7172MAA Advanced Propulsion Systems Resit CW Assignment Brief CU | 2024-25

Contents:

• Assignment Information
• Assignment Task
• Marking and Feedback
• Assessed Module Learning Outcomes
• Assignment Support and Academic Integrity
• Assessment Marking Criteria

Assignment Credit: 15 credits

Percentage Grade (Applied Core Assessment). You will be provided with an overall grade between 0% and 100%. To pass the assignment you must achieve a grade of 40% or above.

Assignment Task

In this coursework, you are required, individually, to design, analyse and simulate a Battery Electric Vehicle (BEV) powertrain using MATLAB/Simulink. Firstly, you should apply your knowledge to size and select proper components of the vehicle. Subsequently, develop a model for the powertrain system that enables you to design the controllers and evaluate your design. Finally, evaluate your design by comparing the resulting performance indices with the expected values. The characteristics of the vehicle and the desired targets of powertrain systems are different for each Student.

The following documents/files are provided on the Aula assessment tab:

• Catalogue of electric machines with different rated powers and characteristics.
• Typical efficiency map for electric machines.
• Specification and characteristics of Panasonic NCR18650GA battery cell.
• WLTP (Class 3) drive cycle.

Model based design and verification of a Battery Electric Vehicle (BEV) powertrain system:

You are asked to design a Battery Electric Vehicle (BEV) powertrain system using the model- based design (MBD) approach. Part of the design relies on a driving cycle; for those parts, you should design the powertrain system to meet the WLTP (Class 3) requirements.
Initially, deploy a MBD approach to size the vehicle's main components and ensure the desired powertrain targets for each vehicle (0-100 km/h acceleration of the vehicle, maximum speed and pure electric range) are met. You should apply an iterative MBD method to find the final design values.

In the next stage, you should develop the model for the powertrain system based on the size of the components you found in the previous stage. Using this model, design a controller and validate your design to determine if the performance criteria are satisfied. Then evaluate your design using MBD.

In this brief: MD is Motor-Drive and VD is Vehicle Dynamics.
Assignment Sections and Mark Distribution

1. Powertrain System Design and Component Sizing (30%)
   Design and justify the BEV’s key subsystems:

1.1 Vehicle Parameter Customisation

The Battery Electric Vehicle (BEV) powertrain is composed of an electric machine to propel the vehicle. The Battery is used to produce electricity to powers the motor directly. Additionally, regenerative brake can be achieved through the motor connected to the tires. You should size different components, such as the motor drive and battery. The sizing is done based on primitive calculation on each student individually to fulfill the requirements plus a feedforward power/energy modelling that uses the specific driving cycle to calculate power and torque based on the derivative of speed.

Calculate the mass, drag coefficient, rolling resistance, and acceleration target using your Student ID:

• Mass = 1100 kg + last 3 digits of your SID
• Drag coefficient = 0.27 + (last 2 digits of SID × 0.0005)
• Rolling resistance = 0.015 + (last 2 digits of SID × 0.0001)
• Acceleration (0–100 km/h) = 7 s + (last 2 digits of SID × 0.03)
• Target Range = 250 km + last 2 digits of SID
• Tyre size = 205/65 R15

1.2 Forward-Step Power Modelling (10%)

Use a forward power model to calculate the required power and energy from the powertrain based on the driving cycle.
The report should contain the following:

• The forward-step Simulink model.
• A graph showing the instantaneous driving power versus time.
• The net energy, the regenerative energy, and the tractive energy (all in kWh) through the driving cycle
• The average tractive power and the maximum tractive power demand

1.3 Motor Sizing and Transmission Design (10%)

In this section, you select an appropriate electric machine for traction from the given catalogue. The characteristics of the electric machine are given in the catalogue and the efficiency map of PMSM motors in the excel sheet provided.

Calculate the required rating power for motor drive based on the required acceleration time, select a proper transmission ratio – gearbox & final drive – to connect the electric machine to the wheels. You can select a single motor connected to the drivetrain, two motors connected to one axle, or four different motors to connect to each wheel individually.

The motor selection is an iterative method, which means that you should predict an initial power for the motors and select a motor based on that and make sure it satisfies the requirements; if it is not meeting the needs, you should change your prediction and do it until the predicted value can fulfil all the requirements (without exceeding them by more than 15%).

The design is usually verified by comparing the power requirements of feed-forward modelling with the values you have found from primitive design calculation.

For the selected motor drive, your report should comprise the following:

1. Calculation of the required power for the motor drive and an appropriate gear ratio.
2. Report the type of electric machine, the rated power, the rated torque, the maximum speed, the required DC voltage, and the maximum current based on the attached electric machine catalogue.
3. Report the gear ratio you have selected to connect the motor to the tires.
4. Report what type of motor configuration you finally opted for (single motor, two motors or four motors).
5. Calculate the vehicle maximum gradeability on dry and wet asphalt.

1.4 Battery Pack Design (10%)

Design the battery pack based on the required DC voltage and power requirements of the selected motor-drive(s) and the desired range in pure electric mode driving. You must only use the cell “Panasonic NCR18650GA” for the battery pack design. The final design of the battery pack should comprise the following items:

• The energy capacity of the battery pack in kWh.
• The capacity of the whole battery in Ah.
• The number of battery cells in parallel and series configuration.
• The nominal voltage of the battery pack (based on the requirement from the electric traction machine).

Figure 1 Flow diagram

Submission Instructions:

• The report must be in Word or PDF format.
• you will need to submit the Simulink model that will be used for reference purposes only to verify the data in the report (Handin link).
• Both submission links have the same deadline.
• Filename must follow format: 7172MAA_YourSID_Report.pdf and 7172MAA_YourSID_Model.slx. Missing model files may result in deduction.

Format (5%)

The report should have appropriate formatting. Your report should comply with technical report standards. The format criteria include the following:

• Page numbers, table of contents and appropriate heading for sections and subsections.
• Clear photos, images, and charts. The data on the graphs should be easily readable.
• Numbers and captions for all figures and tables. These items should be referenced in your report.
• The size and type of font should be appropriate for reports. (Usually, a font size of 12 is appropriate.)
• You must reference all sources using Coventry Harvard referencing style. Include a bibliography at the end.

Assessed Module Learning Outcomes

The Learning Outcomes for this module align to the marking criteria which can be found at the end of this brief. Ensure you understand the marking criteria to ensure successful achievement of the assessment task. The following module learning outcomes are assessed in this task:

ILO 3. Calculate the road load and size of the powertrain components based on forward and backward powertrain analysis.
ILO 4. Define the performance indices and fuel/energy consumption characteristics of the vehicles.
ILO 5. Design and verify the advanced electrified propulsion systems using model-based approaches.

Assessment Marking Criteria

Guidance for Course Teams: Assessment criteria should align to the University-level assessment criteria for the relevant level of study. These are available through the Academic Enhancement and Professional Development website. Training on assessment and feedback approaches is available through the Course Booking System.

(Delete if not applicable or replace with different marking criteria)

Important: If the assessment used is a Core (Pass/Fail) assessment then please amend the marking criteria accordingly. Guidance on the use of Core Assessment is available on the Office of Teaching and Learning SharePoint site.