Alexander Ezzat

UBC Solar is a student team focused on the design and manufacturing of solar-powered race cars. One of the top goals of the team is to promote clean energy and sustainable automotive solutions. UBC Solar consists of over 60 members spread across 8 technical subteams and a marketing team.

Alex used to be the team caption (2019 – 2021) and is now serving the team as a technical advisor. Powersim is sponsoring the team for several years to build their solar cars to compete at the American Solar Challenge.

” I very much liked that PSIM was fast and easy to use. I was concerned about having to wait hours for results but it was great being able to run simulations in seconds. It made it very easy to do quick iterations. The template for this exact project was also incredibly helpful and made it easy for us to adapt the model to our needs (e.g. bus capacitors) and not get stuck on the learning curve. We also reached out to Albert Dunford for some technical help early on and he was extremely helpful and answered a lot of our basic questions. Overall, excellent experience with very few setbacks.”

“PSIM’s sponsorship did wonders in helping us develop the first revision of our team’s custom BLDC motor controller. This kind of project is rarely taken on by undergraduate design teams so the fact that we have a working prototype is an amazing feat in and of itself.

Our solar car currently uses an NGM in-hub BLDC motor that operates at around 3.75kW nominally. We have been using a Tritium Wavesculptor 20 motor controller to date. However, this controller is heavy and quite expensive to repair when it breaks. Our main motivation for taking on this project was to begin the development of a custom controller that would help us get more hands-on with the controller – better understanding, easier maintenance, improved upgradeability, etc.

Due to COVID and being stuck online/inside, we were not able to develop the controller using the solar car’s actual motor. Instead, my capstone team and I (4 members total, 5th year Engineering Physics at UBC) purchased a small 500W motor that we could run off of a benchtop power supply. However, we designed the controller assuming the high-power spec and parameters, and just scaled down a few hardware components at the very end.

PSIM was particularly critical for two steps of the process:

• Control system parameters: The controller uses FOC (Field-Oriented Control) to ensure that it always operates at maximum efficiency. Implementing this control algorithm is extremely complex. Lucky for us, ST Microelectronics has an open-source library for implementing FOC. This library requires pre-determined parameters for operating properly (cutoff frequency and bandwidth for 2 control loops, speed, and torque/current). To determine these parameters, we simulated the entire control algorithm in PSIM to observe the response of the motor to worst-case speed and torque step inputs.
• DC bus capacitors: When designing a DC-AC inverter, it is critical to size the DC bus capacitors appropriately to handle the high-frequency currents required by the motor. We determined the requirement for our setup by simulating the detailed hardware components during motor operation and various speeds/torques and observing the currents through the capacitors. With PSIM, we were able to optimize for cost and volume of the DC link capacitors.

The PSIM simulations were among our first steps and helped us propel the project forward. The provided templates by PSIM also made this super straightforward. Since then, we have built our first PCBs and fully tested the hardware, with incredible success. At this time, custom firmware design is ongoing in preparation for vehicle implementation.”

To follow the progress of the team’s work check out their website or follow them on Instagram @ubcsolar.