How to Perform Battery Electric Vehicle Range Testing Using Simulation

Streamlining BEV Drive Cycles 

Welcome to the second blog of this two-part series on how simulation platforms such as GT-SUITE can streamline the various drive cycles of battery electric vehicles (BEVs) to determine the range and adjustment factors.  

Read part one to learn more about how electric vehicle (EV) range guidelines are currently determined here.  

Building Vehicle Thermal Simulation Models with GT-SUITE 

As noted in part one of this series, the BEV range test procedure outlined in the SAE J1634 standard involves varying test conditions and drive cycles to estimate the final range. Simulation platforms such as GT-SUITE offers engineers the chance to streamline the entire EV range estimation process.

 Using GT-SUITE, the first step in BEV range testing simulation is creating a model of the vehicle thermal management system. The model needs to represent a system-level thermal management circuit of the electric vehicle and contains an integrated model of the following circuits:  

1. High-Temperature (HT) – Cooling circuit 
2. Low-Temperature (LT) – Cooling circuit  
3. Indirect refrigerant circuit 
4. Cabin air circuit 
5. Under-hood air circuit 

This thermal management model is then integrated with a vehicle model, representing the full vehicle and electric powertrain. Multiple control elements are implemented to regulate and adjust inputs to the system components such as the electric pump/fan/compressor, controlled valves, and others. 

GT integrated vehicle thermal model

Automating BEV drive cycles with GT-Automation  

Once the thermal management model is integrated in the vehicle model, there are multiple cycles that need to be simulated to obtain the adjustment factor for a single vehicle configuration. This is where GT-SUITE’s built-in app, GT-Automation, can be leveraged to efficiently evaluate the 5-cycle testing process. 

GT-Automation can be used to create a ProcessMap that allows configuring a workflow of individual processes that are executed in a specific order. It enables users to model the flow of interest to simulate all the required cycles without any manual intervention and extract the relevant energy consumption values into GT’s range calculation Excel tool.

GT process flow for BEV 5-cycle range and adjustment factor

As pointed out in part one of this series, the multi-cycle test (MCT) contains a mid-test constant speed section of varying durations that are dependent on the electric vehicle and its battery pack size. This is another use for GT-Automation to automate the determination of the duration of the mid-test steady state phase in MCT, thereby eliminating the iterative process of selecting the steady-state speed duration for every vehicle configuration.  

Calculating Range with GT’s Excel Tool

Lastly, engineers can use GT’s range calculation Excel tool which includes the required formulas from the SAE J1634 regulation embedded in the cells to estimate the adjustment factor and subsequently compute the label range.

Additionally, GTs range calculation Excel tool helps users manually tweak the energy consumption values in independent drive cycles to quickly understand the impact of different drive cycles and their dependencies on the adjustment factor and range. This further helps optimize control strategies and energy consumption for different vehicle configurations.  

GT range calculation Excel tool

Example Results for Two Vehicle Configurations 

The range of a typical passenger BEV is simulated according to the 2-cycle and 5-cycle methodology outlined in the SAE J1634 standard with different configurations. Utilizing the adjustment factors, both the vehicle configurations gained approximately 5-7% miles in the EPA’s certified range limits, making the 5-cycle testing a favorable option for the manufacturers.  

This, however, does not conclude that the 5-cycle testing option will always improve the adjustment factor and range for any vehicle configuration. It ultimately boils down to the efficiencies of different propulsion components and electrical load requirements at those additional 3 drive cycles that play a vital role in estimating the adjustment factor.  

Learn More About our Battery Simulation Capabilities 

If you’d like to learn more or are interested in trying GT for automating the 5-cycle test process flow for EV adjustment factor and range improvements, speak to a GT battery expert here. 

If you missed part 1 of this series, read more here.  

To learn more about more about battery simulation solutions, check out our battery modeling page and learn more about our hybrid and electric simulation solutions. Also, check our top 15 battery-related topics blogs in this list!