JP4502152B2 - Electric pump control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for an electric pump.
[0002]
[Prior art and its problems]
In conventional electric pumps without rotation control, the load fluctuation of the pump increases to the right as the pump discharge increases, so the maximum is not possible for electric pumps used in a wide range from high to low heads. The motor is designed based on the load at the discharge amount, and the motor output is fully utilized only when it is used in the large discharge amount region with a low head. In other regions, the original motor output is used. This is a very useless way of doing only the following work and the motor output is not fully utilized, so this is a factor that increases not only the main body but also the power supply equipment, manufacturing cost In addition, the running cost is forced to increase. In addition, in the conventionally known power value constant control, the current value flowing to the motor also fluctuates as the pump discharge amount changes, so that the motor rated current value can be rotated without exceeding the motor rated current value within a certain range. Although the number control can be performed, the large output amount region with a low head cannot be used due to overcurrent, and the motor output is not fully utilized.
[0003]
OBJECT OF THE INVENTION
An object of the present invention is to provide a control device for an electric pump in which the motor output is always fully utilized in a wide range from a small discharge amount region with a high head to a large discharge amount region with a low head.
[0004]
[Structure of the invention]
In the control device for the electric pump according to the present invention, the rotational speed control unit that receives power from the facility power source and controls the rotational speed of the pump motor to a variable speed based on the output signal from the switching selection unit described later, a sensor part, a microcomputer calculation part, A power detection unit for detecting a power value of a system connected to the pump motor from the equipment power source, a motor current detection unit for detecting a current value flowing in the pump motor comprising a sensor part and a microcomputer calculation unit, the power detection A power setting unit for setting a target power value in a sub- system to an arbitrary value, a motor current setting unit for setting an upper limit value of a motor current allowed in the current detection unit system to an arbitrary value, Power to output a rotation speed decrease command when the detected value is larger than the set target value of power, and output a rotation speed increase command when the detected value is smaller A comparison section, a motor current comparison section that outputs a rotation speed reduction command only when the detected value is larger than the upper limit set value of the motor current, a rotation speed command from the power comparison section and a motor current comparison section When a rotation speed command is input and the detected value is smaller than the upper limit set value of the motor current, the power value is constant, and when the detected value is larger, the current value limit control method is automatically selected. by switching the control mode to the switching selecting portion for outputting said switching signal, the controller of the electric pump ing from these elements.
[0005]
[Action]
Set the power value corresponding to the motor rated value of the electric pump to be used as the power target value in the power setting part of the control device, set the upper limit value of the motor current in the motor current setting part of the control device, and control from the equipment power supply The electric pump is driven by receiving power to the device and supplying power from the control device to the pump motor. The power value of the system connected from the equipment power source to the pump motor is detected by the power detection unit, and the power target value set by the power setting unit is compared with the detection power value by the power comparison unit, and the detected power value is larger than the target value. In this case, a rotation speed reduction command is output, and when the detected power value is smaller, a rotation speed increase command is output . The motor current value is constantly detected by the motor current detection unit and compared with the upper limit set value by the motor current comparison unit. When the detected current value is larger than the upper limit set value, a rotational speed reduction command is output, and the rotational speed command from the power detection unit system and the rotational speed command from the current detection unit system are input to the switching selection unit, When the detected value is smaller than the upper limit set value of the motor current, the control method is automatically switched to the constant power value method and when the detected value is larger, the current value limit control method is selected. It is.
[0006]
【Example】
Hereinafter, description will be made with reference to the drawings of the embodiments.
[0007]
In FIG. 1, 1 is an equipment power source, 2 is a control device, 3 is a rotation speed control unit included in the control device 2, and the rotation speed of the pump motor 4 is variable based on an output signal from the switching selection unit 7 described later. To control. 5 is an electric pump composed of the pump motor 4 and the pump unit 6, 8A is a power setting unit included in the control device 2 for setting a target power value to an arbitrary value, and 8B is an upper limit of the motor current. The motor current setting unit included in the control device 2 for setting the value to an arbitrary value , 9A is a power detection unit for detecting the power value of the system connected from the equipment power source 1 to the pump motor 4, and the sensor portion It consists of a microcomputer operation part. Reference numeral 9B denotes a motor current detection unit for detecting the current value flowing through the pump motor 4. The motor current detection unit 9B includes a detection sensor portion and a microcomputer calculation unit. For example, the current value flowing through the pump motor 4 is detected by detecting the current value of the DC portion. Calculate by The power detection unit 9A and the motor current detection unit 9B may be provided in the control device 2 or may be provided externally. 8A is a power setting unit in the system of the power detection unit 9A, and sets a target power value to an arbitrary value by, for example, an operation from an external interface. A motor current setting unit 8B in the system of the motor current detection unit 9B is included in the control device 2 and sets an upper limit value of the motor current allowed by an operation from an external interface to an arbitrary value. 10A is a power comparison unit included in the control device 2 for comparing the set target value of power and the detected power value. When the detected power value is larger, a rotation speed reduction command is output, and the detected power When the value is smaller, a rotation speed increase command is output. 10B outputs a rotation speed reduction command only when the detected current value is larger. The switching selection unit 7 is included in the control device 2 in order to switch to the power value constant control or the current value limit control by selecting the rotation number command from the power comparison unit 10A and the rotation number command from the motor current comparison unit 10B. When the detected value is smaller than the upper limit set value of the motor current, the rotation speed of the pump motor 4 is adjusted so that the power value becomes constant, and a frequency power source corresponding to the adjustment is supplied from the rotation speed control unit 3 to the pump motor 4. When the electric pump 5 is controlled by the constant power value control method to be supplied to the motor and the detected value becomes larger than the upper limit set value, the electric pump 5 is controlled by the current limit control method for limiting the motor current value. That is, according to the load state of the electric pump 5 , the power value constant control method is automatically switched to the current limit control method or the current limit control method to the power value constant control method. The power target value in the power setting unit 8A and the upper limit set value of the motor current in the motor current setting unit 8B are appropriate for the motor rated value of the electric pump 5 to be used. It is desirable to have the value set.
[0008]
If the rotation control of the electric pump is performed by the device of the present invention, the operation characteristics as shown in FIG. 3 are obtained. TH1, P1, and I1 indicated by broken lines in the figure are characteristics when operating at a constant speed, and TH2, P2, and I2 indicated by solid lines in the figure are operating characteristics when the apparatus of the present invention is used. Q indicates the discharge amount, TH indicates the total lift, P indicates the power, and I indicates the motor current. P1 and I1 indicated by broken lines when operating at a constant speed are low in the small discharge amount region and have a characteristic of rising to the right as the discharge amount increases. Accordingly, TH1 indicated by a broken line in the small discharge amount region is also lowered. Further, the detected current value reaches the upper limit current value according to the load condition of the electric pump, and the detected current value is divided by the point a on the TH2 characteristic line, the point b on the I2 characteristic line, and the point c on the P2 characteristic line. In the small discharge amount region on the left side where the current is small, the rotational speed control is performed so that the target power value P2 of the constant power value control method is constant up to the point c , and the large discharge amount region on the right side where the detected current value is larger. When the detected current value at the point b reaches the upper limit current value, the control method is automatically set so as to be the current limit control method in which the rotation speed is controlled to be constant at the upper limit current value so as not to exceed the upper limit current value. By switching , the respective characteristics become TH2, P2, and I2 indicated by solid lines, and a higher head in the small discharge amount region and an overload prevention in the large discharge amount region are realized.
[0009]
【The invention's effect】
According to the control device for the electric pump of the present invention, either the constant power value control method or the motor current value limit control method is selected and automatically switched according to the load condition of the pump to increase the head in the small discharge amount range. In addition, it is possible to realize overload prevention in a large discharge amount region with a low head, and there is an effect that burnout of the pump motor can be prevented. In addition, since the motor output is always fully utilized in a wide range of areas, it is possible to cope with the relatively high pump requirement specification point with a smaller pump than the conventional pump. There is an advantage that the manufacturing cost as well as the running cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration in an embodiment of an apparatus of the present invention.
FIG. 2 is a flowchart showing a control mode of an electric pump by the device of the present invention.
FIG. 3 is a diagram showing operating characteristics of an electric pump according to the device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Equipment power supply 3 Speed control part 4 Pump motor 7 Switching selection part 8A Electric power setting part 8B Motor current setting part 9A Electric power detection part 9B Motor electric current detection part 10A Electric power comparison part 10B Motor electric current comparison part

Claims (1)

This system consists of a rotation speed control unit that receives power from the equipment power supply and controls the rotation speed of the pump motor to a variable speed based on an output signal from the switching selection section described later. power detector for detecting a power value, the motor current detector for detecting a current flowing through the pump motor consists of a sensor portion and a microcomputer computation unit, any power values to target in the power detector system A power setting unit for setting a value, a motor current setting unit for setting an upper limit value of a motor current allowed in the current detection unit system to an arbitrary value, and a detection value compared with a set target value of the power A power comparison unit for outputting a rotation speed reduction command when the detected value is smaller and a rotation speed increase command when the detected value is smaller, and a ratio with the upper limit set value of the motor current. And motor current comparison unit for outputting a rotational speed reducing instruction only when the larger detection value, the rotational speed command from the speed command and the motor current comparing portion from the power comparison section is input, the upper limit of the motor current When the detected value is smaller than the set value, the power value is constant, and when the detected value is larger, the control method is automatically switched to output the switching signal so that the current value limiting control method is obtained. A switching selection unit for the electric pump, characterized by comprising these elements.

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