08-05-2012, 11:43 AM
Honda Insight model
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Introduction
The Honda Insight model is developed based on test data, provided by the National Renewable Energy Laboratory, Golden, Colorado, and
Argonne National Laboratory, Illinois. The model aims at describing the control strategy and the characteristics of the Honda Insight
drivetrain.
The following is the base block diagram used in the simulation of the Insight. Here, the control block directly commands the torques required
from the 2 power sources namely the IC engine and the electric motor.
Honda Insight Torque Split Control Strategy (scalable)
The Honda Insight Torque Split control strategy is explained below. This is developed as a result of test data analysis and observation of
component behaviour. This model is scalable, and can be used by the user, to define his own control strategy.
The control strategy block <cs> receives the torque required into the clutch. Based on this value and the vehicle speed, the electric motor
torque contribution is calculated. The remaining torque is demanded from the IC engine. The electric motor torque is decided based on the
following criteria:
When accelerating, based on the torque and rate of acceleration, the electric motor assists the IC Engine, producing around 10 Nm of
torque.
During regeneration,(in reality, when the brake is depressed), the electric motor regens a portion of the negative torque availabe to the
driveline.
At low vehicle speeds, typically below 10 mph, the braking is primarily only the friction brakes.
ADVISOR Help on Honda Insight Model file://C:/Users/TRI_VIET/Documents/MATLAB/ADVISOR2002/docume...
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There is no electric assist in the first gear.
Test data - a basis
Test data from NREL and ANL were analysed to determine the hybrid powertrain characteristics. Shown below, are some characteristics,
based on which the model has been developed.
The following graph depicts the contribution of the electric motor torque based on the total driveline torque. The motor is seen to produce
around 10 Nm of torque during assist.
The Insight IMA does not usually assist the IC Engine during 1st gear. The following graph depicts this phenomenon from test data:
This above plot shows engine rpm, COLOR CODED by gear ratio. (RED-1st gear, GREEN-2nd gear, BLUE-3rd gear, MAGENTA-4th gear,
CYAN-5th gear, BLACK-unknown gear ratio / slip). The electric motor torque is shown by BROWN. It is clearly seen that the motor does
not assist in first gear.
The Insight electric motor regeneration torque depends on the application of the brakes. Also, regeneration reduces, if the vehicle slows down
(typically belolw 10 mph). The following plot depicts this phenomenon from test data.
ADVISOR Help on Honda Insight Model file://C:/Users/TRI_VIET/Documents/MATLAB/ADVISOR2002/docume...
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The following shows the control strategy block in ADVISOR for the Honda Insight.
The following conditions are incorporated in the above model:
In the above block, the torque request is analysed for acceleration (positive torques) or deceleration (negative torques).
The 1st gear condition is checked. Also, at slow speeds, the motor remains inactive.
Since there is no separate alternator in the Insight, the electric motor has to function as the alternator. Thus, the electric motor
generates a small current, based on the power required by the accessories. The battery pack supplies the electrical accessory loads
when the motor assists the engine.
The clutch has to be engaged for the electric motor to regenerate some of the energy from braking.
The battery SoC is checked, since it affects the operation of the motor at low and high ranges of SoC.
The electric motor torque is decided based on the above criteria and the remaining torque is requested from the IC engine. Since the motor
and the IC engine are connected to the same shaft, the controlled IC engine speed is requested from the electric motor also.