Evaluation of a CIDI Pre-Transmission Parallel Hybrid Drivetrain with CVT, Grzegorz PÅ‚uciennik, Mechanika ...
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Evaluation of a CIDI Pre-Transmission Parallel Hybrid Drivetrain with
CVT
Maxime Pasquier, Mike Duoba, Keith Hardy, Aymeric Rousseau, and Dave Shimcoski
ABSTRACT
Argonne National Laboratory (ANL) is the lead laboratory for hardware-in-the-loop (HIL) testing and
technology validation for the U.S. Department of Energy’s Office of Advanced Automotive
Technologies (DOE OAAT). In this role, ANL contributes to DOE OAAT goals by setting technical
targets and evaluating new technologies in a vehicle systems context, with a focus on hybrid electric
vehicle (HEV) technology.
ANL employs a unique integrated process based on powerful simulation tools and experimental
facilities to perform system-level tests quickly and cost-
effectively. This approach allows ANL researchers to
simulate a vehicle system, design an optimal control strategy,
and then apply it to the real components and subsystems
being evaluated. The objective is to better understand 1)
component/subsystem performance and control requirements
in a simulated vehicle environment and 2) the effect of
control on emissions and efficiency.
This process has been applied to the evaluation of a hybrid
powertrain consisting of a Compression-Ignition Direct-
Injection (CIDI) engine, an electric traction motor, and a
Continuously Variable Transmission (CVT). This paper
describes the testing methodology, the building of the
powertrain, the control strategy used, and the analysis of
results.
Copyright 2002 EVS19
Keywords:
Parallel HEV (hybrid electric vehicle), diesel engine, CVT (continuous variable
transmission), simulation, control system.
1. Introduction
Along with U.S. automakers and the other U.S. Department of Energy (DOE) laboratories, Argonne’s
Center for Transportation Research (CTR) plays a prominent role in the research and development
efforts for FreedomCAR, a partnership between DOE and USCAR (DaimlerChrysler, Ford, and
General Motors). In this initiative, DOE has directed CTR to assess advanced vehicle and engine
technologies as well as validate DOE-sponsored propulsion components in the Advanced Powertrain
Research Facility (APRF). The APRF can test components, subsystems or vehicles utilizing electric
component dynamometers or 2/4WD chassis dynamometers. The primary resource applied to this
effort is the HIL test cell, consisting of a pre-transmission parallel hybrid powertrain with a
continuously variable transmission (CVT) and a compression-ignition direct-injection (CIDI) engine in
an emulated vehicle environment. The intent of this project is to demonstrate reductions in diesel
engine emissions by using a system approach.
The ANL-developed PSAT-PRO

, a control code based on PSAT

models, was used to automatically
command and control all of the components of the powertrain, as well as the dynamometer and the
dynamic brakes. The hybrid powertrain is controlled on a test stand by emulating vehicle behavior
with a dynamometer, brake, and inertia flywheels. The overall objectives are to quantify emissions
benefits of hybridization and optimize control strategy for emissions reduction.
2. Unique Integrated Process
ANL’s system analysis program provides an unsurpassed combination of capabilities, expertise, and
facilities. CTR offers technologically advanced tools and resources, such as powerful transient vehicle
models linked with test stands to emulate virtual vehicles and provide HIL testing of propulsion
components and subsystems. The tightly integrated process reduces wasted effort in progressing from
modeling and simulation to implementation, testing, and validation by removing the barriers
associated with communication, data transfer, unnecessary code generation, or software changes.
The modeling and controls effort is designed to bridge the modeling and experimental hardware
testing programs. By using the ANL-developed forward-looking HEV modeling software PSAT

,
control strategies can be optimized, translated to PSAT-PRO

and integrated in a micro-controller for
hardware control [1]. PSAT-PRO

, designed for use in the APRF, is a Matlab
©
-based program that
uses dSPACE
©
prototyper to link PSAT

control strategy and real hardware control. This direct
connection between modeling and simulation software, control software, and the APRF offers the
opportunity to streamline technology development through continual feedback and refinement [2].
Figure 1: PSAT-PRO
©
integration
The APRF is a flexible, controlled test environment that can be used to assess any powertrain
technology, including engines, fuel cells, electric drives, and energy storage. State-of-the-art
performance and emissions measurement equipment (listed below) is available to all component and
vehicle test cells to support model development, HIL, and technology validation.
• Light- and heavy-duty dynamometers • Ultra-fast (<5 ms) HC and NO
x
measurement
• 2WD and 4WD chassis dynamometers • Fast (10 Hz) direct fuel measurement
• Battery/fuel cell emulator (150 kW) • Fast (10 Hz) particulate measurement;
• Precision-controlled environment • unique laser-induced incandescence (LII)
• SULEV emissions measurement capability • Mini-dilution PM measurement
•
Low-emissions raw emissions bench
• Scanning mobility particle sizer
3.
CIDI Pre-Transmission parallel hybrid drivetrain
Figure 2: Layout of Major Components of Hybrid Drivetrain
A Compression-Ignition Direct-Injection (CIDI) Engine from a Mercedes-Benz A170 CDI vehicle was
removed from a research vehicle and prepared for testing as part of this HEV powertrain
configuration.
Figure 3: CIDI 1.7L engine
The transmission is a modified Nissan CK-2 CVT, which uses a Van Doorne push- type belt that is
commercially available in several Japanese production vehicles. Mechanical and electrical
modifications were made to the CVT, both internal and external to the transmission. In stock trim, an
off-board transmission control unit that controls torque converter lock-up, CVT ratio, and hydraulic
pressure accompanies the CVT.
Figure 3:
1.7l CIDI Engine
This was eliminated and all CVT control is done with the PSAT-PRO

computer; additional hardware
has been added to support this approach. The other main modification to the CVT was removal of the
internal high-pressure hydraulic pump. It was replaced with an off-board pump. By fitting an external
pump, much higher power transmission efficiencies can be realized.
Figure 4: Modified Nissan CVT
A hydraulic friction brake was designed to provide the retarding torque that a vehicle would need
during an aggressive driving cycle. Two calipers are used on the same disk so that no radial force is
applied to the rotating shaft and the calipers act as a couple. The calipers, disk, and master cylinder are
automotive aftermarket units, typically used in racing applications. The control of the system is
provided by PSAT-PRO

.
To translate this to a brake pressure (and resulting torque), an air control system was designed to
operate the hydraulic automotive master cylinder. A high-precision pneumatic regulating valve takes
the analog command from the PSAT-PRO

computer and provides a proportional air pressure output.
The output pressure then enters a pneumatic cylinder that provides the mechanical force to the
automotive hydraulic master cylinder via a linkage. The hydraulic pressure from the master cylinder
actuates the calipers.
Dual piston
brake
calipers
Master brake cylinder
Piston linkage
High-precision
pneumatic regulating
valve
Pneumatic
cylinder
Figure 5: Disc Brake and Controller
The flywheels were sized to provide the inertia required for the mass of the simulated vehicle.
Rotating arbor and
inertia flywheel
Stationary, optional
flywheels can be
attached to arbor if
additional inertia is
required
Figure 6: Inertia flywheels
The motor, a 45-kW DC brushless permanent magnet traction drive system from Unique Mobility
(UQM), introduces the electrical torque into the powertrain by the use of a flat-toothed belt. The belt
is a Woods QT Power Chain specifically made for high-torque applications. For greater accuracy in
simulating the components in an actual vehicle, the components were designed to keep the inertia to a
minimum.
Figure 7: DC brushless permanent magnet electric motor
4. Control System description
The hybrid powertrain is controlled with PSAT-PRO
©
. Specifically, the computer-based PSAT-PRO
©
vehicle controller controls the torque of the powertrain to track a simulated vehicle speed profile. The
speed of the transmission output shaft (corresponding to the wheels) is measured. This measured
speed feeds the vehicle model to determine the vehicle losses in these conditions. To simulate the
torque losses that would be produced in reality by the vehicle’s aerodynamics, the calculated vehicle
losses are sent to the dynamometer as a torque command. The powertrain control computer is shown
in Figure 8 and the overall concept is shown in Figure 9.
Figure 8: HIL hybrid powertrain control computer using PSAT-PRO
©
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