JPS63105384A - Temperature control method of cooler - Google Patents

Abstract

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

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for controlling the temperature of a fluid to be cooled in a cooler, such as an air fin cooler or a cooling tower, and particularly relates to a method for controlling the temperature of a fluid to be cooled in a cooler, such as an air fin cooler, or a cooling tower. The present invention relates to a temperature control method for a cooler, which adjusts the temperature of a fluid to be cooled by connecting a frequency power source and a power source via a frequency converter in parallel to adjust the rotational speed and number of rotationally operating units of the blower.

[Prior Art] A method of controlling the rotational speed and number of operating motors for cooling water tower blowers to reduce power consumption of the motors and thereby save energy has been widely used. One of these methods is to connect an aS that drives the air blowers installed in the cooling tower and a power source via a frequency converter in parallel to the electric motor that drives each of the air blowers, and detect the load conditions of the cooling tower. By selecting and switching the power source, each blower is selected to rotate at 100%, stop, or rotate at 50%, thereby controlling the water temperature, reducing the theoretical power to one-eighth, and saving energy. It has been proposed (for example, JP-A-55-143398 and JP-A-59-157495).

[Problems to be Solved by the Invention] In the method of adjusting the rotational speed and number of rotating operating units of a blower by connecting the constant frequency power source and the power source via a frequency converter in parallel, for example, when starting the blower Since a starting current flows, if the frequency converting device is started using a power source via the frequency converting device, a large load is placed on the frequency converting device, and a frequency converting device with a large capacity is required for this starting current. In addition, in this method, if you immediately switch from a constant frequency power source to a power source via a frequency converter, or conversely, from a power source via a frequency converter to a constant frequency power source, a power generation effect will occur in the motor, and excess current will be transferred to the motor. As a result, the rotation of the electric motor, that is, the rotation of the blower, becomes unstable, and in severe cases, the electric motor may be damaged. These problems are
This problem is particularly noticeable in air fin coolers, which are susceptible to the effects of outside air temperature, rainfall, etc., as there are many fluctuations in the operating status of the blower.

The present invention solves this problem, and an object of the present invention is to be able to use an inexpensive frequency conversion device with a smaller capacity, and to avoid excessive current flowing to the motor.
The purpose of this invention is to propose a temperature control method for a cooler that can stably rotate a blower and, in particular, stably control the temperature.

[Means for Solving the Problems] The present invention, as a means for solving the above problems, connects a constant frequency power source and a power source via a frequency converter to a plurality of blowers in parallel, and In a temperature control method for a cooler that adjusts the temperature of a fluid to be cooled by adjusting the number of revolutions and the number of rotationally operating units, each blower is started with a constant frequency power source, and the power source is connected to the constant frequency power source and a frequency converter. This is a temperature control method for a cooler that involves turning off one power supply and turning on the other power supply after the rotational speed of the blower has decreased.

[Function] The present invention uses a constant frequency power source to start the blower, so when starting the blower, the starting current is
There is no flow to the frequency converter, so a frequency converter with a small capacity is sufficient.

Furthermore, in the present invention, when switching between a low-frequency power source and a power source via a frequency converter, the power to the blower is temporarily turned off for a predetermined period of time, so that no excessive current flows due to the power generation effect, and the blower is The rotational speed does not become unstable, and the air can be blown stably and the temperature can be controlled with high precision.

[Example] Hereinafter, an embodiment in which the present invention is applied to an air fin cooler will be specifically described based on the drawings.

In FIG. 1, reference numeral 1 denotes an air fin cooler, which has a tube portion 2 through which a fluid to be cooled flows and whose outer surface is covered with fins, and a blower 3 consisting of an electric motor and a fan. . Further, at the outlet of the air fin cooler, a temperature regulator 4 is provided that detects the temperature and transmits the difference between the detected temperature and the set temperature, and further determines the drive pattern of the blower 3 based on the signal from the regulator 4. A temperature controller 5 is provided. Furthermore, a constant frequency power supply switch 6 for driving each blower at full speed, a frequency conversion device 7 for converting the frequency of 60150 cycles to 30/25 cycles and halving the number of rotations of the blower, and a power supply for the frequency converted current. The switch 8 is wired in parallel.

Furthermore, a power supply control device 9 is provided for controlling the on/off state of the constant frequency power supply switch 6 and the frequency-converted current power supply switch 8.

It is preferable that the temperature controller 5 and the power supply control device 9 be integrated into a microcomputer or the like because control can be simplified and the device can be made more compact. In the temperature controller 5, based on the signal from the temperature controller 4, which blowers are to be rotated at full speed and which blowers are to be rotated at half speed.
That is, the drive pattern of the blower is determined. In this case, the drive of each blower 3 is set to give priority to half-speed rotation, and if even if all the blowers are rotated at half-speed, the air volume is still insufficient, some of them are sequentially turned to full-speed rotation. It is also desirable to have the ability to create patterns that change in order to save energy.

Based on the above decision, the power supply control device 9 transmits an activation signal for the power switch 6.8, and
In addition, if the blower 3 is not running in the power supply control device 9 and needs to be started, first turn on the constant frequency power switch 6 to drive the blower 3. It has a function to set the appropriate driving state after the Furthermore, when changing the driving state, a function is provided to turn off the power and then turn on the other power after a predetermined period of time has elapsed. That is, when changing from full speed rotation to half speed rotation, turn off the constant frequency power switch 6,
When the rotational speed of the blower 3 decreases, preferably to half-speed rotational speed, a switch 8 for powering the frequency conversion current is turned on. In this case, switch 6 is turned off and switch 8 is turned off.
Since the timing for turning on varies depending on the characteristics of the electric motor, it is best to determine an appropriate time based on calculations and actual measurements and manage it with a timer. Generally, it is about 1 to 40 seconds, and can be determined as appropriate based on actual measurements. Similarly, when changing from half-speed rotation to full-speed rotation, turn off the switch 8 for the power source of the frequency conversion current, reduce the rotation speed of the blower 3, and preferably, with the electric motor's power generation action completely eliminated, and then Turn on the frequency power switch 6. It is also a good idea to set a time for this and manage it with a timer in the same way as above.

The operating mode of the temperature control device having the above configuration will be described below.

When the temperature of the fluid to be cooled in the air fin cooler increases due to an increase in the outside temperature, the temperature controller 4 sends a negative signal corresponding to the difference from the set temperature to the temperature controller 5.

Based on the negative signal, the temperature controller 5 turns on the blower 3.
The increase in the amount of drive is determined, the drive status is checked,
If there is a blower 3 that is stopped, a signal is sent to the power supply control device 9 to rotate the blower 3 at half speed.

Next, in this power supply control device 9, first.

After starting by transmitting a signal to turn on the constant frequency power switch 6 of the corresponding blower 3, a signal is issued to turn off the switch 6, and after a predetermined time has elapsed, the switch 8 for the frequency converted current power source of the corresponding blower 3 is turned on. put in. If all the blowers 3 are already running at half speed, a signal is sent from the temperature controller 5 to the power supply control device 9 to change the - half speed blower 3 to full speed rotation.

In this power supply control device 9, first, the corresponding blower 3
Turn off the switch 8 for the frequency converted current power supply, and after a predetermined time elapse, turn off the constant frequency power supply switch 6 for the corresponding blower 3.
It sends out a signal to drive it. This operation is repeated until the difference between the temperature of the fluid to be cooled and the set temperature becomes a certain value or less.

On the other hand, if the temperature of the fluid to be cooled in the air fin cooler drops due to a drop in outside temperature or rain.

A positive signal corresponding to the difference from the set temperature is transmitted from the temperature regulator 4 to the temperature controller 5. Based on this signal, the temperature controller 5 decides to reduce the drive amount of the blower 3, checks the driving status, and if there is a blower 3 rotating at full speed, the power supply control device 9 instructs the blower 3 to rotate at half speed.
In this power supply control device 9, the primary output signal is
First, a signal is issued to turn off the constant frequency power supply switch 6 of the corresponding blower 3, and after a predetermined period of time, the switch 8 for the frequency converted current power supply of the corresponding blower 3 is turned on. In addition, if all the blowers 3 are already running at half speed, -
Temperature controller 5 sends a signal to stop blower 3 rotating at half speed.
from there to the power supply control device 9. Then, in this power supply control device 9, a stop signal is transmitted to stop the blower 3. This operation is repeated until the difference between the temperature of the fluid to be cooled and the set temperature becomes a certain value or less.

As described above, the temperature of the fluid to be cooled in the cooler is controlled.

[Effects of the Invention] The present invention as described above is a temperature control device for a cooler in which a constant frequency power source and a power source via a frequency converter are connected in parallel, and each blower is started by the constant frequency power source. Therefore, it is possible to use an inexpensive frequency converter with a small capacity, and when switching between a constant frequency power source and a power source via the frequency converter, it is possible to turn off one power source and reduce the rotation speed of the blower. Because I turned on the other one later,
This provides an exceptional effect in that the blower can be rotated stably without excessive current flowing through the electric motor, and temperature control can also be stably performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment in which the present invention is applied to an air fin cooler. 1... Air fin cooler, 3... Blower, 5... Temperature controller, 6... Constant frequency power supply switch, 7...・Frequency conversion device. 8...Switch for frequency conversion current power supply, 9
...Power control device

Claims (1)

[Claims] A temperature control method for a cooler that adjusts the temperature of a fluid to be cooled by connecting a constant frequency power source and a power source via a frequency converter in parallel to a plurality of blowers and adjusting the rotational speed and number of rotationally operating units of the blowers. In this case, each of the blowers is started with a constant frequency power source, and when switching between the constant frequency power source and the power source via the frequency converter, turn off one power source and let the rotation speed of the blower decrease, then turn on the other power source. A method for controlling the temperature of a cooler characterized by introducing