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Ronan Njøs
Group Leader for Chassis
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To save cost and labour, we decided we would investigate the possibility of re-using the tooling from 2020. If we are be able to do that, we can save a fair bit of work and money. Our tooling was in Kongsberg, so we had to drive down and get it from our sponsor, the Kongsberg Group.
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We were determined to do it as soon as possible and drove down at Monday right after the concept review finished. Herman and I (Ronan) decided to leave 5.30 am from Trondheim. We got to the offices around 5am to prepare the car and trailer for the trip and left around 5.30am. We arrived in Kongsberg around 14.30pm. We met up with Simon Ekornsvåg in Kongsberg and loaded up all the things left in Kongsberg. We got our things from both Krona and the Kongsberg group. We drove back up the next day and arrived back in Trondheim Tuesday evening.
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Picking up the tooling was only half the job. We also needed to demould the tooling to see if it was usable. We scheduled to do it later that week on Friday. On Friday at 16.30, the Chassis group + Christian and Phillip started the demoulding process. This was a very educational process for the Chassis group since we got an insight into the production process. The demoulding process consisted of taking the half finished monocoque out of the tooling. We did this for the upper and lower part of the monocoque. This process took a few hours, but we managed it and the tooling was undamaged. This means we can now use re-use the tooling, which is great news.
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Eskil Mogstad
Inverter & Motor Controller for Embedded Electronics
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The inverter is the power electronic device in the vehicle that changes the direct current from the battery accumulator to three phase alternating current for the motor. To change DC into AC, power electronic switches are used, controlled with pulse width modulation/PWM. There are four inverters in the vehicle, which allows independent control of the four motors.
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In 2019, Revolve NTNU integrated its first inhouse developed inverter and motor controller into NOVA. It featured SiCMOSFET switches and used field oriented control to control the four permanent magnet synchronous motors in the vehicle.
During the summer, due to the lack of competitions, the time was spent wisely, redesigning both the control card and the powerstage of the inverter, in an effort to both increase the maintainability and reduce the overall size and weight of the system. Maintainability was a problem area with the previously developed system, requiring at least two people and many hours to assemble.
Both the schematics and the layout of the circuit boards were designed in Altium Designer 20. A lot of different packaging concepts were investigated using the Multiboard feature of Altium Designer, where several PCBs and STEP models were assembled together, to find an assembly which would be easy to assemble and use the space efficiently.
NCAB gave technical support during the layout process, helping in determining the PCB stackup, including layer thicknesses and impedance profile for edge coupled microstrip routing, in addition to being responsible for the production of both the PCBs and the solder paste stencils.
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During week 40, me and Jan Seljebu Olsen, the inverter responsible for Revolve NTNU this season, went to Simpro to assemble the newly arrived PCBs. A lot of time was spent beforehand to prepare production documentation and organize components to be as efficient as possible during the production.
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Four control cards and three powerstage boards were produced during the three days. The first day was spent picking out components, the second day was spent assembling the bottom side of both boards and the final day was spent assembling the top side of the boards.
We are using reflow soldering to assemble the boards. This is done by applying solder paste to the blank PCBs and then placing the components on the paste before putting them in the oven. This makes the assembly process very efficient in addition to making good solder joints.
Testing of these boards have just begun, and the rest of the fall will mainly be spent testing the new hardware in addition to writing software to interface with the new hardware. For testing the power electronics on the powerstage, a testing method called double pulse testing will be used. On the software side, code for interfacing with new hardware will be implemented, while motor control code will be ported over from the previous system.
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Mats Erik Haugan
Head of Production
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Composite Room
The composite room is the heart of Revolve’s composite production. Here all our inhouse produced composite parts, except the monocoque which requires bigger areas down in Kongsberg, come to life. All the aerodynamics that you can see on the car started their life in a mould in this room before a trip to the oven made them the beautiful parts you see on the car. You can call this room the Aero-groups` other home during the spring semester, countless hours are spent here perfecting every part. You could say the composite room is where dreams become reality.
Workshop
The Workshop is where we spend most of our time during the spring semester. After the design work is done, most of the team move here to start building the car. As soon as the monocoque returns from the paintshop and the paint has dried, members start putting their own design parts on the Monocoque. Just before the unveiling, and after many hours of labour, we can finally call it a racecar.
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During the summer this is where the revolve crew live. The day shift packs all the necessary equipment for a day of testing the car. They return with more knowledge about the car, and briefs the night shift of the day's progress, and things that need to be fixed on the car during the night. It is during this time members become Revolvers!
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Embedded Electronics Rooms
The Mechatronics lab, or "Mecha" as we call it, is one of the most important places for the Electric team members. This is where we debug, test and validate the designs we do throughout the year. Revolve NTNU has two design phases for the electrical systems, the prototype phase and the production phase. The prototype phase is where we implement concepts that improve the systems from last year and test that the new designs work as intended. The production phase is when the PCBs for the cars are produced. For the production run, we mainly fix errors with the prototyped design. Major design changes are rarely done for here.
We actively use "Mecha" when working on the PCBs. The most important equipment we have there are our soldering stations, which we have gotten from Weller, and our testing stations where we have our power supplies, oscilloscopes, and multimeters. In addition to this, all the PCB components we use are stored here with the most essential wire harness equipment for testing our PCBs.
Another place that is important for some of our electrical members is the inverter testbench. This is a dedicated area in our workshop used to test our in-house developed inverters. Here we are able to double pulse test our power stage and test our control card and control algorithm because of the equipment we got from 4Test and Itech last year. The ability to continuously test the inverter gives us the opportunity to push development at a fast pace while not being reliant on the rest of the car to do so.
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