Patent Application
20130187586
The disclosed inventions relate to the field of direct energy conversion and the production of mechanical torque from the utilization of an electric current, and to the field of electric motors and to utilization of direct current as a “motive force.” The disclosed inventions also relate to the field of power conversion devices which transform electrical power into rotary mechanical power.
Some disclosed embodiments relate to a class of motor having multiple stator and rotor sections, such that each rotor section is associated with a specific stator section, although attached to a single output shaft, The lateral axis of each rotor section may be disposed at an oblique angle with respect to the axis of the common shaft, and angularly displaced in accordance with the number of rotor sections employed, for example: 90 mechanical degrees for two rotors, 120 degrees for three rotors, etc.
Some disclosed embodiments also relate to multiple motors having two or more motor sections, operating in parallel, each of which is comprised of a stator having two or more salient poles, and a rotor geometry devoid of coils or windings of any kind, affixed obliquely to a motor output shaft, and so disposed as to ensure a constant air gap between the rotor body and the salient poles of an associated stator section.
Some embodiments of the invention also relate to multiple motor sections with their associated armatures, mechanically positioned out of phase with one another, but mounted so as to allow the output pinions of each individual motor to impinge upon a common output gear, of larger diameter, mounted upon a separate but common output shaft, such that each individual motor's output is combined mechanically, and afforded an amplification of torque.
Some embodiments of the invention also relate to a single motor having a stator section with salient poles, and a rotor geometry devoid of windings, affixed obliquely to a motor output shaft, and disposed as to ensure a constant air gap between the rotor body and the salient poles of the stator section.
Some embodiments of the invention relate to a switched reluctance D.C. motor motor having a stator section with salient poles, and a rotor geometry devoid of windings, affixed obliquely to a motor output shaft, and disposed as to ensure a constant air gap between the rotor body and the salient poles of the stator section
Notwithstanding the increased interest in energy conversion over the recent decades, no substantial advances have been made in increasing the conversion efficiency of electric motors. Rather, the art has made incremental advances relating to improved magnetic materials, more powerful permanent magnets, and sophisticated electronic switching devices. Such improvements, at best, relate to very small increases in overall efficiency, usually gained at very considerable expense.
Patents in this area include: U.S. Pat. Nos. 2,917,699; 3,132,269; 3,321,652; 3,956,649; 3,571,639; 3,398,386; 3,760,205; 4,639,626 and 4,659,953. Also in this area are EPO patent no. 0174290 (March 1986); German patent no. 1538242 (October 1969); French patent no. 2386181 (October 1978) and UK patent no. 1263176 (211972).
The basic concept employed in earlier motor art is the interaction between a current carrying conductor(s) and a magnetic field of some kind. This fact is true regardless of motor type. This basic concept appears in DC motors, single phase AC motors, poly phase induction slip motors, which utilize a rotating magnetic field, and in poly phase synchronous Motors with externally excited electromagnetic cores, or permanent magnet cores as the case may be.
Other types of designs may he found, for example, in the design of stepper motors, which utilize a magnetic “ratcheting” action upon magnetic material in the armature, in response to applied pulses of current, and various types of reluctance motors in which the rotor moves with respect to a salient pole piece, experiencing a large variation in air gap during its motion. But, these devices typically do not have a constant and continuous air gap of fixed dimension between the rotor and the stator.
The prior art has not produced a multiple phase, multiply segmented stator with individual, obliquely disposed, laminated armatures devoted to each stator section, such that each stator/rotor combination employs a continuous air gap of constant dimension, regardless of the elliptical profile of said armatures, but not employing any current carrying conductors, coils, windings or bars within or upon the armatures, as a means of producing torque upon the output shaft.
Nor can it be said that the prior art has arranged such motors to cooperate in “parallel fashion,” through a reduction gear arrangement so as to provide an amplification of torque while sharing the mechanical load.
A previous example exists, which describes an alternator having a single rotor canted at an angle, and makes use of the unique rotor design featured within this disclosure. Said rotor was introduced in the power conversion device entitled “Alternator Having Improved Efficiency,” which was invented by James F. Murray III, filed as application Ser. No. 07/112,025, on Oct. 21, 1987, and later granted U.S. Pat. No. 4,780,632 on Oct. 25, 1988, and is herein incorporated by reference.
There are marked differences between the presently disclosed inventions and the inventions disclosed in the “Alternator Having Improved Efficiency,” patent (“the Alternator Patent”). A few non-limiting examples of which are listed as follows:
1.) Alternator of the Alternator Patent can be operated as a motor only when used in conjunction with the basic motor concepts described herein (i.e., requires field flux and current-carrying conductors).
2.) Alternator of the Alternator Patent does not require salient pole projections in order to operate.
3.) Alternator of the Alternator Patent makes use of an electromagnetic field winding, or a permanent magnet as its source of magnetic flux.
4.) Alternator of the Alternator Patent does not require a shaft position indicator, or a commutator of any kind in order to function.
5.) Alternator of the Alternator Patent does not require a position sensitive, electronically controlled, pulsed power supply, in order to generate electricity.
Other similarities between the Alternator Patent and the presently disclosed inventions include elements possessed by most rotating power converters, such as bearings, shafts, end bells, laminations, mechanical housing, etc.
As evident from the above discussion, electric motors have been in use for well over 100 years, and they exist in several forms. While, the basic concept has not substantially changed, the manner in which the switching of supply current is controlled has evolved. However, existing motors typically experience performance limitations due to the manner in which Back EMF and inductive field energy are treated. The generation of Back EMF in motors of all kinds is chiefly due to two things: the movement of conductors through a magnetic field, called Speed Voltage, and the rate of change of current through a winding, called Transformer Voltage. Conventional wisdom suggests that Speed Voltage Back EMF is totally unavoidable, and in fact, is necessary for the transformation of electrical power into mechanical power in a typical motor. However, one drawback of Speed Related Back EMF is its parasitic nature that serves to degrade the potential supplied to the motor from an outside source (i.e., the source voltage).
The parasitic nature of Back EMF arises from, among other things, the mistaken assumption that Back EMF is required to produce torque. This, in turn, leads to design compromises which must be made in order to implement traditional electrodynamic machine geometries. Consider, for example, a conventional DC Motor consisting of a stator with salient field poles, and a rotor-armature with a self-contained commutator. Application of a DC current to the rotor leads produces a rotary motion of the rotor (i.e., motor action). However, the rotation of the rotor conductors in a magnetic field also induces a voltage in the conductor that opposes the current applied to the rotor leads i.e., generator action). These facts actually demonstrate an important aspect of conventional machines; if standard design parameters are always followed, then any motor must perform as a generator while it is running, and any generator must perform as a motor while it is in operation. The explanation of this similarity is because both machines are dependent upon the same basic geometry for their functionality, and so, both motor and generator action occur simultaneously in both devices.
The above-described basic geometry of a conventional Speed Voltage based system results in the production of parasitic Back EMF as follows. In a Speed Voltage based system, the magnetic flux must interact with an electrical current-carrying conductor (e.g., rotor windings), thereby producing a mechanical force that generates a torque to turn the motor shaft (i.e., a motor action). The subsequent motion of the conductors through the magnetic flux produces a relatively high Back EMF (i.e., acts in opposition to the torque producing current) due to the motion of the conductors with respect to the magnetic flux (i.e., a generator action). In order to continue normal operation, and establish electrical equilibrium, any motor that produces a Back EMF having a constant average value, must draw down on the line-potential in order to overcome the effects of this parasitic Back EMF voltage. Thus, this process of source potential degradation due to Back EMF requires the input of considerable energy from the source in the form of a voltage in order to maintain normal operation.
Another design factor of conventional Speed Voltage dependent machines is that, typically, as the rotor turns from pole to pole the air gap between the rotor and the stator will vary in width (from a smaller gap when the rotor is “facing” a stator pole, to a larger gap when the rotor is “between” stator poles). This change in the air gap results in a change in the magnetic potential energy within the air gap resulting in the Back EMF component described above. These and other significant issues and inefficiencies persist in traditional DC motor designs.
Before turning to the improvements and advantages of the disclosed inventions, a brief review of some fundamental concepts for electric motor operation is instructive. The basic premise is that the force developed by a current carrying conductor immersed in a magnetic field is described as (equation 1):
F=BlI,
where, F is the force developed, B is the flux density, l is the conductor length, and I is the current. This simple equation suggests that a current-carrying conductor situated in a magnetic field will experience a force that is directly proportional to the applied current, the flux density and the length of the conductor. This principle underlies the operation of the millions of electric motors spinning every day in locations all over the world.
The voltage produced by a conductor moving through a magnetic field can be described using (equation 2):
V=Blv,
where, V is the voltage developed, B is the flux density, l is the conductor length, and v is the tangential velocity of the conductor as it rotates. Accordingly, if a conductor is moved through a magnetic field by an external motive force (e.g., a prime mover), then the voltage produced may give rise to a current in the conductor, and such a device exhibits generator action. Conversely, if a conductor is carrying a current, and thereby moves through a magnetic field under the influence of the current itself, the device exhibits motor action. However, in the act of moving through the field a voltage is produced within the conductor accordance with equation 2, and acts in such a manner as to diminish the applied current responsible for the conductor's motion, and this produced voltage is typically referred to as a Back EMF.
Examining the actual power present in the system can be accomplished as follows. Mechanical power can be expressed as the product of Force and Velocity. Velocity is therefore missing from the first relationship (equation 1), but it can be included by multiplying both sides of equation 1 by the additional parameter:
Fv=BlIv.
The resulting expression now denotes a form of mechanical power expressed as (equation 3),
Pm=BlIv,
where, Pm denotes mechanical power.
In similar fashion, the voltage expression (equation 2) denotes only potential, not power. Electrical power can be expressed as the product of voltage and current. Current is missing from the second relationship (equation 2), but it can also be included by multiplication to both sides of the equation:
VI=BlvI.
The resulting expression now denotes a form of electrical power as (equation 4),
Pe=BlvI.
Note that BlIv (equation 3) is equal to BlvI (equation 4), and therefore, Pe must be equal to Pm. This analysis is as expected, and holds with current theories that stipulate the applied power is equal to the output power minus the system losses.
Another important factor to consider is the magnetic flux in a DC motor. The flux, Φ, can be expressed as (equation 5):
Φ=LI,
where L is the inductance and I is the current. Taking the derivative of the flux expression with respect to time, t, yields:
dΦ/dt=d(LI)/dt.
Substituting V for dΦ/dt gives (equation 6):
V=LdI/dt+IdL/dt.
The first term in equation 6 is the product of inductance (L) and the rate of change of current (I) with respect to time (t). This is the previously discussed Transformer Voltage Vt. The second term is the product of the current (I) and the rate of change of Inductance (L) with respect to time (t). This is the previously discussed Speed Voltage Vs. Thus the relationships for each Voltage type is:
Transformer Voltage (equation 7),
Vt=L dI/dt, and
Speed Voltage (equation 8),
Vs=I dL/dt.
Expressing Vt and Vs in terms of the energy can be accomplished as follows. The field energy, Pt, due to the Transformer Voltage may be expressed as follows:
Pt=IVt.
Substituting for Pt and Vt gives:
dE/dt=IdΦ/dt.
Simplifying to (equation 9):
dE=IdΦ.
Equation 9 expresses the quantity commonly referred to as the reactive energy. The dissipative energy for the system can, likewise, be expressed as follows, Starting from equation 8, Vs=IdL/dt, and realizing that L=Φ/I, then L=Φ(I−1), and dL/dt=ΦI−2dI/dt.
Substituting (ΦI−2)dI/dt for dL/dt=gives:
Vs=I(−Φ/I2)dI/dt. Multiplying both sides of the equation by I yields an expression for dissipative power, Ps. But, VsI=dE/dt, therefore, Ps=dE/dt=−ΦdI/dt, and (equation 10):
dE=−ΦdI.
Combining equation 9 and equation 10 the total energy in an air-gap is (equation 11):
E
I
=IdΦ+ΦdI.
The energy relationship described in equation 11 can be further explained with reference to
Em=IΦ.
The region 110 above line 100 indicates the (I dΦ) reactive energy region and region 120 below line 100 indicates the (Φ dI) dissipative energy region.
The relevance of this energy relationship can be further explained with reference to
Referring now to
For illustrative purposes, the following four calculations using equation 11 can be made representing the component energies associated with each air gap size (g1 and g2).
For a gap size g1: Φ1dI=(13.5)(18−12)=81 Joules, and I1dΦ=(18)(15−13.5)=27 Joules. For a gap size g2: Φ2dI=(15)(18−12)=90 Joules, and I2dΦ=(12)(15−13.5)=18 Joules.
Thus, each energy component has a different value, but much more interesting to note is that the total energies E1 and E2 which represent the energy for air gap sizes of g1 and g2, respectively, are equal (27+81)=(18+90)=108 Joules. This is consistent with the understanding that the motor shaft energy and motor input energy are equal in a motor of standard design, and co-exist within the motor structure. Hence, the term co-energy.
In further illustration of conventional DC motor operation, consider the following example of normal, Speed Voltage dependent operation. As depicted schematically in
Accordingly, if the proper voltage is applied to the motor terminals, and the mechanical load does not vary, the above properties should prevail indefinitely after thermal equilibrium has been reached However, this same example DC motor will have drastically different properties upon first being started. This is illustrated by the diagram in the second diagram in
At the instant illustrated, the DC motor has not yet begun to rotate, and there is no Back EMF, but the starting torque is relatively large at 637.986 in-lbs, which is 5.165 times the running torque. The Back EMF that develops as a function of the motor's increasing rotational speed reduces the start-up current of 135.965 amps down to the full load ampere (FLA) value of 26.326 amps. This “high start-up current,” behavior is standard and expected in conventional Speed Voltage dependent motors.
Bearing these facts in mind, it stands to reason that for two, otherwise-identical, electric motors, the one that employs a larger, or surplus, number of winding turns per pole would experience a comparatively higher inductance L, and correspondingly, a relatively higher total Back EMF, resulting from the sum of Vs and Vt. Accordingly, to avoid this occurrence, it is typical in the prior art of electric motor design that the winding turns per pole are generally kept to a minimum, for a given operational voltage, thus allowing the Speed Voltage component to drive the design criteria, and minimize the Transformer Voltage component.
However, this engineering trade-off, of keeping inductance L low by using fewer windings, diminishes the amount of stored energy in the motor's magnetic circuit, and causes motor performance to he tied to the characteristics imposed by the Speed Voltage component of the Back EMF, most notably, the requirement for a higher magnitude source voltage and reduced torque output. Other motor design drawbacks and Back EMF issues also exist in prior systems.
An electric motor is disclosed, some embodiments having a motor segment having a stator, having stator poles and stator windings and a rotor having a flux path element. For some embodiments, the flux path element is attached to a rotor shaft at an oblique angle to the longitudinal axis of the shaft. The flux path element has a shape that provides a uniform constant air gap between it and the stator poles when the shaft is rotated.
An electric motor is disclosed, some embodiments having a plurality of motor segments, each segment having a stator, having stator poles and stator windings and a rotor having a flux path element. For some embodiments, the flux path elements are attached to a rotor shaft at an oblique angle to the longitudinal axis of the shaft. The flux path elements have a shape that provides a uniform air gap between them and the stator poles when the shaft is rotated. The rotor shafts of said motor segments are mechanically coupled to each other.
In an embodiment, the flux path elements comprise a silicon steel lamination stack or a solid ferrite plate. In a further embodiment, the motor has a shaft angle sensor and a motor controller, and the motor controller receives a shaft angle from the sensor and supplies current pulses to the stator windings according to the shaft's angular position signal.
In a further embodiment, the stator poles are positioned in pole pairs with the rotor and rotor shaft between them and form isolated stator magnetic field circuits when the stator windings are supplied with electrical current, such that a magnetic field is established having a single magnetic polarity in each of the poles of said pole pairs, with each pole of the pole pairs having opposite magnetic polarity. In further embodiments more than two poles are installed in each stator section.
In a further embodiment, the rotor flux path elements have a shape defined by the volume contained between two parallel cuts taken through a right circular cylinder at an angle other than 90 degrees with respect to the axis of symmetry of said cylinder, each flux plate element having front and back faces that are substantially elliptical, and having major and minor axes. In an embodiment, the flux element angle with respect to the axis of symmetry is substantially 45 degrees. In an embodiment, multiple rotors are attached to a common shaft, or independent shafts coupled through a clutch or similar selectablely engageable coupler, and the rotor flux path elements are arranged on said common shaft such that the major axes of the flux path elements are equally spaced on the shaft and wherein the stator poles are in the same position with respect to the common shaft for each motor segment. In another embodiment of this arrangement, the motor has two motor segments and two rotor flux path elements and the rotor flux path elements are arranged on the common shaft such that their major axes are spaced 90 degrees apart.
In a further embodiment, the motor has rotor counterweights to statically and dynamically balance the mass of the rotor flux elements.
In a further embodiment, the motor has starter windings adapted to start the motor in a desired rotational direction.
In a further embodiment, current generated in the windings from collapsing magnetic fields is captured and used.
One advantage of the presently disclosed system and method is that it addresses the drawbacks of existing systems.
Another advantage of the presently disclosed system is to provide a direct current motor which develops a significantly reduced Speed Voltage (Vs) component of the Back EMF.
Another advantage of the presently disclosed system is to provide a direct current motor which makes use of a plurality of salient poles within its stator structure that may possess characteristics different than typically employed by existing Speed Voltage dependent systems. For example, the stator poles should be arranged or constructed to be protected from flux movement in two directions in order to minimize eddy currents, and related iron losses. For example, fabricating all or part of the pole pieces from different metals, using grain orientation, using ferrite materials, using distributed air gap materials, or laminations disposed at right angles with respect to one another, are some techniques that may be implemented to inhibit the production of eddy currents, and thereby lessen iron losses.
Another advantage of the presently disclosed system is to provide a direct current motor which employs a uniquely shaped rotor having a constant air gap with respect to the salient pole pieces. The constant air gap contributes to a smaller rate of change of inductance in the magnetic circuit, thereby reducing the speed voltage component Vs.
Another advantage of the presently disclosed system is to provide a direct current motor which employs a shaped rotor having no coils, windings, conductors or bars within its structure. This also contributes to a lower speed voltage component Vs of the Back EMF.
Another advantage of the presently disclosed system is to provide a direct current motor whose operation is governed by controller, such as an electronic controller, on designed as to orchestrate, synchronize, and control all the internal functions of the direct current motor.
Another advantage of the presently disclosed system is to provide a direct current motor with a surplus of salient pole windings which are configured to store re-usable magnetic energy within the stator power coil windings. The surplus windings arise from the additional windings possible with the presently-disclosed designs compared to the amount of windings on a similar capacity, traditionally designed motor.
These and other advantages are achieved in the presently disclosed system by providing a unique arrangement of stator and rotor geometries in conjunction with an electronic controller such that rotation is achieved by means of reluctance switching, synchronized by a position sensor, and acting in response to an electronic controller such that motor input power is properly managed and directed so as to produce a continuous rotation, while simultaneously recovering unused energy momentarily stored within the stator windings.
One embodiment of the presently disclosed system employs a rotor fabricated from a stack of steel disks, chemically insulated from one another to discourage and reduce eddy currents, The disks may be pressed upon an arbor which, in turn, is obliquely disposed with respect to the intended axis of rotation, and suitably machined on as to produce an assembly with a peripheral contour generally equivalent to that of a cylinder. The stator may be composed of a plurality of salient pole sets, each set comprising a pair of poles, and associated windings, arranged 180 degrees apart from one another upon the stator, and each pole set angularly displaced from one another by a desired number of mechanical degrees.
In some embodiments, each pole set may also be provided with a concave pole face, whose radius is slightly greater than the radius of the rotor. The rotor, therefore, defines air gap of continuous dimension when rotated. The rotor is in magnetic series with each set of magnetic poles, thereby completing the magnetic circuit, and the rotor reacts to each set of energized poles by undergoing a mechanical displacement equal in degrees to the pole set's mechanical distribution around the periphery of the stator assembly. As the rotor rotates, the zone in which the flux is coupled to the active pole pieces may vary in position along the length of each pole face. However, the width of the air gap separating the pole face from said rotor will not vary.
This arrangement permits the magnetic potential within the air gap to remain substantially constant, thereby minimizing the change in induction which would normally give rise to the development of a large Speed Voltage (Vs). A greatly reduced Speed Voltage allows a reduced Back EMF in this embodiment of the disclosed direct current motor.
Other aspects and advantages of the presently disclosed systems and methods will now be discussed with reference to the drawings.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that various changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.
Rotor assemblies (3, 4) each consist of a stack of silicon steel laminations (9), a molded ferrite core, or any other high permeability magnetic material designed to suppress eddy currents, and machined so as to produce a section of a right circular cylinder canted at an angle of 45 degrees with respect to the motor shaft (10). When viewed face on, the rotor structure appears to be elliptical in shape. However, the side view depicts a rhomboid tilted at 45 degrees. This angle may not be the most optimal angle, and it should be realized that other angles may be employed without departure from the spirit of the invention.
The common shaft (10) may also carry counter weights (7, 8), as depicted, which function to ensure a smooth rotary motion by suppressing mechanical vibrations produced by the uneven mass distribution of the elliptical armature sections (3,4). In another embodiment, each motor segment may include a clutch (25), or some other selectablely engageable coupler in order to couple independent shafts into a common shaft (10). Of course, as many motor segments from one on upwards can be coupled in this, or a similar, manner.
Each stator assembly contains an individual stack of stator laminations (16, 17) or a magnetic ferrite cylinder, from which extend two or more salient pole projections (12, 13), each of which is wound with a power coil (18). The face of each pole projection (5, 6) is extended to the right and the left of center to ensure continuous air gaps of constant dimension (19, 20), which are aligned parallel to the rotor's edge contour regardless of its angular disposition. Those familiar with the art will realize that it may be possible to install more than two pole projections per armature without departing from the spirit of this invention. Under these conditions, the motor will, of course, operate with a single rotor.
The pole projections in each stator section are parallel to each other, but the rotor sections are displaced upon the shaft by a predetermined mechanical angle: 90 degrees for two pole sets 120 degrees for three pole sets, etc.
The motor shaft extends several inches beyond the end bell housings (14, 15) on each side of the motor. One end of the shaft is utilized as a take off point for mechanical power, or load, while the other side of shaft carries a shaft position indicator (21), which is an angular transducer, and may consist of a simple rotary encoder, or a more complex device containing discrete optical sensors and slotted disks.
The stator power windings may be connected in series or in parallel as preferred. The windings receive their drive pulses from switching transistors, MOSFETs, or other solid state switching devices within the controller (22), which in turn receive their firing instructions directly, or indirectly, from the shaft position sensor (21).
Power resistor (23) is used as a sump to harmlessly dissipate any remaining energy associated with the collapsing magnetic fields within the stator as the motor rotates.
Drawing attention now, to
Magnetically, this elliptical rotor has some very interesting properties.
Accordingly, the elastic nature of the lines of flux will tend to exert a torque upon the rotor geometry, forcing the assembly to rotate 90 degrees, whereby the shortest path is available for the magnetic lines to complete their circuit as is evident in
This process does not require the presence of a “secondary” magnetic coil, the addition of which would tend to decrease a motor's overall inductance, by means of quadrature coupling, or armature reaction, during normal operation.
One embodiment of this invention employs two rotors, each fabricated from a stack of laminated disks, pressed upon arbors which are obliquely disposed with respect to the intended axis of rotation, and then integrally machined in order to provide both rotors with peripheral contours equivalent to that of a cylinder while retaining their overall elliptical shape. Each stator section is formed by a lamination stack having two, spaced-apart, salient pole projections terminating in concave pole faces whose radii are slightly larger than the radius of each rotor. Both rotors thereby define air gaps of constant dimension while rotating. Each rotor is in magnetic series with two air gaps and two pole pieces and a complete magnetic circuit which contains its own coils for the production of magnetic flux. Each magnetic rotor circuit is separate and distinct from each other magnetic rotor circuit, although they share a common output shaft. An angular position sensor or shaft encoder is positioned at one end of the output shaft, and sends electronic position signals to a DC power supply/controller, which in turn sends pulses to the motor stator sections as required.
The application of a current pulse to a given set of stator coils causes the rapid rise of magnetic flux within the selected stator section and its associated rotor. The increased flux density then causes the rotation of the active rotor, as the flux lines “shrink” to ensure their manifestation in a circuit of minimum length. The output torque is produced by the laws of magnetic reluctance acting in conjunction with the innovative geometry of the rotor. No current carrying conductors are involved in the rotor.
As the first rotor reaches its position of minimum cross-sectional diameter, the shaft encoder then directs the electronic controller to send a power pulse to the second rotor, and the operation repeats itself. When this procedure is enacted every 90 degrees, the result is a smooth angular rotation, and the production of a continuous average torque. However, a secondary result of this arrangement is the production of an electrical output from each stator section as a result of the collapsing of its magnetic field at the end of each power cycle. This electrical energy may be harmlessly dissipated in a sump resistor, or it may be put to use, for example in powering other devices, including lamps or heaters or recovered to supply a portion of the energy used to drive the motor.
In an embodiment, an exemplary motor utilizes a rotor geometry consisting of a lamination stack or a molded ferrite shape, canted at a specific angle with respect to the output shaft, while retaining a circular cross section to the axis of rotation, and presenting an overall elliptical appearance in its own plane. This arrangement allows for a constant air gap to be maintained between the rotor's edge and the pole pieces thereby producing mechanical torque without the utilization of coils or conductors residing anywhere upon said rotor.
One embodiment of the motor employs a plurality of “elliptical” rotors mounted upon the same output shaft, but positioned such that each rotor section is advanced a certain number of mechanical degrees from the others such that torque production over 360 degrees of rotation is shared equally by the number of rotors utilized. The motor also has a plurality of pole sets and separate magnetic circuits, such that each elliptical rotor section is associated with its own external source of magnetic flux, regardless of the fact that they share a common output shaft. Accordingly, the salient stator pole projections will all reside in the same plane and be parallel to each other, while the rotor sections will be displaced upon the output shaft by predetermined mechanical angles; 90 degrees for two pole sets, 120 degrees for three pole sets, etc. Those skilled in the art will realize that this arrangement may be reversed without departing from the spirit of the invention. Likewise, those skilled in the art will also realize that it is possible to construct a single, standalone, motor utilizing a single rotor and stator section.
Referring now to
Sensing this arrangement, the shaft position sensor (21) will cause the controller (22) to energize starting windings (not shown) which will rotate the motor shaft in the desired direction, while simultaneously sending a current pulse into the left hand pole set depicted in
The appearance of lines of force within the first rotor segment will cause a twisting action upon that rotor's lamination stack, such that torque is produced upon the motor output shaft in the desired direction. At the same time, the right hand rotor is rotated, by the turning shaft, into a position of readiness with respect to the right hand magnetic pole set.
The shaft position sensor (21), illustrated in
The average torque available on the motor output shaft will be a function of the cooperative effort developed by both rotors over each mechanical revolution. The output torque developed by this method is strictly a reluctance torque, generated as the lines of magnetic flux within each rotor section alternately shrink in an attempt to provide themselves with the shortest possible magnetic path between poles.
It is important to realize that this torque-producing mechanism does not involve any interaction of either stator's magnetic field with a current carrying conductor of any kind, neither in the form of a Speed Voltage interaction, nor in the form of a transformer coupling with a time-varying field. Instead, the torque appearing on the motor shaft is a direct function of the rotor's geometry interacting with forces produced at the boundaries between the rotor body and the stator poles, and by internal cam action particular to the rotor geometry in the presence of a contracting flux.
Magnetic energy stored in the stretched lines of flux between each pole set must be dissipated as each field structure collapses in response to instructions from the controller. This will ensure that an “empty” inductor wilt be available at the start of each 90 degree cycle. Accordingly, fly-back diodes are provided in association with each power winding. The diodes direct pulses generated by the collapsing fields into a sump or load resistor (23), where they may be harmlessly dissipated as excess heat. Alternatively, said energy may be used to power other electrical appliances external to the motor, or may be applied to a capacitive storage element and then utilized to send power back to the main power supply.
Because of the rotor geometry, in conjunction with the fact that this type of reluctance motor carries no rotor windings, at least 50% of the I squared R losses, stray copper losses and hysteresis losses experienced by traditional motor technology will be avoided in accordance with the spirit of invention.
Energy savings of this magnitude are possible primarily because of the constant air gap afforded by the rotor's geometry. However, it should be remembered, that any electromagnetic device so designed as to prevent a large change in the reluctance of its magnetic circuit, while ensuring a constant air gap during the course of any mechanically sponsored alteration in the mean circuit length, shall experience only minute variations in inductance. The operational benefits of such an arrangement will be that any force produced or work done by the electro-mechanical process, will have a minimal effect upon the magnetic excitation current.
Additionally, the use of high frequency switching technology to develop the required pulses of drive current will ensure that conversion efficiency, or the transformation from electrical power to mechanical power, will be attainable in the high 90 percentile range.
Application of concepts herein disclosed may be arranged such that the rotor segments may be joined either in series, as depicted in
The scaling of these embodiments is relatively straightforward. Accordingly, no unusual difficulties are anticipated in producing small, medium or very large sized motors of this design.
in another embodiment, an electric motor cluster comprises several stator sections each possessing a minimum of two salient pole projections, wound with power windings, and each having a single armature rotor. Each individual rotor is angularly displaced one from the other, while mounted upon a common frame, and geared together such that each motor section contributes to the rotation of a common output shaft. Those skilled in the art will also recognize that it is possible to deploy a single, standalone motor with a single rotor and stator pair rather than as part of a cluster.
Such an arrangement not only allows for the combining of motor output powers and the removal of flutter from the final mechanical output, but simultaneously allows for a large increase in output torque by virtue of the necessary reduction gearing. The embodiment suggested within this particular disclosure lends itself perfectly to applications within the field of electric vehicle propulsion, particularly in those cases where the prime mover is to be located within the wheels of the vehicle. However, other applications are easily envisioned.
Each motor section shall consist of stator and armature elements as described in PCT application number PCT/US09/46246, filed on Jun. 4, 2009, and entitled “PULSED MULTI-ROTOR CONSTANT AIR GAP RELUCTANCE MOTOR.” The motor may consist of the following features:
A stator, consisting of a stack of laminations, or a molded ferrite core, so constructed as to provide at least one set of salient magnetic poles, spaced apart 180 mechanical degrees, and situated so as to allow an air gap to exist between the stator structure and the armature of the motor. Each salient magnetic pole projection may be wound with power windings, the function of which is to produce a magnetic field of considerable strength, and direct the same through the air gaps and into the body of the motor's armature.
An armature, also consisting of a stack of laminations, or a molded ferrite shape, so designed as to present each set of field poles with a cylindrical contour, perceived beyond each air gap, while retaining an elliptical profile with respect to the output shaft. The armature sections carry no electrical windings of any kind, and require no slip rings or, field coils or permanent magnets. However, armature segments may require shaft-mounted counter weights to offset their eccentricity, and maintain angular balance during rotation.
The power windings wound upon the salient pole projections, are energized by pulses of electric current produced by a DC power supply and provided through an electronic controller unit, or through a mechanical commutator, etc. The pulses are automatically applied to the salient pole nearest the longest flux path available through a particular rotor section, as determined by a shaft position sensor, or the geometry of a commutator.
The appearance of flux lines linking any stator pole set and any armature section immediately causes a rotation of the motor's output shaft by 90 mechanical degrees as the flux lines seek to establish the shortest possible path available for the completion of their magnetic circuit within a given motor.
This action is transmitted to the main output shaft via a large reduction gear, thereby increasing the available torque. In the motor cluster embodiment disclosed herein, several motor sections are positioned such that each may contribute to a common mechanical output. However, several such motor sections may be energized simultaneously, thereby increasing the output power in multiples.
Upon detecting motion, the shaft position sensor communicates the change in position of the output shaft to the electronic controller, and current flow is then terminated in each active stator section, and instantly initiated in the stator section windings next scheduled to be activated. By means of such switching action, which occurs at even intervals of mechanical degrees, a constant rotary motion is ensured.
The rotor assembly 3 within each motor section, consists of a stack of silicon steel laminations 9, or a molded ferrite of appropriate shape, or any other high permeability magnetic material designed to suppress eddy currents, machined so as to produce a section of a right circular cylinder canted at an angle of 45 degrees with respect to the motor output shaft 10. When viewed face on, the rotor structure appears to be circular in shape. However, the side view depicts an ellipse tilted at 45 degrees. This angle may not be the most optimal angle, and it should be realized that other angles may be employed without departing from the spirit of the invention.
Each motor shaft 10 may also carry counter weights 7, as depicted, which function to ensure a smooth rotary motion by suppressing mechanical vibrations produced by the mass distribution of the eccentric armature design 3. Each motor shaft carries a high speed output pinion 24 which is designed to mesh with the main output gear as shown in
Each stator assembly contains an individual stack of stator laminations 16 or a magnetic ferrite cylinder, from which extend two or more salient pole projections 12, each of which is wound with a power coil 18. The face of each pole projection 5 is extended to the right and the left of center to ensure continuous air gaps 19 of constant dimension. The pole faces are aligned parallel to the rotor's edge contour regardless of its angular disposition. Those familiar with the art will realize that it may be possible to install more than two pole projections in association with each armature without departing from the spirit of this invention.
Referring now to
This arrangement allows for four motors to be energized at any one time, with power overlaps and torque-sharing occurring at 45 degree intervals. This feature serves to smooth out the total torque delivered to the output shaft, allowing for a more continuous delivery of power, as each contributing motor develops its output torque out of phase with respect to each of the others. Total motor action during operation may be appreciated by studying the coil energizing truth table depicted in
Referring now, to FIG, 12, it will be noted that switches S1A through S8A, and switches S1B through S8B, are used to control the power winding coil sets in each motor section. The coil sets are labeled A, A′ and B, B′ for each motor as shown in
Returning now to
Observing
It should be understood that the embodiment discussed in this application and depicted in associated
As discussed previously, the parasitic effect of Back EMF, and motors designed to exploit Speed Voltage (Vs), imparts several drawbacks to existing systems. At least in part to avoid these and other drawbacks, the presently disclosed systems and methods are designed to operate on the production of Transformer Voltage (Vt). As disclosed herein, at least one advantage of such a design is that it allows the energy associated with the magnetic field to be re-captured and, in great measure, re-utilized.
To exploit the Transformer Voltage (Vt) instead of the Speed Voltage (Vs), the presently disclosed systems and methods implement the Wowing two design principles arising out of the above discussion, and an understanding of the importance of equation 6 above. The first design principle implemented to exploit Transformer Voltage (Vt) is to introduce a parameter dl/dt corresponding to the change in magnetic circuit length over time. The second design principle is that to minimize the Speed Voltage (Vs) component the relation provided in equation 8 must be zero, or nearly zero. One way to accomplish a nearly zero Speed Voltage (Vs) is to minimize dL/dt by designing the air gap to be constant. These two design principles are described in greater detail below.
The consideration of the change in magnetic circuit length over time (dl/dt) can be described with reference to
FIG. 14B magnetic circuit length=g2+l2+g2=2g1+l2.
Therefore, by design, when the shaft 510 rotates, the magnetic circuit length will vary in time between a maximum proportional to e and a minimum proportional to l2. Furthermore, as the dimension of the air gap does not change (i.e., g1=g2), the contribution of dL/dt is zero, and the Speed Voltage component is, by design, zero as well.
The following is a closer examination of the effect of the new parameter, dl/dt, or a change in magnetic circuit length with respect to a change in time in accordance with the disclosed inventions. Beginning from the classical formula for inductance (equation 13):
L=(N2μA)/(Kl),
where N is the number of turns, μ the permeability, A the cross-sectional area, l the magnetic circuit length, and a K constant of proportionality. In most inductance calculations, all of the above parameters are usually considered to be constants. However, as explained above, in the presently disclosed embodiments the length of a magnetic circuit changes in time. Accordingly, it is interesting to examine the magnitude of the resulting change in inductance using the following values determined experimentally by the above-named inventor.
In one embodiment, measuring a mean magnetic path around the stator equivalent to the mean circumference Cm, gives 43.982 inches in length. A major axis for a rotor stack 520 of 14 inches long gives the total circuit length l1=57.982 inches. As discussed in connection with
L1=0.103480 Henrys, and L2=0.104346 Henrys.
The difference of these two values ΔL is calculated to be 8.666×10−4 H, and when this change occurs in one quarter of a rotation at 60 HZ, a measured Back EMF of 2.5 Volts results. This is a remarkable result, considering the fact that a change of the same degree within the air gap of a conventional Speed Voltage based motor generates hundreds of volts.
To illustrate the significance of the above result, we compare
In correlation with the
E
T
=IdΦ+ΦdI.
For the values shown on
Unlike the air gap calculation corresponding to
The contrasting, and unexpected result of the present invention is shown in
As demonstrated above, the difference in behavior here is very distinct from conventional systems: a small decrease in current (I), and an equally small increase in flux (Φ). This can only be possible without the presence of a speed related Back EMF. Accordingly, it stands to reason that the energy usually associated with the Speed Voltage (Vs) has been reduced to a value that cannot possibly support the measured shaft horsepower. However, because the primary relationship for energy in this system is:
IΦ=Ef+Ec,
it also stands to reason that if the co-Energy factor is reduced, and Field Energy remains constant, then there must have been a change in the supply energy. This can be understood by looking at the power involved, rather than from the energy domain. Recalling that the total applied voltage is the sum of the voltage drops around the equivalent motor circuit, we can write:
dΦ/dt=LdI/dt+I dL/dt,
where dΦ/dt is the source voltage, LdI/dt is the Transformer Voltage (Vt), and I dL/dt is the Speed Voltage (Vs). Substituting V for dΦ/dt, we obtain:
V=LdI/dt+IdL/dt.
However, the actual source voltage is the sum of Vt, Vs and Vr, so we must modify the above expression accordingly, thus obtaining:
(Vt+Vs+Vr)=(LdI/dt)+(IdL/dt)+Vr.
Because Watts are the product of Volts and Amps, the above expression is now multiplied by I to get:
(Vt+Vs+Vr)I=I(LdI/dt)+I(IdL/dt)+IVr.
From Ohm's law we know that Vr is actually equal to Ir, thus we may substitute:
(Vt+Vs+Vr)I=I(LdI/dt)+I(IdL/dt)+I2r.
Thus, we finally arrive at an expression in Watts which represents the motor in question.
Recalling the fundamental nature of equations it is obvious that whatever we change on one side of the equal sign, we must change on the other side to maintain a mathematical balance. Accordingly, Vr I must equal I2r as the motor losses are constant. If the Speed Voltage parameter I(IdL/dt) is reduced almost to zero, because of rotor geometry and a constant air gap, then it stands to reason that its supporting component (Vs) in the source voltage must also be reduced by the same proportion. This must be so if power, and its associated energy, are to be conserved. Accordingly, it now becomes apparent that the Back EMF is a parasitic agent, the presence of which demands a higher source voltage to perform the same work; Back EMF is a system loss. However, this kind of loss only destroys potential, it does not evolve heat, therefore, it has gone unnoticed until now.
Another unexpected consequence of the presently disclosed technology resides in the fact that the reluctance torque is not affected. The torque generating mechanism does not care if it is supported by the field energy or the co-energy, it simply responds to the presence of flux according to the formula:
T=−½Φ2dR/dθ.
As noted above with reference to
The differences between Speed Voltage (Vs) dependent systems and Transformer Voltage (Vt) dependent systems are many and pronounced. The most pronounced difference between Vt and Vs lies in the inductive mechanism with which each potential is associated. Regarding the term IdL/dt, under dimensional analysis yields that dL/dt has the dimension Joule-seconds/coul2, which is representative of a resistance. Hence, I2 (dL/dt) is dissipative by its very nature, while the expression VI, from which LdI/dt is derived, can easily describe a reactive condition. Energy can be extracted from a reactive situation, but not from a dissipative relationship.
The recaptured electrical output 810 power is the same power that was applied earlier (e.g., 802), minus all the associated losses. In operation, the input power 802 pulse, and the recapture power 810 pulse cannot exist at the same time. They are 180 electrical degrees out of phase with each other.
The output power 908 available at the motor 904 shaft, may be approximately 3.5 HP, and the overall motor efficiency may be 79.84%, as measured by contrasting total electrical input from controller 900 to the average mechanical output 908 at the shaft.
Almost simultaneously, each collapsing motor field produces an electrical output 909 of 586.416 watts, which represents the re-captured field energy. These pulses 909 are then delivered to the recovery section 910 of an electronic controller, and then may be stored, for example, in the re-capture capacitor bank 912. In some embodiments, energy from this capacitor bank 912 could be removed if necessary, and used to supply power to external appliances (shown in phantom at 914, 916.
As power pulses are delivered to the recapture capacitor bank 912, voltage across these capacitors will begin to rise. Once the potential reaches a certain pre-determined value, the feedback controller 918 may automatically start sending power back to the main capacitor bank 920. In some embodiments, the power delivered by this motor 904 operation may be monitored by the feedback watt meter 922.
A power accounting at this point demonstrates the subtle energy workings at play within this motor system:
(3,264.424 watts)−(Motor Losses=658.128 watts)=(shaft power of 2,606,296 watts);
(Recaptured power is 0.9×2,606.296)=(2,345.666 watts, sent to feed-back).
However, (3,264.424 watts)−(2,345.666 watts)=(918.758 watts), which represents a power shortage. Therefore, this amount must be drawn from an external power source, such as the utility line or source voltage 924. Because of the unique features of the disclosed embodiments, the system of
While this apparent system efficiency is remarkable, it is understandable in view of the above explanation of Transformer Voltage (Vt) operation (and resultant lack of Back EMF). Furthermore, the system inputs and losses are as expected:
Thus, the line only supports the system losses, while the shaft power is supported by the change in field energy per unit time. As expected, the motor will not operate without line power.
As noted herein, the unique characteristics demonstrated by the disclosed DC motor, are the result of a special cooperation between the rotor design and the stator design. With respect to the stator, several design features are important. Therefore, the DC motor as disclosed herein may include combinations of the following features: an even number of salient stator poles, salient poles that are protected from flux movement in two directions, poles that are designed to be as short as possible, and pole windings should be of adequate wire size, but with as many turns as desirable.
Some reasons and advantages of the above-noted stator design features are the following. The even number of salient poles is advantageous in establishing the flux field to impart a force on the rotor, because each pole set constitutes a complete magnetic circuit for each phase with two poles being the minimum set.
As explained herein, and with reference to
Also illustrated for this embodiment in
Additional embodiments of stator poles may also be implemented to minimize eddy currents. For example, another embodiment is to have the pole face, or shoe 1028, made of a material such as sintered steel, ferrite, or distributed air-gap material, and then bond, or otherwise fasten, the shoe 1028 to the bottom portion 1030 of the stator pole. Likewise, other embodiments may also implement stator pole pieces comprising grain-oriented steel, with the grain best oriented for lateral flux movement. Embodiments employing combinations of these techniques for eddy current minimization are also possible.
Likewise, for some embodiments, the salient poles are designed to be as short as is optimal in order to optimize the overall magnetic circuit length. This has the advantage of also lessening motor iron losses.
Finally, for some embodiments, the design of the pole windings (e.g., windings 1026) is to be of adequate wire size, but with a number of turns that is optimal. This has the advantage of keeping I2R (i.e., copper) losses to a minimum. The wire size and number of turns are preferably optimized so that enough turns are used to establish a magnetic flux of sufficient magnitude, while also keeping the I2R losses to an optimal minimum. Typically, relative to a comparable Speed Voltage dependent motor, the presently disclosed stator designs will accommodate a greater number of windings per pole.
As noted previously, the rotor design features of the presently disclosed invention also contribute to the herein described performance. As discussed above, an important feature of the disclosed rotor is that it be shaped to assist in the reduction of the factors that contribute to the generation of Back EMF. To that end, rotors that exploit Transformer Voltage (Vt) in accordance with the present disclosure will be designed to form a constant, or substantially constant, air gap with respect to the stator poles.
In addition, a rotor designed to exploit Transformer Voltage (Vt) in accordance with the disclosed embodiments of the invention will also facilitate the creation of a variable length magnetic circuit path. In general, one way to design a rotor capable of creating a variable length magnetic circuit path is to create an ellipse that, when rotated, has a circular cross-section. For some embodiments, such an ellipse may be created in the manner illustrated in
Having described the relevant design features for the stator and the rotor, we turn now to a description of some embodiments of the instant DC motor system. Traditionally, a DC motor consists of three main components; a stator assembly for supporting the magnetic field coils, a shaft-mounted armature, or rotor, for supporting windings of its own, and a commutator, also shaft-mounted, which supplies a timed switching function by means of two or more carbon brushes for controlling the supply electrical current to the rotating armature assembly from an external power supply.
For example, in some embodiments of the direct current motor any suitable type of bearing 1101 may be implemented depending on the design circumstances, intended implementation, environment of application, or the like. Thus, bearings 1101 may be single roller bearings, multiple-roller bearings, thrust bearings, conical bearings, metallic sleeve bearings, or other suitable type of bearing.
For embodiments where magnetically conductive rotor stack 1104 is mounted in a canted position with respect to shaft 1100, it may be desirable to include rotational stabilizers 1102 to dynamically balance the rotation of the shaft 1100. Any suitable stabilizers 1102 may be implemented. For example, in some embodiments stabilizers 1102 may take the form of machined metallic rings containing distributed tungsten weights to achieve dynamic balance, Other configurations are also possible.
Likewise, in sonic embodiments, the arbor 1103 may comprise any suitable arbor or mounting mechanism for securing the conductive stack 1104 to the shaft 1100. For example, in sonic embodiments, where conductive stack 1104 comprises a laminate stack, it may be desirable to use a compression arbor 1103 that facilitates the securing and positioning of the laminate. Furthermore, arbor 1103 may be formed from any alloy, compound or element which may serve to enhance motor performance, Of course, other arbors 1103 may be implemented depending upon factors such as the type of shaft 1100, design of the conductive stack 1104, as well as other factors.
In some embodiments, magnetically conductive stack 1104 may comprise a stack 1104 of individual disks laminated together. In other embodiments, stack 1104 may comprise a unitary structure, or other similar solid magnetically conductive path. In still other embodiments, stack 1104 may be replaced with any suitable magnetic material that enhances motor performance, including, but not limited to, various steel alloys, various paramagnetic materials, and distributed air-gap materials such as sintered steels and the like.
Further, in some embodiments the stack 1104 is fashioned to present a substantially cylindrical profile, such as one described with reference to
Likewise, a variety of shaft position sensors 1108 may also be implemented depending upon factors such as motor design, intended implementation, and environmental circumstances. For example, the shaft position sensor 1108 may be comprised of any mechanism capable of generating and sending data to an electronic controller, including, but not limited to multi-quadrant disk encoders with appropriate sensors, slotted disks with optical sensors, magnetic studs with Hall-Effect transducers, metal studs with magnetic proximity sensors, and any other arrangement that may supply necessary information to the controller, either digitally or in analogue fashion. Likewise, some embodiments may locate components of the shaft position sensors 1108 in a variety of locations. For, example, an indicator, sensor, transducer, or other portion of the sensor 1108 may be positioned on the shaft (e.g., shaft 1100), and may be in communication with other portions of the sensor 1108 located elsewhere. Other position or orientation sensors 1108 are also possible.
By way of non-limiting example, a conventionally designed, variable air gap DC motor of a source voltage V and current I may include a number of windings N to produce an output power P for the given V and I. By implementing the Back EMF reducing design disclosed herein, a constant air-gap DC motor can exploit a surplus of windings Ns>N for the same V and I and deliver the same, or greater P. Alternatively, using the concepts disclosed herein, lower values of V and I can be implemented with the Back EMF reducing designs disclosed herein to deliver the same magnitude of P.
As discussed in connection with
For some embodiments implementing a multi-pole stator assembly, the stator assembly 1200 may comprise silicone steel laminations, sintered steel alloys, distributed air gap material, or any other material which may suppress the formation of eddy currents and enhance motor efficiency and performance. Further, for some embodiments the stator assembly may have at least four (4), diametrically opposed salient pole projections 1202, situated at even angular increments around the stator periphery, and aligned in pole pairs 180 mechanical degrees apart, so as to constitute a complete magnetic path through the rotor at all times. Other configurations are also possible. For example, the embodiment shown in
As discussed, in some embodiments, each salient pole projection 1202 supports an electrical winding or coil 1203 that develops a magnetic field in response to the passage of a DC Current through the winding 1203. Surplus windings 1206 may likewise be integral with windings 1203 and, likewise, be energized and contribute to the magnetic field. This field provides a magnetic force which acts upon the rotor assembly 1190 and produces a useful torque.
In some embodiments, the windings 1203 and 1206 supported by said stator salient pole projections 1202, are inter-connected so as to produce an additive magnetic effect across the entire pole pair, regardless of the magnetic polarity provided by the electronic controller. Other configurations are also possible.
As shown on
As shown in
As shown in
As shown in
The following is a description of methods of operation for some exemplary embodiments of the presently disclosed system.
Referring now to
In some embodiments, the controller 1503 may then initiate a timing function, which will allow the rotor stack 1104 to turn through a critical mechanical angle, (e.g., less than 90 mechanical degrees) at which point controller 1503 may cause a DC current to be applied to pole-coils 1202B and 1202E, thus locking the rotor at 30 degrees for an instant in time. Simultaneously, the controller 1503 may switch off the current in pole-coils 1202A and 1202D, allowing the original magnetic field to collapse down through windings 1203A and 1203D, producing a high voltage pulse, and an accompanying current, which the controller 1503 may then direct to recapture bank 1508.
The relatively slow collapse of the field lines through pole-coils 1202A and 1202D, allows a smooth hand-off of the rotor stack 1104 to the newly energized pole-coils 1202B and 1202E, thus completing a total angular displacement of 60 mechanical degrees.
The charge and discharge rates of the magnetic fields in and through the windings involved shall be a function of factors such as, the particular embodiment's Supply Voltage developed within Power Supply 1501, the inductance-resistance time constant L/R, the value of the voltage contained within the Recapture Capacitor Bank 1508, and the impedance of the external load (e.g., 1510 or 1511.),
This same switching procedure may be repeated for pole-coils 1202C and 1202F, and then again for 1202A and 1202D, thereby completing half a rotation, and positioning the rotor stack 1104 properly for the next 180 degree rotation. In some embodiments, the controller 1503 may always supply current of proper polarity so as to prevent reinforcement of magnetic domains within the stator 1200.
The next rotation through 180 degrees may be traversed in the same way, re-energizing pole-coils sets 1202B&E, 1202C&F, and finally 1202A&D thereby completing one complete revolution. Each time the controller 1503 switches off a coil set, the resulting collapse of the associated magnetic field will develop an electric pulse which is automatically delivered to the Recapture Capacitor Bank 1508.
During normal high speed operation, a continuous stream of electrical pulses will be directed into the Recapture Capacitor Bank 1508, as shaft 1100 power is being delivered to the mechanical load 1507. The continuous stream of pulses would ordinarily cause the voltage across the Recapture Bank 1508 to rise to destructive levels if the energy contained therein was not utilized in a constructive fashion. Accordingly, this recaptured energy can be drawn off by application of a DC Load 1511 or an inverter and AC Load combination (e.g., 1509 and 1510), respectively. The utilization of Recaptured Inductive Energy in a load external to the motor 504 shall be referred to as the Open Power Configuration.
Referring now to
This circuit arrangement allows the DC Motor 1504 to become the load for the Recapture Capacitor Bank 1508, thereby reusing a significant percentage of the Recaptured Energy, and reducing the power required from the Main DC Power Supply 1501. Theoretically, this Feedback action may be perfected to the point where the external power need support only the system losses. When this is accomplished, the power drawn by the motor will remain constant, while the external power requirements will diminish in proportion to the power contributed by the Recapture Capacitor Bank 1508.
The electronic functions described in accordance with the operation of this Direct Current Motor 1504, are all directed and synchronized by the controller 1503. The operational logic of this device is demonstrated in
System Components 1700 through 1711, designated in
Referring now to
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
This application is a continuation-in-part of application Ser. No. 12/993,941, which has a 35 U.S.C. §371(c) date of Dec. 3, 2010, and which in turn is a 35 U.S.C. §371 filing of Application No. PCT/US09/46246, filed Jun. 4, 2009, which in turn claims the benefit under 35 U.S.C. §119 to provisional Application No. 61/085,824, filed Jun. 4, 2008, and the entire contents of each are hereby incorporated by reference. This application is also a continuation-in-part of application Ser. No. 13/390,437, which has a 35 U.S.C. §371(c) date of Feb. 14, 2012, and which in turn is a 35 U.S.C. §371 filing of Application No. PCT/US10/45298, filed Aug. 12, 2010, which in turn claims the benefit under 35 U.S.C. §119 to provisional Application No. 61/234,011, filed Aug. 14, 2009. This application is also related to the following concurrently-filed Applications: application Ser. No. ______, titled “Controller for Back EMF Reducing Motor;” application Ser. No. ______, titled “Three Phase Synchronous Reluctance Motor With Constant Air Gap And Recovery Of Inductive Field Energy;” and Provisional Application No. ______, titled “Multi-pole Electrodynamic Machine With A Constant Air Gap And An Elliptical Swash-Plate Rotor To Reduce Back Torgye;” each of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61058824 | Jun 2008 | US | |
| 61234011 | Aug 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12993941 | Dec 2010 | US |
| Child | 13562233 | US | |
| Parent | 13390437 | Feb 2012 | US |
| Child | 12993941 | US |
