Patent Application
20150039103
This application claims the benefit and priority of Chinese Application No. 201310335773.0, filed on Aug. 2, 2013, the entire disclosure of which is incorporated herein by reference.
The present disclosure relates to the field of industrial automatic control, and in particular to a control device and a control system for a converter.
This section provides background information relating to the present disclosure, which is not necessarily a prior art.
As high-voltage variable-frequency speed regulating devices advance and upgrade, control systems employing closed-loop control of the high-voltage converters continue to improve in their performance. In the field of industrial control, e.g., in a constant-pressure water supply or air supply system, often the user requires a better closed-loop control capacity of the high-voltage variable-frequency speed regulating system, in order to achieve automatic control and regulation. Accordingly, the requirement of the closed-loop control performance of the high-voltage variable-frequency speed regulating device has been raised.
A touchscreen is a new programmable control terminal, which can provide a human-machine interface. Touchscreens can be used in on-site control; they are highly reliable, easy to program, and convenient to use and maintain. Using a touchscreen where technical parameters are many and human-machine interaction is needed can significantly enhance the function of automatic control of the entire production.
PLC (Programmable Logic Controller) has the features including high calculation speed, extensive instructions, powerful function, high reliability, easy to use, flexible programming and good anti-interference capability. With the continuous progress of science and technology, all industries are imposing a higher requirement on the degree of automation; and using modern automatic control techniques plays an important role in reducing labor intensity, optimizing production process, increasing productivity and lowering production cost.
Therefore, it is desirable to provide a control device and a control system for a converter that incorporate both the touchscreen and PLC, which can achieve a better closed-loop control capability and thus meet user requirements.
This section provides a general summary of the present disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
An object of the present disclosure is to provide a control device and a control system for a converter that incorporate both a touchscreen and PLC, can achieve a good closed-loop control capability, and thus meet user requirements.
According to an aspect of the present disclosure, there is provided a control device for a converter, including: a touchscreen adapted to provide a human-machine interface; a communication adapter plate connected to the touchscreen, the touchscreen communicating with the communication adapter plate using a first communication protocol; and a PLC control device adapted to control the converter, the PLC control device being connected to the communication adapter plate and communicating with the communication adapter plate using a second communication protocol that is different from the first communication protocol.
According to another aspect of the present disclosure, there is provided a control system, including: a control device according to the present disclosure; a converter controlled by the control device; an actuating mechanism controlled by the converter to actuate control of a controlled object; and a sensor adapted to sense the controlled object and transmit a resulting sensing signal to a PLC control device in the control device.
In the control device and the control system for a converter according to the present disclosure, the touchscreen and the PLC control device using different communication protocols are connected by the communication adapter plate. Thus, even if commercially available touchscreen products and PLC products use different communication protocols, they can be connected to achieve a good closed-loop control capability and thus meet user requirements.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. In the drawings:
While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. Note that corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The technology of variable-frequency speed regulation herein refers to a technology of stepless speed regulation for an AC motor, which has been widely used in speed control fields such as constant-pressure water supply and constant-pressure air supply due to its unique and excellent control performance. In water supply industry, for example, due to the special needs of production safety and water quality, constant pressure of water supply is strictly required, which leads to intensive application of the technology of variable-frequency speed regulation.
In supplying water by a pumping station, the technology of variable-frequency speed regulation can be used to maintain a constant water pressure. The control system can be switched between manual and automated operations; and automated switching between the multiple pumps is supported. The system has sleep and wake-up functions. When external use of water stops, the system is put into a sleep state and then will be automatically waked up once there is a water use request. The system can adjust PID parameters online, and has such functions as pump set and line protection, alert, and signal display.
While the pumping station is at work, the actual pressure in the pipe network will be feedback and compared with a given pressure. When the pressure in the pipe network is insufficient, the converter increases its output frequency, which speeds up the pump, increases water supply and causes the pressure in the pipe network to increase. On the other hand, if the pressure in the pipe network is too high, the speed of the pump can be slowed down, the water supply will decrease, and the pressure in the pipe network will drop, thereby achieving constant-pressure water supply.
As shown in
The control device 110 may further include a touchscreen 111 and a PLC control device 112.
The touchscreen 111 may provide a human-machine interface, so as to display in real time operating status of the device and the system. In addition, the touchscreen 11 may transmit an instruction or data to the PLC control device 112 through touch, and then control the system or device through the PLC control device 112. The touchscreen 111 may include multiple monitoring views so as to substitute conventional electrical operating panels as well as display and recording instruments, and may have more powerful functions.
The PLC control device 112 is the core of the control system. The PLC control device 112 may acquire various data of the system and make conversion between analog signals and digital signals, and may perform calculation for logic control and PID regulation of the whole system. In addition, the PLC control device 112 may provide the touchscreen 111 with the acquired data and processed data, and may execute various instructions initiated by the touchscreen 111. Furthermore, the PLC control device 112 may convert the resulting data of PID calculations into an analog signal as a control signal regulating the output frequency of the converter 120.
The converter 120 is controlled by the PLC control device 112. Specifically, some internal parameters of the converter 120 may be set by the touchscreen 111 through the PLC control device 112, and the converter 120 may adjust the speed of a water pump or a fan according to data (analog signal) from the PLC control device 112.
The motor 130 which is an actuating mechanism is controlled by the converter 120, to actuate control of the controlled object 140 such as a water pump or a fan.
The sensor 150 may sense the controlled object 140, and may transmit a resulting sensing signal to the PLC control device 112.
Specifically, the sensor 150 may be a pressure (or flow) sensor, and convert the sensing result into a current signal ranging from 4 to 20 mA, which is fed to the PLC control device 112. The PLC control device 112 may compare a given value set by the touchscreen 111 with the actual value acquired by the PLC control device 112. That is, according to a set voltage (or flow) value corresponding to a constant-voltage (or constant-flow) state and the fed-back current signal acquired from the pressure (or flow) sensor 150, the PLC control device 112 may automatically regulate and change the frequency output of the converter 120 based on PID control.
In other words, using the touchscreen and PLC in a closed-loop control variable-frequency system allows the operator to directly set in the touchscreen a target value (pressure, temperature, etc.), which is used by the PLC to be compared with an actual value (measured by the sensor), so that a calculated instruction (analog signal) is sent directly to the variable-frequency system, thereby regulating the output frequency of the converter. The converter controls the controlled object through the motor. The PLC may monitor in real time the magnitude of a parameter of the controlled object as well as a plurality of parameters in the converter, to realize such functions as alerts and recording.
However, currently commercially-available touchscreen products and PLC products are generally equipped with their own communication protocol interfaces. The communication protocol used by a touchscreen product (first communication protocol) being different from the communication protocol used by a PLC product (second communication protocol) limits the user's choice.
In order to allow the user to make a choice flexibly from touchscreen products and PLC products according to his/her needs without the limitation caused by the communication protocols, the inventors of the present disclosure modifies the control system 100 shown in
In the control system 200 according to the embodiment of the present disclosure, the control device 210 differs from the control device 110 shown in
The control device 210 may include a touchscreen 211, a communication adapter plate 213, and a PLC control device 212.
The touchscreen 211 may be used to provide a human-machine interface, which corresponds to the touchscreen 111 shown in
The communications adapter plate 213 is connected to the touchscreen 211. The touchscreen 211 communicates with the communication adapter plate 213 using a first communication protocol. In this embodiment, the first communication protocol may be MODBUS, but is not limited thereto.
The PLC control device 212 may be used to control the converter 120. The PLC control device 212 is connected to the communication adapter plate 213, and communicates with the communication adapter plate 213 using a second communication protocol that is different from the first communication protocol. In this embodiment, the second communication protocol may be PPI (Point to Point Interface), but is not limited thereto.
Thus, the user has the flexibility to choose a touchscreen 211 using a first communication protocol such as MODBUS and a PLC control device 212 using a second communication protocol such as PPI, incorporate them to achieve a good closed-loop control capability, and thus meet user requirements.
Due to the presence of the separate communication adapter plate 213, which has the function to make conversion between different communication protocols, this solution can isolate the protocol conversion function from the other functions, simplifying the design and function implementation.
The MODBUS interface 2131 may, using MODBUS (first communication protocol), receive a signal from the touchscreen 211 or transmit a signal (first signal) to the touchscreen 211.
The PPI interface 2132 may, using PPI (second communication protocol), receive a signal from the PLC control device 212 or transmit a signal (second signal) to the PLC control device 212.
The conversion unit 2133 may convert the first signal into the second signal or convert the second signal into the first signal.
Specifically, the touchscreen 211 equipped with an interface for MODBUS may transmit a signal to the MODBUS interface 2131, and then the MODBUS interface 2131 may transmit the received signal to the conversion unit 2133. Upon receipt of the signal in MODBUS format from the MODBUS interface 2131, the conversion unit 2133 converts the signal into a signal in PPI format, and then transmits the resulting converted signal to the PPI interface 2132. Upon receipt of the signal in PPI format from the conversion unit 2133, the PPI interface 2132 transmits the signal to the PLC control device 212 equipped with an interface for PPI. This realizes the transmission of a signal from the touchscreen 211 to the PLC control device 212.
Correspondingly, the PLC control device 212 equipped with the interface for PPI may transmit a signal to the PPI interface 2132, and then the PPI interface 2132 may transmit the received signal to the conversion unit 2133. Upon receipt of the signal in PPI format from the PPI interface 2132, the conversion unit 2133 converts the signal into a signal in MODBUS format, and then transmits the resulting converted signal to the MODBUS interface 2131. Upon receipt of the signal in MODBUS format from the conversion unit 2133, the MODBUS interface 2131 transmits the signal to the touchscreen 211 equipped with the interface for MODBUS. This realizes the transmission of a signal from the PLC control device 212 to the touchscreen 211.
As can be seen from the above, the communication adapter plate can connect and convert communications in numerous protocols, so that signal communication is realized between the touchscreen and the PLC control device. Processing the protocols separately would require increased hardware and cost. In the embodiment of the present disclosure, the communication adapter plate processes the protocols integrally, which saves the hardware and cost.
Furthermore, the inventers of the present disclosure found that, the control function of the PLC control device can be divided into external signal processing and internal core processing when the PLC control device is used to control a converter. In the control system 100 shown in
In practice, the number, type and sensing signals of those sensors may change according to different application scenarios. In order to comply with the different external signals, the PLC control device has to be modified to meet different user requirements.
However, the inventers of the present disclosure found that, the modification to the PLC control device normally relates only to the external signal processing, while it is seldom for the internal core processing of the PLC control device to be substantially changed. Therefore, dividing the PLC control device in the hardware aspect according to the external signal processing and internal core processing would simplify the modification to the PLC control device and lower the cost.
The control device 310 may include a touchscreen 311, a communication adapter plate 313, and a PLC control device 312.
The touchscreen 311 may be used to provide a human-machine interface, which corresponds to the touchscreen 211 shown in
The communications adapter plate 313 is connected to the touchscreen 311. The touchscreen 311 communicates with the communication adapter plate 313 using a first communication protocol. In this embodiment, the first communication protocol may be MODBUS, but is not limited thereto.
The PLC control device 312 may be used to control the converter 120. The PLC control device 312 is connected to the communication adapter plate 313, and communicates with the communication adapter plate 313 using a second communication protocol that is different from the first communication protocol. In this embodiment, the second communication protocol may be PPI, but is not limited thereto.
The PLC control device 312 may include a PLC unit 3121 and a control box 3122. The PLC unit 3121 may be connected to the communication adapter plate 313, communicate with the communication adapter plate 313 using the second communication protocol (PPI), and perform external control on the converter 120. The control Box 3122 may be connected to the communication adapter plate 313 and perform internal control on the converter 120.
The PLC unit 3121 may receive a sensing signal from an external sensor 150. The PLC unit 3121 processes the external signal. The control box 3122 performs core calculation. The external signal is processed by the PLC unit 3121, and then is transmitted by communication to the control box 3122 for internal core processing, in order to achieve precise control of the converter 120. The control box 3122 is not equipped with many interfaces, and therefore the PLC unit is required to connect and process the external signal and then transmit the result by communication.
The control box is the core for the converter, and most important data are calculated and processed therein so that the converter can operate. Important programming, hardware (circuit board) developing, and stability and precision calculation can be performed in the control box.
The MODBUS interface 3131 may, using MODBUS (first communication protocol), receive a signal from the touchscreen 111 or transmit a signal (first signal) to the touchscreen 311.
The PPI interface 3132 may, using PPI (second communication protocol), receive a signal from the PLC unit 3121 or transmit a signal (second signal) to the PLC unit 3121.
The conversion unit 3133 may convert the first signal into the second signal or convert the second signal into the first signal.
The optical fiber interface 3134 may selectively transmit the conversion result by the conversion unit 3133 to the control box 3122.
Specifically, the touchscreen 311 equipped with an interface for MODBUS may transmit a signal to the MODBUS interface 3131, and then the MODBUS interface 3131 may transmit the received signal to the conversion unit 3133. Upon receipt of the signal in MODBUS format from the MODBUS interface 3131, the conversion unit 3133 converts the signal into a signal in PPI format, and then transmit the resulting converted signal to the PPI interface 3132. Upon receipt of the signal in PPI format from the conversion unit 3133, the PPI interface 3132 transmits the signal to the PLC unit 312 equipped with an interface for PPI. This realizes the transmission of a signal from the touchscreen 311 to the PLC unit 3121.
Correspondingly, the PLC unit 3121 equipped with the interface for PPI may transmit a signal to the PPI interface 3132, and then the PPI interface 3132 may transmit the received signal to the conversion unit 3133. Upon receipt of the signal in PPI format from the PPI interface 3132, the conversion unit 3133 converts the signal into a signal in MODBUS format, and then transmit the resulting converted signal to the MODBUS interface 3131. Upon receipt of the signal in MODBUS format from the conversion unit 3133, the MODBUS interface 3131 transmits the signal to the touchscreen 311 equipped with the interface for MODBUS. This realizes the transmission of a signal from the PLC unit 3121 to the touchscreen 311.
On the other hand, the PLC unit 3121 may receive a sensing signal from an external sensor 150, and perform external signal processing on the received sensing signal. Based on the results of external signal processing, the PLC unit 3121 may perform external control on the converter 120. The external control can be considered as preliminary control of the converter 120.
Further, the PLC unit 3121 may transmit the result of external processing to the control box 3122. Specifically, according to control related requirements, the PLC unit 3121 may transmit the signal to the PPI interface 3132 in the communication adapter plate 313. The PPI interface 3132 may transmit the received signal to the conversion unit 3133. Then, the conversion unit 3133 may further transmit the signal to the optical fiber interface 3134, and the optical fiber interface 3134 may transmit the signal to the control box 3122 via an optical fiber. The benefits of using optical fiber include fast communication speed, and a large amount of high-speed signals in a short time, which prevents signal delay. As a matter of course, other communication manners may be used according to the user's requirements, and the present disclosure is not limited thereto.
Furthermore, the touchscreen 311 may transmit a user instruction to the control box 3122. Specifically, according to the user's requirements, the touchscreen 311 may transmit a signal to the MODBUS interface 3131 in the communication adapter plate 313. The MODBUS interface 3131 may transmit the received signal to the conversion unit 3133. Then, the conversion unit 3133 may transmit the signal to the optical fiber interface 3134, and the optical fiber interface 3134 may transmit the signal to the control box 3122 via an optical fiber.
Upon receipt of the signal from the touchscreen 311 and/or the PLC unit 3121, the control box 3122 may perform core calculation, so as to achieve internal control of the converter 120. The internal control can be considered as precise control of the converter 120.
The closed-loop system of the high-voltage variable-frequency speed-regulating device according to the present disclosure is achieved based on the PLC unit, control views on the touchscreen, and core calculation by the control box which results in a more stable and reliable closed-loop function. In addition, filtering in the acquisition process of the closed-loop system can reduce false operations of the device caused by disturbing signals. Software parameter setting can realize flexible control of the closed-loop function.
The practical applications in constant-pressure water supply or air supply systems illustrate that, based on the external PLC unit and touchscreen and the internal control box as well as PLC related software programming, perfect closed-loop control of the high-voltage variable-frequency speed-regulating device can be achieved, thereby enabling the high-voltage variable-frequency speed-regulating device to be developed rapidly in an excellent direction.
The converter according to the embodiments of the present disclosure may be a high-voltage converter, but the present disclosure is not limited thereto.
The control system according to the embodiments of the present disclosure may be a constant-pressure water supply system or a constant-pressure air supply system, but the present disclosure is not limited thereto.
The embodiments of the present disclosure is described in detail in conjunction with the accompanying drawings; however, it shall be understood that the embodiments herein is for illustrative purposes only and shall not limit the scope of the present disclosure. For those skilled in the art, various modifications and alternations can be made to the above embodiments without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure shall defined by the appended claims and the equivalent thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201310335773.0 | Aug 2013 | CN | national |
