UT24 BUCK CONVERTER SHIELD BOARD

The University of Toronto Formula SAE Racing Team (UTFR) is set to compete in a series of races in Michigan, New Hampshire, Czech Republic, and Germany in 2024. Their dedication to innovation and optimal performance is highlighted through the development of the UT24 Buck Converter Shield Board. This board is crucial for enhancing the power regulation of the car's low voltage system and is a key component of UTFR's Rear Controller for their 2025 vehicle.The LMR14050, a 40 V, 5 A step-down regulator with an integrated high-side MOSFET, has been selected for this purpose. It stands out due to its wide input range from 4 V to 40 V, making it suitable for diverse applications, including our own car’s low voltage system, as our low voltage battery varies between 13 and 16.8 volts. 

Buck Shield Board

The regulator's quiescent current is 40 µA in Sleep-mode, ideal for battery-powered systems, and further extends battery life with an ultra-low 1 µA current in shutdown mode. The adjustable switching frequency range, internal loop compensation, and built-in protection features such as cycle-by-cycle current limit, thermal sensing and shutdown, and output overvoltage protection make it an excellent choice for the team’s demanding requirements.

For manufacturing the Buck Converter Test Board, the UTFR has partnered with PCBWay, a company that aligns perfectly with their commitment to quality and efficiency. PCBWay offers sponsorship opportunities for non-profit, crowdfunding, and cool projects, which can greatly benefit student-led initiatives like UTFR's. Teams can easily apply for sponsorship by contacting PCBWay at sponsor@pcbway.com or through their website.

PCBWay Website

To proceed from design to manufacturing with PCBWay, the team follows these steps:

1. **Select Service Type and Specifications**: 

Select the PCB service, fill in the required specifications, and click the "Calculate" button to continue.

2. **Choose Build Time and Shipping Methods**: 

Select the desired build time and shipping methods.

3. **Add to Cart**: 

Add the service to the shopping cart.

4. **Upload PCB File**: 

Upload the necessary PCB file in the shopping cart. The review of the order is completed in about 10 minutes.

5. **Payment**: 

Check the "Pass, Payment" status in the "Awaiting Payment" menu and proceed to checkout.

6. **Checkout**: 

Select or add a shipping address, choose a shipping method, and select a payment method. Discount and cash coupons can be applied if available.

7. **Confirmation and Production**: 

After successful payment, wait for the confirmation receipt and track the production process through the "Production Status" menu. 

This partnership with PCBWay not only ensures that UTFR's designs receive the best manufacturing treatment but also supports their ongoing quest for excellence in racecar design and functionality.

UT24 Buck Converter Test Board

By Nicholas Burley, UTFR Electronics Lead

The University of Toronto Formula SAE Racing Team (UTFR) is continually striving for innovation and optimal performance in the challenging world of formula racing. Our vehicle's electrical system is a testament to this dedication, ensuring efficient power management and distribution to various subsystems. They will be racing in Michigan, New Hampshire, Czech and Germany in 2024. 

The UT24 Buck Converter Test Board is the centerpiece of our endeavor to refine and optimize the power regulation of our car’s low voltage system. This test board aims to scrutinize the robustness and efficacy of the buck converter, which is poised to be a pivotal part of UTFR’s Rear Controller for our 2025 vehicle.

Figure 1: Initial design of the Buck Converter Test Board, featuring its compact layout.

As with many of our high-performance boards, JLCPCB has been our partner of choice in transforming our designs into reality. With over 15 years in the industry, JLCPCB's commitment to quality and efficiency aligns perfectly with our team's ethos. Their ability to manufacture intricate designs with precision, coupled with their cost-effective solutions, makes them the top contender in PCB manufacturing.

Design & Functionality

Figure 2: A detailed schematic of the Buck Converter Test Board in Altium Designer 2022.

The primary role of the Buck Converter Test Board is to evaluate whether the converter can adequately power our car's low voltage system, which includes peripheral boards, our battery management system, multiple sensors and our Cascadia inverter. Boasting a higher amperage output and having a footprint considerably smaller than previous iterations, this buck converter promises enhanced performance without compromising space. Operating at a swift 1.455 Mhz, it is designed to efficiently regulate a 21-volt LV battery to a stable 12 volts, suitable for vehicular operations.

Altium Designer 2022, with its advanced tools and comprehensive interface, was instrumental in bringing the Buck Converter Test Board to life. The software's capabilities, from intricate schematics to detailed 3D visualization, facilitated a seamless design process. The ability to instantly integrate with JLCPCB's manufacturing standards ensured that our designs remained compliant and optimized for fabrication.

Ordering Logistics with JLCPCB

JLCPCB's streamlined ordering process complements the intricate design capabilities of Altium Designer. Here's how we seamlessly transition from design to manufacturing:

1. Generating Gerber files: Within Altium, navigate to File -> Fabrication Outputs -> Gerber Files.

Figure 3: An in-depth view of the Gerber file generation process in Altium.

1. Uploading to JLCPCB: Access the user-friendly interface on JLCPCB's platform and upload the generated Gerber files for a quick review.
2. Specifications & Review: JLCPCB's system automatically detects the board specifications, minimizing manual input and expediting the ordering process.

1. Finalizing the Order: With options to adjust parameters like silkscreen colors and layer stack-ups, one can customize the final product. Simply add to the cart, input shipping details, and proceed to payment.

Conclusion

The UT24 Buck Converter Test Board represents our unyielding quest for perfection in racecar design and functionality. Our continued collaboration with JLCPCB ensures that our designs, realized using tools like Altium Designer, get the best possible manufacturing treatment. We invite our fellow designers and enthusiasts to experience the unparalleled service of JLCPCB, which can be explored further at https://jlcpcb.com/RAT.

UT23 Driverless Control Module v.1.1

By: Muaz Shash, Drivierless Team Member, University of Toronto Formula Racing Team

With the start of the 2023 Formula Student season, the University of Toronto Formula Racing Team (UTFR) has established a new department: Driverless. This team is responsible for developing an autonomous system that can operate our vehicle to score even more points at competitions and secure our spot on the podium. Like all other systems in our car, the driverless system requires an electronic controller to interface with the real world. The driverless controller is responsible for all critical control and safety decisions related to autonomous tasks, such as controlling visual and audio system status indicators, stepping up/down voltages, managing power delivery to steering, braking, and throttle, as well as communicating with the rest of the car's electric system over multiple CAN buses.

The Driverless Control Module includes many different components, such as a Teensy 4.1, two CAN transceivers, a 12V switching regulator, a 5V linear regulator, a 3V3 linear regulator, and a series of relays and MOSFET circuits. In this article, I will provide a high-level overview of how the driverless controller manages power and responds to autonomous commands.

Schematic Design

The driverless control module distributes four voltage levels: 14.8V, 12V, 5V, and 3.3V. The 14.8V comes straight from the battery and is intended for brakes, steering, and the shutdown circuit. The 12V is distributed to the system status indicator LEDs and speaker, the 5V is for the Teensy 4.1 microcontroller, and the 3.3V is for the CAN transceivers. You may also notice that there are plenty of LEDs and testing points. These are purely for debugging during testing and serve no other purpose

The controller features many MOSFETs and relays to control power. The vehicle features a shutdown circuit (SDC) that essentially disables the car from moving if any point in the SDC has been opened. On the driverless controller, this corresponds to the wires in blue. If the 3.3V Autonomous System Enable (AS_EN) signal controlling the MOSFET is low, the vehicle will never be able to move. If the 14.8V Autonomous System Master Switch (ASMS) is high, then this implies we are in autonomous driving mode and require the Remote Emergency Stop (RES), which can be controlled wirelessly, to be closed. If the ASMS is low, then this implies we are in manual driving mode and we can bypass the Remote Emergency Stop. The ASMS also controls whether power can be delivered to the brakes and steering motors. All of this is done using a force-guided contacts relay to prevent the possibility of the autonomous system taking over during manual driving.The UTFR team uses the Teensy 4.1 microcontroller that boasts a 600 MHz ARM processor and 3 CAN bus channels. The Teensy is responsible for managing the vehicle start and steering relays using the MOSFETs in the image above, controlling the steering and brake over PWM, communicating over CAN to the RES and the rest of the car's electrical system, and controlling autonomous status system indicators (ASSI). The ASSI are a speaker and RGB strips located around the car. The Teensy generates a square wave signal to control the speaker and pulls the blue/green/red pins low to make the RGB strips flash blue or yellow.In addition to simply sending out signals, the Teensy is programmed to monitor all of its signals to provide adaptive feedback. We constantly monitor the battery voltage to avoid loading too much stress on the battery and low voltage system throughout the car. We check brake voltage to see if autonomous braking is possible and brake pressure to see how hard we're pressing the brakes, and we read how much current is flowing through the autonomous system indicators to confirm the signal was sent and the connection is stable. Due to its robustness to noise, we also use the sensor CAN bus to read safety-critical sensor data collected from other parts of the...