Just to add it's actually more informative to just test PMSG in wind turbines, as alternators designed for use with high-speed submarine diesel engines operate at high rpm, but propulsion motors and wind turbine alternators operate at low rpm.
Yuan Class AIP & Kilo Submarine Thread
- Thread starter Jeff Head
- Start date
Is this why the Pentagon labels CRRC as a military firm and tried to ban it from bidding for rail projects in the US?
Let's not confuse reason (which a "why" question asks) with excuse.
Not true. LFP still makes heat. Just not as much heat as Lithium Nickel Manganese Cobalt batteries. But even with less heat, you still have to rely on some kind of cooling.
Your best reason for choosing NMC instead of LFP is due to NMC's superior power density. Its only recently we have seen advances in LFP such as LFMP that increases power density, either through packaging, chemistry or both.
well at least the ones by BYD doesn't have any heating related issues. The design decisions would have been made back in a time when LFP density was not very competitive to ternary batteries.
Anyhow, I asked a contact about the likelihood of fuel cells on 039C and he kind of threw cold water onto it. He thinks that China has not been too pleased with cost and power density of fuel cell design in general. They did come out with a 320 kw AIP engine with 40% efficiency last year (replacing the 4 x 75 AIP engines they had on 039B) that might be at play here. So he is looking at either pure LIB or LIB + this new single engine stirling combo. Either way, even the new single stirling engine should provide for higher speed, longer endurance + lower noise level (more easily to raft than 4 engines) than what they had with 039B.
They still generate heat, and the reason why the BYD LFP batteries are shaped like blades in the first place is to allow air to circulate between the blades and allow for maximum surface area for cooling. There's still a fan or fans somewhere to blow the air through.
Decisions could have been made by weighing cost safety advantages versus power density.
If you have air cooling, you definitely have something to move air around. Even hybrids have air cooling in their batteries.
The point is that if you see a cooling system with the battery pack it's not disproof that it's LFP.
I also asked my contact about PMSG. He thinks it's more plausible with nuclear subs, since diesel submarines largely run on D/C power. PMM is probably what they are using.
Also, he brought up that pressure hull for 039C looks the same as 039B based on water line. Something like fuel cell will most likely require changes in pressure hull.
I don't quite understand your contact's point on diesel submarines and DC power. Almost all modern generators are alternators, fitted with AC-DC converters if needed. In particular all PLAN vessals use high-speed alternators.
The article is about Xiao Fei and his work. Xiao Fei worked on high speed induction generators for PLAN in the early 2010s and worked as part of Ma Weiming's team on subsequent new generator designs which are installed on all PLAN vessels in active service or under development. Xiao Fei is an expert on power conversion and has been in charge of converter design for those generators.
In around 2008, at the suggestion of Ma Weiming, Xiao Fei had applied his work on high speed marine generators to solve Chinese wind turbine industry's struggle with converters, and successfully designed a converter for a 2MW direct drive wind turbine PMSG.
Anyway it's clear from the article that all PLAN vessals use high speed alternators and then convert AC to DC if needed. This is not surprising at all since almost nobody uses DC generators nowadays.
Also it's interesting that the article claims Ma Weiming's high speed generators are now standard on all PLAN vessels in active service. PLAN must have done a lot of retrofitting.
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