Application of frequency converter in extruder

Extruder, an important plastic machinery, the production and manufacturing of most plastic products can be achieved through extrusion molding.

Common requirements

1. Can perform static self-learning of parameters

2. Use open-loop control without encoder

3. The motor can output 2 times the torque at low frequencies below 3HZ

4.  No loss of step occurs during operation

5. Can read inverter data and display current, speed, and voltage waveforms

Application Advantages

1. Energy saving and high efficiency: The inverter uses constant torque output, which is more energy-saving than other speed regulation methods, especially in low-speed operation.

2. Precise control: The inverter has functions such as automatic overcurrent and overvoltage detection, which can protect the equipment to the maximum extent. At the same time, it has full-frequency high-torque output, fast response, and excellent load adaptability, ensuring the stable operation and efficient production of the equipment.

3. Improve quality: The inverter can suppress sudden current changes and automatically adjust the screw speed, which can effectively avoid quality problems such as broken wires and cavitation in finished products.

4. Protect equipment: The soft start function of the inverter allows the starting current to start from 0, and is limited to the current limit level set by the inverter in the acceleration to the greatest extent, reducing the impact on the power grid and the requirements for the power grid capacity, and extending the service life of the equipment.

Parameter settings

After the wiring of the main circuit and the control circuit is completed, the inverter parameters are set after power-on. The control mode is set to sensorless vector control mode, the operation command is set to keyboard setting, the operation frequency is set according to demand, the acceleration and deceleration time is set to 5 seconds, the motor type is set to synchronous motor, and the motor parameter group is entered according to the motor nameplate parameters. The motor back electromotive force is obtained by estimation. The estimation formula is shown in Note 1. The motor parameter self-learning is set to static self-learning.

Test Results

After the self-learning is completed, the inverter is run and debugged according to the following steps: 

1. Add 100% load under the condition of 15HZ frequency, start and stop and increase and decrease are all stable, the current waveform is normal, the power factor is 0.98, and the inverter output current is more than 40A.

2. Add 150% load under the condition of 10HZ frequency, the inverter output current is more than 70A, and the current waveform is normal.

3. Add 200% load under the condition of 7.5HZ frequency, the inverter output current is 90~100A, and the current waveform is normal.

4. Increase the motor speed to a maximum of 100r/m to test the limit characteristics of the motor, and the current waveform is normal.

5.  Increase the motor load to 1.7 times and 2 times respectively, both at low frequency start and stop below 3Hz, and the inverter output current waveform is normal. Through the above on-site debugging, the requirements of the extruder for the motor output characteristics are fully met.

After being equipped with a frequency converter, the extruder has obvious advantages in significantly improving production efficiency, optimizing energy utilization, enhancing system stability, reducing maintenance costs and improving product quality.

In general, the application of frequency converters in extruders can not only improve production efficiency and save energy, but also reduce maintenance costs and increase the stability and reliability of equipment. It is a new application method worthy of promotion. With the continuous advancement of technology and the continuous optimization of frequency converter performance, it is believed that the application of frequency converters in extruders will be more extensive and in-depth in the future.