Research Papers: Gas Turbines: Controls, Diagnostics, and Instrumentation

Optimal Transient Control Trajectories in Diesel–Electric Systems—Part I: Modeling, Problem Formulation, and Engine Properties

[+] Author and Article Information
Martin Sivertsson

Division of Vehicular Systems,
Department of Electrical Engineering,
Linköping University,
Linköping SE-581 83, Sweden
e-mail: marsi@isy.liu.se

Lars Eriksson

Division of Vehicular Systems,
Department of Electrical Engineering,
Linköping University,
Linköping SE-581 83, Sweden
e-mail: larer@isy.liu.se

1Corresponding author.

Contributed by the Controls, Diagnostics and Instrumentation Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received May 15, 2014; final manuscript received June 3, 2014; published online September 16, 2014. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(2), 021601 (Sep 16, 2014) (11 pages) Paper No: GTP-14-1238; doi: 10.1115/1.4028359 History: Received May 15, 2014; Revised June 03, 2014

A nonlinear four state-three input mean value engine model (MVEM), incorporating the important turbocharger dynamics, is used to study optimal control of a diesel–electric powertrain during transients. The optimization is conducted for the two criteria, minimum time and fuel, where both engine speed and engine power are considered free variables in the optimization. First, steps from idle to a target power are studied and for steps to higher powers the controls for both criteria follow a similar structure, dictated by the maximum torque line and the smoke-limiter. The end operating point, and how it is approached is, however, different. Then, the power transients are extended to driving missions, defined as, that a certain power has to be met as well as a certain energy has to be produced. This is done both with fixed output profiles and with the output power being a free variable. The time optimal control follows the fixed output profile even when the output power is free. These solutions are found to be almost fuel optimal despite being substantially faster than the minimum fuel solution with variable output power. The discussed control strategies are also seen to hold for sequences of power and energy steps.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Fig. 2

Structure of the MVEM. The modeled components as well as the connection between them.

Grahic Jump Location
Fig. 1

BAE systems TorqE diesel–electric powertrain

Grahic Jump Location
Fig. 3

Cardan power for a step from idle measured on one of the considered applications

Grahic Jump Location
Fig. 4

Generator actuation for different criteria. Circles mark the end points.

Grahic Jump Location
Fig. 5

Time and fuel optimal solutions to different load transients. The time and fuel optimal transients have similar structures but differ in how they meet the end constraints. Since several trajectories are plotted, the smoke-limit for unloaded engine acceleration is clearly visible.

Grahic Jump Location
Fig. 6

Time and fuel optimal solutions to a load transient from idle to 170 kW

Grahic Jump Location
Fig. 7

Top: kinetic energy in the engine as well as the total kinetic energy in the system at time T. Bottom: kinetic energy in the turbocharger at time T.

Grahic Jump Location
Fig. 8

Change in time and consumption as a function of Preq

Grahic Jump Location
Fig. 9

Comparison between fuel optimal transients and transients to the fuel optimal operating point. * denotes the fuel optimal operating point.

Grahic Jump Location
Fig. 10

Two trajectories that are both time optimal, but the fuel consumptions differ by 10.6%. For higher Ereq, the minimum time solution is not unique.

Grahic Jump Location
Fig. 11

Minimum time transients from idle to Preq = [100 150 200] kW for different Ereq. The characteristics of the solution are independent of both Ereq and Preq.

Grahic Jump Location
Fig. 12

State and control trajectories for minT,Preq = 170 kW for different Ereq

Grahic Jump Location
Fig. 13

Minimum fuel transients from idle to Preq = [100 150 200] kW for different Ereq

Grahic Jump Location
Fig. 14

State and control trajectories for min mf,Preq = 170 kW for different Ereq

Grahic Jump Location
Fig. 15

Torque versus engine speed for minmf/T one and two-phase solutions as well as for a step in power without requirements on produced energy

Grahic Jump Location
Fig. 16

Engine speed and torque trajectories for minT4-phase and minmf4-phase. The solutions are similar despite different criteria.

Grahic Jump Location
Fig. 17

State and control trajectories for min T4-phase and min mf4-phase




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In