JPH0988871A - Rotating machine control device and control method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] A rotary machine control device that allows the inverter itself to operate optimally according to the load condition without omitting the speed command input terminal of the inverter and without providing a complicated peripheral circuit. To provide. [Configuration] When the speed at which the inverter INV operates according to the load state is set in advance from the console CONS, the set data is stored in the memory in the microcomputer MCU and the operating program is also stored. Has been done. The load state of the inverter is detected by the current detecting means CT1 and CT2 and taken into the microcomputer MCU. Further, the inverter is provided with FW and COM terminals as operation command input terminals, and operation is started by inputting signals to these. [Effect] Since the inverter itself determines what kind of pattern to operate according to the load state, the start command terminal F
Full-automatic operation can be performed only by connecting an external operation command means to the W and COM terminals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling an electric motor for driving a rotary machine such as a turbo pump or a turbo blower by an inverter and a control method thereof.

[0002]

2. Description of the Related Art In a rotary machine such as a turbo-type pump or a turbo-type blower, the amount of supplied water and the amount of air are proportional to the operating speed.
The feed water pressure and the wind pressure are proportional to the square of the operating speed, and the output is proportional to the cube of the operating speed. This means that the operating speed may be reduced when the load amount is reduced, which has an advantage that energy can be saved. Therefore, if the rotating machine is driven by an inverter, the rotation speed can be controlled, so that it is possible to easily control the water supply volume, water supply pressure, air volume, wind pressure, etc. according to load fluctuations. It is considered that speed control by inverter will increase.

Then, among these, an example in which a pump of a water supply device is used as a rotary machine and an inverter is used for its operation will be described with reference to FIGS. FIG. 8 shows the configuration of the entire water supply device. This water supply device includes a suction pipe 1, a pump 3, a motor 4, a water supply pipe 6, a pressure tank 7, sluice valves 2-1, 2-2, and a quick-closing reverse type. It comprises a stop valve 5, a pressure sensor 8, a flow sensor 10, a pressure gauge 9, and a controller (not shown) shown in FIG.

FIG. 9 shows the operating characteristics of this water supply system with the pressure H on the vertical axis and the water amount Q on the horizontal axis.
Is a Q-H characteristic curve when the operating speed of the pump is N _A , and curves B and C are Q-H characteristic curves when the operating speed is N _B and N _C , respectively. Here, H ₀ is the maximum water supply flow rate Q _A
When issuing the a minimum pressure required to be able to sufficiently use water at highest faucet (total head), thus, as the pump 3, based on the discharge pressure H ₀ Therefore, a pump having a capacity capable of the flow rate Q _A is required. Although the actual pump operating speed is stepless, these curves A, B, and C show the performance at stepwise speeds for convenience. Pump 3, in FIG. 9, if the amount of water used is changed with Q _A → Q _B → O, Lee (operating speed N _A), b
At each point of (operating speed N _B ) and C (operating speed N _C ), operation is performed while maintaining a constant discharge pressure H ₀ .

FIG. 10 shows the above-mentioned control device, in which PW is a power source, ELB is an earth leakage breaker, and INV is an inverter. CONS is a console and inverter I
These are a setting unit and a display unit for NV control constants (such as acceleration / deceleration time and V / F characteristics). Next, IM is an electric motor for driving the pump, and corresponds to the motor 4 shown in FIG. SS is a start switch, STX is a relay, and CU is a control unit. The control unit CU includes a microprocessor CPU, a memory M, and an input / output port PIO.
-1, PIO-2, PIO-3, stabilized power supply AVR, digital / analog converter D / A, analog / digital converter A / D, and constant setting unit SW.

In the water supply system of FIGS. 8 and 10, first, only the sluice valve 2-2 is closed, the earth leakage breaker ELB is turned on, and the switch SS is closed, so that the main power supplies R, S, T of the inverter INV are closed. Electric power is supplied to the terminals, the contacts of the relay STX are closed, the FW terminal and the COM terminal of the inverter INV are short-circuited, and further power is supplied from the stabilized power supply AVR to the control unit CU to complete the preparation for operation.

Next, if the sluice valve 2-2 is opened from this state, or if water is used on the end-end customer side, the water supply pressure decreases, and this is detected by the pressure sensor 8. The pressure signal detected by the pressure sensor 8 is
Input / output port PIO-2 to CP via converter A / D
It is read into the U register and stored in the memory M.

Then, this pressure is preset in the constant setting unit SW.
If it is lower than the starting pressure set by the CPU and stored in the memory M, the CPU determines, for example, the operating speed N _C shown in FIG.
From the input / output port PIO-1 to the converter D /
It outputs to the speed input terminals O and L of the inverter INV via A. Therefore, the inverter INV is
Three-phase AC power having a predetermined voltage at a predetermined frequency corresponding to the _C signal is output to the motor IM to drive the pump 3. Thus, the pump 3 is operated at the operating speed N _C.

Thereafter, when the amount of water used fluctuates and the water supply pressure fluctuates, the pressure sensor 8 detects this, as described above, and this is preset by the constant setting unit SW and stored in the memory. The discharge target pressure H ₀ is compared by the CPU, and the CPU issues an acceleration / deceleration command to the inverter INV so that they are equal to each other, whereby the water supply pressure is kept constant at H ₀ .

The conventional examples of such an apparatus include Japanese Patent Publication No. 59-54797, Japanese Patent Publication No. 57-113992,
There are various publications of Japanese Examined Patent Publication No. 59-65591.

[0011]

As described above, the use of an inverter for controlling a rotary machine is for controlling pressure and wind pressure and for saving energy. It must be determined by an external command whether the motor must be operated at an appropriate output frequency and output voltage. Therefore, in the related art, as described above, the control device including the control unit CU is used,
The inverter INV is controlled according to the load state.

However, as a result, the conventional technique requires an expensive control device using a microcomputer, and requires an inverter having speed input terminals O and L, which complicates the structure and is expensive. Become. Also,
As a means for detecting the load state, for example, in the water supply device described above, a pressure sensor and a flow rate sensor are used and they are attached to the pipes, but these are expensive, which increases the number of installation work steps and increases the product cost. I am raising. Recently, there is a strong demand for downsizing of such rotary machines and cost reduction of the entire apparatus.

The objects of the present invention are as follows.

1) The inverter speed command input terminals O and L are omitted so that the inverter itself can perform optimum operation according to the load state without providing a complicated peripheral circuit.

2) A peripheral circuit is not required, and a simple circuit configuration is used to achieve small size, light weight, and low cost.

3) Inverter start command terminals FW, CO
Only by connecting an external operation command means to the M terminal, fully automatic operation can be performed.

4) The inverter itself can detect the load state and what kind of pattern the operation is performed.

[0018]

According to the present invention, in a rotary machine control device comprising an inverter, and a variable speed control of an electric motor for driving a rotary machine by the inverter, the relationship between the output current and the output frequency of the inverter is described above. A storage unit that stores the operating characteristics of the rotating machine and a current detection unit that detects the output current of the inverter are provided.
The frequency corresponding to the current value detected by the current detection means is read from the storage means to control the output frequency of the inverter.

Therefore, according to a preferred embodiment, the present invention is as follows. In order to eliminate the need for a speed command from the outside to the inverter,
The speed command algorithm is stored in advance, and the speed command is created based on this.

The speed command algorithm referred to here is
There is a console that sets the inverter speed in advance according to the load status (internal quantity of the inverter), and based on this relationship, there is a console that sets the load status and the inverter speed, and a storage means that stores this set data. There is a means for detecting the load status inside the inverter, and the relationship between the load status stored in the storage means and the inverter speed changes with time as the relationship between the actual load status detected by the detection means and the actual speed. It means to match with.

In the case of the water supply device, what causes the start of operation of the load is a change in pressure or flow rate, which is input to the inverter from the outside, and the inverter operates according to the presence of this signal. If there is no signal, it will stop.

The load characteristic of the rotating machine is represented by a curve in the upper right direction as the load increases, and this is the same even when the rotation speed is changed. Therefore, change the operating load pattern and the inverter load current in advance (corresponding to the change in the inverter internal current).
Is obtained, and this is related to the speed (frequency) of the inverter, and based on this, an algorithm is formed.

[0023]

In place of the relationship between the state quantity outside the inverter and the speed, a storage means for storing the relationship between the state quantity inside the inverter and the speed is provided inside the inverter, and inside the inverter based on the output current of the inverter. A speed command is created. This eliminates the need for a speed command from the outside of the inverter.

Further, in a preferred embodiment, the speed at which the inverter operates according to the load condition is preset from the console. The storage means inside the inverter stores the set data and an operation program. The load state of the inverter is detected by the current detecting means.

Further, the inverter is provided with FW and COM terminals as operation command input terminals, and signals are input to these terminals to start operation based on the above-mentioned set conditions. When driving a rotating machine, the above-mentioned FW,
Input signals from sensors such as pressure and flow rate to the COM input terminal. As a result, the operation according to the load condition of the rotating machine and the predetermined speed can be obtained.

[0026]

The present invention will now be described in detail with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention, which constitutes an inverter device 100 suitable for driving the motor 4 of the water supply device shown in FIG. 8, for example.
R, S and T are AC power supply input terminals, U, V and W are output terminals, and a motor 4 as a load is connected to these output terminals U, V and W. Next, the main circuit of the inverter is a CN that converts electric power from the commercial AC power source into DC.
It is composed of a V (converter circuit) and an INV (inverter circuit) that converts DC power into AC power of an arbitrary voltage at an arbitrary frequency. SH connected to the DC circuit of the main circuit is a shunt for current detection.

Next, RS is a resistor for suppressing inrush current when the power is turned on, CB is a smoothing capacitor, CT1, CT2.
Is a current detecting means for detecting a load current, and has a function of detecting the U- and V-phase currents on the load side and outputting a voltage signal SV ′ representing the output current of the inverter. Note that CT is an abbreviation for a current transformer (current transformer), and a voltage signal SV ′ representing the magnitude of a current detected by the current transformer is converted into digital data by a converter A / D, which will be described later in an MCU. Read by.

The INV is composed of a transistor module, etc., and performs a conversion operation in accordance with a command from an ignition circuit and a current control circuit G, which will be described later, to convert the DC power from the CNV into AC power of a desired voltage at a desired frequency. Convert and motor 4
It works to supply to. The MCU is a microcomputer for monitoring and controlling the inverter device, and is composed of, for example, a one-chip microcomputer. Next, AVR
Is a stabilized power supply for supplying a stable DC control power supply, C
ONS is a console and LCD is a display circuit. Here, the console CONS sets load characteristics, acceleration / deceleration time of the inverter, V / F characteristics (ratio of output voltage and frequency of the inverter). Used to
The LCD functions to display an instruction of input operation, data to be input, output data, or the like.

FW and COM are operation command terminals as described above, and by short-circuiting these terminals, an input composed of a photocoupler FTC, resistors R1 and R2, diodes D1 and D2, a capacitor C1 and the like. A signal is input to the MCU via the circuit.

As is apparent from FIG. 1, first, the MCU
Is load current detecting means CT1, CT2 via A / D.
The voltage signal data representing the output current of the inverter from is read from the signal terminals CN ₀ and CN ₁ . On the other hand, the operation command signal to the MCU is, as described above, the terminals FW and C.
When the photocoupler FTC is turned on by the short circuit between the OMs, the potential level at the lower end of the resistor R2 changes from H to L, which is read from the signal terminal PN5.

Then, the MCU commands the inverter frequency to the ignition circuit via the signal terminal SG1, and further drives the current control circuit G via the signal terminal SG2 to control the inverter output voltage.

Inverter device 1 according to the embodiment of FIG.
When 00 is applied to the water supply device as described above, it becomes as shown in FIG. 2, and the contact PS of the pressure detection means and the contact FS of the flow rate detection means are connected to the FW of the inverter device 100 as the operation command means. Only the connection between the terminal and the COM terminal is required, and the circuit configuration is extremely simple.

The pressure detecting means may be a switch which operates at a predetermined pressure, and its contact PS is a NO contact, that is, a normally open contact, and is closed when the water supply pressure of the water supply device becomes a predetermined value, for example, H ₀ or less. It is a thing. Next, the flow rate detecting means may be a switch that operates at a predetermined flow rate, and its contact point F
S is an NC contact, that is, a normally-closed contact, which opens when the flow rate of water sent from the pump exceeds a predetermined value. As mentioned above, ELB is an earth leakage breaker,
When the ELB is turned on, the water supply device can be operated.

Therefore, in this embodiment, after the ELB is turned on, if the feedwater pressure H ₀ or less is reached, the pump operation is started, and if the feedwater pressure H ₀ is exceeded, it is stopped. When the water supply amount increases abnormally for some reason, the pump operation is immediately stopped.

FIG. 3 is a performance curve diagram of a typical model of a pump device to which the embodiment of the present invention can be applied, in which the voltage value SV representing the output current of the inverter is plotted on the vertical axis. This is shown as showing the load state of the pump. Note that, in this figure, the same reference numerals as those in FIG. 9 are the same, so the description thereof will be omitted.

In FIG. 3, Q1 is the maximum amount of water used in the water supply system by this pump, and is also HT.
Is the required head for flowing this maximum water consumption Q1,
As shown by point a in the figure, the actual lift Ha and the required unend pressure H
p, and the piping loss Hf is included therein. Therefore, it is necessary to select a pump having a QH performance curve A that satisfies the maximum water consumption Q1 and the total head HT under the operating speed N1 (usually the maximum speed).

Next, L1 is a pipe loss curve (load curve) when water is supplied to this water supply system, and shows the load state by the pressure H and the water amount Q. This road curve L1
Can be drawn as follows. First, when the amount of water used Q3 (water amount 0), the piping loss Hf is 0, so the coordinate c is determined, and then, with the amount of water used Q2, the required total head is H1.
Since (Piping loss Hf = H1- (Hp + Ha)), the coordinate B is determined. Therefore, by connecting these coordinates c, b, and a, the load curve L1 is obtained as shown in the figure.

The pump has a water consumption (load) of Q1.
→ When Q2 → Q3 changes, the operating state is on the load curve L1 at point (Q1, H0) → point (Q2, H1) → ha
Move to point (Q3, H2).

By the way, as the load state of the pump changes, the load state of the inverter naturally changes, and the output current changes. Therefore, the actual current detection voltage SV detected by the current detecting means CT1 and CT2 is changed. 'Also changes. Therefore, it is the load curve L2 in FIG. 3 that shows the change in the voltage SV in association with the load curve L1.

This load curve L2 is, as described above,
The voltage SV representing the output current of the inverter is plotted on the vertical axis, and the curve D is the Q-SV when the amount of water used is changed from Q1 to Q2 to Q3 with the operating speed of the pump fixed at N1. Similarly, the curves E and F show curves with the pump operating speeds fixed at N2 and N3, respectively.
It is a Q-SV curve when the amount of water used is changed similarly.

Therefore, the load curve L2 is the coordinate d,
It can be obtained by connecting E and F. At this time, the coordinate A on the road curve L1 corresponds to the coordinate D on the road curve L2, and similarly, the coordinate E for the coordinate B and the coordinate E for the coordinate B The coordinates C correspond to the coordinates C, respectively.

In other words, when the amount of water used is Q1, if the output frequency of the inverter is a value corresponding to the operating speed N1 and the current detection voltage SV 'of the inverter is the target value SV1, the water supply system requires it. This means that the desired pressure HT is satisfied.

Similarly, when the amount of water used is Q2, if the operation speed of the pump by the inverter is N2 and the current detection voltage SV 'of the current detection means is operated to the target value SV2, the water supply system will request. If the desired pressure H1 is satisfied, and the amount of water used Q3, the operating speed N3, and the voltage SV 'of the current detecting means are the target value SV3, the feed water pressure H
2 is satisfied.

Therefore, in order that the relationship between the voltage SV and the operating speed N coincides with the load curve L2, the operating speed N of the inverter, that is, the output, corresponds to the actual current detection voltage SV 'detected by the current detecting means. If you control the frequency,
This means that the operating state of the pump can be controlled along the load curve L1 without inputting the water supply pressure H or the water supply amount Q from the outside of the inverter device 100.

Therefore, in this embodiment, the console CO
Using NS, the relationship between the target current value SV and the operating speed N is set as a function or as a table in advance in the memory in the MCU of the inverter device 100 in accordance with the load curve L2, and the current detection means is used. The operating speed N of the inverter, that is, the output frequency, is controlled so that the actual current detection voltage SV ′ detected in step S1 matches the stored current target value SV. Without inputting the water supply pressure H or the water supply amount Q from the outside, the pump operating condition is the load curve L1.
It is controlled according to.

For example, in FIG. 3, if the actual current detection voltage SV '= target value SV3, the output frequency of the inverter is controlled so that the pump operating speed N = N3 at this time. Similarly, the output frequency of the inverter is controlled so that the operating speed N = N2 when the voltage SV ′ = the target value SV2 and the operating speed N = N2 when the voltage SV ′ = the target value SV3. I will do it.

By the way, these characteristics are performances peculiar to the pump, and differ depending on the individual pump. Therefore, in this embodiment, for each pump, the operating speed N and the detection voltage SV of the load current of the inverter are corresponding to the relationship (piping resistance curve L1) with the desired pressure according to the amount of water used in advance.
The relationship (load curve L2) is calculated in advance, and how to operate the pump based on this load curve L2
It is determined using the console CONS and set and stored in the memory in the MCU of the inverter device 100.

Table 1 shows an example of the setting result at this time.

[0049]

[Table 1]

Table 1 shows an example of data set in advance by the console CONS shown in FIG. 1 for each pump of models A, B, C ... As described above. In addition, in this example, the data is obtained by capturing the water supply amount at three points. However, if more data is arbitrarily selected and stored, finer control can be obtained. It is preferable to prepare the data at points, and the number of points is not limited to three.

Taking the model A as an example, when the flow rate is Q1 and the pressure is H0, the speed NA1 is the speed N1 and the voltage SVA1 is the voltage SV1.
Are stored respectively. Similarly, when the flow rate is Q2 and the pressure is H2, NA2 is for speed N2 and S is for voltage SV2.
When VA2 is stored, flow rate Q3 and pressure H3, speed N
3 is stored in NA3 and voltage SV2 is stored in SV3.

Next, FIG. 4 is an enlarged view of the characteristic diagram shown in FIG. 3 for a representative model for explaining the control algorithm in the embodiment of the present invention. It is assumed that the operating state is the amount of water used Q1, the required pressure H01, the operating speed N1, and the coordinate 1 (Q1, H01) on the load curve L1. At this time, naturally on the load curve L2, the inverter is operating at the operating speed N1 and the load current value voltage SV1 at coordinates 6 (N1, SV1).

Next, in this state, the amount of water used changes from Q1 to Q.
Consider the algorithm when it is reduced to 5. Initial value From FIG. 4, the load current target value at the operating speed N1 is SV.
1. N1 and SV1, N2 and SV2, N3 and SV, so that the load current target value at operating speed N2 is SV2 and the load current target value at operating speed N3 is SV3.
3 are stored in association with each other (a table corresponding to Table 1 is stored). Alternatively, as a function of the load curve L2, SV = f (N) ... (1) is stored in the memory of the above-mentioned MCU.

The amount of water used changes from Q1 to Q5. Since the operating speed is N1, the coordinate 1 on the pump characteristic curve A in FIG. 4 moves to the coordinate 2 and, along with this, the inverter load actual current is the coordinate on the curve D. Coordinate 7 from 6 (N1, SV1)
Move to (N1, SV1 '). Therefore, the inverter load actual current detection voltage SV1 'is detected. The target value SV1 is compared with the detected SV1 ′. Since the result is SV1> SV1 ′, the current speed N is decelerated by ΔN (minimum resolution of speed control, for example, 1 bit). Then, if SV1 = SV1 ′, the current speed N is maintained as it is, while if SV1> SV1 ′, the current speed N is increased by ΔN.

In this state, the operating speed is N4 (N1-Δ
N → N4), the performance curve of the pump moves to A ',
The coordinates move from 2 to 3. Further, the characteristic curve of the operating speed N and the load current voltage SV shifts from D to D ', and the coordinates are 7 (N
From 1, SV1 ') to 8 (N4, SV4').

The target value of the load current at this operating speed N4 is SV = f (N4) ≡SV4 from the above equation (1). Here, in addition, the actual load actual current detection voltage SV
4'is detected.

Comparison of the target voltage SV4 with the detected voltage SV4 ′ Since this result is SV4> SV4 ′, ΔN is further subtracted from the current speed. As a result, the operating speed is N
Since 5 (N4-ΔN → N5), the pump performance curve becomes A ″, and the coordinates move to 4 on the curve A ″, and N-SV
The curve becomes D ", and coordinate 8 (N4, SV4 ') to coordinate 9
Move to (N5, SV5 ').

Then, the target load current at the operating speed N4 is obtained from the equation (1) as SV = f (N5) ≡SV5. Again, the actual load voltage SV
5'is detected.

The target value SV5 is again compared with the detected SV5 ′. The result is SV5> SV5 ′, and a detailed explanation is omitted, but according to the above-mentioned procedure, the speed is reduced by ΔN, and on the pipe resistance curve L1. Coordinate 5 and coordinate 1 on the load load curve L2
Converges to 0.

As a result, the operating speed becomes N6 and the target voltage becomes SV6 (f = (N6)), which matches the detected actual load voltage SV6 '. Therefore, SV6 '= SV6, and in the state of this usage amount Q5, the operation speed becomes stable at N6.

FIG. 5, FIG. 6 and FIG. 7 are flow charts for embodying the above-mentioned algorithm. In the above embodiment, a program based on this is used in advance by the controller 1
00 in the memory of the MCU. First, in FIG. 5, the initial setting of the algorithm described above is executed in step 100. Then, in step 101, an interrupt waiting process is executed.

When an interrupt occurs, the processing shown in FIG. 6 is executed. This interrupt processing is performed by the display circuit L in the control device 100.
This is a display process for a CD, which is executed by, for example, a timer interrupt. First, in step 201, the console C
The ONS mode is confirmed, and in steps 202 to 204 it is determined which display mode is used. Based on the result of this determination, for example, in step 205 the actual load current is displayed, in step 206 the output voltage is displayed, and in step 207.
Then, the frequency is displayed.

If the result of determination in step 202 is that the mode is not the display mode, step 208 is proceeded to, where it is determined whether or not it is the constant setting mode, and if it is the constant setting mode, step 209 is proceeded to, based on Table 1. , The relationship between the operating speed and the load current is set as various data such as N1 = SV1, N3 = SV3, and the function SV = f (N) (equation (1))
Is stored in the memory. At this time, as other constants, data necessary for the operation of the inverter, that is, the minimum speed (minimum frequency), the maximum speed (maximum frequency), V
/ F characteristics, inverter acceleration time (frequency increase speed), deceleration time (frequency decrease speed), etc. are set. Then, when the setting is completed, the flag SET = OFFH is set. When this is completed, the interrupt is restored in step 210, and the process returns to step 101 in FIG.

Next, steps 101 to 102
Then, it is determined whether the flag SET = OFFH or not, and if it is not OFFH, step 101 is looped until the constant setting is completed. Then, during the execution of this loop, the INT1 interrupt processing shown in FIG. 7 is executed.

Now, after an operation command is issued from the outside by an operation such as turning on the ELB shown in FIG.
Assuming that the contact PS of the pressure detecting means and the contact FS of the flow rate detecting means are closed, the starting condition is established,
The terminals FW and COM of the inverter device 100 are short-circuited,
The photocoupler FTC shown in FIG. 1 is turned on, and the terminal PN5 of the MCU becomes "L".

Therefore, in the processing of FIG. 7, step 2
PN5 bit check execution result in 13 proceeds to step 215, where START = O indicating the operable state
Perform FFH. Otherwise, in step 214, S
TART = 00H is executed, the loop is exited in step 216, and the process returns to step 102 in FIG.

Returning to FIG. 5, next, in step 103, START = OFFH is judged. If 00H, step 103 → step 1 until the judgment result becomes OFFH.
01-> step 102-> step 103 is executed. Then, if it becomes OFFH in step 103, it is considered that the starting condition is established here, and the process proceeds to step 104, in which the operation is started at an initial speed, for example N = N5, and the load current target value SV at this time is started. = SV1 is set and stored in the memory.

Next, at step 105, the current detecting means CT
Load current from CT1 and CT2, CT1 and C
Let the averaged detection result of T2 be the actual current voltage SV '. Then, in the next step 106, the target value SV is compared with the value SV ′ just detected, and as a result of the comparison, the next conditional jump is executed.

SV> SV ′ → jump to step 107 SV = SV ′ → jump to step 111 SV <SV ′ → jump to step 109 First, in step 107, according to the algorithm described above, ΔN (minimum from the current driving speed) (Resolution)
The deceleration process for changing to (N-ΔN → N) is executed. On the other hand, in step 108, the load current, which is the next target value, is calculated based on the operating speed after shifting and is updated to a new value, that is, SV = f (N−ΔN) → A process for setting a new load current target value SV is executed, and the process proceeds to the next step 111. Further, in step 109, contrary to the processing in step 107, the speed increasing process (N + ΔN → N) by ΔN is executed,
In the following step 110, the target value is updated by SV = f (N + ΔN) from the operating speed after this acceleration processing, that is, SV = f (N + ΔN) → the new load current target value SV is executed.

In step 111, after waiting time processing for a predetermined time Δt necessary for stabilizing the control system is executed, step 11
In step 2, it is determined whether or not START = 00H. If it is 00H, the stop process is executed in step 113, and then step 102
If it is not 00H, the process returns to step 105 and the subsequent processing is executed. As described above, as described in the algorithm, the operation of converging to the predetermined value can be obtained.

Therefore, according to the embodiment described above,
The following effects can be obtained. Since the speed command input terminal from the outside of the inverter and the circuit necessary for speed command can be omitted, a complicated control circuit in the periphery is not required, and cost reduction, miniaturization and weight reduction can be realized, and great reliability due to circuit simplification. Can be obtained.

The load curve corresponding to the operating load state is determined in advance based on the relationship between the pump and the inverter characteristics, and is directly set and stored in the inverter by the console. The actual load state is detected by the load current detection of the inverter. Since the actual load current detected by the means is controlled so that the detected load actual current and the set load state (load curve) match, optimum operation of the rotating machine becomes possible. As a result of these, fully automatic operation becomes possible with simple operation command means.

When this rotating machine is used as an auxiliary machine for cooling water or the like, the operation is linked with the main machine.
An operation command signal can be received from the main machine, and a sensorless extremely simple device can be obtained.

[0074]

According to the present invention, instead of the relationship between the state quantity outside the inverter and the speed, a storage means for storing the relationship between the state quantity inside the inverter and the speed is provided inside the inverter, and inside the inverter. Since the speed command is created inside the inverter based on the state quantity, this makes the speed command from the outside of the inverter unnecessary.

Therefore, there are the following effects. (1) Even if the speed command input terminal of the inverter is omitted and the complicated peripheral circuit is removed, the inverter itself can perform the optimum operation according to the load condition.

(2) It is possible to reduce the size, weight, and cost with a simple circuit configuration by eliminating the peripheral control circuit.

(3) Full-automatic operation can be performed only by connecting an external operation command means to the start command terminal terminal of the inverter.

(4) It is possible to allow the inverter itself to detect the load state and the pattern of operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram when an embodiment of the present invention is applied to a water supply device.

FIG. 3 is a characteristic curve diagram when the present invention is applied to drive a pump.

FIG. 4 is a characteristic diagram showing a load curve when a pump is operated according to an algorithm according to an embodiment of the present invention.

FIG. 5 is a flowchart showing an algorithm and a driving program according to an embodiment of the present invention.

FIG. 6 is a flowchart showing an algorithm and an operation program according to an embodiment of the present invention.

FIG. 7 is a flowchart showing an algorithm and an operation program according to an embodiment of the present invention.

FIG. 8 is a configuration diagram showing an example of a water supply device using a pump.

FIG. 9 is a characteristic diagram showing an example of operating characteristics of a pump.

FIG. 10 is a configuration diagram showing a conventional example of a rotary machine control device.

[Explanation of symbols]

 1 Suction Pipe 2-1 Gate Valve 2-2 Gate Valve 3 Pump 4 Motor 5 Quick Close Check Valve 6 Water Pipe 7 Pressure Tank 8 Pressure Sensor 9 Pressure Gauge ELB Leakage Breaker INV Inverter AVR Stabilized Power Supply Unit CNV Converter CT1, CT2 Current detection means CPU microprocessor MCU microcomputer CONS console LCD display circuit FTC photocoupler

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Fujii 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Inside the Industrial Machinery Division, Hitachi, Ltd.

Claims (3)

[Claims] 1. A rotary machine control device comprising an inverter, wherein a variable speed control of an electric motor for driving a rotary machine is performed by the inverter, wherein a relationship of an output frequency with respect to an output current of the inverter is matched with an operating characteristic of the rotary machine. A storage unit that stores the current and a current detection unit that detects the output current of the inverter are provided, and the frequency corresponding to the current value detected by the current detection unit is read from the storage unit to control the output frequency of the inverter. A rotary machine control device having the above-mentioned configuration. 2. The rotary machine control device according to claim 1, wherein the rotary machine is a pump of a water supply device, and an operating characteristic of the rotary machine is a discharge pressure characteristic with respect to a flow rate of the pump. . 3. A rotary machine comprising an inverter, wherein an electric motor for driving a rotary machine is controlled at a variable speed by the inverter, wherein an operating speed N of the rotary machine and an output current of the inverter detected by a current detecting means are represented. The step of storing the load load curve obtained from the relationship with the voltage SV, the operating speed N when the rotating machine is operating in an arbitrary state, and the next target value based on the load load curve The step of obtaining the voltage SV representing the output current of the inverter, the voltage SV representing the output current of the inverter, which is the target value, and the voltage SV ′ representing the actual current obtained by the current detecting means are compared, and the operation is performed. The minimum resolution of the speed is ΔN. If SV> SV ', the value of N is N-ΔN, if SV = SV', the value of N is held as it is, if SV <SV ' The step of setting the value of N to N + ΔN, and thereafter updating the voltage SV representing the internal current of the inverter, which is the next target value, based on the operating speed N and the load load curve. A method for controlling a rotary machine control device, comprising: