In recent years, the centralized control system and train fusion control technology has been paid more and more attention. The software architecture of braking system under the fusion framework needs to be upgraded and redesigned.The traditional train basically adopts the way of setting a specific controller and software for each specialty, which can not achieve the simplification and reuse of vehicle equipments;For the design of braking system, on the other side,the contradiction between functional safety, standardization and project customization and system diversification are increasingly obvious.Based on the above problems, a new control architecture is proposed to decompose the existing braking system functions: While the traditional BCU retains the safety architecture and executive functions, the remaining functions associated with the other control specialties are stripped down into a separate brake application software, which may be further broken down into a set of service subscription， deployed in different centrailized train control fusion systems. Braking functions under the new architecture are graded according to safety requirements and service scope. Local level, SIL3 and above safety functions are implemented by the BCU with the help of traditional hardware architecture, while the vehicle level, SIL2 and below safety functions are packaged as brake service applications and installed in the fusion controller.The brake application software and BCU communicate with each other using security protocols to complete all braking functions.In the process of developing ametro experimental train using this architecture, with the help of the basic service API and other middle-ware, the braking application and other train control systems realized the real-time data exchange at the memory level by using a virtual bus in the fusion host, and finally the centralized train control.The BCU under the vehicle was used as the local execution device,while its interface and hardware were fixed as a standard interface;Brake application software can provide different services within the SIL2-level fusion control host according to the project configuration and functional requirements.Practical experience shows that the braking function can be successfully defined directly by software based on different project profiles and service subscriptions under the SOA architecture of high performance fusion system host, reducing development costs and delivery cycles, improving functional security and code versatility.

Mr. Le Wang, Technical Manager, China Academy of Railway Sciences; Mr. Yi Jiao, Technical Manager, Beijing Zongheng Electro-mechanical Technology Development Co