Patent Publication Number: US-9893597-B2

Title: Systems, methods, and apparatus for a homopolar generator charger with integral rechargeable battery

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. application Ser. No. 14/050,783 filed Oct. 10, 2013, allowed, which is a continuation of U.S. application Ser. No. 13/435,312 filed Mar. 30, 2012, now U.S. Pat. No. 8,581,559, which is a continuation of U.S. application Ser. No. 13/271,833 filed Oct. 12, 2011, now U.S. Pat. No. 8,164,228, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to battery charging, and in particular, to a homopolar electrical generator charger with an integral rechargeable battery. 
     BACKGROUND OF THE INVENTION 
     A homopolar generator is a unique electrical generator, sometimes referred to as a Faraday disk after Michael Faraday, who developed the basic device in 1831. The homopolar generator can convert rotational energy into direct current by rotating an electrically conductive disc in a plane perpendicular to a magnetic field. Faraday&#39;s law of electromagnetic induction and/or Lorentz&#39;s force law can be utilized to explain the operation of the homopolar generator. The radial movement of the electrons in the disc in the presence of the magnetic field produces a charge separation between the center of the disc and its rim, and if the circuit is completed between the disk center and rim, an electric current will be produced when the disc is rotated. 
     Versions of the homopolar generator have been used to supply currents up to 2 million amperes, but practical use has been limited due primarily to the low voltage output and high I 2 R losses that can arise from imperfect electrical brush connections to connect external circuits. 
     Conventional battery chargers and alternators are typically designed for charging several battery cells in series, with charging currents limited by the additive internal resistance of each cell in the series. Charging cells of a battery in series tends to require extended charging periods. For example, a typical multi-cell 10 ampere-hour battery requires roughly 15 hours to reach full charge from a fully discharged condition with a 1 ampere charger. 
     Electric cars and other electric vehicles utilize battery packs having multiple rechargeable cells that are connected in series to provide adequate voltages for driving electric motors. One of the barriers for commercial success of the all electric car, however, is the long associated battery charging times. Part of the issue that can contribute to the long charging time is the internal series resistance that limits the amount of charging current that can flow through the battery. Some designers and manufactures have proposed systems to swap out the entire battery each time it is discharged to address the charging time issue. 
     BRIEF SUMMARY OF THE INVENTION 
     Some or all of the above needs may be addressed by certain embodiments of the invention. Certain embodiments of the invention may include systems, methods, and apparatus for a homopolar generator with integral rechargeable battery. 
     According to an example embodiment of the invention, an apparatus is provided. The apparatus includes an elongated shaft defining a longitudinal axis of rotation; at least one rechargeable battery comprising at least one cell having a positive and negative terminal, the at least one battery mounted substantially coaxially with respect to the shaft; one or more magnets for providing a magnetic flux field; a rotor comprising an electrically conductive portion having an inner diameter conductive connection surface and an outer diameter conductive connection surface, the rotor mounted coaxially in communication with the shaft, wherein the rotor is operable to rotate in the magnetic flux field; at least one positive output electrode operable for selective electrical communication with at least one of the battery cell positive terminal, the rotor inner diameter conductive connection surface, or the rotor outer diameter conductive connection surface, wherein the at least one positive output electrode is stationary relative to the rotating shaft; at least one negative output electrode operable for selective electrical communication with at least one of the battery cell negative terminal, the rotor outer diameter conductive connection surface, or the rotor outer diameter conductive connection surface, wherein the at least one negative output electrode is stationary relative to the rotating shaft; and a connection system comprising one or more brushes for electrically connecting one or more of the rotor conductive connection surfaces or the battery terminals with one or more of the output electrodes. According to an example embodiment, the rechargeable battery is operable to rotate with the rotor. 
     According to another example embodiment, a system is provided. The system includes a motor; an elongated shaft defining a longitudinal axis of rotation; at least one rechargeable battery comprising at least one cell having a positive and negative terminal, the at least one battery mounted substantially coaxially with respect to the shaft; one or more magnets for providing a magnetic flux field; a rotor comprising an electrically conductive portion having an inner diameter conductive connection surface and an outer diameter conductive connection surface, the rotor mounted coaxially in communication with the shaft, wherein the rotor is operable to rotate in the magnetic flux field; at least one positive output electrode operable for selective electrical communication with at least one of the battery cell positive terminal, the rotor inner diameter conductive connection surface, or the rotor outer diameter conductive connection surface, wherein the at least one positive output electrode is stationary relative to the rotating shaft; at least one negative output electrode operable for selective electrical communication with at least one of the battery cell negative terminal, the rotor outer diameter conductive connection surface, or the rotor outer diameter conductive connection surface, wherein the at least one negative output electrode is stationary relative to the rotating shaft; and a connection system comprising one or more brushes for electrically connecting one or more of the rotor conductive connection surfaces or the battery terminals with one or more of the output electrodes. 
     According to another example embodiment, a method is provided for converting rotational kinetic energy to electrical energy for charging one or more battery cells. The method includes rotating, by a shaft, a rotor in a magnetic flux field to generate current, wherein the rotor includes an electrically conductive portion having an inner diameter conductive connection surface and an outer diameter conductive connection surface, and wherein a voltage potential is induced between the inner and outer diameter connection surfaces upon rotation in the magnetic flux field; and selectively coupling the generated current from the rotating rotor to terminals of the one or more battery cells, wherein the terminals comprise a positive terminal and a negative terminal, and wherein the positive terminal and a negative terminal are electrically connected to respective inner and outer, or outer and inner diameter connection surfaces, wherein the at least one battery cell is mounted substantially coaxially with respect to the shaft. 
     Other embodiments, features, and aspects of the invention are described in detail herein and are considered a part of the claimed inventions. Other embodiments, features, and aspects can be understood with reference to the following detailed description, accompanying drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Reference will now be made to the accompanying tables and drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a diagram of an illustrative homopolar generator rotor, according to an example embodiment of the invention. 
         FIG. 2  is a side-view depiction of an illustrative homopolar generator charger with an integral battery, according to an example embodiment of the invention. 
         FIG. 3  is a side-view depiction of another illustrative homopolar generator charger with an integral battery, according to an example embodiment of the invention. 
         FIG. 4  is a diagram a rechargeable battery for use with the homopolar generator charger, according to an example embodiment of the invention. 
         FIG. 5  is a circuit diagram of a homopolar generator charger with a rechargeable battery and a stationary switching controller, according to an example embodiment of the invention. 
         FIG. 6  is a circuit diagram of a homopolar generator charger with a rotating rechargeable battery and switching controller, according to an example embodiment of the invention. 
         FIG. 7  is a flow diagram of an example method according to an example embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     Example embodiments can include a homopolar generator having one or more rechargeable battery cells. In example embodiments, electrical connections may be selectively switched to connect the cells to the homopolar rotor center and rim during rotation to charge and/or discharge the cells simultaneously. In an example embodiment, the one or more rechargeable battery cells can be selectively switched, when appropriate, to an external circuit for providing DC current output. According to example embodiments, the one or more cells can be selectively connected in parallel during charging or discharging. In one example embodiment, two or more cells can be connected in series to provide increased DC voltages for output to an external circuit. According to example embodiments, the rechargeable battery cells may rotate with the conductive rotor and a switching controller to eliminate one or more pairs of brush connections and/or to provide low resistance switchable connections from the generator rotor to the battery cells. 
     Various parts may be used and arranged for achieving efficient battery charging, according to example embodiments of the invention, and will now be described with reference to the accompanying figures. 
       FIG. 1  depicts an illustrative homopolar generator  100  with a rotor  102 , according to an example embodiment. According to an example embodiment, the rotor  102  includes at least a conductive surface. In other example embodiments, the rotor  102  may be a solid conductive disk. In accordance with example embodiments, additional rotors may be utilized in the homopolar generator charger. In example embodiments, the conductive portion of the rotor may include metals with high conductivity, preferably copper. However, other metals including silver, gold, aluminum, nickel, etc may be utilized. 
     According to an example embodiment, the rotor  102  may be in mechanical and electrical contact with a shaft  104 , which may provide linkage for rotation, and may provide a rotor inner diameter connection surface. In example embodiments, the rotor may include an outer diameter connection surface  108 . In accordance with example embodiments, a voltage potential may be induced between the inner diameter (in electrical connection with the shaft  104 , for example) and the outer diameter connection surface  108 . The voltage polarity is dependent on the direction of rotation and the orientation of the magnetic field with respect to the rotor rotation. The voltage magnitude is a function of the square of the rotor radius, the rotation speed, and the magnetic field strength. According to an example embodiment, the rotor radius  110  may be set to provide a certain voltage output for a rotation speed and magnetic field strength. According to other example embodiments, the shaft  104  may be electrically isolated from the rotor  102 , and an inner diameter connection surface may be provided for completing a circuit for which current may flow. 
       FIG. 2  is a side-view depiction of an illustrative homopolar generator with an integral battery  200 , according to an example embodiment. In this example embodiment, a magnet assembly, having a north pole  201  and a south pole  202 , may provide a magnetic flux  206  for interaction with the conductive rotor  212 . In an example embodiment, the  201 ,  202  may be joined by an optional return path  208  to assist in aiding return flux  210  and to reduce the magnetic reluctance associated with the magnetic flux path. According to example embodiments, the magnets, as described herein, may have a sufficient diameter to produce a magnetic field with a diameter that is larger than the diameter of the rotor so that the entire rotor is exposed to the magnetic field. According to example embodiments, multiple permanent magnets may be arranged, for example, in an adjacent north-south-north-south configuration, or with intervening components between the magnets. 
     According to one example embodiment, the magnet assembly may be mechanically separated from the shaft  204  and mounted separately so that the shaft  204  and other attached components may rotate independently from the magnet assembly. In another example embodiment, the magnet assembly may be mechanically coupled with the shaft  204 , and the magnet assembly may rotate with the shaft  204 . Certain advantages/disadvantages in terms of weight, inertia, mounting complexity, etc. for example, may provide reasoning for rotating the magnets, or for providing stationary magnets. A surprising result that is not readily apparent from Faraday&#39;s laws is that it does not matter whether the magnetic field rotates or not. In one embodiment, rotating magnets may add to the mass of the generator and may require more inertial energy to spin the rotor while not otherwise changing the outcome in any useful way. However, according to another example embodiment, it may be advantageous to have the extra mass of the spinning magnet for storage of rotational energy. 
     According to example embodiments, the homopolar generator  200  includes a rechargeable battery  216 . In one example embodiment, the rechargeable battery  216  can be fixed to the shaft  204  and/or the conductive rotor  212 , and may rotate with these parts. In another example embodiment, the shaft  204  and/or the conductive rotor  212  can be configured to rotate independent of the rechargeable battery  216 . 
     According to example embodiments, the shaft  218  may provide an inner diameter connection surface for providing a slideable electrical connection with a first electrode brush  218 . In an example embodiment, the conductive rotor  212  can include an outer diameter connection surface (as in  110  of  FIG. 1 ) for providing a slideable electrical connection with a second electrode brush  220 . In accordance with example embodiments, if the rechargeable battery  216  may include two or more outer diameter connection surfaces for slideable electrical connections with battery electrode brushes  222 . According to example embodiments, two brushes may be utilized to provide circuit connection access to the positive and negative terminal of the rechargeable battery. In example embodiments, multiple rechargeable battery cells  216  may be utilized in the homopolar generator charger  200 , each with similar connections for external circuits, as previously described. 
     According to example embodiments, and as will be further explained with reference to  FIGS. 3, 5, and 6 , a switching controller may be used to selectively connect, switch, and/or disconnect circuits associated with the homopolar generator charger  200 . 
     Many other configurations for the rechargeable batteries  216 , the conductive rotor  212 , the magnets  201 ,  202 , and the associated connecting components may be envisioned without departing from the scope of the inventions. For example, it may be advantageous to electrically isolate the shaft  204  from the rest of the mechanism. In such an example embodiment, an optional insulator  214  may be utilized to electrically separate the inner diameter of the conductive rotor  212  from the shaft  204 . In this example embodiment, the first electrode brushes  218  may be configured to contact with an inner diameter of the conductive rotor  212 , at a slideable connection surface on the conductive rotor at a diameter outside the region of the optional insulator  214 . 
       FIG. 3  depicts yet another example embodiment of a homopolar generator  300  having a battery  308  and a switching controller  320  that are operable for rotating with the conductive rotor  306 . In this example embodiment, the magnet  301  may be configured to be stationary, or it may be configured to rotate with the shaft  304 , the conductive rotor  306 , the switching controller  310  and the battery  308 . In this example embodiment, one magnet  301  is depicted having opposing poles  302  in a plane perpendicular to the conductive rotor  306  so that the magnetic lines of flux pass substantially perpendicularly through the conductive rotor. Other example embodiments may include more than one magnet  301  (such as in  FIG. 1 ). 
     The following illustrative example may help provide part of the reasoning for having a direct electrical connection configuration, as shown in  FIG. 3 . A mid-sized, typical homopolar generator may be designed to produce an output of 3 volts at a current of 1000 amperes (3 KW). A slip ring pair with brushes for connecting with the rotor may have a combined series resistance of 0.01 ohm. The I 2 R loss associated with brush connections is 1000 2 ×0.01=10 KW, which is three times greater than the output of the generator. Therefore, the typical homopolar generator almost always ends up being extremely inefficient. According to example embodiments,  FIG. 3  depicts direct electrical connections  320 ,  322  from the conducting rotor to the switching controller  310 , and direct electrical connections  316 ,  318  to/from the battery  308 . According to example embodiment, direct electrical connection may provide low resistance connections among the rotor  306 , controller  320 , and battery  308  so that I 2 R losses may be minimized. 
     In the example embodiment of  FIG. 3 , first electrode brushes  312  and second electrode brushes  314  may be utilized for electrically completing connections from the switching controller  310  to external circuits. For example, the first electrode brush  312  may connect to a ground or negative portion of an external (and non-rotating) circuit, and second electrode brush  314  may connect to a positive portion of the external circuit, or vice versa. 
     According to example embodiments of the invention, the direct connections  316 ,  318 ,  320 ,  322  may provide low resistance connections for charging the battery  308 . In certain example embodiments, the battery  308  may include multiple cells, each with direct connection to the controller  310 . According to an example embodiment, the controller  310  may provide connections for hooking each of the battery cells in series for outputting power at higher voltages, and perhaps lower currents, so that less power is lost at the electrode brushes  312 ,  314 , which provide slideable electrical connections, for example, to non-rotating external circuits. Additional details for this embodiment will be further described in reference to  FIG. 6 . 
       FIG. 4  depicts an example rechargeable battery  400 , having an anode  402  a cathode  404 , a first electrode  406 , and a second electrode  408 . According to an example embodiment, the rechargeable battery  400  may include a separator  410  between the anode  402  and the cathode  404 . According to an example embodiment, the anode and cathode placement may be switched to provide opposite polarity for the battery output electrodes. According to example embodiments, the polarity of the battery, which may depend on the orientation or placement of the anode and cathode, may be matched with the polarity output from the homopolar generator rotor, which depends on the direction of rotation of the rotor, and the orientation of the magnetic field. According to one example embodiment, the rechargeable battery  400  may rotate with the shaft, the rotor, and switching controller. In such an embodiment, the battery electrodes  406 ,  408  may be directly connected to connections associated with a switching controller (as in  FIG. 3 ). In another example embodiment, the battery may be configured to be non-rotating, or to rotate independently from the rotor. In such embodiments, an optional bearing  412  may be utilized so that the shaft may rotate independent of the battery  400 . 
       FIG. 5  depicts an example circuit diagram of a homopolar generator charger  500  with a non-rotating switching controller  506 . In this example embodiment, a motor  530  may be utilized to turn the rotor  502 . (The magnetic field is not shown in this diagram, but it is assumed present with the correct orientation). According to an example embodiment, a battery  504  (or optionally, two or more cells as indicated by the dashed lines) may be selectively connected to the rotor  502  or to output connections  516 ,  518 ,  520 ,  522  via battery brushes  512 ,  514 , and/or the rotor outer brush  510  and shaft brush  508 . In an example embodiment, the switching controller  506  may connect the rotor positive portion to an output  524 , which may be configured for output independent, or in conjunction with the battery output. According to example embodiments, the switching controller may be utilized for connecting two or more battery cells  504  in parallel for charging, and may be operable to isolated cell positive and negative outputs for serial connection of the batteries for higher voltage output. In accordance with example embodiments, the switching controller  506  may electrically disconnect one or more connections with the rotor  502  when the rotor speed falls below a given threshold value, or when charging current associated with the batteries has reached a predetermined value. 
       FIG. 6  depicts an example circuit diagram of a homopolar generator charger  600  with an integrated switching controller  605  and battery or cells  604  that are operable to rotate with the rotor  602 . The example circuit diagram of  FIG. 6  may correspond to a configuration similar to that as shown in  FIG. 3 . According to an example embodiment, a motor  620  may be used to rotate the rotor  602 , the switching controller  605 , and the battery or cells  604 . In other example embodiments, the rotor  602 , switching controller  605 , and the battery or cells  604  may be rotated via components associated with a regenerative braking system. According to an example embodiment, the rotor  602 , switching controller  605 , and the battery or cells  604  rotate in concert and at least some of the electrical connections between these devices may be hard wired. According to an example embodiment, two output brushes  610  may provide an electrical connection from the components that are operable for rotating, to a non-rotating positive output electrode  612  and a non-rotating negative electrode  614 . According to example embodiments, the reduction of brushes may provide power efficiency advantages, as previously discussed. In accordance with certain example embodiments, the output brushes  610  may be placed in close proximity to (or on) the rotor shaft of the homopolar generator charger  600  to reduce friction and to minimize wear. 
     According to example embodiments, the switching controller  605  may include one or more switching networks  607  that may be utilized to selective close and open circuits among the rotor  602 , the battery or cells  604 , and the output brushes  610 . In example embodiments, one or more diodes may be utilized to limit current flow to one direction in any of the circuits. According to example embodiments, relays or other switching devices having high current capacity and low resistance when engaged may be utilized for switching elements in the switching network  607 . In example embodiments, the controller  605  may additionally include a microprocessor  606 , a rotation sensor  608 , a voltage detector  618 , and/or a battery  609 . In another example embodiment, a receiver and/or transmitter may be included in the controller  605  for wireless communication with an external controller. 
     According to an example embodiment, the microprocessor  606  may be utilized for receiving information, and for directing the switching network  607  based upon input such as rotation speed, rotation direction, etc. According to example embodiments, the voltage detector circuit  618  may be used for monitoring the voltage across the battery, one or more cells, and/or the rotor. In example embodiments, the microprocessor  606  may also receive signals from the voltage detector circuit  618  and may direct the switching network  607  accordingly. According to example embodiments, the switching network  607  may connect the battery or cells  604  with the rotor  602  for charging when a voltage across the rotor  602  has reached or exceeded a predetermined value, or when a certain rotational speed has been reached. According to an example embodiment, power may be supplied externally by the homopolar generator charger  600  via output brushes  610  by connecting one or more of the rotor  602 , battery or cells  604  to the output. According to an example embodiment, the rotor  602  may be switched out of circuit and the battery or cells  604  may be connected to the output for supplying power to external devices via the output brushes  610 . According to example embodiments, two or more cells may be connected in series via the switching network  607  to provide power output at an increased voltage. 
     An example method  700  for converting rotational kinetic energy to electrical energy for charging one or more battery cells will now be explained with reference to  FIG. 7 . In block  702 , and according to an example embodiment, the method  700  includes rotating, by a shaft, a rotor in a magnetic flux field to generate current, wherein the rotor comprises an electrically conductive portion having an inner diameter conductive connection surface and an outer diameter conductive connection surface, and wherein a voltage potential is induced between the inner and outer diameter connection surfaces upon rotation in the magnetic flux field. In block  704 , the method  700  includes selectively coupling the generated current from the rotating rotor to terminals of the one or more battery cells, wherein the terminals comprise a positive terminal and a negative terminal, and wherein the positive terminal and a negative terminal are electrically connected to respective inner and outer, or outer and inner diameter connection surfaces, wherein the at least one battery cell is mounted substantially coaxially with respect to the shaft. The method  700  ends after block  704 . 
     According to example embodiments, brushes may be utilized for making electrical connections of surfaces on the rotor, controller, and/or battery. According to example embodiments, such surfaces may include slip rings that may provide conductive surfaces for which the brushes may make electrical contact with portions of the rotor, controller, and/or battery. In example embodiments, the brushes may include metal fibers, carbon compounds, or conductive liquids, such a liquid metal. 
     According to example embodiments, certain technical effects can be provided, such as creating certain systems, methods, and apparatus that provide efficient utilization of energy conversion. Example embodiments of the invention can provide the further technical effects of providing systems, methods, and apparatus for providing high currents for charging battery cells. 
     In example embodiments of the invention, the homopolar generator charger  200 ,  300 ,  500 ,  600  may include any number of hardware and/or software applications that are executed to facilitate any of the operations. 
     In example embodiments, one or more I/O interfaces may facilitate communication between the homopolar generator charger  200 ,  300 ,  500 ,  600 , and one or more input/output devices. The one or more I/O interfaces may be utilized to receive or collect data and/or user instructions from a wide variety of input devices. Received data may be processed by one or more computer processors as desired in various embodiments of the invention and/or stored in one or more memory devices. 
     One or more network interfaces may facilitate connection of the homopolar generator charger inputs  200 ,  300 ,  500 ,  600  and outputs to one or more suitable networks and/or connections; for example, the connections that facilitate communication with any number of sensors associated with the system. The one or more network interfaces may further facilitate connection to one or more suitable networks; for example, a local area network, a wide area network, the Internet, a cellular network, a radio frequency network, a Bluetooth™ (Owned by Telefonaktiebolaget LM Ericsson) enabled network, a Wi-Fi™ (owned by Wi-Fi Alliance) enabled network, a satellite-based network any wired network, any wireless network, etc., for communication with external devices and/or systems. 
     As desired, embodiments of the invention may include the homopolar generator charger  200 ,  300 ,  500 ,  600 , with more or less of the components illustrated in  FIGS. 1-6 . 
     According to additional example embodiments, the rotor may include a composite conductive structure. For example, the rotor may be made with materials including, but not limited to fiberglass, sintered metals, alloys, graphite composites, etc. According to example embodiments, the rotor conductive surface or disk may be evaporated or deposited onto a base material. According to example embodiments, the rotor may include a copper outer casing. According to example embodiments, the homopolar generator charger may include an outer casing that may be made of various non-conducting materials with the required structural properties. In example embodiments the homopolar generator may include electrodes or electrical connection regions or surfaces that are made from of nickel oxyhydroxide and/or a hydrogen absorbing alloy. According to example embodiments, two or more rotors can be stacked to provide different configurations, redundancy, and/or increased power output capacity. 
     According to example embodiments, the homopolar generator charger may provide pulsed current output. For example, a connecting circuit may be completed and opened in succession to provide a current path between the rotor inner and outer conductive regions and other components. In an example embodiment, during the period when the connecting circuit is open, a charge differential may build on the rotor until a balance of charge is met. Closing the circuit may allow the electrons to flow, similar to a capacitor, until charge is depleted. 
     According to example embodiments, frictional losses due to rotation of the rotor, battery, and other associated rotating components may be reduced by dimpling any surface where there is no brush or contact. This includes unused areas of the shaft and areas that have clearance for air to pass between, and can be applied to the facing surfaces of the magnet array and magnets themselves. According to example embodiments, drag may be reduced via the dimpling by creating a boundary layer of turbulent air at exposed surfaces. In an example embodiment, dimpling may also be utilized to enhance heat dissipation. 
     According to an example embodiment, the homopolar generator charger&#39;s rotor may comprise a solid copper disk and a battery as previously described. Experiments have shown that an 18 inch by ¼ inch solid copper rotor is capable of sustaining 1500 amps in a field of 13000 gauss. In an example embodiment, copper may be applied to the outer surfaces of the rotor via electroplating. In an example embodiment, the rotor may be made from a solid copper disk or from an alloy. In an example embodiment, a solid shaft made from a similar alloy, and configured to pass through the disk center, may facilitate the conduction of electricity and maintain the structural integrity of the unit. 
     In example embodiments, the rotor and shaft can be supported by various means. According to an example embodiment, a housing or structure may support the rotor assembly in position and may to allow the rotor to rotate on a common axis. According to an example embodiment, ends of the rotor may be supported on roller bearings. In an example embodiment, pressurized gas, oil, or magnetic suspension may be utilized to reduce mechanical resistance. According to example embodiments, ceramics and other non-conducting components may be utilized to eliminate current flow in unwanted areas. 
     In accordance with example embodiments, current may be supplied to external component, or between components associated with the homopolar generator via brushes. In example embodiments, solid copper, graphite, sintered, liquid metal, or other brushes may be mounted in standard brass holders on each side of the rotor&#39;s shaft and on the periphery of the rotor conductor or disk. 
     According to example embodiments, the generated current and/or voltage output from the homopolar generator rotor may be dependent on the magnitude of the magnetic field, the square of the conductor&#39;s radius immersed in the magnetic field of a given magnitude, and the angular velocity of the conductive portion of the rotor. Other factors affecting output include composition and size of the conductor or rotor, mechanical resistance, magnetic coupling with exterior objects, brush materials, etc. Eddy currents allowed to flow in a portion of the disk or conductor outside the field can reduce the efficiency. 
     According to another example embodiment, portions of the rotor may include embedded wound coils, each connected in a manner to produce a voltage and current output. According to an example embodiment, a stator, comprising multiple stationary magnets arranged in alternating north-south-north-south ring configuration, may be mounted around the center of a larger magnet. In an example embodiment, a drive motor may be integrated with the rotor. In an example embodiment, a wire-wound generator may be utilized as a motor. In accordance with example embodiments, regenerative systems, which may include a generator/motor may be used in conjunction with the homopolar generator charger. 
     According to this example embodiment, an inner generator/motor may be utilized in conjunction with the rotor of the homopolar generator. For example, an inner generator/motor may comprise a hub-type of wire-wound motor. In accordance with an example embodiment, when the rotor is decelerating or coasting, the rotor may act as a flywheel. In an example embodiment, kinetic energy from the rotor assembly may provide mechanical leverage when the motor is switched to generating mode, such as in a regenerative system. Accordingly, the rotor in the regenerative mode may have certain mechanical advantage due to its proximity to the center of the shaft. However it may have the classic back torque or back electromotive force associated with standard generators. The back torque or back electromotive force may be minimal if designed for low voltage of 3 volts or less. 
     According to example embodiments, outer (non-rotating) magnets surrounding the inner (rotating) magnets may be utilized for producing the high currents that are typically associated with a homopolar generator with a solid conductor disc rotor. According to example embodiments, rectification may be utilized for the inner magnet portion, and the outer portion associated with the stationary part may produce direct current. 
     Example embodiments may utilize a circumferentially segmented rotor made of at least two conductors isolated from each other at their peripheries. Other example embodiments may include a rotor having a conductor shaped in the form of a spiral. 
     In accordance with an example embodiment, the homopolar generator charger may include a composite copper disk mounted inside a magnetically closed metal housing. In an example embodiment, magnets may be attached to the inside of the housing. For example, the housing may include two half pieces, having parabolic-shape, or other suitable shape. In example embodiments, bearings may be mounted in the center of each half, allowing the magnetic flux from ends of the single or stacked magnets to couple back through the housing. This arrangement may reduce external fields and magnetic coupling of exterior ferrous objects. According to an example embodiment, the housing may be made of soft or cast iron. Example embodiments of the housings may be heat treated for fixing dipole alignment (or randomization) of the material. According to an example embodiment, nickel may be included in the housing material to reduce hysteresis. In other example embodiments, laminated structures may be employed reduce induced eddy currents. In an example embodiment, a brush system (solid or liquid) may be mounted and isolated electrically at the center between the halves of the housing structure. In an example embodiment, outer diameter surface of the brush assembly may be constructed from the same materials as the housing halves to allow the magnetic flux a point of return. 
     According to an example embodiment, the rotor may include integrated rings of individual rechargeable batteries or cells separated by insulators. In one example embodiment, the innermost battery or cell may be placed in a ring adjacent to the shaft. In an example embodiment, the innermost battery or cell may be surrounded radially by a second battery or cell, and so-forth to a desired diameter. According to an example embodiment, as the circumference is increased, the radial thickness of each cell or battery may be modified to keep each battery or cell ring at approximately the same internal resistance. 
     According to another example embodiment, a straight shaft design may be utilized in high speed applications ranging from approximately 10,000 to approximately 100,000 revolutions per minute. In this embodiment, a shaft may be made of neodymium-iron-boron being solid in construction but with appropriate thickness to carry high currents without overheating. Any number of raised surfaces can be machined into the outer surface of the rotor shaft. According to example embodiment, the raised machined surfaces may be located over the center of any opposing magnetic fields. In an example embodiment, the surface of the shaft may be electroplated with conductive metal to reduce oxidation and provide points of brush contact for current output. According to an example embodiment, the shaft may be capped with bearing supports of magnetic material or ferrous ends for oil, air, and gas or magnetically floated. In accordance with an example embodiment, the shaft, when rotated at high speed, may maintain a negative polarity on the shaft center with charge separation occurring at or near the surface of the shaft. Accordingly, charge separation may occur at the point of the centerline where the magnetic flux is closest to zero. According to example embodiment, brush slots may be filled with a liquid metal and capped under slight pressure, and lugs may be milled into these areas for current extraction. In accordance with an example embodiment, the outer housing may be made from cast iron to close the unused poles and force the internal magnetic flux lines compress and concentrate in the area where outer raised areas of the shaft may intersect the compressed fields at 90 degrees. In an example embodiment, this type of generator can be used in high temperature applications, such as in turbine exhaust systems, and may recover energy form systems that have exhaust as a byproduct of operation. Any enclosed tube in which a liquid, gas, or vapor flows from a high potential to a lower potential is a candidate for this type of generator. 
     According to an example embodiment, a rotor assembly made of printed circuit material may be utilized to provide a voltage potential or current source. In an example embodiment, the printed circuit rotor may be mounted to shaft. In an example embodiment, the printed circuit rotor may be mounted adjacent to another rotor. Example embodiments may include a multilayer printed circuit rotor. Example embodiments may include an integrated switching controller with or adjacent to the printed circuit rotor. The printed circuit rotor may provide a lightweight design and may allow for complex conductive patterns on the rotor. 
     Example embodiments may include a conducting disk composed of a conductor or materials that conduct electricity and mounted on a shaft or axle so that it can be rotated within the fields of one or more permanent magnets. According to example embodiments, the magnets have a sufficient diameter to produce a field that is larger than the diameter of the disk or rotor. In an example embodiment, the disk may include a composite copper rotor or other conductor in which current and voltage is known to flow when rotated in a magnetic field. The rotor may include an inner and outer diameter conducting rings or surfaces, as describe previously. The area between the inner and outer diameter conducting rings or surfaces may include layers of capacitor components in a radial orientation. In one example embodiment, the negative terminal of the capacitor component may be connected at the center, and positive terminal may be configured for electrical connection at the outer radius. According to example embodiments, the capacitor may include two conductors separated by a dielectric or non-conductive region or insulator. The conductors thus hold equal and opposite charges on their inner and outer surfaces, and the dielectric develops an electric field. According to example embodiments, the capacitor parts may be arranged in a cylindrical form. 
     According to example embodiment, rotor systems in a cylindrical shape may have a shaft made from NdFeB material or is cast in the required shape. In example embodiments, beryllium or copper conductors can be fitted to the NdFeB shaft to allow for current extraction directly from the ends. 
     Example embodiments, may include both the shaft and rotor combination to include both the north and south pole, with a conductor of copper or other material fit to the center of the magnetic rotor. Such an embodiment, may draw current through the magnet and shaft, being the conductor in combination. This example embodiment may result in a configuration similar to a standard rotor system, but it may include composite NdFeB for current conduction. Example embodiments may include electroplating the assembly with highly conductive materials prior to magnetization to both protect the NdFeB from the elements and provide a conductive path for the flow of current, all in one assembly. The assembly may then be magnetized through its thickness one side being north and the other being south. The conducting ring being mounted in its centerline may provide the highest concentration of field strengths, as the highest fields are on the surface and interiors of the magnets. In an example embodiment, the rotor section is magnetized. In this configuration, the north side may rotate in the same direction as the south. 
     In accordance with example embodiments, the rotor system may be mounted on or in many enclosure configurations, and may have either a closed magnetic flux circuit or open magnetic circuit. According to one example embodiment, a rotor may be supported by non-magnetic pedestals, but may utilize permanent- or electro-magnets. In one example, magnets may be approximately six inches in diameter, one half inch thick, and may include a one and three-eighths inch hole in the center for the shaft to pass through. In an example embodiment, six magnets may be used. According to an example embodiment, the first magnets on each side of a divided housing may be bolted to the housing. The next two magnets may be magnetically coupled north to south or vice versa, three on each side. This arrangement may be utilized to increase and guide the magnetic field. In an example embodiment, two halves of a housing may be assembled in a way that may subsequently receive additional components, including the rotor, shaft, rechargeable battery, switching controller, etc. 
     In accordance with example embodiments presented herein, it should be understood that the housings and materials mentioned are not only subject to electromagnetic or permanent magnet fields, but also fields that are created by the flow of current within the system. All of the factors that govern permanent sources of fields may also apply to fields created by current flow. In example embodiments, shielding may be utilized to prevent or guide certain forces. For example, some materials, such as non-ferrous brushes and copper conductors, may become attracted to each other through the magnetic force created by current flow, and may need to be shielded to prevent unwanted forces. 
     In accordance with example embodiments, the rotating portion of the homopolar generator charger may include a stack of disk shaped rotors between stationary or affixed magnets, so that the magnets rotate with the shaft. In this example configuration, the rotor disk, batter disk, magnet disk(s), and any switching control circuitry may be mounted on a common shaft. 
     Example embodiments may include many options for the type of rechargeable battery or cell to be used in a system, and may be dependent on many factors, such as use or type of application, environment or generator configuration, battery resistance, charge absorption over time, temperature, and issues such as electrolyte separation due to centrifugal forces. 
     Nickel metal hydride (NmH) batteries may be utilized as rechargeable batteries, according to an example embodiment. Such batteries may have a low internal resistance, and may have high durability. Lithium-based cells (for example, lithium-ion, lithium-polymer, etc.) may be utilized as rechargeable batteries, according to another example embodiment. According to one example embodiment, a dual battery bank system may be used, for example, to provide power from one bank while another bank is charging. According to example embodiment, a switching system, such as the ones previously describe, may be used for selective routing of internal conductors. 
     According to an example embodiment, an internal or external bank of batteries may be charged at low voltage and high current using the homopolar generator charger. According to this example embodiment, batteries may be charged as individual cells in parallel. According to an example embodiment, the bank can include individual cells. For example, NiM cells may have nominal associated voltages of approximately 1.2 to 1.5 volt. Li cells may have nominal associated voltages in the range of approximately 2.8 to 3.3 volts. Bank size or number of cells may be determined by the amount of energy needed by the load for a given time. A generator size may also be determined based on the size of the battery bank. For example, 180 1.2 volt batteries may require approximately 300 amps to recover from a 90% discharge. An example generator capable of providing the 300 amps and at a voltage of 1.5 volts, according to embodiments, could conceivably recharge the bank in 15 minutes. If the depth of discharge is less, then the time required to reach 100% charge may be reduced. For comparison purposes, a bank of this size can take from 2 to 20 hours to recharge by conventional means, particularly if the batteries are charged in series. 
     According to example embodiments, after reaching full (or near full charge), the battery bank may be switched to a series configuration to provide an increased voltage output for powering devices. In an example when a discharge limit is reached, the bank may be switched back to parallel and current may be directed to charge the bank. 
     According to an example embodiment, and as previously discussed, a battery or cell bank may be rotated with the rotor. In an example embodiment, a disk shaped battery may include a center hole being either a positive or negative pole. In an example embodiment, the battery may be approximately 8 inches in diameter, approximately 5/16 of an inch thick with approximately a 1 inch diameter hole in the center for the shaft to pass through, or for attachment to the shaft. In an example embodiment, the outer shell of the battery may be copper or copper clad to form the rotor. According to an example embodiment, the negative terminal of the battery may include an electrode composed of a hydrogen absorbing alloy. The electrode may be in a grid or it may be perforated to increase its surface area. According to example embodiments, the positive electrode can include nickel oxyhydroxide. According to an example embodiment, a disk battery of this size would weigh approximately 2.5 pounds. Each battery may be capable of 800 to 1000 watts per kilogram specific power. 
     According to example embodiments, one or more rotors may be mounted on a common shaft. Each may be separated by a disk shaped magnet with the poles on the faces north and south. Such an example configuration may also be connected in series to provide higher voltage potentials but at lower amperage capacity. The reverse is also true with lower potential and higher amperage capacity. 
     According to example embodiments, the applications for the homopolar generator charger system may include, but are not limited to wind energy harnessing, automotive electric vehicle industries, geothermal systems, hydropower, tidal and wave energy harnessing, uninterruptable power supplies, emergency power, etc. For example, instead of large generators producing high speed and high voltage potentials, the generator could be a low speed, high current design that could provide current in line with the nature of high capacity cells. Advantages may include a reduction weight, operation under light loads or cruising speeds, and high efficiency. 
     While certain embodiments of the invention have been described in connection with what is presently considered to be the most practical and various embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. 
     This written description uses examples to disclose certain embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice certain embodiments of the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of certain embodiments of the invention is defined in the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.