Focus on Electronics

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April 2002
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42-V global standardization

Japan has proposed a new 42-V minifuse standard that employs a polyamide material in place of standard polyethyl sulfur material as well as a cording with side ribless structure.

A group of automotive experts convened at the SAE 2002 World Congress to discuss the global harmonization of 42-V standards. The panel was moderated by Norman Traub, Director of SAE 42-V Initiatives. Panelists included Tatsuo Teratani, 42-V Project Manager for Toyota and Chairman of the newly formed 42-V Working Group in JSAE; Wolfgang Bremer from Robert Bosch GmbH; and Anson Lee from DaimlerChrysler, current Chairman of the United States Council for Automotive Research (USCAR) 42-V Working Group.

Vehicle manufacturers are faced with the challenge of providing more electrical power to offer more fuel-efficient and safer vehicles with additional customer features. A higher voltage system has been the focus of an MIT/Industry Consortium, as well as the Forum Bordnetz in Europe. All are in agreement that global cooperation and standardization will be needed.

Teratani led off the discussion with a short preview of the Crown, a THS-M 42-V mild-hybrid vehicle that is now in production in Japan. Toyota's third hybrid car features a 42-V power system consisting of about 20 different components, including compressor, engine, starter, electromagnetic clutch, motor/generator, inverter, dc/dc converter, electronic control unit, 12-V battery, and 36-V valve-regulated lead-acid battery.

Bremer continued the discussion with an overview of the International Standards Organization (ISO) 21848 standard development. Part 2 of the standard applies to electric/electronic systems/components for an automotive 42-V network and describes the potential stress requirements as well as the necessary testing. The committee's draft of the standard is due to be completed by the end of 2002, with a draft of an international standard finished by the middle of 2003 and development of the final version expected by the end of 2003.

Also involved in 42-V standard activities is USCAR. The group is charged with furthering current efforts to address the fundamental challenges and conversion priorities regarding the transition to 42-V systems. The organization is also looking to get the automotive industry to agree on common interfaces and performance standards to reduce cost, improve quality, and optimize the conversion to 42-V architectures. Four subgroups—battery terminal, jump-start, arcing, and regulations—have been formed to achieve this mission.

Traub concluded standardization discussions with an overview of SAE's activities regarding 42-V systems, including a 42-V advisory committee, a 42-V interior and exterior lighting cooperative research project, a U.S. technical advisory group, a 42-V professional development program, and a 42-V battery connection task force. SAE also hosted a 42-V professional development seminar via an interactive telephone/Webcast in March. For further information regarding SAE's 42-V activities, visit www.sae.org/42volt.

- Frank Bokulich

iQBus aids x-by-wire design

iQBus' comprehensive library contains 30,000 parts (models) spanning different engineering disciplines. Parts range from high-level control blocks to physical-component implementations, enabling modeling of systems such as an electromechanical brake illustrated here. Click to enlarge

Avant! Corp.'s iQBus system was developed to assist engineers in the development of x-by-wire systems, such as brake-by-wire. The company displayed the system at SAE 2002.

Because of the growing number of system variants, companies cannot test or predict the behavior of a final product with real hardware prototypes, according to Joachim Langenwalter and Bryan Kelly of Avant! Corp. Therefore, they must use an integrated tool package to design, simulate, and document systems used in automobiles, trucks, buses, trains, and other vehicles. Designers need to manage the design, prototype, and tests of their latest systems in a virtual environment.

Using iQBus, engineers begin a new design by investigating system architectures and defining major modules, their positions in the system, and their connectivity. The topology analysis leads to requirements for the subsystem design. Components are then defined and connected by wires (2-D/3-D cable drawings). A virtual verification using simulation follows every revision to check the functionality against specifications and to apply a modification or redesign if the system does not match specifications. Real subsystems then replace virtual subsystems step by step, which requires that a virtual subsystem run in real time to evaluate the system with real hardware-in-the-loop. Finally, the designer must document the system and send it to manufacturing.

Building a virtual prototype of the design requires "models" to enable the analysis. iQBus offers characterization tools that allow users to create models from available data. Input for model characterization can come from a scanned datasheet, measurement data, or simulation coupled with optimization. A built-in optimizer automatically matches the model performance data to measured values. Moreover, the iQBus comprehensive library contains 30,000 parts (models) spanning different engineering disciplines (e.g., motors to microprocessors).

Designers can implement a microprocessor and its software several ways. One way includes using a control algorithm from the control library as a behavior model. Implementation also can occur by importing a foreign-function, C-Code call from a design tool such as Mathworks' Simulink/Stateflow, or using an instruction-set microprocessor model with the target code running on it.

- Frank Bokulich

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