Designing a brushless AC motor for Formula Student

In summary, designing a brushless AC motor for Formula Student involves creating a powerful and efficient motor that can withstand the high speeds and demanding conditions of the Formula Student racing competition. This requires careful consideration of factors such as weight, size, and cooling methods, as well as selecting the appropriate materials and designing the motor's components to work together seamlessly. Additionally, the motor must be able to provide precise and responsive control for the driver, making it a crucial element of a successful Formula Student car design.
  • #1
Frosteh
8
0
I am on a Formula Student team and we have decided to design our own brushless AC motor. Our main issue is how we will cool the motor, since we want to keep weight down while also increasing power output. We will be making the rotor from forged Titanium (Ti6Al4V) and the housing from forged 7075-T6 aluminum. We want to use water (or a water/ethylene glycol mix) to cool the aluminum housing which will be cooling the magnets and coils. The main concern is that somehow the polarity of water will affect the workings of the magnets and reduce our power output. Is this an issue? Our other idea was to circulate mineral oil (like the stuff used in transformers) around the coils directly to cool them. Which would be a better method and do we have anything to worry about if we use water/EG to cool it?

Second, we are wondering about winding the magnets. If we want a higher power to weight ratio, should we use smaller gauge wire and more winds, or larger gauge wire and few winds around the magnet?
 
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  • #2
Don't really know about cooling brushless motors, but.

Formula Student team
rotor from forged Titanium (Ti6Al4V)
housing from forged 7075-T6 aluminum.

You must be bloody well funded.
Has anyone costed this?
 
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  • #3
xxChrisxx said:
You must be bloody well funded.
Has anyone costed this?

We're actually broke as ****. My dad's company forges structural pieces for Boeing's planes and is being generous to donate the blocks we need. Not pressed into the shapes yet, as tooling costs would be roughly $200k, but we have the tools to machine aluminum and titanium. If this were priced out, though, it would be damn expensive, that's for sure.
 
  • #4
Buy one. From steel.

Thats part of engineering. There are about a million brushless motors out there. There will be one that fits your needs, and if someone has a catalogue part that's works perfectly well. You don't design a bespoke one yourself. As one offs cost an absolute fortune.

If you agree to slap a sponsor sticker on you may even get it free.
 
  • #5
xxChrisxx said:
Buy one. From steel.

Thats part of engineering. There are about a million brushless motors out there. There will be one that fits your needs, and if someone has a catalogue part that's works perfectly well. You don't design a bespoke one yourself. As one offs cost an absolute fortune.

If you agree to slap a sponsor sticker on you may even get it free.

While there are tons of brushless motors, very few have the specs we're looking for. The best fit for our application is the YASA-750, which costs $11k. They've already said they won't sponsor us. The motor we're going to use needs to be less than 10kg, output ~35kW, and fit our budget. Since we have the CNC mills and tools to mill the parts, and the metal is donated, it's much cheaper and more effective for use to design and build our own. Motors are quite cheap, considering they are basically metal, magnets, and copper wire.
 
  • #6
So is this a pure electric formula, or some kind of hybrid?

Not having something available (at a sensible price) is a pretty good reason for building it yourself. It's good that you have invesigated buying a motor first.
You see it all the time with students, they think they have to design everything and don't consider buying stuff out.

Sorry I couldn't help with the motor or cooling question.
 
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  • #7
xxChrisxx said:
So is this a pure electric formula?

Not having something availalbe is a pretty good reason for building it yourself.

Indeed. We actually have two cars: one running a 4 banger (not sure which motor, since I'm not working on that car) that we'll run this year, and the electric one which will be complete next year.
 
  • #8
I would suggest that you better get someone who knows what they are doing to work on the electromagnetic design of this motor. Without that, you could easily wind up with a lot of machined pieces wrapped in wire that produce little or no power. Remember that this all has to function with your power supply. There are lots of concerns ab out getting the maximum current to flow (to produce maximum torque), which involves a lot of electrical considerations. You also have to worry about just where the heat will be generated and how you can get it out.
 
  • #9
If Dad's got connections at Boeing...
perhaps see what he can find out about aircraft generators like the first four here:

they're lightweight rotating machines on same order of magnitude you're contemplating...

http://www.ips-llc.com/products.htm

if you could find one on surplus market to study..
 
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1. What are the advantages of using a brushless AC motor for Formula Student?

There are several advantages of using a brushless AC motor for Formula Student. First, they have a higher power-to-weight ratio compared to traditional brushed motors. This means they can deliver more power while also being lighter, which is crucial for racing vehicles. Additionally, brushless AC motors have a longer lifespan and require less maintenance since there are no brushes that wear out over time. They also have a higher efficiency, meaning they can convert more of the electrical energy into mechanical energy, resulting in better performance and longer battery life.

2. How is the speed of a brushless AC motor controlled?

The speed of a brushless AC motor is controlled by an electronic speed controller (ESC). The ESC uses sensors to detect the position of the rotor and then adjusts the frequency and voltage of the alternating current to control the speed of the motor. This allows for precise and smooth speed control, making brushless AC motors ideal for racing applications.

3. What factors should be considered when designing a brushless AC motor for Formula Student?

When designing a brushless AC motor for Formula Student, there are several factors that must be taken into consideration. These include the power requirements, weight restrictions, size limitations, and cooling methods. The motor must also be designed to withstand the high speeds and constant vibrations of a racing vehicle. Additionally, the motor should be efficient and reliable, as any mechanical failure during a race could be dangerous for the driver.

4. Can a brushless AC motor be used for both acceleration and braking in a Formula Student vehicle?

Yes, a brushless AC motor can be used for both acceleration and braking in a Formula Student vehicle. This is because the motor can be controlled to rotate in both directions, allowing for regenerative braking. When the vehicle is braking, the motor acts as a generator, converting the kinetic energy of the vehicle into electrical energy, which is then stored in the battery. This not only helps to slow down the vehicle but also recharges the battery, increasing the efficiency of the overall system.

5. How can the efficiency of a brushless AC motor be improved for Formula Student?

There are several ways to improve the efficiency of a brushless AC motor for Formula Student. One way is to use high-quality materials and precision engineering to reduce friction and heat loss within the motor. Another way is to optimize the design of the motor, such as the stator and rotor shape, to reduce drag and improve the magnetic flux. Additionally, implementing advanced motor control algorithms and using high-efficiency electronic components can also improve the overall efficiency of the motor.

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