Carter,
This new thread is in response to an inquiry on why we chose the Perm Motor for our 10 KW motor.
Choosing a motor is a bit of a moving target with new technologies coming online all the time. However there are very few motors that offer what the Perm does already in the 10 plus Kilowatt range. If there are other motors out there, I would be happy to hear if they can match my core criteria for a motor for a 20,000 lb boat up to 40 feet long :
- water cooling
- 94% efficiency
- up to 23 KW at 96 volts with torque up to 54 Newton Meters with peak torque up to 80 newton meters.
- double stator, brushless permanent magnet
- can be custom wound for a particular application. Ours was for 2000 rpm, 48 or 72 volts at 10 KW
- weight of 31 kg
- IP 54 protection
Its water cooled and hooking into the largest heat sink in the world ( the ocean ) just seems to be a good idea to me.
The people at Perm have been very clear as to what they can provide and participate in the design process. At this time our Perm Motor 10 KW is somewhat of a custom solution for individual clients. I have one in stock right now configured for 72 volts, which I think is a good idea once you get up to the 10 KW level. This means that all cables have to be shielded and you need ground fault monitoring to be ABYC compliant, which may be necessary for some insurance companies.
I spent some time in Germany with Perm Motors and met their engineers. What is most important to me is efficiency and having the majority of the energy go into the propeller rather than up in heat.
Efficiency is also relative to rpm, and they provide a map of that curve.
By being able to water cool the motor, you don't get thermal runaway. At 10 KW, bigger is better.
This motor will also form the basis of our larger motors to come in the 20 KW range. They will be run on 96 volts.
Perm also shares my view of conservatively rating products on a continuous basis at a specific operating temperature.
All of our motors are rated to be capable of crossing oceans, and for a bigger, heavier electric boat, this motor I believe makes the most sense at this time.
James
www.propulsionmarine.com
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