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ObjectivesIn order to support the testing requirements of the international thermonuclear experimental reactor AC/DC converter system and apply to high-precision control standards for future fusion magnet power supplies, a real-time control system suitable for high-power DC test platforms was developed.MethodsChoosing the QNX real-time operating system as the core platform and combining it with reflective memory technology provided by GE company in the United States, a network architecture for real-time high-speed data exchange was built. The system was designed with multiple operation modes to cope with different testing scenarios, while implementing different levels of safety interlocking mechanisms to ensure equipment safety. This system possessed the capabilities of setting converter operating parameters, fault identification, equipment status monitoring, and millisecond-level real-time control and safety protection functions.ResultsExperimental validation has demonstrated the system’s stability and reliability in high-power environments, achieving precise control of 120 kA steady-state current and 500 kA pulse current. Furthermore, the system not only meets the basic requirements of real-time control but also ensures safe interlocking and continuous stable operation of the equipment during multi-mode operation.ConclusionsThe designed real-time control system for the high-power DC test platform achieves efficient multi-module synchronous management and fully complies with strict millisecond-level control cycle requirements.

Supervisory control system for superconducting magnet power supplies in JT-60SA is designed and developed. This system is in charge of many kinds of control; discharge sequence control, real-time magnet current control, data acquisition, machine protection and human safety. In the design, communication interface has to be optimized according to all requirements. The most important feature is real-time control with 4 kHz which is required for equilibrium control of plasma. In order to satisfy this requirement, reflective memory (RFM) network is applied for high speed data sharing with multiple controllers. This paper describes the architecture of the control system and the operation of the power supply system under the supervision. [ABSTRACT FROM AUTHOR]

Distributing control mechanisms across modern commercial off the shelf (COTS) GNU/Linux systems often introduces difficult to mitigate non-deterministic behavior. Existing methods to address this problem involve non-real-time technologies such as Remote Direct Memory Access (RDMA) over Infiniband or custom Ethernet solutions, such as RDMA over Converged Ethernet (RoCE) or userspace Ethernet drivers, that trade determinism for ease of use or lower cost. The National Spherical Torus Experiment Upgrade (NSTX-U) is pursuing a new design that allows direct communication between heterogeneous systems with scalable, microsecond latency with 1 μs of jitter on that latency, outside of the constant transmission delay at the physical layer. The future design of the NSTX-U Real-time Communication System will utilize direct PCIe-to-PCIe communication with kernel support tuned for low overhead, allowing two (or more, through a switch) real-time (RT) systems to communicate and share resources as one larger entity. This greatly increases the processing capability of the primary Plasma Control System (PCS), turning previously insurmountable computational challenges into a more manageable divide and conquer parallel task. [ABSTRACT FROM AUTHOR]

The plasma control system (PCS) of QUEST was a centralized system, which lost its scalability because of the overload imposed on its central processing unit (CPU) of the PCS, making it impossible to add new functions. Thus, the PCS is distributed into a main workstation (WS) and subsystem (SS) with a reflective memory (RFM) in order to share data between these systems so as to mitigate the load on each system. As a result, 128 double-precision floating-point numbers (DBLs) can be transferred from the SS to the WS with a maximum latency of 250 μs. The WS and the SS each have quad-core CPUs, and tasks are executed in parallel. Although one of the four cores is intermittently occupied by up to 90% by this transaction, the occupation is normally 60%. A time correction procedure is used to map the recorded data sets on the WS and the SS to a common time base by referring to the time difference between two systems. [ABSTRACT FROM AUTHOR]

Abstract: Reflective memory (RFM) is adopted as a real time network in the KSTAR plasma control system (PCS). Since the data uploaded from any computer are automatically shared among all the computers on the RFM network, the design of a distributed control system based on RFM is easily implemented through the management of memory mapping. The data providers and consumers are logically well seperated so that, if memory mapping information is given, a new control unit can be added without any modification to the existing system except connecting a new RFM module through an optical cable. The KSTAR PCS is also connected with the Ethernet in addition to the RFM because the RFM does not support the Transmission Control Protocol/Internet Protocol (TCP/IP) and many network services of the operating system such as the Network File System (NFS) and the Secure Shell (SSH) are based on the TCP/IP. Therefore we developed an Ethernet emulation driver for the RFM to eliminate the need for a separate Ethernet network. The driver was tested on the Linux kernel 2.6.31. The algorithm of the emulation driver is explained and the experimental setup is presented. [ABSTRACT FROM AUTHOR]