阅读说明：本技术 一种针对光伏直流升压变换器模块化设计的通信方法 (Communication method for photovoltaic direct-current boost converter modular design ) 是由 魏苗苗 张新雷 王环 王一波 周宇 窦德刚 于 2020-11-20 设计创作，主要内容包括：本发明公开了一种针对光伏直流升压变换器模块化设计的通信方法,集中型光伏直流升压变换器的模块输入并联/输出串联(IPOS)的组合结构,针对IPOS级联方案电路特点,系统采用集散式控制架构,主控单元和模块控制单元之间以光电隔离单元作为统一对外接口,采用光纤高速通讯实现系统及模块间的协调控制。本发明为针对集散式控制架构的变换器的通信协议,在变换器启动前增加了通信自检功能,在系统启动前进行通信链路的检查,提高了变换器通信可靠性。同时,为保证通信的速度,通信自检数据与通信有效数据之间进行状态装换,通信自检完成后,通信链路间只进行有效数据的传输,同时保持了主控单元和模块控制单元之间的通信速率与可靠性。(The invention discloses a communication method aiming at the modular design of a photovoltaic direct-current boost converter, a module input parallel/output serial (IPOS) combined structure of a centralized photovoltaic direct-current boost converter is adopted, aiming at the circuit characteristics of an IPOS cascading scheme, a distributed control architecture is adopted by a system, a photoelectric isolation unit is used as a unified external interface between a main control unit and a module control unit, and the coordination control between the system and the module is realized by adopting optical fiber high-speed communication. The invention aims at the communication protocol of the converter with the distributed control architecture, a communication self-checking function is added before the converter is started, and the communication link is checked before the system is started, so that the communication reliability of the converter is improved. Meanwhile, in order to ensure the communication speed, the communication self-checking data and the communication effective data are exchanged, after the communication self-checking is finished, only the effective data are transmitted between communication links, and meanwhile, the communication speed and the reliability between the main control unit and the module control unit are kept.)

1. A communication method aiming at photovoltaic direct current boost converter modular design is disclosed, wherein a main control controller and a plurality of module control units are connected through a unified optical fiber interface, and the communication method is characterized by comprising the following steps:

step 1, carrying out communication self-check between a main control unit and a module unit before a converter runs, and judging to finish optical fiber communication link check between the main control unit and the module unit;

step 2, if the variable main control unit and all the modules complete communication self-checking, the main control unit transmits separator data and phase shift angle data to the module controller, so that all the modules run in an interlaced mode, and output current ripples are reduced; then, only the transmission of the effective data duty ratio is carried out between the main control unit and the module unit, and the communication self-check and the normal communication are decoupled, so that the running speed between the main control unit and the module unit is kept;

and 3, if the variable main control unit and all the modules do not finish communication self-checking, the main control unit can always circulate the communication self-checking function, and the equipment cannot be started at the moment, so that the reliability of communication between the main control unit and the module units is ensured, the equipment fault caused by the communication fault after the equipment is started is avoided, and the equipment is protected.

2. The communication method for the modular design of the photovoltaic direct current boost converter according to claim 1, characterized in that:

for guaranteeing the operating condition that centralized control ware high efficiency received the module, and carry out the fast action protection to the module when the trouble, specifically include to certain module emergence electric current overcurrent fault, module control unit at first protects, then module control unit changes to the module operation code that the main control unit sent to the main control unit through high-speed optic fibre, the main control unit sends the shutdown command to remaining module after receiving the operation code of trouble, remaining module stall, the quick response time of main control unit to module trouble has been guaranteed, module control unit optic fibre sending end divide into low-speed mouth and high-speed mouth, realize the main control unit to the quick protection of module, the main control unit received the multichannel sampling data of module when guaranteeing the quick high-efficient operation of converter, know the operating condition of module.

3. The communication method for the modular design of the photovoltaic direct current boost converter according to claim 1, characterized in that: in step 2, the main control unit transmits data to the module control unit through the optical fiber, a sending program module of the main control unit includes a plurality of states, the sending program module has six states of s0, s1, s2, s3, s4, s5, and s6, the main control unit enters a standby state after the program is started (s0), after receiving a start command sent by the upper computer, the program jumps to a communication self-checking state (s1), the main control unit sends communication self-checking codes to the module control unit in a circulating manner until the main control unit receives the communication self-checking codes returned by all the module units, and then the main control unit sends a separator (s2) to the module control unit in a circulating manner, the main control unit sends a phase angle (s3) to the module control unit in a circulating manner, the main control unit sends a CRC code (s4) to the module control unit in a circulating manner, and then the main control unit sends a duty ratio (s5) and a duty ratio data check code (s6, the master unit cannot jump out of the loop until it again receives the start command, jumping to the state standby state (s 0).

4. The communication method for the modular design of the photovoltaic direct current boost converter according to claim 1, characterized in that: the module control unit transmits data to the main control unit through a high-speed optical fiber, a sending program module of the module control unit comprises a plurality of states, the sending program module comprises four states of s0, s1, s2, s3 and s4, the module control unit enters a standby state (s0) after the program is started, when a self-checking code sent by the main control unit is received, the program jumps to a communication self-checking state (s1), and the module control unit circularly sends the communication self-checking code to the main control unit until the module control unit receives a separator sent by the main control unit; after that, the module control unit sends the module running state code (s2) to the master control unit in a circulating way, and the module control unit sends the module output current (s3) and the CRC code (s4) of the corresponding data to the master control unit in a circulating way, and the master control unit can jump out of the circulation and jump to the state standby state (s0) until the module control unit receives the communication self-check code again.

5. The communication method for the modular design of the photovoltaic direct current boost converter according to claim 1, characterized in that:

the module control unit transmits data to the main control unit through a low-speed optical fiber, the sending program module at the moment comprises a plurality of states, the sending program module comprises eight states of s0, s1, s2, s3, s4, s5, s6, s7 and s8, the module control unit enters a standby state (s0) after the program is started, the program jumps to a communication self-checking state (s1) after the self-checking code sent by the main control unit is received, and the module control unit circularly sends the communication self-checking code to the main control unit until the module control unit receives a separator sent by the main control unit; after that, the module control unit sends the module input voltage value (s2), the module clamping capacitor voltage value (s3), the module inductance current value (s4), the module IGBT arm temperature 1(s5), the module IGBT arm temperature 2(s6), the module IGBT arm temperature 3(s7) and the CRC check code (s8) of the corresponding data to the main control unit in a cycle, and the main control unit can jump out of the cycle and jump to the state standby state (s0) until the module control unit receives the communication self-check code again.

Technical Field

The invention relates to the field of power electronics, in particular to a communication method aiming at the modular design of a photovoltaic direct-current boost converter.

Background

In order to adapt to wide-range change characteristics of photovoltaic output power and voltage, a system integration and control technology of a high-efficiency DC/DC boost converter is researched. The photovoltaic direct-current boost converter adopts a modular design, and the design requirements of high voltage, high power and high boost ratio of the converter are realized in a module Input Parallel Output Series (IPOS) mode. In the prior art, the resource allocation of the main control unit of the multi-module system is difficult, and meanwhile, the voltage of the modules in operation is unbalanced due to complete distributed control, so that system faults are easily caused.

Disclosure of Invention

The invention aims to realize high-speed and reliable operation of communication between a main control unit and a module control unit of a photovoltaic direct-current boost converter. In order to realize a distributed control architecture, the invention provides a communication protocol aiming at the modular design of a photovoltaic direct-current boost converter, and a communication link is detected before equipment runs, so that the communication reliability is improved while the communication speed is ensured. Aiming at the circuit characteristics of the IPOS cascade scheme, a distributed control architecture is adopted, a photoelectric isolation unit is used as a unified external interface between a main control unit and a module control unit, and the coordination control between the system and the modules is realized by adopting optical fiber high-speed communication. The scheme adopts a mode of combining system centralized control and module decentralized control, effectively solves the problem of resource allocation of the main control unit of the multi-module system, and avoids the risk of system faults caused by unbalanced module voltage in operation due to complete decentralized control.

The main control unit and the module unit adopt a serial port (UART) communication protocol, and the main control unit sends communication self-check data, module operation data and a shutdown command to the module unit after receiving a power-on command. And the module control unit receives the data sent by the main control unit and sends the running state of the module, the module sampling data and the like to the main control unit. In order to ensure the rapid protection of the main control unit, a module sending port is divided into a low-speed port and a high-speed port, the high-speed port transmits the running state of the module, and the transmitted data is few and the speed is high, so that the main control unit can rapidly protect; the sampling data of the low-speed port transmission module is transmitted at a low speed, so that the main control unit can read the running data of the module.

After the module unit receives the self-checking data of the main control unit, the self-checking data of the module is returned to the main control unit through the sending port of the module control unit, and after the main control unit receives the self-checking data returned by all the modules, the communication self-checking of the system is completely completed, so that the accuracy of communication is ensured. And then, the main control unit and the module control unit are all in a normal operation state, and only effective data is transmitted between the main control unit and the module unit, so that the rapidity of communication is ensured.

The technical scheme of the invention is as follows: a communication method aiming at the modularized design of a photovoltaic direct-current boost converter is disclosed, wherein a master control controller and a plurality of module control units are connected through a unified optical fiber interface, and the communication method comprises the following steps:

step 1, carrying out communication self-check between a main control unit and a module unit before a converter runs, and judging to finish optical fiber communication link check between the main control unit and the module unit;

step 2, if the variable main control unit and all the modules complete communication self-checking, the main control unit transmits separator data and phase shift angle data to the module controller, so that all the modules run in an interlaced mode, and output current ripples are reduced; then, only the transmission of the effective data duty ratio is carried out between the main control unit and the module unit, and the communication self-check and the normal communication are decoupled, so that the running speed between the main control unit and the module unit is kept;

and 3, if the variable main control unit and all the modules do not finish communication self-checking, the main control unit can always circulate the communication self-checking function, and the equipment cannot be started at the moment, so that the reliability of communication between the main control unit and the module units is ensured, the equipment fault caused by the communication fault after the equipment is started is avoided, and the equipment is protected.

Further, for guaranteeing the operating condition of the fast and efficient receiving module of the centralized controller, and carry out fast action protection to the module when the trouble, specifically include that the electric current overflows the trouble to certain module emergence, module control unit at first protects, then module control unit changes to the module operation code that the main control unit sent to the main control unit through high-speed optic fibre, main control unit sends the shutdown command to remaining module after receiving the operation code of trouble, remaining module stall, the fast response time of main control unit to module trouble has been guaranteed, module control unit optic fibre transmitting terminal divide into low-speed mouth and high-speed mouth, realize the fast protection of main control unit to the module, the main control unit receives the multichannel sampling data of module when guaranteeing the fast and efficient operation of converter, know the operating condition of module.

Further, in step 2, the main control unit transmits data to the module control unit through the optical fiber, a sending program module of the main control unit includes a plurality of states, the sending program module includes six states of s0, s1, s2, s3, s4, s5 and s6, the main control unit enters a standby state (s0) after the program is started, after receiving a start command sent by the upper computer, the program jumps to a communication self-checking state (s1), the main control unit sends communication self-checking codes to the module control unit in a circulating mode until the main control unit receives the communication self-checking codes returned by all the module units, and then the main control unit sends a separator (s2) to the module control unit in a circulating mode, the main control unit sends a phase shift angle (s3) to the module control unit in a circulating mode, the main control unit sends a phase shift angle CRC check code (s4) to the module control unit in a circulating mode (s5) and a duty ratio data check code (s6), the master unit cannot jump out of the loop until it again receives the start command, jumping to the state standby state (s 0).

Furthermore, the module control unit transmits data to the main control unit through a high-speed optical fiber, a sending program module of the module control unit comprises a plurality of states, the sending program module has four states of s0, s1, s2, s3 and s4, the module control unit enters a standby state (s0) after the program is started, when a self-checking code sent by the main control unit is received, the program jumps to a communication self-checking state (s1), and the module control unit circularly sends the communication self-checking code to the main control unit until the module control unit receives a separator sent by the main control unit; after that, the module control unit sends the module running state code (s2) to the master control unit in a circulating way, and the module control unit sends the module output current (s3) and the CRC code (s4) of the corresponding data to the master control unit in a circulating way, and the master control unit can jump out of the circulation and jump to the state standby state (s0) until the module control unit receives the communication self-check code again.

Further, the module control unit transmits data to the main control unit through a low-speed optical fiber, the sending program module at this time includes a plurality of states, the sending program module includes eight states of s0, s1, s2, s3, s4, s5, s6, s7, and s8, the module control unit enters a standby state (s0) after the program is started, and when receiving the self-checking code sent by the main control unit, the program jumps to a communication self-checking state (s1), and the module control unit sends the communication self-checking code to the main control unit in a circulating manner until the module control unit receives the separator sent by the main control unit; after that, the module control unit sends the module input voltage value (s2), the module clamping capacitor voltage value (s3), the module inductance current value (s4), the module IGBT arm temperature 1(s5), the module IGBT arm temperature 2(s6), the module IGBT arm temperature 3(s7) and the CRC check code (s8) of the corresponding data to the main control unit in a cycle, and the main control unit can jump out of the cycle and jump to the state standby state (s0) until the module control unit receives the communication self-check code again.

The invention has the beneficial effects that:

1) the invention can carry out communication self-check between the main control unit and the module unit before the converter runs, completes the optical fiber communication link check between the main control unit and the module unit, ensures the reliability of communication between the main control unit and the module unit, avoids equipment failure caused by communication failure after the equipment is started, and protects the equipment;

2) according to the invention, after the converter completes communication self-check, only effective data transmission is carried out between the main control unit and the module unit, so that decoupling between the communication self-check and normal communication is realized, and the running speed between the main control unit and the module unit is kept;

3) the module control unit is divided into a low-speed port and a high-speed port, so that the module is quickly protected by the main control unit, and the main control unit can receive multi-path sampling data of the module and know the running state of the module while ensuring the quick and efficient running of the converter.

Drawings

FIG. 1 is a block diagram of the distributed control protection system of the present invention;

FIG. 2 is a diagram of a master control unit communication transmission control state transition;

FIG. 3 is a diagram of a module control unit high speed communication transmission control state transition;

fig. 4 is a low-speed communication transmission control state transition diagram of the module control unit.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.

As shown in fig. 1, the control system of the photovoltaic dc boost converter includes a main control unit and a plurality of module control units. The photoelectric isolation unit is used as a unified external interface between the main control unit and the module control unit, and the coordination control between the system and the modules is realized by adopting optical fiber high-speed communication. In order to realize the high-speed and reliable operation of the whole converter, the invention designs a communication method (namely a communication protocol) aiming at the converter with a distributed control architecture, the communication method of the invention adds a communication self-checking function before the converter is started, and the communication link is checked before the system is started, thereby improving the communication reliability of the converter. Meanwhile, in order to ensure the communication speed, the communication self-checking data and the communication effective data are exchanged, after the communication self-checking is finished, only the effective data are transmitted between communication links, and meanwhile, the communication speed and the reliability between the main control unit and the module control unit are kept.

Table 1 lists the data transmitted by the main control unit and the module control unit through the optical fiber. The two optical fibers of the module control unit adopt the same optical fiber interface, low-speed transmission and high-speed transmission are realized by adopting different data sending modes, the data transmitted by the high-speed optical fibers are few, the running state code and the module output current of the main transmission module ensure that the main control unit quickly receives the running state of the module, and when the module breaks down, the main control unit quickly protects the module. The data transmitted by the low-speed optical fiber is more, 6 paths of sampling data of the transmission module are transmitted, and the main control unit can observe the operation data of the multi-path module.

TABLE 1 centralized and distributed control system optical fiber transmission data table

As shown in fig. 2 and table 2, the state transition diagram of the data and the sending program transmitted from the main control unit to the module control unit through the optical fiber according to the present invention includes six states s0, s1, s2, s3, s4, s5, and s6, and includes the following steps:

step 1, the main control unit enters a standby state after the program is started (s0), and after a starting command sent by the upper computer is received, the program jumps to a communication self-checking state (s1), and at the moment, the main control unit sends communication self-checking codes to the module control unit in a circulating mode until the main control unit receives the communication self-checking codes returned by all the module units.

Step 2, the main control unit sequentially sends separators to the module control unit (s 2);

step 3, the main control unit sequentially sends the phase shift angle of the separator to the module control unit (s 3);

step 4, the main control unit sequentially sends phase shift angle CRC check codes to the module control unit (s 4);

and 5, the main control unit sends the duty ratio (s5) and the duty ratio data check code (s6) to the module in a cycle mode until the main control unit receives the starting command again and then jumps out of the cycle mode to a state standby state (s 0).

In the process, step 1, the centralized controller transmits communication self-check data to all modules, and before the main control unit receives communication self-check codes returned by all the modules, the main control unit circularly transmits the self-check data to the module control unit; step 2, sending separator data to the module control unit to remind the module control unit that valid data is to be received next after system communication self-check is completed; step 3, the main control unit sends phase shift angle data to the module control unit, so that all modules run in a staggered mode, and output current ripples are reduced; and 4, circularly sending duty ratio data to the modules by the main control unit to realize that the main control system controls the operation of the multiple modules.

Table 2 master control unit communication transmission control state machine description

As shown in fig. 3 and table 3, the state transition diagram of the data and the sending program transmitted by the module control unit to the main control unit through the high-speed optical fiber according to the present invention includes four states s0, s1, s2, s3, and s4, the module control unit enters a standby state (s0) after the program is started, and when receiving the self-check code sent by the main control unit, the program jumps to a communication self-check state (s1), and the module control unit circularly sends the communication self-check code to the main control unit until the module control unit receives the separator sent by the main control unit. Thereafter, the module control unit cyclically transmits the module operation state code (s2), the module output current (s3) and the CRC check code (s4) of the corresponding data to the master control unit, and the master control unit cannot jump out of the cycle until the module control unit receives the communication self-check code again, and jumps to the state standby state (s 0).

TABLE 3 Module control Unit high speed communication Transmit control State machine Specification

As shown in fig. 4 and table 4, the state transition diagram of the data and the sending program transmitted by the module control unit to the main control unit through the low-speed optical fiber according to the present invention includes eight states s0, s1, s2, s3, s4, s5, s6, s7, and s8, the module control unit enters a standby state (s0) after the program is started, and when the self-checking code sent by the main control unit is received, the program jumps to a communication self-checking state (s1), and the module control unit circularly sends the communication self-checking code to the main control unit until the module control unit receives the separator sent by the main control unit. After that, the module control unit sends the module input voltage value (s2), the module clamping capacitor voltage value (s3), the module inductance current value (s4), the module IGBT arm temperature 1(s5), the module IGBT arm temperature 2(s6), the module IGBT arm temperature 3(s7) and the CRC check code (s8) of the corresponding data to the main control unit in a cycle, and the main control unit can jump out of the cycle and jump to the state standby state (s0) until the module control unit receives the communication self-check code again.

TABLE 4 Module control Unit Low speed communication Transmit control State machine Specification

The communication receiving program of the main control unit and the module control unit corresponds to the sending program, and the sending data is received in sequence, which is not described herein.

Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but various changes may be apparent to those skilled in the art, and it is intended that all inventive concepts utilizing the inventive concepts set forth herein be protected without departing from the spirit and scope of the present invention as defined and limited by the appended claims.