The ten major functions of frequency converter
1. Adjustable torque limit
After frequency control, the corresponding torque limit can be set to protect the machinery from damage, thereby ensuring the continuity of the process and the reliability of the product. The current frequency conversion technology makes not only the torque limit adjustable, but also the torque control accuracy reaching about 3% to 5%. Under the power frequency state, the motor can only be controlled by detecting the current value or thermal protection, but cannot set the precise torque value to operate like in variable frequency control.
2. Controlled stopping method
Just like controllable acceleration, in variable frequency speed regulation, the stopping method can be controlled and has different The stopping method can be selected (deceleration stop, free stop, deceleration stop + DC braking). It can also reduce the impact on mechanical components and motors, thereby making the entire system more reliable and the service life will be increased accordingly.
3. Energy Saving
Using frequency converters for centrifugal fans or water pumps can significantly reduce energy consumption. This has been demonstrated in more than ten years of engineering experience. has been reflected. Since the final energy consumption is cubically proportional to the motor’s speed, the return on investment will be faster after using frequency conversion.
4. Reversible operation control
In inverter control, no additional reversible control device is needed to achieve reversible operation control, and only the output voltage needs to be changed. Phase sequence is enough, which can reduce maintenance costs and save installation space.
5. Reduce mechanical transmission components
Since the current vector control inverter plus synchronous motor can achieve efficient torque output, thereby saving gearboxes and other mechanical transmission components, ultimately forming a direct frequency conversion transmission system. This reduces cost and space and improves stability.
6. The power required at startup is lower
The relationship between motor power, current and voltage If the product is proportional to the product, then the power consumed by the motor started directly through the power frequency will be much higher than the power required for variable frequency start. Under some working conditions, its power distribution system has reached its highest limit, and the surge generated by its direct power frequency starting motor will have a serious impact on other users on the same network, thusWill be warned or even fined by the grid operator. If a frequency converter is used to start and stop the motor, similar problems will not occur.
7. Controllable acceleration function
The variable frequency speed regulation can start at zero speed and accelerate evenly according to the user’s needs, and its acceleration curve You can also choose (straight-line acceleration, S-shaped acceleration or automatic acceleration). When started by power frequency, severe vibration will occur to the motor or connected mechanical parts, shafts or gears. This vibration will further increase mechanical wear and tear and reduce the life of mechanical components and motors. In addition, variable frequency start can also be used in similar filling lines to prevent bottles from tipping over or being damaged.
8. Adjustable operating speed
Using variable frequency speed regulation can optimize the process, and can be quickly changed according to the process, and can also be controlled remotely PLC or other controller to achieve speed changes.
9. Control the starting current of the motor
When the motor is started directly through the power frequency, it will generate 7 to 8 times the rated current of the motor. This current value will greatly increase the electrical stress on the motor windings and generate heat, thereby reducing the life of the motor. The variable frequency speed regulation can start at zero speed and zero voltage (torque boost can also be added appropriately). Once the relationship between frequency and voltage is established, the inverter can drive the load to work in V/F or vector control mode. Using variable frequency speed regulation can fully reduce the starting current and improve the winding endurance. The most direct benefit to the user is that the maintenance cost of the motor will be further reduced and the life of the motor will be increased accordingly.
10. Reduce power line voltage fluctuations
When the motor is started at power frequency, while the current increases sharply, the voltage will also fluctuate significantly and the voltage will drop. The magnitude will depend on the power of the starter motor and the capacity of the distribution network. Voltage drops will cause voltage-sensitive equipment in the same power supply network to malfunction, trip or work abnormally, such as PCs, sensors, proximity switches and contactors, etc., which will all operate incorrectly. After adopting variable frequency speed regulation, since it can gradually start at zero frequency and zero voltage, the voltage drop can be eliminated to the greatest extent.
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