Solar pump, otherwise known as PV pump, is the most appealing water supply for sunny areas, and especially those remote and border areas where power is lacking or insufficient. It is easily accessible, endless, automatic, around-the-clock, and unattended, with minimal workload of maintenance. It is a kind of economical, reliable, and environment-friendly ideal green energy system.
PV pumping inverter drives its pumping system by using the electric power delivered by PV array. The whole PV pumping system mainly consists of array, pumping inverter and pump.
PV array is mainly responsible for transforming solar light energy into electric energy and providing electric power for loaded pumping motor.
PV pumping inverter or controller is mainly responsible for controlling and regulating the operation of the pump. The electric power delivered by solar array is used to drive the pump. The real- time output frequency is regulated in line with the changes of sunshine intensity so as to make output horsepower close to the maximal horsepower of the solar cell array.
A pump is a collective mechanical system that is used to lift, convey liquid or charge pressure for liquid, in other words, transforming the mechanical energy of the prime motor into liquid energy so as to pump liquid.
Introduction to pump
Pump is a machine used to transport liquid or charge pressure for liquid. It transports the mechanical energy of prime motor or other energy to liquid to increase the energy of liquid. A pump mainly transports such kinds of liquid as water, oil, acid and alkali, emulsification, suspension-emulsion as well as fluent metal and liquid-gas mixture, and nsuspended solid. The technical parameters of measuring pump performance include flow, suction lift, delivery lift and brake power, water horsepower and efficiency. According to different operating principles, pump can be divided into containment pump, paddle pump. A containment pump uses the changes of the capacity of a workshop to transport energy while a paddle pump uses the interaction between rotating blade and water to transport energy. Besides, there are other types of pump, such as centrifugal pump, axial flow pump and mixed-flow pump. According to control principles, centrifugal pump can be divided into AC pump, brush DC pump, brushless DC motor, isolated magnetic brushless DC pump and three-phase AC pump.
Solar pump, otherwise known as PV pump, is the most appealing water supply for sunny areas, especially those remote and border areas where power is lacking or insufficient. It is easily accessible, endless, automatic, around-the-clock, and unattended, with minimal workload of maintenance. It is a kind of economical, reliable, and environment-friendly high-tech green energy system. Solar pumping system is an optical-electro-mechanical system that has shaped over the past few years. Taking advantage of the electric power emitted by solar cell, a solar pumping system drives direct current, permanent magnetism, brushless, sensorless, and double plastic motor stator and rotor or highly-effective asynchronous dynamo or high-speed switched reluctance motor by following the maximal power point as well as commutation and control equipment to create highly-effective pumping to lift water from the depth of the earth’s surface to the ground for irrigation or drinking. The design and the manufacturing of a solar pumping system need the support of modern technology, such as electricity, mechanics, electric power, electronics, computer and control. The solar pumping system provides an optimal approach to develop modern agriculture, save energy and protect environment. The system has long-term economical efficiency. In particular, compared to the pumping of common diesel engine, the pumping of this new system has overwhelming economical advantage. There is no doubt that the launch of such new environment-friendly, energy-saving product can significantly expedite the development of industry, economy, and especially the development of modern agriculture in arid areas, bringing massive and high economic efficiency and social efficiency. It is an embodiment of the strategy of building an energy-saving and environment-friendly society.
Solar pumping system comprises DC pumping and AC pumping. The driving modes of the DC pumping motor is made up of two major types, namely, brushless AC motor and PMSM( permanent magnetic simultaneous motor).
PV power supply seldom uses motion components and its operation is reliable.
Safe, noise-free, public –hazard-free
It will not produce any solid, liquid or gas or other harmful matter, and therefore it is absolutely environment-friendly.
It is characterized by easy installation, low operation cost, and unattended surveillance. Its high reliability is highly appreciated.
PV electric power generation can collaborate with other energies. Meanwhile, its capacity can be charged conveniently to meet specific demands.
Series-parallel connection of components can meet different needs of power, so it is universally applicable.
Product properties: long life expectancy, low power consumption, low noise, parallel speed regulation, reliable operation and no interference.
It has the features of long life expectancy, unnecessary maintenance, small size, high efficiency, low power consumption, strong anti-interference and smooth operation.
2 It is also carbon-brush-free, non-polluted, electronic-commutated and long-lived.
3 The determinant and the circuit board of motor adopt epoxy potting and are completely segregated from rotator. Therefore, the problem of leakage due to long-term under-water operation of a DC pumping motor can be solved, so that the pump can be installed underwater, with complete water-proof effect.
4 The pumping parameters can be regulated in accordance with customers’ need. A 24V pump can be regulated to have two-meter or seven-meter delivery lift without changing the volume of the pump. Wide-voltage operation is also possible.
5 Since the axis of the pump adopts high performance pottery axle (to lower cost, we can choose stainless axis ), it enjoys high precision, strong resistance to wear. Thanks to the utilization of high precison axile bush and pottery axle (to lower cost, we can choose stainless axis), it produces low noise. Noise with low power can reach below 30dB.
6 The DC pumping driven by a three-phase no Hall program can realize PWM speed regulation, analog signal（0~5V）speed regulation, potential device VR manual speed regulation so as to regulate discharge and delivery lift and customize music fountain
7 The three-phase DC pumping is soft-starting, faultless, with low power consumption. Its circuit board is completely separate from the pump body. The pump body contains no electronic components. The pump body made of high-temperature materials can be used for a long time in water at a temperature up to 100 degrees Celsius. It has the function of protecting blade wheel rotator from being seized, reversed, overloaded, effluence.
8 The pump has diverse interface, such as 4-inch screw thread, 2-inch screw thread, and 8mm or 10 mm or 22 mm, 27 mm turnover. It can be customized too.
9 If pumping delivery lift is to be enlarged, we should carry out series connection, which can amplify delivery lift.
10 It can be used on land and under water( For external application, please install at a place below liquid surface).
11 Pump and relevant control system can be customized.
12 Brush DC solar pump
When the pump works, coil curl and commutator spin while magnet steel and carbon brush do not spin. The alternative changes of the coil curl currents are performed along with the rotating commutator of the motor and electric brush. As long as the motor rotates, carbon brush will produce wear and tear. When computerized pump operates for some time, the space between wear and tear caused by carbon brush will expand, and its sound will amplify too. If the computerized pump has been running for several hundred hours, the carbon brush no longer can perform commutation.
Advantage “ low cost”
13 Brushless DC solar pump( motor-based)
A motor-based brushless DC pump consists of a brushless DC motor and a blade wheel. The axis and the blade wheel of the motor are connected. There is a gap between the determinant and the rotator of the pump. If it has been used for a long time, it is likely that water will penetrate into the motor, and it will possibly incur motor burn-out.
Advantages : now that the manufacturing of brushless DC motor has been standardized, it can be produced in large quantities by professional manufacturers at low cost with high efficiency.
14 Isolated magnetic brushless DC pump
As brushless DC pump adopts the commutation of electric components, it does not need the commutation of carbon brush. It also uses high-performance abrasion-resistant pottery axis and pottery axile bush. Through injection, the axile bush is integrated with magnet and therefore wear and tear can be prevented. As a result, magnetic brushless DC pump has significantly improved its life expectancy. The determinant and the rotator of isolated magnetic brushless DC pump are completely segregated from each other. The determinant and the circuit board are potted with epoxy resin to realize a 100% water-proof effect. The determinant is made of permanent magnet while the pump body is made of environment-friendly materials. In effect, the pump features low noise, small size and stable performance. The wire wrapping of the determinant can be used to regulate various necessary parameters. The pump can run at wide voltage.
Advantages: It has long life expectancy and its noise control can reach below 35dB. So, it can be used for hot-water circulation. The determinant and the circuit board are potted with epoxy resin, and they are completely segregated from each other. Therefore, the pump can be installed underwater and achieve a 100% water-proof effect. The axle center of the pump is made of high-performance pottery axis, and accordingly has high precision and high earthquake resistance.
15 Three-phase AC pump
A three-phase AC pump is driven by three-phase AC motor. Unlike a AC system, a solar AC pump consist of solar array( to supply power), solar pumping inverter ( to switch DC to AC, and control motor frequency`) and three-phase AC motor pump.
The three-phase AC motor pump has high compatibility and therefore it can be substituted with electric or diesel –based AC pump. Meanwhile, AC pump breaks the horsepower limit of DC pump. Horsepower from 150 watt to 105 kilowatt applies to large area of farming land, desert and irrigation
The magnet and the blade wheel of a magnetic brushless DC pump can be injected to form the rotator o the motor. There is axile bush shaped by direct injection in the middle of the rotator. The axile bush is fixed on the capsid through high-performance pottery axis. The determinant and the circuit of the motor are potted into the pump body through epoxy resin. The rotator and the determinant are segregated by a thin wall. Since there is no need of traditional shaft sealing, it is a kind of complete sealing. The torque force of the motor operates through permanent magnetism driven by magnetic field. The permanent magnetism is produced after he coil curl of silicon steel( the determinant) is energized. After the magnet is charged by n level(n=even)`, the magnetic poles mutually form a complete coupling magnetic system. When the magnetic pole of the determinant coil curl and the magnetic pole of the magnet are heterogenous to each other, the displacement angle between the two magnetic polesΦequals zero. At this time, the magnetic energy of the magnetic system is lowest. When the two magnetic poles are homepolar to each other, the displacement angle between the two magnetic polesΦequals 2π/n. At this time, the magnetic energy of the magnetic system is largest. When external force is removed, since the magnetic poles of the magnetic system mutually reject each other, the magnetic force will restore the magnet to a state of lowest magnetic energy. Therefore, the magnet produces motion and drives the rotator to spin.
Thanks to electronic commutation, brushless DC pump does not need carbon brush. Both magnetic rotator and silicon steel( the determinant) have multilevel magnetic fields , so after the magnetic determinant spins at an angle in proportion to the determinant, it will change the direction of the magnetic poles, and makes the rotator always contain peer rejection. In the end, brushless DC magnetic force segregated pump can have relatively higher rotation speed and efficiency.
Since the determinant and the rotator of the magnetic isolation pump are completely segregated from each other, it will completely avoid the liquid leakage problem that exists in traditional motor-based brushless DC pumps. Besides, it can be used underwater and remains water-proof, effectively improving `the life expectance and the performance of `pumps.
When a battery plank absorbs solar radiation, the absorbed direct current is put into solar pumping inverter. The solar pumping inverter switches the inputted direct current to AC and transport the AC to the pump to drive the pump to operate. The solar pumping inverter regulates real time its output frequency according to the change of sunshine intensity to follow up the largest power point and make the best use of solar energy.
A DC pump can make direct use of the direct current produced by a solar plank. However, since the pump itself is a sensitive load, larger starting current is needed. In addition, to make sure that the DC pump can still work even when sunlight wanes, we need a solar control device so as to provide powerful immediate starting current. DC pump is characterized by high efficiency, high rotation speed, high delivery lift, smaller size and higher degree of safety.
The components of a pump
A brushless DC pump( magnetic segregated pump) consists of a pump body( the spacer), electric determinant, axis, axile bush, rotator hydrophyllium ( the magnet and the blade wheel).
Magnet( neodymium-iron-boron permanent magnet)
The magnet made of rare earth permanent magnetic material is an excellent source of magnetic field, for it has a wide range of working temperature(-45－400℃), high coercitive force, fine aeolotropism of magnetic direction. When homopolar magnets get close to each other, it will not cause demagnetization.
When metal isolation sleeve is used, it is placed in a magnetic field of sine alternation. It will induce eddy current on a cross section perpendicular to the magnetic curve, and transform the eddy current into heat. The expression of eddy flow is xxxxx. Pe=eddy flow, K=constant, n=rated rotation speed, T=kinetic moment, F=the internal pressure of isolation sleeve, D= the inner diameter of isolation sleeve, ?= electric resistivity of the material, and ?= the strength of extension of the material. After a pump has been designed, n, T are determined by operating mode. To lower eddy flow, we have to think from the aspects of F and D. If electric resistivity and high-intensity non-metal materials are chosen as spacer, they will have pronounced effect in lowering eddy flow.
A magnetic brushless DC isolation pump is driven to work by electric coil curl’s causing the rotator to spin. Spinning is to keep the rotator working steadily and noise. The combination of high performance pottery axis and axile bush can achieve very high precision and effectively reduce the resistance and the noise of spinning.
The sliding bearing of magnetic pump is made of POM or ceramics. Since POM and ceramics are good at resisting heat, erosion, and abrasion, the sliding bearing of a magnetic pump is usually made by engineering ceramics. As engineering ceramics are crisp and have lower dilation coefficient, the gap between axile bushes should not be too narrow to prevent the accident of suspension bearing
As the sliding bearing of a magnetic pump is lubricated through the conveyed medium, we should consider the conditions of different media and operating modes. We should pay attention to the following items when it comes to choose different materials
1 Prevent the invasion of granule
(1) No iron and magnetic containment, granule should be allowed to invade magnetic driver and bearing friction pair
(2) After we convey those media that are prone to crystallize or deposit, we should promptly flush it to maintain the life expectancy of a sliding bearing. After pumping stops, clear water is added to the chamber of the pump, and after it runs for one minute, we should discharge t it until it is clean.
(3) When we transmit medium containing solid granule, we should filter the medium at the entrance of the flow tube of the pump.
2 Prevent demagnetization( DC pump)
DC pump should be run within prescribed temperature conditions. Medium temperature should not be over-proof. A platinum resistance temperature sensor should be furnished on the exterior surface of a magnetic pump isolator to detect the temperature rise within the annular space. In case temperature is transfinite, the pump should make an alarm or close down. Idle running time should be minimized.