1942

Item 1942

OTHER: Miscellaneous - Thoughtless Ideas - ELECTROTOR w/ Spherical Motor

Forget ~ The idea for pitch change will not work.

The alternating direction of the current past the ring of pitch PMs will not cause a tipping of the rotors.

Perhaps there is a way to overcome this flaw???

(Three-axis Torque Motor)

Overview:

A helicopter in which a single electric motor provides both thrust and cyclic control.

Sketch:

This is the same sketch as the one below except this one has been rotated 90º to show its orientation in the hub of a rotorcraft.

Note:

The parts 1 & 2, which are located above and below parts 3 & 4, are attached to the portion of the mast below the gimbal.
Parts 3 & 4 are attached to the aerodynamic motor with its rigid blades.

Application:

For small Unmanned Arial Rotorcraft where simplicity, low-cost, lightweight and quietness are important.

Possible secondary application, for lightweight manned rotorcraft.

Description of Operation:

Motor Configuration: An axial flux motor where the stator and rotor(s) are formed in a spherical shape.

Collective: For vertical climb and descent (thrust only) the controllers for all 3 or 4 segments will provide an equal amount of electrical power.

Cyclic: The cyclic flight-control system is by Weight-Shifting Hub. For pitch and roll the controllers for all 3 or 4 segments will provide a disproportional amount of electrical power which causes the motor's rotor and the aerodynamic rotor to pitch or roll a number of degrees.

Yaw: See notes on coaxial configuration below.

Idea for motor configuration; The copper windings (possibly, but not limited to 3-phase) will have a trapezoidal shape.

This force about the motor's Y and Z-axis might be created between the longer of the two unequal sides of the trapezoidal windings and the adjacent magnets. Concern: this electro-magnetic force will proved tipping of the rotorhead and it will relieve some of the loading on the spherical ball, however the electrical power that it consumes contributes nothing to lift is this a waist of energy?

A question; Does the proximity of a permanent magnet have any effect on the consumption of an alternating current that is passing through an adjacent coil. In other words does a motor with a PM rotor (which is freely turning ~ or ~ is stalled) draw more current than the same motor with the rotor removed?

The question relates to trapezoidal coils, as used in axial flux motors. The existing permanent magnets interact with the copper on the 2 long and equal sides of the trapezoidal coil. I would like to know if adding shorter magnets that interact with the copper on the longer side of the sides with unequal length (at the OD of the stator), and which are to apply a force at right angles to the existing magnets, will cause a faster consumption of the limited amount of battery power.

See section below 'Postings on the Subject of Power Consumption:'

Alternatively. Consider one controller for rotation about the vertical axis and replace the permanent magnets next to the longer of the two unequal sides of the trapezoidal windings with coils and their own 3-phase controller.

Convert the motor's X, Y and Z coordinates to those conventionally used to represent the body of the rotorcraft

This motor can be applied to;

Helicopters with various rotor configurations, such as bilateral rotors and single rotor w/ tail-rotor. Concern: This idea may not be viable for Intermeshing and Interleaving configurations since there is no hard linkage that will assure that the two rotors pitch in exact unison.

Helicopters with a coaxial configuration. This may be an ideal configuration. There would be two motors with the radius of all 6 disks (2 motors times 3 disks each) centered on a common gimbal. This will allow the motors to provide thrust, both cyclic and yaw control. It might eve be advantageous to have a large diameter hollow mast. For related information on this see; Electrotor - SloMo

Partially powered or jump-takeoff gyrocopter rotor.

Miscellaneous Notes:

Buy applying a downward thrust on the longer of the two unequal sides of the trapezoidal windings (used for pitch and roll control) this thrust will also unload a portion of the firction from the 2 rotational bearings and on the gimbal.

Three-axis Torque Motor: [Source ~ PMMT p.437]

Figure 9.16: Spherical three-axis motor with a PM rotor: 1 - armature winding, 2 - armature core, 3 - PMs, 4 - rotor core, 5 - shaft, 6 - spherical bearing. Courtesy of TH Darmstadt, Germany.

The three-axis torque motor can be designed as a PM or reluctance spherical motor. It can be used, e.g., in airborne telescopes. This motor has doublesided stator coils, similar to disk motors. There are usually slotless stator coils to reduce torque pulsations. The rotor can rotate 360' around the x-axis, and by only a few degrees in the y- and z-axis.

Fig. 9.16 shows an example of a three-axis torque motor, designed and tested at the Technical University of Darmstadt. The rotor segments cover a larger angle than the stator segments. The overhang ensures a constant torque production for the range of y- and z-axis movement - 10' for this motor (Fig. 9.16).

In designs with a complete spherical rotor three stator windings shaped as spherical sections have to envelop the rotor. The three windings correspond to the three spatial axes and are thus aligned perpendicular to each other. These three stator windings can be replaced with just one winding when the spherical rotor and stator have a diameter smaller than the diameter of the sphere, as shown in Fig. 9.16. The stator winding can then be divided into four sections with each section being controlled separately. Depending on the number of the winding sections activated and on the direction of the MMF wave, each of the three torques may be produced. The four inverters supplying the winding sections are shown in Fig. 9.17.

Owing to the spherical structure, the performance calculation of this type of motor is usually done using the FEM.

Figure 9.17: Four inverters supplying the winding sections of a spherical motor. Courtesy of TH Darmstadt, Germany.

Postings on the Subject of Power Consumption:

RC Groups ~ Aircraft - Electric - General ~ Electric Motor Design and Construction ~ Electrical power consumption

Rotary Wing Forum: http://www.rcgroups.com/forums/showthread.php?t=1297771

Summation: A STATIC magnetic field has no influence on current drawn in any wires in it's vicinity..apart from a few specialized materials whose resistance changes in a magnetic field.

Note:

The performance, simplicity and weigh of the craft my be further improved by the use of Sensorless Controllers

Searches:

US Patent Applications:

"Spherical Motor" AND (helicopter OR rotorcraft) - 1 hit. Not applicable

"Three-axis" AND "Torque Motor" AND (helicopter OR rotorcraft) - 3 hits. None applicable

See three US patents noted at the bottom of this web page. Design, Modeling and Control of A Spherical Motor

5,319,577, 5,410,232, 5,402,049, Of no interest

US Patent Applications:

"Spherical Motor" AND (helicopter OR rotorcraft) - 2 hit. Neither applicable
"Three-axis" AND "Torque Motor" AND (helicopter OR rotorcraft) - 3 hits. None applicable

Google:

"Spherical Motor" - 12,900 hits

"Three-axis Torque Motor" - 278 hits

"Spherical Motor" AND (helicopter OR rotorcraft) - 200 hits

Design, Modeling and Control of A Spherical Motor

"Three-axis Torque Motor" AND (helicopter OR rotorcraft) - 1 hit - Rotary Wing Forum

Related Page:

DESIGN ~ Electrotor-SloMo - Control Flight - Cyclic by Sectored Torque-Pitch - Overview

Initially displayed: August 25, 2010 ~ Posted to Rotary Wing Forum: August 24, 2010 ~ Posted to RC Groups: Aug 25, 2010 ~ Last Revised: September 1, 2010