Executive Project Summary and Timeline

Executive Summary:

Group 21 have worked together This year to create a motor controller for energy-efficient vehicle competitio (Shell Eco-Marathon ). During Fall term of 2019, we had designs for the power supply, enclosure, PWM-signals, microcontroller, prototype PCB. During the Winter 2020 term we combined all of our sections to create a compete version and we were able to meet some of the engineering requirements. During spring term the project have been stopped due to COVID19.

Fall

First a few weeks of the term, our team spent a lot of time learning about the project scope and the end goal of the project. After clearing up any confusion the group had during our second meeting with our client, the group worked towards completing the high level system design such as making requirements and creating a block diagram. Additionally, the group decided how the different project roles would be split. The group continued to meet with the client throughout the term about every couple weeks. These meetings were used to make sure any new design ideas continued to align with the stakeholders idea of the finished product. By week 10, the group had completed the block diagram and systems requirements, and had completed the research required to implement the design.

Winter

During winter term the group determines the criteria required to prove that the project had met the requirements. During this time, one of the member in our group have left the group so we split his work between us. The group also started to begin implementing the design for the project. By week 3. the group had finished the user ordering the board and the materials, also finished the enclosure for the device. By week 6, the group had finished all of the blocks that had been finalized fall term. This included the first draft of the PCB and website. The winter term ended by verifying that are system met 6 of the 12 requirements.

Spring

Due to COVID-19, development towards completing the system stopped during spring term. This left a large amount of project management tasks for the group. The first few weeks of the term were spent finishing the project summary video and preparing the artifacts required for the virtual expo. After the virtual expo ended, the group moved to completing all the documentation for another group to continue the project. This included completing the closeout packet and updating and reorganizing the groups artifact repository to make information easier to find for anyone who adds to the project in the future.

Takeaways

One of the main takeaways from the project would be that our group have done the PCB but the test have been left duo to COVID-19. Due to the abrupt end to the project, our team hopes that another group will be able to continue where we left off, using the next step documents as a guide for new ideas to enhance the project.

Features of the project:

• STM32F4 microcontroller.
• DRV8302 MOSFET driver / buck converter / current shunt amplifier.
• IRFS7530 MOEFETs (other FETs in the same package also fit).
• 5V 1A output for external electronics from the buck converter integrated on the DRV8302.
• Voltage: 8V – 60V (Safe for 3S to 12S LiPo).
• Current: Up to 240A for a couple of seconds or about 50A continuous depending on the temperature and air circulation around the PCB.
• Sensored and sensorless FOC wich auto-detection of all motor parameters is implemented since FW 2.3.
• Firmware based on ChibiOS/RT.
• PCB size: slightly less than 40mm x 60mm.
• Current and voltage measurement on all phases.
• Regenerative braking.
• DC motors are also supported.
• Sensored or sensorless operation.
• A GUI with lots of configuration parameters
• Adaptive PWM frequency to get as good ADC measurements as possible.
• RPM-based phase advance (or timing/field weakening).
• Good start-up torque in the sensorless mode (and obviously in the sensored mode as well).
• The motor is used as a tachometer, which is good for odometry on modified RC cars.
• Duty-cycle control, speed control or current control.
• Seamless 4-quadrant operation.
• Interface to control the motor: PPM signal (RC servo), analog, UART, I2C, USB or CAN-bus.
• Wireless wii nunchuk (Nyko Kama) control through the I2C port. This is convenient for electric skateboards.
• Consumed and regenerated amp-hour and watt-hour counting.
• Optional PPM signal output. Useful when e.g. controlling an RC car from a raspberry pi or an android device.
• The USB port uses the modem profile, so an Android device can be connected to the motor controller without rooting. Because of the servo output, the odometry and the extra ADC inputs (that can be used for sensors), this is perfect for modifying an RC car to be controlled from Android (or raspberry pi).
• Adjustable protection against
  • Low input voltage
  • High input voltage
  • High motor current
  • High input current
  • High regenerative braking current (separate limits for the motor and the input)
  • Rapid duty cycle changes (ramping)
  • High RPM (separate limits for each direction).
• When the current limits are hit, a soft back-off strategy is used while the motor keeps running. If the current becomes way too high, the motor is switched off completely.
• The RPM limit also has a soft back-off strategy.
• Commutation works perfectly even when the speed of the motor changes rapidly. This is due to the fact that the magnetic flux is integrated after the zero crossing instead of adding a delay based on the previous speed.
• When the motor is rotating while the controller is off, the commutations and the direction are tracked. The duty-cycle to get the same speed is also calculated. This is to get a smooth start when the motor is already spinning.