1.0 Introduction

1.1 To the Reader

1.2 Capabilities and intended uses
1.3 Limitations
1.4 System requirements
1.5 How to get additional help
* * * * *

1.1. To the Reader

1.1.1. What is ADVISOR & who might benefit from using it?

    ADVISOR, NREL’s ADvanced VehIcle SimulatOR, is a set of model, data, and script text files for use with Matlab and Simulink.  It is designed for rapid analysis of the performance and fuel economy of conventional, electric, and hybrid vehicles.  ADVISOR also provides a backbone for the detailed simulation and analysis of user defined drivetrain components, a starting point of verified vehicle data and algorithms from which to take full advantage of the modeling flexibility of Simulink and analytic power of MATLAB.

You may benefit from using ADVISOR if you want to:

The models in ADVISOR are:

ADVISOR was preliminarily written and used in November 1994.  Since then, it has been modified as necessary to help manage the US DOE Hybrid Vehicle Propulsion System subcontracts.  Only in January 1998 was a concerted development effort undertaken to clean up and document ADVISOR.

Since then, over 4500 individuals have downloaded one or more versions of ADVISOR, including all of the OEMs and major suppliers.  About 2/3 of the users are from industry and 1/3 from universities.  A short list of major ADVISOR users includes:

1.1.2. How to use this manual

This manual is intended to serve both as a starting point for beginners and as a reference for more experienced users.  New users will benefit most by:

Throughout this manual, Courier font will denote MATLAB commands, and Albertus font will denote ADVISOR variables and filenames.

1.2. Capabilities and intended uses

ADVISOR uses basic physics and measured component performance to model existing or future vehicles.  Its real power lies in the prediction of the performance of vehicles that have not yet been built.  It answers the question “what if we build a car with certain characteristics?”  ADVISOR usually predicts fuel use, tailpipe emissions, acceleration performance, and gradeability.

In general, the user takes two steps:

  1. Define a vehicle using measured or estimated component and overall vehicle data.

  2. Prescribe a speed versus time trace, along with road grade, that the vehicle must follow.

ADVISOR then puts the vehicle through its paces, making sure it meets the cycle to the best of its ability and measuring (or offering the opportunity to measure) just about every torque, speed, voltage, current, and power passed from one component to another.

ADVISOR will allow the user to answer questions like:

By iteratively changing the vehicle definition and/or driving cycle, the user can go on to answer questions such as:

ADVISOR’s GUI and other script files answer many of these questions automatically, while others require some custom programming on the user’s part.

Because ADVISOR is modular, its component models can be relatively easily extended and improved.  For example, an electrochemical model of a battery, complete with diffusion, polarization, and thermal effects, can easily be put into a vehicle to cooperate with a motor model that uses a measured efficiency map.  Of course, developing new, detailed models of drivetrain components (or anything else, for that matter) requires an intimate familiarity with the environment, MATLAB/Simulink.

1.3. Limitations

Primarily for analysis, not design

ADVISOR was developed as an analysis tool, and not originally intended as a detailed design tool.  Its component models are quasi-static, and cannot be used to predict phenomena with a time scale of less than a tenth of a second or so.  Physical vibrations, electric field oscillations and other dynamics cannot be captured using ADVISOR, however recent linkages with other tools such as Saber, Simplorer, and Sinda/Fluint allow a detailed study of these transients in those tools with the vehicle level impacts linked back into ADVISOR.

As an analysis tool, ADVISOR takes the required/desired speed as an input, and determines what drivetrain torques, speeds, and powers would be required to meet that vehicle speed.  Because of this flow of information back through the drivetrain, from tire to axle to gearbox and so on, ADVISOR is what is called a backward-facing vehicle simulation.

Forward-facing vehicle simulations include a model of a driver, who senses the required speed and responds with an accelerator or brake position, to which the drivetrain responds with a torque.  This type of simulation is well suited to the design of control systems, for example, down to the integrated circuit and PC card level—the implementation level.

ADVISOR is well suited to evaluate and, by iterative evaluation, design control logic and energy management strategies.  By this, we mean something like “When the engine torque output is low and the battery state of charge is high, turn off the engine.”  The control logic, with which ADVISOR can work, is about what you want the vehicle to do.  The detailed control system, getting into details of how you would implement this control logic in hardware, is about how to make the vehicle do what you want and is not the original intention of ADVISOR’s application.

Power bus for electric power transfers

In electrical components’ communication with each other, ADVISOR deals in power, and not in voltage and current.  Linkages to other tools, such as Saber and Simplorer let the user work with a voltage bus.

Drive axle is single axle only

The vehicle dynamics calculations required for traction control and the wheel slip model assume that the front axle is the only drive axle.  Simple steps can be taken to correct the weight transfer calculation if you wish to model a rear-drive vehicle, and an example wheel file that accomplishes this is included.  Modeling a four-wheel drive vehicle requires involved Simulink reprogramming.  Please contact NREL if you have such needs.

1.4. System requirements

ADVISOR has been developed and tested in Release 12.1 (MATLAB 6.1 and Simulink 4.1), available from The Mathworks.  The Mathworks software runs on multiple platforms including Macintosh, UNIX, and PCs.  Contact The Mathworks at www.mathworks.com for more information.  ADVISOR files, however,  have been tested using only the PC platform with Windows 2000 (it should still work with NT, and Win 98 as well).  If you have success using other platforms (such as UNIX) we would love to hear about it, but in general we do not support other platforms at this time.

Additional features for users with VisualDOC
Additional features for users with GCTool

1.5. How to get additional help

MATLAB’s on-line help and the MATLAB and Simulink manuals can answer questions about MATLAB and Simulink functions.  Type helpdesk at the MATLAB command prompt.  Additionally, you can type help or helpwin at the MATLAB command prompt.

Descriptions of ADVISOR block diagrams are available by opening the block diagram of interest and double-clicking on the green ‘NOTES’ block in the bottom right or left corner.  Descriptions of ADVISOR component and other files are available from the MATLAB command line by entering help ADVISOR_filename.  Help is also available from within the ADVISOR GUI and subsequent chapters of this documentation.

This manual should get you started doing straightforward vehicle analysis with ADVISOR.  If you have analysis needs beyond what is covered here, please contact NREL directly at  www.ctts.nrel.gov/analysis.
* * * * *

Back to ADVISOR Documentation Contents
Forward to Chapter 2

Last Revised: 4/30/02:KW