The correct choice of frequency converter is critical to the normal operation of the control system. When selecting the inverter, you must fully understand the load characteristics driven by the inverter. In practice, people often classify production machines into three types of constant torque loads, constant power loads, and fans and pump loads.
The following article describes the selection techniques for frequency converters:
1 constant torque load:
The load torque TL is independent of the rotation speed n, and the TL is always kept constant or substantially constant at any rotation speed. For example, conveyors, mixers, extruders and other friction-type loads and cranes, hoists and other potential energy loads are constant torque loads.
When the inverter is dragging a load of constant torque, the torque at low speed must be large enough and there is sufficient overload capacity. If you need to run at a low speed and steady speed, you should consider the heat dissipation capability of a standard asynchronous motor to avoid excessive temperature rise of the motor.
2. Constant power load:
The required torque of machine tool spindles and rolling mills, paper machines, coilers in plastic film production lines, and decoiling machines is generally inversely proportional to the rotational speed. This is the so-called constant power load. The constant power property of the load should be in terms of a certain range of speed change. When the speed is very low, TL cannot be infinitely increased due to the limitation of mechanical strength, and it changes to constant torque at low speed. The constant power area and constant torque area of ​​the load have a great influence on the choice of transmission scheme. When the motor is controlled by constant magnetic flux, the maximum permissible output torque is constant and it belongs to constant torque speed regulation. In weak magnetic speed regulation, the maximum allowable output torque is inversely proportional to speed and belongs to constant power speed regulation. If the range of constant torque and constant power speed regulation of the motor is consistent with the constant torque and constant power range of the load, that is, the so-called matching, the capacity of the motor and the capacity of the inverter are all minimized.
3 fan, pump load:
In various fans, pumps, and pumps, as the impeller rotates, the resistance generated by air or liquid within a certain speed range is roughly proportional to the second power of speed n. As the speed decreases, the speed decreases with the second power of the speed. The power required for this load is proportional to the third power of the speed. When the required air volume and flow rate decrease, the frequency converter is used to adjust the speed
The way to adjust the air volume and flow rate can greatly save energy. Because the power required at high speeds increases with the speed, and is proportional to the third power of the speed, the fan and pump load should usually not exceed the power frequency.
Inverters generally fall into four categories: mini, universal, vector, and dedicated.
Mini-inverter: It is more suitable for customers of small equipments. The mini-inverter has exquisite appearance, convenient operation and light weight. Compact design and excellent performance. Obviously, it is suitable for some customers who do small equipment.
General-purpose frequency converter: Full-featured, powerful and stable, suitable for driving conventional loads: For machining equipment, Rhodes fans also need to use versatile inverters.
Vector-type frequency converter: The performance is better than general-purpose frequency converter, suitable for some load inertia, need low frequency and high torque to start (that is, to ensure that the load can be run when the low frequency is running) the situation of the load.
Special-purpose frequency converter: The special-purpose frequency converter is aimed at the appointed trade.
AFSEN can provide different types of inverters, users can choose different types of inverter according to their actual process requirements and application occasions. The Inverson inverter is divided into three major series: AFSV50 mini, AFSV60 standard, and AFSV80 vector type.
(1), AFSV50 mini frequency converter:
AFSV50 Series Technical Specifications
Rated voltage/frequency: 1PH/3PHAC220V50/60HZ; 3PH380V50/60HZ
Output frequency range: 0.1~400HZ
Output frequency accuracy: 0.1HZ
Control method: space vector, V/F control
AFSV50 Series Features
The appearance size of the model is ultra-small, exquisite mini, lightweight and compact design, easy to operate.
AFSV50 series application scope:
Food Machinery Feeders, Blenders, Enrobing Machines, Pastry Making Machines...
Woodworking machinery polishing machine, grinding machine, engraving machine
Textile machinery winding machine, cloth inspection machine
Packaging Machinery Liquid Filling Machine, Pharmaceutical Filling Machine...
Feeding equipment machine, winding machinery, knitting machine equipment
Rubber and plastic industry sealing machine, all kinds of small machinery
Fans, water pump roofs, exhaust fans, small water supply, water jet pumps
Printing equipment six open, eight open offset press
General Commercial General Household Air Conditioning, Automatic Door
(2) AFSV60 universal frequency converter:
AFSV60 Series Technical Specifications
Rated voltage/frequency: 1PH/3PHAC220V50/60HZ; 3PH380V50/60HZ
Output frequency range: 0.10~400.00HZ
Output frequency accuracy: 0.01HZ
Control method: space vector, V/F control
AFSV60 series features: high-performance general-purpose inverter, powerful.
AFSV60 Series Scope of Application:
Air conditioners, greenhouses, refrigerators, fans, pumps, air compressor load conveyors, conveyor belts, cold storage equipment, industrial washing machines, dry cleaning equipment CNC lathes, grinding machines, drilling machines, vertical machining centers, sawing machines, milling machines, engraving machines... ...
Weaving/knitting machinery, bleaching/dyeing machinery, cloth inspecting machine, setting machine, printing machine, winder...
Plastic/rubber processor (injection molding machine, crusher, extruder...)
Bag making machine, hot stamping machine, weaving bag machine... printing equipment. Packaging machines, filling/sealing machines, etc.
(3) AFSV80 vector inverter
AFSV80 Series Technical Specifications
Rated voltage/frequency: 1PH/3PHAC220V47~63HZ; 3PH380V47~63HZ
Output frequency range: 0~600HZ
Output frequency accuracy: Without PG vector control: ±0.5% of the maximum speed (if the set speed is 1000r/min, the speed control accuracy is ±0.5%*1000r/min).
Control mode: No PG vector control (meaning no encoder speed feedback), V/F control
AFSV80 series features: uncompromising quality, perfect performance. When the grid voltage changes, it can automatically keep the output voltage constant.
AFSV80 series application scope:
Papermaking equipment, drawing equipment, injection molding equipment, machine tool equipment;
Chemical fiber equipment, textile equipment;
Screw output device, dyeing and finishing device, air conditioning system;
Boiler system, water supply, oil delivery device, etc.
When selecting the inverter, pay attention to the following points:
1. Select the inverter according to the load characteristics. If the load is a constant torque load, select the AFSV60A inverter. If the load is a fan, the load of the pump should be AFSV60P.
2. When selecting the inverter, the actual motor current value should be used as the basis for the inverter selection. The rated power of the motor can only be used as a reference. In addition, it should fully consider that the inverter output contains higher harmonics, which will cause the power factor and efficiency of the motor to deteriorate. Therefore, comparing the power supply to the motor with the inverter and the power frequency supply, the current of the motor increases by 10% and the temperature rise increases by about 20%. Therefore, when selecting the motor and the frequency converter, consideration should be given to this situation, leaving sufficient margin to prevent excessive temperature rise and affecting the service life of the motor.
3. When the inverter is running a long cable, measures should be taken to suppress the influence of long cable-to-ground coupling capacitance and prevent the inverter from outputting enough power. Therefore, the inverter should amplify the first gear selection or install an output reactor at the output of the inverter.
4. When the inverter is used to control several motors in parallel, it must be considered that the total length of the cable from the inverter to the motor is within the allowable range of the inverter. If it exceeds the specified value, it is necessary to amplify the first or second gear to select the inverter. In addition, in this case, the control mode of the inverter can only be the V/F control mode, and the inverter can not protect the overcurrent and overload protection of the motor. In this case, a fuse should be added to each motor to achieve protection.
5. For some special applications, such as high ambient temperature, high switching frequency, high altitude, etc., this will cause derating of the inverter, and the inverter needs to amplify one gear selection.
3. When using an inverter to control a high-speed motor, high-order harmonics also increase the output current value because of the small reactance of the high-speed motor. Therefore, when selecting the inverter for high-speed motor, it should be slightly larger than the inverter of the ordinary motor.
7. When the inverter is used for pole-changing motor, full attention should be paid to selecting the inverter's capacity so that the maximum rated current is below the inverter's rated output current. In addition, when the pole number is converted during operation, the motor must be stopped first. Otherwise, it will cause the motor to run idle. In bad conditions, the inverter will be damaged.
8. When the explosion-proof motor is driven, the inverter does not have an explosion-proof structure. The inverter should be installed outside the hazardous area.
9. When using an inverter to drive a geared motor, the range of use is limited by the lubrication of the rotating part of the gear. When lubrication oil is lubricated, there is no limit in the low speed range; in the high speed range above the rated speed, there is a risk that the lubricant will run out. Therefore, do not exceed the maximum speed tolerance.
10. When the inverter drives the wound rotor asynchronous motor, most of the existing motors are used.
Winding Motors Compared to ordinary squirrel cage motors, the winding resistance of the winding motor is small. Therefore, the overcurrent trip due to the ripple current is prone to occur. Therefore, a converter slightly larger than the normal capacity should be selected. The general winding motor is mostly used in the occasion where the flywheel moment GD2 is large, and more attention should be paid when setting the acceleration/deceleration time.
11. When the inverter drives the synchronous motor, reduce the output capacity by 10%~20% compared with the industrial frequency power supply. The continuous output current of the inverter is greater than the product of the rated current of the synchronous motor and the standard value of the synchronous pull-in current.
12. For peak loads such as compressors, vibration machines with large torque fluctuations, and hydraulic pumps, if the inverter is selected according to the rated current or power value of the motor, overcurrent protection may occur due to the peak current. Action phenomenon. Therefore, it is necessary to understand the frequency operation and select the inverter with a rated output current greater than its maximum current. When the inverter drives the submersible pump motor, because the rated current of the submersible pump motor is larger than the rated current of the normal motor, when the inverter is selected, the rated current thereof is greater than the rated current of the submersible pump motor.
13. When the frequency converter controls the Roots blower, since its starting current is large, it must be noted whether the capacity of the inverter is large enough when selecting the inverter.
14. When selecting the inverter, be sure to note whether its protection level matches the situation at the site. Otherwise, the dust and water vapor in the site will affect the long-term operation of the inverter.
15. Single-phase motors are not suitable for servo motors, stepper motors, single-phase capacitor motors.
How to reasonably select the frequency converter:
The choice of frequency converter should be considered in accordance with the type of controlled object, speed range, static speed accuracy, starting torque, etc. so that it can be used and economical while meeting the process and production requirements. Because the frequency converter is more expensive, the detailed technical and economic analysis must be done when it is selected. For those devices with high loads and non-different operating conditions, the inverter should not be used.
(1) According to the different types of installation, it can be divided into four types. The appropriate type can be selected according to the power of the controlled motor and the installation conditions at the site. One is a fixed type (wall-mounted type) with a power of less than 37 kW. The second is book type, power from 0.2 to 37 kW, the space is relatively small, can be arranged closely when installed. The third type is the installed/carried-out type, with a power of 45 to 200 kW, which requires additional circuits and an integral fixed housing, which is relatively bulky and takes up relatively large space. The fourth type is the cabinet type, and the control power is 45 to 1500 kW. In addition to the features of installed/carried-out cabinets, it takes up more space.
(2) From the voltage rating of the inverter, there are 1AC230V, also 3AC208 ~ 230V, 380 ~ 460V, 500 ~ 575V, 660 ~ 690V level, should make the correct choice based on requirements.
(3) From the protection level of the inverter, there are IP00 and IP54, and corresponding selections should be made according to the site environment.
The inverter has more brands and types, and the price varies greatly. According to the specific requirements of the process, select brands and types with better performance and relatively lower prices. For this reason, the technical characteristics of the inverter must be understood. The frequency converter can be classified from different aspects.
(4) According to different control methods, it can be divided into general type and engineering type. General-purpose inverters generally adopt a given closed-loop control mode, and the dynamic response speed is relatively slow. When the motor is running at a high speed, it can also satisfy the constant power operation characteristics of the device, but it is difficult to meet the constant power requirement at a low speed. The engineering frequency converter detects the link with automatic compensation and automatic restriction in its interior, and can maintain good characteristics to achieve closed-loop control when the equipment is running at low speed. In the cement plant feeding, unloading, kiln speed and other technological processes, because the control is relatively simple, the requirements are not high, in order to reduce prices and facilitate maintenance, you can choose universal inverter.
Solder For Double Side Pcb,Double Side Welding Wire,Tube Packing Wire Length 4M,Double Sided Pcb Soldering Wire
NINGBO XIHAN TIN SOLDER CO.,LTD. , https://www.soldertop.com