parameters at the same time, such as: motor speed, output voltage, output current, etc., which is more convenient for users. Visually monitor the status of the motor they are concerned with, and also accurately set the motor's setpoint frequency.
For more solutions, please visit China Metallurgical Southern (Wuhan) Automation Co., Ltd. official website
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