JPS5941193A - Controller for turbo refrigerator - Google Patents

Abstract

PURPOSE:To enable to operate in high efficiency by controlling the speed of a motor for driving a turbo refrigerator by a variable frequency controller, thereby reducing the starting and stopping numbers. CONSTITUTION:A variable frequency converter 20 is operated by a controller 21, and a motor 6 is started. When an unstable state occurs in a process state signal 18 during the operation after starting, a discriminator/arithmetic controller 23 discriminates and calculates to set the motor 6 to a low speed by the converter 20 without stopping the motor 6, the rotating speed of an impeller 10 is decelerated to lower the compression efficiency, a bypass valve 15 is simultaneously fully opened, thereby preventing the surging, and maintaining the standby state at the low speed until the unstable state is eliminated. When the signal 18 is released from the unstable state, the motor 6 is stably operated at the rated speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a turbo refrigeration motor that is controlled using a variable station mantissa control device.

[The magical backstory of invention]

Conventional centrifugal chillers have a succinct vane that adjusts the amount of evaporative refrigerant flowing into the compressed sardine machine while monitoring the steamer cold water outlet temperature and motor current, and a succinct vane to prevent surging when the sardine pan is closed. A capacity control device that adjusts the opening of the bypass valve is used to keep the chilled water temperature constant. During operation, if the cold water outlet temperature drops or the motor current increases, the motor is temporarily stopped for 1.9 seconds and then restarted.

Figure 1 is a diagram showing the control circuit of such a conventional turbo chiller.
, the speed increaser 2, the evaporator 3, the imitator compressor 4, the bleed air recovery device 5, and the 't4iL motor 6. The refrigerant is evaporated at a low temperature by removing heat from the cold water flowing in the cold water cooling blind 9 in the evaporator 3, and is sucked into the tar compressor 1. The evaporated W medium in the turbo compressor 1 is compressed by the impeller 10, becomes high pressure, and is sent to the condenser 4. There, it is cooled by the cooling water of the punishment water cooling sound 11 and liquefied. 1 is applied to the float valve 12 and the pressure 8 is applied to the demand board.◇In the operation of such a refrigeration cycle, the load following operation of the turbo chiller is carried out by the capacity control device 1.
This is done at 3. This capacity control device 13 inputs the chilled water outlet temperature 16 and the motor current 17, and adjusts the opening degree of the vacuum vane 14 and the bypass valve 15 so that the chilled water outlet temperature 16 is constant if the motor current 17 is below the rated value. Controls the opening and closing of the refrigerant flowing into the turbo compressor (1)
are doing. Also, if the motor current 17 exceeds the rated value,
The capacity control device 13 switches to current priority control), and when the motor current 17 reaches the rated value, the Zakujo vane 14 k
l='l shi, pa However, during operation, there is a situation in which the operation of the centrifugal chiller becomes unstable, although it does not directly affect the machine.Example V: High starvation pressure due to a rise in the temperature of the cooling water, and a shortage of refrigerant. Turbo compression (lowest suction pressure, cold water outlet II)
When the process status signal 18 becomes unstable, such as when the temperature is moderately cooled to A degree, the turbo refrigeration must be stopped. and,
Once the motor is stopped, no starting current can be applied to the motor until the coil temperature of the motor drops, so there is a problem that it takes time to start the motor.

Furthermore, as the number of starts and stops increases, the cold μ″k becomes 'ili,
There is 208 inside the μ casing, and the refrigerant is dissolved in the lubricating oil from above the machine 41 that is cooling the 10,000 machines. There is a problem with getting stuck.

[Purpose of the invention]

The present invention despises the above points, and +iJ variable frequency political control device L1
Control the speed of the motor using
It is an object of the present invention to provide a control device for a centrifugal chiller that can reduce the number of P/H floating 1U and enable operation with commercial efficiency.

[Summary of the invention]

Therefore, the present invention provides a turbo refrigeration device.
- i, iJ variable frequency converter and its town frequency converter y,
The frequency control device ((, L) 5i
1 B lb, dynamic b), by variable speed drive,
In addition to adjusting the output of the turbo refrigerator, when the system becomes unstable, the electric motor is operated at low speed in standby mode without being clamped, thereby reducing the frequency of starting and stopping of the electric motor. It's a Nishida thing.

[Embodiments of the invention]

Figure 2 shows an example of ``Honkoyu'', and 20 is a
A variable frequency converter 21 is a variable frequency converter 1 for variable sideways movement of tζj46. This is a control device that controls the The control device 21 feeds back the output voltage of the Ij1 milk M wave number conversion device 20 and sets the voltage for performing ill control (flj morning 1).
It is composed of a circuit 22 and an operating condition determination/arithmetic control circuit 23 that monitors the process state signal 18 and the cold water outlet temperature 16, outputs a speed command, and simultaneously controls the opening and closing of the bypass valve 15 and the breaker 8. After the breaker 8 is connected to the official, the control device 21 controls the p variable frequency 7R conversion device 20.
When the motor 6 is activated and the electric motor 6 is activated, the refrigeration cycle is started as described above. ttFi! ! After Ib, 0i1
If an unstable state occurs in the process status signal 18 during operation as described above, the discrimination/arithmetic control circuit 23 discriminates and computes the situation, and activates the variable frequency conversion device without stopping the electric motor 6. , 20 rotates the revolving shaft 6 at a low speed, lowers the rotation speed of the impeller 10 and reduces the efficiency of the pressure Ai 6,
At the same time, the bypass valve 15 is fully opened to prevent surging, and the standby state is maintained in continuous operation until the unstable state is resolved. and process status signal 18
When the unstable state is eliminated, the speed of the electric motor 6 is gradually increased to the rated speed by the variable frequency converter 20, and stable operation is continued at this rated speed. In addition, the voltage control circuit 22 of the control nu'll d% tri 21 feeds back the voltage detection No. 16 through the voltage transformer 24 for "voltage jli!" It is used to perform ITm.

〔Effect of the invention〕

As described above, the iL according to the present invention is provided with a rJ pumping frequency control device to control the speed of the electric motor, thereby achieving low engine speed control through low speed operation. Evening to j'J I,
U, also possible and 2, start without unnecessary stop i\
- By reducing the number of IL cycles, it is possible to prevent the refrigerant bath from entering the pool by increasing the temperature of the coil (by reducing the starting current). In this variable frequency conversion device, the compression efficiency can be adjusted by controlling the load following by controlling the speed of the L-tunning bale and the rotation λ of the compressor's in-! It is not necessary to adjust the flow of evaporative refrigerant into the compressor by the opening and closing operation of the suction vane by the capacity control device, and the suction vane can be removed from the main body of the tarp refrigerator. Therefore, the main body mechanism of the centrifugal chiller can also be simplified.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram of a conventional centrifugal chiller, and FIG. 2 is a control circuit diagram of a centrifugal chiller showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Turbo compressor, 2... Speed increaser, 3... Evaporator, 4... Condenser, 5... Bleed air recovery device, 6...
Electric motor, 7...Sequence tljll @device, 8.
... Breaker, 9... Chilled water cooler, 10... Impeller, 11... Cooling water cooling pipe, 12... Float valve,
13... Capacity control device, 14... Suction vane, 15... Pi l? valve, 16...chilled water outlet temperature,
17... Motor current, 18... Process status signal,
20...h] Variable frequency converter, 21... Control device, 22... Voltage control circuit, 23... Operating conditions publication No. 7
Figure 2

Claims (1)

[Claims] It consists of an electric motor that drives the centrifugal refrigerator, a variable frequency converter that drives the motor at variable speed, and a frequency control circuit that controls the output of the variable frequency converter. The electric motor is driven at variable speed through the variable frequency converter to adjust the output fi14 of the centrifugal chiller, and when the system becomes unstable, the front power distribution motor is continuously operated at a low speed on standby through the variable frequency converter. A tarp refrigerator control device that uses this as an Ih image.