Abstract:
A method of increasing the power output of existing permanent magnet motors along with apparatus is disclosed. Increased power output is achieved by more completely utilizing the magnetic field of motor permanent magnets during running. The apparatus is external to the motor and therefore eliminates the need for modifications to the motor itself. The method involves providing a source of power to a permanent magnet motor which is capable of demagnetizing the motor permanent magnets at stall, and reducing the power at start up to a level sufficient to prevent demagnetization. Full power to the motor is provided when the motor speed reaches a level sufficient to prevent demagnetization of the permanent magnets.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 09/440,490 filed Nov. 15, 1999, now U.S. Pat. No. 6,194,799 issued Feb. 27, 2001, which application is divisional application of U.S. patent application Ser. No. 09/088,096 filed Jun. 1, 1998, now U.S. Pat. No. 6,037,692 on Mar. 14, 2000, which application is a continuation-in-part application of U.S. patent application Ser. No. 08/991,926 filed Dec. 16, 1997, now U.S. Pat. No. 5,903,118, issued May 11, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electric motors and, more particularly, to direct current electric motors suitable for reliably and efficiently powering electric vehicles and industrial machinery. 
     2. Description of Related Art 
     There are numerous electric motors available for propelling electric automobiles. These include both direct current (DC) motors designed to drive directly off of the batteries and alternating current (AC) motors which require electrical circuitry for converting the DC power in the batteries to AC power. The most efficient of these AC motors requires three or more phase power. 
     Such motors have a high power-to-weight ratio, can be made to run efficiently, and are inherently reliable because of their brushless design. A disadvantage of such motors is the fact that the battery power must be first converted to AC before it can be used by the motor. This disadvantage shows up in the need for complex circuitry. This is especially true for AC motors having three or more phases. Along with the need for complex circuitry is the fact that the failure of even a single electrical component in the system can result in total failure of the drive circuitry for producing AC power. This results in DC electric power in the batteries, and a motor that requires AC power. This renders the entire drive system useless. 
     Therefore, such drive systems suffer from the potential of leaving the driver stranded. Despite these obstacles, companies such as AC Propulsion Inc. have made considerable advances in the use of AC motors in electric cars. In particular, high power to weight ratios have been achieved. 
     In the powering of industrial machinery, in many applications it is desirable to have an electric motor that has considerable amounts of torque and power at relatively low RPM values. This is normally achieved by gearing the motor down, however this practice results in added moving parts, increased mechanical losses, and adds cost and complexity to the overall system. In general DC electric motors have good torque characteristics which make them ideal for use in many industrial applications. In general with DC electric motors, the more mechanical drag on the motor, the more torque is produced. In this respect such motors are ideal for propelling electric cars as well. This is especially true if one wants to drive the wheels of such a vehicle directly by employing a motor in the wheel hub. There are several reasons why DC electric motors are advantageous. 
     DC electric motors require little circuitry to drive them from batteries. In some cases they can be wired directly with only a switch to turn the system on and off. Another advantage offered by DC electric motors is the fact that such motors do not require starting circuitry in the way that many AC motors do. 
     The first electric cars were produced at the turn of the century and were powered by DC electric motors. Such motors utilized two sets of electromagnets to produce their torque. One set was mounted to the inside of the motor casing. These electromagnets had one set of poles facing inward, and the other set of poles against the steel casing to magnetically connect them in series. The motor casing with its electromagnets made up the stator portion of the motor. When power was on, these electromagnets maintained the same field. At each end of the motor casing were end caps having holes which were centrally located which supported a bushing or bearing through which the rotational portion (or rotor) was supported. The rotor consisted of a round shaft having a larger diameter set of electromagnet windings wound onto an iron core. The ends of the rotor windings were fixed to conductive copper strips that were insulated from each other and the motor casing using resin or other suitable insulating material. A set of brushes which were usually made of graphite pushed up against the copper strips in the rotor to make electrical contact while also allowing the rotor to rotate. The position of the brushes relative to the stator electromagnet windings was always set so that the proper rotor electromagnets were turned on at the appropriate times by the brushes to always magnetically drive the rotor in the same direction (i.e., by interaction of the stator magnetic field with the magnetic field of the electromagnets in the rotor). 
     While these motors were suitable for powering both electric cars, as well as industrial equipment, Their efficiency was somewhat limited by the fact that power losses occurred in both sets of electromagnets due to the resistance of their windings. 
     In the early 1930s, the General Electric Company developed the first permanent magnets that were strong enough to replace one set of electromagnet windings in DC motors. This Permanent magnet material was called Alnico, and soon several grades were made commercially available. Shortly thereafter, the first useful permanent magnet motors began to appear. These is motors basically used permanent magnets to replace the stator electromagnets. While these motors had an increased efficiency when compared to their predecessors, they suffered from the possibility of demagnetization of the permanent magnets if the electromagnetic field in the rotor exceeded the “coercive force” (a measure of the resistance to demagnetization of permanent magnets) of the permanent magnets in the stator. To partially alleviate this problem, stronger ceramic permanent magnets were developed, and still stronger magnets called “Rare Earth Magnets” are among the most recent developments. 
     All DC permanent magnet motors run the risk of demagnetization of their permanent magnets if the electromagnetic field of the windings exceed the coercive force of the permanent magnets. To alleviate this problem, a maximum safe operating voltage for any DC permanent magnet motor is specified which under maximum power conditions (i.e., at stall) the resistance of the electromagnet windings will be high enough to prevent a flow of current through the electromagnet sufficient to cause irreversible damage to the permanent magnets. This current is considerably greater than the normal operating current, and for this reason, normal operating conditions for traditional permanent magnet DC electric motors only utilize a fraction of their true power capabilities based on their permanent magnets. In fact, most of these motors only utilize between 10% and 25% of their true potential. 
     The wire diameter used in winding an electromagnet core basically determines the magnetization force in ampere-turns for a given cross-sectional core diameter at a given voltage. Increasing the number of turns reduces the number of amperes that will flow through the coil, but increases the number of turns thus, maintaining the same number of ampere-turns. In order to more effectively use the permanent magnets of a permanent magnet motor under normal running conditions (i.e., at 10% to 25% of stall current) electromagnet windings must be activated that are more than capable of demagnetizing the permanent magnets in the motor under the conditions of stall. One way to accomplish this is to wind the electromagnet in layers and using thinner wire successively in the outer layers. On start up, all the layers of wire in the electromagnet are used. The resistance of the thinner outer wire prevents excessive currents in the motor thus preventing demagnetization of the motor permanent magnets. Once the motor RPM value reaches a safe level, the outer layers are shunted, thus increasing ampere turns in the motor and increasing the utilization of the motor permanent magnets. An interlock is also provided that prevents accidental activation of the shunt mechanism under stall or low RPM conditions. Other methods may be employed to wind electromagnet cores providing this type of electromagnet. Also included is twisting two or more strands of a given thickness insulated electromagnet wire together and winding the core. At one end the two strands are connected. This becomes the common. At the other end, the two leads are kept separate. On motor start up, only one lead is connected. Once motor RPM values reach a safe level, the second lead is connected to the first thereby increasing the utilization of the permanent magnets by providing more ampere-turns in the motor electromagnet assembly. 
     This increased utilization of permanent magnets during running conditions results in an electric motor having exceptionally high torque values. The example outlined below will be used to further illustrate this point. 
     Ametek Corporation is a major manufacturer of electric motors. They manufacture a DC permanent magnet motor which is nominally rated at 24 volts. # 116281-00. It is reversible and has a no load speed of 980 RPM. Measurement of the armature resistance under stall conditions gives 2.4 ohms. According to the manufacturers specifications, it is desirable to run this motor at 750 RPM. This value represents about 25% of stall torque at 24 volts input. Under these conditions, 2.75 amperes of current flow through the motor windings. The voltage drop is equal to the Resistance in ohms times the current in amperes. This is equal to 2.4 ohms×2.75 amperes =6.6 volts. This leaves 17.4 volts for contributing to mechanical work giving the motor an efficiency of about 73%. The mechanical output when using this motor under the manufacturers recommended voltage, torque, and RPM values is 2.75 amperes×24 volts×0.73 efficiency factor to give 48 watts or about 0.063 horsepower. Running under the conditions of less torque increases motor efficiency however is detrimental to power output. Loading down the motor to increase torque has the effect of trading torque for RPM which results in virtually no increase in mechanical work output accompanied by a rapid increase in power losses in the motor windings. 
     Accordingly, The manufacturer also provided the maximum current before demagnetization occurs in the motor. This occurs at a current of 20 amperes through the windings. Note the fact that up to 20 amperes can be delivered to the motor before damaging the permanent magnets, but the manufacturer also specifies the best load value to run the motor at is 2.75 amperes. Therefore during normal running conditions, only 13.7% of the capability of the permanent magnets are utilized. This indicates that under the proper conditions that this motor can put out 7.3 times this torque value at this RPM value before demagnetizing the stator permanent magnets. 
     As is, this motor can withstand 20 amperes through its electromagnet windings before demagnetization effects destroy the stator permanent magnets. With an armature resistance of 2.4 ohms (measured at stall) this gives a maximum safe operating voltage of 48 volts without the risk of damaging the stator permanent magnets. Of course other factors need to be considered before exceeding the manufacturers specifications, but this electric motor can handle stall at 48 volts before demagnetizing the stator permanent magnets. This gives a power rating considerably higher than the original manufacturers specifications. If one wants to run this particular motor at 48 volts and at 25% of stall torque (Maximum mechanical work output before excessive voltage drops across the windings occur) at 48 volts, and about 5 amperes, 240 watts of power will be delivered to the motor at 1,500 RPM with an approximate efficiency of 75%, producing 180 watts of mechanical work and 60 watts of waste heat being generated in the motor windings. In this case the permanent magnet utilization during running is 25% of their true capability. If one wants to increase the torque output at this RPM value, it is necessary to further utilize the stator permanent magnets during running. This can be accomplished using motor windings in the armature that are more than capable of demagnetizing the stator permanent magnets under stall conditions, and not fully activating these windings until the motor RPM reaches a safe value that will not demagnetize the stator permanent magnets. The following theoretical analysis will illustrate this point. 
     An arbitrary number of 100 turns is chosen for the wire that wraps the electromagnet core. This gives a value of 2,000 ampere-turns before demagnetization occurs. A wire diameter is chosen to wrap the electromagnet rotor core that is half the resistance of the original wire. If the same number of turns are used, (100) an armature resistance of 1.2 ohms would be the result. 
     Since the same number of turns is used, if 48 volts is applied to the armature windings under stall conditions, 4,000 ampere-turns would result. Twice the magnetic field needed to demagnetize a the stator permanent magnets (assuming that core saturation effects are negligible). Now this particular motor as is would not be suitable for running at 48 volts because if even 50% of stall torque is achieved, the stator permanent magnets will be at least partially demagnetized. A second set of electromagnet windings is employed in series with the first set of windings using wire of three times the electrical resistance as the first original set. This set of windings is then wound with the same number of turns (100) as the first set giving a resistance of 3.6 ohms. The total resistance of the two windings combined is 4.8 ohms. Since the electromagnet core has twice the number of original turns, (200) in terms of demagnetization (2000 ampere-turns) this motor would have a safe operating current of 10 amperes. With an armature resistance of 4.8 ohms, a maximum operating voltage of 48 volts can be employed under the conditions of stall without demagnetizing the stator permanent magnets. 
     Now assume that at start up, this particular motor is connected to a 48 volt power source. 
     At start up, all of the windings are activated causing a current of 10 amperes to flow. 2,000 ampere-turns results in the electromagnet which is just shy of the magnetic field needed to demagnetize the stator permanent magnets. The rotor under this strong magnetic field starts to spin rapidly, and the current along with its associated magnetic field starts to weaken. At some RPM value, it is now safe to shunt out the outer high resistance turns of wire thus activating only the lower resistance inner turns. Since 25% of stall current is the desired operating range, and the rotor electromagnets have the same number of turns as the original motor, at 1,500 RPM the motor efficiency is 75%, but the torque is twice the value as the original motor, and the permanent magnets are being utilized at 50% instead of 25%. This motor is now putting out twice the power as it was originally. 480 watts of input power is providing 360 watts of mechanical work accompanied by 120 watts of waste heat. This method of increasing the power output of permanent magnet motors is quite effective. This process however needs to be made user friendly. This requires that the end user of such motors does not have to think about damaging such motors by fully activating the lower resistance motor windings. In order to accomplish this end, interlocking circuitry is needed in order to prevent the accidental demagnetization of permanent magnets in these permanent magnet motors. 
     Another example of how this approach can yield positive results would be to employ the thick inner windings of the previous example with its thinner associated outer windings, but only run the motor at 12.5% of stall instead of 25% of stall. In this way, this electric motor would utilize the permanent magnets by only 25%, the same utilization as the original motor without these modified windings. The motor efficiency, however would be significantly improved from about 75% to 88%. As now the thicker electromagnet windings would have less resistive losses. Of course the same precautions to guard against demagnetizing the permanent magnets would have to be taken. 
     In these particular cases, the connections to the electromagnet windings are difficult to achieve because the electromagnet is embedded into the rotary part of the motor. Not that this cannot be achieved, it can, in at least two different ways. 
     In the first method, two different and complete sets of both brushes and commutators may be employed. This is not a preferred method of implementing the high magnetic utilization aspects of this invention. Brushes and commutators are a major source of motor wear and maintenance problems. Adding on another set would add complication and increase the overall need for motor maintenance. A better approach would be to employ an internal centrifugal switch that switched the motor windings only when the RPM value reached a safe level. Such switches are commonly used to lock out motor starter windings in many single phase AC induction motors. Although two methods of using this system are described above, it is far easier implemented in DC permanent magnet motors of brushless design. In such electric motors, the electromagnets make up the stationary part of the motor or stator, and the permanent magnets make up the rotating portion of the motor or rotor. 
     Brushless DC electric motors are permanent magnet motors which employ their permanent magnets into the rotating portion (rotor) of the motor and their electromagnets into the stationary portion (stator) of the motor. This results in a design which is inverted from traditional permanent magnet motors. Because the electromagnets used in such motors are stationary, no electrical power needs to be provided to any moving parts. This elimination of brush timed commutators is accomplished by switching arrangements which are comprised of a rotor position sensor and transistor switching circuitry. Several methods may be employed for sensing rotor position including Hall effect sensors, and photocell gates. Transistor switching circuitry usually consists of transistors for the actual switching of power to the stationary electromagnets along with diode protecting circuitry which protects the transistors from transient back voltage spikes that are often associated with the rapid switching of electromagnets. 
     Another alternative is to construct a DC permanent magnet motor having the permanent magnets in the rotor and the electromagnets in the stator as is done with brushless designs but use a brush system for timing. The timing signal is then amplified electronically using transistors. This eliminates many of the problems in brush timed motors by significantly reducing the power that flows through the brush commutator system. This allows the brushes to be made from such materials as conductive kapton polyimide film, and also for the use of commutators made from copper clad circuit board material. With this type of hybrid brush timing system, keeping the inverted design features normally found in brushless motors is beneficial when employing multiple winding electromagnets. 
     Brushless permanent magnet motors are ideal for increasing permanent magnet utilization during running by employing the teachings of this invention. With the electromagnets in the stator instead of the rotor, the use of multiple electromagnet windings is easily achieved. In addition since the switching of the electromagnets is now achieved using electrical switching circuitry, interlocking of the individual electromagnet windings becomes a relatively easy task to perform. Speed sensing is critical as it is now used as a determining factor in the interlocking of various electromagnet winding configurations. This serves the all important function of protecting the permanent magnets from accidental demagnetization. Several speed sensing and interlocking approaches may be used. For example, for relatively large motors, a small electric generator may be placed onto the power output shaft of the motor and wired to a relay which closes the appropriate contacts at a predetermined generator output voltage. This system is a good choice because if any of the speed sensing components fail, the high power electromagnet windings are interlocked out and the motor while not being able to go into the high power mode will not be damaged by the accidental premature activation of these high power electromagnet windings. Another similar option for speed sensing is to place a small coil of wire on a ferromagnetic core which is placed close enough to the permanent magnet rotor to generate an output voltage which is proportional to speed. This sensor then becomes the electromagnet portion of a permanent magnet generator which uses the rotating rotor permanent magnets as its own. 
     According to another aspect of this invention a high power DC electric motor which is suitable for powering electric automobiles as well as industrial machinery is provided. This particular electric motor describes the use of a large diameter planar rotor employing built in air moving vanes to provide cooling to stator electromagnets. 
     All electric motors have resistive losses in their electromagnet windings which generate considerable amounts of heat. Because of this generation of heat, many motors both AC and DC, are equipped with a small fan blade mounted onto the motor shaft on the inside of the motor to move air through the motor for the purposes of cooling. In the case of DC motors, the greatest amount of heat is generated under high load conditions. Because of this fact, coupled with the fact that under such conditions motor RPM values are low, insufficient volumes of air are available to adequately cool the motor. This leads to the undesirable risk of overheating the motor under heavy load conditions. Because of this, it is often practice to mount an external fan powered by a separate power source to continuously blow high volumes of air through the motor. Although efficient for motor cooling under low RPM heavy load conditions, the extra fan motor adds to the complication of the system. 
     In addition to the overheating issue, the overall power of DC permanent magnet motors is proportional to the amount of permanent magnet material that can be magnetically cycled through the field produced by the electromagnets. To achieve a high rate of magnetic cycling at relatively low RPM values, employing a large diameter rotor is beneficial. 
     Increasing the rotor diameter increases the surface speed at the edge allowing a high volume of airflow to be easily achieved by adding air moving surfaces about the periphery. This airflow is needed to cool the motor. For high power output applications, further cooling may be necessary. Blades, rotary vanes, or even an internal turbofan can be added to achieve this. 
     Several electromagnet to permanent magnet geometries may be employed. For example, the permanent magnets may be placed facing outward in a radial configuration at the periphery of a large diameter disc. With this permanent magnet configuration, the electromagnets are placed around the periphery with their poles facing inward in a radial direction. In this particular situation, rotary vanes could be added around the periphery on the top side and/or the bottom side of the permanent magnets for the purposes of moving air over the exposed top and bottom surfaces of the electromagnets in the stator. Another possibility is to use a star shaped electromagnet in the center, and use a ring of permanent magnets that travels on the outside periphery of the centrally located electromagnets. In this configuration it is best practice to employ a central turbofan design to the rotary portion which pumps air over the central windings from top to bottom. Another geometry which can be employed is to place the permanent magnets into the periphery portion of a large diameter flat disc with their direction of magnetization transversing through the disc. The desired No electromagnet shape in this particular situation is one that forms the shape of a “C” and straddles the periphery of the disc with the permanent magnets traveling through the slot. In this case, air moving vanes can be added which protrude radially past the periphery of the disc to move air within the channel of the electromagnets to provide adequate cooling. One particularly interesting approach to utilizing air cooling with this particular motor geometry is to fasten flexible plastic film vanes to the periphery of the disc. These plastic strips are initially made to protrude from the edge in a radial direction. These flexible plastic strips move modest quantities of air past the electromagnets under low RPM conditions. As the rotor velocity increases, aerodynamic drag bends these strips back. This alters their shape, reducing their drag effect on the rotor, however, enough airflow is still maintained to prevent overheating of the electromagnets. 
     In addition to permanent magnet motors, the large diameter planar rotor geometries employing added air moving surfaces are also suited for use in “Switch Reluctance” motors. Switch reluctance motors are electric motors of brushless design where a non-magnetizable material having a high permeability is employed in the rotor in place of the permanent magnets. These materials include silicon steel, soft iron, magnetically soft ferrite, and others. Such materials become magnetic only when they are in the presence of an externally applied field. The familiar magnetic attraction between a permanent magnet and steel is an example of the principle utilized in switch reluctance motors. In such motors, only attractive forces are generated. Because of this, the switching sequence as well as the spacing of the high permeability material in the rotor is somewhat different from that which is employed in brushless electric motors having permanent magnets. Switch reluctance magnetic attraction works because while the non-magnetizable high permeability material is in the field, it becomes a temporary magnet with induced magnetic poles. Materials having high magnetic permeability lower the overall field energy of the electromagnets by completing their magnetic circuit. This field energy shows up as mechanical work. Although the risk of demagnetization is alleviated in switch reluctance motors, large voltage spikes are produced during electromagnet switching. These spikes represent large amounts of energy which can damage circuit components, create excess heat, and negatively affect motor efficiency. To alleviate this problem, high frequency chopped DC power, or even AC power can be supplied to the electromagnets where the cycle to rate is considerably higher than the motor timing switching rate. In other words, during single electromagnet on times, multiple electric pulses occur. 
     With all of these planar rotor geometries, high surface speeds around the periphery of the rotor are easily achieved along with considerable forces in a radial direction during running. As an example, a 24″ diameter rotor rotating at 3,000 RPM will have a surface speed at the edge of about 200 miles per hour. With 5 pounds of permanent magnets around the periphery, in addition to a couple of pounds of other materials, about 27,000 pounds of centrifugal force would be present in a radial direction. Because of these radial forces, strong materials need to be used in the fabrication of the rotary portions of these large diameter planar rotors. 
     One solution is to employ composite materials such as carbon fiber. These materials are strong and lightweight. They do not easily conduct electricity like metals and therefore would not contribute to inductive losses. With some rotor permanent magnet geometries flat steel sections can be sandwiched on both sides by permanent magnets. With other permanent magnet rotor geometries, a steel band can be used for the purposes of holding the permanent magnets in place as well as magnetically connecting them in series with each other for the purposes of concentrating their magnetic flux to the desired area of the motor. Although steel is normally not a good choice due to its electrical and magnetic properties, when sandwiched between two permanent magnets or employed outside of the directly applied magnetic field of the electromagnets, it will somewhat resist the losses normally present when solid steel is subjected to rapidly changing magnetic fields. In this respect the steel used under these conditions behaves to in a similar manner to the steel casing in ordinary DC electric motors. It becomes part of the magnetic circuit, however being somewhat shielded from changing magnetic fields, does not appreciably add either to inductive or hysteresis loss. For example, a hub drive system for one or more wheels in an electric vehicle can be easily employed using a steel wheel rim having permanent magnets mounted against the inside portion. The permanent magnets are placed next to each other on the inside of this rim having opposite polarity. The steel in the rim then magnetically connects these permanent magnets in series. A star shaped electromagnet is mounted in the center and bolted onto the vehicle frame. The rim portion of such a wheel is mounted to the hub portion using large structurally strong air moving spokes which provide air cooling by pumping air over the electromagnet assembly while the vehicle is in motion. This hub drive system has no gears, and therefore attaining high torque values becomes critical. In achieving this end, utilizing electromagnet windings which are capable of demagnetizing the rotor permanent magnets at stall and interlocking may be of benefit. This particular open motor design provides cooling, however such open motor designs must be made somewhat resistant to the elements. 
     As mentioned earlier depending on motor geometry, it may be desirable to move air by employing a turbofan as the central portion of the planar rotor. This works well when the star shaped electromagnet geometry is used in the center of the motor with the rotor permanent magnets rotating around the periphery of the centrally located stationary electromagnets. It is desirable that such a turbofan is capable of moving large volumes of air over the electromagnets while running at relatively low RPM values. An example of such a turbofan is outlined in U.S. Pat. No. 5,075,606 by Leonard H. Lipman in which the author uses this turbofan design to move large volumes of air at low RPM values by maximizing the available cross section. The impeller portions of such a turbofan are ideal for cooling the large-diameter DC permanent magnet motor of this invention having the above described geometry. 
     In view of the foregoing, it is an object of this invention to provide methods and apparatus for increasing power of permanent magnet motors. 
     SUMMARY OF THE INVENTION 
     In summary, the present invention provides a method for increasing the power output of permanent magnet motors. A power supply capable of demagnetizing motor permanent magnets is power limited to a safe level sufficient to prevent demagnetization on motor start up. Speed and/or current sensing circuitry activates full power to the motor when conditions such as speed and current reach a level sufficient to prevent demagnetization. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the magnetic flux paths in the stator assembly of a brush timed permanent magnet DC electric motor. 
     FIG. 2 shows the magnetic flux path of one of the stator electromagnet assemblies of this invention. 
     FIG. 3 shows a detailed drawing of the stator portion of the motor of this invention. 
     FIG. 4 shows the rotary disc portion of the motor of this invention with built in impeller. 
     FIG. 5 shows a diagram of circuitry needed to drive the high-powered DC turbofan cooled motor of this invention. 
     FIG. 6 shows a stator electromagnet having multiple windings of differing wire diameter for increasing motor torque at high RPM values. 
     FIG. 7 shows an overall diagram of the high-powered DC turbofan cooled motor of this invention. 
     FIG. 8 shows an overall diagram of the high-powered DC turbofan cooled motor of this invention having two rotor discs mounted onto the same central shaft. 
     FIG. 9 shows a diagram of the armature of the motor of this invention having short flexible blades emanating radially from the edge of the rotor which allows for adequate cooling under low RPM values but which limits air flow under high RPM values to prevent excess power consumption. 
     FIG. 10 shows a current sensing device which prevents accidental demagnetization of the rotor permanent magnets at low speeds. 
     FIG. 11 shows the rotary portion of the motor of this invention having a toothed edge for engagement to a gear or cog belt. 
     FIG. 12 shows the rotary portion of the motor of this invention consisting of a disc having a smooth surface. 
     FIG. 13 shows the rotary portion of the motor of this invention consisting of a disc having a roughened surface to increase airflow. 
     FIG. 14 shows the top view of an optical encoder disc along with photocell gates to provide timing for the high power motor of this invention. 
     FIG. 15 shows a tilted view of an optical encoder disc and photocell gate used to provide timing for the high power motor of this invention. 
     FIG. 16 shows a side view of the high power motor of this invention including a small generator on the shaft for speed sensing, speed sensing circuitry, optical timing circuitry, and amplification circuitry. 
     FIG. 17 is a schematic diagram showing optical timing circuitry integrated with transistor amplification circuitry which provides power to the electromagnets in the motor of this invention. 
     FIG. 18 shows an electromagnet assembly including switching circuitry having thick wire wrapped around the core to a first tap, and thinner wire wrapped over the thick wire to a second tap. 
     FIG. 19 shows a sectional view of the edge of the disc traveling through an electromagnet gap including permanent magnets sandwiching a flat steel spoke. 
     FIG. 20 shows a multitap electromagnet having the tap selection controlled by a relay which receives a voltage signal from a small electric generator. 
     FIG. 21 shows a smooth rotary disc rotor of this invention incorporating a non-magnetizable high permeability material in the periphery to provide mechanical power by switch-reluctance. 
     FIG. 22 shows a rotary disc rotor having a rough texture surface incorporating a non-magnetizable high permeability material in the periphery to provide mechanical power by switch-reluctance. 
     FIG. 23 shows the rotary portion of a brush timed permanent magnet motor having two separate electromagnet windings wrapped around the core each having their own set of commutators, and a centrifugal switch. 
     FIG. 24 shows the rotary portion of a brush timed permanent magnet motor having added windings which are made from thicker wire than the first set along with a centrifugal switch. 
     FIG. 25 shows a brush timed permanent magnet electric motor employing a rotor having two separate electromagnet windings, and a centrifugal switch for activating both sets of windings at a pre-set value. 
     FIG. 26 shows a brush timed permanent magnet DC electric motor having added u winding, which are made from thicker wire than the first set. 
     FIG. 27 shows the stationary electromagnet portion of a typical brushless permanent magnet DC electric motor having added electromagnet windings which are made from thicker wire than the first set. 
     FIG. 28 shows the stationary electromagnet portion of a typical brushless permanent magnet DC electric motor having electromagnet windings made from twisting two strands of electromagnet wire together. 
     FIG. 29 shows the stationary electromagnet portion of a typical brushless permanent magnet DC electric motor employing two sets of electromagnet windings which are electrically isolated from each other. 
     FIG. 30 shows the permanent magnet rotary portion of a typical brushless DC electric motor. 
     FIG. 31 shows a typical DC brushless electric motor employing added electromagnet windings which are made from thicker wire than the first set along with an interlock mechanism. 
     FIG. 32 shows the rotary portion of a large diameter brushless DC electric motor consisting of a central turbofan portion and permanent magnets around the periphery. 
     FIG. 33 shows a large diameter brushless DC electric motor having a rotary portion consisting of a central turbofan and permanent magnets around the periphery, and a centrally located star shaped electromagnet. 
     FIG. 34 shows a large diameter brushless DC electric motor having a rotary portion consisting of a central turbofan and permanent magnets around the periphery, a centrally located star shaped electromagnet, and added gear teeth around the outside periphery. 
     FIG. 35 shows a large diameter brushless DC electric motor having a rotary portion consisting of a central turbofan and permanent magnets around the periphery, a centrally located star shaped electromagnet, and teeth for engagement to a cog belt around the outside periphery. 
     FIG. 36 shows a large diameter air cooled electric motor of this invention employed in a vehicle hub drive system having a steel rim, permanent magnets attached to the inside portion, a star shed electromagnet assembly which is bolted onto the vehicle frame, and large structural air moving spokes for connecting the outer rim portion to an axle assembly. 
     FIG. 37 shows the rotary portion of a large diameter brushless DC motor consisting of a planar disc having permanent magnets about the periphery in a radial direction, and fixed air moving vanes protruding from the edge. 
     FIG. 38 shows a large diameter brushless motor consisting of a planar disc rotor having permanent magnets about the periphery in a radial direction, electromagnets pointing inward toward the edge of the disc, and fixed air moving vanes protruding from the edge of the disc which move air over the electromagnets. 
     FIG. 39 shows the rotary portion of a large diameter brushless DC electric motor consisting of a central turbofan portion and non-magnetizable high permeability material around the periphery. 
     FIG. 40 shows the rotary portion of large diameter brushless DC electric motor consisting of a planar disc having non-magnetizable high permeability material embedded on the outside periphery, along with added air moving surfaces. 
     FIG. 41 shows the rotary portion of a traditional brush timed permanent magnet motor employing a single set of electromagnet windings. 
     FIG. 42 shows a traditional brush timed permanent magnet motor having a single set of electromagnet windings along with current sensing and interlocking circuitry. 
     FIG.43 shows a brushless permanent magnet motor employing current sensing and interlocking circuitry. 
     FIG. 44 shows a side view of a high power disc motor of this invention including a small generator on the shaft for speed sensing, speed sensing circuitry, optical timing circuitry, amplification circuitry, and current limiting circuitry. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 shows the open magnetic circuit in the stator portion of a traditional permanent magnet DC motor. Encased in thick steel housing  2  are permanent magnets  4  and  6  having opposite poles  8  and  10  against housing  2 . Also shown are permanent magnet poles  12  and  14  which are aligned with each other across air gap  16 . Also shown are lines of magnetic flux  18  which travel both through the motor housing  2  as well as through air gap  16 . Thus, the completion of flux lines  18  from permanent magnets  4  and  6  requires a thick magnetic motor housing  2  as part of the magnetic circuit. 
     FIG. 2 shows the flux path produced by stator electromagnet  20  in the electric motor of this invention. Stator electromagnet  20  consists of a magnetic core  22  in the shape of a “C” which is wound with electromagnet wire  24 . When electromagnet windings  24  are energized, magnetic flux  26  is generated in accordance with the right-hand rule of electrically induced magnetism. The magnetic flux  26  that is generated is contained within core  22  and emerges from pole faces  28  and  30 . With the electromagnet geometry shown in FIG. 2, the magnet flux generated remains entirely within air gap  32  of the electromagnet  20 . The electromagnet geometry of this invention is based on a Rowland ring. A Rowland ring was named after J. H. Rowland who made use of it in his experimental work on electricity and magnetism. A Rowland ring consists of a torroidal coil of wire wrapped around an iron core. The unique property of a Rowland ring is that the magnetic flux generated is confirmed wholly to the core. The electromagnet design shown in FIG. 2 is a Rowland ring which has been modified into an electromagnet by removing a section to produce an air gap having opposite magnet poles on each side. 
     FIG. 3 shows the stator portion  34  of the high powered air cooled DC motor of this invention. Several electromagnets  20  are mechanically fastened to end plates  36  and  38 . Also shown is an opening  40  in end plate  36  which allows air to flow through the motor for the purposes of cooling. Also shown is a bearing  42  for the purposes of providing a mechanical surface for supporting the rotatable motor shaft of the rotor portion. 
     FIG. 4 shows the rotary disc portion of the motor of this invention  44  which consists of an outer portion  46  and an inner turbofan portion  48 . Inner turbofan portion  48  consists of individual blades  50  connecting a central axle  52  to edge portion  46 . Edge portion  46  has several permanent magnets  54  mounted having their magnetic pole faces  56  and  58  on opposite sides  60  and  62  of outer disc portion  46 . 
     FIG. 5 shows a circuit diagram for properly timing and supplying power to the stator electromagnets of this invention in order to drive the rotor. The circuit serves to initially energize the coil of electromagnet  20  in one direction to pull an adjacent permanent magnet into the field of the electromagnet, and then reverses the energization applied to coil  24  to push the permanent magnet out of the electromagnet  20  and to pull the next permanent magnet forward. When permanent magnet  54  passes the Hall effect sensor  76 , power from battery  66  flows through resistors  78  and  80  and Zener diode  82  to activate opto-isolator  84 . The phototransistor portion of opto-isolator  84  is wired to the gate portion of MOSFET power transistor  70  through biasing resistor  86 . Biasing resistor  86  in turn is connected to the positive side of battery  67 . Alto Resistor  88  connects the gate of MOSFET power transistor  70  to the negative side of battery  66  and serves two purposes. One purpose is to discharge the gate capacitance of transistor  70  for rapid turn off; and the other purpose is to divide the battery voltage to the gate to allow for low gate turn-on voltages with relatively high battery voltages. 
     Thus, when Hall effect sensor  76  is activated by permanent magnet  54 , transistor  70  is turned on with full power. Power from batteries  66  and  67  is then delivered to electromagnet  20  through diode  90 . Electromagnet  20  then moves the wheel forward by pulling permanent magnet  54  into its field. When permanent magnet  54  approaches its equilibrium position, Hall effect sensor  76  is shut off. The unused magnetic energy stored in the electromagnet shows up as a reverse EMF spike. Diode  90  isolates transistor  70  from this spike. Diode  92  then shunts this spike into batteries  67  and  68  to give them a slight charge. Permanent magnet  54  passes by Hall effect sensor  74 , switching power from battery  68  though resistors  94  and  96  and Zener diode  98  to activate opto-isolator  100 . The phototransistor portion of opto-isolator  100  is wired to the gate portion of MOSFET power transistor  72  through biasing resistor  102 . Biasing resistor  102  in turn is connected to the positive side of battery  69 . Resistor  104  connects the gate of MOSFET power transistor  72  to the negative side of battery  68  for the purposes of draining the gate capacitance of MOSFET power transistor  72  when the gate voltage is shut-off and divides the gate voltage used to maintain a safe operating level at the gate. Thus when Hall effect sensor  74  is activated by permanent magnet  54 , MOSFET power transistor  72  is turned on with fall power. Power from batteries  68  and  69  is then delivered to electromagnet  20  through diode  106 , in the opposite direction from that supplied through transistor  70 . Electromagnet  20  moves the rotor forward by pushing permanent magnet  54  out of its field, and pulling the next successive permanent magnet into the field. Once permanent magnet  54  has been sufficiently moved out of the field of electromagnet  20 , Hall effect sensor  74  shuts off power to the circuit. Stored magnetic energy left in electromagnet  20  shows up as a back EMF spike which is isolated from MOSFET power transistor  72  by diode  106  and is shunted across diode  108  into batteries  66  and  67 , thus completing the cycle. 
     FIG. 6 shows one of the stator electromagnets  20  of the high-powered turbofan cooled DC motor of this invention. Electromagnet  20  consists of a laminated iron core  22  in the shape of a “C” which is wrapped with a single layer of heavy gauge electromagnet wire  108  having Ado ends  100  and  112 . End  112  is then electrically connected to one end  114  of a lower gauge electromagnet wire  116  which is wound in a second layer over the heavy gauge wire to give a free exposed end  118 . 
     FIG. 7 shows a diagram of the complete motor of this invention. Rotor disc  44  along the central shaft  52  is surrounded by electromagnets  20  straddling the edge of disc  44  in alignment with permanent magnets  54  in the rotary disc portion. Further employed are bearings  42  in end plates  36  and  38 . End plates  36  and  38  together with electromagnets  20  provide the stationary part of this motor. Hall effect sensors  74  and  76  provide the timing for amplification circuitry  108  and is distributed to electromagnets  20  by wires  110 . 
     FIG. 8 shows two discs  44  on a single shaft  52 . Each disc is driven by its own set of electromagnets  20 . This geometry provides high torque in a package having a limited diameter and also results in an overall reduction in inertia mass. 
     FIG. 9 shows a rotor disc  44  having permanent magnets  54  mounted in the same configuration as those shown in FIG.  4 . The disc of FIG. 9 does however have a solid center and fan blades  112  along the edge to provide direct cooling to the electromagnets (now shown). Fan blades  112  may be made of a flexible material such as mylar, kapton, or other polymer film. The flexible fan blades allow for high air flow at low RPM values and reduce aerodynamic drag at high RPM values. 
     FIG. 10 shows an example of current limiting circuitry suitable for preventing accidental demagnetization of rotor permanent magnets  54  (not shown). A small laminated iron core  112  having slot  116  is provided with several turns of heavy gauge wire  114 . Magnetic poles  118  and  120  are formed when current flows through wire  114 . Into slot  116  is placed a Hall effect sensor  122  having Schmidt Triggering Circuitry which is used to sense the magnetic field present within gap  116 . Windings  114  on iron core  112  are wired in series with electromagnet  20  (not shown). When an unacceptable amount of current flows through windings  114 , the magnetic field generated in small iron core  112  activates Hall effect sensor  122  which grounds out the gate of the corresponding MOSFET power transistor providing power to electromagnet  20  and momentarily cuts off the current. The Schmidt triggering aspect of Hall effect sensor  122  is no advantageous in switching the power transistors on and off rapidly in place of reducing the constant current flow on a continuous basis. Such switching results in virtually no voltage drop across circuit elements and allows the MOSFET drive transistors to run cool even under current limiting conditions. 
     This current limiting device can be used to control current in motor windings to a level sufficient to prevent demagnetization. A single power supply capable of demagnetizing motor permanent magnets under stall conditions may be used with permanent magnet motors having only one winding configuration. The use of this device in conjunction with speed sensing circuitry provides additional protection against accidental demagnetization. 
     In FIG. 11, rotary disc  124  consists of an outer disc portion  126  fixedly mounted to a central shaft  52  by turbofan blades  50 . Outer disc portion  126  has permanent magnets  54  fixedly mounted into outer disc portion  126  with their direction of magnetization transversing through the disc. Also shown are high and low areas  128  and  130  cut into the periphery of outer disc portion  126 . These high and low areas may be in the form of gear-type teeth or other teeth suitable for engaging a cog-type belt or other suitable mechanical drive mechanism capable of engaging the outer edge of outer disc portion  126 . It should be noted that in some instances several electromagnets (not shown) may have to be removed to allow for mechanical coupling from the edge. 
     FIG. 12 shows a large diameter disc-shaped rotor  132  having smooth top and bottom surfaces  134  and  136  respectively. Also shown are permanent magnets  54  in edge portion  46  of rotor  132 . Permanent magnets  54  are mounted having their magnetic pole faces  56  and  58  on opposite sides  60  and  62  of outer disc portion  46 . Also shown is shaft  52 . 
     FIG. 13 shows a large diameter disc-shaped rotor  138  having rough textured top and bottom surfaces  140  and  142 . Located in the periphery of disc  138  are several permanent magnets  54  mounted having their magnetic pole faces  56  and  58  on opposite sides  140  and  142  of disc  138 . As usual shaft  52  is used for power output and registration within the motor. 
     FIG. 14 shows the top view of an optical encoder disc  144  having a central portion  146  and an edge portion  148 . Edge portion  148  consists of alternating opaque areas  150  and transparent areas  152 . Also shown are two photocell gates  154  and  156  used to provide a signal for timing purposes. 
     FIG. 15 shows a tilted view of optical encoder disc  144  and photocell gate  154 . Also shown is shaft  158  which is directly fastened to the end of the motor shaft (not shown). 
     FIG. 16 shows a side view of the disc rotor air cooled motor of this invention. Disc rotor motor  160  is shown in complete form. This particular motor includes a small electric generator  162  which senses the rotor speed by generating a voltage which is proportional to the speed. Generator  162  is of the permanent magnet type and therefore requires no field windings and therefore no input power. Such a generator can be either of the DC output type, or conversely the AC output type. In the case of permanent magnet DC output generators, a simple permanent magnet motor will often suffice. Although many speed sensing methods may be employed, the generator offers the best protection against failed circuit components. Such failure can cause premature shunting of electromagnet windings resulting in the potential for demagnetization of rotor permanent magnets. The generator absolutely will not put out a given voltage until a minimum RPM value has been achieved. Failure of the generator results in low or no output voltage. This failure mode will not result in premature shunting problems. Generator  162  can be wired to a relay to either automatically shunt electromagnet taps at a particular speed, or interlock out the accidental premature shunting of electromagnet taps. Generator  162  of motor  160  is wired to a control box  164 . Control box  164  contains interlocking circuitry. Beneath generator  162  of motor  160  is optical encoder  166 . Optical encoder  166  is mounted to motor shaft  152 . The optical encoder itself is shown in detail in FIGS. 14 and 15 previously described. Optical encoder  166  is wired to amplification circuitry  168  which amplifies the signal from optical encoder  166  and inputs the amplified signal into electromagnets  20 . 
     Supported on motor shaft  52  is rotary disc  170  having portions of high permeability magnetic material  172  transversing through the edge portion of disc  170 . FIG. 16 particularly illustrates the plurality of C-shaped electromagnets  20  configured to define an inner annular channel  173 . The annular edge portion of disc  170  is rotatably disposed within in annular his channel  173 . In the case of a permanent magnet motor design, high permeability magnetic material  172  consists of permanent magnets. In the case of a switched reluctance motor design, non-magnetizable ferrite, laminated silicon steel, or powdered iron composite may be employed. Also shown are flexible plastic fan blades  112  which provide air currents to cool electromagnets  20 . Motor end plates  36  and  38  provide support for motor shaft  52 , electromagnets  20 , and Who motor bearings  42 . The permanent magnets are disposed on the annular edge portion of disc  170  so that the directions of magnetization thereof transverse through disc  170 . In addition, the poles of the permanent magnets are aligned in coupling proximity to the poles of the electromagnets of the stator. 
     FIG. 17 shows optical timing circuitry integrated with transistor amplification circuitry which provides power to the electromagnets in the motor of this invention. Optical timing gate  154  consists of a light emitting diode  174  and a phototransistor  176  separated by a gap through which the optical timing disc passes (not shown) such optical gates are commercially available from Omron Electronics, Inc., located at One East Commerce Drive Schaumburg, Ill. 60173. Part No. EESG3 is a suitable optical timing gate, although many others will work as well. The motor timing should be 40% on time from sensor  154 , then 10% off time, then 40% on time from sensor  156 , then 10% off time to complete the cycle. The motor timing itself will vary with the desired operating parameters, but in general the electromagnets should be turned on slightly early with respect to rotor position. 
     Optical timing gate  154  has its output transistor portion  176  wired to the gate portion of MOSFET power transistor  70 . The choice of the exact MOSFET power transistor will depend on the requirements of the particular motor. International Rectifier located at 233 Kansas Street., El Segundo, Calif. 90245 makes a variety of Hexfet MOSFET power transistors. One should be chosen with a low on resistance, and a rated operating voltage of at least twice the voltage used in the motor. The current rating capacity should be several times the normal running current through the device. For example, for an operating voltage of 24 volts, IRFZ48 would be a good choice. This particular transistor has an on resistance of 0.018 ohms, a source to drain voltage of 60 volts, and a continuous current rating of 72 amperes. Proper heat sinking is also recommended. Resistors  86  and  88  provide voltage dividing to the gate of MOSFET power transistor  70 . These values should be chosen to properly divide the gate voltage, allow for quick turn on and turn off, and not drain excessive battery power. In general they should be chosen to provide 1 milliampere of switching current. Resistor  88  also drains the gate capacitance of MOSFET power transistor  70  when the gate voltage is shut off by optical sensor  154 . This allows for clean switching. 
     When mechanical switch  64  is closed, electromagnet  20  is controlled by MOSFET switching transistors  70  and  72 . Light emitting diode  174  is on continuously from voltage supplied from battery  66  and is controlled by Zener diode  82  and resistor  80 . When a transparent portion of the optical timing disc (not shown) passes by optical timing gate  154 , LED portion  174  transmits its light to photo transistor  176 . Phototransistor  176  turns on and power flows through voltage dividing resistors  86  and  88 . This turns on MOSFET power transistor  70  thereby providing power from batteries  66  and  67  through diode  90  and into electromagnet  20 . The interaction of the magnetic field produced by electromagnet  20  and the magnetic material in the rotor provides propulsive force to the edge of the rotor thereby providing mechanical power. Just before the magnetic material in the rotor(not shown) aligns itself in the magnetic field in the electromagnet, optical sensing gate  154  is shut off by an opaque region of the optical timing disc (not shown). MOSFET power transistor  70  is then shut off. Remaining stored magnetic energy in electromagnet  20  then shows up as a reverse voltage spike. Diode  90  isolates MOSFET power transistor  70  from this spike while diode  92  shunts this reverse voltage spike into batteries  68  and  69  giving them a slight charge. As the magnetic material in the rotor passes by its equilibrium position with respect to electromagnet  20 , optical sensing gate  156  is turned on as a transparent portion of the optical timing disc (not shown) passes through. Light emitting diode  178  is on continuously from voltage supplied from battery  68  and is controlled by Zener diode  98  and resistor  96 . Light from light emitting diode  178  in optical sensing gate then activates phototransistor  180  thereby supplying voltage to the gate of MOSFET power transistor  72  through voltage dividing resistors  102  and  104 . MOSFET power transistor  72  then turns on supplying power from batteries  68  and  69  to electromagnet  20  through diode  106 . The interaction of the magnetic field provided by electromagnet  20  and the magnetic material in the rotor provides further propulsive force to the edge of the rotor thereby providing mechanical power. Just before the magnetic material in the rotor (not shown) aligns itself in the magnetic field in the electromagnet, Optical sensing gate  156  is shut off by an opaque region of the optical timing disc (not shown). MOSFET power transistor  72  is then shut off. Remaining stored energy in electromagnet  20  then shows up as a reverse voltage spike. Diode  106  isolates MOSFET power transistor  72  from this spike while diode  108  shunts this reverse voltage spike into batteries  67  and  68  thus completing the cycle. 
     The timing of actual switching is fundamentally different between a disc rotor having permanent magnets and that of a disc rotor having non-magnetizable high permeability material. In the first case, permanent magnets can be made to repel as well as attract simply by changing the direction of current flowing through electromagnet  20 . In the second case of switched-reluctance, attraction is the only net force. The two transistor circuitry however is advantageous in driving such switched-reluctance motor designs in that utilization of reverse voltage spikes is easily achieved which also reduces arcing of switch contacts. 
     FIG. 18 shows an electromagnet assembly  20  with an SPDT switch  182 . Also shown is a common wire  184  and two tapped input leads  186  and  188 . Lead  188  is thick wire wound around the electromagnet core. Output lead  186  is the tap corresponding to the second layer of wire to be wrapped around the electromagnet core and is of a thinner gauge than that of the first layer of wire. The output lead from SPDT switch  182  is  190 . Thus output leads  184  and  190  of electromagnet  20  form a multiple tap electromagnet in conjunction with SPDT switch  182 . On motor start up SPDT switch  182  connects lead  190  to electromagnet lead  186 . The entire length of electromagnet wire is activated. The thin outer layer of wire connected to lead  186  prevents excessive electromagnet currents from demagnetizing permanent magnet  54 . Once a safe rotor speed has been achieved, SPDT switch  182  can be switched to electromagnet tap  188  thus shunting the entire length of thin electromagnet wire  186 . This will substantially increase rotor power, speed, and torque. 
     FIG. 19 shows a permanent magnet pair formed of permanent magnets  54  and  55  sandwiching a piece of steel  192 . Steel piece  192  forms a flat planar spoke to provide a strong mechanical bond between the inner portion of the rotor and the periphery where the permanent magnets are located. Also shown is a piece of non-magnetic material  194  which provides support for permanent magnets  54  and  55  during running. Non-magnetic material  194  also provides separation distance from T-shaped steel piece  196  thus preventing a short circuit of their magnetic flux. 
     FIG. 20 shows multiple tap electromagnet  20  interfaced to relay  198  for either interlocking of or automatic switching of electromagnet taps  182  and  186  based on a voltage input from a generator (not shown) to relay coil  200 . Variable resistors  202  and  204  control the activation voltage of relay  198 . 
     FIG. 21 shows a large diameter disc-shaped rotor  208  having smooth top and bottom surfaces  134  and  136  respectively. Also shown are sections of high permeability non-magnetizable ferromagnetic material  206  in edge portion  46  of rotor  208 . Also shown is shaft  52 . 
     FIG. 22 shows a large diameter disc-shaped rotor  210  having rough textured top and bottom surfaces  140  and  142 . Located in the periphery of disc  210  are sections of high permeability non-magnetizable ferromagnetic material  206 . As usual shaft  52  is used for power output and registration within the motor. 
     FIG. 23 shows the rotary portion of a brush timed permanent magnet motor having two separate sets of electromagnet windings  300  and  302 . Inner winding set  302  which is closest to shaft  322 , is always connected to commutator  304  regardless of speed. Because of this, when power is provided to commutator  304 , electromagnet windings  302  will be activated and the motor will run at low power. Once rotor RPM values reach a safe level that allow for winding set  300  to be activated without the risk of demagnetizing motor permanent magnets (not shown), centrifugal switch  306  closes thereby connecting outer windings  300  to commutator  308 . At this point, if more motor power is desired, power may be applied to commutator  308  thereby increasing the magnetic field of rotor electromagnet pole faces  310  and  312 . Holes  314 ,  316 ,  318 , and  320  in motor shaft  322  are used for routing the leads of electromagnet windings  302  under commutator  308  for connection to commutator  304 . 
     FIG. 24 shows the rotary portion of a brush timed permanent magnet electric motor having two layers of electromagnet windings  300 , and  301 . Layer  300  is the first layer which is made of wire having a heavier gauge than layer  301  which is the second layer. Also shown is commutator  308  which is wired to the start of winding  300  at connection  324 . The other end of winding  300  is connected to one side of centrifugal switch  306  and the start of winding  301  at connection  326 . The other connection  328  to centrifugal switch  306  is connected to commutator  308  and the remaining end of electromagnet winding  301 . Also shown is shaft  322 . When power is applied to commutator  308  by brushes (not shown) current to electromagnet winding  300  is limited by high resistance electromagnet winding  301 . Under these conditions, permanent magnet motors employing such rotors will run at low power. Once rotor RPM values reach a safe level whereby shunting of electromagnet windings  301  will not result in demagnetization of motor permanent magnets (not shown), centrifugal switch  306  closes connection  326  to connection  328  thereby shunting electromagnet winding  301 . This allows electromagnet winding  300  to be activated with fill power. This increases the magnetic field of rotor electromagnet pole faces  310  and  312 . 
     FIG. 25 shows a brush timed permanent magnet electric motor  330  employing the rotor of FIG.  23 . Shaft  322  of this motor is rotatably supported by motor bearings  332  and  334  in end caps  336  and  338 . End caps  336  and  338  are mounted to motor casing  340  and support bearings  332  and  334 . Also shown are brushes  342 ,  344 ,  346 , and  348 , which are supported by brush mounts  358  and  360 . Brushes  342 ,  344 ,  346 , and  348  provide electric power to rotor commutators  304 , and  308 . Motor leads  350 ,  352 ,  354 , and  356  are electrically connected to brushes  342 ,  344 ,  346 , and  348 , and are used for supplying electric power to motor  330 . Centrifugal switch  306  is also shown which allows commutator  308  to supply power to extra electromagnet winding  300  at a pre set RPM value. Also shown is a cut away portion of electric motor  330  showing one of the motor permanent magnets  359  which is mounted against motor casing  340 . Also shown in the cut away portion of this drawing is rotor electromagnet pole face  312 . 
     FIG. 26 shows a brush timed permanent magnet electric motor  362  employing the rotor of FIG.  24 . Shaft  322  of this motor is rotatably supported by motor bearings  332  and  334  in end caps  336  and  338 . End caps  336  and  338  are mounted to motor casing  340  and support bearings  332  and  334 . Also shown are brushes  342 , and  346 , which are supported by brush mounts  358  and  360 . Brushes  342  and  346  provide electric power to rotor commutator  304 . Centrifugal switch  306  is also shown which shunts out the thinner outer electromagnet windings (not shown) in the rotational portion of motor  362  when the RPM value reaches a pre set level. Also shown is a cut away portion of electric motor  362  showing one of the permanent magnets  358  which is mounted against motor casing  340 . Also shown in the cut away portion of this drawing is rotor electromagnet pole face  312 . 
     FIG. 27 shows the stationary electromagnet portion  364  of a typical brushless permanent magnet DC electric motor having added electromagnet windings which are made from thicker wire than the first set. Electromagnet casing  340  is made from steel and therefore is capable of efficiently transmitting magnetic flux. Stator electromagnets  366  and  368  consist of laminated electrical steel to reduce eddy current losses when the motor is in operation. Stator electromagnet  366  has two pole faces  370  and  372 . Pole face  370  is attached to motor casing  340 . Electromagnet pole face  372  faces inward in a radial direction and is aligned with the opposing inward facing electromagnet pole face  374  of electromagnet  368 . Electromagnet  368  has a second pole face  376  which is attached to motor casing  340 . Both electromagnets  366 , and  368  are wrapped with two layers  378 , and  380 , of electromagnet wire. The first layer of electromagnet wire, layer  378 , is of a greater thickness in cross section than is the wire of second layer  380 . Layers  378  and  380  are both wired in series with a central tap  382  which is common to both windings. Wire lead  384  is the starting lead made of thick wire for electromagnet windings  378  and  380 . This lead is the starting lead. Lead  382  is the lead at the end of thick electromagnet winding  378 . This lead is also the starting of thinner electromagnet winding  380 . Lead  386  represents the end lead of thinner electromagnet winding  380 . When power is applied to leads  384 , and  386 . Because the thinner electromagnet wire is in series with the thicker wire, the current to the motor is limited to that which will flow under the applied voltage through the resistance of both windings in series. When power is applied across leads  382  and  384 , a significantly greater amount of current flows thus increasing the magnetic field between stator electromagnet pole faces  372 , and  374 . 
     FIG. 28 shows the stationary electromagnet portion  388  of a typical brushless permanent magnet DC electric motor employing electromagnet windings which are made from twisting two strands of electromagnet wire together prior to winding of stator electromagnets  390  and  392 . Electromagnet casing  340  is made from steel and therefore is capable of efficiently transmitting magnetic flux. Stator electromagnets  390  and  392  consist of laminated electrical steel to reduce eddy current losses when the motor is in operation. Stator electromagnet  390  has two pole faces  394  and  396 . Pole face  394  is attached to motor casing  340 . Electromagnet pole face  396  faces inward in a radial direction and is aligned with the opposing inward facing electromagnet pole face  398  of electromagnet  392 . Electromagnet  392  has a second pole face  400  which is attached its to motor casing  340 . Both electromagnets  390 , and  392  are wrapped with two twisted strands  402 , and  404 , of electromagnet wire. Electromagnet wire strands  402 , and  404 , are electrically connected to each other at lead  406 . The two twisted strands of wire are then wound around both electromagnet cores thus forming electromagnets  390 , and  392 . The two ends  408 , and  410  of the twisted strand are kept electrically isolated from one another. When electric power is applied as across lead  406  and either lead  408  or lead  410 , the current to the motor is limited to that which will flow under the applied voltage through the resistance of a single strand of wire. When leads  408  and  410  are electrically connected together, both strands of wire are now connected in parallel. The amount of current that will flow through the electromagnet windings is effectively doubled. Under these conditions, an increase in the magnetic field between stator electromagnet pole faces  396 , and  398  is the result. 
     FIG. 29 shows the stationary electromagnet portion  432  of a typical brushless DC permanent magnet electric motor employing two isolated sets of electromagnet windings on stator electromagnets  420  and  422 . Electromagnet casing  340  is made of steel and therefore is capable of efficiently transmitting magnetic flux. Stator electromagnets  420  and  422  consist of laminated electrical steel to reduce eddy current losses when the motor is in operation. Stator electromagnet  420  has two pole faces  424 , and  426 . Pole face  426  is attached to motor casing  340 . Electromagnet pole face  424  faces inward in a radial direction and is aligned with the opposing inward facing electromagnet pole face  428  of electromagnet  422 . Electromagnet  422  has a second pole face  430  which is attached to motor casing  340 . Both electromagnets are wound with two separate sets of windings. Electromagnet  420  is wound with a first set of windings  434 , and a second set of windings  436 . Electromagnet  422  is wound with a first set of electromagnet windings  438 , and a second set  440 . Electromagnet windings  434 , and  438  are connected together in series and end at leads  412 , and  414 . Electromagnet windings  436 , and  440  are connected together in series and end at leads  416 , and  418 . Applying electric power to either set of leads results in a magnetic field in electromagnets  420 , and  422  that will not be sufficient to demagnetize rotor permanent magnets (not shown) under motor stall conditions. When it is desirable to increase the field strength of electromagnets  420 , and  422  power is appropriately applied to both sets of leads. 
     FIG. 30 shows the rotary portion of a typical DC brushless electric motor. Rotary portion  442  consists of a shaft  322  attached to permanent magnets  444 , and  446 . Permanent magnets  444 , and  446  have their direction of magnetization such that exposed face  448  of permanent magnet  446  is north and points outward in a radial direction, and exposed face  450  of permanent magnet  444  is south and points outward in a radial direction as well. 
     FIG. 31 shows a brushless DC electric motor of this invention having the front end cap removed to expose the inner workings. Rotor  442  of FIG. 30 is shown inside of multi-tap electromagnet assembly  364  of FIG.  27 . Also shown is end cap  338  and small electric generator  452 . Small electric generator puts out a voltage which is proportional to motor RPM values and is used as part of the interlocking circuitry of this invention. Power output leads  554 , and  556  of small electric generator  452  are wired to a relay such as relay  200  of FIG. 20 in the original application. Also shown is the photocell gate casing  558  which houses the photocell gate circuitry for sensing rotor position. A detailed diagram of the photocell gate and light control disc are shown in FIG. 15 of the original application. Photocell gate sensor leads  560 ,  562 ,  564 , and  568  are wired to the transistor amplification circuitry shown in FIG. 17 of the original application. Also wired to this circuitry of course are motor power input leads  382 ,  384 , and  386 . 
     FIG. 32 shows the rotary portion  570 , of a large diameter brushless DC electric motor consisting of a central turbofan portion  572 , and permanent magnets  574  around the inside periphery of rotary portion  570 . Also shown is motor shaft  576  which is fixedly mounted to the center of turbofan portion  572 . Permanent magnets  574  are mounted having their pole faces facing inward in a radial direction, and oppositely polarized with each successive permanent magnet. The opposite pole faces of each permanent magnet are facing the inner portion  578  of the periphery portion of rotor  570 . The periphery portion of rotor  570  is made from a ferromagnetic material such as steel to magnetically connect permanent magnets  574  and concentrate their flux inward in a radial direction. 
     FIG. 33 shows a large diameter brushless DC electric motor  592 , consisting of the rotary portion of FIG. 32, and a centrally located star shaped electromagnet  580 . Bearing  588  rotatably connects end plate  586  to motor shaft. End plate  586  is fixedly mounted into the central portion of star shaped electromagnet  580 . Mounting holes  590  are used to mount the motor to a suitable piece of equipment such as the frame of an automobile, or some piece of high powered industrial equipment. Power input leads  582  and  584  provide power to star shaped electromagnet  580  through a transistor amplification circuit (not shown) such as the one illustrated in FIG. 17 in the original patent application. The motor is timed with position sensing circuitry (not shown) such as the photocell gate assembly outlined in FIG. 15 in the original patent application. 
     FIG. 34 shows a large diameter brushless DC electric motor  592  having a rotary portion consisting of a central turbofan and permanent magnets around the periphery, a centrally located star shaped electromagnet, and added gear teeth  594  around the outside periphery. 
     FIG. 35 shows a large diameter brushless DC electric motor  592  having a rotary portion consisting of a central turbofan and permanent magnets around the periphery, a centrally located star shaped electromagnet, and teeth  596  for engagement to a cog belt around the outside periphery. 
     FIG. 36 shows a large diameter air cooled electric motor  592  of this invention employed in a vehicle hub drive system having a steel rim  598 , permanent magnets attached to the inside portion, a star shaped electromagnet assembly  580 , which is bolted onto the vehicle frame (not shown), and large structural air moving spokes  600  for connecting the outer rim portion  598  to axle assembly  576 . 
     FIG. 37 shows the rotary portion  602  of a large diameter brushless DC motor consisting of a planar disc  604  having permanent magnets  606  about the periphery in a radial direction, and fixed air moving vanes  608  protruding from the edge. In this particular large diameter rotor, permanent magnets  606  have a direction of magnetization which is in a radial direction with each successive permanent magnet being oppositely polarized. Fixed air moving vanes  608  are on the top surface of planar disc  604  and move air from top to bottom of the electromagnets (not shown). 
     FIG. 38 shows a large diameter brushless motor  610  consisting of a planar disc rotor  602  having permanent magnets  606  about the periphery in a radial direction, electromagnets  614  pointing inward toward the edge of the disc, and fixed air moving vanes  608  protruding from the edge of the disc which move air over electromagnets  614 . Also included is electromagnet mounting plate  616  along with bearings  618  and  620  which rotatably connect mounting brackets  622 , and  624  to motor shaft  626 . Mounting brackets  622 , and  624  are firmly fastened to mounting plate  616 . Electric power is applied to leads  628 , and  630  from the transistor amplification circuit of FIG. 17 in the original patent application (not shown). As usual, Timing is provided by the photo-optic position sensing apparatus of FIG. 15 in the original application (not shown). 
     At FIG. 39 shows the rotary portion  630  of a large diameter brushless DC electric motor consisting of a central turbofan portion  632 , motor shaft  634 , and non-magnetizable high permeability material  638  mounted to inside surface  636  in the periphery portion of rotary portion  630  as well as mounting hardware  686 ,  688 , and  690  of FIG.  33 . Also employed is electromagnet  580  which is shown in FIG.  33 . Electromagnet timing is carried out using the photocell gate shown in FIG. 15 of the original patent application. Amplification of the timing signal from the photocell gate is carried out using the electrical circuitry shown in FIG. 17 of the original patent application. 
     FIG. 40 shows the rotary portion  640  of a large diameter brushless DC electric motor consisting of a planar disc  642  having non-magnetizable high permeability material  644  embedded on the outside periphery, along with added air moving surfaces  608 . Also employed are electromagnet  614  of FIG. 38, as well as mounting hardware  616 ,  618 ,  620 ,  622 ,  624 , and  626  of FIG.  38 . As usual, electromagnet timing is carried out using the photocell gate shown in FIG. 15 of the original patent application. Amplification of the timing signal from the photocell gate is carried out using the electrical circuitry shown in FIG. 17 of the original patent application. 
     FIG. 41 shows the rotary portion of a traditional brushed timed permanent magnet motor. Rotary portion  646  consists of a single set of electromagnet windings  300  along with a commutator  308 . Both ends  303  and  305  of electromagnet winder  300  are wired to commutator  308 . Commutator  308  is segmented and provides electrical connection between brushes (not shown) and rotor electromagnet windings  300 . Also shown is shaft  322 . When power is applied to commutator  308 , brushes (not shown) provide current to electromagnet windings  300 . This produces the needed magnetic field at electromagnet pole faces  311  and  313 . 
     FIG. 42 shows a brush timed permanent magnet motor employing the power supply control aspects of this invention. Permanent magnet motor  650  is shown employing the rotor of FIG. 41 along with DC power supply  652  and current limiting circuitry  654  of FIG.  10 . Power supply  652  consists of power control MOSFET transistor  660  and DC power source  656 . DC power sources are well known I the art and include batteries, rectified transformers, switching power supplies, DC-DC converters, and other. DC power source  656  is of sufficient power to demagnetize permanent magnets  358  if allowed to deliver full power during motor start up. Power control MOSFET  660  is connected to current limiting circuitry  654 . Also shown is diode  662  which is reversed wired across the output power of power supply  652  to reduce back EMF effects from electric motor  650 . 
     Shaft  322  of this motor is rotatably supported by motor bearings  332  and  334  in end caps  336  and  338 . End caps  336  and  338  are mounted in motor casing  340  and support bearings  332  and  334 . Also shown are brushes  342  and  346 , which are supported by brush mounts  358  and  360 . Brushes  342  and  346  provide electric power to commutator  308 . Also shown is a cut away portion of electric motor  650  showing one of the permanent magnets  358  which is mounted against motor casing  340 . Also shown in the cut away portion of this drawing is rotor electromagnet pole face  313 . 
     DC power supply  652  provides enough current and voltage to demagnetize motor permanent magnets  358  if allowed to provide full power during motor start up. Current limiting circuitry  654  (shown in FIG. 10) limits peak currents delivered to motor windings  300  to a level sufficient to prevent demagnetization of permanent magnets  358 . At motor start up, power supply  652  provides enough power to electric motor  650  to demagnetize permanent magnets  358 . Motor electromagnet windings  300  initially produce a back EMF effect which initially limits the current. As the magnetic field builds in winding  300 , the back EMF becomes less and less and the current rises. Once the current reaches a threshold value, current limiting circuitry  654  momentarily shuts off the power. The magnetic field produced by electromagnet windings  300  tapers off, generating a back EMF. Current limiting circuitry  654  then switches power back on to electromagnet windings  300 . This on and off power cycling continues until the motor reaches a sufficient speed to reduce motor currents to a preset level which will not demagnetize motor permanent magnets  358   
     FIG. 43 shows a brushless DC permanent magnet motor of this invention employing current limiting circuitry for preventing demagnetization of rotary permanent magnets. Brushless permanent magnet motor  664  is shown having the front end cap removed to expose the inner workings of the motor. This motor is of the standard construction of many brushless DC permanent magnet motors. Rotor  442  of FIG. 30 is shown inside of electromagnet assembly  365 . Also shown is end cap  338  and small electric generator  452 . Small electric generator  452  puts out a voltage which is proportional to motor RPM values and is used a s part of the current limiting circuitry of this invention. Power output leads  554  and  556  of small electric generator  452  are wired to a relay  453 . Relay  453  is chosen so that it will close at the desired RPM value of the motor based on the output voltage of generator  452 . Also shown is current limiting resistor  666  in series with DC power source  656 . Resistor  666  limits current to a level that will not demagnetize the motor permanent magnets under start up, stall, and low RPM conditions. When rotor  442  reaches a sufficient speed to prevent demagnetization, the output voltage of generator  452  closes relay  453  and shunts resistor  666 . This allows full power from DC power source  656  to be delivered directly to motor  664 . 
     FIG. 44 shows a side view of the high power disc motor of this invention including a small generator on the shaft for speed sensing, speed sensing circuitry, optical timing circuitry, amplification circuitry, and current limiting circuitry. Disc rotor motor  668  is shown in complete form. This particular motor includes a small electric generator  162  which senses the rotor speed by generating a voltage which is proportions to the speed. Generator  162  is of the permanent magnet type and therefore requires no field windings and therefore no input power. Generator  162  can be wired to a relay to shunt a resistor in the usual manner, or modify input power in other ways as well. Generator  162  of motor  668  is wired to power source  656 . Beneath generator  162  of motor  668  is optical encoder  166 . Optical encoder  166  is mounted to motor shaft  152 . The optical encoder itself is shown in detail in FIGS. 14 and 15 previously described. Optical encoder  166  is wired to amplification circuitry  168  which amplifies the signal from the optical encoder  166  and inputs the amplified signal into C-shaped electromagnets  670 . Electromagnets  670  are identical to electromagnets  20  previously described except that electromagnets  670  only require a single set of windings as now the prevention of demagnetization is controlled by limiting the output current of power source  656 . 
     Supported on the motor shaft  152  is rotary disc portion  143  having permanent magnets  54  transversing through the edge of disc  132 . The annular edge portion of disc  132  is rotatably disposed within annular channel  173 . Also shown are flexible plastic fan blades  112  which provide air currents to cool electromagnets  670 . Motor end plates  36  and  38  provide support for motor shaft  152 , electromagnets  670 , and motor bearings  42 . The permanent magnets are disposed on the annular edge portion of disc  132  so that the directions of magnetization thereof transverse through disc  132 . In addition, the poles of the permanent magnets are aligned in coupling proximity to the poles of the electromagnets of the stator.