I am working on a project to add two electric motors to the front wheels (or axel) of my auto, with a goal of generating 300 additional horsepower. My build will include on a specific-purpose 400V system, thus looking at the power requirements tells me that I would need ~225kw at roughly 560 Amps*. I recently read about your Hybrid Super Capacitors that include Lithium Ion batteries paired with your super caps; however, I’m struggling to understand what products to be looking at for my use case.
I’m not sure how much information is needed, but here’s the info I have available, with the caveat that most of these are soft variables, meaning that they’re what I’m working with until I know enough to change them based on better info.
Operating Temperature: the Hybrid battery will be mounted in the trunk of the vehicle, approximately 12’ away from the engine bay; maximum ambient temperature should be under 150F, plus whatever heat the hybrid battery generates. Cooling is available.
Duration: 5 - 10 continuous seconds of discharge with approximately 5 - 60 minutes for recharge between races. (Noting that faster is better, but some minimum rest will be provided between runs if only to reset at the starting line)
System will utilize a DC-DC converter, and a homebrew power management solution (unless a COTS version can be found).
System will complement an ICE rear-wheel drive only sports car, with the primary goal to decrease ET in the 1/8th mile or 1/4 mile, by turning the RWD into an AWD during peak demand, as determined by throttle.
System will allow for free-spin of the Electric motors after power deletion from the Power pack.
Future upgrades will include a regenerative braking integration into the power management solution.
System uses wire gauge of 4/0 AWG (0.65lb/ft), I think.
*Just a side note here that figuring out the amperage requirements has been somewhat complex for me.
- Power (P) = Voltage (V) × Current (I)**
Given:
- Power (P) = 225 kW = 225,000 W
- Voltage (V) = 400 V
Calculating Current:
Current (I) = Power (P) / Voltage (V)
Current (I) = 225,000 W / 400 V = 562.5 peak Amp requirement
However, EV manufacturers have been using Pulse Width Modulation, Motor controls, thermal management, and a battery / power management system to generate more power using smaller amperage requirements, so I’m confused on what my peak amp need will really be.
Given all this info, how do I size a LiC or a VMF/VPF Series Hybrid LIC solution that fits the demands of the system?
Thanks so much for any inputs.
Cauf E. Bean
Hello Cauf_E.Bean,
Welcome to the DigiKey TechForum.
Sounds like an interesting project. I hope you keep us posted on the progress, and the final results. We have some Engineers that monitor the TechForum, that should be able to help with this. Good luck with the project.
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Hello @Cauf_E.Bean,
Regarding the peak current for 300 hp:
- Assume a system efficiency of 80%
- Assume a voltage sag from 400 to 375 VDC
The 225 kW becomes 280 kW. Resulting in a current of 750 A. That assume 300 hp at steady state. You will likely need to account for inrush current which can be 3 to 5 times higher. Let’s call it 5000 A as a first approximations.
As for battery and LiC recommendations. I encourage you to look for experienced designers along with EV track regulations. This is a highly specialized application outside my wheelhouse.
As a side note, be sure to include appropriate safety fused. For example, track regulation may call for a pyrofuse to quickly (with explosive charge) disconnect the battery pack.
Best wishes,
APDahlen
P.S. I can’t overemphasize the safety hazards associated with this application. There is a high risk of electrocution. There are also fire and explosive hazards as the cell quickly discharge. Things will melt with potential for unquenchable fire.
P.P.S. You will need a battery management system to correctly monitor and charge the individual cells. This is another significant challenge especially given the 110-cell series string(s) used in the application. This is important as the entire pack is only as strong as its weakest link. To learn more please research the purpose of the multipin connectors typically found on RC battery packs.
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Thank you very much for your insights and thoughts. Specifically, the first half of this sentence is exactly what I am looking for (experienced designers). I will twist the second half of your sentence into a slightly different statement: ‘along with track regulations for EV Vehicles’. The point of this is to clarify, I’m not looking at EV only drag races, but rather a hybrid solution for hot rodders who want to add more ‘usable’ horsepower that doesn’t have to compete with the ICE for traction, and that even assists the rear wheels in better launch.
5000 A is a lot of amps in my non-electrical engineering brain (I have an ME instead). It makes me think that I’ll have to have garbage can diameter cables to avoid a meltdown. How do I size cables for a peak load versus steady state? Also, I am hoping to learn more about the Hybrid solutions that include Super Capacitors coupled with batteries for a higher power density while maintaining the unit as a dependable power source.
Battery explosions are a concern. I intend to liquid cool the battery box, which will be an explosion box (similar to the design that the 787 battery ended up in).
I had not even though of safety fuses - that’s a brilliant inclusion into the design.
Which brings me to my final point: this is the front end of something that has a very real commercial presence (mass-market EVs), but almost ZERO exposure to race-focused drivers and enthusiasts who would find a real value in this type of product. Note that I’m not considering Formula 1 because they won’t talk about their secrets inside the onboard MGUs, beyond a general overview, and they’ve been refining this tech since 2014. Ideally, though, they’ve figured it all out - too bad there’s no way to buy one or to see their engineering.
Thank you again!
Greetings,
You may want to consider contacting one of our design service partners through the link below. They should be able to provide the assistance you are looking for.
Design and Integration Services | DigiKey
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Indead, @Cauf_E.Bean,
Just typing the number 5000 bent one of my fingers. In practice the motor driver would self-limit before reaching this point, however, I think my point was made.
Higher voltage would get you out of this situation. For example, I believe the Tesla S1 has a nominal 900 VDC voltage. That would lower the 300 hp steady state current to a respectable 300 A with the unconstrained current to about 1500 A.
Keep in mind that your 225 kW (300 hp) system has the power of nearly 3 Tesla S1s. However, the energy is less, as you only need the power for a short burst.
Happy engineering.
Aaron
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This just goes to show how little I really understand of this, though I reaffirm my intentions to be more knowledgeable at it. When I google how much HP the Tesla Model S Plaid has, I’m given a number of 1,020HP, which converts to 750kw delivered from three electric motors, or roughly 250kw per motor. I want to add 300HP, which is roughly 1 of those motors’ worth of power. At least this made sense in my simplified mental approach. 300HP/2 (or 1/2 of that per front wheel) would be 150hp per wheel, which is just a fraction of the Tesla top performer.
So, acknowledging how little I understand in electrical engineering, I still made the assumption that if Elon can deliver an 8.5s 1/4 mile with the combination of these three motors, I should be able to see significant benefits by adding motors to my front drive train (either in hub or on-axel).
Next up, I don’t know what it means to say I’ll use a 900 VDC system over a 400 VDC system in terms of scaling the system’s individual components (I do readily follow the math that higher voltage gives the advantage of lower current.) Does having a 900VDC system mean that I have to have a 900 volt battery, or lower voltage but with transformers.
On the surface, I keep looking at the cost to implement a Supercharger (whipple 3.0L) or a turbo setup - both of which come at similar price tags around $16,000 and think to myself that I have to be able to implement a motor driven solution that would be half of this or less. I budgetted 400lbs for this build between components and battery(s), and hoped to build a solution for <$10k. I don’t have to drop the engine, I don’t have to cut into any systems (perhaps if I go with an axle driven solution I might need to both cut and weld), and motors - which along with batteries I assumed to be one of the most expensive parts - are available for under $3,000 (for both). I also made assumptions that I could buy a power controller unit in some form or flavor for ~$2000, and a DC-DC converter for half as much again. The rest of the budget was to connect it all together and tune it with a pro.
But I keep stumbling at the simplest step: defining the system, and seeing the calculations for amperage that were outside of my reasonable understanding only get me more spun around the axel.
I appreciate all your thoughts and help; if you happen to know where I can get more info on the engineering basics of Hyb Evs, I’d appreciate the link.
Thank you again!
Jason
My mistake, @Cauf_E.Bean,
I took the first reference for the S1.
You are correct, Tesla Model S - Wikipedia gives us 300 to 400 hp.
The battery voltage, inverter, and motor operate a matched pair. Each would be selected / optimized for a given voltage.
By chance, have you seen NetGain Motors. They have a variety of AC and DC motors along with inverters that may fit your application. See their photo album to see the exciting modifications to all things internal combustion.
Sincerely,
Aaron
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