Generator Circuit Breakers (GCBs) are commonly used in electrical power generation systems to protect key equipment such as transformers and generators from damage due to overload or short-circuit. However the interruption and feeding of high currents lead to the ablation of the electrical contact system of the breaker. This deterioration process needs to be monitored in order to guarantee the healthy condition of the breaker. In this paper, we propose a virtual prototype of a GCB fitted with an ablation monitoring system. This is an early model of the complete system, which is highly desired before the physical implementation, since it facilitates the study of detection methods and the exploration of system limitations. The virtual prototype is implemented in VHDL-AMS with certain low-level models described in SPICE. The virtual prototype has been validated by measurements performed on the real system. It is therefore adequate for performing design optimization and to obtain useful observations for further usage of the monitoring system.

In this paper we give an overview of new requirements to the modeling and simulation of analog and mixed-signal systems. We give brief examples from two application domains and reveal limitations of established means for modeling and simulation. New challenges to modeling and simulation arise due to close functional coupling between analog hardware and DSP software, tremendous amount of data to be processed, and an increasing impact of physical effects to system behavior. As a potential solution the article discusses means for combining different models of computation

This paper focuses on commonalities and differences between the two mixed-signal hardware description languages, VHDL-AMS and Verilog-AMS, in the case of modeling heterogeneous or multidiscipline systems. The paper has two objectives. The first one is modeling the structure and the behavior of an airbag system using both the VHDL-AMS and the Verilog-AMS languages. Such a system encompasses several time abstractions (i.e., discrete-time and continuous-time), several disciplines, or energy domains (i.e., electrical, thermal, optical, mechanical, and chemical), and several continuous-time description formalisms (i.e., conservative-law and signal-flow descriptions). The second objective is to discuss the results of the proposed modeling process in terms of the descriptive capabilities of the VHDL-AMS and Verilog-AMS languages and of the generated simulation results. The tools used are the Advance-MS from Mentor Graphics for VHDL-AMS and the AMS Simulator from Cadence Design Systems for Verilog-AMS. This paper shows that both languages offer effective means to describe and simulate multidiscipline systems, though using different descriptive approaches. It also highlights current tool limitations, since full language definitions are not yet supported.

The ever increasing complexity of digital hardware, forces the hardware designer to switch from a low-level capture-and-simulation process to a high-level design-and-synthesis process. In order to assist the designer during the specification phase, we designed MODES, a new high-level specification environment. MODES integrates graphical specification capture in various behavioural representations, a facility to merge various specification formats, a high-level simulation tool and, finally, code generation for simulation and synthesis, e.g. in VHDL-1076, IEEE's hardware description language. Furthermore, some verification and consistency-check mechanisms have been integrated.>