Bus network

About: Bus network is a research topic. Over the lifetime, 7017 publications have been published within this topic receiving 97556 citations.

Methods and apparatus for bus access arbitration of nodes organized into acyclic directed graph by cyclic token passing and alternatively propagating request to root node and grant signal to the child node

Abstract: A bus arbitration scheme is implemented in a system where an arbitrary assembly of nodes on a system bus have been resolved into an acyclic directed graph The hierarchical arrangement of nodes has one node designated a root while all other nodes have established parent/child relationships with the nodes to which they are linked Each node may have a plurality of connected child ports with a predetermined acknowledgment priority scheme established Fair bus access arbitration provides for bus granting in a sequence corresponding to the predetermined port priorities allowing all nodes a turn on the bus The root node may always assert its priority access status to gain bus access which is useful for accommodating a root node which requires isochronous data transfer Alternatively, a token passing arbitration scheme may be implemented where the token for bus access is passed around the nodes according to the above-described predetermined port priority scheme Preemptive bus initialization may be triggered by any node upon detection of a necessitating error or addition or removal of a connection to an existing node

Performance Analysis of IEC 61850 Sampled Value Process Bus Networks

Abstract: Process bus networks are the next stage in the evolution of substation design, bringing digital technology to the high-voltage switchyard. Benefits of process buses include facilitating the use of nonconventional instrument transformers, improved disturbance recording and phasor measurement, and the removal of costly, and potentially hazardous, copper cabling from substation switchyards and control rooms. This paper examines the role a process bus plays in an IEC 61850-based substation automation system. Measurements taken from a process bus substation are used to develop an understanding of the network characteristics of “whole of substation” process buses. The concept of “coherent transmission” is presented, and the impact of this on Ethernet switches is examined. Experiments based on substation observations are used to investigate in detail the behavior of Ethernet switches with sampled value traffic. Test methods that can be used to assess the adequacy of a network are proposed, and examples of the application and interpretation of these tests are provided. Once sampled value frames are queued by an Ethernet switch, the additional delay incurred by subsequent switches is minimal, and this allows their use in switchyards to further reduce communications cabling, without significantly impacting operation. The performance and reliability of a process bus network operating close to the theoretical maximum number of digital sampling units (merging units or electronic instrument transformers) was investigated with networking equipment from several vendors and has been demonstrated to be acceptable.

High speed multimedia data network

Abstract: A low cost, high speed multimedia data network is disclosed. The network preferably includes a fiber optic data bus arranged in a star topology configuration. Various types of devices or nodes may be placed in communication with the bus via a specially designed interface. The interface allows a device to communicate with the high speed network without requiring that the device have the processing power to receive and transmit data according to the protocols and demands of the network. The interface may be configured to match the complexity of its associated device. For intelligent devices, the interface may allow some of the network-related functions to be performed by the device itself. For non-intelligent (or "dumb") devices, the interface performs substantially all of the network-related functions. In general, the interface provides the capability of insulating a node from the complexities of the high speed network by receiving data from and providing data to the node according to the node's data format, and receiving data from and providing data to the network according to the network's data format. The general messaging protocols are designed to facilitate the transfer of data in a star topology configuration, while also facilitating the relatively low cost and flexible implementation of the network.

Locomotive power train architecture

Abstract: The present invention is directed to a power control architecture for a vehicle, particularly a locomotive, in which a number of energy sources (105, 111, 115) are connected to a common electrical bus (101, 102) and selectively provide energy to the bus (101, 102) based on the relationship between their respective output voltages and the bus voltage

Bus Selection in Multibus DC Microgrids

Abstract: DC power systems can be made more reliable by using multiple buses for redundancy. Multiple buses provide multiple configuration options for supplying power to the load. Diode OR'ing with auctioneering diodes is perhaps the most common method to connect a load to multiple buses. Although the diode action is automatic and fault-tolerant, it results in ill-defined bus currents when the bus voltages are similar and the potential for uncontrolled switching in a faulted high-impedance system-operating scenarios not often included in a discussion on auctioneering diodes. Active switching and bus converters with auctioneering diodes are control techniques that overcome these limitations by providing full control over the bus selection process. Using local information in the form of the bus voltage, these techniques do not rely on a centralized controller, which improves system reliability. Dwell time is proposed as a technique to stabilize the state-dependent switching in the bus selector.