Selective fluid pumping system

A control system may include circuitry configured to: a deterioration level estimation unit configured to estimate deterioration levels of pumping devices based on information about driving forces of the pumping devices; a selection unit configured to select a pumping device from the pumping devices based on a comparison of the estimated deterioration levels estimated by the deterioration level estimation unit; and a pumping control unit configured to control the selected pumping device selected by the selection unit to pump fluid.

BACKGROUND

The present disclosure relates to a fluid pumping system, a power conversion system, a power conversion apparatus, and a fluid pumping method.

2. Description of the Related Art

Japanese Unexamined Patent Publication No. Hei 9(1997)-126144 discloses a process for operating a variable speed feed water pump, including: additionally supplying a first pump when an operation speed of the second pump continues to be an allowable maximum operation speed for a predetermined time or more; and stopping the operation of the second pump when a state in which a discharge amount of the second pump is small continues for a predetermined time or more.

SUMMARY

Disclosed herein is an example control system including circuitry configured to: estimate deterioration levels of pumping devices based on information about driving forces of the pumping devices; select a pumping device from the pumping devices based on a comparison of the estimated deterioration levels; and control the selected pumping device to pump fluid.

Additionally, an example fluid pumping system is disclosed herein. The fluid pumping system includes: the control system; and the pumping devices configured to be controlled by the control system.

Additionally, an example fluid pumping method is disclosed herein. The fluid pumping method includes: estimating a deterioration levels of pumping devices based on information about driving forces of the pumping devices; selecting a pumping device from the pumping devices based on a comparison of the estimated deterioration levels; and controlling the selected pumping device to pump fluid.

DETAILED DESCRIPTION

Hereinafter, with reference to the drawings, the same elements or similar elements having the same function are denoted by the same reference numerals, and redundant description will be omitted.

Fluid Pumping System

The fluid pumping system1shown inFIG.1is a pumping system for increasing the pressure of a water supply line to a water supply consumer facility such as a faucet or a shower head. The fluid pumping system1includes electrical pumping devices10, check valves40, a pressure sensor30, and a power conversion system20.

The pumping device10(electrical machine) pumps water (fluid) by electric power. For example, the pumping device10includes a pump11and a motor12. The pump11has a suction port11aconnected to the primary side water supply pipe91and a discharge port11bconnected to the secondary side water supply pipe92. The “primary side” means the upstream side of the fluid pumping system1, and the “secondary side” means the downstream side of the fluid pumping system1. The pump11is configured to pump fluid from the primary side water supply pipe91(primary line) to the secondary side water supply pipe92(secondary line). The pump11incorporates a rotary pumping body such as an impeller or a reciprocating pumping body such as a diaphragm, and pumps water from the suction port11ato the discharge port11bby rotation of the rotary pumping body or reciprocation of the reciprocating pumping body. This pumps water from the primary side water supply pipe91to the secondary side water supply pipe92.

The motor12converts electric power into motive power to drive the pump11. For example, the motor12is a synchronous motor or an induction motor that converts AC power into rotational torque. The object to be pumped by the pumping device10may be a liquid other than water. The object to be pumped by the pumping device10is not necessarily limited to a liquid. For example, the pumping device10may include a ventilator (for example, a fan or a blower) for pumping gas instead of the pump11for liquid pumping. InFIG.1, two pumping devices10are illustrated for convenience, but the number of pumping devices10is not limited thereto. The fluid pumping system1may comprise three or more pumping devices10.

The check valves40are interposed between the suction ports11aand the secondary side water supply pipe92to prevent backflow of water from the secondary side water supply pipe92to the primary side water supply pipe91. The pressure sensor30detects the secondary side pressure of the fluid pumping system1. For example, the pressure sensor30is connected to the secondary side water supply pipe92on the downstream side of the check valves40.

The power conversion system20causes at least one of the pumping devices10to pump water from the primary side water supply pipe91to the secondary side water supply pipe92as the pressure detected by the pressure sensor30decreases. The power conversion system20is configured to estimate deterioration levels of the pumping devices10based on information about driving forces of the one pumping devices10, select a pumping device10from the pumping devices10based on the estimated deterioration levels, and control the selected pumping device10to pump water.

For example, the power conversion system20includes a plurality of power conversion apparatuses100and a controller200. The plurality of power conversion apparatuses100convert power of a power source (e.g., a power system or a battery) into driving power (e.g., AC power) and supply the driving power to the pumping devices10, respectively. Hereinafter, in the description of each power conversion apparatus100, the pumping device10to which power is supplied by the power conversion apparatus100is referred to as a “corresponding pumping device10”.

The power conversion apparatus100is configured to output a driving current to the motor12of the corresponding pumping device10to operate the corresponding pumping device10when the corresponding pumping device10is selected from the pumping devices10based on the deterioration levels of the pumping devices10, and estimate the deterioration level of the corresponding pumping device10based on information about a driving force of the corresponding pumping device10(e.g., a driving force applied to the pump11by the motor12). Since each of the plurality of power conversion apparatuses100is configured to estimate the deterioration level of the corresponding pumping device10, the plurality of power conversion apparatuses100comprise circuitry configured to estimate deterioration levels of pumping devices10.

The controller200selects at least one pumping device10from the pumping devices10as the pressure detected by the pressure sensor30decreases, and outputs a driving current from the power conversion apparatus100corresponding to the at least one pumping device10to the motor12so that water is pumped by the selected at least one pumping device10. The controller200is configured to select the at least one pumping device10from the pumping devices10based on the deterioration level estimated by the at least one power conversion apparatus100. For example, the controller200is configured to select a pumping device1from the pumping devices10based on a comparison of deterioration levels estimated by the plurality of power conversion devices100.

FIG.2is a block diagram illustrating a functional configuration of the power conversion system20. The power conversion apparatus100includes a power conversion unit113, a speed control unit111, a current control unit112, a current detection unit114, a deterioration level estimation unit115, a pumping control unit116, a force data acquisition unit117, and a force data holding unit118as functional modules.

The power conversion unit113outputs driving power to the motor12. For example, the power conversion unit113outputs an AC voltage having a frequency corresponding to the operation speed of the motor12to the motor12at a voltage amplitude corresponding to the voltage command. For example, the power conversion unit113generates the AC voltage by pulse width modulation (PWM). The power conversion unit113may be an inverter that converts DC power of a DC bus into AC power to generate drive power, or may be a matrix converter that performs bidirectional power conversion between AC power on the AC power supply side and AC power on the motor12side.

The speed control unit111causes the speed control unit111to output the AC voltage to the motor12so that the operation speed of the motor12follows the target speed. For example, the speed control unit111calculates a current command (torque command) for reducing the deviation between the target speed and the operating speed of the motor12.

The current control unit112calculates a voltage command for reducing a deviation between the current command calculated by the speed control unit111and the driving current being output to the motor12, and outputs the voltage command to the power conversion unit113. Accordingly, the power conversion unit113outputs, to the motor12, an AC voltage for causing the operation speed of the motor12to follow the target speed.

The current detection unit114detects the driving current output from the power conversion unit113to the motor12and feeds back the driving current to the current control unit112. The speed control unit111, the current control unit112, the power conversion unit113, and the current detection unit114repeat the above-described processing at a predetermined control cycle.

The force data acquisition unit117acquires information (hereinafter, force data) on a driving force of the corresponding pumping device10for each control period. The information on the driving force (hereinafter, force data) may be any information as long as it is correlated with the driving force to such an extent that the magnitude of the driving force can be grasped based on the information. For example, since the magnitude of the driving current is correlated (substantially proportional) to the magnitude of the driving force, the magnitude of the driving current corresponds to the force data. Since the magnitude of the driving current corresponds to the force data, the force data acquisition unit117may acquire the force data associated with the driving current. The force data acquisition unit117may acquire the force data includes current information indicating the driving current of the corresponding pumping device10. For example, the force data acquisition unit117acquires the magnitude of the driving current detected by the current detection unit114as force data. The force data acquisition unit117may acquire the magnitude of the current command calculated by the speed control unit111as force data. When the pumping device10includes a driving force sensor (e.g., a torque sensor), the force data acquisition unit117may acquire a detected value of the torque sensor as force data. The force data holding unit118stores the force data acquired by the force data acquisition unit117in time series.

The deterioration level estimation unit115estimates the deterioration level of the corresponding pumping device10based on the force data. The deterioration level estimation unit115calculates an amplitude index value corresponding to the amplitude of the oscillation of the force data as an example of estimating the deterioration level. Here, “corresponding” means a correlation in which the amplitude index value increases or decreases in accordance with an increase or decrease in amplitude. The amplitude index value may be any value as long as it “corresponds” to the amplitude.

In the pumping device10, the amplitude of the oscillation of the force data tends to increase as the deterioration level of the power transmission system from the motor12to the pump11increases. Therefore, calculating the amplitude index value corresponds to estimating the deterioration level of the pumping device10. Examples of the deterioration of the power transmission system include deterioration of a bearing of a torque transmission shaft.

For example, the deterioration level estimation unit115derives the amplitude of the oscillation of the force data as the amplitude index value based on a plurality of force data acquired from a predetermined period before the acquisition time of the force data to the acquisition time. The amplitude may be a width from a negative peak to a positive peak, or may be a half of a width from a negative peak to a positive peak. The oscillation is an oscillation in a steady operation of the pumping device10. The steady operation means an operation state in which water is filled in the pump11and the driving speed of the pump11substantially coincides with the target speed. Substantially coincident means that the difference between the driving speed and the target speed is within a negligible error range. The deterioration level estimation unit115may calculate the difference between the maximum value and the minimum value of the force data within a predetermined period as the amplitude, or may calculate the amplitude by fast Fourier transform (FFT) or the like. The deterioration level estimation unit115may calculate the amplitude of a predetermined frequency component by FFT, or may calculate an average value, a maximum value, or the like of the amplitude in a frequency component of a predetermined band.

The deterioration level estimation unit115may calculate, as the amplitude index value, the difference between the force data and the trend value of the force data based on the past force data acquired from a predetermined period before the acquisition time of the force data to the acquisition time. For example, the deterioration level estimation unit115removes a DC component from the past force data as necessary with respect to the latest force data, and further performs low-pass type filtering to calculate the trend value.

As an example of the low-pass type filtering, there is a finite impulse response type filtering. When first order filtering of the finite impulse response method is used, the trend value is derived by the following equation.
Y=A·X[k]+(1−A)·X[k−1]  (1)Y: trend valueX[k]: latest force dataX[k−1]: previously acquired force dataA: filter coefficient

When second order filtering of the finite impulse response method is used, the trend value is derived by the following equation.
Y=A·X[k]+B·X[k−1]+(1−A−B)·X[k−2]  (2)Y: trend valueX[k]: latest force dataX[k−1]: previously acquired force dataX[k−2]: acquired force data two times beforeA and B: filter coefficients.

The deterioration level estimation unit115does not necessarily use the latest force data for calculating the trend value, and may calculate the trend value based on the past force data. For example, X[k] may be force data acquired several times (for example, one time) before the latest.

When the corresponding pumping device10is selected from the pumping devices10based on the deterioration level estimated by the deterioration level estimation unit115, the pumping control unit116controls the power conversion unit113to output a driving current to the motor12so as to operate the corresponding pumping device10. For example, when the corresponding pumping device10is selected, the pumping control unit116causes the speed control unit111to start control (control for causing the operating speed of the motor12to follow the target speed).

The controller200includes, as functional modules, a deterioration level information acquisition unit211, a deterioration level information holding unit212, an operation history holding unit213, a pressure information acquisition unit214, a selection unit215, and a pumping control unit216. The deterioration level information acquisition unit211acquires the estimation result of the deterioration level by the deterioration level estimation unit115of each power conversion apparatus100. The deterioration level information holding unit212stores the estimation result of the deterioration level acquired by the deterioration level information acquisition unit211for each power conversion apparatus100. The operation history holding unit213stores operation history information of each pumping device10. The operation history information includes, for example, a pumping start time and a pumping stop time of water by the pumping device10.

The pressure information acquisition unit214acquires information on the secondary side pressure (a pressure in the secondary line) in the pumping devices10(for example, a value detected by the pressure sensor30). The selection unit215selects at least one pumping device10from the pumping devices10in response to the secondary side pressure falling below a predetermined lower limit value (hereinafter, pressure lower limit value). For example, the selection unit215may select the pumping device10in response to determining that the secondary side pressure is lower than the lower limit value. Hereinafter, pumping device10selected by selection unit215is referred to as “pumping device10for normal operation”.

The selection unit215selects the pumping device10for normal operation based on the deterioration levels stored in the deterioration level information holding unit212. The pumping devices10may include a first pumping device and a second pumping device10, and the selection unit215may be configured to select the first pumping device10as the pumping device10for normal operation, in response to determining that a deterioration level of the first pumping device is lower than a deterioration level of the second pumping device10. For example, the selection unit215selects the pumping device10for normal operation to make the operation period of the pumping device10having a higher deterioration level shorter than the operation period of the pumping device10having a lower deterioration level. For example, the selection unit215selects the pumping device10having the lowest deterioration level from the pumping devices10.

The selection unit215may select the pumping device10for normal operation based on a predetermined selection criterion and the deterioration level stored in the deterioration level information holding unit212. For example, the selection unit215may select the pumping device10for normal operation based on a first selection criterion based on the deterioration level and a second selection criterion determined separately from the first selection criterion. For example, the selection unit215may select the pumping device10for normal operation based on the first selection criterion used to compare the deterioration levels, and based on the second selection criterion different from the first selection criterion. For example, the first selection criterion is set to select a pumping device10having a lower deterioration level over a pumping device10having a higher deterioration level. For example, the first selection criterion may be predetermined so that the first pumping device10is selected if a deterioration level of the first pumping device10is lower than a deterioration level of the second pumping device.

The second selection criterion may be used to compare cumulative operation periods of the pumping devices10. For example, the second selection criterion is set to select the pumping device10having a shorter cumulative operation period over the pumping device10having a longer cumulative operation period. For example, the second selection criterion may be predetermined so that the first pumping device10is selected if a cumulative operation period of the first pumping device10is shorter than a cumulative operation period of the second pumping device10. The cumulative operation period is substantially correlated with the cumulative operation times. Therefore, selecting the pumping device10with a shorter cumulative operation period over the pumping device10with a longer cumulative operation period includes selecting the pumping device10with fewer cumulative operation times over the pumping device10with more cumulative operation times.

The first selection criterion may prioritize a selection of the pumping device10in response to determining that the pumping device10has a lower deterioration level compared to one or more of the pumping devices10, and the second selection criterion may prioritize a selection of the pumping device10in response to determining that the pumping device10has a shorter cumulative operation period compared to the one or more pumping devices10. The selection unit215may calculate priority levels of the pumping devices10based on a combination of the first selection criterion and the second selection criterion and select the pumping device10in response to determining that the pumping device10has a higher priority level compared to the one or more pumping devices10. For example, the selection unit215derives the priority of each of the pumping devices10based on both the first selection criterion and the second selection criterion, and selects the pumping device10having the highest priority. For example, the selection unit215derives the priority based on a function, a table, or the like defined such that the priority of the pumping device10having a lower deterioration level is higher than the priority of the pumping device10having a higher deterioration level when there is no difference in the cumulative operation period, and the priority of the pumping device10having a short cumulative operation period is higher than the priority of the pumping device10having a long cumulative operation period when there is no difference in the deterioration level.

The selection unit215may select the pumping device10for normal operation based on the predetermined selection criterion, and select the pumping device10for normal operation based on the deterioration level when the deterioration level of any of the pumping devices10exceeds a predetermined threshold value (hereinafter, referred to as a reference change over threshold value). For example, the selection unit215may calculate priority levels of the pumping devices10based on the second selection criterion if each of the deterioration levels is lower than a first threshold value, calculate the priority levels based on the first selection criterion if at least one of the deterioration levels is higher than the first threshold value; and select the pumping device in response to determining that the pumping device10has a higher priority level compared to the one or more pumping devices10. For example, the selection unit215may select the pumping device10for normal operation based on the second selection criterion when the maximum value of the deterioration level in the pumping devices10(hereinafter, the maximum value of the deterioration level) is below the reference change over threshold value, and select the pumping device10for normal operation based on the first selection criterion when the maximum value of the deterioration level is above the reference change over threshold value.

The selection unit215may change the weight of the first selection criterion with respect to the second selection criterion as the deterioration level increases. For example, the selection unit215may increase a weight of the first selection criterion, in calculating the priority levels, in response to an increase of one of the deterioration levels. For example, the selection unit215may calculate the priority levels based on a combination of the first selection criterion and the second selection criterion if each of the deterioration levels is lower than a second threshold value that is higher than the first threshold value and at least one of the deterioration levels is higher than the first threshold value; and calculate the priority levels based on the first selection criterion if at least one of the deterioration levels is higher than the second threshold value. For example, the selection unit215may change the weight of the first selection criterion with respect to the second selection criterion based on the relationship between the plurality of levels of reference change over threshold values and the maximum value of the deterioration level. For example, the selection unit215may select the pumping device10for normal operation based only on the second selection criterion when the maximum value of the deterioration level is below the minimum reference change over threshold value, increase the weight of the first selection criterion for the second selection criterion whenever the maximum value of the deterioration level exceeds the reference change over threshold value, and select the pumping device10for normal operation based only on the first selection criterion when the maximum value of the deterioration level exceeds the maximum reference change over threshold value. The selection unit215deselects the pumping device10for normal operation in response to the secondary side pressure exceeding a predetermined upper limit value (hereinafter, pressure upper limit value). For example, the selection unit215may deselect the pumping device10in response to determining that the secondary side pressure is higher than the upper limit value.

When the pumping device10for normal operation is selected, the pumping control unit216outputs a driving start command to the power conversion apparatus100corresponding to the pumping device10for normal operation. Accordingly, the pumping control unit116of the power conversion apparatus100starts pumping water by the pumping device10for normal operation. That is, the pumping control unit216controls the pumping device10selected by the selection unit215to pump water.

When the selection of the pumping device10for normal operation is released, the pumping control unit216outputs a driving stop command to the power conversion apparatus100corresponding to the pumping device10for normal operation. Accordingly, the pumping control unit116of the power conversion apparatus100stops the pumping of water by the pumping device10for normal operation.

The controller200may be configured to cause at least one pumping device10that is not selected by the selection unit215to also pump water when a secondary side pressure of the pumping device10for normal operation (e.g., a detected value by the pressure sensor30) is insufficient. For example, the controller200further includes an additional selection unit217.

The additional selection unit is configured to select an additional pumping device10from the pumping devices10in response to determining that the secondary side pressure is lower than a target value equal to or higher than the lower limit value while the pumping device10is controlled to pump fluid from the primary side water supply pipe91to the secondary side water supply pipe92. For example, the additional selection unit217selects at least one pumping device10not selected by the selection unit215from the pumping devices10when the secondary side pressure in the pumping device10for normal operation is insufficient. Hereinafter, the pumping device10selected by the additional selection unit217is referred to as “pumping device10for additional operation”. For example, the additional selection unit217selects the pumping device10for additional operation when the detected value by the pressure sensor30is below the target value (hereinafter, referred to as an additional threshold value) although the pumping device10for normal operation is pumping water. The additional threshold value may be any value that is greater than or equal to the pressure lower limit value and less than the pressure upper limit value. The additional selection unit217cancels the selection of the pumping device10for additional operation in response to the secondary side pressure exceeding the pressure upper limit value.

When the additional selection unit217selects the pumping device10for additional operation, the pumping control unit216controls both the pumping device10for normal operation and the pumping device10for additional operation to concurrently pump fluid from the primary side water supply pipe91to the secondary side water supply pipe92. For example, the pumping control unit216outputs a driving start command to the power conversion apparatus100corresponding to the pumping device10for additional operation. Accordingly, the pumping control unit116of the power conversion apparatus100starts controlling the pumping device10for additional operation to pump water. That is, the pumping control unit216controls the pumping device10for additional operation to pump water while the pumping control unit116for normal operation controls the pumping device10for normal operation to pump water. When the selection of the pumping device10for additional operation is released, the pumping control unit216outputs a driving stop command to the power conversion apparatus100corresponding to the pumping device10for additional operation. Accordingly, the pumping control unit116of the power conversion apparatus100stops the pumping of water by the pumping device10for additional operation.

The pumping device10for additional operation may have a higher deterioration level compared to the pumping device10for normal operation. For example, the additional selection unit217may be configured to select a pumping device10even if the pumping device10has a higher deterioration level compared to the pumping device10for normal operation. For example, when the selection unit215does not select the pumping device10whose deterioration level exceeds a predetermined threshold value, the additional selection unit217may select the pumping device10whose deterioration level exceeds the threshold value. For example, the additional selection unit217may be configured to select a pumping device10even if a deterioration level of the pumping device10exceeds the maximum reference change over threshold value.

The controller200may be further configured to notify a user of the deterioration level of the at least one pumping device10. For example, the controller200further includes a deterioration notification unit218. The deterioration notification unit218notifies the user that the deterioration level of at least one pumping device10exceeds a predetermined threshold value (hereinafter, referred to as a notification threshold value) through a display device. In some examples, the deterioration notification unit218notifies the user through the display device that the maximum value of the deterioration level exceeds the notification threshold value. Examples of the display device include a liquid crystal monitor and an alarm lamp. The alert threshold value may be higher than the reference change over threshold value described above.

The deterioration notification unit218may be configured to notify the user of a change in the relationship between the alert threshold value and the maximum value of the deterioration level in multiple stages. For example, the deterioration notification unit218may be configured to notify the user of the increase in the deterioration level each time the deterioration level being increased exceeds the alert threshold value. The increase in the deterioration level can be notified by a change in the display content on the liquid crystal monitor, a change in the color of the alarm lamp, or the like.

The deterioration notification unit may be configured to further notify in which pumping device10the deterioration level exceeds the alert threshold value. In which pumping device10the deterioration level exceeds the alert threshold value can be notified by displaying identification information of the pumping device10exceeding the alert threshold value on the liquid crystal monitor, for example. In addition, in which pumping device10the deterioration level exceeds the alert threshold value can be notified by which alarm lamp provided for each pumping device10is turned on.

FIG.3is a block diagram illustrating a hardware configuration of the power conversion system20. As shown inFIG.3, the power conversion apparatus100includes a switching circuit120, a current sensor130, and control circuitry140.

The switching circuit120operates in accordance with a command from the control circuitry140(for example, an electric signal from the input/output port144), and functions as the power conversion unit113. For example, the switching circuit120outputs the driving power to the motor12by switching on and off a plurality of switching elements in accordance with an electric signal (for example, a gate signal) from the input/output port144. The switching element is, for example, a power metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT). The current sensor130operates in accordance with a command from the control circuitry140(for example, an electric signal from the input/output port144), and functions as the above-described current detection unit114. The current sensor130detects the output current from the switching circuit120to the motor12.

The control circuitry140includes one or more processors141, memory142, storage143, and an input/output port144. The storage143includes a computer-readable storage medium such as a nonvolatile semiconductor memory. The storage143stores a program for causing the power conversion apparatus100to output a driving current to the motor12of the corresponding pumping device10so as to operate the corresponding pumping device10when the corresponding pumping device10is selected from the pumping devices10based on the deterioration level of the pumping device12, and to estimate the deterioration level of the corresponding pumping device10based on information on the driving force of the corresponding pumping device10(e.g., the driving force applied to the pump11by the motor12). For example, the storage143stores a program for configuring the functional modules of the power conversion apparatus100.

The memory142temporarily stores a program loaded from the storage medium of the storage143and an operation result by the processor141. The processor141executes the program in cooperation with the memory142to configure each functional module of the power conversion apparatus100. The input/output port144has a terminal block of an input power supply, and performs input/output of an electric signal between the switching circuit120, the current sensor130, and the controller200according to a command from the processor141.

The controller200includes circuitry220. The circuitry220includes one or more processors221, a memory222, a storage223, a display device224, and an input/output port225. The storage223includes a computer-readable storage medium such as a nonvolatile semiconductor memory. The storage223stores a program for causing the controller200to select at least one pumping device10from the pumping devices10based on the deterioration level estimated by the at least one power conversion apparatus100, and output a driving current from the power conversion apparatus100corresponding to the at least one pumping device10to the motor12so that water is pumped by the selected at least one pumping device10. For example, the storage223stores a program for configuring the functional modules of the controller200described above.

The storage143of the power conversion apparatus100and the storage223of the controller200correspond to the storage of the power conversion system20, and the storage stores a program for causing the power conversion system20to estimate the deterioration level of one pumping device10based on the information on the driving force of the one pumping device10, select at least one pumping device10from the pumping devices10based on the estimated deterioration level, and control the selected at least one pumping device10to pump water.

The memory222temporarily stores a program loaded from the storage223, an operation result by the processor221, and the like. The processor221executes the application in cooperation with the memory222. The display device224includes, for example, a liquid crystal monitor, an alarm lamp, and the like, and is used for displaying information to the user. The input/output port225inputs and outputs an electric signal between the pressure sensor30and the power conversion apparatus100in accordance with a command from the processor221.

The functions of the control circuitry140and the circuitry220are not necessarily configured by programs. For example, at least a part of the functions of the control circuitry140and the circuitry220may be configured by dedicated logic circuitry or an application specific integrated circuit (ASIC) in which the dedicated logic circuitry is integrated.

The configuration of the power conversion system20described above is merely an example, and can be changed. For example, in the above example, one controller200is provided for a plurality of power conversion apparatuses100, but the present configuration is not limited thereto, and a plurality of controllers200may be provided for a plurality of power conversion apparatuses100, respectively (seeFIG.4). In this case, at least one of the plurality of controllers200can constitute a functional module of the controller200described above. Further, the functional module of the controller200may be configured by any of the plurality of power conversion apparatuses100. In this case, the controller200may be omitted (seeFIG.5).

Fluid Pumping Method

Next, as an example of the fluid pumping method, an example control procedure of the pumping devices10executed by the power conversion system20will be described. The control procedure includes: estimating a deterioration level of one of the pumping devices10based on information about a driving force of the one pumping device10, selecting at least one pumping device10from the pumping devices10based on the estimated deterioration level, and pumping water by the selected at least one pumping device10.

FIG.6is a flowchart illustrating a control procedure of the pumping devices10. As shown inFIG.6, the power conversion system20first executes operation S01. In operation S01, the pressure information acquisition unit214acquires the detected value by the pressure sensor30as the information of the secondary side pressure, and the selection unit215checks whether the detected value is below the pressure lower limit value. When it is determined that the detected value by the pressure sensor30is not lower than the pressure lower limit value, the power conversion system20executes operation S01again. Thereafter, operation S01is repeated until the detected value by the pressure sensor30falls below the pressure lower limit value.

When it is determined that the detected value by the pressure sensor30is lower than the pressure lower limit value, the power conversion system20executes operations S02, S03, S04, and S05. In operation S02, the selection unit215selects the pumping device10for normal operation based on the deterioration level stored in the deterioration level information holding unit212. In operation S03, the pumping control unit216outputs a driving start command to the power conversion apparatus100corresponding to the pumping device10for normal operation (hereinafter, power conversion apparatus100for normal operation). Accordingly, the pumping control unit116of the power conversion apparatus100starts the pumping of water by the pumping device10for normal operation. In operation S04, the force data acquisition unit117of the power conversion apparatus100for normal operation starts acquiring force data.

In operation S05, the pressure information acquisition unit214acquires the detected value by the pressure sensor30as the information of the secondary side pressure, and the selection unit215checks whether the detected value exceeds the pressure upper limit value. If it is determined in operation S05that the detected value does not exceed the pressure upper limit value, the power conversion system20executes operation S06. In operation S06, the additional selection unit217checks whether the value detected by the pressure sensor30is below the additional threshold value.

If it is determined in operation S06that the detected value is below the additional threshold value, the power conversion system20executes operations S07, S08, and S09. In operation S07, the additional selection unit217selects the pumping device10for additional operation from the pumping devices10. In operation S08, the pumping control unit216outputs a driving start command to the power conversion apparatus100corresponding to the pumping device10for additional operation (hereinafter referred to as the power conversion apparatus100for additional operation). Accordingly, the pumping control unit116of the power conversion apparatus100starts pumping water by the pumping device10for additional operation. In operation S09, the force data acquisition unit117of the power conversion apparatus100for additional operation starts acquiring force data. Thereafter, the power conversion system20returns the process to operation S05.

If it is determined in operation S06that the detected value is not below the additional threshold value, the power conversion system20returns the process to operation S05without executing operations S07, S08, and S09. Thereafter, until the detected value by the pressure sensor30exceeds the pressure upper limit value, water pumping by the pumping device10for normal operation is continued, and water pumping by the pumping device10for additional operation is also continued as necessary.

If it is determined in operation S05that the detected value exceeds the pressure upper limit value, the power conversion system20executes operation S11. In operation S11, the selection unit215cancels the selection of the pumping device10for normal operation. Accordingly, the pumping control unit116of the power conversion apparatus100for normal operation stops the pumping of water by the pumping device10for normal operation. If the pumping device10for additional operation is selected, the additional selection unit217cancels the selection of the pumping device10for additional operation. Accordingly, the pumping control unit116of the power conversion apparatus100for additional operation stops the pumping of water by the pumping device10for additional operation.

Next, the power conversion system20executes operations S12and S13. In operation S12, the deterioration level estimation unit115of the power conversion apparatus100estimates the deterioration level of the pumping device10for normal operation based on the force data stored in the force data holding unit118of the power conversion apparatus100for normal operation. When the pumping device10for additional operation is selected, the deterioration level estimation unit115of the power conversion apparatus100for additional operation further estimates the deterioration level of the pumping device10for additional operation based on the force data stored in the force data holding unit118of the power conversion apparatus100for additional operation. In operation S13, the deterioration level information acquisition unit211acquires the estimation result of the deterioration level by the deterioration level estimation unit115of the power conversion apparatus100for the normal operation and the additional operation, and stores the estimation result in the deterioration level information holding unit212. The power conversion system20repeats the above processing.

In the above-described procedure, the deterioration level is estimated once after the operation of the pumping device10is stopped, but the timing of estimating the deterioration level is not necessarily limited thereto. For example, the estimation of the deterioration level may be repeated during driving. In this case, the pumping device10to be operated may be switched during operation in accordance with an increase in the deterioration level.

As described above, the fluid pumping system1includes the pumping devices10for pumping water, the deterioration level estimation unit115configured to estimate a deterioration level of one pumping device10based on information about a driving force of the one pumping device10, the selection unit215configured to select at least one pumping device10from the pumping devices10based on the deterioration level estimated by the deterioration level estimation unit115, and the pumping control unit216configured to control the at least one pumping device selected by the selection unit215to pump water.

According to the fluid pumping system1, since the selection criterion is automatically changed based on the deterioration level, the pumping device10having a lower deterioration level may be preferably operated. This makes it possible to suppress the progress of deterioration of the pumping device10having a higher deterioration level. Therefore, the frequency of maintenance may be reduced. In addition, suppressing the progress of deterioration of the pumping device10having a higher deterioration level can contribute to improvement of operation efficiency, suppression of vibration, suppression of noise, and the like.

The selection unit215may be further configured to select at least one pumping device10based on the predetermined selection criterion and the deterioration level estimated by the deterioration level estimation unit115. In this case, at a stage where deterioration of any pumping device10has not progressed, the pumping devices10may be selectively used according to desired conditions by setting selection criterion.

The selection unit215may be further configured to select at least one pumping device10based on the deterioration level and selection criterion determined to select the pumping device10having a shorter cumulative operation period over the pumping device10having a longer cumulative operation period.

The selection unit215may be further configured to select at least one pumping device10based on the selection criterion, and to select at least one pumping device10based on the deterioration level when a deterioration level of any of the pumping devices10exceeds a predetermined threshold value.

The selection unit215may be further configured to select at least one pumping device10to make an operation period of the pumping device10having a higher deterioration level shorter than an operation period of the pumping device10having a lower deterioration level. In this case, the operation of the pumping device10having a lower deterioration level may be prioritized.

The fluid pumping system1may further include an additional selection unit217configured to select at least one pumping device10not selected by the selection unit215from the pumping devices10when a secondary side pressure of the pumping device10selected by the selection unit215is insufficient. The pumping control unit216may be further configured to control the pumping device10selected by the additional selection unit217to pump water while controlling the pumping device10selected by the selection unit215to pump water. In this case, by suppressing the progress of deterioration in the pumping device10having a higher deterioration level, the usable period of the pumping device10as an additional operation object can be extended. Therefore, in a configuration in which an operation mode not using an additional operation object (hereinafter, referred to as a normal operation mode) and an operation mode using an additional operation object (hereinafter, referred to as a parallel operation mode) are switched, the deterioration progress of the pumping device10having a higher deterioration level may be suppressed.

The additional selection unit217may be further configured to select the pumping device10having a higher deterioration level than the pumping device10selected by the selection unit215. The operation period of the pumping device10for additional operation is shorter than the operation period of the pumping device10to be operated. Therefore, by allocating the pumping device10having a higher deterioration level to the additional operation object, the pumping device10may be used while suppressing the progress of deterioration of the pumping device10having a higher deterioration level.

The selection unit215may be further configured not to select the pumping device10having a deterioration level exceeding the predetermined threshold value, and the additional selection unit217may be further configured to select the pumping device10having the deterioration level exceeding the threshold value. In this case, the progress of deterioration of the pumping device10having a higher deterioration level may be suppressed and the pumping device10may be used as an additional operation object.

The fluid pumping system1may further comprise a deterioration notification unit218configured to notify the user that the deterioration level exceeds a predetermined threshold value. In this case, the maintenance timing may be more reliably optimized.

The deterioration notification unit218may be further configured to notify which of the pumping devices10the deterioration level exceeds the threshold. In this case, the efficiency of the maintenance work may be improved.

The pumping device10may be electrical, and the deterioration level estimation unit115may be further configured to estimate the deterioration level of the pumping device10based on the driving current of the pumping device10.

Although certain procedures or operations are described herein as being performed sequentially or in a particular order, in some examples one or more of the operations may be performed in a different order, in parallel, simultaneously with each other, or in an overlapping manner. Additionally, in some examples, one or more of the operations may be optionally performed or, in some cases, omitted altogether.

We claim all modifications and variations coming within the spirit and scope of the subject matter claimed herein.