The frequency converter is mainly used to control the power control equipment of the AC motor by changing the operating power frequency of the motor. Do you know the type of inverter? There are two types of frequency converters: carrier specific and general purpose. What’s the difference between them?
There are two main differences between vector-specific and general-purpose inverters, one is high control precision, and the other is large output torque at low speed.
Vector special frequency converter:
The working principle of the vector-specific type is to rectify first, then invert, and then get the frequency and voltage you want.
The vector control technology converts the three-phase system into an M-T two-phase system through coordinate transformation, and decomposes the stator current vector of the AC motor into two DC components (that is, the flux component and the torque component), so as to control the flux and torque components of the AC motor separately. The purpose of the torque, so as to achieve the same good control effect as the DC speed control system.
Vector control is also called ‘speed control’, which can be seen literally.
V/F control mode: Just like when driving, the accelerator opening on the foot is unchanged, and the speed of the vehicle must be changing! Because the road the car is traveling on is uneven, the resistance of the road is also changing, the speed will slow down when going uphill, and the speed will increase when going downhill, right? For the inverter, your frequency setting value is equivalent to the accelerator opening of your foot when driving, and the accelerator opening is fixed when controlling V/F.
Vector control mode: It can control the vehicle to maintain a constant speed and improve the speed control accuracy under changing conditions such as road conditions, resistance, uphill, and downhill.
General frequency converter:
The frequency converter, suitable for all loads, is a universal frequency converter. However, if there is a special type of inverter, it is recommended to use a special type of inverter, a special type of inverter, optimized according to the load characteristics, with the characteristics of simple parameter setting, better speed regulation performance, and energy saving.
The correct selection of the frequency converter is crucial to the normal operation of the control system. When selecting a frequency converter, it is necessary to fully understand the load characteristics driven by the frequency converter. In practice, people often divide production machinery into three types: constant torque load, constant power load, and fan and water pump load.
Constant torque load:
The load torque TL has nothing to do with the speed n, and TL always remains constant or basically constant at any speed. For example, frictional loads such as conveyor belts, mixers and extruders, and potential loads such as cranes and hoists are constant torque loads.
When the frequency converter pulls the load with constant torque, the torque at low speed should be large enough and have enough overload capacity. If low-speed and stable-speed operation is required, the heat dissipation capacity of the standard asynchronous motor should be considered to avoid excessive temperature rise of the motor.
Constant power load:
In the plastic film production line, the torque required by the machine tool spindle, rolling mill, paper machine, coiler, and uncoiler is roughly inversely proportional to the speed, which is called constant power load. The constant power characteristic of the load should be represented by a certain speed variation range. When the speed is very low, due to the limitation of mechanical strength, TL cannot increase infinitely, and becomes a constant torque property at low speed. The constant power area and constant torque area of the load have a great influence on the selection of the transmission scheme. When the motor is in constant magnetic flux speed regulation, the maximum allowable output torque remains unchanged, which belongs to constant torque speed regulation; but in the field weakening speed regulation, the maximum allowable output torque is inversely proportional to the speed, which belongs to constant power speed regulation. If the constant torque and constant power speed regulation range of the motor is consistent with the constant torque and constant power range of the load, that is, in the case of “matching”, the capacity of the motor and the capacity of the inverter are the smallest.
Fan and pump load:
In various fans, water pumps, and oil pumps, with the rotation of the impeller, the resistance generated by air or liquid within a certain speed range is roughly proportional to the second power of the speed n, and as the speed decreases, the speed decreases to the second of the speed. power. The power required by this load is proportional to the cube of the speed. When the required air volume and flow rate decrease, the frequency converter can adjust the air volume and flow rate through speed regulation, which can greatly save electric energy. Since the power required at high speeds increases too rapidly with speed and is proportional to the cube of speed, the load on fans and pumps should generally not exceed the supply frequency.
The frequency converter is mainly used to control the power control equipment of the AC motor by changing the operating power frequency of the motor. Do you know the type of inverter? There are two types of frequency converters: carrier specific and general purpose. What’s the difference between them?
There are two main differences between vector-specific and general-purpose inverters, one is high control precision, and the other is large output torque at low speed.
Vector special frequency converter:
The working principle of the vector-specific type is to rectify first, then invert, and then get the frequency and voltage you want.
The vector control technology converts the three-phase system into an M-T two-phase system through coordinate transformation, and decomposes the stator current vector of the AC motor into two DC components (that is, the flux component and the torque component), so as to control the flux and torque components of the AC motor separately. The purpose of the torque, so as to achieve the same good control effect as the DC speed control system.
Vector control is also called ‘speed control’, which can be seen literally.
V/F control mode: Just like when driving, the accelerator opening on the foot is unchanged, and the speed of the vehicle must be changing! Because the road the car is traveling on is uneven, the resistance of the road is also changing, the speed will slow down when going uphill, and the speed will increase when going downhill, right? For the inverter, your frequency setting value is equivalent to the accelerator opening of your foot when driving, and the accelerator opening is fixed when controlling V/F.
Vector control mode: It can control the vehicle to maintain a constant speed and improve the speed control accuracy under changing conditions such as road conditions, resistance, uphill, and downhill.
General frequency converter:
The frequency converter, suitable for all loads, is a universal frequency converter. However, if there is a special type of inverter, it is recommended to use a special type of inverter, a special type of inverter, optimized according to the load characteristics, with the characteristics of simple parameter setting, better speed regulation performance, and energy saving.
The correct selection of the frequency converter is crucial to the normal operation of the control system. When selecting a frequency converter, it is necessary to fully understand the load characteristics driven by the frequency converter. In practice, people often divide production machinery into three types: constant torque load, constant power load, and fan and water pump load.
Constant torque load:
The load torque TL has nothing to do with the speed n, and TL always remains constant or basically constant at any speed. For example, frictional loads such as conveyor belts, mixers and extruders, and potential loads such as cranes and hoists are constant torque loads.
When the frequency converter pulls the load with constant torque, the torque at low speed should be large enough and have enough overload capacity. If low-speed and stable-speed operation is required, the heat dissipation capacity of the standard asynchronous motor should be considered to avoid excessive temperature rise of the motor.
Constant power load:
In the plastic film production line, the torque required by the machine tool spindle, rolling mill, paper machine, coiler, and uncoiler is roughly inversely proportional to the speed, which is called constant power load. The constant power characteristic of the load should be represented by a certain speed variation range. When the speed is very low, due to the limitation of mechanical strength, TL cannot increase infinitely, and becomes a constant torque property at low speed. The constant power area and constant torque area of the load have a great influence on the selection of the transmission scheme. When the motor is in constant magnetic flux speed regulation, the maximum allowable output torque remains unchanged, which belongs to constant torque speed regulation; but in the field weakening speed regulation, the maximum allowable output torque is inversely proportional to the speed, which belongs to constant power speed regulation. If the constant torque and constant power speed regulation range of the motor is consistent with the constant torque and constant power range of the load, that is, in the case of “matching”, the capacity of the motor and the capacity of the inverter are the smallest.
Fan and pump load:
In various fans, water pumps, and oil pumps, with the rotation of the impeller, the resistance generated by air or liquid within a certain speed range is roughly proportional to the second power of the speed n, and as the speed decreases, the speed decreases to the second of the speed. power. The power required by this load is proportional to the cube of the speed. When the required air volume and flow rate decrease, the frequency converter can adjust the air volume and flow rate through speed regulation, which can greatly save electric energy. Since the power required at high speeds increases too rapidly with speed and is proportional to the cube of speed, the load on fans and pumps should generally not exceed the supply frequency.
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