IEEE Consultants' Network of Long Island

Belt Driven Lathes - John Dunn, Consultant Ambertec, P.E., P.C.

I took a trip down Memory Lane the other day. The journey began at

http://www.youtube.com/watch?v=ebDMh6pAlN8&feature=related

and continued at

http://www.youtube.com/watch?v=2sSXPC2AL_o  

which is where these belt driven lathe images came from:  

HYBRID POTPOURRI---Carl Schwab

OHM’S LAW FOR HYBRIDS: BER or regenerative braking is a direct way of recovering AND reusing brake energy normally wasted in heating the brake linings. The law simply states the motor must be sized upon braking requirement and acceleration desires. To make the greatest use of recovering the energy upon braking, the motor battery combination ALONE must be able to provide the acceleration.

MEETING THE GOVERNMENT FUTURE REQUIREMENTS---HOW?Jul 29, 2011 President Barack Obama delivered remarks on fuel efficiency standards for 2017-2025 model year cars and light-duty trucks during an event at the White House with the pontificating announcement of 54.4mpg composite(?). The puzzling thing is it didn’t really clarify anything. In particular it puts NO emphasis in improving LOCAL driving mileage-----apparently in the grand scheme it is insignificant in the government’s mind. SO no help can be expected in the development of an affordable SUV/VAN capable of 20—25 mpg for general urban usage. TOO bad! SUVs and VANs are the most popular vehicles with young families and 80% of the driving is LOCAL. 

AMAZING IMPROVEMENTS IN 5KW---200KW MOTOR SIZE—Carl Schwab

When the writer studied AC and DC machinery design at about 1950, the one thing we
did NOT have was the VVVF, (variable voltage, variable frequency) drives. Whether it
was AC or DC the motor fabrication was mainly slot and skein. Whether it was the field
or the armature, they were stacks of laminations with slots stamped into them for the wire skeins.

For power sources we had variable DC or 50-60 cycle AC, probably 3-phase. A variable
frequency source invariably was a DC motor driving an alternator as the generator.
Hardly convenient and frequently more complex to operate. If you really wanted a
variable speed drive, it would be a DC motor with various combinations of series and
parallel field windings used. We spent a LOT of time including lab work, separating iron
loss from copper loss from windage loss etc. to compute efficiency. Much of our design
study was to understand the theory of the motors and in the case of the AC machines
learning the various methods of starting under load etc.

 

NEODYMIUM SHORTAGE?--Carl Schwab

A neodymium magnet (also known as NdFeB, NIB, or Neo magnet), the most widely-used type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed in 1982 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet made. It is critical to the manufacture of PMSM motors for the PRUIS.

A few articles have appeared recently claiming that Toyota is actively looking for a replacement of the PMSM, (Permanent Magnet Synchronous Motor) which is very successfully employed in the PRIUS and other Toyota hybrid cars. Their suspected concern is that China will corner the world's supply of neodymium material for making the permanent magnets. Toyota is not alone in the worry.

RELUCTANCE MOTOR— Carl Schwab

RELUCTANCE MOTOR—
This is sort of "Something new under the sun", but not really. The reluctance type motor is similar but different from the well know induction motor and the nearly as well known PMSM, permanent magnet synchronous motor both of which are widely used in sizes ranging from 100 watt up to 500,000 watts.

Let's define reluctance as R=(amp turns)/[magnetic flux (in webers)]The R is usually in a script capital R. The only time I have ever used the reluctance formula was in the redesign of a relay armature. In the case of motors you can think of a reluctance motor as induction wound motor but with the rotor replaced with one of two types of rotors. The first is a smooth iron with strategically placed "flats" and the second is again smooth iron but with strategically placed embedded copper bars.

The upshot of this replacement produces a motor that has induction motor starting characteristic but with synchronous motor characteristics at synchronous speed. Not obvious other advantages that accrue are very high torque output and extreme rpm speed range when driven by VVVF (variable voltage variable frequency) drive. More about that later. Emerson Motor Co. call their offering SR for "switched reluctance" and build in standard NEMA frame sizes. Other companies offering reluctance motors are Swedish Emotron AB and Rocky Mountain
Technologies. SR motors don't do well direct-on-line, and are much better with an associated power converter to complete the package. Further the mechanical tolerances between the rotor and field windings are about 2 to 1 less critical than in either the PMSM or induction types of comparable size. Also the reluctance type motor can be more easily shaped into pancake or long cylinder type as end use requires.