The need for variable frequency drive permanent magnet synchronous motors for applications on pumps and other equipment

Update:18-04-2019
Summary:

In all aspects of industrial and agricultural productio […]

In all aspects of industrial and agricultural production and life, the application of pumps can be seen everywhere. Pumps are also used in many equipments. The energy consumption of pumps is second only to the energy consumption of power motors, and it is a large energy consumer. Under the current severe situation of energy conservation and emission reduction, reducing the energy consumption of pumps is of great significance for energy conservation and emission reduction. The pump mainly includes a centrifugal pump, a vortex pump, a mixed flow pump, an axial flow pump and the like. The impellers of various pumps are on the motor shaft in the pump body. The motor rotates to work to lift the liquid, and the motor is the most important part of the pump. The motor of the pump is usually a single-phase asynchronous motor and a three-phase asynchronous motor, and is an induction motor. . The application of permanent magnet synchronous motor to equipment power has been a matter of the past ten years. At present, there are common numerical control milling machines equipped with position encoders, servo motors for lathes, and permanent magnet synchronous motors for injection molding machines. The servo motor that requires precise position positioning is used on the machine tool. The main consideration is the functional aspect, and the permanent magnet synchronous motor used in the injection molding machine is mainly installed for energy saving and efficiency. The application of permanent magnet synchronous motors in other equipment is still relatively rare. The permanent magnet synchronous motor produced by our company is applied to the pump.

 

 

The permanent magnet synchronous motor needs a matching frequency conversion controller, which is different from the ordinary vector frequency converter. It is a DC frequency conversion technology, and adopts the latest technology such as mode control theory, adaptive technology, closed-loop control technology and the like without Hall DC brushless motor control. It can work in constant power, constant speed, constant torque and other working modes. It has the characteristics of fast response and precise control. It has flat output power curve in the whole power load section and high efficiency in all aspects of motor efficiency. It is beyond the reach of other motors. The permanent magnet synchronous motor has high efficiency and is much more efficient than the asynchronous motor of common power. It is 15-20% more efficient than single-phase asynchronous motor (permanent magnet synchronous motor with variable frequency controller loss), which is asynchronous than three-phase. The efficiency of the motor is 7-10% higher. If the three-phase asynchronous motor is also equipped with variable frequency control, the efficiency will be 11-15% higher. See the motor load characteristics table.

 

 

In addition to the characteristics of the pump structure, the efficiency of the pump is mainly the efficiency of the motor. The efficient motor is used as the pump power, and the efficiency of the pump unit is high. The pump efficiency is generally 50-70%. If a permanent magnet synchronous motor with 10% higher efficiency than the asynchronous motor is selected, the unit efficiency of the pump can be increased by 5-7%. Another characteristic of permanent magnet synchronous motor is that the higher the speed, the more obvious the advantage. Its speed can be designed according to requirements. When the speed is high, the motor is small in size, less in consumables, and the cost per unit of power is low. The speed of a common asynchronous motor is determined by the number of poles. It is usually 2 or 4 poles. When the speed of an asynchronous motor is 50 Hz, the maximum operating speed of the 2 poles will not exceed 2900 rpm. The design of the impeller of the pump can only be designed according to this speed. . If the speed is increased again, the vector inverter is used to increase the speed of the AC asynchronous motor. However, the volumetric weight of the variable frequency asynchronous motor is still small, and the efficiency cannot be improved. It is impossible to compare with the excellent performance of the synchronous motor. According to the principle of fluid mechanics, the centrifugal pump, vortex pump, mixed flow pump, axial flow pump and other leaf pumps can increase the speed and increase the head and flow. The flow rate is the power of the multiple of the speed increase, and the lift is twice the speed increase multiple. Fang, it can be seen that increasing the speed has a significant effect on improving the head and flow of the pump, which is beneficial to improving the performance of the pump, while the high-speed permanent magnet synchronous motor is lower in volume than the low-speed conventional-speed permanent magnet synchronous motor. More advantages, but also have an advantage in performance. Increasing the speed has played a positive role in these two aspects. How high is this speed? According to the material process, it is generally suitable to choose 4,000 to 7000 rpm, if the key materials such as seals, bearings, shafts, impellers, etc. Solve well, especially the impeller, rotor, shaft, etc. are well made, high concentricity, stable and non-vibrating at high speed, so that the speed can be selected higher, such as 10,000 rpm, the performance of this pump occurs. The qualitative change is a new high-tech pump product. These are updated through equipment, and the processing technology is corrected, which can be achieved through routine efforts. The permanent magnet synchronous motor is equipped with a DC frequency conversion technology controller, which has various automatic protection functions such as overheating, overcurrent and overload.

 

 

The constant speed function of the synchronous motor enables the pump to keep the flow and head constant when the grid voltage changes, and can maintain a good stability when working with a wide voltage. The core of the digital processing circuit of the controller is a single-chip microcomputer, which can set various program instructions according to the working needs of the pump. It can be constant current, constant pressure water supply, water level control, timed power-on and shutdown, and can communicate with the computer host and connect to the office. Remote control of the desktop and remote control of the network enable intelligent and automated pumps. After the high-speed permanent magnet synchronous motor is equipped with centrifugal pump, vortex pump, mixed flow pump, axial flow pump and other pumps, the flow head and efficiency of the pump will change greatly, the lift and flow will be greatly improved, the electromechanical integration is small, and the volume is small. Light weight. Permanent magnet synchronous motors are gradually applied to various types of pumps, which will bring an industrial technological revolution to the pump industry, promote the energy saving and emission reduction of the pump industry to a higher level, and improve the energy saving effect of the entire pump industry and even the whole country by 10%. Row work has a very significant meaning. Since last year, we have done a detailed test in the pump industry's first market-based company, Leo Pump, to replace the ordinary three-phase asynchronous motor with a permanent magnet synchronous motor. A 10 multi-stage pump with 10 wheels and 4 impellers and 1.5 kW. Replace with our 5000-rpm synchronous motor, the speed is increased by 5000/2850=1.7544 times, the lift is the square of the multiple of the speed increase, 1.7544*1.7544=3.08 times, the flow rate is one time, so the flow rate is increased by 1.7 times, the pump unit The efficiency has increased to 62.8%, which is nearly 10 points higher than the original motor efficiency, and the efficiency of the pump unit is increased by 7 percentage points, achieving a very significant energy saving effect.

 

 

In the same way, we used the permanent magnet synchronous motor in Hangzhou to replace the three-phase asynchronous motor of each frame number, and achieved good results. The experiment proves that the pump uses permanent magnet synchronous motor instead of three-phase asynchronous motor. After that, at the same speed of 3000 rpm, the synchronous motor of the same base is 2.5 times the power of the three-phase different motor. At 4000 rpm, it is 4 times larger than the asynchronous motor of the same base. The motor efficiency is in line with GB/ The second level of T30253-2013 is close to the standard of level 1. After the speed is properly increased to 4000 rpm, the pump body is shortened by half, saving material and reducing costs. Because our pump is equipped with a permanent magnet synchronous motor with more than a dozen patents, cooperation with us is an inevitable choice for pump companies. At present, there are many pumps in contact with our supporting motors, and they are well-known pumps in the industry. Enterprise, we believe that not long after, the application of our permanent magnet synchronous motor in the pump industry will be fully developed, and the development of our company will start a fast lane. In the field of general-purpose equipment motors, more and more inverter control is needed now, such as hydraulic machinery, CNC machine tools, air compressors, etc., which require general-purpose synchronous motors. We now produce general-purpose synchronous motors that can meet the transformation of equipment in these industries. The replacement of general-purpose equipment motors with permanent magnet synchronous motors is an urgent need for industrial automation. At present, many companies, such as Fujian, Fujian, and Fujian, have contacted us to replace the original asynchronous motor with our permanent magnet synchronous motor.

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