JP2608399B2 - Pump device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a pump device that detects an idle operation and stops the pump when the pump operated by photovoltaic power generation runs idle due to a decrease in water level or the like. It is.

(Prior art)

2. Description of the Related Art In recent years, pump devices using a solar power generation device have been spotlighted, for example, for irrigation in desert areas. In particular, in such a zone, it is required to be unmanned for the convenience of maintenance and the like, and it is required to operate in an unmanned state for a long time without failure.

In a pump device operated by such a solar power generation device, when the pump runs idle at a high speed due to a decrease in water level, an accident such as burning of the shaft of the pump occurs, or power is generated by a solar cell. There is a problem that wasteful power is wasted. As a countermeasure against this, conventionally, for example,
As shown in JP-A-57-179385, there is a pump control device provided with a water level detecting means such as a water level sensor, and automatically stops the pump when the water level falls below a predetermined value. In addition, when the flow rate from the pump becomes equal to or less than a predetermined amount by a flow rate sensor or the like that detects the flow rate from the pump, the pump is assumed to be idle, and
Some stopped the pump.

[Problems to be solved by the invention]

However, as described above, in a device that detects an idle operation of a pump using a water level sensor or a flow rate sensor, the water level sensor or the flow rate sensor or the like must be installed in a location where water is present, so that the entire device becomes large-scale. In addition, there is a problem that maintenance work and the like of these sensors are accompanied by difficult work, and further, since a complicated idle operation detecting means having a configuration including a water level sensor and a flow rate sensor is separately provided, the entire apparatus becomes expensive. There was also a problem.

The present invention has been made in view of the above points, and an object of the present invention is to provide a pump operated by an existing photovoltaic power generation system with a pump having a simple configuration and no need for extensive maintenance and inspection. It is to provide a pump device provided with.

[Means for solving the problem]

A pump device according to the present invention that solves the above problems is a pump device that converts DC power generated by a solar cell into AC power via an inverter, and operates an AC motor connected to the pump using the AC power. Means for transmitting a frequency command signal to the inverter to control the rotation of the AC motor to maintain the output of the solar cell at the maximum point, and to evacuate the pump based on the frequency command signal to the inverter by the maximum power tracking means. Idle operation detection means for detecting operation, and means for stopping the operation of the AC motor when the idle operation detection means detects that the command frequency from the maximum power tracking means has become equal to or higher than a predetermined value. It is characterized by having.

[Action]

Since the present invention configures the pump device operated by solar power generation as described above, it becomes possible to detect the idle operation of the pump based on the frequency command signal to the inverter by the maximum power tracking unit by the idle operation detection unit, The idle operation of the pump can be detected to stop the operation of the AC motor connected to the pump.

Accordingly, it is possible to prevent the AC motor from being damaged due to overheating due to lightening of the load of the AC motor in a state where there is no water and an increase in the rotation speed. Furthermore, since there is no needless operation of the pump during idling, energy can be effectively used.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a system configuration of a pump device operated by a photovoltaic power generator according to the present invention. In the figure, 1 is a solar cell, 2 is an inverter for converting DC from the solar cell 1 into AC, 3 is a switch for supplying an AC output of the inverter 2 to the induction motor 4, and 5 is driven by the induction motor. Pump. Reference numeral 7 denotes a maximum power tracking unit that performs tracking control so that the output of the solar cell 1 reaches a maximum point, as will be described in detail later. Reference numeral 8 denotes a comparator that outputs when the set frequency of the maximum power tracking unit 7 exceeds a predetermined value. , 9 is a relay operated by the output of the comparator 8, 10 is a setting device for giving a predetermined value to the comparator 8, 9a is a normally closed contact of the relay 9, 3a is an exciting coil of the switch 3, and 3b is a switch of the switch 3. A normally open auxiliary contact 11 is a start switch for starting the induction motor 4 and driving the pump 5.

Here, the comparator 8 and the setter 10 constitute idle operation detection means 12 for detecting the idle operation of the pump 5 based on the frequency command signal to the inverter 2 by the maximum power tracking means 7. The normally closed contact 9a, the switch 3, and the exciting coil 3a are connected to the pump 5 when the idle operation detection means 12 detects that the command frequency from the maximum power tracking means 7 has exceeded a predetermined value. Stop means 13 for stopping the operation of the induction motor 4, which is an AC motor, is also provided.

In the pump device having the above configuration, the start switch 11 is turned on.
Then, an operating current flows through the exciting coil 3a of the switch 3, and the switch 3 is closed. Thus, the DC power generated by the solar cell 1 is converted into AC power of a predetermined frequency by the inverter 2 and supplied to the induction motor 4, whereupon the induction motor 4 is activated and the pump 5 is driven. At this time, the maximum power tracking means 7 controls the frequency of the inverter 2 so that the output of the solar cell 1 becomes the maximum point, and controls the rotation speed of the induction motor 4 as described later in detail. That is, when the sunlight irradiating the solar cell 1 is weak and the amount of power generation is small, the output frequency of the inverter 2 is lowered to rotate the induction motor 4 at a low speed and the pump 5
In contrast, when the amount of sunlight is strong and the amount of power generation is large, the output frequency of the inverter 2 is increased, and the induction motor 4 is rotated at a high speed to increase the load on the pump 5.

Therefore, when the water level of the pump 5 becomes idle, the maximum power tracking means 7 tends to consume a large amount of power generated by the solar cell 1, and the control frequency of the inverter 2 increases because the pump 5 rotates at high speed. If a frequency value at which the pump 5 becomes idle is set in advance by the setter 10, the comparator 8 outputs an output when the control frequency of the maximum power tracking means 7 exceeds the set value, and the relay 9 is turned on. Activate. When the relay 9 operates, its normally closed contact 9a opens, and the exciting coil
The excitation current to 3a is cut off, the switch 3 opens, and the induction motor 4 and the pump 5 stop.

There are various types of the maximum power tracking means 7, for example, those described in Japanese Patent Application Laid-Open No. 56-132174 and Japanese Patent Application No. 56-132174 filed by the present applicant as an inverter using solar cells. No. 167680 (JP-A-58-69469). The details are described in the above-mentioned publications, but the portions related to the present application are cited from JP-A-58-69469.

The second is a block diagram showing a system configuration of the inverter using solar electricity. In the copper diagram, a main inverter 22 is driven by a solar cell 21, and an AC motor as a load 23 is driven by an AC output of the main inverter 22. The auxiliary inverter 24 generates control electric power necessary to operate the main inverter 22. The capacity control circuit 25 detects the output voltage V and the output current I of the solar cell 21, and
The output of the main inverter 22, that is, the frequency and the voltage, are controlled so as to operate at the point Pmax at which the output power of the voltage V-current I characteristic of the solar cell shown in FIG. 3 reaches the maximum output. Reference numeral 26 denotes a current sensor.

When the capacity control circuit 25 is used as the maximum power tracking means 7 in FIG. 1, the solar cell 1 is always operated at the maximum output point Pmax.

The relationship between the total head of the pump 5 and the flow rate is as shown in FIG. 4, and the output of the induction motor 4 and the pump 5
The relationship with the flow rate is as shown in FIG. As is clear from FIG. 4, the present pump device needs to increase the command frequency to the inverter 2 as the total head becomes longer, and as is clear from FIG. The output of the induction motor 4 also increases, and the rotation speed of the pump 5 also increases.

As described above, the load is reduced when the water level is reduced and the pump 5 is in the idling state, so that the load is reduced in order for the maximum power tracking means 7 to maintain the output of the solar cell 1 at the maximum output point Pmax. Therefore, it is necessary to consume an amount of generated power, and a command to increase the output frequency is output to the inverter 2 so that the induction motor 4 and the pump 5 are rotated at a high speed.

Therefore, if the output frequency of the inverter 2 when the pump 5 runs idle is set by the setter 10, the comparator 8 outputs an output when the control frequency of the inverter 2 of the maximum power tracking means 7 reaches a predetermined value. , The relay 9 is activated and the relay 9
The normally closed contact 9a opens to cut off the exciting current of the exciting coil 3a, so that the switch 3 is opened and the induction motor 4 is opened.
Stops. With the configuration as described above, the idle operation of the pump 5 can be prevented only by adding a circuit including the comparator 8 and the relay 9 having a simple structure.

In the above embodiment, a circuit including the comparator 8, the relay 9, and the normally closed contact 9a is used to open and close the switch 3 when the control frequency of the inverter 2 exceeds a predetermined value. However, the present invention is not limited to this. For example, a non-contact relay formed of a transistor or the like may be used. In other words, a switch that detects that the control frequency of the inverter 2 exceeds a predetermined value and opens the switch 3 Should be fine. In addition, a circuit may be provided to stop the inverter 2 based on the output of the comparator 8, and the inverter 2 may be stopped when the control frequency of the inverter 2 exceeds a predetermined value.

〔The invention's effect〕

As described above, according to the pump device of the present invention,
When the control frequency of the inverter of the maximum power tracking means becomes equal to or higher than a predetermined value, the idle operation detection means of the pump determines that the pump is idle and stops the AC motor. Without providing pump idle operation detection means that is difficult to use for maintenance and inspection, it is easy to perform maintenance and inspection, etc., and it is possible to prevent idle operation of the pump with an extremely inexpensive device. An excellent effect is obtained that damage to the AC motor due to overheating due to lightening of the load and increase in the rotation speed can be prevented as much as possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of a pump device operated by a photovoltaic power generator according to the present invention, and FIG. 2 is a block diagram showing a system configuration of a solar cell-based inverter previously filed by the present applicant. FIG. 3 shows the voltage V of the solar cell.
FIG. 4 shows the relationship between the total head of the pump and the flow rate, and FIG. 5 shows the relationship between the output of the induction motor and the flow rate of the pump. DESCRIPTION OF SYMBOLS 1 ... Solar cell, 2 ... Inverter, 3 ... Switch, 4 ... Induction motor, 5 ... Pump, 7 ... Maximum power tracking means, 8 ... Comparator, 9 ... Relay, 10 ... Setting device, 11 ... Start switch

Claims (1)

(57) [Claims] 1. A pump device for converting DC power generated by a solar cell into AC power via an inverter and operating an AC motor connected to a pump with the AC power, wherein a frequency command signal is transmitted to the inverter. And the maximum power tracking means for controlling the rotation of the AC motor to maintain the output of the solar cell at the maximum point, and detecting the idle operation of the pump based on a frequency command signal to the inverter by the maximum power tracking means. And a means for stopping the operation of the AC motor when the idle operation detecting means detects that the command frequency from the maximum power tracking means has become equal to or higher than a predetermined value. A pump device.