JPS59190494A - Water pump pressure control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a pump control device, and more specifically, a constant speed pump that is directly driven by a commercial power source and a variable speed pump that is driven via an inverter circuit. In a water supply system comprising:
This relates to the a device.

[Prior Art] This type of water supply system includes a side-tilt motor pump system for water and sewerage. In other words, water drawn from a river or a water storage dam is stored in a tank, cleaned and sterilized, and then the pressure is increased to a certain extent by a feed pump, and then the water is supplied to various areas through pipes. In this case, many pumps are installed to increase the water pressure, but depending on the condition of the water receiving side, it may be possible to supply water with fewer pumps than the number of installed pumps, or even use all of the installed pumps to supply water. , the drive of the pump is controlled according to the state of the water receiving side.

In that case, a general-purpose induction motor is used, combining a constant-speed pump that is driven directly by commercial power and a variable-speed pump that is driven via an inverter circuit and whose rotation can be freely changed.
If the water supply pressure from the constant speed pump is insufficient, it is compensated for by driving the variable speed pump.

Figure 1 shows a schematic diagram of a conventional pump control system of this kind, in which the variable speed pump is rotationally controlled by a single inverter circuit 3, and the electric motor has a general purpose motor. . The 2il-1 constant speed pump is equipped with an induction motor for the Ichido Konkeyakeri 7R, and rotates at a constant rate after startup.Only one pump is shown in the diagram, but many can be installed side by side. It is.

4.5 Check valve provided in the discharge side piping 6 of these pumps,
7 and 8 suction pipes on the tank 9 side, 10 a flow rate detector attached to the cooling part of the west pipe 6, 11 a water supply with a branch pipe 12 between the flow rate detection 410 and the pump 1.2. A small detector that detects pressure, a 13idPI controller,
By controlling the switching of the transistors forming the inverter circuit 3 using the output signal, the speed of the variable speed pump 10 is changed. 1/i is a number switching point detector that detects the switching point of the pump by obtaining a detection signal from the flow rate detector 10, and controls the closing of the switch 16 based on the detection signal. This is a switch for starting the 15-speed variable speed pump 1. Also, +7. IFt is a breaker inserted in each pump circuit.

According to the configuration shown in FIG. 1, first, by closing the switch 15, the variable speed pump 1 starts rotating, and water is distributed via the flow rate detector 10. The water pressure at that time can be detected by the pressure detector 11, and on the other hand, it is detected by the flow section detector 10, and the switch 16 is fully closed by the output signal of the detector 14, and the constant speed pump 2 also rotates. And pressure detector 1
If the detected value at 1 does not reach the predetermined value, P controller 1
A signal is output to the inverter circuit 3 through the inverter circuit 6, and the switching circuit of the inverter circuit 6 is controlled to increase the rotational speed of the variable speed pump 1. Thereafter, when the pressure reaches a predetermined value, the inverter circuit 3 is similarly controlled, and the speed of the variable speed pump 1 is lowered by one revolution to keep the pressure constant.

In this way, when controlling the number of variable speed pumps 1 using frequency control and constant speed pumps 2 using commercial power, the pumping H
The relationship between the flow rate Q and the flow rate Q is as shown in FIG. In Figure 2, A is the characteristic when the inverter circuit 3 is used and the variable speed pump 1 is rotated at 100% and when one constant speed pump is driven, and B is the characteristic when the variable speed pump 1 is operated with commercial power. This is the characteristic when driven. This is the characteristic when two pumps are operated in parallel.The horizontal line indicates the pumping position to keep the water pressure constant, and the intersection of each characteristic curve A, B, and O is variable speed pump 1.
This is a so-called switching point that controls zero rotation.

According to this configuration, variable speed pump 1 and constant speed pump 2
If the pressure of Pressure may be applied to the check valve 4 of the variable speed pump 1, and the variable speed pump 1 may no longer discharge, resulting in so-called shut-off operation. Therefore, it is necessary to use a variable speed pump 1 that can obtain an output one rank higher than that of the constant speed pump 2, which has the disadvantage of increasing costs.

[Object of the Invention] The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a pressure control device that does not cause shut-off operation even when a variable speed pump and a constant speed pump with the same output are used. .

``Summary of the Invention'' The present invention focuses on the fact that the electric motor that drives the pump has a time rating against overload, and uses a switching point correction circuit to enable operation at the same frequency as the commercial power supply at the switching point. By providing this, the above objective has been achieved.

"Embodiment of the Invention" An embodiment of the present invention will be described below in detail with reference to FIGS. 6 and 4. FIG. 3 shows a specific circuit configuration thereof, and is the same as FIG. 1. In FIG. 6, a switching point correction circuit 19 is provided between the PI controller 13 and the inverter circuit 6 to correct the number switching point. , this switching point correction circuit 1
Reference numeral 9 performs output control based on a comparison result between the output of the switching point detection circuit 14 and the output of the PI regulator 13, and controls the switching of the inverter circuit 3.

According to the circuit shown in FIG. 6, the variable speed pump 1 is first rotated by closing the start switch 15, and the water sucked up from the tank 9 is distributed via the piping 6, and the discharge pressure at that time is detected. The signal is detected by the controller 11, converted into an electrical signal, and sent to the P controller 16.

The detected discharge pressure value fed back to the P controller 13 is compared with a pressure setting signal preset in the P controller 16, and a deviation signal is sent to the inverter circuit via the switching point correction circuit 19. is output to control the rotational speed of the variable speed pump 10. Here, as shown in FIG. 4, when the flow rate reaches Q, a switching signal is output from the flow rate detector 10, which is input to the number switching point detector 14, from which a setting signal is output. The signal is input to the switching point correction circuit 19 and added to the deviation signal. As a result, the inverter circuit 3 is controlled to increase the speed of the variable speed pump 1id to 100% rotation (controlled at the same frequency as the commercial power supply).

Thereafter, by closing the switch 16 controlled by the output of the detector 14 at a predetermined timing, the constant speed pump 2 is started, and both pumps are operated in parallel.

When the flow rate reaches Q, the signal from the detector 14 disappears, and the variable speed pump 1 is controlled only by the deviation signal. In other words, constant pressure control is achieved by lowering the frequency of the variable speed pump. In this case, at the switching point, the variable speed pump 1 becomes a temporary load, but as the switching is completed within the rated overload time of the motor, the pump motor is not affected in any way.

When the discharge flow rate decreases from Q to QIK, the speed control of one variable speed pump is performed in the same manner. Figure 2 shows its operating characteristics, where A is the characteristic when the variable speed pump 1 is rotationally controlled by an inverter circuit, B is the characteristic when the variable speed pump 1 is driven by a variable speed M source, and Constant speed pump 2
Characteristics and C are characteristics when two pumps are operated in parallel. In this manner, according to the same embodiment, there is no shutoff operation between the variable speed pump 1 and the constant speed pump 2, so both pumps can be used with the same output.

Further, this type of control circuit can be easily applied to applications in which a variable speed pump and a constant speed pump are operated in parallel, such as when a constant pressure is maintained at a constant end pressure, water level control and flow rate control.

[Effects of the Invention] As is clear from the above embodiments, according to the present invention, a variable speed pump whose rotation is controlled via an inverter circuit and a constant speed pump whose rotation is directly controlled by a single commercial cylinder source are the same. Even if a pump with an output of

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional water supply pressure control device that performs pressure control using two types of pumps, Fig. 2 is a characteristic diagram explaining the operating characteristics of Fig. 1, and Fig. 6 is an implementation of the non-invention. give an example'
FIG. 4 is a diagram illustrating the operating characteristics of the water supply pressure control device. 1...variable speed pump, 2. constant speed pump, 3. inverter circuit, 10. flow Information detector, 11... Pressure detector, 13... PI regulator, 11
... Switching point detector, 19... Switching point correction circuit

Claims (1)

[Claims] A constant speed pump driven by a commercial power source and a variable speed pump driven via an inverter circuit are arranged side by side, and a pressure detector W detects the discharge pressure of both pumps and controls the inverter circuit; The water supply system is equipped with a flow rate detector that detects the amount of discharge 7, and when the water supply pressure by the constant speed pump decreases, the inverter circuit is controlled to increase the rotational speed of the variable speed pump to keep the water supply pressure constant. The pump pressure control device compares the detection signal from the pressure detector with a preset pressure setting signal, and adds the water supply pressure obtained from the flow rate detector to the deviation signal obtained by the comparison. A water supply pump characterized in that a switching point correction circuit is provided to control the inverter (path 01) to increase the rotation speed of the variable speed pump when the water supply pressure decreases by adding a switching point timing signal to keep the water supply pressure constant. pressure control device.