1 Introduction
Sibas32 is a dedicated microcomputer control system developed by Siemens AG, Germany, specifically for the control of railway locomotives and trains. Its full name is Siemens Railway Automation System. The Sibas32 system is designed with the future development of key functions for drive unit control in mind, thus imposing extremely stringent requirements on the system. It is a high-performance general-purpose computer system that can be connected to any device through standard and dedicated peripheral components, essentially capable of performing all control and monitoring tasks for locomotives and trains. The Sibas32 system can process driver commands, traction circuit status, and response signals accordingly, issuing control signals to various contactors, relays, solenoid valves, LEDs or digital displays, choppers, etc. The control unit can also perform various monitoring functions, including diagnosing its own functions and monitoring external values exceeding limits. When the traction circuit exceeds the pre-set upper (or lower) limits during operation, the system will take appropriate action based on the severity of the fault, automatically recording the fault, generating corresponding protection, and notifying the driver. The biggest advantage of the Sibas32 system is that it is applicable to the control of various vehicles. Whether it is a phase-controlled rectifier locomotive, a chopper locomotive or an AC drive locomotive, the locomotive can be controlled by simply changing the corresponding control program without changing its basic hardware structure.
2. Features of the Sibas32 system
The SIBAS32 system implements adjustment and logic control functions for the GHD1 locomotive. For faults occurring during testing or operation, it can display the fault and implement relevant protection measures through the human-machine interface within a short time. During locomotive fault diagnosis, the SIBAS Expert2 diagnostic software analyzes the hardware and software causing the fault, improving maintenance efficiency and fault diagnosis accuracy. Furthermore, the monitor software can detect and simulate relevant signals to locate the fault location and cause in real time, accurately identifying the faulty component. The SIBAS32 system has the following characteristics:
(1) The entire locomotive control system adopts a large-capacity signal processor module, a dedicated software function integrated block, and a highly integrated circuit to ensure the reliable operation of the locomotive.
(2) The Sibas32 system uses the Sibasg design language for logic design and processing. This design system supports the entire process from input and compilation to automatic file generation, thus obtaining a universally applicable system with a unified design entry point and standard. Therefore, designing a new control system does not require changing a large number of hardware devices; only some software control logic needs to be modified to achieve the design objective.
(3) To reduce traditional locomotive and rolling stock wiring, Sibasklip (SKS1A, SKS1B, SKS3) devices (intelligent peripheral connection terminals) are installed. Using Sibasklip, control commands and information can be quickly integrated, transmitting commands to the central control unit accurately and promptly via a simple twisted-pair cable. The Sibasklip station consists of a programmable controller (composed of a CPU and Simatic memory), input ports, and output ports. Due to its robust structure and ease of disassembly, it can be freely and flexibly installed on the locomotive.
(4) In order to expand the diagnostic functions already installed in the Sibas32 system, Siemens developed the Sibas Expert system (SibasExpert2). Using this expert system, the computer-aided functions can be used to effectively analyze the data and contents stored in the diagnostic system. When necessary, the scope of information query can be expanded or narrowed to quickly locate the fault.
(5) The increasingly large-capacity intelligent operation and image display devices can achieve high-capacity human-machine communication through serial bus connection. The HXD1 locomotive uses a color LCD display. By expanding the integrated computer capacity of this display device, all tools developed for personal computers can be used to modify and supplement it; moreover, its internal operating system adopts the Windows 32 system, which is more convenient to maintain.
(6) It can not only display the required operating information to the driver, but also the actions to be taken in case of a malfunction. Maintenance personnel can use this interface to obtain further instructions for troubleshooting; at the same time, they can call up the precise spatial layout diagram of the parts to be controlled or replaced, and provide additional operating instructions.
Therefore, it is evident that the Sibas32 system will be used more widely than any other locomotive and train control system.
3. Structure of the Sibas32 system
The Sibas32 system has a simple structure and adopts a distributed control mode. It consists of CCU, TCU, MMI, SKS1 (SKS1a, SKS1b), SKS3, Locotrol, etc. The Sibas32 control block diagram applied to the HXD1 locomotive is shown in Figure 1.
Figure 1. Control block diagram of locomotive 1hxd1
As can be seen from the diagram, SKS1, CCU, TCU, etc. are dual-redundant. Up to two locomotives (4 cars) can be coupled together via the train bus, and four locomotives (8 cars) can be coupled together wirelessly via Locotrol. This provides a reliable technical guarantee for the heavy-haul transportation of 10,000 tons on the Daqin Railway.
3.1 Central Control Unit (CCU) (Central Control Unit Type 3)
The CCU is the core unit of the entire system, responsible for the control, regulation, and monitoring of the locomotive. The HXD1 locomotive's CCU uses a Type 3 32-bit microprocessor, consisting of a gateway, CPU, MVB32-4, and power supply. It can support up to two locomotives (four cars) operating in parallel. The CCU employs a redundant design, with two CCUs per car: a master CCU and a slave CCU. Both have identical structure and function; if one fails, the other can continue operating without affecting the locomotive's normal operation.
The main functions of the CCU are to store the parameter settings of the locomotive in this section, record the events of the locomotive in this section, display the events of the locomotive in multiple-unit operation, detect the communication of the whole vehicle, read or dump data through the RS232 interface, and serve as the input port for uploading the system software of the locomotive central control unit.
3.2 Traction Control Unit (TCU)
The TCU (Train Control Unit) is the core control unit for locomotive traction, consisting of a central processing unit module, a memory module, a chopper control module, a digital interface module, a digital input/output module, an analog interface module, a control system detection module, a train control signal input conversion module, a digital signal input conversion module, a contactor drive module, an IGBT trigger module, and a starting unit. Its function is to control and regulate locomotive traction and regenerative braking, electrically provide anti-slip/coasting protection, and implement open-loop and closed-loop control, speed and frequency synchronization, fault handling, and monitoring.
3.3 Intelligent terminal interface units sks1a, sks1b, sks3 (sibaskilp)
SKS1A, SKS1B, and SKS3 are intelligent peripheral device connection terminals. SKS1A and SKS1B are compact digital input/output interfaces designed for use in the driver's cab. They convert driver control commands into digital signals and transmit the signals to the CCU through encoding. SKS3 adopts distributed input/output, reducing the wiring required in the vehicle and increasing control and diagnostic capabilities.
3.4 Monitor MMI
Each driver's cab has an MMI display containing a microcomputer processing unit. The MMI provides locomotive information status, fault information, and settings for actions taken and information updates. It supports Chinese-English language switching, runs on a Windows 32-bit operating system, and uses a Windows graphical user interface. The MMI communicates with the CCU via an MVB interface, allowing users to modify the time, locomotive number, and other locomotive parameters displayed on the monitor using a laptop.
3.5 Train Communication Network (TCN)
The Train Communication Network (TCN) consists of two parts: the Train Bus (WTB) and the Multi-Function Vehicle Bus (MVB). It adopts a redundant design, so if one bus fails, data can be exchanged on the other. The WTB is responsible for external communication between locomotive sections A and B, as well as between locomotive sections, while the MVB is responsible for internal communication within a single locomotive section.
The TCN network physical layer consists of copper twisted-pair cables with a data transmission rate of 1 Mbit/s. The WTB bus is 850m long, and the MVB bus is 200m long. To improve the reliability of the TCN bus system, a full-system redundancy design is employed. Each train bus node has four interfaces; each individual bus node has one normal interface and one redundant interface, with each interface connecting to the previous and next nodes; each bus cable is laid from one node to another, forming a closed loop at each bus node. At the bus terminal nodes, a relay on the gateway connects to a matching resistor.
4. Sibas32 graphical schematic design software Sibasg
One of the most prominent features of the Sibas32 system is its fully graphical design, using the Sibasg language as the development and design tool. It effectively supports the entire design process with simple tools, and the graphical design is displayed on the screen. Designers can use the functional blocks in the Sibasg library to call the smallest blocks to construct the software for the entire device. It uses the mouse to locate itself on its function chart and connects with each other through simple input and output pairings; the names of the blocks and signals are determined by the designer according to design requirements. Therefore, users do not need relevant professional knowledge to use this tool during design, use, maintenance, and modification, and can perform technical processing just like with traditional block diagrams. More importantly, designers do not need to consider the technical conditions of all data related to the actual processing program in the computer. The entire function of the Sibas32 system is represented and processed in several different levels: control program → function package → function component → image electronic magnification. The lowest level is the functional block. Several blocks can be combined to form a function component, several function packages are composed of several function components, and finally all function packages constitute a complete program. Due to the outside-in unfolding and electronic image magnification, when working with this system, desired sub-functions can be directly accessed. Furthermore, high-resolution processing can be used for fine details, while a more intuitive, dense representation can be selected in other situations.
Graphical design can be automatically compiled within a computer using the required code, and simultaneously verified. However, extensive checks cannot be performed during function chart input, so a validated, executable computer program is then used. Sibasg's structure is manually operated and entirely document-driven, automatically providing documentation for control functions during the design process, thus always utilizing real-time data. This continuous density of computer programs and documentation represents a significant improvement in both quality (it ensures zero errors) and time efficiency (work data is always real-time). Therefore, the screen display is completely consistent with the document display.
The functional integration blocks themselves are written in the C programming language. It is precisely because of this high-level language that sibasg itself is processor-independent, allowing for easy replacement with newer processors. It's worth noting that the programs generated by sibasg are processor-dependent and must be changed when the processor model is modified. This ensures that future hardware improvements can be made without developing risky software or incurring excessive development costs.
Figure 2 shows the following: the left side displays the project list (48 projects in version 7.00), the middle side displays the detailed list, and the right side displays the detailed logic control schematic. The figure also shows that the CCU control software is controlled by related signals through logical relationships. The monitor software can test the related logic, thereby speeding up fault diagnosis; it can also simulate faults by modifying related signals to reproduce the faults. Due to technology transfer, the CCU software design has been delivered to Zhuzhou Electric Locomotive Co., Ltd., and will not be discussed in detail here.
Figure 2. Sibasg software design interface
5. Application of Diagnostic Software (SibasExpert2)
Once the locomotive enters the depot's maintenance yard, maintenance personnel use the sibasexpertcom program on their laptops to download data from sections A and B of the locomotive via the RS232 port, and then send the data to the depot's local area network server. This allows technicians to analyze the data using the sibasexpert2 (customer version) software. sibasexpert2 is a 32-bit application that runs on Windows 2000 and Windows XP, but is currently not compatible with Windows Vista. Based on requests from Chinese users, Siemens has localized the software for easy use.
5.1 Installation of Diagnostic Software
Users install the Sibasexpert2 program using the installation disc and method provided by Siemens. Due to Siemens' technical confidentiality and protection of locomotive setting data, users are using a client version. However, through technology transfer and other technical means, users now essentially possess the relevant user privileges. Although the actual functionality of the software is no longer restricted, Siemens downloads and analyzes detailed TCU data using DSP software. Currently, the Chinese side lacks relevant software and is attempting to develop it. 5.2 Data Analysis and Fault Troubleshooting
(1) Data Analysis. First, open sibasexpert2.exe in the program bar and click to import the locomotive data that needs to be diagnosed. Then, in the sibasexpert2 interface, click to start a regular spreadsheet, where you can see detailed records of events occurring in the CCU and TCU. How can we quickly determine the location of the fault by analyzing the event records of the CCU and TCU? The following uses the fault that occurred in section B of locomotive HXD10077 as an example to explore the fault finding method of locomotive HXD1.
For example, on September 5, 2008, locomotive HXD10077 experienced multiple instances of main circuit breaker tripping due to TCU issues. Analysis of the downloaded data revealed that 34 faults occurred simultaneously within a few seconds. The fault code 85, "ground fault detected," occurred earliest, and fault code 86, "inverter ground fault detected," was also detected. Consequently, the automatic switches of the inverter and TCU2 were temporarily disconnected.
(2) Troubleshooting. Since the grounding detection of the main inverter is determined by the ratio between the output voltage of the intermediate DC link voltage sensor and the output voltage of the grounding link voltage sensor, the fault codes 85 and 86 indicate the following possible faults:
There is indeed a grounding fault, namely the grounding of the 3rd and 4th motors and the grounding of the wiring between the main inverter module and the 3rd and 4th motors; the detection circuit has a fault, namely the grounding resistance value is incorrect or the grounding voltage sensor is faulty; the judgment circuit has a fault, namely the voltage sensor input board (l095) of TCU2 or the voltage control and monitoring board (g019) of the main inverter is faulty.
On-site testing showed that the signals $zfqmd and $tcntqmd were normal (frequency code 3, delay 600). Therefore, the TCU hardware was determined to be without fault, meaning the third type of fault did not exist, and the test motor was found to be ungrounded. The grounding resistance and grounding voltage sensors of the two locomotive sections were swapped, and a high-low voltage test was performed. The locomotive then exhibited the same fault again. Therefore, the fault was found to be in the wiring from the main inverter module to the 3rd and 4th motors. By hoisting the auxiliary transformer, it was discovered that the terminals of the 3rd and 4th motors were burnt out and grounded. After replacing the damaged motor terminals, the locomotive operated normally.
6. Conclusion
With the development of AC drive control technology in China, field operators need to continuously and deeply study the SIBAS32 microcomputer control system to gradually achieve localization and thus realize the goal of introducing, absorbing, digesting, and re-innovating new technologies. Furthermore, with the widespread use of AC locomotives in China, field operators will increasingly rely on analysis software to analyze and solve problems, which will provide valuable reference for the design and manufacturing of domestically produced locomotives.
