people are misled by labels so my hi-skool fizziks prof always made it a point when referring to motor/generator diagrams as mogen.
madin88 said:Luke has explained the thing with the torque already plus he described an experiment. PLEASE DO IT!!!
Left tooth:
x-component: 9.67603e-012-I*4.68351e-012 Tesla meter^3
y-component: 8.69034e-011+I*7.40813e-012 Tesla meter^3
Right tooth:
x-component: -3.31067e-011+I*9.42613e-012 Tesla meter^3
y-component: 3.25291e-011-I*5.01319e-012 Tesla meter^3
madin88 said:The point is that you simply cannot compare a wound teeth from a stator with a normal coil, because only the magnetic force (or field lines) which are moving the rotor play a role for the mechanical power, the other fields are cancelling out.
madin88 said:Thus, the Endturns do nothing in terms of that.
JanComputerman said:Build it and it will spin!
Buk___ said:With respect -- and I've tried very hard to show everyone here respect, even the male member that did his utmost to derail this thread right up to the point his ad hominim attacks turned into a puerile attempt at character assassination,
Your statement above gives me nothing to argue against. It offers no evidence, no analogy, no physical or mathematical basis.
It is un(dis)proveable, unrefutable; and unratifiable. In short, it is undeniable...
It is your opinion and you believe it.
But I didn't come here to prove this to anyone else, I came to see if anyone could dissuade me from the conclusion I was (and then had) reached.
Miles said:Martyn,
This is from: Mechanical Design of Electric Motors - Tong, Wei. (Page 242 & 243). CRC Press.
"4.4.5 Stator Winding One of the important parameters in stator winding is the slot fill ratio, which is defined as the percentage of the space occupied by magnet wires to the total available space of the slot. In order to lower the wire resistive loss and increase the power density, it is highly preferable to have the maximum copper fill, that is, maximum slot fill ratio. A winding end turn refers to the amount of the winding extending beyond each end of the stator’s magnetic core structure. Though the end turns are necessary to complete the electrical path within the winding, they contribute little to the motor torque output. Motor torque is only generated by the winding that lies within the stator’s magnetic core structure. Consequently, it is highly desired to minimize the length of the winding end turns. This can not only save the wiring material and lower the material cost but also reduce the copper loss and increase the motor efficiency. The shorter the winding stack length, the greater the impact of the end turn length on motor efficiency."
"Wei Tong, Ph.D, PE is chief engineer at Kollmorgen Corporation, a subsidiary of Danaher Corporation, Radford, Virginia, USA. He is an internationally recognized expert on mechanical–electrical–thermal systems. A fellow of the American Society of Mechanical Engineers and a registered professional engineer in the state of Virginia, USA, Dr. Tong holds 28 US patents and 16 foreign patents. He presently serves as an associate editor of ASME Journal of Heat Transfer and International Journal of Rotating Machinery.
As a fellow (2006–) of the American Society of Mechanical Engineering (ASME), Dr. Tong has served on several ASME committees, including Heat Transfer under Extreme Conditions (K-18), Heat Transfer in Energy Systems (K-6), Aerospace Heat Transfer (K-12), and Long Range Directions and Issues in Heat Transfer (K-2). He was the chair of the K-18 Committee during 2006–2009. In 2006, Dr. Tong was appointed as an adjunct professor in the Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, where he taught an undergraduate course on mechanical engineering design."
Voltron said:"My motor design --such as it is -- combines two motors in a single hub, each with different characteristic, and linked by a planetary differential. Not a unique idea by a long chalk, but one that -- to my knowledge and research, has never been successfully built."
Not to diminish your research, but that type of system is already in use, the NSK wheel motor for cars, and the Solomon Technologies drive system for boats being two examples..
NSK-wheel-hub-motor.jpg
nsk.jpg
solomon.jpg
I'm not sure if the NSK counts as a planetary. but the Solomon setup def has one in between the two pancake motors... i.e. its not simply two motors coupled to a common shaft.
madin88 said:About the simulation:
Yes the vertical field lines (which should be the one important for the torque) look larger as on the left picture, but the numbers below are more confusing than meaningful (at least for me).
Yes. It might (for example) be a slice taken as shown in red in this inrunner model:, but could equally well be an outrunner; or of any order.major said:Buk,
EndLoopsFEA.jpg
Is this a cross section of a single tooth, the plane of which is perpendicular to the radius of the motor?
major said:It also appears some of the field lines cross other field lines. Please comment how that happens.
Miles said:Hanselmann 1.jpgThis is from Hanselmann "Brushless Permanent Magnet Motor Design" page 209
"Motor constant as given by (9.11) ignores the winding end turns. Since the end turns create ohmic losses but do not produce torque, they directly diminish motor constant."
That would also likely increase motor size per watt of power capacity (and per foot-pound of torque) due to the loss of packaging efficiency.Buk___ said:Imagine this. The shortest way (reducing ohmic losses) to enclose the greatest area (to prevent saturation) would be to use round BLDC stator teeth.
billvon said:That would also likely increase motor size per watt of power capacity (and per foot-pound of torque) due to the loss of packaging efficiency.Buk___ said:Imagine this. The shortest way (reducing ohmic losses) to enclose the greatest area (to prevent saturation) would be to use round BLDC stator teeth.
Buk___ said:(BTW: Did I hear that damn buzzing sound again somewhere?)
Buk___ said:He excludes the ends turn from the formula he derives, because he believes they are bad.
Buk___ said:I get that if its in a book, it is hard to argue against, but books have been wrong before.
Buk___ said:Note: The intent here is to combine two smallish 100mm/120mm geared hub type motors in a single hub to provide the equivalent of a '201 wind' and a '328 wind' in a small, stealthy and economic package. Good climbing ability and descent top speed without a ton of weight, huge battery requirement or thermal issues at either end of the scale.
Buk___ said:
major said:What does "or of any order" mean?
major said:In the flux map of the cross section which you show, the flux lines in the tooth which would run radially in the motor and cross the air gap will be oriented perpendicular to the viewing screen.
major said:What information is displayed on the map concerning the B (or H) field in the tooth?
major said:If I understand your analysis it involves only a single piece of a single tooth and some wire (with current). I can see there are x & y dimensions to the tooth, what is the z dimension?
major said:Doesn't the entire magnetic circuit or at least whole symetrical section of it need to be modeled to obtain magnetic behavior in any part?
JanComputerman said:This is some of what I know ...
Gearing = losses ... Avoid gearing!
More core material = more core losses
If your motor is only in the high 80's % efficient then two of them with gearing is going to lower the total efficiency and most likely raise the cost i.e. two controllers for two motors.
liveforphysics said:Turning slow doesn't mean inefficient.
liveforphysics said:The forces end turns make on the tooth are in equal and opposite thrust-axis orientations on the rotor so they don't contribute towards rotational torque in the axis we care about for vehicle motion.
liveforphysics said:You can easily show this by winding a tooth that has end-turns that hang down however many feet away from the motor you wish, and it makes no difference in phase amps per amount of torque (but does increase copper loss).
Alan B said:It is unfortunate that the simulator has a curve called "efficiency", since it continues to confuse people, and be mis-interpreted. ...