Stator Winding Configurations

Electrical and electronic topics for small boats
alloyboy
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Joined: Thu Dec 24, 2015 8:15 pm

Stator Winding Configurations

Postby alloyboy » Sun Nov 19, 2017 11:04 am

[What are the advantages and disadvantages] of using a three-wire Wye-configuration stator versus a Delta-configuration stator in a permanent magnet electrical generation system?

I have searched the internet high and low can find many references to the two types but nothing that explains the benefits of one configuration over the other.

Do you know which configuration is used in an Evinrude and Johnson?

Just curious. Thanks.

jimh
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Location: Michigan, Lower Peninsula
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Re: Stator Winding Configurations

Postby jimh » Sun Nov 19, 2017 12:55 pm

I believe that in the larger horsepower engines the stator coils are wound with three sets of coils, creating three separate outputs. Those three outputs are separately rectified to DC. In conventional outboard engines with 12-Volts as the primary system voltage, the three DC outputs are wired in parallel, increasing the available current.

In modern Evinrude E-TEC engines the three DC outputs are controlled by the EMM to be wired in either parallel or series, depending on the engine speed range, in order to create the primary system voltage of 55-Volts.

Since the goal of the alternator on an outboard engine is to create a DC output, the notion of preservation of the AC phase is not particularly important. I do not know the precise phase alignment among the three coils on any particular outboard engine. The phase relationship between the coil windings would be determined by the physical location of the coils relative to the physical position of the permanent magnets that induce current into the coils. It could be that the phase of the AC output from the three coils is aligned in phase, or it could be designed for 120-degree phase spacing (or some other phase angle) between coils. I really don't know what it used.

The effect of the Y or Delta wiring may be more important in generation of AC power, particularly at a fixed frequency, as occurs when the engine running the generator runs at a fixed RPM. Since outboard engine power generation occurs over an extreme wide range of engine speeds, I do not see how the wiring of the alternator coils would have a particularly influential effect on the AC frequency and phase.

In interconnecting multi-phase AC power sources, the resultant voltages are affected by the wiring method. You see this all the time in utility generated power. Three-phase AC power intended for lighting and residential use is usually created so there is a 120V/240V relationship. Three-phase AC power intended for operating motors is often generated in a 208-VAC arrangement. There is a nice explanation with illustrations at

http://www.programmablepower.com/suppor ... bution.pdf

The above publication notes:

One advantage of a Delta configuration is that it does not have a neutral and therefore if a phase winding should fail the phase voltage at the load will remain constant.


Another good publication on this topic is:

3-Phase Power—Wye It Matters
https://www.belden.com/blog/data-center ... It-Matters

The above publication notes:

...we mainly see Delta used for any large motors or heaters that don’t need a neutral.