HEV Vehicle Modeling

The goal of this project was to analyze and model an HEV vehicle for UDDS and HWY cycles and compare the results from the actual data. The car selected was the Honda Accord.

Powertrain Structure

To develop the vehicle model an individual analysis of the different components was performed. The systems involved in the HEV were:

Motor
Battery
Engine

From the test data obtained from EPA's repository the speeds and times were studied and used for the individual and main analysis.

Engine Model

Using the input signals from the test data: Engine speed CAN, Engine Calculated Torque and Engine Fuel Flow the results for Engine Efficiency and Losses were computed.

The engine efficiency was η = 39.02%

Battery Model

In this case the input signals were the Battery Hioki Voltage and Current so the normal voltage and battery resistance were calculated. The results for the model were:

Vo= 256.45 V
R = 0.0983 Ω

Motor Model

Using the Motor Torque CAN and Motor Speed CAN the motor efficiency was obtained. The result was η = 94.12%

Control Structure

As many HEV the hardest part of the design was the control structure, how the vehicle performs depending on the speed, acceleration, braking,...

The test data already includes these schematics but the mission was to recreate these controls only from data. The wheel power was used to perform the analysis and stablish the correlations between components.

UDDS Comparison

The graphs below show the urban cycle comparison for the motor and engine models with the real data. As it can be seen the motor performance is very similar to the real data, the engine was close at some points but not all the peaks considered in the cycle were correct.

HWY Comparison

The graphs below show the highway cycle comparison for the motor and engine models with the real data. In this case the peaks were simulated correctly but the amplitude was hard to measure and consider. Since the whole model involved 3 different components it was complex to extract the specific controls from the data.

Results

Although the simulation was not perfectly accurate the results obtained were very positive in performance. Almost all of the parameters considered were well modeled with a error margin of approximately 3% which is great considering we didn't have the control structure.

Overall this was a great project to understand the basic physics behind an HEV car and how the modelling of these systems is a complex duty but can recreate valid results

Page updated

Google Sites

Report abuse