Drone Power Distribution Board

Designing a Smart Power Distribution Board for Drones

During my summer job at the University of British Columbia, I had the opportunity to work on developing a smart power distribution board (PDB) for drones. The goal of this project was to design a board that could effectively distribute power to 6 ESC’s as well as step down power from a 6S LiPo battery to 12V for the flight controller and provide current and voltage telemetry.

Implementing the Design

Voltage Regulation

The easiest way to step down voltage is to use the WeBench Power Designer from Texas Instruments. I simply plugged in the design requirements and it generated a schematic for me.

Current Sensing

Instead of using traditional shunt resistors for current sensing, I decided to use a hall effect sensor. This allowed for more accurate current measurements, faster response times and less power consumption and therefore less heat generation. I integrated an Allegro ACS37220 an ultra small QFN package hall effect sensor that could measure up to 200A of current.

Voltage Sensing

While I could have used a voltage divider to measure the voltage of the battery, I went for a INA226 voltage and current sensor. I just didn’t use the current sensing capabilities. However this just made everything easier as I could simply connect to it over I2C and get voltage readings.

MCU and Telemetry

For the microcontroller, I used a STM32G0B1KBU6 which is a small 32 bit ARM Cortex M0+ microcontroller. This could read data from the sensors and integrates a built-in temperature sensor. From there I connected this to a CAN bus transceiver and sent the data over CAN to the flight controller. This allowed for easy integration with the flight controller and also allowed for easy expansion in the future. It also provides a more robust communication protocol than UART or I2C which is especially important for drones as they are subject to high levels of electrical noise. I learned that electrical noise can be a big problem when using I2C from my work on the Marine Robotics Club.

For programming the microcontroller, I implemented a Tag-Connect pogo pin interface which allowed the board to stay as small as possible while still allowing for easy programming.

Assembly and Testing

After soldering and fixing some solder bridges, the board successfully powered up and stepped down the voltage to 12V. I was also able to program the microcontroller and read data from the sensors using a ST-Link programmer.

Conclusion

Through this project, I really gained experience not only in designing and implementing a power distribution board design. But making a design that looks beautiful.