P17280: Hot Wheelz Thermal Management System
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Missy's Work

Table of Contents

The purpose of this page is to show my individual contribution on the P17280 Hot Wheelz Thermal Management System MSD project. Initially, the MSD-required logbook was utilized for Phases 1 (Problem Definition) and 2 (Systems Level Design). However, after analyzing the amount of time it spent to update the logbook with content, it was determined that posting it directly to EDGE would be more efficient.

MSD I Deliverables

Phase 1: Problem Definition

The work for this phase can be found in my logbook.

Phase 3: Preliminary Detailed Design

The work for this phase can be found in my logbook.

Phase 3: Preliminary Detailed Design

The work for this phase is outlined and linked below.

Work Breakdown Structure

  1. Identify current available for controller fan
  2. Identify pros and cons of using fan on controller
  3. Build and troubleshoot electrical system on testbench
  4. Keep team on track
  5. Update plan and WBS

Deliverable 1

Purpose: Identify current available for controller fan to initiate sourcing and pro/con analysis

After a meeting with the Circuit Design subgroup lead, I was informed that we would have a max of 2A of current for use of a fan to cool the controller. This value was very similar to the value that Caitlin had obtained for her fans, so we determined as a team that it was not necessary to source different fans until we knew if we wanted to move forward with the concept or not.

Obtaining this information allowed me to move on to the next deliverable.

Deliverable 2

Purpose: Identify pros and cons of implementing a fan across the controller in addition to heat sink to determine if further sourcing and research on mounting methods is required.

We would need to do the following:

After communicating with the Hot Wheelz programming/telemetry group, I identified that there are only three drivers available. One is rated for a max 3A current output, while the others are limited to 2A. All are protected against shorts to ground, which is an added safety feature that is helpful for Hot Wheelz.

Based on this information, a preliminary electrical schematic was created for the controller and can be viewed here.

Relays were not sourced at this stage for two reasons. The Hot Wheelz team has multiple relays at their disposal that we could utilize for testing/design if needed. Also, the team was leaning towards not using a fan by the time I got to this part of my deliverable, so in order to be more efficient, I didn't source specific relays since they may not be utilized.

I had an in-depth conversation with the controller SME regarding how to program the controller to use the internal controller temperature to power the fan, so if we do decide to go that route, I not only have a basic understanding of the concept but have a contact willing to provide extra assistance as needed.

Prior to the Phase Review, the team discussed the research outlined above. Since Kristin and Jordan are confident that their design can manage the worst case scenario, they don't see the need for the complexity or current pull of the fan. Caitlin and I agreed. Additionally, since Hot Wheelz is very limited in space for electronics, adding relays could be more of a hassle to them if it's not necessary. The current plan is to not proceed with this concept for the final design, however fans may be tested during the testing phase of MSD-II. If it turns out that fans can greatly improve the performance and efficiency, we may re-analyze this decision.

Deliverable 3

Purpose: Build and troubleshoot electrical system on testbench so that we can obtain temperature data on the controller.

Due to the competitive nature of the competition that Hot Wheelz participates in, not all of the information and schematics can be shared via EDGE.

Hot Wheelz removed the electrical system from the vehicle and transferred it to the testbench. They needed help/more resources to finalize the electrical wiring and troubleshooting. I spent many hours every day for about a week to get this up and running. You can view a basic schematic of the high voltage ("Tractive System") components here, but note that I had to modify ALL wiring schematics for all systems of the "vehicle" due to simplification and errors we were obtaining, including the BMS (battery management system), GLV, shutdown, IMD, and latching circuit. These were all shared with Hot Wheelz so they could easily refer back when they go to to troubleshoot the testbench for their own purposes.

We also found out during this time that there were issues with the previous MSD project and could not utilize the program that they created to run the dyno. Our customer was in town one weekend, so Jordan and I met with her for a day to try to get this to work and understand what was going on. I also worked with Caitlin and a friend to try to go through the program and see what errors were coming up. We finally gave up on this and decided to move into the manual mode, which Jordan took responsibility for so I didn't have to worry about.

During testing, I was also responsible for ensuring that the electrical system was running properly. I assisted in checking the voltage of the system before and after tests, as well as identifying a method to check cell voltages continuously during a run. However, due to issues with the dyno, we were unable to complete testing. This information can be shared with Hot Wheelz though for future testing so it wasn't a complete waste.

During the testing phase, I also reached out to multiple resources to try to find ways to get the dyno to work or identify a different method to apply a load to the controller/motor. I reached out to our Guide, Customer, and multiple stakeholders. Everyone provided really great ideas and feedback, but in the end, it was not feasible for the team to continue with any of these concepts. The information that was obtained will be passed onto the Hot Wheelz team for their reference in case they decide to look into it. Some ideas that were brought up were:

Deliverable 4

Purpose: Keep team on track.

The thought behind creating a deliverable for this was to aid the team in meeting their objectives for the phase.

A project tracking sheet was created and can be viewed here. The first sheet was to show the team the progress on our desired objectives for the phase. Progress reports were delivered each week, and the timeline was modified as needed. The new due date was then added to the spreadsheet. The second sheet was created about a week prior to the review in order to aid in the completion. I spent a good amount of time setting up the EDGE page to match the Metrics of Quality and assigning the work to the team. I then populated this spreadsheet to hold each other accountable for the work.

Deliverable 5

Purpose: Update plan and work breakdown structure for rest of phase and for Phase 4.

The timeline was updated each week based on progress. The final revision for the end of the third phase and transitioning to Phase 4 can be seen here along with milestones for MSD II that were designed to align with Hot Wheelz deadlines.

The work breakdown structure for phase 3 was updated to reflect the actual work done and be viewed here.

A preliminary work breakdown structure for phase 4 was created and can be viewed here.

Other Work

In order to finish the EDGE page and rest of material required for the review, I also took on the following items:

  1. Project objective statement - "Deliver a thermal management system for the batteries and motor controller to maintain optimum temperature for competitive performance."
  2. Systems arhchitecure- view here
  3. Updating risk assessment - view here
  4. Risk Plotting - view here
  5. Risk Mitigation Plans - view full document here
  6. Action Items - documented notes and action items from review. Full doc here

Phase 4: Detailed Design

Work Breakdown Structure

  1. Identify temperature range for batteries
  2. Create test plans
  3. Source fans and circuitry for BMS
  4. Create detailed electrical schematic for BMS fans
  5. Update and track risks
  6. Update and track project plan / team WBS
  7. Identify waterproof method for controller & fans
  8. Help teammates

Deliverable 1

Purpose: Identify temperature range for batteries

A sample set of batteries were sent to a GM mentor at a battery lab for testing. Despite attempts to reach out regarding the test conclusions, the data results were not able to be obtained this phase. I will continue to try to get this information moving into MSD II.

Since the information was lacking, I called the battery manufacturer, Headway Headquarters LLC to ask them for recommendations. They said that 60 degrees C was the recommended limit since that is when the ions start to degrade. Full thermal degradation occurs around 80 degrees C.

Headway also recommended setting a discharge limit of 2.5V per cell since that is when the battery cell will start to lose its energy.

Total time spent on deliverable: ~1 hour

Estimated time if had to do a second time: ~30 mins

Reason it took so long: Tracking down information from different sources

Deliverable 2

Purpose: Create test plans
Testing Relay & Programming
Researched wiring and programming of relays/fans in BMS in order to determine a) if the relays that the Hot Wheelz team already had in inventory would work for system and b) that firmware update of BMS was successful and c) what type of control we could have over the system. A full test plan can be viewed here.
Waterproofing
A preliminary test plan was drafted for testing the waterproofing of the fans. The full document can be viewed here. These can be modified for the controller as well.
Strain Relief
Research was done on the strain relief testing performed at Formula Hybrid. According to the rulebook, the judges will use a spring-loaded scale set to 200N which would be placed on tractive system wires/conduit. This is a more precise method of measurement than last year's inspection, in which the judge simply pulled on connections. A spring-scale that can handle 200N would cost about $150 from McMaster. The team discussed this at length and determined that the 200N would be equivalent to a hearty-tug by any team member.

Total time spent on deliverable: ~3 hours

Estimated time if had to do a second time: ~1.5 hours

Reason it took so long: Had to do a lot of preliminary research

Deliverable 3

Purpose: Source fans and circuitry for BMS

Obtained a minimum value for static pressure of fans (20 Pa) from Caitlin. Spent a lot of time researching and sourcing fans. Also had to consider a number of other parameters. Full information on each fan sourced can be viewed here.

Total time spent on deliverable: ~10 hours

Estimated time if had to do a second time: ~6 hours

Reason it took so long: Had to convert units and consult with team often on findings

Deliverable 4

Purpose: Create detailed electrical schematic for BMS fans

After testing relay and ensuring fan worked with relay, I was able to update the schematic. I decided to use the Hot Wheelz schematic template to not only save Hot Wheelz time, but also to ensure that the needs of the Senior Design project were documented from Hot Wheelz side. The schematic can be viewed here.

Total time spent on deliverable: ~1 hour

Estimated time if had to do a second time: ~45 mins

Reason it took so long: Used Hot Wheelz template

Deliverable 5

Purpose: Update and track risks

Updated likelihood and severity of risks. Identified changes made. Updated the plot of importance reducing to zero. Highlighted when risks would reduce to zero and why we thought that they would reduce. The full analysis can be viewed here.

All of the analysis and documentation on the DDR page regarding risks was also completed by me.

Total time spent on deliverable: ~1 hour

Estimated time if had to do a second time: ~30 mins

Reason it took so long: Updated all at once

Deliverable 6

Purpose: Update and track project plan / team WBS

At the end of most meetings, minutes were sent out to the team with identified deliverables for each team member. This information was then used to update the project plan in order to identify what would be pushed back or delayed. The minutes did take a long time to do, but it also helped the team stay on track and feel more organized. Since there are so many of these documents, these were not uploaded to EDGE. If anyone would like to reference them, they can be viewed on the Hot Wheelz Google Drive folder under Phase 4 > Team Meetings and Updates. For access, please contact the Project Manager.

Additionally, the full project plan file can be viewed here and the Phase 4 WBS can be viewed here.

Lastly, all of the sections under Project Plan & Budget on the DDR page were completed by me.

Total time spent on deliverable: ~11 hours

Estimated time if had to do a second time: ~9 hours

Reason it took so long: Kept meeting minutes and updated plan after each meeting

Deliverable 7

Purpose: Identify waterproof method for controller & fans

Initially, this deliverable was to identify methods for waterproofing. It morphed into also finding a way to adhere to the strain relief rule. Research was done into silicone self-fusing tape, marine-grade adhesive lined heat shrink, liquid electrical tape, and enclosures. The enclosure research helped unearth the rule about the strain relief. A rules ticket was submitted to Formula Hybrid through the Hot Wheelz Rules & Safety Officer (RSO) to double check the meaning. It was determined that since the controller was going to be taken out of the box, we have to have a method to relieve the strain aside from the physical connection to the controller (i.e. the lug). We decided to go with conduit fittings which the conduit could then anchor in. In order to use these, we would need to create some type of structure above the controller to mount the fittings in. This led to a re-design of the heat sink assembly, which I assisted Kristin with.

In terms of waterproofing the connections, I decided on the marine-grade adhesive lined heat shrink. This would be shrunk over the entire connection and lug to the controller.

In terms of waterproofing the fans, we won't know what kind of waterproofing is needed until they are in house. If the connections are exposed and water would be a risk, we can look into either the liquid electrical tape or corrosion spray.

Total time spent on deliverable: ~4 hours

Estimated time if had to do a second time: ~2 hours

Reason it took so long: Ran into another rule issue

Deliverable 8

Purpose: Help teammates

I helped my teammates where ever I was needed during this phase. This included working on the prototype, adding all of the components to the BOM for the EDGe page as well as the Hot Wheelz system for ordering. I assisted with the design concept of the controller 'lid' as we are calling it. I also did other sections of EDGE that were not complete yet such as the Systems Architecture and other general sections.

Total time spent on deliverable: ~6 hours

Estimated time if had to do a second time: ~6 hours

Reason it took so long: Things that popped up