February 9, 2018

Possible Motor Modifications for Australia's Future Submarine

wispywood2344's diagram of a Soryu class submarine. To accommodate more powerful motor(s) changes like a longer section 12 (at the back) would be required. See larger, more readable, image of the diagram at http://blog.livedoor.jp/wispywood2344/others/Soryu_cutaway.svg
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Submarine Matters has lately concentrated on diesels for Australia Future Submarine but motors are equally important in submarine generator sets (gensets).

Anonymous has kindly made comments of January 19, 2018 on submarine motors. The comments have been further translated by Pete.

Japan’s proposed submarine design “SEA-J” for the Australian Future Submarine (SEA 1000) competition was to be 92m long. Naval Group of France won the competition in April 2016, but it is still relevant how Japan would have handled the more powerful propulsion solutions for a large Australian submarine. Relevant because Naval Group will need to resolve similar propulsion issues.

SEA-J is 8m longer than Japan's already built Soryu submarine’s 84m. In the cutaway diagram above the main motor section (12) was lengthened by 2m to improve the performance of the main motor. As SEA-J would have been required to transit long distance (perhaps 3,000 km each way) and at high speed, the durability and reliability of the main motor is all the more essential. The motor’s durability could be improved by measures such as adopting a tandem connection of two main motors. This results in longer length.

Neodymium magnets (which experience thermal and electrical environmental degradation) and bearings (which experience wear) are used in a submarine’s Permanent Magnet Synchronous Motor (PMSM). A PMSM uses permanent magnets embedded in a steel rotor to create a constant magnetic field. The stator carries windings connected to an AC supply to produce a rotating magnetic field. To prevent damage, the magnets, made out of Neodymium are kept cool. This is achieved by limiting the rotation speed/load and limiting bearing temperature. 

Japan's current Soryu Mk.I (with LABs and AIP) is equipped with one SMC-8 main motor. This is the first time the Soryu’s motor has been named in English to Pete’s knowledge.



The SMC-8 consists of two rotors and three bearings (two journal bearings which support the cylindrical rotating shaft at bow and stern sides, and one thrust bearing in which supports the axial load caused by propulsion at stern side). The SMC-8’s maximum output is 5.9 MW.

The tandem motor consists of two motors (four journal bearings, one thrust bearing). The load at each journal bearing will reduce than single motor (two journal bearings, one thrust bearing) with same output, because weight of rotor per unit journal bearing reduces. Disadvantages of tandem motor are unchanged thrust load, increased size of motor, increased number of vibration sources (increased number of bearings) and so on. A tandem motor may be suitable for large conventional submarine or nuclear submarine.

Regarding motor components, of interest is the RENK Company of Hanover, Germany's “Propulsion Motor Bearings and Thrust Bearings for Naval Application (Submarines)” document (PDF 2MB). In it: 
-  A stern side picture of a PMSM motor is shown at Fig. 3, on page2.
-  Most western submarine builders including Naval Group, TKMS and Navantia (S-80s) use RENK
   products. See page 4 which indicates “Over the last 50 years RENK slide bearings [have]
   equipped...more than 160 submarines.”

By Anonymous and Pete

11 comments:

Anonymous said...

Hi Pete

Before correction
The SMC-8 main motor consists of two rotors and two bearings. The SMC-8 main motor’s maximum output is 6 MW. If two small main motors (eg. 4 MW each or total?), each consisting of a single and smaller rotor and two bearings, are connected in tandem, the load on each bearing would be significantly reduced, improving the durability of motors.


After correction and addition
The SMC-8 consists of two rotors and three bearings (two journal bearings which support the cylindrical rotating shaft at bow and stern sides, and one thrust bearing in which support axial load caused by propulsion at stern side). The SMC-8’s maximum output is 5.9 MW.

In tandem motor consisted of two motors (four jounal bearings, one thrust bearing), load at each journal bearing will reduce than single motor (two jounal bearings, one thrust bearing) with same output, because weight of rotor per unit journal bearing reduces. Disadvantages of tandem motor are unchanged thrust load, increased size of motor, increased number of vibration sources (increased number of bearings) and so on. Tandem motor may be applicable for large convensional submarine or nuclear submarine.

Regards

Peter Coates said...

Thanks Anonymous

I'll alter the text accordingly.

Regards

Pete

Anonymous said...

Hi Pete

Jeumont Electric, possible supplyer of generator and propulsion motor for Shortfin shows MAGTRONIC system for submarine [1-5]. Figure [1] shows tandem connected motors with significantly increased size. As large output is expected for tandem motor and exchange of Nd motor is difficult, heat restistant Nd magnent, which is slightly less maximum energy product (key figure of performance for PMSM) but shows less thermal degradation, may be suitable for large or nuke submarine. Hot water from bearing or magnent is transported by small motor, which is vibreation source, to heat exchanger for cooling. Aslo heat radiation through large fin on motor surfaces are adopted [1-5]. Mountings of PERMASYN and MAGTRONIC are different each other [5] which may affect anti-vibration feature. Water cooling pipes seem to be set on the side of motor, but in PERMASYN pipes are set in front/ back side of motor?


[1]http://www.jeumontelectric.com/wp-content/uploads/2015/12/JE-Marine.pdf
(Power and propulsion system), page3/6, right hand side pictute “Generation and propulsion in a submarine”

[2]Ibid, page 3/6, right hand side picture “Combined test of Scorpene propulsion motor”

[3]Ibid, page 4/6, right hand side picture “PM synchronous propulsion motor”

[4]https://www.jeumontelectric.com/actualites/le-premier-des-six-sous-marins-indiens-scorpene-debute-ses-essais-en-mer/?lang=en (FIRST INDIAN SCORPENE-CLASS SUBMARINE BEGINS SEA TRIALS). Front view (bow side view)
An engineer is adjusting green pipes for water cooling of bearing. Two white boxes above the bearing shaft seem to be for sensors.

[5] https://www.naval-technology.com/contractors/electrical/jeumont-electric/ Overall view of [4]
Silver large pipes connected flanges are for water cooling of magnet. The side of motor is vertically supported on the hull, while lower oblique side of Siemens PERMASYN is obliquely suppored.

Regards

Anonymous said...

Dear Pete,

I found a nice PDF about Siemens motors:
http://w3app.siemens.com/mcms/infocenter/dokumentencenter/cc/InfocenterLanguagePacks/SINAVY%20DC-Prop%20and%20SINAVY%20PERMASYN®/sinavy-dc-prop-permasyn.pdf

Regards,
MHalblaub

Anonymous said...

Hi Pete

MAGTRONIC, PERMASYN and SMC-8s are perfectly different. I think in MAGTRONIC, elementary module comprises stator at least one sub-assembly, at least one rotor sub-assembly and at least one casting element connected to the stator sub-asssembly, the said sub-assemblies being dispose coaxially. PERMASYN comprises inverter, rotor and stator being dispose concentricly from the shaft to the inner surface of motor cylinder. SMC-8s comprise seem to two rotors on the shaft and stators on the inner surface of motor cylinder.

Features of these motors should be understood to make correct choice of PMSMs.

Regards

Peter Coates said...

Hi Anonymous

Thanks for the information at 10/2/18 2:57 PM and 11/2/18 10:59 AM .

Regards

Pete

Peter Coates said...

Hi MHalblaub [at 10/2/18 11:25 PM]

Thanks for
http://w3app.siemens.com/mcms/infocenter/dokumentencenter/cc/InfocenterLanguagePacks/SINAVY%20DC-Prop%20and%20SINAVY%20PERMASYN®/sinavy-dc-prop-permasyn.pdf

Indeed its very good on Siemens' motors.

I also found the explanation (pages 3 to 5) on how submarine propulsion works to be useful, especially the flow-chart.

Regards

Pete

Anonymous said...

Hi Pete

For a better understanding of structure of PERMASYN, its assembly drawing is introduced [3]. Judging from diameter of pipes or tubes for water cooling, volumetric flow rate of PERMASYN seems to be smaller than that of MAGTRONIC [1, 2].

[1] https://www.naval-technology.com/contractors/electrical/jeumont-electric/
In Sorpene submarine, silver pipe line connected three flanges for fuid (air, liquid) transport is on side wall of the motor. This silver pipe line is for water cooling. Diameter of pipe is bigger than tubes for water cooling in PERMASYN [2].

[2]http://www.ew.tu-darmstadt.de/media/ew/vortrge/greenenergyconversion/gec_8.pdf , page 8/20, left hand side picrue. 4 tubes for water cooling are set on the upper front of the motor.

[3]Ibid, page 8/22. Assembly drawing of PERMASYN

Regards

Anonymous said...

Hi Pete

My understanding of PERMASYN [1] for submarine is as follows.

[1] http://www.ew.tu-darmstadt.de/media/ew/vortrge/greenenergyconversion/gec_8.pdf
Page 8/22, from left side (stern side) to righ side (bow side)

(1)Sleeve bearing aka sliding bearing (or journal joint)
This bearing is most commonly used for ship or automobile engine. Its feature is silence and low friction.

(2)Bell-shaped rotor with permanent magnet
Magnet is fixed on metal (blue colored). Green part of rotor is fixed on shaft.

(3)Stator core
Stator is fixed on its housing. Stator core is water-cooled using two blue tubes.

(4)Shaft
Only left side of shaft supports heavy bell-shaped rotor, but, left end of shaft is supported by sleeve bearing (1). Right end of shaft is supported by floating bearing (through lubricant oil?), because weight distribution of rotor on the right side is small. To reduce peripheral velocity of floating bearing, diameter of right side of shaft is smaller than that of left side.

(5)Integrated converter
Converter housing is fixed in stator housing. Converter and stator is connected by electritial wires (omitted) through rectangular hole of converter housing. In this figure, water cooling is omitted. But, I think inner cylindical surface (and circular surface) is water cooled to absorb heat from permanent magnet.

Regards

Peter Coates said...

Hi Anonymouses [at 12/2/18 1:46 PM and 15/2/18 12:11 AM]

Thanks for the info and links.

I must admit I'm no expert on such highly technical matters.

Cheers

Pete

Anonymous said...

Hi Pete, continued from comment (15/2/18 12:11 AM)

On cooling of permanent magnet in ”(5) Integrated converter”.

Remanence [1] of permanent magnet decreases with increase in temperature [2] resulting in reduction of magnetic induction which is measure of performance of permanent magnet. For example, magnetic induction of Neodymium magnet at 80C is 90% at 100C, and reduced magnetic induction does not recover at temperature above 80C. Then cooling of permanent magnet was assumed in the previous comment.

By the way, China have successfully developed PMSM for submarine last year [3].


[1] https://en.wikipedia.org/wiki/Remanence
Remanence or remanent magnetization or residual magnetism is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed. It is also the measure of that magnetization.

[2] http://www.shinetsu-rare-earth-magnet.jp/e/design/words/t_c_b.html
The thermal coefficient of remanence generally has a negative value and the smaller the absolute value, the less the change of the remanence with temperature

[3] http://xjp.52hrtt.com/web/news_info.do?id=G1508913314551
(China's submarines test one of the world's top equipment, 2017-10-26 12:27)

Regards