T-Pain Is On A Boat: Re: [Electric Boats] Magnetic Circuits & The Prototype Motors

Hi to whoever reads this and Kevin, Ive appreciated your comments the last couple of years that Ive been a member of this group.

Anyone out there have any experience with Halbach Array BLPM motors and suitable controllers? I want to play around with a large diameter motor/rotor for use in propulsion (on land)
As a consulting design engineer, I've found that being able to look at a problem from many points of view is helpful in finding the right solution. Too many engineering graduates are so specialized that they find it difficult to see around the corner. My college degree is in Industrial Design, and my experience crosses a few areas of specialization, so I can communicate those languages as needed, but when I analyze the information it is with eyes and ears wide open.

--- In electricboats@yahoogroups.com, Kevin Pemberton wrote:
>
> Hi Roger,
>
> Although I went to the groups page to unsubscribe seems I didn't do the
> job right. It allowed me the opportunity to see this thread. So I
> respond and stay with the list till those that want to respond to my
> comment have that chance. Of course this effort may be in vain because I
> don't know if I can still post to the group.
>
> Roger all people are in fact classified. They are either classified as
> ambitious or as a slacker of sorts. It is best to simply state that an
> engineer may be an inventor but it is more likely he is not, he is an
> engineer. An inventor has set the standard for vision and drive above
> that of most engineers. In fact his lab is likely full of engineers of
> all levels that do the work of developing of the inventors vision, by
> request of the inventor, whom manages the team from some top tear. The
> inventor need not be an engineer but it helps him if he understands the
> language of his team. The level of managers that remove the inventor
> from the team is based on his understanding this language. If he does
> not speak the lingo he/she will need to have translators to instruct the
> engineer.
>
> Either way it is important to understand that the number of disciplines
> required to engineer a motor requires many hats. This discussion will
> illustrate that point for me. For the person that asked about anyone
> thinking of using aluminium or other metal as the core on a motor should
> have had the answer "Yes". This would best be described by example.
> Voice coils(a motor) are used to run the head of many hard drives as
> well as speakers to a beat or to the location on the hard drive to
> retrieve or write data. The speed the motor reacts is based on the
> amount, if any, of steel used in the motor so in many cases it is not
> used. My use of the term steel in place of iron was intentional as the
> properties of the mix(alloy) determines the magnetic properties of the
> core. Not using a metal core is used for fast acting servos and motors
> but not in applications such as the traction motors we need to use in a
> boat.
>
> The core of the motor serves as a flux guide nothing more. if we guide
> the magnetic flux we can obtain more work thus increasing efficiency
> over an air core depending on intended use. The more flux that makes it
> to it's intended location, the more work. This tunnelling has a
> disadvantage. When we turn the winding on we first must overcome the
> resistance of the core to charge or change as it were(overcoming this
> resistance is lost energy). The size of coil and energy required to
> overcome this resistance is higher than would be needed if we could use
> an air core for the job. As I have stated in the past all things built
> have compromises. When the core becomes fully charged we say the core is
> saturated. The better we control the power to the coil, the lower the
> temperature of the coil after the core is saturated, and we no longer
> need to overcome it's resistance.
>
> What we use for a core depends on the speed we want the motor to react.
> Modern transformer laminate allows transformers to achieve 98%
> efficiency. The higher the count of laminates per measure, the lower the
> eddy current and higher the efficiency because this one loss is reduced.
> In all honesty? The efficiency of the modern motor is quite an
> accomplishment. This modern efficiency was not however spurred by the
> motor industry. Competition spurred keeping things as they were rather
> than efficiency. It was government mandate that changed the way motors
> were being built. Now that the ball is rolling, and the customer has
> come to demand efficiency, competition has been developed in better design.
>
> I feel that Hall effect cogging and controllers that take advantage of
> such feed back are likely to save more energy in DC motors than further
> development of cores within the motor. Modern engineering practice is to
> design using off the shelf black boxes. Anything other than that is to
> re-invent the wheel. pun intended. Consider that a Prop is most
> efficient when positioned parallel to the boats motion. A prop with the
> least number of blades is most efficient because it lowers drag(making
> the number of poles low if a wheel motor were developed). Attachment of
> a nozzle to the prop blades so more poles could be incorporated in such
> a motor has proven inefficient and is also one of the reasons a Kort
> nozzle is not attached to the prop. Magnetic sludge I had not thought
> of, but this is just another reason not to re-invent. Wheel motors are
> large Diameter and would increase the angle of the prop to the horizon
> if gearing were not used. As stated earlier this would have a negative
> effect on overall efficiency of the design.
>
> If I were to prototype a motor. I would likely incorporate a bulb on the
> front of the boat that contained the motor. This design I would take
> from the cargo ships as it has saved many barrels of fuel. From this
> bulb I would extend the prop shaft aft only enough to reduce the
> turbulence from the bulb. I would encase the shaft to reduce resistance
> from the shaft turning in the water. I would pressurize the bulb to keep
> water out of shaft and motor housing as is done on ROVs. The motor would
> be a wheel motor with control scavenged from a floppy or hard drive
> modified for the power requirements of a larger traction motor. This
> would allow for timing of power based on rotor angle, thus saving the
> need for brush maintenance, and offer pulse timing based on rotor
> location. The bulb would allow for proper positioning of the prop to the
> horizon, and the prop I would placed within a Kort nozzle. Torsional
> strength would still be required over a larger area of the boat and
> ballast would need to be added to overcome the weight in the front of
> the boat. Higher voltages would be used to overcome conductor length
> needed for motor placement and batteries would likely be the above
> required ballast. If one were to design a stringer for the required
> torque requirements they may be able to incorporate a battery box within
> it.
>
> Anyhow it is better to design considering how much gain can be obtained
> with each component in the completed project. Some parts of a
> motor/control system should be improved for efficiency. combining the
> two items in seamless harmony would be the best advancement. Hull design
> to improve the dynamics of the drive system would make big strides in
> electric drives. Low maintenance motor design would make access to
> maintain the motor less of an issue. Our problem is we don't look at
> boats as one unit, but many.
>
> There got it off my chest.
>
> Kevin Pemberton
>
> P.S. My apologies go out to anyone that could not find the unsubscribe
> link at the bottom of list emailings. Sometime during the course of
> scanning all posts, I found it easier to drop the HTML formatting(I
> chose straight text). I had not paid attention to the fact that doing so
> dropped those links from the page. If you are wanting those links in the
> future, and you have turned off HTML formatting, just turn it back on
> and the links will re-appear.
>
> On 01/06/2013 08:10 AM, Roger L wrote:
> >
> > It's interesting that you should bring up professional accreditation.
> > Many schools are accredited, but there is another level..... The
> > national exams for a person to be an professional engineer - a PE
> > - are still a true test of ability. That will be slower to change.
> > Professional tests are heavy into theory, math, and hand-worked
> > solutions. So far I can't see that a computer technology based
> > education stands a chance of teaching the depth of knowledge required
> > to pass those professional tests. And if someone can, then good for them.
> > And frankly most of what is now seen as engineering work doesn't
> > require that level of expertise. All it needs is a good background in
> > basic science and a good modeling program. The good modeling
> > programs give the modeler control over the materials and geometry
> > while the program does all the calculations of things like current
> > flow and interacting fields - and automatically includes the higher
> > education stuff like eddy currents and edge effects that used to be
> > mind-numbing to calculate. That's been a game-changer.
> > I'm guessing we will see engineering break into different levels much
> > like the medical profession has done recently.
> > Roger L.
> > *From:* Myles Twete
> >
> > *To:* electricboats@yahoogroups.com
> >
> > *Sent:* Saturday, January 05, 2013 11:51 AM
> > *Subject:* RE: [Electric Boats] Magnetic Circuits & The Prototype
> > Motors
> > So it's both: The educational system moving away from
> > student/instructor interactions combined with the student's
> > unwillingness to put in enough time to be sure to learn the
> > fundamentals. And given that online courses allow students to
> > submit all work electronically, there's absolutely no assurance
> > that the student did ANY OF THE WORK that was submitted.
> > Accreditation organizations should pay attention to this...
> > MT
> >
> >
>
>
> --
> Committing murder in exchange for lifestyle
> makes you a "thug" not a "Rights Activist"
>