A “generator” is an electromechanical device that converts motive power (i.e., mechanical energy) into electrical power (i.e., electrical energy). Generators accomplish this conversion by applying the principles of Faraday's law of induction. More specifically, generators generate an electric current, by either:
In most traditional generators, the second of these two approaches is used, i.e., a rotating magnetic field is applied to a stationary conductive coil.
In an Alternative current (“AC”) generator, the electric current is commonly drawn from the conductive coil using slip rings—resulting in a sinusoidal electrical output. Such traditional AC generators have two primary components, namely: (a) a rotor having at least one rotor coil; and (b) an armature (sometimes called stator) having at least one armature coil. The rotor produces a rotating magnetic flux while the armature remains stationary. This rotating magnetic flux induces AC electricity in the armature coils.
The rotor of an AC generator creates this rotating magnetic flux when:
As the rotor coils are rotated by the prime mover about an axis (i.e., the axis of the prime mover), the magnetic field similarly rotates at the same speed. This revolving magnetic field, in turn, intersects armature coils which are fitted around the rotor. This generates an alternating electro-magnetic field across the stator windings which, under Faraday's law, induces an electric current in the armature coils. The amplitude and direction of this current varies in a sinusoidal way over time as the rotating electric field of the rotor passes through the armature loop. In order to generate three-phase AC current, three armatures—each spaced 120 degrees apart from one another—can be used. Generally, one end of these three armature coils are star-connected and three phase AC current is drawn from the other ends.
The relationship between the AC output frequency of an induction generator (in Hz),f, the number of rotor poles, P, and the rotational speed of the rotor (in rpm), N, is governed by the synchronous speed equation, to wit:
Thus, for example, a four pole rotor generating AC output at 60 Hz:
However, such high rotational speeds can be both difficult to generate using a prime mover. Such high rotational speeds also result in relatively high centripetal forces on the rotor and the rotor coils—potentially resulting in component damage. To overcome this, additional poles can be added. For example, some modern salient pole rotors have upwards of 20 poles, thus lowering the required rotational speed of the rotor, N.
AC motors further make use of pole cores to more effectively transfer magnetic flux. The rotor coils are then wound around these pole cores at the time of manufacture. Pole cores are often made of fairly thick insulated steel lamina. By using a core made of a material with a high magnetic permeability (such as a steel core), the strength of the induced magnetic field between the rotor and the armature can be confined and guided—resulting in more concentrated magnetic fields lines. This can result in a magnetic field several hundred times stronger as compared to not have a core. Such a core helps confine and guide the rotor's magnetic field. However, the use of a solid core can cause “core losses,” i.e., power loses as a result of eddy currents induced within the core. This has the added negative effect of creating induction heating—increasing the temperature of the coil/core assembly. To overcome this, modern AC generators do not use a solid steel core; rather, they use a laminated core. Laminated cores are comprised of numerous thin sheets of steel which have been coated with insulating material to increase electrical resistance between laminations: thereby reducing eddy currents and, thus, reducing “core losses.” Laminated cores also often use electrical steel, i.e., steel impregnated with silicon to increase electrical resistivity as compared to pure iron—further reducing eddy currents and, thus, further reducing “core losses.” Similarly, a stator core is used to enhance magnetic flux transfer—with the stator core similarly constructed of insulated steel lamina.
DC power is supplied to the rotor coils via slip rings. DC power is either supplied from an external DC power source or from a small DC generator fitted on the same prime mover (in the latter case, such generators are called “self-excited generators”).
In a DC generator, the electric current is commonly drawn from the conductive coil using a commutator and brush arrangement. In this case, the electricity produced in the conductive coil gets rectified through the commutator. Alternatively, DC power can be generated by passing AC power through a rectifier.
Various attempts at improving traditional generators have made use of disk-shaped elements. One such attempt is disclosed in U.S. Pat. No. 5,606,210 (Lin) which teaches a generator having spinning magnetic disks with fixed disks made of nonmetallic material.
Another such attempt is disclosed in U.S. Pat. No. 6,040,650 (Rao) which teaches a stator having permanent magnets having metal foils with a supporting film.
Another such attempt is disclosed in European Patent Application No. EP1436883A2 (Eef Peters) which teaches a permanent magnet electrical generator/motor, a plurality of permanent magnets and stators having magnetic cores with distribution plates between the rotors and stators.
Another such attempt is disclosed in U.S. Pat. No. 6,515,391 (Whitesell) which teaches a generator with counter-rotating collectors in a radial magnetic field with stationary electrical connections.
Another such attempt is disclosed in U.S. Pat. No. 6,946,767 (Reardon) which teaches a generator having a series of rotating magnets and stationary coil elements.
Finally, another such attempt is disclosed in published U.S. patent application Ser. No. 10/911,867 (Obidniak) which teaches a generator having a series of alternative magnetic disks with stators made of nonmetallic material.
The primary object of the present invention is directed to an induction generator having alternating: (a) rotating magnetic disks; and (b) stationary induction disks (a/k/a conducting disks).
An additional object of the present invention is directed to an AC indication generator by drawing the current off of a pair of positive and negative conductor busses.
An additional object of the present invention is directed to a DC indication generator by drawing the current off of a pair of positive and negative conductor busses in series with a rectifier or other similar device.
The present invention fulfills the above and other objects by providing a generator having several major components, namely: (i) at least one magnet disk assembly; (ii) at least one conductor disk assembly; and (iii) a drive shaft (on which the magnet disk assembly is mounted). In the preferred embodiment, an outer housing encloses the magnet disk assembly(ies) and the conductor disk assembly(ies), with the conductor disk assemblies mounted to the housing by housing mounts.
As a torque is applied to the drive shaft (by a prime mover such as a steam turbine, water turbine, internal combustion engine, etc.), the drive shaft is rotated; causing each magnet disk assembly to rotate. As noted above, this is one of the two ways to create a rotating magnetic flux with respect to a conducting loop (the other way being to rotate the conducting loop). As the magnet disk assembly rotates, the corresponding magnetic field rotates with respect to each stationary conductor disk assembly (and, thus, to each stationary conducting loop (called simply a “Conductor” herein). This rotating magnetic field variously intersects the conductors such that, under Faraday's law, an electric current is induced in the conductors—creating the basis for a new type of generator.
The above and other objects, features and advantages of the present invention should become even more readily apparent to those skilled in the art upon a reading of the following detailed description in conjunction with the drawings wherein there is shown and described illustrative embodiments of the invention.
In the following detailed description, reference will be made to the attached drawings in which:
For purposes of describing the preferred embodiment, the terminology used in reference to the number components in the drawings is as follows:
As a torque is applied to the Drive Shaft 109 by a prime mover, the Drive Shaft 109 rotates; causing each Magnet Disk Assembly 101a to rotate about an axis defined by the Drive Shaft 109. As the Magnet Disk Assembly 101a rotates, the rotating Magnets 105a create a rotating magnetic field with respect to each stationary Conductor Disk Assembly 101b (and, thus, to each stationary Conductor 105b). This rotating magnetic field variously intersects the Conductors 105b. Thus, under Faraday's law, an electric current is induced in the Conductors 105b. This electric current is drawn from the Conductors 105b from the Positive Conductor Terminal 119 and the Negative Conductor Terminal 121 which, in turn, are connected to the Positive Conductor Bus 125 and the Negative Conductor Bus 127. This process is illustrated in
In the embodiment shown in
In the embodiment shown in
The example of a two-pole system is shown in
It is to be understood that while a preferred embodiment of the invention is illustrated, it is not to be limited to the specific form or arrangement of parts herein described and shown. It was be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and drawings.