A131
DESIGN:
Electrotor-SloMo ~ Motor
Overview:
Slow turning electric motors that do not require a speed-reduction device between the motor's rotor and the aerodynamic rotor.
General Types:
Radial Flux Permanent Magnet [AFPM] motor; ~ Outrunner and Inrunner.
Axial Flux Permanent Magnet motor.
Transverse Flux Permanent Magnet motor.
Requirement for Electrotor-SloMo:
To be moved to its own page?.
Access, for hover w/ 300 GW etc. gives 6.0 hp by the momentum method and 4.1 hp by the blade element method. This is for a single rotor therefore the coaxial will be about 8.5 hp and 5.8 hp. This suggests 18 and 28 lbs / hp to hover.
The Flettner FL-282 had an effective disk area of 1,695 sq-ft and a gross weight of 2202 lbs, giving a disk loading of 1.3 lbs/ sq-ft. Somewhere it mentions 17 lbs / hp to hover.
To lift 300 lbs at 17 lbs / hp to hover (as per Flettner) will require 17.6 hp, which equals to 8.8 hp per motor, for the Intermeshing configuration.
The 3 lines below are also at the top of
1864.html
For 300 lb GW;
- 8.8 hp = 6,562 watts.
- Amps = watts / volts = 6,562/150 =
44 A per rotor.
Torque = 5252 * 8.8 hp/600 rpm = 77 lb-ft per rotor.
Target 10 hp to 13.4 hp (10,000W) for each motor.
Motor Calculations:
Motor Sizing:
The following is musing on my part, without any supporting information or calculations.
- The weight ratio of; engine + transmission / fuel is large. This is particularly so when the fuel tank is partially empty due to in-flight consumption and/or starting the flight with less fuel.
- The weight ratio of; motor / batteries is small. In addition, the weight of the batteries does not decrease during the flight.
- The above suggests that efficiency is more important when using a motor then when using an engine. Therefore whereas the engine should be operated just below it's maximum power setting the motor should operate somewhat above its optimum efficiency setting.
On the Intermeshing configuration the stagger will have to be increased if the F&P motor is increased from 36 coils to 72, to optimizes the motors power at a lower RPM.
- An alternative is to have more but smaller coils etc.
Inrunner vs. Outrunner:
General:
If all the specifications (parameters) of an inrunner and an outrunner were the same then I would think that the basic performance would be the same also.
Advantages of Inrunner:
There will be better cooling of the coils since the coils are spaced further apart due to the larger circumference.
The cooling fins of the laminates are spaced much further apart because of their large circumference and they are in a higher induced velocity region from the rotor blades.
The bearing(s) for the combined aero and electric rotors will have a smaller diameter and this will result in lower friction and a lower weight then that of slim-ring bearings.
The inrunning rotor can consist of a Halbach array. With a carbon composite backing frame the weight of the rotor will be lower.
The rotational inertia will be slightly less.
A bandage can be used to assist in retaining the magnets.
The expansion of the steel laminates will be outward and this will not reduce the width of the airgap.
Advantages of Outrunner:
Are there any?
The motor's rotor is outboard as is the aerohub?
Multiphase:
Advantages of Multiphase drives:
"Several advantages of high-phase drives have already been reported in the literature [4]-[6], such as: reduction of amplitude of pulsating torque and increased pulsating frequency easily filtered out by high-inertia applications; reduction of rotor harmonic currents; reduction of current per phase for the same rated voltage; and lowering the dc-link current harmonics. Higher reliability is also a very important characteristic of multiple-phase drives [7]. A high number of phases increases the torque-per ampere ratio for the same machine volume. A multiphase drive is likely to be limited to specialized applications where high reliability is demanded such as in EV, hybrid EV, aerospace, ship propulsion, and high-power applications in which the requirements are not cost oppressive when compared to the overall system. Even though a higher number of phases would yield a smaller magnetic yoke and decreased volume and weight, the number of poles is restricted physically to the PM area and the rotor diameter [8]. A high number of poles is required in the design of a high-torque low-speed machine. Several tradeoff fundamental electromagnetic design studies were considered before the construction of the present machine, which ended up having ten poles and five phases." ~ From; A High-Torque Low-Speed Multiphase Brushless Machine-A Perspective Application for Electric Vehicles
Notes:
The motor's cooling fan will consume some of the motor's limited available power.
A 6-part Article on Brushless Motors
: ~ Good Overview
Implementing Embedded Speed Control for Brushless DC Motors: Part 1 ~ The basics of brushless motor control
Implementing Embedded Speed Control for Brushless DC Motors: Part 2 ~ Brushless motor control using Hall sensor signal processing
Implementing Embedded Speed Control for Brushless DC Motors: Part 3 ~ Pros and cons of sensor vs sensorless motor control
Implementing Embedded Speed Control for Brushless DC Motors: Part 4 ~ 180 degree modulation for brushless motor control
Implementing Embedded Speed Control for Brushless DC Motors: Part 5 ~ V/f open-loop control in DC brushless DC motors
Implementing Embedded Speed Control for Brushless DC Motors: Part 6 ~ The use of vector control to control torque and flux
Permanent Magnet Motor Technology ~ more detailed. Have hardcopy.
Brushless Permanent Magnet Motor Design, Second edition Have hardcopy.
Outside Motor Manufacturers:
Motor especially built for the Thundergull: VERY similar to the Fisher & Paykel motor. It may be a F&P with modifications.
- Perhaps Rick was attempting to replicate this motor with the F & P development work. He would then have used it with mechanical reduction for the Main & Tail helicopter, plus for the hovercraft and for the outboard. This would explain why he had no interest in any development work in slow speed - high torque.
- Brushless motor BLDC 20 kW for electric plane, Test1
http://www.youtube.com/watch?v=PXI5d0Aws0Y
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The voltage for all was 11 V. |
RPM: |
Load: |
Amps: |
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295 |
none |
7.8 |
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325 |
none |
9.6 A |
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345 |
none |
9.8 A |
- http://www.youtube.com/user/forschungsbuero
- Thundergull eGull 2000 ultralight plane
http://www.youtube.com/watch?v=lEqz0rSZ0v8
- Earthstar Electric Gull 2000 at Arlington 2011. Powered by 72 Volt Rhino Lipos in parallel/series. Flies for 1.5 hours at cruise of 65mph. VNE is 120mph. The ESC is a prototype 500amp, so its much bigger than necessary. Motor is his own design 20-kilowatt motor. (for you RC'ers thats a 20,000 watt brushless motor!) The 36-coil, 42 magnet disk, weighing 16 pounds, is mounted on a truss arrangement behind the airplane's high wing, and drives a ground-adjustable pusher propeller. He built the motor from computer drawings by his designer, who then joined Mark for early testing and tweaking of the machine. Beierle reports pulling 217 Amps on takeoff, 211 in climb, and only 40 Amps at 55 mph. He has not used full power yet, but will after adjusting the pitch of the propeller to require more amperage for takeoff. Not sure on the total capacity. Designed by Mark H. Beierle. More info on Gull aircraft here:
http://www.thundergull.com/ on this particular plane here: http://blog.cafefoundation.org/ Enjoy!
- This brings up links to the above two, if needed. http://www.youtube.com/results?search_query=electric+thundergull&aq=f
- His home page;
http://www.forschungsbuero.de
- Translation of
http://www.forschungsbuero.de/html/elektromotoren.htm
- The picture of the motor shows 9 wraps per layer. The F&P Objective is/was to have 23 turns divided into 2 layers and the wire gauge is 14 AWG. See tests 20,21 and 22 in Access which are with the 14 AWG wire.
"Brushless DC motors (BLDC) are among the most efficient engines ever. Equipped with high-quality permanent magnets, they have a very high power density and efficiency of up to 95%. This makes them ideal for mobile applications such as electric bicycles, electric scooters, electric vehicles and even aircraft.
However, there is little series products on the market in the performance category of 5-20 kW. We fill this gap with our own developments. After a basic design study is the simulation of the magnetic field using a finite element program. On the computer then creates a virtual 3D model of the engine with a CAD program. Thus can be made directly to CNC manufacturing.
Our motors have the following features:
By the external rotor design combined with high pole a much higher torque produced as a conventional internal rotor motor.
The active materials (iron, copper) are utilized electromagnetically high. This means high performance and low weight. The supporting structure (housing, bearings) makes only a small proportion of the total weight. The engine consists almost entirely of active material (in contrast to many industrial engines, where weight is almost irrelevant).
In the design, great emphasis was placed on a rational and cost-effective manufacturing. The use of prefabricated plug-in coils is a major advantage over the winding by hand.
We have now constructed several brushless motors and a registered design protection in a special design.
References and projects carried out:
Development of a high-torque motor of 20 kW for the microlight eGull 2000 by Earth Star Aircraft, California.
Development of an engine for the e-glider configuration Desie ducks.
Electromagnetic design of a boat engine with 30 kW.
Motor bike for fast bikes Power: The motor is directly flanged to the disc brake mount the wheel hub, so that any wheel can be used. The capacity is up to 750 W, which is sufficient for speeds up to 45 km / hr. A utility model is registered, manufacturer requests are welcome!
In cooperation with the Smiles AG was the prototype of a new drive motor with about 5 kW of power for the City-El."
____________________December 26, 2011______________________
Joby Motors’ JM2 series, noting the even greater power and reasonable price. This would make a nicely-priced power package, with the motor at $1,299, the controller at $1,000, and the battery pack costing about $2,000. A $4,299 system (not including instruments and cabling) attached to a $10,000 airplane could give hours of inexpensive flying.
Joby Motor's
EMRAX motors
YUNEEC INTERNATIONAL:
Agni Motors:
ELECTRAVIA:
Geiger Engineering:
Kollomorgen :
Allied Motion - Emoteq: Currently this looks the best for full size craft.
Frameless brushless torque motors:
ETEL Inc.
Siemens:
Technologies M4:
Zytek:
UQM Technologies, Inc.
IDAM - INA Drives & Mechatronics
From bill111 at Eng Tips Forum
INA may have what your looking for all developed.
http://www.ina-dam.de/en/sub.php?page=16 Their main is impossible, but the link above should get you there (will these huge companies ever get a clue as to what the engineers need).
Read the descriptions carefully. They do have inside out brushless motors, of a fairly high power level.
Protean Electric
Radial Engine: Rotapower:
- If this engine can be supplied with output shafts at both ends then it might be (with rework) interchangeable with an electric motor with output shafts at both ends.
- For an engine that may be somewhat interchangeable with an electric motor see the Rotapower engine at:
Freedom Motors. Also see this sites web page; DESIGN: UniCopter ~ Engine
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Last Revised: Monday, December 30, 2011