JP5606989B2 - Variable speed drive device and water supply device - Google Patents

Description

  The present invention relates to a variable speed drive apparatus and a water supply apparatus suitable for indirectly controlling the pressure of a water supply pump that is rotationally driven based on the inverter frequency of the variable speed drive apparatus and its current characteristics.

  The water supply system is a variable speed drive (an inverter is used to drive an induction motor, and a controller for this is used to drive a permanent magnet motor. This controller is also based on an inverter. It is comprised with the water supply pump driven by. The variable speed drive device has an integrated structure with the water supply pump and a separate structure, and has an inverter function including a storage unit, setting means, current detection means, voltage and frequency output means. Yes.

  There exists patent document 1 as a prior art of these water supply apparatuses. Patent Document 1 describes a turbomachine control method for controlling the rotation speed of a turbomachine that controls discharge pressure with an inverter, and corresponds to the relationship between the target discharge pressure and the rotation speed for controlling the discharge pressure to a predetermined target value. The relationship between the target current and the rotational speed is stored in advance, the value of the internal current of the inverter corresponding to the change in the discharge pressure is detected, and the magnitude of the detected value and the stored target current is determined. In comparison, the rotational speed of the turbomachine is increased or decreased.

  However, in the prior art shown in this patent document, data and functions fixedly stored in a table are used to obtain the target current from the inverter frequency, and it is not assumed that these are changed. In addition, the timing for updating the target current is not specified, and there is a possibility that an accurate target current cannot be obtained if it is updated during a shift. Furthermore, the target current value is a fixed value, and control may become unstable. In any case, when the target current is obtained from the inverter frequency, and the frequency is controlled so that the operating current becomes the target current and the discharge pressure is indirectly controlled to the predetermined target value, it corresponds to water pumps of various specifications In order to perform appropriate control, all the table data and the like are changed every time, and a considerably troublesome work is required.

JP-A-7-332277

  Accordingly, the present invention obtains a target current from the inverter frequency in a system in which the target current is obtained from the inverter frequency and the discharge pressure is indirectly controlled to a predetermined target value by controlling the frequency so that the operating current becomes the target current. It is an object of the present invention to provide a variable speed drive device and a water supply device that can automatically generate an arithmetic expression using parameters, generate an infinite number of arithmetic expressions, and can be easily applied to many models. In addition, the timing for updating the target current is specified to generate an arithmetic expression thereof, and a dead zone is provided for the target current to stabilize it.

In order to solve the above-mentioned problem, the present invention obtains a target current from an inverter frequency, and controls the inverter frequency so that the inverter current during operation becomes the target current to control the motor and the feed pump at a variable speed. In
An inverter for variable speed control of the water supply pump;
Current detection means for detecting the inverter current during operation;
A control unit for controlling the frequency of the inverter based on the detected inverter current ;
A setting unit for inputting parameters for generating an arithmetic expression for obtaining a target current;
A storage unit that stores a parameter input from the setting unit and an arithmetic expression generation program that generates an arithmetic expression using the parameter;
The storage unit stores, as parameters, a first current value and an inverter frequency, a second current value and an inverter frequency,
Wherein the control unit includes a first coordinate in the first current value and the first inverter frequency, the second coordinates respectively formed at the second current value and a second inverter frequency, through the two coordinates Generate a formula to calculate the target current from the inverter frequency,
In accordance with the comparison result between the value obtained by adding the dead band to the target current obtained by this arithmetic expression and the inverter current detected by the current detecting means, the following control is repeated and the target current is updated by the arithmetic expression while updating the target current. Control the frequency,
The update timing of the target current is triggered when the inverter frequency reaches the command frequency by the following control, and the width of the dead zone is set so that the current increase / decrease width does not exceed the target current region. It is characterized by being set.
1. If the detection current of the current detection means <target current ± α, the current inverter frequency is decelerated by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
2. If the detected current of the current detecting means> the target current ± α, the current inverter frequency is increased by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
3. No shift except above.

  Further, in the variable speed drive device described above, the motor is selected to have a capacity having a rated current smaller than the current at the maximum load of the water supply pump, and the inverter is selected to have a capacity having a rated current larger than the rated current of the motor. It is characterized by being.

  In the variable speed drive device described above, when the first inverter frequency forming the first coordinate is set to a frequency that satisfies the maximum load of the feed water pump, and the first current value is operated at the first inverter frequency. Water at the time of the maximum load of the feed water pump, the second inverter frequency forming the second coordinate as the frequency satisfying the minimum load of the feed water pump, and the second current value operating at the second inverter frequency The parameters are set by the setting unit so as to be the current at the minimum load (water volume 0) of the pump, and are stored in the storage unit.

  Further, in the variable speed drive device described above, the control unit obtains a target current by substituting the current frequency output from the inverter unit into the generated arithmetic expression, and updates the timing of the target current one time before. It is characterized by having changed from the current frequency to the current frequency and reaching it.

  Further, in the variable speed drive device described above, the control unit is triggered by the timing when the target current is updated when a predetermined time sufficient for the frequency output from the inverter unit to reach the current frequency has elapsed. It is characterized by that.

  Further, in the variable speed drive device described above, the control unit previously defines a parameter for generating an arithmetic expression for obtaining a target current for each model, and when applied to a specific target model, the control unit previously defines for each model. The parameter for the specific target model is selected from the parameters and written in the memory in advance.

In order to solve the above problems, the present invention provides a water supply device that obtains a target current from an inverter frequency and controls the inverter frequency so that the inverter current during operation becomes the target current to control the feed water pump at a variable speed.
A water supply pump,
An inverter for variable speed control of the water supply pump;
Current detection means for detecting the inverter current during operation;
A control unit for controlling the frequency of the inverter based on the detected inverter current ;
A setting unit for inputting parameters for generating an arithmetic expression for obtaining a target current;
A storage unit that stores a parameter input from the setting unit and an arithmetic expression generation program that generates an arithmetic expression using the parameter;
The storage unit stores, as parameters, a first current value and an inverter frequency, a second current value and an inverter frequency,
Wherein, the first coordinate in the first current value and the first inverter frequency, the second coordinates respectively formed at the second current value and a second inverter frequency, through the two coordinates Generate a formula to calculate the target current from the inverter frequency,
In accordance with the comparison result between the value obtained by adding the dead band to the target current obtained by this arithmetic expression and the inverter current detected by the current detecting means, the following control is repeated and the target current is updated by the arithmetic expression while updating the target current. Control the frequency,
The update timing of the target current is triggered when the inverter frequency reaches the command frequency by the following control, and the width of the dead zone is set so that the current increase / decrease width does not exceed the target current region. It is characterized by being set.
1. If the detection current of the current detection means <target current ± α, the current inverter frequency is decelerated by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
2. If the detected current of the current detecting means> the target current ± α, the current inverter frequency is increased by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
3. No shift except above.

  According to the present invention, an arithmetic expression for obtaining a target current from an inverter frequency is automatically generated using a parameter, and can be applied to many models so that an infinite number of arithmetic expressions can be generated. Since the target current is updated at an appropriate timing, the target current can be obtained correctly. Since the dead zone is provided for the target current update, the frequency control can be stabilized.

The system block diagram of the variable speed drive device and water supply apparatus of this invention Example. The water supply pump driving | operation characteristic figure of an Example. Explanatory drawing of the algorithm until it converges to the target electric current at the time of the change of the amount of water used of an Example. The parameter table for every model of an Example. The memory map of an Example. The driving | operation procedure flowchart of the drive system of an Example. Explanatory drawing of the algorithm at the time of starting of an Example. FIG. 7 is a supplementary operation procedure flowchart of FIG. 6.

  The best mode for carrying out the present invention will be described.

  An embodiment of a water supply apparatus of the present invention will be described with reference to the drawings.

  Embodiments of the present invention will be described below with reference to FIGS. Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a system configuration diagram of a water supply device and a variable speed drive device for a water supply device according to an embodiment of the present invention. 1 is a suction pipe connected to a water source, 2 and 6 are gate valves, 3 is a motor 4 driven by a motor 4 and discharges water from the water source to the discharge pipe 7 through the suction pipe 1, 5 is a check valve, Reference numeral 8 denotes a pressure gauge (for example, a Bourdon tube direct reading type). Although the motor 4 is shown as an induction motor in this embodiment, it may be a permanent magnet motor.

  R, S, and T are power sources, and ELB is an earth leakage breaker, and performs short circuit and earth leakage protection of the wiring after itself. The CU is a variable speed drive and has the following configuration and functions.

  CV is connected to commercial power supply R, S, T and is a converter that converts this to DC, C is a smoothing capacitor, P, N are DC power supply terminals generated by the converter CV, R is a shunt resistor, INV is a converter CV Is an inverter that reversely converts the DC power source converted into AC with a predetermined voltage and frequency, and these elements constitute the inverter unit INVU. The CPU is a microprocessor that performs various controls according to a program that will be described later, and M is a storage unit that includes an EEPROM (or flash memory), a RAM, and the like. A parameter for determining a target current that will be described later, and an operation that calculates the target current using the parameter. An arithmetic expression generation program for generating an expression and a program for operation control according to the generated arithmetic expression are stored.

  I / O is an input / output circuit unit, CT is a current detection means (inverter current may be detected indirectly by detecting the voltage across shunt resistor R), PWM is a PWM processing unit (pulse, wide, modulation) And commands to output the frequency and voltage based on the command frequency f (f command) to the inverter INV. The current detected from the current detection means CT is taken into the CPU via the input / output circuit unit I / O (processed into a level voltage signal that can be taken into the CPU).

  CONS is a console (setting unit, operator) having a display unit (for example, display of frequency, voltage, current, etc.) and a key operation unit (for example, tact switch, etc.). This is used to input parameters and signals for operation, stop, etc. (eg, tact switch at the key operation unit). S0 is an external operation command signal generator. For example, the operation is performed when the contact S0a is closed, and the operation is stopped when the contact S0a is opened.

  FIG. 2 is a characteristic diagram of the water supply pump of the variable speed drive device and the water supply device according to the embodiment of the present invention. . Here, the curve A shows a QH performance curve when the feed water pump is operated at a frequency f0 (for example, 100% rotation speed, corresponding to the maximum frequency of the inverter). A curve D shows a QH performance curve when the vehicle is operated at a frequency f3 (for example, the minimum rotation speed). Similarly, curves B and C are performance curves of the water supply pump QH when operating at frequencies f1 and f2, respectively. The display of the feed water pump QH performance when operating at a frequency other than these is omitted.

  A curve J is a piping resistance curve of valves, piping, and the like generated when water is pumped by the feed water pump 3 and is a target pressure value when controlling the discharge side pressure of the feed water pump 3. H3 is a target pressure at a point where the amount of water is 0 (zero), and is indicated by the intersection of the pipe resistance curve J described above and the feed water pump QH performance curve D when operating at the frequency f3. H0 is the target pressure at the specification point (when the maximum amount of water used Q0 is used), and is the intersection of the piping resistance curve J and the water supply pump QH performance curve A when operating at the frequency f0 (100% rotation speed). Indicated. Similarly, H1 (intersection of resistance curve J and frequency f1 operation water pump performance curve B) and H2 (intersection of resistance curve J and frequency f2 operation water pump performance curve C) are intermediate target pressures.

  In the embodiment of the present invention, the relationship between the target discharge pressure head and the inverter frequency for controlling the discharge pressure head to a predetermined target value in advance without using the pressure detection is changed to the relationship between the target current and the inverter frequency (rotation speed). Correspondingly, the inverter frequency is controlled so that the inverter current at the time of operation becomes the target current value, and the operation of the feed water pressure head is indirectly controlled to the predetermined target pressure head. Next, the correspondence between these will be described.

  In FIG. 2, a curve E is an inverter current characteristic when the feed water pump 3 is operated at a frequency f0 (for example, 100% rotation speed, corresponding to the maximum frequency of the inverter). That is, it is the characteristic of the current flowing from the inverter to the motor. The intersection of the perpendicular line extending from the point of the water quantity Q0 and the curve E is I0, and this intersection I0 is the target current. The vertical line extending upward from the point of water volume Q0 also intersects with the target pressure H0. When the operating water current is equal to the target current I0 at the time of water consumption Q0, the feed water pressure is the predetermined target pressure. It means that the head H0 is satisfied.

  Similarly, a curve F is an inverter current characteristic when the water supply pump 3 is operated at the frequency f1, and an intersection with a perpendicular extending upward from the point of the water amount Q1 is I1, and this intersection I1 is a target current. The feed water pressure head satisfies the target pressure head H1. Further, similarly, the respective target currents I2 (operating at the inverter frequency f2) and the target currents I3 (operating at the inverter frequency f3) of the water amount Q2 and the water amount 0 (zero) can be obtained. These can be obtained by actually operating and measuring the water volume, pressure, current, and frequency to obtain the corresponding relationship. Here, It is the rated current of the inverter INV, and when the maximum value of the operation range of the feed water pump 3 is the maximum water amount Q0, the combined rated capacity is determined in advance so that the motor rated current does not exceed It.

  Here, a straight line or a curve I (calculation formula) is obtained by connecting the points I0, I1, I2, and I3 of the target current plotted with the invar current and the frequency characteristics.

  In the embodiment of the present invention, an arithmetic expression for obtaining a target current is parameterized, and the current frequency is generalized as a variable. By inputting a plurality of parameters, various types of arithmetic expressions can be generated, and any feed pump It can be applied to models.

Next, when a straight line or a curve I is obtained by an arithmetic expression using parameters, it is as follows.
Formula example of linear approximation I00 = ((I0−I3) / (f0−f3)) * (f0−fx) + I3 (1)
Formula example of curve approximation I00 = ((I0−I3) / (f0−f3) ² ) * (f0−fx) ² + I3 (2)
Here, f0, f3, I0, and I3 are parameters having the meanings of the aforementioned symbols, and fx is a variable and indicates the current frequency. This is because the target current changes as the amount of water used changes, but the target current I00 can be obtained by substituting the current frequency into this variable fx.

  In the above formulas (1) and (2), the highest point (the intersection of the Q0 perpendicular and the E line) is the first coordinate, and the lowest point (the intersection of the zero water volume and the H line) is the second coordinate. Is approximated by a straight line connecting two points and a quadratic curve. In this way, a large number of straight lines or curves I (arithmetic expressions) having different inclinations can be obtained by a plurality of parameters. Therefore, since a large number of arithmetic expressions (straight lines or curves) can be obtained with a small number of parameters, it is possible to cope with various types of water supply pump models without re-entering data as in the conventional example, and work efficiency is improved. . This work is often performed at the time of product shipment of the water supply pump or at the site where the product is installed, and efficiency improvement is extremely effective. The curve I may be a broken line as shown in FIG. 2, and fine control is possible in the case of a broken line.

  Next, in FIG. 1 and FIG. 2, when the specification points (Q0, H0) of the feed water pump 3 are changed, or when the slope of the pipe resistance curve J due to valves, pipes, etc. is changed, an application example. Will be described.

  In any case, on the feedwater pump performance curve, the specification point (Q0, H0), the resistance curve passing through it (corresponding to J), and the point where this resistance curve intersects with water volume 0 (zero) will be the closing pressure Q -H performance curve (equivalent to A, D) is drawn, two coordinates indicated by inverter frequency (equivalent to f0, f3) and pressure head (equivalent to H0, H3) satisfying these are obtained, and corresponding to these two coordinates Draw current curves (corresponding to curves E and H) when operating at two frequencies that give feedwater pump performance, and calculate the current value at the intersection of these current curves and the specified point water volume Q0 and water volume 0 (zero). If desired, two desired parameters (current values) can be obtained. The inverter frequency (corresponding to f0 and f3) for obtaining the two coordinates is also a parameter.

  Generally, when changing an arithmetic expression or changing data, it is very troublesome because it is necessary to change a printed circuit board on which a CPU and a memory are mounted, or to rewrite software and data. In the embodiment of the present invention, a large number of different arithmetic expressions can be automatically generated by changing the parameter value by input from the console CONS, so that the usability is improved. The arithmetic expression is automatically generated by the microprocessor CPU by the arithmetic expression generation program stored in the storage unit M by changing the parameter by the input from the console CONS.

  FIG. 3 shows an algorithm until convergence to the target current when the amount of water used changes. The same symbols as those in FIG.

As is clear from FIG. 3, the current curve is monotonically increasing with respect to the load increase (increase in the amount of water used). Therefore, the frequency control algorithm is as follows.
1. If the inverter current before changing the frequency decreases as the amount of water used decreases, the inverter frequency is reduced (decreased). If the inverter current before changing the frequency increases as the amount of water used increases, the inverter frequency is increased (increased). The width of acceleration / deceleration is determined by examining the resolution, that is, how much the pressure head and current change when the frequency is changed.
2. When the frequency stabilizes after the shift command, the target current is obtained by substituting the current frequency into the arithmetic expression. The timing for calculating the target current is a predetermined time necessary for the frequency to stabilize, or immediately after the shift command is executed and reached. In this way, since the target current is not obtained during the shift (while the frequency is changing), the correct target current can be obtained.
3. If the target current and the inverter current are equal, no shift command is issued.

  A dead zone is provided in the target current to ensure the stability of frequency control. The width of the dead zone is set so that the increase / decrease width of the current due to one increase / decrease does not exceed the target current region. In this way, frequency fluctuations do not occur constantly, and the feed water pressure is stabilized.

  For convenience, it is assumed that the amount of water used is Q1, the inverter frequency is f1, the feedwater pump performance curve is B, the inverter operating current is I1, and the operating points are O1 and O10, respectively. Consider a case where the amount of water used is reduced from Q1 to Q1a from this state.

The operating point moves from O1 (pressure head H1) to O1 ′ (pressure head H1a) on the feed water pump performance curve B, and from O10 (current I1) to O10 ′ (current I1a) on the current curve F of the inverter. Move to. Here, with respect to the current, current I1a <current I1, and the inverter frequency is reduced by Δf by the above algorithm 1. Thereafter, after the frequency is stabilized by the algorithm 2, the target current is obtained and updated. The updated target current I1 ′ (see FIG. 3) is as follows based on the equation (1).
I1 ′ = ((I0−I3) / (f0−f3)) * (f0−f1−Δf) + I3
As a result, the feedwater pump performance curve becomes B ′, the inverter current curve becomes F ′ (f1−Δf), and the operating points move to O1 ″ (pressure head is H1b) and O10 ″ (current I1b), respectively. However, since the currents do not coincide with I1b <I1 ′, the current further decelerates by Δf. After the frequency is stabilized, the target current is obtained and updated. If the updated target current is I1 ″ (see FIG. 3), the target current is as follows.
I1 ″ = ((I0−I3) / (f0−f3)) * (f0−f1-2Δf) + I3
As a result, the performance curve of the feed water pump becomes B ″, the inverter current curve becomes F ″, and the operating points move to O1 ″ (pressure head is H1c) and O10 ″ (current I1c), respectively. Here, the current becomes I1c <I1 ″ (target current), which does not yet match. However, as is apparent from FIG. 3, if the target current is obtained by the calculation formula and updated by repeating the above processing, the target current I2 (including the dead band) is obtained at the frequency f2 (see FIG. 2) (see FIG. 3). 2).

  In the above description, an example in which the amount of water used has decreased is shown. However, when the amount of water used increases, the operation reverse to the above is followed, and each time the target current is obtained and updated by an arithmetic expression.

  FIG. 4 shows a parameter table for each type of water supply pump and motor. As described above, this table is prepared by experimenting in advance for each model, determining parameters of frequency and current, and organizing them. As described above, the parameter f0 is a frequency when the feed water pump 3 is rotated at, for example, 100% rotation speed (maximum frequency of the inverter), and I0 is a target current at that time. The parameter f3 is a frequency when the water supply pump 3 is rotated, for example, with a water amount of 0 (zero), and I3 is a target current at that time. It is the rated current of the inverter INV, and when the maximum value of the operation range of the feed water pump 3 is the maximum water amount Q0, the combined rated capacity is determined in advance so that the motor rated current does not exceed It.

  When applied to a specific model, parameters are selected from the table of FIG. 4 and stored in the storage unit shown in FIG. FIG. 5 is a memory map in which I0, I3, f0, f3, It and the like are stored in the EEPROM, and a variable fx and the like are stored in the RAM. Regardless of the model, the feedwater pump performance and current characteristics are similar, and the number of parameters and configuration are the same, so the parameter configuration is input (or changed) with the same hardware configuration of the control system. Can be applied.

  A control procedure is demonstrated according to the driving | operation procedure flowchart of FIG. In FIG. 6, in 500 steps, parameters necessary for obtaining the target current I00 are read from the memory M, and in 501 steps, an arithmetic expression is generated by the CPU using an arithmetic expression generation program in the memory M. In step 502, the current frequency f3 (f3 is set in fDATA) is substituted for the variable fx of the arithmetic expression in order to give the feedwater pump QH performance shown in FIG. 3 as an initial value. As a result, the target current becomes I3.

  In step 503, it is determined whether a command signal is input from the external operation command signal generator S0. If not input, this loop processing is executed until it is input. If it has been input, in step 504, the inverter outputs the frequency f3 and the corresponding voltage to the motor and starts operation. In step 505, standby processing for a predetermined time (here, for example, Δt1) necessary until the output frequency f3 is stabilized is executed. Instead of the waiting time process of 505 steps, it may be a process of confirming whether the commanded frequency has reached f3 in steps 515 to 517 (see FIG. 8).

In step 506 in FIG. 6, the inverter current during operation is detected, and the data (IDATA) is read (see storage unit M103 in FIG. 5). In step 507, the target current I00 (I3 in this example) is read, and in step 508, processing for comparing the target current I00 with the inverter current IDATA in operation is executed. As a result of comparison,
(1) If IDATA> I00 ± α, the process jumps to a speed increasing process of 509 steps.
(2) If IDATA <I00 ± α, jump to the 512-step deceleration process.
If neither (1) nor (2), the shift process is not performed and the process returns to step 506 and the subsequent processes are repeated. Here, α indicates a dead zone (accuracy of the target current).

  In step 509, the speed is increased by Δf, and fDATA (in this example, f3) + Δf is output as the current frequency. In step 510, a waiting time process until the output frequency is stabilized is executed as in step 505. Of course, this may be replaced with the frequency arrival confirmation processing in steps 515 to 517 (FIG. 8) described above. In step 511, the target current update process is executed, the process returns to step 506, the inverter current detection process is executed, and the process proceeds to step 507.

  In step 512, the vehicle decelerates by Δf and outputs fDATA (in this example, f3) −Δf as the current frequency. In step 513, a waiting time process until the output frequency is stabilized is executed as in step 510. In step 514, the target current update process is executed, the process returns to step 506, the inverter current detection process is executed, and the process proceeds to step 507.

  Using the above algorithm, an example of a state at the start of operation will be described with reference to FIG. The amount of water used at the beginning of use is Q4, the inverter frequency is f3, the feed water pump QH performance curve is D, the assumed target pressure is H3, the inverter current curve is H, and the target current is I3.

As the amount of water used increases to Q4, the operating point moves from O4 to O4 ′, and the operating current becomes I3a. In this state, since the operating current I3a> I3 (target current), the speed is increased by Δf. Assuming that the updated target current after the acceleration is I3 ′, I3 ′ can be expressed as follows.
I3 ′ = ((I0−I3) / (f0−f3)) * (f0−f3 + Δf) + I3
As a result, the feedwater pump performance curve becomes D ′, the inverter current curve becomes H ′, and the operating point moves to O4 ″ (pressure head is H3b) and O40 ″ (current I3b). In this state, since the operating current I3b> I3 ′ (target current), it is not yet coincident. However, it is clear from FIG. 7 that if the above processing is repeated, it becomes equal to the target current (including the dead zone).

  If the above processing is continued, the inverter current is detected along with the fluctuation in the amount of water used, the target current is obtained from the current inverter frequency, and if the inverter frequency is controlled to be equal to this, the feed water pressure head is indirectly set to a predetermined value. The target pressure head can be controlled.

  DESCRIPTION OF SYMBOLS 1 ... Suction pipe, 2, 6 ... Gate valve, 3 ... Water supply pump, 4 ... Motor, 5 ... Check valve, 7 ... Discharge piping, 8 ... Pressure gauge, R, S, T ... Power supply, ELB ... Earth leakage breaker , CU ... variable speed drive, CV ... converter, INV ... inverter, INVU ... inverter part, C ... smoothing capacitor, R ... shunt resistor, PWM ... PWM processing part, CT ... current detection means, I / O ... input / output circuit , CPU ... microprocessor, M ... storage unit (memory), CONS ... setting unit (console), S0 ... external operation command signal generation unit, CU ... variable speed drive device, It ... rated current of inverter unit.

Claims (10)

In a variable speed drive device that obtains a target current from the inverter frequency, and controls the inverter frequency so that the inverter current during operation becomes the target current, thereby controlling the motor and the feed pump at a variable speed.
An inverter for variable speed control of the water supply pump;
Current detection means for detecting the inverter current during operation;
A control unit for controlling the frequency of the inverter based on the detected inverter current ;
A setting unit for inputting parameters for generating an arithmetic expression for obtaining a target current;
A storage unit that stores a parameter input from the setting unit and an arithmetic expression generation program that generates an arithmetic expression using the parameter;
The storage unit stores, as parameters, a first current value and an inverter frequency, a second current value and an inverter frequency,
Wherein the control unit includes a first coordinate in the first current value and the first inverter frequency, the second coordinates respectively formed at the second current value and a second inverter frequency, through the two coordinates Generate a formula to calculate the target current from the inverter frequency,
In accordance with the comparison result between the value obtained by adding the dead band to the target current obtained by this arithmetic expression and the inverter current detected by the current detecting means, the following control is repeated and the target current is updated by the arithmetic expression while updating the target current. Control the frequency,
The update timing of the target current is triggered when the inverter frequency reaches the command frequency by the following control, and the width of the dead zone is set so that the current increase / decrease width does not exceed the target current region. A variable speed drive device characterized by being set.
1. If the detection current of the current detection means <target current ± α, the current inverter frequency is decelerated by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
2. If the detected current of the current detecting means> the target current ± α, the current inverter frequency is increased by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
3. No shift except above. The variable speed drive device according to claim 1,
The first inverter frequency forming the first coordinate is a frequency that satisfies the maximum load of the feedwater pump, the first current value is the maximum load current of the feedwater pump when operating at the first inverter frequency, and the second The second inverter frequency forming the coordinates is set to a frequency satisfying the minimum load of the feed water pump, and the second current value is set to the minimum load current of the feed water pump when operating at the second inverter frequency. A variable speed drive device characterized in that a parameter is set by a setting section and stored in the storage section . In the variable speed drive device according to claim 1 or 2 ,
The variable speed drive device characterized in that the control unit changes the update timing of the target current from the previous frequency to the current frequency and that the inverter frequency reaches this timing . In the variable speed drive device according to claim 1 or 2 ,
The variable speed drive apparatus according to claim 1, wherein the control unit is triggered by a time when a predetermined time sufficient for the frequency output from the inverter unit to reach the current frequency has passed . In the variable speed drive device according to any one of claims 1 to 4 ,
The control unit determines a parameter for generating an arithmetic expression for obtaining a target current in advance for each model of the motor and the water supply pump, and when applied to the specific target model, the parameter for the specific target model is determined based on the parameter predetermined for each model. The variable-speed drive device is characterized in that the parameters are selected and written in the storage unit in advance . In the water supply device that obtains the target current from the inverter frequency and controls the inverter frequency so that the inverter current during operation becomes the target current, and the variable speed control of the water supply pump,
A water supply pump,
An inverter for variable speed control of the water supply pump;
Current detection means for detecting the inverter current during operation;
A control unit for controlling the frequency of the inverter based on the detected inverter current;
A setting unit for inputting parameters for generating an arithmetic expression for obtaining a target current;
A storage unit that stores a parameter input from the setting unit and an arithmetic expression generation program that generates an arithmetic expression using the parameter;
The storage unit stores, as parameters, a first current value and an inverter frequency, a second current value and an inverter frequency,
The control unit forms a first coordinate with the first current value and the first inverter frequency, and forms a second coordinate with the second current value and the second inverter frequency. Generate a formula to calculate the target current from the frequency,
In accordance with the comparison result between the value obtained by adding the dead band to the target current obtained by this arithmetic expression and the inverter current detected by the current detecting means, the following control is repeated and the target current is updated by the arithmetic expression while updating the target current. Control the frequency,
The update timing of the target current is triggered when the inverter frequency reaches the command frequency by the following control, and the width of the dead zone is set so that the current increase / decrease width does not exceed the target current region. A water supply device characterized by being set.
1. If the detection current of the current detection means <target current ± α, the current inverter frequency is decelerated by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
2. If the detected current of the current detecting means> the target current ± α, the current inverter frequency is increased by Δf. (Α is dead zone (accuracy of target current), Δf is speed change range)
3. No shift except above. The water supply apparatus according to claim 6,
The first inverter frequency forming the first coordinate is a frequency that satisfies the maximum load of the feedwater pump, the first current value is the maximum load current of the feedwater pump when operating at the first inverter frequency, and the second The second inverter frequency forming the coordinates is set to a frequency satisfying the minimum load of the feed water pump, and the second current value is set to the minimum load current of the feed water pump when operating at the second inverter frequency. A water supply apparatus, wherein parameters are set by a setting unit and stored in the storage unit. In the water supply apparatus of Claim 6 or 7,
The said control part changed the timing which updates a target electric current from the last frequency to the present frequency, and triggered it that it reached | attained this, The water supply apparatus characterized by the above-mentioned. In the water supply apparatus of Claim 6 or 7 ,
The water supply device according to claim 1, wherein the control unit is triggered by a time when a predetermined time sufficient for the frequency output from the inverter unit to reach a current frequency has passed . In the water supply apparatus as described in any one of Claims 6-9 ,
The control unit determines a parameter for generating an arithmetic expression for obtaining a target current in advance for each model of the water supply pump, and when applied to the specific target model, the parameter for the specific target model from the parameter predetermined for each model The water supply apparatus is characterized by selecting and writing in the storage unit in advance .

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