KR20160104179A - Control system of compressor and control method thereof - Google Patents

Abstract

According to one embodiment of the present invention, a compressor control system comprises: a main power unit supplying external power; a micom controller connected to the main power unit and controlling driving of an inverter drive; and the inverter drive controlling starting of a motor of a compressor unit by control of the micom controller. Provided is the compressor control system, wherein the inverter drive PID (proportional-integral-derivative) controls a motor of a compressor unit by converting a frequency based on a setting pressure value determined as a default or determined by a user, a setting lower limit pressure value, and a setting upper limit pressure value.

Description

TECHNICAL FIELD [0001] The present invention relates to a compressor control system,

The present invention relates to a compressor control system and a control method thereof, and more particularly, to a compressor control system that uses an inverter control system capable of reducing power by frequency control, .

A compressor is a mechanical device that pressurizes a fluid using a power engine such as a motor, and is widely used as a home and industrial facility. The compressor is provided with a tank for holding the fluid. In order to prevent a safety accident caused by the high-pressure fluid in the tank and supply a stable pressurized fluid, a control means for controlling the pressure in the tank is required.

In particular, a screw type compressor is widely used as a method for generating a large amount of pressurized air as an industrial facility. In such a screw type compressor, the pressure in the tank is adjusted by controlling the motor using the Y-D (Y-delta) starting system. That is, a Y-D control unit is coupled to a conventional screw type compressor.

The Y-D start-up method supplies compressed air to the tank by operating the motor at full load within the start-up period. When the pressure in the tank reaches the set pressure, the motor is operated under no-load, but the suction valve is closed to prevent generation of compressed air. Then, when the pressure in the tank is lowered by using compressed air, the suction valve is opened again to supply the compressed air by operating the motor at full load.

In this way, the Y-D start system keeps the motor in a continuously operating state, which causes a large power loss during no-load operation. Especially in recent years, energy saving of industrial facilities has been emphasized, and efforts have been required to reduce power loss due to motor startup in a conventional large capacity compressor. Further, the continuous operation of the motor is disadvantageous in that it generates heat, friction, and noise, and it is disadvantageous in that it is difficult to provide stable and uniform compressed air.

In order to solve the above problems, a technical object of the present invention is to provide an inverter control method capable of reducing power by frequency control in a large-capacity screw type compressor, and more particularly to a compressor control method capable of performing bypass processing in the event of a trouble, System and a control method thereof.

According to an aspect of the present invention, there is provided a compressor control system including a main power unit for supplying external power, a microcomputer controller connected to the main power unit for controlling drive of the inverter drive, The inverter drive controlling the motor of the compressor section according to the set pressure, the set lower limit pressure, and the set upper limit pressure value determined by default or set by the user, And a PID (proportional-integral-derivative) control is performed by the conversion.

In one embodiment of the present invention, the microcomputer may further include a bypass signal unit for selectively supplying external power to the original controller side separate from the microcomputer controller.

In one embodiment of the present invention, the original control unit may start the motor of the compressor unit in a Y-D (Y-delta) manner.

In an embodiment of the present invention, the compressor unit may include a screw type air compressor.

According to another aspect of the present invention, there is provided a method of controlling a compressor using the above-described compressor control system, the method comprising the steps of: setting a set pressure, a set lower limit pressure, and a set upper limit pressure The method comprising the steps of: receiving a pressure measurement value of a fluid supplied to a compressor or a fluid in the compressor section; receiving a pressure measurement value of a fluid supplied to the compressor section when the pressure measurement value does not reach a set pressure value at an initial startup; And starting the motor of the compressor by lowering the frequency of the motor when the measured pressure value reaches the set pressure value.

In another embodiment of the present invention, in the normal load operation, the motor is started so that the pressure measurement value is between the set upper limit pressure value and the set lower limit pressure value, and when the pressure measurement value reaches the set lower limit pressure, And the motor can be started at the set minimum frequency when the pressure measurement value reaches the set upper limit pressure.

In another embodiment of the present invention, a motor stop signal may be generated when the time at which the pressure measurement value is maintained above the set upper limit pressure is equal to or greater than a predetermined time during starting the motor at the set minimum frequency.

In another embodiment of the present invention, the motor may be restarted if the pressure measurement value is below the set upper limit pressure after the motor is stopped.

According to another embodiment of the present invention, the external power is supplied to the original control unit side separate from the microcomputer controller according to the user's selection, and the original control unit can start the motor of the compressor unit in the YD (Y-delta) have.

In another embodiment of the present invention, the compressor unit may include a screw type air compressor.

The effects of the compressor control system and the control method thereof according to the embodiment of the present invention described above are as follows.

First, according to the present invention, power can be saved by driving a compressor using an inverter control method by frequency conversion, and damage and failure of a mechanical driving part and a circuit part such as a compressor and a motor can be prevented.

In particular, the power saving effect is further enhanced in a screw compressor of a large capacity. In addition, it is possible to stably supply fluids of uniform pressure to industrial facilities and the like.

Second, even in the event of a failure such as a failure occurring in the inverter control unit, the original control unit can drive the compressor by the bypass process, so that the compressor can be continuously used even when the inverter control unit is disabled or in a maintenance state .

Third, by comparing the pressure measured value of the fluid in the compressor or the fluid supplied to the compressor with the pressure set value, the motor is stopped and restarted, if necessary, to prevent damage to the motor and prevent a safety accident.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a schematic diagram of a compressor control system according to an embodiment of the present invention.
2 is an external perspective view of an inverter control unit according to an embodiment of the present invention.
3 is a schematic block diagram of a compressor control system according to FIG.
4 and 5 are flow charts showing a method of controlling a compressor according to an embodiment of the present invention.
6 to 8 are pressure-time diagrams according to a method of controlling a compressor according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

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

1 is a schematic diagram of a compressor control system according to an embodiment of the present invention.

As shown, a compressor control system according to an embodiment of the present invention includes a compressor unit 1 and an inverter control unit 2. [ Generally, the manufacturer of the compressor includes the compressor, the motor, the reservoir tank, various valves and sensors, and the original control 11 for controlling them. Here, the original control unit 11 drives the motor by a control method called Y-D (Y-delta), the details of which will be described later.

The compressor unit 1 includes a compressor unit 10 and an original control unit 11 wherein the compressor unit 10 can include a compressor for producing a compressed fluid and a motor for driving the compressor . The compressor unit 10 may include, for example, an air compressor of a screw type, and the control method according to the present invention can exhibit a greater power saving effect for such a large-capacity compressor.

The inverter control unit 2 is mostly provided by a manufacturer separate from the compressor unit 1. The inverter control unit 20 is different from the original control unit 11 in that the inverter control unit 20 drives the motor by a PID control method, . ≪ / RTI > In other words, it is also possible to separately install the inverter control unit 2 in order to reduce power consumption and to supply a stable and uniform pressure fluid to the previously installed compressor unit 1.

2 is an external perspective view of an inverter control unit according to an embodiment of the present invention.

As shown in the figure, the inverter control unit 2 includes a case 22 having a hexahedron shape made of metal or resin and various components built in the case 22. [ Four corners on the lower end of the case 22 are provided with leg portions 22 provided with wheels for convenience of movement.

A microcomputer control switch 211 and an operation panel 212 are provided on the front surface of the inverter control unit 2. The user can input or confirm various setting values through the switch 211 and the operation panel 212, The current state of the compressor, motor, control unit, etc. is checked and appropriate operation and stop signals are input. For example, the operation mode, the tank pressure and temperature, the inverter frequency, the inverter current, the inverter power, the accumulated power amount, the operation time, and the load operation time can be confirmed through the operation panel 212.

It is also possible to input or confirm a signal through a separate communication unit in addition to the method of inputting or confirming various signals through the switch 211 and the operation panel 212 mounted on the inverter control unit 2 as described above. This will be described later.

On the upper surface of the inverter control unit 2, a lamp 213 which is automatically turned on when the front door is opened is provided. Further, an air inlet 214 and an air outlet 215 are provided on the side of the inverter control unit 2. When the inverter drive 205 is driven by the normal control signal from the inverter signal unit 202, the microcomputer controller 203 and the control signal unit 204 to operate the compressor unit 10, And an air inlet 214 and an air outlet 215 may be provided for operating the cooling fan.

Hereinafter, a configuration of a compressor control system according to an embodiment of the present invention will be described in detail. 3 is a schematic block diagram of a compressor control system according to FIG.

3, the inverter control unit 3 includes a main power unit 201 for supplying external power, a microcomputer controller 203 connected to the main power unit 201 and controlling the drive of the inverter drive 205, And an inverter drive 205 for controlling the motor start-up of the compressor unit 10 under the control of the controller 203.

An inverter signal unit 202 and a control signal unit 204 are provided between the microcomputer controller 203 and the inverter drive 205 and the compressor unit 10. In addition, the microcomputer controller 203 may be provided with an external communication connection unit 207.

The inverter signal section 202, the microcomputer controller 203, the control signal section 204 and the inverter drive 205 described above are units for inverter control of the motor of the compressor section 10 by the PID method, A bypass signal section 206 and a circular control section 11 may be provided between the main power source section 201 and the compressor section 10 as a control line which is selectively driven.

The main power unit 201 is connected to an external power source and supplies drive power to the inverter signal unit 202, the microcomputer controller 203, the control signal unit 204, the bypass signal unit 206, do.

The inverter signal section 202 is provided between the microcomputer controller 202 and the compressor section 10 and the inverter drive 205 and supplies various status signals of the inverter drive 205 and the compressor section 10 to the microcomputer controller 202 .

The microcomputer controller 203 receives an input signal from the microcomputer control switch 211 provided on the front surface of the inverter control unit 2 (see FIG. 2) and controls driving of the inverter drive 205.

The control signal unit 204 is provided between the microcomputer controller 202 and the compressor unit 10 and the inverter drive 205 and outputs a control signal from the microcomputer controller 202 to the inverter drive 205 and the compressor unit 10 side .

The inverter drive 205 controls the motor startup of the compressor unit 10 under the control of the microcomputer controller 203. Specifically, the inverter drive 205 drives the compressor of the compressor section by a frequency conversion in accordance with PID (proportional-integral-differential) according to a set default or a user-set set pressure, a set lower limit pressure, . Here, the set pressure refers to the pressure value of the tank for storing the high-pressure fluid generated by the compressor, and means a proper pressure value of the fluid required by the user. Further, when the high-pressure fluid in the tank is used in various facilities or the like, the high-pressure fluid must be re-supplied by the amount of use, so that the pressure value of the high-pressure fluid in the tank fluctuates. As the variation upper limit value of the high-pressure fluid, a value requested by the user is referred to as a set upper limit pressure, and a value required by the user is set as a lower limit value thereof.

That is, the motor is started so that the measured pressure value of the fluid supplied to the tank or the tank during the normal load operation is between the set upper limit pressure value and the set lower limit pressure value. Details thereof will be described later.

On the other hand, the bypass signal unit 206 selectively supplies external power to the original control unit 11 side, which is separate from the microcomputer controller 203. That is, in a normal control state, the compressor unit 10 is driven to the first control line through the main power unit 201 - the microcomputer 203 - the inverter drive 205, The main power source 206, the bypass signal unit 206 and the second control line through the original control unit 11, manually or automatically, according to the user's selection, . In other words, the bypass signal unit 206 normally interrupts power supply to the original control unit 11, and supplies power to the original control unit 11 in the emergency situation.

The first control line controls the motor of the compressor unit 10 by the PID method, and the second control line controls the motor of the compressor unit 10 in the YD mode, for example, when the first control line is disabled .

The user can input command signals or input or confirm various setting values to the microcomputer controller 203 by the microcomputer control switch 211 and the operation panel 212 provided on the front surface of the inverter control unit 2 (see FIG. 2) . Alternatively, a command signal may be input to the microcomputer controller 203 using an external device, or various setting values may be input and confirmed. For this, an external communication connection unit 207 may be provided in the microcomputer controller 203. External micro control devices such as a notebook computer, a server, a smart phone, and a smart pad or input / output devices may be electrically connected through the external communication connection unit 207, and a wired or wireless interface may be provided for this purpose. Such wired or wireless interfaces include, but are not limited to, a pin-shaped connection terminal, a USB connector, an infrared port, a Bluetooth port, and a wireless LAN port.

Hereinafter, a method of controlling a compressor according to an embodiment of the present invention will be described in detail. 4 and 5 are flow charts illustrating a method of controlling a compressor according to an embodiment of the present invention, and FIGS. 6 to 8 are pressure-time diagrams according to a method of controlling a compressor according to an embodiment of the present invention.

Referring to FIG. 4, when the power is first supplied to enter the operation mode (S11), the operation is ready (S12). In the operation ready state, the compressor, the motor, the tank, various circuits and the like are self-diagnosed. When an abnormality is found as a result of the self-diagnosis, an alarm is generated (S121). If Y-D operation is performed by the original controller 12 according to the user's selection, the operation proceeds to the bypass operation mode (S122).

In the normal case, the process proceeds to the inverter control mode. When the operation signal is inputted in this mode (S13), the soft spare operation is then executed (S14). (S141) by a time value set in advance by default or a time value input by the user (S141), and then, the operation is no-load operation for the stabilization time until the set pressure is reached (S142). By adopting the slow-stop function as described below in addition to the slow-start function, it is possible to prevent mechanical damage due to an immediate start-stop and ensure a sufficient preliminary operation section.

Referring to Fig. 6, the motor is driven while changing the frequency so that the tank pressure reaches the set pressure P1. When the driving frequency reaches the preset maximum frequency, the motor is driven at the set maximum frequency. The PID control method may cause the up and down movement of the set pressure P1 as shown in FIG. 6, but even if such a fluctuation occurs, the pressure value is set between the set lower limit pressure P2 and the set upper limit pressure P3 . On the other hand, when sufficient stabilization time is ensured in the no-load operation, it is possible to control so that the fluctuation hardly occurs.

Next, when the tank pressure reaches the set pressure, normal load operation is started (S15). If the set pressure is changed by the user or other cause during normal load operation, the load operation is proceeded in response to this change (S16). Steps S15 and S16 are continuously performed, and the control mode of this interval is referred to as a first control line or a first control mode M1.

In the first control mode M1, the pressure in the tank or the pressure of the air supplied to the tank is controlled to be the set pressure by the inverter control system in accordance with the required amount of the compressed air, that is, the load amount. In the interval between the set upper limit pressure and the set lower limit pressure As shown in FIG.

Referring to Fig. 7, the motor is started by the PID control by the frequency conversion so that the set pressure is reached at the first time T1 and the set pressure is continuously maintained. If the tank pressure value becomes high for a reason such as a decrease in the load at the second time T2, it is dealt with by lowering the driving frequency. Nevertheless, when the pressure reaches the set upper limit pressure (P3), the motor is started at the set lower frequency and the time during which the pressure measurement value is maintained above the set upper limit pressure (P3) When the time exceeds a predetermined time, a motor stop signal is generated to protect the system. After the motor stops, the motor can be restarted (auto stop & start function) when the pressure measurement value falls below the set upper limit pressure.

On the other hand, referring to Fig. 8, the motor is started by PID control by frequency conversion so that the set pressure is reached at the first time T1 and the set pressure is maintained. If the tank pressure value is lowered due to the increase of the load in the second time T2, the method of increasing the driving frequency is dealt with. Nevertheless, when the pressure reaches the set lower limit pressure (P2), the motor is started at the set maximum frequency.

Next, when the stop signal is input (S17), if the stop signal is a stop signal by the control algorithm for system protection as described above, automatic no-load operation and stop are performed (S18) (auto stop & start function).

If a stop signal is input by the user or a predetermined off time is reached, a soft preliminary stop operation is performed (S18). During the soft preliminary stop operation, the restart operation is prevented (S181), and then the no-load operation is performed during the stabilization time until the tank pressure becomes the atmospheric pressure or the like (S182) (slow stop function). Thereafter, the control is ended (S19).

Next, when the operation mode is entered in the bypass operation mode (refer to FIG. 5), when the operation signal is first inputted (S20), the equipment operation is proceeded (S21) and the normal load operation is performed (S22). Here, the control mode is referred to as a second control line or a second control mode M2.

In the second control mode (M2), the pressure in the tank or the pressure of air supplied to the tank is controlled by the Y-D (delta) control method. In this control method, the motor runs in full load in the start section, and when the pressure in the tank reaches the set pressure, the motor runs in no-load operation. In the no-load operation, the suction valve is closed at an appropriate time to prevent the compressed air from being excessively supplied into the tank. If the pressure in the tank is lowered due to the use of the load, the suction valve is opened again and the motor is operated at full load to supply compressed air.

Thereafter, when a stop signal is inputted (S23), the equipment is stopped (S24), and the control is ended (S25).

From the system point of view, the above-described compressor control method will be described again.

First, the set pressure P1, the set lower limit pressure P2, and the set upper limit pressure P3 determined by default or set by the user are inputted. Next, a pressure measurement value of the fluid in the compressor unit 10 or the fluid supplied to the compressor unit 10 is input.

If the pressure measurement value at initial startup does not reach the set pressure value (P1), the motor of the compressor section can be started at the set maximum frequency. On the other hand, when the measured pressure value reaches the set pressure value P1, the motor of the compressor unit 10 is started by lowering the frequency. In this way, PID control is performed by inverter control in the normal case.

If an emergency such as a failure of the inverter control line occurs, external power is supplied to the original controller 11 separately from the microcomputer controller 203 through the bypass signal unit 206 according to the user's selection. The original control section 11 starts the motor of the compressor section 10 in the Y-D (Y-delta) manner.

In the above-described embodiment, a method of sensing the pressure value in the tank and controlling the motor drive based on the sensed pressure value has been described. However, it is also possible to perform the temperature control of the compressor unit 1 at the same time or separately. For example, when the oil temperature sensor in the compressor unit 1 senses the temperature and the oil temperature rises above the set upper limit value, the fan motor is operated to lower the oil temperature, and when the oil temperature falls below the set lower limit value, Operation and so on.

When the compressor control system or the control method as described above is used, power can be saved by driving the compressor using the inverter control method using the frequency conversion, and damage or failure of the mechanical driving parts and circuits of the compressor, do. In particular, the power saving effect is further enhanced in a screw compressor of a large capacity. In addition, it is possible to stably supply fluids of uniform pressure to industrial facilities and the like.

On the other hand, even in the event of an emergency such as a failure occurring in the inverter control unit, the original control unit can drive the compressor by the bypass process, so that the compressor can be continuously used even when the inverter control unit is disabled or in a maintenance state . In the case of the inverter control method, it takes a long time to perform maintenance if a failure occurs. In this case, it is a disadvantage that the compressor can not be used. However, according to the present invention, do.

In addition, by comparing the pressure measured value of the fluid in the compressor or the fluid supplied to the compressor with the set pressure value, the motor is stopped and restarted, if necessary, to prevent damage to the motor and prevent accidents.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

1: compressor unit 10: compressor unit
11: source control unit 2: inverter control unit
20: inverter control unit 201: main power supply unit
202: inverter signal section 203: microcomputer controller
204: control signal unit 205: inverter drive
206: Bypass signal unit 207: External communication connection

Claims (10)

In a compressor control system,
A main power unit for supplying external power,
A microcomputer controller connected to the main power unit and controlling drive of the inverter drive;
And an inverter drive for controlling the motor start of the compressor section under the control of the microcomputer controller,
Wherein the inverter drive controls the PID (proportional-integral-differential) control of the motor of the compressor section by frequency conversion in accordance with a set pressure, a set lower limit pressure, and a set upper limit pressure value set by default or set by a user. Control system.
The method according to claim 1,
Further comprising a bypass signal unit for selectively supplying external power to the original control unit side separate from the microcomputer controller.
3. The method of claim 2,
Wherein the original control unit starts the motor of the compressor unit in a YD (Y-delta) manner.
The method according to claim 1,
Wherein the compressor section comprises a screw-type air compressor.
A method for controlling a compressor using a compressor control system according to claim 1,
A set lower limit pressure and a set upper limit pressure value that are set by default or set by a user;
Receiving a pressure measurement value of a fluid in the compressor unit or a fluid supplied to the compressor unit;
And starting the motor of the compressor section at the set maximum frequency when the measured pressure value does not reach the set pressure value at the time of the initial start and lowering the frequency when the measured pressure value reaches the preset pressure value to start the motor of the compressor section Wherein the compressor control method comprises the steps of:
6. The method of claim 5,
The motor is started so that the pressure measurement value is between the set upper limit pressure value and the set lower limit pressure value under normal load operation, and when the pressure measurement value reaches the set lower limit pressure, the motor is started at the set maximum frequency, And when the value reaches the set upper limit pressure, the motor is started at the set minimum frequency.
The method according to claim 6,
Wherein the controller generates the motor stop signal when the time during which the pressure measurement value is maintained at the set upper limit pressure or more during the startup of the motor at the set minimum frequency is equal to or longer than a predetermined time.
8. The method of claim 7,
And restarts the motor when the pressure measurement value becomes equal to or lower than the set upper limit pressure after the motor stop.
6. The method of claim 5,
Wherein the external power is supplied to the original control unit separately from the microcomputer according to the user's selection, and the original control unit starts the motor of the compressor unit in the YD (Y-delta) manner.
6. The method of claim 5,
Wherein the compressor unit comprises a screw type air compressor.

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