WO2015029147A1

WO2015029147A1 - Pump system

Info

Publication number: WO2015029147A1
Application number: PCT/JP2013/072936
Authority: WO
Inventors: 敏夫富田; 大久保　智文; 佐野　正浩
Original assignee: 株式会社日立産機システム
Priority date: 2013-08-28
Filing date: 2013-08-28
Publication date: 2015-03-05
Also published as: JPWO2015029147A1; CN105452670B; CN105452670A; JP6134800B2

Abstract

　A pump system having a pump unit that has an impeller provided inside a pump casing, a synchronous motor for rotatably driving the impeller, and an inverter for controlling the synchronous motor, wherein the inverter has a signal input unit for inputting signals from a pressure detection means for detecting water pressure provided to a discharge side of the pump unit, a calculation processor for deciding the rotational speed of the synchronous motor, a storage unit for storing control parameters needed for the calculations performed by the calculation processor, and a power converter for supplying a drive current to the synchronous motor; and the calculation processor stops the synchronous motor and performs a restarting process when a pressure change of a prescribed value or greater is detected according to a signal from the pressure detection means, and performs a second restart using a rate of increase different from the rate of increase in rotational speed of the synchronous motor during the first restart in a case when the synchronous motor does not start up normally in the first restart.

Description

Pump system

The present invention relates to a pump system using an inverter for controlling a synchronous motor.

Conventionally, induction motors have been mainly used as a drive source for pumps, but synchronous motors using permanent magnets are now being used from the viewpoint of energy saving and high efficiency. Among the synchronous motors, the motor that does not include the magnetic pole position sensor has the advantage that the magnetic pole position sensor does not have a failure and can be reduced in price.

On the other hand, in the case of a synchronous motor without a magnetic pole position sensor, a phenomenon called out-of-step occurs in which the rotational speed recognized by the inverter that controls the motor does not match the actual rotational speed of the motor, and the load does not rotate. There is a risk of not working. In the case of a pump, the desired water supply cannot be performed, and there is a possibility that the drinking water may be stopped or the facility may be stopped.

For example, according to the following Patent Document 1, an abnormality in the rotation state of the electric motor can be detected by an estimation calculation of the shaft error of the electric motor.

JP 2012-60781 A

However, even in a step-out state, a current corresponding to the induced voltage flows through the motor, and the current value is almost equal to the current value in the normal rotation state. Therefore, in the method of estimating the axis error from the voltage command value and the current detection value described in Patent Document 1, it is difficult to detect the step-out because the change in the current value is minute.

The present invention has been made in view of the above circumstances, and in a pump system, it is possible to detect a step-out easily and restart the electric motor as necessary to stably drive the load and continue water supply. Objective.

In order to solve the above problems, in the present invention, as an example, a pump unit having an impeller provided in a pump casing, a synchronous motor that rotationally drives the impeller, an inverter that controls the synchronous motor, The inverter has a signal input unit for inputting a signal from a pressure detection means for detecting water pressure provided on the discharge side of the pump unit, and an operation for determining the rotational speed of the synchronous motor A processing unit, a storage unit that stores control parameters necessary for calculations performed by the calculation processing unit, and a power conversion unit that supplies a drive current to the synchronous motor, wherein the calculation processing unit includes the pressure When a change in pressure equal to or greater than a predetermined value is detected by a signal from the detection means, the synchronous motor is stopped and restarted, and the synchronous motor is restarted at the first restart. If the machine does not start normally, the second restart is performed at an increase rate different from the increase rate of the rotational speed of the synchronous motor at the first restart.

According to the present invention, even when a step-out occurs and the load does not rotate and does not work, the motor can be restarted quickly, the load can be driven, and the work can be continued. Therefore, stable water supply can be performed.

Overall configuration of a pump system in an embodiment of the present invention Configuration of the inverter in the embodiment of the present invention Data contents of the storage unit in the embodiment of the present invention Control flow in constant speed operation of pump in the first embodiment of the present invention Control flow of abnormality processing in the first to third embodiments of the present invention Control flow in automatic operation of constant water supply pressure of automatic water supply apparatus in first embodiment of the present invention Control flow in constant speed operation of the pump in the second embodiment of the present invention Control flow in automatic operation of constant water supply pressure of automatic water supply apparatus in the second embodiment of the present invention Control flow of automatic operation of constant water supply pressure of automatic water supply apparatus in third embodiment of the present invention Control flow (example 1) of pump characteristic calculation processing in the third embodiment of the present invention Control flow of pump characteristic calculation processing in the third embodiment of the present invention (example 2) Explanatory drawing of the pressure change by the step-out in the 1st Embodiment of this invention Explanatory drawing of the pressure change and load current value change by the step-out in the 2nd Embodiment of this invention Explanatory drawing of the pump characteristic in the 2nd Embodiment of this invention FIG. 1 is an explanatory diagram of pump characteristics in the third embodiment of the present invention. FIG. 2 is an explanatory diagram of pump characteristics according to the third embodiment of the present invention.

In the first embodiment of the present invention, an abnormality (step-out) is detected by a change in the secondary pressure of the pump in a synchronous motor that is driving a pump.

Check the secondary pressure of the pump, and if the amount of change exceeds a predetermined value, stop the pump once, restart it, check the secondary pressure of the pump again, and set the secondary pressure to the predetermined value. If it has reached, it is judged that it was out of step.

First, FIG. 1 shows the overall configuration of the pump system of the present invention. In FIG. 1, a pump 10 provided with an impeller in a pump casing is driven by an electric motor 20. The electric motor 20 is a synchronous motor that does not include a magnetic pole position sensor. Further, an inverter 30 is connected to the electric motor 20, and the inverter 30 changes the frequency of the output current, thereby driving the electric motor 20 by changing the number of rotations. The pressure detection means 11 is provided in the secondary side piping of the pump 10, and the pump discharge side pressure is detected.

FIG. 2 shows the internal configuration of the inverter 30. An AC-DC converter 31 is connected to a power receiving unit that receives power supplied to the inverter 30, and the received AC power is converted into a DC voltage. This DC voltage is converted again by the DC-AC converter 32 into an AC power source having a frequency designated by the arithmetic processing unit 34. When changing the rotation speed of the load, a signal is input to the signal input unit 33. A frequency to be output by the arithmetic processing unit 34 is determined according to the input signal, and an instruction is issued to the DC-AC converter 32 to generate an AC power source of that frequency. Control parameters necessary for the calculation performed by the calculation processing unit 34 are stored in the storage unit 35 in advance, and the calculation processing unit 34 reads and writes the memory contents of the storage unit 35 as necessary.

FIG. 3 shows the contents stored in the storage unit 35 composed of a volatile memory and a nonvolatile memory. It should be noted that the storage unit may not be provided inside the inverter 30, and a storage device may be attached outside the inverter and used instead.

Record the rotation speed (command frequency to the motor) HzN when starting the abnormality determination at address 1000 of the volatile memory. At the address 1001, the pressure (discharge side pressure) HN on the secondary side of the pump when the abnormality determination is started is recorded. The control parameter at address 1002 is not used in the first embodiment. The remaining time TN1 of the timer for setting the cycle for performing the abnormality determination process is stored at address 1003, and the remaining time TN2 of the timer for checking the occurrence frequency of the abnormality is stored at address 1004. As a result of the abnormality determination, the number CN of restarts is stored at address 1005. The control parameters from addresses 1006 to 1009 are not used in the first embodiment of the present invention. At address 1010, the initial pump secondary pressure (discharge pressure) Hm is stored. The address 1011 stores the frequency increase rate D1 when the pump is restarted (first time), and the addresses 1012 store the frequency increase rate D2 when the pump is restarted (after the second time).

The pressure reference value HDG on the pump secondary side used for determination in the abnormality determination process is stored in advance at address 2001 of the nonvolatile memory. The control parameter at address 2002 is not used in the first embodiment of the present invention. A cycle TM1 for performing abnormality determination processing is stored in advance at address 2008. In the address 2009, a timer set time TM2 for confirming the occurrence frequency of the abnormality is stored in advance.

A parameter SLD for selecting whether or not to execute the abnormality determination function is stored in advance at address 2010. If the user sets SLD to 0, the abnormality determination process is not performed. If the user sets SLD to 1, the abnormality determination process is executed when the condition is satisfied. The control parameters from addresses 3100 to 3215 are not used in the first embodiment.

At address 7001, a parameter SLA for selecting whether or not to output a failure signal when the number of restart executions reaches the number of times ALE stored in advance at address 7002 is stored in advance. At address 8001, a parameter SLR for selecting whether or not to allow the motor to be restarted when an abnormality is determined in the abnormality determination process is stored in advance. The automatic restart permission upper limit number RSE is stored in advance at address 8002, and when the restart execution number CN exceeds the RSE, restart of the motor is not permitted and the motor is kept stopped.

In the present embodiment, it is preferable to set the SLA at address 7001 to 1, the ALE at address 7002 to 2, the SLR at address 8001 to 1, and the RSE at address 8002 to 1. In the case of a pressure drop due to the impeller stoppage due to accidental step-out, the pressure drop occurs only once. At this time, the pump can be restarted without issuing a failure signal, and water supply can be continued. When the discharge side pressure is reduced due to factors other than step-out, such as breakage of the discharge side piping, or when the pump is falling, the pressure drops multiple times. At this time, it is possible to protect the pump and related equipment by outputting a failure signal, notifying the abnormality, and stopping the pump without restarting it.

However, for example, in the case of step-out due to foreign matter, it may occur repeatedly even if step-out occurs. Even in such a case, as in the case of factors other than the above-described step-out, the pump and related equipment are stopped without restarting more than necessary in order to protect the pump and related equipment.

When automatic operation is performed so that the supply water pressure is constant by an automatic water supply device at address 9001, a target water supply pressure value HS is stored in advance and detected by the pressure detection means 11 provided on the secondary side pipe of the pump 10 The rotation speed is automatically controlled so that the value matches HS.

FIG. 4 shows a control flow of the first embodiment of the present invention when the pump is operated at a constant speed (a constant rotation speed and a constant frequency).

After the operation is started in step 101, the speed reaches the speed specified in step 102, and the discharge-side pressure value Hm at that time is stored in the volatile memory 1010. (103 step) The step-out determination function selection confirmation process is performed in 104 step. When the step-out determination function is selected, the following steps are performed. In step 105, the set value of the abnormality determination cycle timer TM1 stored in advance in the nonvolatile memory 2008 is stored in the remaining time TN1 of the timer 1 in the volatile memory 1003, and the countdown of TN1 is started. If the count of the timer TN1 has not ended in 109 steps, the process waits for the timer TN1 to end, and returns to 109 steps. If the count of the timer TN1 has ended, the current discharge side pressure is stored in the volatile memory in 134 steps. Store as HN at address 1001. In step 140, it is determined whether the difference between Hm and HN is less than the HDG stored in advance in the nonvolatile memory address 2001.

If the difference between Hm and HN is less than HDG, it is determined as normal in 160 steps, and the number of restarts CN of the volatile memory 1005 is set to 0 in 165 steps. The timer count is restarted in step 181 and the process returns to step 109.

If the difference between Hm and HN is greater than or equal to HDG, there is a possibility of step-out, so it is determined that there is an abnormality. After 170 steps of abnormal processing, restart processing is performed and then the pump is restarted in 180 steps. The timer is started, the timer count is restarted in step 181 and the process returns to step 109. Although Hm is unchanged in FIG. 4, it may be updated by copying the value of HN to the value of Hm at the time of step 181.

As shown in FIG. 12, when a step-out occurs while the pump is operating at a certain rotation speed, the pump's ability to pump water is lost, so the discharge pressure on the pump is greatly reduced. How much the pressure decreases depends on the suction conditions (primary side state) of the pump. Therefore, it is preferable to determine the determination reference value HDG for the discharge side pressure in consideration of the suction conditions.

In the present invention, when the discharge side pressure of the pump is greatly reduced, the pump is stopped and restarted. If the discharge-side pressure drops without returning to the normal state at the first restart, the second and subsequent restarts are performed. Here, the increasing rate of the command frequency indicating the rotation speed of the synchronous motor in the first restart is set smaller than the increasing rate of the command frequency in the second and subsequent restarts. This is because, when the abnormality that has occurred is an accidental step-out, it is easy to return to the normal state by gradually increasing the command frequency at the first restart. When the normal state is restored by the first restart, it can be determined that the cause of the large decrease in the discharge-side pressure was a step-out. Although not shown, it is possible to output or display the information to the outside, assuming that the cause of the pressure change is step-out.

On the other hand, if it does not return to the normal state after the first restart, there may be an abnormality caused by air accumulation, etc. In this case, the increase rate of the command frequency is increased and restarted after the second restart. Foreign matter may be removed by repeating the start-up.

In the example of FIG. 12, the increase rate of the command frequency at the first restart is made smaller than the increase rate of the command frequency at the second restart, but the frequency increase rate at the second restart is reduced. It is also possible to make it smaller than the frequency increase rate at the start. For example, even if accidental step-out occurs, the normal state can be quickly restored by restarting with a large frequency increase rate. In the second and subsequent times, it may be possible to set a moderate increase rate of the command frequency preliminarily for a case where the recovery to the normal state at the first restart fails due to the accidental step-out.

FIG. 5 shows details of 170-step abnormality processing. After determining the abnormality in step 300, the current number of restarts is updated in

step

301, 1 is added to the stored value of the volatile memory 1005, and the pump is stopped in step 302. In step 303, a parameter SLA for selecting whether or not to output a failure signal stored in advance in the non-volatile memory 7001 is confirmed. If SLA is set to 0, no failure signal is output in

step

306 and 306 is output. Proceed to step. If the SLA is set to 1, the abnormality detection count ALE that starts outputting the failure signal stored in advance in the nonvolatile memory 7002 in step 304, and the current stored in the volatile memory 1005 The restart execution times CN are compared, and if ALE is greater than or equal to CN, a failure signal is output in step 305. If ALE is less than CN, it is determined in step 306 that no failure signal is output, and the flow proceeds to step 307.

Confirm the restart permission in step 307. It is desirable to change the conditions for restart permission depending on the number and frequency of restarts, the characteristics of the equipment, and the intended use. The parameter SLR for selecting the automatic restart permission stored in advance in the non-volatile memory 8001 is confirmed. If the restart is permitted, the process proceeds to step 308. If not permitted, the process proceeds to step 309. Wait for input. In step 308, if the number of detected abnormalities is 1 or less, the increase rate of the command frequency at restart stored in advance in the non-volatile memory 1011 in step 310 is set to D1. When the number of times of abnormality detection is two or more, the increase rate of the command frequency at restart stored in advance in the nonvolatile memory 1012 at step 311 is set to D2.

Although not shown in FIG. 5, the upper limit number RSE of automatic restarts is compared with the current restart execution number CN stored in the volatile memory 1005, and when RSE exceeds CN, A reset instruction may be given manually.

When adding a frequency to the restart permission condition, the set value of the abnormality frequency confirmation timer TM2 stored in advance in the nonvolatile memory 2009 at the time of detecting the abnormality is set to the timer in the volatile memory 1004. 2 The remaining time is stored in TN2, and TN2 is counted down. If an abnormality is detected again before TN2 becomes 0, a condition that restart is not permitted may be added. For example, if TN2 is set to 1 hour, when an abnormality is detected twice within 1 hour, it can be estimated that the cause is not an accidental step-out, but an external factor.

FIG. 6 shows a control flow of the present invention when the automatic operation is performed so that the supply water pressure is constant by the automatic water supply device.

When a decrease in the discharge side pressure is detected in step 100, operation starts in step 101, and then the speed specified in step 102 is reached. In step 104, step-out determination function selection confirmation processing is performed. If the selection of the step-out determination function is confirmed, it is determined in step 130 whether the current discharge-side pressure is higher than the target pressure HS stored in advance in the nonvolatile memory 9001. If the current discharge-side pressure is higher than the target pressure HS, a deceleration instruction is issued in 131 steps. When an instruction for deceleration is given, the output frequency is changed in 132 steps. Conversely, if the current discharge-side pressure is lower than the target pressure HS, an acceleration instruction is given in step 133. When acceleration is instructed, the output frequency is changed in 135 steps.

Next, the setting value of the step-out determination cycle timer TM1 stored in advance in the non-volatile memory 2008 at step 105 is stored in the timer 1 remaining time TN1 of the volatile memory 1003, and the countdown of TN1 is performed. Start. After confirming the end of the countdown of TN1 in step 109, the current discharge side pressure HN is stored in step 134, and it is determined in step 142 whether the difference between HN and the target pressure HS is less than HDG.

When the difference between the discharge side pressures HN and HS is less than HDG, it is judged normal at 160 steps, and the restart execution count CN of the volatile memory 1005 is set to 0 at 165 steps. Then, the process returns to step 130.

If the difference between the discharge side pressure and HS is greater than or equal to HDG, it is determined that there is a possibility of a step-out, and the process at the time of abnormality in 170 steps is performed. And return to step 130.

Since the process at the time of abnormality in 170 steps is the same control flow (FIG. 5) as when the pump is operated at a constant speed (a constant rotation speed and a constant frequency), the description is omitted.

In the second embodiment of the present invention, in a synchronous motor that is driving a pump, a step-out is detected by a change in the pump secondary pressure and a change in the load current value.

When the pump secondary pressure drops, if the pump load current value does not exceed a certain value, it is judged that there is a possibility of step-out, and normal operation is resumed by restarting the motor. To do. The structure is the same as that of the first embodiment shown in FIGS.

FIG. 3 shows the contents of the volatile memory and the nonvolatile memory stored in the storage unit. The contents of the memory are the same as in the first embodiment, but in this embodiment, the load current value AN on the secondary side of the pump when starting the step-out determination is recorded at address 1002.

FIG. 7 shows a control flow of this embodiment when the pump is operated at a constant speed (a constant rotation speed and a constant frequency).

Start operation in step 101. After reaching the speed specified in step 102, the original discharge-side pressure Hm is stored in address 1010 of the volatile memory in step 103. In step 104, step-out determination function selection confirmation processing is performed. When the step-out determination function is selected, the timer starts counting in 105 steps. In step 109, it is confirmed that the timer count has ended. In step 106, the current discharge-side pressure is stored as HN in the volatile memory 1001. In step 107, the current load current value is stored as AN in the volatile memory 1002.

As shown in FIG. 13, even in a step-out state, a current corresponding to the induced voltage flows through the motor, and a current substantially equal to the value in the normal rotation state flows. When step-out occurs, the pump's ability to pump water is lost, so that the discharge side pressure of the pump greatly decreases, but the load current value does not change significantly.

Fig. 14 shows general pump characteristics. When operating at an arbitrary frequency HzN, the discharge-side pressure is Ha and the load current value is Aa at the discharge flow rate Qa. Here, when the discharge flow rate increases from Qa to Qb, the discharge side pressure decreases to Hb, and the load current value increases to Ab. It can be seen that the load current value increases as the discharge side pressure decreases.

Therefore, if HN-Hm is greater than or equal to HDG in step 143, it is determined normal in step 160 and the process returns to step 105.

If HN−Hm is less than HDG, it is determined whether the current load current value is greater than AN + ADG in 144 steps, and if it is greater than AN + ADG, it is determined normal in 161 steps, and the process returns to 105 steps.

If it is less than AN + ADG, it is determined that the step is out of step, the process at the time of abnormality of 170 steps is performed, the restart process is performed, the pump is restarted at 180 steps, and the process returns to 105 steps. In the state of FIG. 13, it is possible to return to a normal state before the pressure is greatly reduced by detecting that it is out of step and performing the restart earlier. Thereby, the influence on water supply by step-out can be minimized. The abnormality process in 170 steps is the same as that in the first embodiment and is shown in FIG.

FIG. 8 shows a control flow of the present invention in the case where automatic operation is performed so that the supply water pressure becomes constant by the automatic water supply apparatus.

When a decrease in discharge side pressure is detected in step 100, operation starts in step 101. After reaching the speed specified in step 103, step-out determination function selection confirmation processing is performed in step 104. After the step-out determination function selection confirmation process, the current load current value is stored as AN in the volatile memory 1002 at step 107. In step 130, it is determined whether the discharge side pressure is higher than the target pressure HS stored in advance in the nonvolatile memory 9001. When the discharge side pressure is higher than the target pressure HS, a deceleration instruction is issued in 131 steps. When an instruction for deceleration is given, the output frequency is changed in 132 steps. On the other hand, if the discharge side pressure is lower than the target pressure HS, the acceleration is instructed in step 133. When acceleration is instructed, the current discharge-side pressure is stored as HN in the volatile memory 1001 at 134 steps, and then the output frequency is changed at 135 steps.

If the specified speed is reached, go to step 143. Hereinafter, since the control flow is the same as that in the case of operating the pump at a constant speed (a constant rotation speed, a constant frequency) (FIG. 7) after Step 143, the description is omitted.

In the second embodiment, the step-out can be detected more accurately by combining the discharge side pressure and the load current value.

Next, a third embodiment of the present invention will be described. In the third embodiment, the pump characteristic data is stored in the storage unit, and the discharge side pressure or the load current value at the operation frequency (command frequency) during the pump operation matches the value calculated from the characteristic data. A step-out is detected by comparing whether or not to do so.

When the discharge side pressure calculated from the pump characteristic data and the detected discharge side pressure, or the difference between the load current value calculated from the pump characteristic data and the detected load current value exceeds the criterion value It is determined that there is an abnormality, and normal operation is started again by restarting the motor.

First, the structure is the same as that of the first embodiment shown in FIGS. FIG. 3 shows the contents of the volatile memory and the nonvolatile memory stored in the storage unit.

The calculated discharge side pressure HC obtained by the pump characteristic calculation process is stored at address 1006 of the volatile memory. Similarly, the calculated load current value AC obtained by the pump characteristic calculation process is stored at address 1007. The calculated flow rate QC obtained by the pump characteristic calculation process is stored at address 1008. At address 1009, it is determined whether or not the difference between the result obtained by the pump characteristic calculation process and the actual detection value is within the determination reference value, and the result is stored. If the calculated value and the detected value match, 0 is stored, and if the calculated value and the detected value do not match, 1 is stored.

The pump characteristic data is recorded at addresses 3100 to 3215 of the nonvolatile memory. Pump at measurement point 1 (recorded at 3100), flow rate (recorded at 3101), current (recorded at 3102), head at measurement point 2 (recorded at 3101) in operation at an arbitrary frequency of the pump (recorded at 3115) 3120), flow rate (recorded at 3104 address), current (recorded at 3105 address), and lift at measurement point 3, measurement point 4, flow rate, current, lift at measurement point 5 (recorded at address 3112) , The flow rate (recorded at address 3113) and the current (recorded at address 3114) are stored in advance in a nonvolatile memory. FIG. 15 shows the relationship between the pump characteristic data stored in addresses 3100 to 3215.

One set of pump characteristic data may be used, but since it is better that the current frequency and the frequency of the pump characteristic data recorded in advance are closer in the pump characteristic calculation process, measurement points 1 to 4 at other frequencies (recorded at 3215) It is better to store the head, flow rate, and current at 5. Needless to say, it is better to store three or more frequencies and corresponding data instead of two frequencies.

Other contents of the volatile memory and the non-volatile memory to be used are the same as those in the first and second embodiments, and the description thereof will be omitted.

FIG. 9 shows a control flow of the present invention in the case where automatic operation is performed so that the supply water pressure becomes constant by the automatic water supply apparatus.

When a decrease in discharge side pressure is detected in step 100, operation starts in step 101. After reaching the speed specified in step 103, step-out determination function selection confirmation processing is performed in step 104. Thereafter, in step 130, it is determined whether the discharge side pressure is higher than the target pressure HS stored in advance in the nonvolatile memory 9001. When the discharge side pressure is higher than the target pressure HS, a deceleration instruction is issued in 131 steps. When an instruction for deceleration is given, the output frequency is changed in 132 steps. On the other hand, if the discharge side pressure is lower than the target pressure HS, the acceleration is instructed in step 133. When acceleration is instructed, the output frequency is changed in 135 steps.

In step 151, the current discharge side pressure is stored as HN in the volatile memory 1001, and in step 152, the current load current value is stored as AN in the volatile memory 1002. After the current command frequency is stored as HzN in the volatile memory 1000 at step 153, pump characteristic calculation processing is performed at step 154.

In step 155, it is determined whether the current output (detected value) matches the calculation result (calculated value). If they match (when the value CS stored in the volatile memory 1009 is 0), it is determined to be normal in 160 steps, and the process returns to 103 steps. If the current output (detected value) and the calculation result (calculated value) do not match (when CS is 1), it is determined that the step is out, 170-step abnormality processing is performed, and restart processing is performed. Later, the pump is restarted in 180 steps and the process returns to 103 steps.

Since the processing at the time of abnormality in 170 steps is the same as before, the explanation is omitted.

FIG. 10 shows details (example 1) of the pump characteristic calculation process of 154 steps.

In 400 steps, HzN is read from the volatile memory address 1000, HN is read from the address 1001, and AN is read from the address 1002.

Although details will be described later, in step 401, the pump characteristic curve at the current command frequency HzN is calculated from HzN and the characteristic data recorded in advance at addresses 3100 to 3215 of the nonvolatile memory.

The current flow rate QC is calculated from the pump characteristic curve calculated in step 411 and the current discharge side pressure HN. From the flow rate QC calculated in step 412 and the current command frequency HzN, a calculated load current value AC at the flow rate QC is obtained. In step 413, it is confirmed whether the difference between the current load current value AN and the calculated load current value AC is smaller than the ADG stored in advance in the non-volatile memory 2002, and the difference between AN and AC is within ADG In step 431, the current output coincides with the calculation result, and 0 is stored in the comparison CS with the calculation result of the volatile memory 1009. If the difference between AN and AC exceeds ADG, the current output and the calculation result do not match at

step

432, and 1 is stored in CS. Proceed to step 155 after the process is completed.

FIG. 11 shows another example (Example 2) of the pump characteristic calculation process of 154 steps.
In FIG. 10 (example 1), the flow rate QC is calculated from the discharge side pressure in step 411, the load current value AC is calculated in step 412, the current load current value AN and the calculated load current value AC are calculated in step 413. Compare.
In contrast, in FIG. 11 (example 2), the flow rate QC is calculated from the load current value in step 421, the discharge side pressure HC is calculated in step 422, the current discharge side pressure HN in step 413, and the calculated discharge side. Compare the pressure HC.

The pump characteristic calculation process will be described in more detail. The current pump operation state is calculated from the flow rate, discharge side pressure, load current value, current discharge side pressure HN or load current value AN at each frequency recorded in advance in the storage unit.

First, check whether there is pump characteristic data with a frequency that matches the current command frequency HzN. If it does not exist, an approximate calculation of the pump performance is performed from the performance data at the frequency closest to the command frequency HzN (corresponding to step 400 in FIG. 10 or FIG. 11). In the pump performance, the flow rate is proportional to the frequency by a linear function, the discharge side pressure is proportional to the quadratic function, and the current value is proportional to the cubic function. From this, pump characteristic data during operation at the current command frequency HzN is calculated from the data of the pump characteristics having a frequency stored in advance close to the command frequency HzN according to a similarity rule.

First, the coefficients FC1, FC2, and FC3 used in the similarity law calculation from Equation 1, Equation 2, and Equation 3 are as follows: FC1 = (F1 ÷ FC) Equation 1
FC2 = (F1 ÷ FC) ² Formula 2
FC3 = (F1 ÷ FC) ³ Equation 3
I ask.

For example, if the frequency data closest to the current command frequency HzN is Hz1 recorded at address 3115, the performance data H11, H12, H13, H14, H15 (3100, 3103,... (Recorded at address 3112) is multiplied by FC1 to obtain HC1, HC2, HC3, HC4, and HC5. Similarly, the flow rate performance data Q11, Q12, Q13, Q14, Q15 (recorded at addresses 3101, 3104,..., 3113) are respectively multiplied by FC2 to obtain QC1, QC2, QC3, QC4, and QC5. Further, the performance data A11, A12, A13, A14, A15 (recorded at addresses 3102, 3105,..., 3114) related to current are respectively multiplied by FC3 to be AC1, AC2, AC3, AC4, and AC5.

The approximation is obtained, for example, from Newton's interpolation method or Lagrange's interpolation polynomial. When Newton's interpolation method is used, the characteristic curve of the discharge side pressure with respect to the discharge flow rate: QH curve (Hi (Qi))
C0 = HC1
C1 = (HC2-HC1) ÷ (QC2-QC1)
C2 '= (HC3-HC1) / (QC3-QC1)
C2 = (C2′−HC2) ÷ (QC3-QC2)
C3 ″ = (HC4−HC1) ÷ (QC4-QC1)
C3 ′ = (C3 ″ −HC2) ÷ (QC4-QC2)
C3 = (C3′−HC3) ÷ (QC4-QC3)
C4 ′ ″ = (HC5−HC1) ÷ (QC5-QC1)
C4 ″ = (C4 ′ ″ − HC2) ÷ (QC5-QC2)
C4 ′ = (C4 ″ −HC3) ÷ (QC5-QC3)
C4 = (C4′−HC4) ÷ (QC5-QC4)
Then,
Hi (Qi)
= C0
+ C1 x (Qi-QC1)
+ C2 × (Qi−QC1) × (Qi−QN2)
+ C3 × (Qi−QC1) × (Qi−QN2) × (Qi−QC3)
+ C4 × (Qi−QC1) × (Qi−QC2) × (Qi−QC3) × (Qi−QC4)
... Formula 4
Is required.

Similarly, the characteristic curve of the load current value with respect to the discharge flow rate: QA curve (Ai (Qi))
C5 = AC1
C6 = (AC2-AC1) / (QC2-QC1)
C7 '= (AC3-AC1) / (QC3-QC1)
C7 = (C7′−AC2) ÷ (QC3-QC2)
C8 ″ = (AC4−AC1) ÷ (QC4-QC1)
C8 ′ = (C8 ″ −AC2) ÷ (QC4-QC2)
C8 = (C8′−AC3) ÷ (QC4-QC3)
C9 ′ ″ = (AC5-AC1) ÷ (QC5-QC1)
C9 ″ = (C9 ′ ″ − AC2) ÷ (QC5-QC2)
C9 ′ = (C9 ″ −AC3) ÷ (QC5-QC3)
C9 = (C9′−AC4) ÷ (QC5-QC4)
Then,
Ai (Qi)
= C5
+ C6 x (Qi-QC1)
+ C7 × (Qi−QC1) × (Qi−QN2)
+ C8 × (Qi−QC1) × (Qi−QN2) × (Qi−QC3)
+ C9 × (Qi−QC1) × (Qi−QC2) × (Qi−QC3) × (Qi−QC4)
... Formula 5
(Equation 4 corresponds to step 401 in FIG. 10 and equation 5 corresponds to step 401 in FIG. 11). FIG. 16 shows the QH curve (Hi (Qi)) and the QA curve (Ai (Qi)).

Since the solution of the quartic equation is difficult, for example, using the substitution method, the flow rate QC when the load current value is AC at the command frequency HzN is obtained from Equation 5 (corresponding to step 421 in FIG. 11). From Equation 4, the discharge-side pressure HC when the flow rate is QC at the command frequency HzN can be obtained (corresponding to step 422 in FIG. 11).

Thus, since the QH curve and QA curve are obtained by approximation from the pump characteristic data closest to the command frequency HzN, it is desirable that there are about five pump characteristic data to be measured and stored in advance for each frequency.

As described above, the frequency of the pump characteristic data that is measured and stored in advance may be one. However, since the QH curve and the QA curve do not completely match the pump similarity law, a plurality of operating frequencies are used. Save the characteristic data in, select the data closest to the current operating frequency from the characteristic data, perform the above-mentioned characteristic data calculation process, more accurately determine the QH curve and QA curve, as a result It is possible to accurately grasp the pump operating state.

In the first and second embodiments, since it is not necessary to store pump characteristic data in advance, it is simple, and the step-out determination is performed based on the change during operation. Although superior in that it is not affected, in the third embodiment, abnormalities can be accurately detected in a short time by comparing the actual measured operating state with the pump characteristic data measured and stored in advance as described above. Is superior in that it can be detected.

Claims

A pump unit having an impeller provided in the pump casing;
A synchronous motor for rotationally driving the impeller;
An inverter that controls the synchronous motor, and a pump system comprising:
The inverter is
A signal input unit for inputting a signal from a pressure detection means for detecting a water pressure provided on the discharge side of the pump unit;
An arithmetic processing unit for determining the rotational speed of the synchronous motor;
A storage unit for storing control parameters necessary for the calculation performed by the calculation processing unit;
A power converter that supplies a driving current to the synchronous motor;
Have
The arithmetic processing unit performs a process of stopping and restarting the synchronous motor when a change in pressure of a predetermined value or more is detected by a signal from the pressure detection unit, and the synchronization is performed at a first restart. A pump system characterized in that, when the electric motor does not start normally, the second restart is performed at an increase rate different from the increase rate of the rotational speed of the synchronous motor at the first restart.
The pump system according to claim 1, wherein
In the arithmetic processing unit, after detecting a change in pressure of a predetermined value or more and restarting the synchronous motor, in the first restart, when the detection value of the pressure detection means returns to the normal range, the pressure A pump system characterized in that the cause of the change is a step-out and a signal indicating the step-out is output to the outside.
The pump system according to claim 1, wherein
The arithmetic processing unit detects a pressure drop equal to or greater than a predetermined value based on a signal from the pressure detection means, and stops and restarts the synchronous motor when the load current value is equal to or less than a predetermined value. If the synchronous motor does not start normally after the first restart, the second restart is performed at an increase rate different from the increase rate of the synchronous motor speed at the first restart. A pump system characterized by performing.
The pump system according to claim 1, wherein
The arithmetic processing unit outputs a failure signal when the number of restarts exceeds a predetermined number.
The pump system according to claim 1, wherein
The increase rate of the rotation speed of the synchronous motor at the first restart is smaller than the increase rate of the rotation speed of the synchronous motor at the second restart.
A pump unit having an impeller provided in the pump casing;
A synchronous motor for rotationally driving the impeller;
An inverter that controls the synchronous motor, and a pump system comprising:
The inverter is
A signal input unit for inputting a signal from a pressure detection means for detecting a water pressure provided on the discharge side of the pump unit;
An arithmetic processing unit for determining the rotational speed of the synchronous motor;
A storage unit for storing control parameters necessary for the calculation performed by the calculation processing unit;
A power converter that supplies a driving current to the synchronous motor;
Have
In the storage unit, the number of rotations of the plurality of synchronous motors, the discharge-side pressure characteristic with respect to the discharge flow rate at the rotation number, and the load current value characteristic with respect to the discharge flow rate are stored in advance.
In the arithmetic processing unit, when the relationship between the actual rotational speed, the discharge side pressure, and the load current value deviates from the characteristics stored in the storage unit, the synchronous motor is stopped and restarted. When the synchronous motor does not start normally at the second restart, the second restart is performed at an increase rate different from the increase rate of the rotation speed of the synchronous motor at the first restart. And pump system.
The pump system according to claim 6, wherein
The arithmetic processing unit outputs a failure signal when the number of restarts exceeds a predetermined number.
The pump system according to claim 6, wherein
The pump system according to claim 1, wherein an increase rate of the rotation speed of the synchronous motor at the first restart is smaller than an increase rate of the rotation speed of the synchronous motor at the second restart.