阅读说明：本技术 变频器多机同步控制系统及控制方法 (Frequency converter multi-machine synchronous control system and control method ) 是由 邢桢林 李兴鹤 孟庆旭 蔡新波 于 2020-11-11 设计创作，主要内容包括：一种变频器多机同步控制系统,包括一台主变频器和多台从变频器,多台从变频器均具有唯一的ID,主变频器和多台从变频器通过总线通信连接；主变频器用于向多台从变频器发送广播信息和查询信息,广播信息包含控制命令和主变频器的工作状态数据,查询信息包含主变频器对从变频器当前状态的查询命令,查询命令包含查询信息代码和从变频器的ID；各从变频器用于根据接收到的控制命令执行相应的动作,并在查询命令中的从变频器ID与自身的ID相同时向主变频器回复与查询信息代码相对应的信息。本发明还提供了一种变频器多机同步控制方法。本发明的系统结构简单,变频器之间交互信息多且交互速度快。(A frequency converter multi-machine synchronous control system comprises a main frequency converter and a plurality of slave frequency converters, wherein the plurality of slave frequency converters have unique IDs, and the main frequency converter and the plurality of slave frequency converters are in communication connection through a bus; the main frequency converter is used for sending broadcast information and query information to the plurality of slave frequency converters, the broadcast information comprises a control command and working state data of the main frequency converter, the query information comprises a query command of the main frequency converter to the current state of the slave frequency converters, and the query command comprises a query information code and the ID of the slave frequency converters; each slave frequency converter is used for executing corresponding action according to the received control command, and replying information corresponding to the inquiry information code to the master frequency converter when the ID of the slave frequency converter in the inquiry command is the same as the ID of the slave frequency converter. The invention also provides a frequency converter multi-machine synchronous control method. The system of the invention has simple structure, more information interaction between the frequency converters and high interaction speed.)

1. A multi-machine synchronous control system of frequency converters comprises a main frequency converter and a plurality of auxiliary frequency converters, wherein the auxiliary frequency converters are provided with unique IDs, and the main frequency converter and the auxiliary frequency converters are in communication connection through a bus;

and each slave frequency converter is used for executing corresponding action according to the received control command and replying information corresponding to the query information code to the master frequency converter when the ID of the slave frequency converter in the query command is the same as the ID of the slave frequency converter.

2. The frequency converter multi-machine synchronous control system according to claim 1, wherein the master frequency converter is configured to alternately send broadcast information and query information to the plurality of slave frequency converters.

3. The system for controlling the synchronization of multiple frequency converters and multiple computers according to claim 1, wherein the main frequency converter is used for automatically stopping and quitting operation when a fault occurs, informing each slave frequency converter of the fault state, rejoining the system after recovering to normal and setting the ID of the main frequency converter to be maximum or minimum;

the slave frequency converter with the largest or smallest ID is used for automatically upgrading to a new main frequency converter after receiving the fault notification sent by the main frequency converter; and each slave frequency converter is used for automatically quitting operation when a fault occurs, rejoins the system after the fault is recovered to be normal and keeps the ID unchanged.

4. The frequency converter multi-machine synchronous control system of claim 1, wherein said master frequency converter is adapted to operate in a speed control mode, and each of said slave frequency converters is adapted to selectively operate in a torque control mode or a speed control mode;

when the slave frequency converters run in the torque control mode, the output torque broadcasted by the master frequency converter is used as the output torque of the slave frequency converter;

when each slave frequency converter operates in the speed control mode, the operating frequency f0 of the master frequency converter is subjected to offset and gain processing to obtain f1, f1 is subjected to amplitude limiting processing to obtain f2, the output current of the master frequency converter and the output current of the slave frequency converter are subjected to PI adjustment and amplitude limiting to obtain delta f3, the bus voltage of the master frequency converter and the bus voltage of the slave frequency converter are subjected to PI adjustment and amplitude limiting to obtain delta f4, and f2 plus delta f3 plus delta f4 serves as the final output frequency of the slave frequency converter.

5. The frequency converter multi-machine synchronous control system according to claim 1, wherein the bus is an RS485 bus.

6. A frequency converter multi-machine synchronous control method is applied to a frequency converter multi-machine synchronous control system, the frequency converter multi-machine synchronous control system comprises a main frequency converter and a plurality of slave frequency converters, the slave frequency converters are provided with unique IDs, and the main frequency converter is in communication connection with the slave frequency converters through a bus, and the frequency converter multi-machine synchronous control method is characterized by comprising the following steps:

the main frequency converter sends broadcast information and query information to the plurality of slave frequency converters, the broadcast information comprises a control command and working state data of the main frequency converter, the query information comprises a query command of the main frequency converter to the current state of the slave frequency converters, and the query command comprises a query information code and the ID of the slave frequency converters;

and each slave frequency converter executes corresponding action according to the received control command, and replies information corresponding to the query information code to the master frequency converter when the ID of the slave frequency converter in the query command is the same as the ID of the slave frequency converter.

7. The method as claimed in claim 6, wherein the master transducer alternately sends broadcast information and query information to the plurality of slave transducers.

8. The frequency converter multi-machine synchronization control method according to claim 6 or 7, further comprising the steps of:

when the main frequency converter breaks down, the main frequency converter automatically stops and quits the operation, and the fault state is informed to each slave frequency converter;

the slave frequency converter with the largest or smallest ID is used for automatically upgrading to a new main frequency converter after receiving the fault notification sent by the main frequency converter;

when the main frequency converter recovers to be normal, the main frequency converter rejoins the system and sets the ID of the main frequency converter to be maximum or minimum;

when the slave frequency converter fails, the failed slave frequency converter automatically quits the operation, and the main frequency converter keeps the ID number of the failed slave frequency converter;

and when the slave frequency converter is recovered to be normal, the slave frequency converter rejoins the system and keeps the ID unchanged.

9. The frequency converter multi-machine synchronization control method according to claim 6 or 7, further comprising the steps of:

when the main frequency converter runs in a speed control mode and the plurality of slave frequency converters all run in a torque control mode, the main frequency converter sends output torque to the plurality of slave frequency converters through broadcasting, and each slave frequency converter takes the output torque broadcasted by the main frequency converter as the output torque of the local machine;

when the main frequency converter operates in a speed control mode and the plurality of slave frequency converters operate in a speed control mode, the main frequency converter sends the operating frequency f0, the output current and the bus voltage of the main frequency converter to the plurality of slave frequency converters through broadcasting, each slave frequency converter performs offset and gain processing on the operating frequency f0 of the main frequency converter to obtain f1, performs amplitude limiting processing on f1 to obtain f2, performs PI regulation and amplitude limiting on the output current of the main frequency converter and the output current of the local machine to obtain delta f3, performs PI regulation and amplitude limiting on the bus voltage of the main frequency converter and the bus voltage of the local machine to obtain delta f4, and takes f2 plus delta 3 plus delta f4 as the final output frequency of the local machine.

Technical Field

The invention relates to a frequency converter multi-machine control technology.

Background

At present, the frequency converter is widely applied to industries such as electric power, heating ventilation, rubber, cement and the like, and the driving equipment comprises a fan, a water pump, a compressor, an internal mixer and the like. With the development of power electronic technology and the improvement of requirements on energy conservation and emission reduction, the high-voltage high-power frequency converter can be more and more widely applied. However, due to the requirements of site limitation, old equipment modification or equipment redundancy, multiple motors are inevitably used to drive one equipment at the same time in some occasions, such as long-distance belt transportation, multiple motor-driven internal mixers, multiple motor-driven ball mills, and the like. This requires that a plurality of frequency converters are matched with each other to perform synchronous control when driving the motor. The synchronous driving of the frequency converter on the market at present has the following problems:

1. the frequency converters are connected through analog quantity, IO and the like, mutual information is less, and signals are easily interfered;

2. the system connection is too complex, and an intermediate control module or a forwarding module is often required to be added between frequency converters;

3. the system has poor fault tolerance, and the whole system is shut down when one frequency converter fails, so that production is reduced and even production is stopped;

4. the function is simple, and the production operating mode that can deal with is less.

Disclosure of Invention

The invention aims to solve the technical problem of providing a frequency converter multi-machine synchronous control system with more interactive information and high interactive speed.

Another technical problem to be solved by the present invention is to provide a frequency converter multi-machine synchronous control system with strong system fault tolerance, which does not affect the continuous operation of the system after any frequency converter fails, thereby improving the reliability of the system.

The invention aims to solve the technical problem of providing a frequency converter multi-machine synchronous control system which comprises a plurality of control modes and can adapt to different production working conditions.

The invention provides a multi-machine synchronous control method for a frequency converter.

The embodiment of the invention provides a frequency converter multi-machine synchronous control system which comprises a main frequency converter and a plurality of auxiliary frequency converters, wherein the auxiliary frequency converters are provided with unique IDs (identities), and the main frequency converter is in communication connection with the auxiliary frequency converters through a bus; each slave frequency converter is used for executing corresponding action according to the received control command, and replying information corresponding to the inquiry information code to the master frequency converter when the ID of the slave frequency converter in the inquiry command is the same as the ID of the slave frequency converter.

The embodiment of the invention also provides a frequency converter multi-machine synchronous control method which is applied to a frequency converter multi-machine synchronous control system, the frequency converter multi-machine synchronous control system comprises a main frequency converter and a plurality of slave frequency converters, the plurality of slave frequency converters have unique ID, and the main frequency converter and the plurality of slave frequency converters are in communication connection through a bus, and the frequency converter multi-machine synchronous control method is characterized by comprising the following steps: the method comprises the steps that a main frequency converter sends broadcast information and query information to a plurality of slave frequency converters, the broadcast information comprises a control command and working state data of the main frequency converter, the query information comprises a query command of the main frequency converter to the current state of the slave frequency converters, and the query command comprises query information codes and IDs of the slave frequency converters; and each slave frequency converter executes corresponding action according to the received control command, and replies information corresponding to the query information code to the master frequency converter when the ID of the slave frequency converter in the query command is the same as the ID of the slave frequency converter.

The invention has at least the following advantages and characteristics:

1. in the frequency converter multi-machine synchronous control system, the main frequency converter and the multiple auxiliary frequency converters are in communication connection through the bus, an intermediate module or a forwarding module does not need to be added, an additional control module does not need to be added, system control is completed through a frequency converter program, cost can be saved, and the system structure can be simplified. In addition, the control software of the main frequency converters is the same as that of the slave frequency converters, the control commands, the states of the frequency converters, the output current, the bus voltage, the operating frequency and other information are exchanged between the main frequency converters and the slave frequency converters through broadcast information and query information, and the frequency converters exchange more information and have high interaction speed;

2. when the main frequency converter or the slave frequency converter breaks down, the frequency converter multi-machine synchronous control system can enable the broken-down frequency converter to automatically quit operation, and rejoins the broken-down frequency converter into the system after the failure is recovered, so that the stability and the continuity of production are ensured;

3. the frequency converter multi-machine synchronous control of the embodiment provides two control modes simultaneously, the control modes can be freely selected according to different working conditions, and the control effect can be optimized through parameter adjustment, so that the frequency converter multi-machine synchronous control method is suitable for different production working condition requirements, and the production efficiency is improved.

Drawings

Fig. 1 shows a schematic diagram of a frequency converter multi-machine synchronous control system according to an embodiment of the invention.

Fig. 2 shows a control schematic diagram of the slave frequency converter when operating in the speed control mode according to an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

Fig. 1 shows a schematic diagram of a frequency converter multi-machine synchronous control system according to an embodiment of the invention. As shown in fig. 1, the frequency converter multi-machine synchronous control system according to the embodiment of the present invention includes a master frequency converter and a plurality of slave frequency converters, each of the plurality of slave frequency converters has a unique ID, and the master frequency converter and the plurality of slave frequency converters are connected through RS485 bus communication.

The ID of the master transducer and the ID of the slave transducer may be manually set in advance when the system is set up. The control programs of the master frequency converter and the slave frequency converter are consistent, and the master frequency converter or the slave frequency converter can be manually set through parameters. In other embodiments, the master frequency converter and the plurality of slave frequency converters may be communicatively coupled via other industrial buses.

The main frequency converter is used for sending broadcast information and query information to the plurality of slave frequency converters, the broadcast information comprises a control command and working state data of the main frequency converter, the query information comprises a query command of the main frequency converter to the current state of the slave frequency converters, and the query command comprises a query information code and the ID of the slave frequency converters. Each slave frequency converter is used for executing corresponding action according to the received control command, and replying information corresponding to the inquiry information code to the master frequency converter when the ID of the slave frequency converter in the inquiry command is the same as the ID of the slave frequency converter.

In this embodiment, the data protocol for communication is a custom protocol. The master transducer operates in a master mode and the slave transducer operates in a slave mode. Communication can only be initiated actively by the primary transducer in the primary mode. The master transducer alternately transmits broadcast information and query information to the slave transducer. The alternative meaning means that the main frequency converter firstly sends broadcast information, then sends query information, then sends broadcast information, and so on. The broadcast information has short period, high speed and high real-time performance, and can realize information synchronization between a master frequency converter and a slave frequency converter within 10 ms; the query information contains a large amount of data, so that the master frequency converter can know the comprehensive operation information of each slave frequency converter. The control command comprises commands of running or stopping, scram, resetting and the like of the main frequency converter, and the working state data of the main frequency converter comprises information of output current, unit bus voltage, output torque, running frequency, faults and the like of the main frequency converter. All the slave frequency converters receive the broadcast information and do not reply any message to the master frequency converter, and each slave frequency converter executes corresponding action according to the content of the control command after receiving the control command. The inquiry information is composed of a plurality of bytes, wherein the first byte represents the slave transducer ID, the second byte represents the inquiry information code, for example, 01 represents the inquiry total information, 02 represents the inquiry current and voltage, 03 represents the inquiry fault information and the like, and the third and fourth bytes represent the verification information. All the slave frequency converters receive the inquiry command, but only the slave frequency converters with the same ID as the ID contained in the inquiry command reply the state to the master frequency converter, and the slave frequency converters feed back the state to the master frequency converter according to the inquiry information code, wherein the state comprises the information of the ID, the output current, the running frequency, the unit bus voltage, the fault state and the like of the slave frequency converters. The content replied from the frequency converter is composed of N bytes, wherein the first byte represents the ID of the frequency converter, the second byte represents the inquiry information code, the 3 rd to the N-2 th bytes represent the information corresponding to the inquiry information code, and the N-1 th and the N-th bytes represent the check information.

Further, the main frequency converter is used for automatically stopping and quitting operation when a fault occurs, informing each slave frequency converter of the fault state, adding the slave frequency converters into the system again after the fault state is recovered to be normal, and setting the ID of the slave frequency converters to be maximum or minimum; the method comprises the following steps that in a plurality of slave frequency converters, the slave frequency converter with the largest or smallest ID is used for automatically upgrading to a new main frequency converter after receiving a fault notification sent by the main frequency converter; and each slave frequency converter is used for automatically quitting operation when a fault occurs, rejoins the system after the fault is recovered to be normal and keeps the ID unchanged.

The frequency converter multi-machine synchronous control system comprises two control modes, and can select parameters before the frequency converter runs.

Control method 1: the master inverter operates in a speed control mode and all slave inverters operate in a torque control mode. The main frequency converter sends the output torque to all the auxiliary frequency converters through broadcast information, and each auxiliary frequency converter outputs the same torque according to the output torque (namely the output torque broadcast by the main frequency converter is used as the output torque of the main frequency converter). The control mode 1 is mostly applied to the occasions that the motors carried by the frequency converter are directly and hard connected through a speed reducer or a coupling, and the rotation difference is not allowed among the motors at the moment, so that the main frequency converter is responsible for controlling the speed, and the slave frequency converter follows the output torque of the host machine in real time.

Control mode 2: the main frequency converter and all the slave frequency converters operate in a speed control mode, and the output frequency of each slave frequency converter is adjusted according to the output current, the bus voltage and the operating frequency of the main frequency converter. Referring to fig. 2, the output frequency of each slave frequency converter is processed as follows: each slave frequency converter carries out bias and gain processing on the operating frequency f0 of the master frequency converter to obtain f1, f1= k1 f0+ k2, wherein k1 and k2 are gain coefficients and bias coefficients respectively; performing amplitude limiting processing on f1 to obtain f2, performing PI adjustment on the output current of the main frequency converter and the output current of the local machine, performing amplitude limiting to obtain delta f3, performing PI adjustment on the bus voltage of the main frequency converter and the bus voltage of the local machine, performing amplitude limiting to obtain delta f4, and taking f2 +/delta f3 +/delta f4 as the final output frequency of the local machine.

The control method 2 is often applied to the occasion that the motors carried by the frequency converters are flexibly connected through the belt, and because the diameters of the belt pulleys of the motors controlled by the frequency converters are different, the output frequency of each secondary frequency converter needs to be adjusted in order to keep the linear speeds of the belt pulleys of the motors consistent. The operation frequency f0 of the main frequency converter is biased and gain-processed to play a role of coarse adjustment, the output current and the bus voltage are PI-adjusted to play a role of fine adjustment, and the output torque of each auxiliary frequency converter can be balanced.

According to another aspect of the embodiments of the present invention, there is also provided a frequency converter multi-machine synchronization control method, which is applied to the frequency converter multi-machine synchronization control system, and includes the following steps:

the method comprises the steps that a main frequency converter sends broadcast information and query information to a plurality of slave frequency converters, the broadcast information comprises a control command and working state data of the main frequency converter, the query information comprises a query command of the main frequency converter to the current state of the slave frequency converters, and the query command comprises query information codes and IDs of the slave frequency converters;

and each slave frequency converter executes corresponding action according to the received control command, and replies information corresponding to the query information code to the master frequency converter when the ID of the slave frequency converter in the query command is the same as the ID of the slave frequency converter.

Further, the frequency converter multi-machine synchronous control method of the embodiment includes the following steps for fault processing of the frequency converter:

when the main frequency converter breaks down, the main frequency converter automatically stops and quits the operation, and the fault state is informed to each slave frequency converter;

in the multiple slave frequency converters, the slave frequency converter with the largest ID (the ID is the smallest in another embodiment) is automatically upgraded to a new master frequency converter after receiving the fault notification sent by the master frequency converter, and the rest slave frequency converters are kept unchanged;

when the main frequency converter recovers to be normal, the main frequency converter rejoins the system and sets the ID of the main frequency converter to be maximum (in another embodiment, the ID is set to be minimum);

when the slave frequency converter fails, the failed slave frequency converter automatically quits the operation, and the main frequency converter keeps the ID number of the failed slave frequency converter;

and when the slave frequency converter is recovered to be normal, the slave frequency converter rejoins the system and keeps the original ID unchanged.

Further, the method for controlling the frequency converter multi-machine synchronization control in the embodiment includes the following steps:

when the main frequency converter runs in a speed control mode and the plurality of slave frequency converters all run in a torque control mode, the main frequency converter sends output torque to the plurality of slave frequency converters through broadcasting, and each slave frequency converter takes the output torque broadcasted by the main frequency converter as the output torque of the local machine;

when the main frequency converter operates in a speed control mode and the plurality of slave frequency converters operate in the speed control mode, the main frequency converter sends the operating frequency f0, the output current and the bus voltage of the main frequency converter to the plurality of slave frequency converters through broadcasting; each slave frequency converter carries out bias and gain processing on the operating frequency f0 of the master frequency converter to obtain f1, f1= k1 f0+ k2, wherein k1 and k2 are gain coefficients and bias coefficients respectively; performing amplitude limiting processing on f1 to obtain f2, performing PI regulation on the output current of the main frequency converter and the output current of the local machine (taking the output current of the main frequency converter as a given value) and performing amplitude limiting to obtain delta f3, performing PI regulation on the bus voltage of the main frequency converter and the bus voltage of the local machine (taking the bus voltage of the main frequency converter as a given value) and performing amplitude limiting to obtain delta f4, and taking f2 plus delta f3 plus delta f4 as the final output frequency of the local machine.

The frequency converter multi-machine synchronous control system of the embodiment of the invention does not need to add an intermediate module or a forwarding module and an additional control module, the system control is completed by a frequency converter program, the control software of the main frequency converter is the same as that of the auxiliary frequency converter, and the main frequency converter and the auxiliary frequency converter can exchange information such as control commands, frequency converter states, output currents, bus voltage, operating frequency and the like. When the main frequency converter or the auxiliary frequency converter breaks down, the system can enable the broken frequency converter to automatically quit operation and rejoin the system after the failure is recovered, and the stability and the continuity of production are ensured. Meanwhile, the system provides two control modes, the control modes can be freely selected according to different working conditions, and the control effect can be optimized through parameter adjustment, so that the system is suitable for different production working conditions.