Control Design of a Hardware in the Loop Set-Up
Mathieu Dutré
Supervisor(s): Prof. Dr. Ir. Mia Loccufier, Prof. Dr. Ir. Rene Boel (EESA - Universtiy of Ghent)
Dr. Ir. Jan Anthonis and Ir. Stijn De Bruyne (LMS International)
Abstract— This article tries to extend the limits of automotive design by
proposing a new manner to develop new components. Introducing Hardware
in the Loop testing as a new way to reduce development time and development
costs.
Keywords—control technique, induction motors, Hardware in the Loop testing, indirect field orientation, continious variabel transmission
I. I NTRODUCTION
A. What is Hardware in the Loop testing?
I
N automotive, there is a constant push to reduce the development
time of a vehicle. Therefore components should be tested under
the most realistic conditions even when there is no prototype available. This is performed by a so called hybrid Hardware in the Loop
(hy-HiL) simulation.
Hy-HiL starts from a model of the system, where the component
that needs to be tested is removed from the model. The remaining part of the model interacts with the real physical component
through actuators and sensors. In theory, actuators should act like
the removed component model, i.e. following exactly the computed outputs of the simulation model. Sensors should send faultless measurements back to the software model.[1]
Fig. 2. Hardware in the Loop Set-up
The actuators, induction motors, however have their own dynamics so that the calculated control signals in software are not the
same as those achieved by the actuator and forwarded to the continiously variable transmission. In other words, the actuators should
act like the software model. To realize this, advanced motor controllers will be needed in such a way that the influence of actuator
dynamics is reduced to a minimum. Using advanced controltechniques, it will be able to create ideal torque and speed regulated
induction motors.
II. D ESIGN OF A H IGH -P ERFORMANCE M OTOR C ONTROLLER
A. Concept of Field Oriented Control
The use of AC-motors in applications that require a high level of
dynamism asks for an new apporach: Field Oriented Control [3].
Fig. 3. Basic FOC Speed Control Scheme for AC Motor Drives [3]
Fig. 1. Transition from theoretical to practical Hardware in the Loop Testing
In practice however, actuators have their own dynamics that affect the control signals to the physical component. Therefore, a
controller should be designed to reduce the negative effects of the
actuator (figure 1). The design of feedback controllers always involves a risk, especially when the system turns unstable. that is
why a first step in the HIL-process is a feasibility study in a simulation environment. [2]
B. Problems with practical Hardware in the Loop Set-Up
Hardware in the Loop modeling is applied to a CVT test set-up
at LMS. The test set-up consists of 2 induction motors that take
over the duties of an internal combustion engine and a driving axle.
The test set-up will mimic the behaviour of a vehicle powertrain
and may be used to test gearboxes (figure 2).
The goal of FOC is to control an AC motor as a DC motor which
means a complete decoupling of torque and flux. Field Oriented
Control requires the transfer of 3-phase (a,b,c) reference system to
a 2-phase dynamic reference system (d,q). Torque-and flux values
in this reference system may be regulated by adjustments in q-axis,
or d-axis current. The basic FOC Speed Control Scheme is shown
in figure 3.
The FOC control strategy maintains the amplitude of the rotor
flux linkage ψ at a fixed value, except for field-weakening operation, and only modifies a torque-producing current component
in order to control the torque of the ac motor. When considering a complete decoupling of torque and flux, a linear relation between torque Tem and torque producing current iq is achieved so
the torque generated by the motor can be controlled by just controlling the q-axis current. The electromagnetic torque in the ac
machine can be expressed as
Tem = k.ψ.iq
(1)
Torques Input Shaft CVT
Revs Input Shaft CVT
200
150
3000
TLogged Data
TRealised in Simulation
100
50
0
−50
−100
0
NLogged Data
2500
Revs [RPM]
The orgininal simulation model of a hybrid driveline was modified to investigate the actuator behaviour in the real HIL set-up.
The original hybrid driveline model (figure 4) consists of 2 main
parts: the mechanical components, including the internal combustion engine, gearbox and other driveline components, is modeled
in AMESim, the LMS software package.
The overarching rule-based controller is designed in MatlabSimulink. This rule-based controller determines, depending on the
sensor signals from the vehicle model, the optimal operating mode
(pure electric driving, regenerative braking, ...) of the sources used
for propulsion (ICE/EM).
NRealised in Simulation
2000
1500
1000
500
0
50
100
150
200
250
300
−500
0
350
50
100
150
200
250
300
350
Time [s]
Time [s]
Torques Output Shaft CVT
Revs Output Shaft CVT
200
TLogged Data
1000
TRealised in Simulation
500
0
−500
0
50
100
150
200
250
300
350
0
−200
Revs [TPM]
III. HIL SIMULATION MODEL
In the original hybrid driveline model, the torques and speeds on
the primary and secondary CVT shaft were logged. These logged
data formed the input of our torque and speed regulated controllers.
The overall simulation results are shown in figure 6. A more accurate picture of the simulation data can be seen in figure 7. From
the simulation results can be concluded that the electric motors can
follow perfectly their setpoints.
Remark: TLogged Data / NLogged Data are the logged torque
and speed measures.
TRealised in Simulation / NRealised in Simulation represents
the torques and speeds as achieved in simulation by the actuators
Torque [Nm]
Field Oriented Control can be used to follow a speed reference
or a torque reference. In speed control mode, a reference speed
∗
forms the input of the control scheme. The torque reference Tem
is calculated by a speed controller. Rotor flux can be controlled directly by controlling the d-axis current. This scheme is represented
∗
in figure 3. In torque control mode, the torque reference Tem
forms
the input of the control scheme. It is simply a speed regulated FOC
control scheme without the speed control loop.
IV. VALIDATION OF THE D ESIGNED M OTOR C ONTROLLERS
Torque [Nm]
B. Speed Regulated and Torque Regulated FOC
−400
−600
−800
NLogged Data
−1000
NRealised in Simulation
−1200
0
50
100
Time [s]
150
200
250
300
350
Time [s]
Fig. 6. Comparison between theoretical and modified HIL simulation model
Torques Input Shaft CVT
Revs Input Shaft CVT
100
1510
T
Realised in Simulation
Revs [RPM]
Fig. 4. Original AMESim-Simulink Hybrid Driveline Simulation Model
Torque [Nm]
90
1520
TLogged Data
80
70
60
50
N
Realised in Simulation
1500
1490
1480
1470
224.5
225
225.5
1460
224
226
224.5
Time [s]
N
Logged Data
TRealised in Simulation
80
224.5
226
Revs Output Shaft CVT
100
60
224
225.5
−910
TLogged Data
Revs [TPM]
120
225
Time [s]
Torques Output Shaft CVT
140
Torque [Nm]
The original model is adjusted to simulate the impact of the actuators on the real HIL set-up. Just before and after the CVT transmission 2 electric motors were added (figure 5). The torque regulated electric motor, on the ingoing CVT shaft, should pass through
the combustion engine torque faultless to achieve an error-free transition between the theoretical and practical HIL set-up as seen in
figure 1. On the outgoing CVT shaft, the speed controlled electric
motor has to realize the desired axle speed.
When the torque regulated motor and the speed regulated motor
follow their torque- or speed setpoint faultless, our main purpose is
completed. The electric motors, the actuators, will not charge the
HIL set-up with additional dynamics.
40
224
NLogged Data
225
225.5
226
NRealised in Simulation
−920
−930
−940
−950
224
Time [s]
224.5
225
225.5
226
Time [s]
Fig. 7. Comparison between original and modified HIL simulation model
V. C ONCLUSION
The use of appropriate motor controllers reduces the influence of
actuator dynamics into a minimum. The regulated electrical motors
act like ideal velocity and torque inputs for the physical component.
Physical components can therefore be tested in realistic conditions
without a prototype available using hardware-in the loop configurations. Hardware in the Loop can be used to shorten the development time and cut the development costs of a new product.
R EFERENCES
Fig. 5. Adapted AMESim-Simulink Hybrid Driveline Simulation Model (Actuators
Implemented)
[1] Jan Anthonis, Marco Gubitosa, Nicolas Albarello, Peter Maes, Bart Peeters,
Herman Van der Auweraer Mechatronic Optimization in Intelligent Vehicles:
Application to Active and Passive Dampers, LMS Interantional, 2009.
[2] Jan Anthonis, Mia Loccufier, Master these Proposal: Control Design of Hardware in the Loop Set-up, Department Electrical Energy, Systems and Automation (EESA), University of Ghent, Mai 2009.
[3] Gerd Terörde, Electrical Drives and Control Techniques, Published by ACCO
Uitgeverij,2004.