Thermal Modeling and Simulation for Electric Vehicle Thermal Management System

Developed a comprehensive 1D thermal model to simulate the transient thermal behavior of an electric vehicle's thermal management system under varying operating conditions. The system integrates battery cooling, motor cooling, and cabin heating/cooling functionalities through a heat pump cycle. The model considered heat generation from the battery pack, motor losses, cabin thermal loads (including solar radiation, passenger metabolic heat, and heat transfer through vehicle surfaces), and heat transfer mechanisms across various components.

Vehicle Model - Tesla Model 3

Most of the calculations and assumptions in the thermal model were based on the specifications and characteristics of the Tesla Model 3 electric vehicle. This includes:

Battery pack capacity (55 kWh) and configuration (96 cells in series, 31 cells in parallel)
Average power consumption (1 kWh per 6 km) and current draw (15A) based on the UDDS drive cycle
Vehicle dimensions and surface areas for heat transfer calculations
Typical coolant flow rate (25 LPM) based on Tesla's thermal management system

Objectives:

Propose and design a thermal management system architecture for an electric vehicle, capable of handling battery and motor cooling, as well as cabin heating and cooling requirements.
Develop a simplified 1D thermal model to simulate the system's dynamic thermal behavior under different environmental conditions and operating scenarios.
Calculate heat generation from the battery pack based on internal resistance, current draw, and pack configuration (series/parallel cells).
Estimate motor losses based on efficiency and power consumption data.
Determine cabin thermal loads by considering solar radiation (direct and diffuse), passenger metabolic heat, and heat transfer through metal and glass surfaces.
Calculate heat transfer parameters and convective coefficients for various components, including the battery pack coolant loops, radiator, cabin condenser, and refrigerant cycle.
Implement the thermal model in MATLAB and simulate the transient temperature response of the cabin under winter and summer conditions.
Analyze the model's performance and validate the system's ability to maintain the cabin within the desired comfort temperature range.

METHOD -

The project methodology involved an in-depth study of the Tesla Model 3's specifications, including its battery pack configuration, motor characteristics, and vehicle dimensions. These data served as the foundation for subsequent calculations and simulations. Detailed analyses were performed to quantify heat generation from the battery pack using internal resistance, current draw, and pack configuration (series/parallel cells). Motor losses were estimated based on assumed efficiency ranges for electric vehicle motors and power consumption data from driving cycles.

Cabin thermal loads were meticulously determined by considering various factors, such as direct and diffuse solar radiation (using data from California's sunny climate), passenger metabolic heat generation, and heat transfer through the vehicle's metal and glass surfaces. These calculations provided a comprehensive understanding of the thermal environment within the cabin.

With the heat sources and loads quantified, a sophisticated 1D transient thermal model was developed using MATLAB. This model incorporated heat transfer equations and energy balances to simulate the system's dynamic thermal behavior. Detailed calculations were performed to determine heat transfer parameters, such as areas and convective coefficients, for critical components like battery coolant loops, the radiator, and the cabin condenser.

Using this comprehensive model, transient temperature simulations were conducted under contrasting winter (starting from 10°C) and summer (starting from 40°C) conditions. The model's performance was evaluated based on its ability to maintain the cabin temperature within the desired comfort range (above 25°C in winter and below 18°C in summer).

Fig.- 1D Thermal Model Developed for Summer Conditions

Fig.- 1D Thermal Model Developed for Winter Conditions

Outcomes:

Developed a comprehensive 1D transient thermal model for the integrated thermal management system of the Tesla Model 3 electric vehicle.
Successfully simulated the cabin temperature response under two contrasting scenarios:
1. Winter conditions: Starting from an initial cabin temperature of 10°C, the model achieved and maintained a comfortable cabin temperature above 25°C.
2. Summer conditions: Starting from an initial cabin temperature of 40°C, the model reduced and maintained the cabin temperature below 18°C, ensuring passenger comfort.
Gained extensive insights into the complex thermal behavior and heat transfer mechanisms within an electric vehicle, including:
1. Heat generation from the battery pack is based on internal resistance, current draw, and pack configuration.
2. Motor losses estimated from efficiency data and power consumption rates.
3. Cabin thermal loads account for solar radiation (direct and diffuse), passenger metabolic heat, and heat transfer through vehicle surfaces.
Demonstrated proficiency in thermal modeling, heat transfer calculations, and numerical simulations using MATLAB.
Performed detailed calculations to determine heat transfer parameters, such as areas and convective coefficients, for critical components like battery coolant loops, radiator, and cabin condenser.
Showcased the ability to integrate knowledge from various engineering domains, including thermodynamics, fluid mechanics, and solar radiation analysis, to develop practical solutions for complex thermal management challenges in electric vehicles.
Acquired expertise in designing thermal systems, performing multidisciplinary engineering calculations, implementing numerical simulations, and analyzing system performance – skills highly valued in the electric vehicle industry.

Project Report -

Report_Ayushman.pdf

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