KR20080015403A - Control system for a pump - Google Patents

Abstract

The present invention relates to pumps comprising variable frequency drive means and methods for operating such pumps. The inventive method for operating a pump (1) comprises the steps of, obtaining values of operating parameters of the pump (1) indicating pump conditions, communicating said values of operating parameters from variable frequency drive means (2) to a control device (11), determining if a predetermined condition is ful-filled, communicating instructions from the control device (11) to the variable frequency drive means (2), based on the fulfilment of said predetermined condition. Furthermore, a computer program product loadable into a memory of a digital computer device, including software code portions for performing the inventive method, a pump (1), a pump system and a control device (11) for a pump are described.

Description

Control system for pumps {CONTROL SYSTEM FOR A PUMP}

The present invention relates generally to a pump, and more particularly the present invention relates to a pump comprising variable frequency drive means. The invention also relates to a method for operating such a pump.

Submersible pumps as well as pumps comprising variable frequency drive means, such as sewage pumps, drain pumps, and dewatering pumps, are used in mining shafts, wells, for example in construction sites or other applications. It is commonly used to pump fluids in mining applications such as wells. Typically, submersible pumps are submerged in whole or in part for extended periods of time while in operation and off-state.

A problem that is often encountered in pumps, in particular submersible pumps, is a so-called snoring operation, which means that the pump partially absorbs liquid and air. This is due to the fact that the liquid level drops below the required level of the pump and the pump begins to partially absorb air. From this moment the pump is no longer productive and uses energy unnecessarily. Water silts remain in the mining shafts or wells and particles accumulate in the pump's hydraulic machine. As long as the pump is in this snoring state, these particles remain in the hydraulic machine to further wear the impeller, suction cover, seals and the like. This inefficient pumping significantly increases the overall operating cost of the pump. This snowing operation may also damage the pump motor due to overheating. In certain applications, to overcome this snoring problem, sensors such as level switches are used to sense fluid levels in the wells. However, such a level sensor may be blocked or undergo a level shift, for example due to a collision with a substance in the fluid, such as a twig, and in that case it will signal an error.

US 6,481,973 to Struthers discloses a pump system that solves some of the above problems. This pump system includes variable frequency drive means, but as a complement to the level switch, uses another control method to detect whether the liquid level falls below a predetermined level. More precisely, this pump system detects whether the speed of the motor suddenly increases or the motor torque drops abruptly. The operation of such a motor is monitored by a sensor connected to an AC output link extending from the variable frequency drive means to the motor. However, this pump system has a big disadvantage. If the increase in motor speed is slow, this pump system may not be aware of changes such as an indication of the dry running of the pump. In other cases, the pump system does not detect whether the water level is high enough for pump operation at start-up of the pump, because in this state there cannot be a sudden increase in motor speed or a sudden drop in motor torque. Thereby, the pump will run for a considerable time until it is switched off due to overheating, so there is a risk of serious damage.

In many applications as described above, the pump operates in a dynamic environment and therefore must be able to operate effectively over a wide range of head / tempertures. The pump head corresponding to the pump height may use a given power to raise a given amount of liquid, for example a given amount of water, see FIG. 3 where a typical pump curve is indicated by line 30. do it. The utilization of pump power can be reduced at low flow Q. Therefore, it is advantageous for the pump to be able to pump with high (or increased) utilization of pump power even at low flows.

Another problem that frequently occurs, especially when the pump is in the off-state for a very long time, is the clogging of the inlet and / or the impeller, which settles in the inlet and the impeller, causing the silt to have a relatively coarse or solid consistency. It is mainly caused by particles in the fluid. This in turn entails that a large starting torque of the pump motor is required to start the rotation of the pump impeller. The maximum starting torque is required to start the rotation and the motor must run at the maximum torque for a significant period of time. This consumes a large amount of energy and also wears the pump impeller and motor. Even when the pump is off-state for a long time, even the maximum starting torque may not be sufficient, in which case the pump must be cleaned manually. The pump may also be blocked during operation, for example by particles sucked into the impeller. Therefore, the reliability of the pump operating in this environment is low.

The pump system described above according to US Pat. No. 6,481,973 to Struthers also solves this problem as well. However, this method causes the motor to continue to malfunction even if the pump is determined to be clogged. More precisely, if an unacceptably high motor torque is detected at a given speed of the motor, the pump system will slow down the motor and increase the level of acceptable motor torque. The purpose is to obtain a stronger pump that can overcome the strength of solid materials, but stronger motors combined with hard contaminants can damage impellers, impeller seats, pump housings, and the like.

Another known problem with pumps including conventional variable frequency drive means is that they are mounted far from the pump in a dry location, typically above ground. More precisely, this requires a long power cable from the variable frequency drive means to the motor of the pump, which can cause serious problems due to electromagnetic interference in conventional variable frequency drive means. In US Pat. No. 6,481,973 to Struthers, the variable frequency drive means is mounted in a pump case, more precisely on a plate connected to a motor. In this case, however, the operation of the variable frequency drive means is adversely affected by the heat emitted from the motor, thereby causing a malfunction of the variable frequency drive means.

Therefore, there is a need for improved pumps and improved control methods for effectively controlling such pumps in terms of energy consumption and durability of the pumps.

It is therefore an object of the present invention to provide an improved pump, a pump system comprising such a pump, a computer program, a control device for such a pump, and a method for effectively controlling such a pump and the pump system with respect to pump capabilities in various pump heads. It is.

Another object of the present invention is to provide an improved pump, a pump system including such a pump, a computer program, a control device for such a pump, and a method for effectively controlling such a pump and the pump system with respect to energy consumption.

Another object of the present invention is to provide an improved pump, a pump system including such a pump, a computer program, a control device for such a pump, and a method for effectively controlling such a pump and the pump system with respect to the durability of the pump. .

It is another object of the present invention to provide an improved pump, a pump system comprising such a pump, a computer program, a control device for such a pump, and a method for controlling such a pump and a pump system in such a manner as to reduce wear and increase the pump life of the pump. To provide.

It is another object of the present invention to provide an improved pump, a pump system comprising such a pump, a computer program, a control device for such a pump, and a method for controlling such a pump and the pump system in an environmentally friendly manner.

It is another object of the present invention to effectively provide for improved pumps, pump systems including such pumps, computer programs, control devices for such pumps, and reliability at startup as well as reliability during operation of such pumps and pump systems. It is to provide a method for controlling.

These and other objects according to the invention are achieved by providing an improved pump, a pump system comprising such a pump, a computer program, and a method for controlling such pumps and pump systems with the features defined in the independent claims.

In the context of the present invention, "pump speed" is defined as the number of revolutions per unit of time of the pump.

According to a first aspect of the invention there is provided a method of operating a pump, said pump comprising a motor and variable frequency drive means, said variable frequency drive means being connected to a feeder cable of said motor and pump. And control the operation of the motor, including a rectifier, an inverter and a DC link extending between the rectifier and the inverter, wherein the pump is operably connected to a control device. The pump operation method,

Acquiring values of operating parameters indicative of a pump condition of the pump by sensing means included as part of the variable frequency drive means and operably connected to the DC link;

Transmitting the value of the operating parameters from the variable frequency drive means to the control device;

Determining, by the control device, whether a predetermined condition is satisfied based on the obtained values of the operating parameters; And

Sending a command from the control device to the variable frequency drive means based on the fulfillment of the predetermined condition, in order to control the operation of the motor in accordance with the pump condition.

According to a second aspect of the invention, there is provided a pump configured to operate according to the method described above.

According to a third aspect of the invention, it is loadable into a memory 13 of a digital computer device, and when the computer program product runs on the digital computer device, it comprises a software code portion for performing the method according to the first aspect. A computer program product is provided.

According to a fourth aspect of the invention, there is provided a pump system comprising a pump according to the second aspect of the invention.

According to a further aspect of the invention, a control device for a pump according to the second aspect of the invention is provided.

The present invention therefore comprises the steps of: acquiring an operating parameter value of a pump substantially continuously from a variable frequency drive means, wherein said operating parameter is indicative of pump condition and simultaneously and accurately measured in an easy and inexpensive manner; And controlling the variable frequency drive means based on the obtained value of the operating parameter, wherein the operation of the motor is based on the idea of controlling the variable frequency drive means, which is adjusted according to pump conditions. Thereby, the pump is operated in an effective manner with respect to the output capacity at various flows, energy consumption and durability of the pump. In addition, pump life can be extended because wear of pump parts such as impellers and seals is reduced. Since all the information necessary for the control of the pump, the pump motor and the variable frequency drive means is obtained from the variable frequency means, no external sensor is necessary.

According to a preferred embodiment of the present invention, the operating parameter may be the DC link voltage of the variable frequency drive means, the DC link current of the variable frequency drive means, the speed of the motor, or the like. By this operating parameter, the power of the motor, the torque of the motor or other suitable quantities can be determined.

According to a preferred embodiment of the present invention, the case of the drying operation of the pump is determined based on the values of the obtained operating parameters, for example motor power at different motor speeds is compared with a predetermined reference value. If the power of the motor is lower than the predetermined reference level, the operation of the pump motor is stopped for a predetermined period of time. In addition, the motor is restarted if the same inspection is performed once again until the predetermined period of time has passed and the predetermined condition is met. Thus, as described above, the problem of snoring operation which further wears the pump, in particular in the impeller, causes the pump motor to overheat and further encourages unnecessary energy consumption, is solved, and the pump including the variable frequency drive means is used for energy consumption and A method of effectively operating in terms of durability is obtained. In addition, pump life, such as impellers, seals and suction covers, can be significantly reduced, resulting in extended pump life.

In an alternative embodiment of the invention, the power of the motor is maintained at a substantially constant level. If the value of the acquired operating parameter is compared with the predetermined reference level of the operating parameter, and if the value of the operating parameter is lower than the predetermined reference level, the speed of the motor required to obtain the predetermined power level is calculated, and the pump It works at its calculated speed. Preferably, the calculated speed is compared to the preset allowable maximum speed of the pump, so that if the calculated speed is higher than the preset maximum of the pump, the pump is operated at that preset speed. This solves the problem of maintaining high utilization of pump power over a wide flow range. As shown by line 32 in FIG. 3, the pump head / pressure can be reduced by 20% to 30% by the method according to the second aspect. Therefore, by increasing the speed of the motor, the pump will reach higher pump heads at lower flow than conventional pumps. Thus, a method of effectively operating a pump comprising variable frequency drive means in connection with the pump capability in various pump heads is obtained.

According to another embodiment of the invention, a detection is made as to whether the pump is clogged, so that if the pump is detected as clogged, the pump is operated in reverse at a predetermined speed for a predetermined period. The pump is then stopped and started in the normal direction. In addition, the step of operating the pump impeller in reverse, stopping the pump impeller, and then changing the direction of operation is repeated until it is detected that the blocked situation is finished. The problem of blockage or jam in the inlet and / or pumping house is therefore solved, which may be caused by particles in the fluid which settle in the inlet and impeller resulting in a silt having a relatively coarse or hard hardness. Due to the fact that the pump is operated again and again again and again, clogging can be effectively removed. Thereby, the reliability at the start can be improved. In addition, the present embodiment also provides a method of effectively operating a pump including variable frequency drive means in terms of energy consumption and durability, in particular because wear of the pump impeller is reduced. In addition, the energy consumption of the pump can also be reduced because the clogging situation can be effectively eliminated.

As will be realized by those skilled in the art, not only the preferred embodiment of the present invention but also the method according to the present invention preferably within the scope of the contents of the control device or processing means of the pump or pump system, As appropriate or realized.

Together with the objects and advantages of the present invention, features that characterize the present invention, both in terms of structure and method of operation, may be better understood by reading the following detailed description in conjunction with the accompanying drawings. It is to be understood that the drawings are for illustration and description only and are not intended to limit the invention. These and other objects, as well as the proposed advantages obtained by the present invention, will be fully understood when the following detailed description is read in conjunction with the accompanying drawings.

The foregoing and other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments, in conjunction with the accompanying drawings.

1 is a schematic diagram of an embodiment of a pump according to the invention.

2 is a schematic diagram of an embodiment of a pump system according to the invention.

3 is a diagram showing a pump curve for a conventional pump and a pump operating according to the present invention.

4 shows the principle of the method of an embodiment according to the invention.

5 shows the principle of a method of another embodiment according to the invention.

5 shows the principle of a method of another embodiment according to the invention.

7 is a schematic view showing a further embodiment of a pump according to the invention and a control device for such a pump.

8 is a schematic diagram showing another embodiment of a pump according to the invention and a control device for such a pump.

9 is a schematic diagram showing another embodiment of a pump and a pump system according to the present invention.

In the following, a preferred embodiment of the method of operating the pump and the pump system will be described.

First, a first embodiment of a pump according to the present invention will be described with reference to FIG. 1. For purposes of explanation, the embodiments of the invention described below are utilized in current submersible pumps comprising variable frequency drive means. However, as those skilled in the art will readily understand, the present invention can also be utilized with other types of pumps, such as sewage pumps, drain pumps, and dewatering pumps.

The submersible pump 1 of FIG. 1 is connected to a power supply (not shown) that transmits, for example, a single phase voltage or a three phase voltage via a variable speed unit 2, preferably via a connection cable 3. Variable frequency drive means (VFD unit). Unlike conventional pumps comprising a VFD unit, which are designed to receive power only in the range of about 200 V to about 250 V, the pump 1 according to the invention receives power in the range of about 90 V to about 250 V. Can be. Accordingly, the pump 1 of the present invention can be used in both countries / regions using a standard power source of about 110V and in countries / regions using a standard power source of about 230V. In contrast, conventional pumps are designed to be supplied with electricity having a frequency of 50 Hz or 60 Hz and are a well-known standard in several countries and / or in several regions within a country. However, the pump of the present invention is designed to be used in many different countries, ie the input frequency may be in the range of at least 50-60 Hz, but in practice the pump of the present invention can cope well with all useful frequencies. Thus, a given pump can be used in connection with many different power mains, that is, a given pump is a globally available pump that is ready to be put into operation.

The VFD unit 2 comprises an electromagnetic interference filter 4 (EMI filter) arranged in the connection cable 3 to filter the electromagnetic interference at the input. The connection cable 3 is connected to the feeder cable of the pump 1. The EMI filter 4 is connected to the rectifier 5, which is connected to the transducer or inverter 7 via a DC link 10 comprising a capacitor 6. The inverter 7 converts the DC current into a three-phase current, which is supplied to the pump motor 9 via a connection 8. The functions, components, and parts of the VFD unit 2 are well known to those skilled in the art and will not be described in further detail here.

The VFD unit 2 is thermally conductively placed with a pumped fluid while being mounted shielded from the motor 9 manually so that the temperature of the VFD 2 is kept at a low level during operation to eliminate the cause of the error. It is important to mount them in a thermally conductive arrangement.

The control device 11 is operably connected to the pump 1 and is configured to transmit to the VFD unit 2 via a communication bus (not shown), and with a high or low amount of fluid, for example water In order to pump, the pump 1 is controlled and driven to increase or decrease the speed of the motor 9, for example. In addition, the VFD unit 2 comprises a sensing means 16, which is operatively connected to the DC link 10, and which has the operating parameters of the pump 1 indicative of the pump condition. Configured to obtain a value.

The VFD unit 2 is arranged to transmit the value of the operating parameters to the control device 11, which operating parameters, according to a preferred embodiment of the invention, comprise a DC link voltage, a DC link current, a speed of the motor. And so on. By this operating parameter, the power of the pump 1 or the motor 9, the torque of the motor 9 or other suitable quantities can be determined. The control device 11 determines whether a predetermined condition is satisfied on the basis of the values of the operating parameters, and sends a command to the VFD unit 2 based on the fulfillment of the predetermined condition, so that the motor according to the pump condition The operation of (9) is controlled.

The control device 11 is also controlled by a processing means 12 comprising a storage means 13. The storage means 13 may comprise a nonvolatile memory such as random access memory (RAM) and / or read only memory (ROM). In this embodiment, the storage means 13 comprises a computer program 14 comprising instructions which cause a microprocessor, such as a computer or processing means 12, to bring up the method steps according to the invention. As will be appreciated by those skilled in the art, the storage means may comprise various types of physical devices for temporarily and / or permanently storing data, which may be solid state devices, Magnetic devices, optical devices, and combination devices. For example, the storage means can be implemented using one or more physical devices, such as DRAM, PROMS, EPROMS, EEPROMS, flash memory, and the like.

2, an alternative embodiment of the present invention will be described. In the present embodiment, the control device 11 comprises an operator unit 22 comprising input means in the form of a keyboard 24 for allowing an operator to input a control command, for example, information about the operation of the pump, For example, it is arranged to be connected via an interface unit (not shown) or display means or screen 26 for providing time history of operating parameters or status information of the pump. In one embodiment, the operator unit 22 is a personal computer. The communication link between the pump 1 and the operator unit 22 may be a wireless link or a wired link. In addition, the operator unit 22 may in turn be connected to a communication network such as the Internet. The operator unit 22 allows the operator to monitor not only the operation of the pump but also various operating parameters related to the operation of the pump via the display. According to another embodiment, the display is a touch sensitive screen, in which case a series of soft-keys can be arranged on the screen to provide different commands on the various provided interfaces on the display 26. In addition, the operator unit may include storage means (not shown), which may also include non-volatile memory such as random access memory (RAM) and / or read only memory. As will be appreciated by those skilled in the art, the storage means may comprise various types of physical devices for temporarily and / or permanently storing data, which may be solid state devices, magnetic devices, optical devices, etc. A device and a combination device are mentioned. For example, the storage means can be implemented using one or more physical devices, such as DRAM, PROMS, EPROMS, EEPROMS, flash memory, and the like.

In addition to service recording, the running data of the pump 1, such as running time, number of starts, energy consumption, and alarm data, are obtained and the logging file of the storage means 13 can be stored in a logging file. The logging file may be provided for the operator by the operator unit 22. In addition, the logging file can be downloaded to the operator unit 22 for storage, for example.

Of course, there are many possible designs for the control device 1, for example the control device may be implemented by a processor comprising programmable instructions for executing the method according to the invention. According to another embodiment, the control device may be implemented in the form of a microchip or in the form of a similar data carrier comprising software configured to carry out the functions described above and below. 7 to 9 also show alternative embodiments of the present invention. Similar parts and / or devices in FIGS. 1, 2 and 7-9 are designated by the same reference numerals. In FIG. 7, a control device 11, which can be protected by a sealed seal housing, is arranged on the outer surface of the pump housing. The control device 11 can be attached or fixed to the housing in various ways. For example, the control device 11 can be fixed using a screw. In FIG. 8, the control device 11 is in the form of a plug-in unit inserted into the control device accommodating portion 15. In FIG. 9, the control device 11 is arranged in the control panel 22.

Referring to FIG. 4, a general principle is described for a method of operating a pump according to the first aspect of the invention. According to this first aspect according to the present invention, as described above, the storage operation problem or the drying operation operation problem, which further wears the pump parts such as the impeller and seals, causes the pump motor to overheat and further causes unnecessary energy consumption. dry running operation problems). In addition, the pump motor is designed to perform optimally when the pump motor is pumped and operated in the fluid, causing the pump motor to be damaged due to extended drying operation. According to a first aspect of the invention, therefore, a pump comprising a VDF unit 2, as described with reference to any of FIGS. 1-2 and 7-9 with respect to energy consumption, pump life and durability. Operate (1) in an effective way.

First, in step 40, the operation of the pump is initialized, i.e. the pump is started. Then, in steps 42 and 44, it is determined whether the predetermined condition has been met. For example, in step 42, the pump operates at a first speed level for a predetermined period of time and also at a second speed level for a predetermined period of time. Preferably, the first speed level and the second speed level are low speed levels. For each speed level, the power of the motor 9 is determined, and then in step 44, the speed of the motor 9 and the speed of the motor 9 are determined using the two speed levels and the resulting power from each of these two speed levels. Check that the relationship between powers is almost a cube (if the power of the motor is proportional to the cube of the speed of the motor). If the relationship is a cubic function, the pump can operate in normal operation, but if the relationship is not a cubic function, the pump 1 is marked as pumping air and the fluid level is low so that the pump can be operated at the required speed level. It is judged not to be possible. This determination is carried out in the control device 11, for example the processing means 12. It must be pointed out that the relationship between the velocity level and the resulting power must be cubic, and other explanations may be appropriate for the mixing of other fluids, ie liquids and gases.

In step 44, if it is determined that the liquid level is insufficient, the algorithm proceeds to step 46, whereby the control device 11 sends a command to the VFD unit 2 for a predetermined period of time, for example, several minutes. During which the pump is stopped / paused for approximately two minutes.

On the other hand, in step 44, if it is determined that the liquid level is sufficient, the algorithm proceeds to step 48 where the speed of the pump 1 is increased to the desired speed. The pump 1 is now operated in the normal way.

In order to avoid a snorkeling operation, a substantially continuous check is made that the pump 1 does not pump air during operation. Therefore, in step 50, it is checked whether the pump 1 sucks air partially or fully or pumps the liquid by determining whether the liquid level is still sufficient, ie the second predetermined condition is met. This is done substantially continuously. In order to perform this inspection, the appropriate operating parameter value is acquired by the sensing means 16 of the VFD unit 2, and the value of this operating parameter is transmitted to the control device 11. For example, a DC link voltage, a DC link current, or the like can be used directly, or can be used, for example, to determine the torque of the motor 9 or preferably the power of the motor 9. The sudden drop in the power of the motor 9 during operation is an indication that the pump 1 is pumping air instead of liquid.

For example, the second condition is a comparison of the power of the motor 9 with, for example, a predetermined reference level, which can be stored in the storage means, if the power of the motor is lower than the predetermined reference level, the liquid level I think this is too slow. Preferably, the predetermined reference level may be about 70% of the maximum power of the motor relative to the current speed of the motor 9. Alternatively, a step comparable to step 42 may be performed on a regular basis between steps 48 and 50 to determine whether liquid is at the inlet of pump 1.

If it is determined that the liquid level at the inlet of the pump is sufficient, that is, the power of the motor 9 is determined to be higher than the predetermined reference level, the algorithm returns to step 48. On the other hand, if it is determined that the fluid level at the inlet of the pump is too slow, that is, if the power of the motor 9 is determined to be lower than the predetermined reference level, then the algorithm proceeds to step 52 where the operation of the pump is Is stopped. The algorithm then proceeds to step 46 where the operation of the pump remains stationary for a predetermined period of time. After this pause period elapses, the algorithm proceeds to step 42.

5, a second aspect of the method for operating a pump according to the second aspect of the present invention is described. According to this second aspect of the method according to the invention, the problem of maintaining the power of the pump at a substantially constant level over a wide range of flows is solved. As shown by line 32 in FIG. 3, the pump head / pressure can be increased by 20% to 30% by the method according to the second aspect. The power of the pump is maintained at a substantially constant level in the varying pump head by adjusting the speed of the motor. Due to the fact that the pump operates more effectively at slower flows, smaller pumps can be used to pump a given amount of liquid, and the wear of the pump can also be reduced. The pump of the present invention is a universal usable pump designed to be used in many different applications with varying requirements. By adjusting the speed of the motor a high pump capacity can be achieved for a given pump for the variable pump head. Therefore, according to the second aspect of the present invention, the pump including the VFD unit 2 is effectively operated as described with reference to any of FIGS. 1-2 and 7-9 in terms of energy consumption and durability. .

First, in step 60, the operation of the pump 1 is initialized, that is, the pump is started. Then in step 62, the pump is operated at the required speed level. The operating parameters of the pump are monitored substantially continuously and the values corresponding to these operating parameters are obtained by the sensing means 16 of the VFD unit 2, which are transmitted to the control device 11. For example, a DC link voltage, a DC link current, or the like can be used directly, or can be used, for example, to determine the torque of the motor 9 or preferably the power of the motor 9. In the control device 11, the power of the motor 9 can be stored in the storage means 13, for example in a predetermined reference level, for example in the processing means 12, in step 64. Is compared to the rated power of In step 64, if it is determined that the power level of the motor is higher than the predetermined reference level, the algorithm returns to step 62, and the operation of the pump is maintained at the required speed level. On the other hand, if it is determined that the power level of the motor is lower than the predetermined reference level, the algorithm proceeds to step 66 where the speed required to reach the predetermined power level of the motor is calculated by the processing means 12.

Then, in step 68, the calculated speed is compared with a preset maximum speed. If the calculated speed is found to be higher than the preset maximum speed, the algorithm proceeds to step 70 where the control device 11 commands the VFD unit 2 to operate the motor 9 at the preset maximum speed. , And the algorithm returns to step 64.

If the calculated speed is found to be lower than the preset maximum speed, the algorithm proceeds to step 72 and the control device 11 commands the VFD unit 2 to operate the motor 9 at the calculated speed. To transmit. The algorithm then proceeds to step 64 where the process continues. By maintaining the power of the motor at a substantially constant level, the head / pressure can be increased at low flow as indicated by line 32 in FIG.

Referring to FIG. 6, a general principle is described for a method of operating a pump according to a third aspect of the invention. According to this third aspect of the method according to the invention, the inlet and / or impeller of the pump 1 can be caused by particles in the fluid which settle in the inlet and the impeller resulting in a silt having a relatively coarse or hard hardness. The problem of blockage or congestion is solved. Therefore, in order to initialize the rotation of the pump impeller, a large starting torque of the pump motor is required. This consumes a large amount of energy and further wears out the pump impeller and motor. Even if the pump has been off-state for a long time, even the maximum starting torque may not be sufficient, in which case the pump must be cleaned manually, resulting in less reliable start-up of the pump operating in this environment. According to a third aspect of the present invention, therefore, the invention includes a VFD unit 2 as described with reference to any of FIGS. 1-2 and 7-9 with regard to energy consumption, durability and reliability at start-up. The pump works effectively.

First, in step 80, the operation of the pump 1 is initialized, that is, the pump 1 is started. Then, in step 82, the pump is operated at the required speed level. Then, in step 84, a check is made to see if the pump is clogged or congested. This may be an example performed in the following two ways. The first method measures the operating parameters of the pump and compares it with a predetermined reference level, for example, to determine the power of the motor 9 and to convert the power of this motor 9 into the power of this motor 9. To a predetermined reference level, for example rated power of the motor 9. If the measured power of the motor is above this predetermined reference level, it is a condition that is blocked or mixed. The second way is to monitor the alarm function of the variable frequency drive means 2 and use it as an indication of a condition that is blocked or mixed with an alarm indicating a DC link overcurrent.

In step 84, if the pump 1 is not clogged, the algorithm returns to step 82 so that the operation of the pump 1 is maintained. On the other hand, if it is determined that the pump 1 is blocked, the algorithm proceeds to step 86 where the control unit 11 commands the VFD unit 2 to reverse drive the impeller at the first speed for a predetermined period. To transmit. After the predetermined period, the pump 1 is stopped and then operated again in the forward rotational direction. Preferably, this cycle lasts about 1-10 seconds. Then, in step 88, it is checked whether the blocked state has stopped, as performed in step 84 above. If the blocked state has not stopped, the process returns to step 86. This cycle is repeated until the blocked situation is removed. If the blocked state has ceased, the algorithm returns to step 82.

In order to prevent clogging during normal operation of the pump 1, the following procedure can be carried out at regular intervals: the pump 1 is operated in reverse at a predetermined speed for a period having a predetermined length and the period After that, the pump 1 is stopped and then the pump 1 is operated in its normal direction of rotation. By this, the operating reliability of the pump can be further improved.

Referring to FIG. 3, the lines indicated by reference numerals 30 and 32 show the liquid flow and heat ratios for a given pump 1 that is supplied with a three phase voltage having a frequency of 60 Hz from the VFD unit 2. Yes. 60 Hz is the standard frequency of the power trunk in some countries, but with the VFD unit 2 this level can be raised considerably, for example up to 150 Hz, whereby the lines 30, 32 are shown in FIG. Some pumps may be used for highly varying applications and situations since they will be offset somewhat upwards in the chart.

Possible Modifications of the Invention

While specific embodiments have been shown and described for purposes of explanation and illustration, those skilled in the art will recognize that these specific embodiments shown and described may be substituted with a wide variety of alternatives and / or equivalent implementations without departing from the scope of the invention. I will understand. Those skilled in the art will readily appreciate that the present invention can be implemented in a wide variety of embodiments, including hardware implementations and software implementations, or a combination thereof. In one example, many of the functions described above may be acquired and performed by appropriate software contained in a microchip or similar data carrier. This application covers any configuration or modification of the preferred embodiments mentioned herein. In conclusion, the invention is defined by the claims appended hereto and their equivalents.

Claims (31)

In the method of operating the pump (1), The pump 1 comprises a motor 9 and variable frequency drive means 2, The variable frequency drive means 2 is connected to the motor 9 and to a feeder cable of the pump 1 to control the operation of the motor 9, rectifier 5, inverter (7) and a DC link (10) extending between the rectifier (5) and the inverter (7), In addition, the pump 1 is operably connected to the control device 11, The method of operating the pump 1, Operating parameter indicative of the pump condition of the pump 1 by means of sensing means 16 included as part of the variable frequency drive means 2 and operably connected to the DC link 10. Obtaining a value of Transmitting the values of the operating parameters from the variable frequency drive means (2) to the control device (11); Determining (44, 64, 84) by the control device (11) whether a predetermined condition is satisfied based on the obtained values of the operating parameters; And Transmitting a command from the control device 11 to the variable frequency drive means 2 based on the fulfillment of the predetermined condition, in order to control the operation of the motor 9 according to the pump condition. Method of operating a pump comprising a. The method of claim 1, Acquiring the values of the operating parameters of the pump 1, Obtaining a value of an operating parameter of at least one of an operating parameter consisting of a DC link voltage level, a DC link current level, a torque of the motor 9, or a power of the motor 9. Way. The method according to claim 1 or 2, Detecting (44, 64, 84) any one pump condition using the one or more operating parameters. The method of claim 3, The pump condition relates to the presence or absence of liquid at the inlet of the pump (1). The method of claim 4, wherein Determining whether the predetermined condition is satisfied, Operating (42) the pump (1) at a first speed level for a predetermined period of time; Operating (42) the pump (1) at a second speed level for a predetermined period of time; And Based on the values of the operating parameters obtained by the sensing means 16 for each of the first speed level and the second speed level, the power of the motor 9 is proportional to the cube of the motor 9 speed. Determining (44) Method of operating a pump comprising a. The method according to claim 4 or 5, The command transmitted from the control device 11 to the variable frequency drive means 2 is If it is determined that the predetermined condition is satisfied, the motor 1 is operated 48 at the required speed level, or If it is determined that the predetermined condition is not satisfied, causing the operation of the pump to stop (46) for a predetermined period of time. The method of claim 6, If the pump 1 is operated at the required speed level, By means of the sensing means 16 obtains values of operating parameters of the pump 1, Transmitting the values of the operating parameters from the variable frequency drive means 2 to the control device 11, Judge, by the control device 11, whether a second predetermined condition is satisfied based on the obtained values of the operating parameters, In order to control the operation of the motor 9, the pump (by sending a command from the control device 11 to the variable frequency drive means 2 based on the fulfillment of the second predetermined condition). Checking the presence of liquid at the inlet of 1) Method of operating a pump further comprising. The method of claim 7, wherein Determining whether the second predetermined condition is satisfied, Comparing (50) a value of said acquired operating parameters with a predetermined reference level. The method according to claim 7 or 8, The command transmitted from the control device 11 to the variable frequency drive means 2 is If it is determined that the second predetermined condition is satisfied, then operating the motor 1 at the required speed level (48), and If it is determined that the second predetermined condition is not satisfied, causing the operation of the pump (46) to stop (46) for a predetermined period of time. The method of claim 2, Maintaining the value of the at least one operating parameter at a substantially constant level. The method of claim 10, Determining whether the predetermined condition is satisfied, Operating (62) the pump (1) at the required speed level; And On the basis of the power values of the motor 9 obtained by the sensing means 16 for the required speed level, the power of the motor 9 is determined in advance with respect to the power of the motor 9. Determining if lower than 64 Comprising a pump. The method according to claim 10 or 11, wherein The command transmitted from the control device 11 to the variable frequency drive means 2 is If it is determined that the predetermined condition is not satisfied, the motor 1 is operated at the required speed level 62, or if it is determined that the predetermined condition is satisfied, the power of the motor 9 Calculate the speed of the motor 9 required to reach a predetermined reference level for To operate the pump at the calculated speed. The method of claim 12, If the pump 1 is operated at the required speed level, Comparing (68) the calculated speed of the pump (1) with a preset maximum speed of the pump (1); And Operate the pump 1 at the calculated speed 70 if the calculated speed is lower than the preset speed, or if the calculated speed is higher than the preset speed, operate the pump 1 with the preset speed. Operating at Set Speed (72) Method of operating a pump further comprising. The method of claim 3, The pump condition relates to clogging of the pump (1). The method of claim 14, Determining whether the predetermined condition is satisfied, Operating (82) the pump (1) at the required speed level; And On the basis of the power values of the motor 9 obtained by the sensing means 16 for the required speed level, the power of the motor 9 is determined in advance with respect to the power of the motor 9. Determine if higher (84) Comprising a pump. The method according to claim 14 or 15, The command transmitted from the control device 11 to the variable frequency drive means 2 is If it is determined that the predetermined condition is not satisfied, the motor 1 is operated at the required speed level 82 or the motor 1 is operated in reverse at a predetermined speed for a predetermined period of time. 86, and If it is determined that the predetermined condition is satisfied, after the predetermined period of operation in reverse, causing the pump (1) to operate in the normal direction of operation at the required speed level. The method of claim 16, Repeating (88) determining whether the power of the motor (9) is higher than a predetermined reference level for the power of the motor (9); And Repeating the steps according to claim 16 Method of operating a pump further comprising. The method of claim 14, Operating the motor (1) in reverse at a predetermined speed for a predetermined period of time; And After said predetermined period of operation in reverse, operating said pump 1 in the normal operating direction at the required speed level. Is performed at regular intervals during operation of the pump (1). In the computer program product 14, 19. Loadable into a memory 13 of a digital computer device, comprising a software code section for performing the method of any one of claims 1 to 18 when the computer program product 14 operates on the digital computer device. Computer program products. In a pump comprising a motor 9 and a variable frequency drive means 2, The variable frequency drive means 2 is connected to the motor 9 and to the feeder cable of the pump 1 to control the operation of the motor 9, the rectifier 5, the inverter 7, and A DC link (10) extending between the rectifier (5) and the inverter (7), The pump 1 is also operatively connected to the control device 1, The sensing means 16 is included as part of the variable frequency drive means 2 and is operatively connected to the DC link 10 so as to represent values of operating parameters indicative of the pump condition of the pump 1. Is configured to acquire The variable frequency drive means 2 is configured to transmit the values of the operating parameters to the control device 11, The control device 11 also determines whether a predetermined condition is satisfied based on the values of the acquired operating parameters, and controls the operation of the motor 9 according to the pump condition. Based on the satisfaction, the pump, which is configured to send a command to the variable frequency drive means (2). The method of claim 20, The control device 11 is configured to obtain a value of one or more operating parameters of the operating parameters consisting of a DC link voltage level, a DC link current level, a torque of the motor 9, or a power of the motor 9. Pump. The method of claim 21, The control device 11, Operating the pump 1 at a first speed level for a predetermined period of time, Operating the pump 1 at a second speed level for a predetermined period of time, Based on the value of the one or more operating parameters obtained by the sensing means 16 for each of the first speed level and the second speed level, the power of the motor 9 is equal to the speed of the motor 9 speed. A pump, configured to determine whether it is proportional to the cube. The method of claim 22, The control device 11, If it is determined that the predetermined condition is satisfied, the motor 1 is operated at the required speed level, or If it is determined that the predetermined condition is not satisfied, the pump is configured to stop the operation of the pump (1) for a predetermined period of time. The method of claim 21, The control device 11 is configured to maintain the value of the one or more operating parameters at a substantially constant level. The method of claim 24, The control device 11, Operating the pump 1 at the required speed level, On the basis of the power values of the motor 9 obtained by the sensing means 16 for the required speed level, the power of the motor 9 is determined in advance with respect to the power of the motor 9. A pump, configured to determine if lower. The method of claim 24 or 25, The control device 11, If it is determined that the predetermined condition is not satisfied, the motor 1 is operated at the required speed level, or if it is determined that the predetermined condition is satisfied, a predetermined value for the power of the motor 9 is determined. Calculate 66 the speed of the motor 9 required to reach the reference level, and A pump, configured to operate the motor (1) at the calculated speed. The method of claim 26, The control device 11, Comparing (68) the calculated speed of the pump (1) with a preset maximum speed of the pump (1), The pump 1 is operated 70 at the calculated speed if the calculated speed is lower than the preset speed, or the pump 1 is operated if the calculated speed is higher than the preset speed. A pump configured to operate (72) at a set speed. The method of claim 21, The control device 11, Operating (82) the pump (1) at the required speed level; On the basis of the power values of the motor 9 obtained by the sensing means 16 for the required speed level, the power of the motor 9 is determined in advance with respect to the power of the motor 9. A pump configured to determine (84) whether it is higher. The method of claim 28, The control device 11, If it is determined that the predetermined condition is not satisfied, the motor 1 is operated at a required speed level, or the motor 1 is operated 86 at a predetermined speed for a predetermined period of time, and And If it is determined that the predetermined condition is satisfied, the pump is configured to operate in the normal direction of operation at the required speed level after the predetermined period of operation in reverse. The method of claim 21, The control device 11 is operated at regular intervals during the operation of the pump 1, Operating the motor 1 in reverse at a predetermined speed for a predetermined period of time, and After the predetermined period of operation in reverse, the pump (1) is configured to operate in the normal operating direction at the required speed level. 31. A pump 1 according to any one of claims 20 to 30, A pump station comprising an input means (24) and a display means (26) and configured to provide information relating to the operation of the pump (1).

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