Abstract:
The dynamo-electric machine comprising a field member creating a flux field extending between magnetic pole portions. There is an armature assembly rotated in the machine comprising a core and a plurality of induction coils. There are switches mounted in the armature assembly so as to be rotatable therewith, and the switches are arranged to cause the current to flow selectively through the coils. By properly controlling the switches to control direction and timing of the current, the current flow in the coils can be optimized to accomplish desired power transfer.

Description:
RELATED APPLICATIONS  
       [0001]    This application is a continuation of Ser. No. 09/561,352 filed Apr. 28, 2000, which is a continuation of Ser. No. 09/015,375 filed Jan. 29, 1998 (now U.S. Pat. No. 6,222,331, and claims priority benefit of U.S. Provisional Ser. No. 60/036,444 filed Jan. 29, 1997. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    a) Field of the Invention  
           [0003]    The present invention relates generally to electrical machines (which include both motors and generators), and more particularly to a system (apparatus and method) for providing power to the machine components and a control and operating system for the same. More particularly, this relates to such a machine and system which does not use brush commutation, and which provides optimized performance of the machine, and also enables the overall design of the machine itself to be improved for better performance.  
           [0004]    One of the more common electrical machines used for various industrial applications is the conventional commutator controlled DC motor having a stator with at least one set (pair) of oppositely positioned fixed north and south poles, and a rotor positioned between the poles. The rotor is wound with coils that extend parallel to the axis of rotation of the rotor and are positioned at circumferentially spaced locations around the rotor.  
           [0005]    Electric power is supplied to the coils of the rotor through the commutator which is interconnected with the rotor and rotates with the rotor. An outside DC power source is connected to the commutator rotor through stationary brushes positioned on opposite sides of the commutator and in electrical contact therewith. The commutator is made up of segments which are in turn connected electrically to the coils in the rotor. Thus, with rotation of the rotor, power is fed from the two brushes to the commutator segments in a predetermined sequence so that the electric current flows through each coil in one direction during one portion of the rotational path of travel of the rotor, and then in the opposite direction during the other portion of the rotational path of the rotor. The commutator is arranged so that the magnetic fields created by the coils interact with the field created by stator to cause the rotation of the rotor.  
           [0006]    Such commutator controlled DC motors have several desirable features for various industrial applications. One significant advantage is that this motor can develop very high torque at startup thus providing a significant advantage over other types of electric motors, such as synchronous motors operating from alternating current. Another advantage of such commutator controlled DC motors for some applications is that the rotational speed of the rotor can be easily changed to match certain operating requirements.  
           [0007]    For example, the motor can develop very high torque at slow speed, and yet under other circumstances, it can operate at much higher speeds.  
           [0008]    However, the commutator controlled DC motors have certain drawbacks, and some of these relate to the problems associated with the commutator and the brushes. It is necessary that the commutator segments be spaced at least a short distance from one another to avoid arcing between adjacent commutator segments.  
           [0009]    However, the brushes must constantly be creating and breaking electrical contact with the rotating commutator segments. This creates maintenance problems. Also, higher costs are involved due to the commutator and brush rigging assembly and other factors. Another drawback is that because of the possible sparking, these are not used in environments where sparking would be hazardous. The practical consequence is a widespread desire to avoid the mechanical commutator apparatus altogether.  
           [0010]    Another drawback related to the brush/commutator control system is that the positioning of the switch-over points is usually a compromise in accordance with the operating conditions of the motor. Ideally, if the motor is operating at a given desired power output and at a given speed, the brushes can be placed at optimized locations so that the switch over of the current supplied to the coils is perfectly timed to optimize the efficiency and other performance characteristics of the rotor. However, if the motor is heavily loaded so that it is required to develop high torque, the rotor will “lag”. The reason for this is that when the rotor is developing high torque, the entire magnetic field between the north and south poles of the stator will bend or distort in a direction opposite to the rotation of the rotor. Thus, in terms of the operating effect of the magnetic fields created, the north and the south poles of the stator actually shift. Also the rotational speed of the motor can affect the optimized position of the brushes.  
           [0011]    Ideally, the commutator brushes should be shifted accordingly so that the switch-over point becomes optimized for that mode of operation.  
           [0012]    Various attempts have been made in the prior art to mechanically shift the brushes or compensate for this situation in other ways, but in large part these attempts have not been successful and/or commercially feasible. Accordingly, quite often the commutator and brushes are placed at a compromise position to accommodate for the various operating conditions that are expected for the motor.  
           [0013]    However, beyond this, in a commutator controlled DC motor, the entire machine design must be compromised in certain respects because of the inherent operating characteristics of the motor. Due to the fact that there is the potential for sparking between the brush and the commutator segments, there is a limit to the level of voltage that can be applied to this type of motor. Also, the air gap between the armature and the rotor has to be greater than a certain minimum distance, because of the induced voltages caused by the commutation of a coil (short circuit) in the coils tends to cause sparking between the commutator segments. One of the disadvantages in having this larger gap is that it increases the reluctance of the magnetic path across the path across the air gap, and thus decreases the torque that can be developed by the motor. This exacerbates the matter by this causing other complications, such as greater distortion of the field when the motor is operating under a heavy load.  
           [0014]    DC generators are substantially the same as (or at least closely similar to) DC motors, but operate in a reverse mode. In other words, in the generator the power input is generally through a rotating shaft, and the output is a DC current.  
           [0015]    In large part, the same advantages and disadvantages that are inherent in DC motors are also present in DC generators.  
           [0016]    Given these disadvantages of such DC motors, one would be led to believe that a motor operating on alternating current would be more desirable, since these do not have the commutator and brush interaction (thus enabling higher voltage machines, with less power loss), and also permitting one to be better able to optimize the motor designs with minimum air gaps and maximum field strengths. To some extent this is true, and such motors have found wide commercial use for some applications. However, such motors operating off alternating current typically suffer from slip, severe lack of start up torque, and a difficulty of control in terms of variable speed.  
           [0017]    In view of this, it is the object of the present invention to provide an improved control system for electric machines in general, and particularly with certain types of electric engines to which the present invention is well adapted to alleviate in large part problems such as described above. Also, the present invention in addition to providing an improved power and control system for electric motors and generators, further comprises, in combination, an electric motor having an optimized design to maximize the benefits provided by the present invention in permitting the motor or generator itself to be designed more effectively, and also to enable more efficient (and in some instances more versatile) operation.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention relates to dynamoelectric machines, which can operate either as a motor or as a generator. The current flow in the coils of the machine can be optimized to accomplish efficient power transfer, and to alleviate many of the problem existing in the prior art.  
           [0019]    The present invention comprises a dynamoelectric machine which comprises a field member and an armature assembly.  
           [0020]    The field member has north and south magnetic portions to create a flux field extending between the magnetic pole portions.  
           [0021]    The armature assembly is rotatably mounted in the machine to rotate through the flux field. The armature assembly comprises:  
           [0022]    a. a core position in the flux field;  
           [0023]    b. coil means comprising a plurality of induction coils positioned adjacent to said core and positioned to move through the flux field during location of the armature assembly;  
           [0024]    c. switch means mounted to the armature assembly so as to be rotatable therewith. The switch means is operatively connected to the coil means, in a manner that current can be caused to flow selectively through the coil means to cause a desired interaction of the coil means in the flux field.  
           [0025]    There is mechanical transfer means connected to the armature assembly so as to be rotatable therewith in power transmitting relationship.  
           [0026]    There is also electrical power transfer means having an operative power connection with the switch means, so that current between the electrical power transfer means and the coil means is selectively controlled by the switch means.  
           [0027]    In addition, there is control means to operate the switch means to control direction and timing of current in said coils. In a preferred embodiment of the present invention, the electrical power transfer means is a direct current electric power transfer means.  
           [0028]    Also in a preferred form, the electrical power transfer means comprises slip ring means rotatably mounted to the armature assembly and brush means operatively engaging the slip means.  
           [0029]    Also, in the preferred form, the control means (or a substantial portion of the control means) is positioned in the armature assembly, so as to be rotatable therewith, and control signal to the control means can be transmitted through the electrical power transfer means.  
           [0030]    There is provided field sensing means positioned relative to the flux field to ascertain orientation and/or other characteristics of the flux field. The sensing means is operatively connected to the control means to enable the control means to modify timing and/or other operation of the switch means to accomplish a proper relationship with the switching relative to the flux field.  
           [0031]    In a more specific form, the sensing mean comprises a plurality of sensors positioned &#39;adjacent to related coils to sense current change and/or condition in related coils. In one specific embodiment, each of the sensors comprises sensor coil means responsive to the flux field, and means responsive to voltage changes in the sensor coil means to send a corresponding signal to the control means.  
           [0032]    In one operating mode, the machine functions as a motor where DC current is directed through the electrical power transfer means to supply power to the armature assembly and cause rotation of the mechanical transfer means.  
           [0033]    In another mode, the machine is operated as a generator, and power is delivered to the mechanical transfer means to cause rotation of the mechanical transfer means so as to generate electricity in the armature assembly which is transmitted to the electrical power transfer means. In several embodiments, the field member comprises status north and south magnetic pole portions so as to provide a status magnetic field.  
           [0034]    In another embodiment, the field member generates a moving flux field which moves circumferentially around the field member.  
           [0035]    Other features of the present invention will become apparent from the following detailed description.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]    [0036]FIG. 1 is a side elevational view of a prior art commutator controlled DC motor, shown partly in section;  
         [0037]    [0037]FIG. 2 is a sectional view taken along line  2 - 2  of FIG. 1, and showing the commutator and brushes;  
         [0038]    [0038]FIG. 3 is a somewhat schematic view illustrating the coils of the rotor of the prior art motor, the commutator, and the electrical connections therebetween;  
         [0039]    [0039]FIG. 4 is a cross sectional view, similar to FIG. 3, illustrating the prior art motor operating under load, along with the resulting shift in the stator field;  
         [0040]    [0040]FIG. 5 is a simplified view showing a single commutator brush engaging the commutator, and also showing the damage to the commutator segments due to sparking;  
         [0041]    [0041]FIG. 6 is a graph illustrating the operating characteristics of three different types of DC motors;  
         [0042]    [0042]FIG. 7 is a schematic view illustrating a prior art DC motor with a starting rheostat;  
         [0043]    [0043]FIG. 8 is an isometric view of a preferred embodiment of the present invention;  
         [0044]    [0044]FIG. 9 is a side elevational view, partly in section, of the motor of FIG. 4;  
         [0045]    [0045]FIG. 10 is a schematic view illustrating the control package of the present invention;  
         [0046]    [0046]FIG. 11 is a schematic drawing of the control circuitry of the present invention;  
         [0047]    [0047]FIG. 12 illustrates one preferred embodiment of the control switches of the present invention, two control switches being shown;  
         [0048]    [0048]FIG. 13 shows another portion of the circuitry, which is an array of MOSFETS, having a switching function;  
         [0049]    [0049]FIG. 14 is an alternative embodiment of the configuration shown in FIG. 9;  
         [0050]    [0050]FIG. 15 shows a preferred embodiment of a monitoring circuit for the present invention.  
         [0051]    [0051]FIG. 16 is a schematic drawing showing the overall system of the present invention;  
         [0052]    [0052]FIG. 17 is a somewhat schematic drawing illustrating the arrangement of the armature coils and the switch and the switches and the switches of a second embodiment of the present invention;  
         [0053]    [0053]FIG. 18 is a schematic view of a third embodiment incorporating the present invention, where the stator comprises four field coils;  
         [0054]    [0054]FIG. 19 is a schematic view of a fourth embodiment, with a modified switching arrangement where each coil has two switch assemblies;  
         [0055]    [0055]FIG. 20 is a schematic view illustrating the present invention incorporated in a motor having the basic operating design of a synchronous motor where alternating current is directed into the stator to create a field which moves synchronously circumferentially around the stator.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0056]    It is believed that a clearer understanding of the present invention will be obtained by first describing in more detail a typical prior art commutator controlled DC motor, such as described in the earlier portion of this text entitled “Background of the Invention”, followed by a further section describing the prior art in general and how this applies to the operating characteristics, advantages and disadvantages of the prior motor (or generator).  
         [0057]    After that, there will be a more detailed description of the present invention. In the following description, it is to be understood that while the preferred embodiment are in many instances called a “motor” (or described as being used in a motor), this same apparatus can be used as a generator. Thus, the apparatus is referred to as “an engine” in part of the text, and in other parts more specifically to a “motor”. It is to be understood, however, that when the term “motor” is used, in most instances this would apply just as well to using this apparatus (i.e. engine) as a generator.  
         [0058]    As a further preliminary comment, in the following two sections references will be made to the book “Electrical Circuits and Machinery”, Volume 1, on Direct Currents, authored by Mr. Frederick Hehr and Mr. George Harness, both of Columbia University. This book bears a copyright notice dated 1940.  
         [0059]    This book provides an informative description of the “dynamo-electric machine” (including both the generator and the motor), and also explains many of the practical aspects in the design and operation of such apparatus. Further, it discusses the different types of motors/generators, the advantages and disadvantages of each, the operating problems encountered, the attempts to solve these, and various applications where the different types of motors/generators would make a good fit, etc.  
         [0060]    It is most interesting to note that although the book was published approximately 58 years prior to the year in which the text of this patent application is being prepared (1998), the contents of this book are in large part quite relevant and informative regarding the advantages, disadvantages, problem areas (and possible solutions of the same) that exist in present day electric machines. The problems and limitations of commutation are discussed in this 1940 treatise in pages 236 through 248. In large part, these still exist in today&#39;s technology. In Chapter VII of that book, “The Direct-current Motor”, there is a description of the various types of DC Motors and their characteristics. On page 334 of that chapter there is discussion of the considerations relevant to start-up of the motor from the time the motor is stationary, and the apparatus required. Again, these same considerations are present with today&#39;s electric motors.  
         [0061]    Thus, even though these operating limitations and problems have been known and analyzed for many decades, and even though there have been certain advancements in the industry to make improvements and adapt to the limitations, the underlying problems and limitations still remain in the present technology relating to electrical machines.  
         [0062]    a) Description of a Prior Art Commutator Controlled DC Motor.  
         [0063]    With reference to FIGS. 1 through 3, there is shown a prior art motor  10  comprising a stator  12  and a rotor  14 . The rotor  14  comprises an output shaft  16 , a commutator  18 , and a pair of brushes  20  and  22 . To supply current to the rotor  14  through the commutator  18 , the brush  20  is connected to a positive power supply  24 , and the brush  22  is connected to a negative power source  26 .  
         [0064]    The rotor  14  has an overall cylindrical configuration, and there is a plurality of coils  28  wound around the rotor core  29 , so that these coils extend longitudinally, parallel&#39; to the axis of rotation of the rotor shaft  16 . The coils  28  extend along the full length of the rotor, and are positioned at evenly spaced circumferential locations, around substantially the entire cylindrical surface  30  of the rotor  14 . The stator  12  comprises north and south pole sections,  32  and  34 , respectively positioned on opposite sides of the rotor  14 . Each of the pole sections  32  and  34  have concavely and cylindrically curved pole faces  36 , and each pole face or surface  36  defines with an adjoining surface portion of the cylindrical surface  30  of the rotor  14  a related cylindrically curved gap  38 .  
         [0065]    Reference is now made to FIG. 3 to illustrate the manner in which the coils  28  are wound in a typical commutator controlled DC motor. (This is shown on page 200 of the aforementioned book “Electrical Circuits and Machinery”—Volume I, Direct Currents).  
         [0066]    In the following several paragraphs there will be a somewhat detailed description of the manner in which the current flows through the seven coils  28  and the commutator segments  40 . It is believed that this review of the operation of the prior art motor will better enable the reader to appreciate the differences in the mode of operation of the present invention compared with the prior art, and also the advantages which can be obtained by the present invention over the common prior art arrangement.  
         [0067]    In the particular motor shown herein, there are seven coils  28 , and the commutator  18  accordingly has seven segments  40 , which are designated by the letters “a” through “g”. The commutator segments  40  are of the same arcuate length and these are located at evenly spaced intervals around the commutator. As shown in FIG. 3, the brushes  20  and  22  are positioned inside the commutator  18 , and this is simply done for purpose of illustration. Normally, the brushes  20  and  22  are positioned on the outside of the commutator, as shown in FIGS. 1 and 2.  
         [0068]    In this particular drawing of FIG. 3, each coil is shown as comprising only a single winding, and each winding comprises a pair of inductor sections  42  positioned diametrically opposite to one another on opposite sides of the core  29  and connected directly to one another at one end by a coil section  44  shown in broken lines in FIG. 3.  
         [0069]    Thus, the coil  1 - 8  comprises two inductor sections, namely section  1  and  8 , and these being shown schematically as a circle to represent the cross section of the coil section. Section  1  shows a dot in the middle of the circle, which indicates that the current is flowing upwardly from the surface of the page, while section  8  shows a plus sign which indicates that the current is flowing downwardly toward the surface of the page. Coil  8  connects through a solid line  48  to the commutator segment “g”, while section  1  connects by another solid line  48  to the commutator section a. As indicated above the bottom ends of inductor sections  1  and  8  are interconnected by a coil portion which is indicated by the broken line  44 . The two inductor sections  1  and  8  extend parallel to the longitudinal axis of the rotor  18 . This same description applies to the other coils  2 - 9 ,  3 - 10 , etc.  
         [0070]    These coil sections  1 - 14   28  are connected through the commutator  18  in series in the following manner. Let us begin at the connecting point  50  of the commutator segment F and travel downwardly from that point along the solid line connection  48  to the coil section  11 , and then back along the broken line  44  to one end of the coil section  4 . The other end of the coil section  4  extends as a solid line to the connecting location at the commutator segment “e”. It will be noted that at that particular location, the two commutator segments “e” and “f” are shorted out by the negative brush  20 . Thus, no current is flowing at that particular instance through the coil sections  4  and  11 .  
         [0071]    To follow this further, let us now follow the flow of current from the commutator segment “e” to the coil section  9 , across to the coil  2 , and then back to the commutator segment “d”. We will see that the series of connection is as follows, e-92-d-7-14-c-5-12-b-3-10-a-1 -8-g-13-6-f-11-4-e.  
         [0072]    Thus, it can be seen that all of the coils are connected end to end in series. It will be noted that in the particular position of FIG. 3, only the commutator segment b is connected to the positive terminal. An analysis of the above connections will indicate that there is a flow of current through various coils from the commutator segment e back to the commutator segment b. This can be seen by looking at the series of connections in the paragraph immediately above which begins with “b” and proceeding to the right toward the coil location “a” and then to the various connecting locations all the way to the computer segment “e”. This can be seen by looking at the series given initially above and proceeding from “e” as follows —e-9-2-d-7-14-c-5-12-b.  
         [0073]    Then there is also a flow of current between the commutator segments f and b as follows . . . f-6-13g-8-1 -a-10-3-b. As indicated above, the commutator segment “e” is shorted out to the commutator segment ‘f’ by the brush  22 .  
         [0074]    From the above, it can be seen that as the rotor  14  rotates further from the position in FIG. 3 in a clockwise direction, the commutator segments “a” and “b” will both be in contact with the positive brush  20 , so that the two connecting points of the coils  3  and  10  will have their two connecting segments “a” and “b” shorted out, so that no current will be flowing through the coil  3 - 10 .  
         [0075]    However, as the rotor  14  continues to rotate to another {fraction (1/14)}th of 3600, the coil sections  3  and  10  will then be in the position that the coil sections  5  and  12  presently occupy in FIG. 3, and current will again begin to flow in the coil sections  3  and  10 , but in the. opposite direction.  
         [0076]    If, at the time a coil is short-circuited by a brush, the coil is cutting across lines of flux an appreciable voltage will be generated in the coil, and a large current will circulate through the path made up of the coil, the commutator segments, and part of the brush itself. This “short-circuited current”, as it is called, can under some circumstances produce disastrous sparking at the brush contact. For this reason, the brushes must be placed on the commutator so that the coil which they short-circuit occupies such a position in the stator magnetic field that little or no voltage is induced in it while it is short-circuited.  
         [0077]    It is to be understood that the winding pattern shown in FIG. 3 is somewhat schematic, and in an actual commercial machine, somewhat different winding patterns may be used. A number of different windings are illustrated in the Hehr and Harness book, and there are shown various multiple circuit windings, wave or series windings, etc. Also, while only two poles are shown in FIG. 3 (and also in this preferred embodiment), there could be (particularly for larger engines) a much larger number of poles.  
         [0078]    b) Discussion of the Operating Characteristics of the Prior Art DC Motor of FIG. 3.  
         [0079]    Much of the description that follows is based upon the information contained in the aforementioned publication “Electric Circuits and Machinery” by Hehr and Harness. Accordingly, in the text that follows in that section, occasional reference will be made to specific pages and sections in that book.  
         [0080]    i. Commutation.  
         [0081]    When each of the coils reaches a position where there is to be current—reversal in that coil, the coil is short-circuited through the commutator. the time in which the reversal of current takes place in a short-circuited coil is very short.  
         [0082]    For example, in a commutator where the diameter is about ten inches, and the rate of rotation is twenty revolutions per second, the time interval available during which the current must reverse fully would be on the order of one one thousandth (0.001) of a second.  
         [0083]    This time period during which a coil is short-circuited by the brush depends upon the peripheral speed of the commutator, the thickness of the brush, and thickness of the insulation between commutator bars. The thickness of the insulation is never greater than fifteen percent of the thickness of a commutator bar or segment.  
         [0084]    The commutation time could be extended by using thicker brushes (i.e. a brush which has a greater arcuate length), but if these are used commutation would begin before the coil is moved out from under a main pole while the coil was still generating voltage.  
         [0085]    During this rapid change of current as indicated previously, the magnetic field around the coil is rapidly collapsing. If the commutation is not properly accomplished, this results in a. high voltage spike, which can cause sparking. The effect of sparking is to cause wearing at the receding edges of the commutator segments and at the trailing brush tips. This is illustrated in FIG. 4, which is derived from a figure printed on page 242 of the Hehr and Harness book.  
         [0086]    In that same book, there is discussed various methods for alleviating the possible problems in commutation. One is EMF commutation where an electromagnetic force is generated at the fringe of the pole. The brushes are advanced on the commutator so that the short-circuited coil lies in edge of the magnetic field under the pole tip.  
         [0087]    Another method is to use commutating poles, which makes brush shifting unnecessary, since the proper commutating flux is brought to the short-circuited coil. To accomplish this, small poles with a series winding are placed midway between the main poles.  
         [0088]    ii. Armature Reaction (Distortion of the Magnetic Field).  
         [0089]    The armature itself tends to set up a magnetic field aligned about 908 to the magnetic field set up by the stator. The effect of this is to distort the static field, and this is illustrated in FIG. 5 (derived from figures shown on page 252 of the Hehr and Harnessbook).  
         [0090]    The distortion is somewhat exaggerated in this particular figure, but it can be seen that there would need to be shifting of the brushes to have them in the proper location so that commutation can properly take place.  
         [0091]    As discussed previously under “Background of the Invention”, when the motor  10  is operating under a heavy load, the rotor  14  will tend to lag.  
         [0092]    In the arrangement shown in FIG. 3 with the rotor  14  rotating in the clockwise direction, the rotor will lag in a counterclockwise direction, and the centers of the north and south fields of stator poles  32  and  36  will effectively shift in a counterclockwise direction. As indicated previously, the shifting of the position of the brushes  20  and  22  to shift the switch over point for various operating conditions has generally not proven to be practical for many (if not most) industrial applications. Accordingly, the setting of the brushes  20  and  22  tends to be something of a compromise.  
         [0093]    iii. Types of Direct Current Motors.  
         [0094]    In Chapter 7 of the Hehr and Harness book, there is described (beginning on page 316) the main three types of DC motors, namely “shunt”, “series”, and compound”. In the shunt wound motor, the field consists of many turns of fine wire and is connected in parallel with the motor armature.  
         [0095]    In the series motor, the field winding has a few turns of heavy wire connected in series with the armature.  
         [0096]    In a compound motor there are two sets of field coils; one of many turns of fine wire and parallel with the armature, and another of a few turns of heavy wire in series with the armature where the motor may be positively connected to its load.  
         [0097]    The compound motor has characteristics between those of a shunt and a series motor and hence has a starting torque greater than that of the shunt motor; but less than that of the series motor. In FIG. 6, which is derived from the figure of page 326 of Hehr and Harness book, the speed and torque characteristics of the three types of motor are shown, where the torque values are along the vertical axis, and current is along the horizontal axis.  
         [0098]    iv. Start Up of the DC Motor.  
         [0099]    When a DC motor is in operation, the current that flows through the inductor coil sections experiences a voltage drop which is the summation of two voltages, (a) the voltage drop component due to the resistance of the wire, and (b) the back EMF resulting from the inductor coil sections passing through the flux field of the stator.  
         [0100]    Current losses equal 12R, where I is the current and R is the resistance. The 12R losses in an electric motor are simply losses, and these are dissipated as heat. Thus, if the current reaches too high a level, it will burn out the motor.  
         [0101]    Let us now examine the practical effect of this in the circumstances where the DC motor is stationary and is to be started. If the stationary armature of a shunt motor is connected directly with the supply line, the current which will flow in the armature current is calculated from the following equation:  
         
       E=Ec+laRa  
     
         [0102]    where E is the total voltage drop  
         [0103]    Ec is the back EMF generated by the coil  
         [0104]    Ta is the armature current  
         [0105]    Ra is the resistance of the coil  
         [0106]    Let us now, take the example of a 110 volt motor, where the current for full load is 40 amperes and the armature resistance of the motor is about 0.2 ohm. When the motor is operating at full power at a rotational speed for which it is designed, most of the voltage drop across the armature coils would be due to the back EMF generated in the coils. However, when the motor is stationary and there is no back EMF, and with 110 volts being applied across the armature, the current through the armature would be 110/0.2, which equals 550 amperes, whereas the full load current is only 40 amperes. This current of 550 amperes would burn out the brushes, commutator, and winding, and would also blow the fuses and circuit breakers in-the supply line.  
         [0107]    However, after the motor is running, there is no excessive current flowing through the armature because the current is limited by the back EMF.  
         [0108]    But while the armature is accelerating, the counter EMF is small and some other means must be employed to limit the starting current.  
         [0109]    There are several devices described in Chapter 7 of the Hehr and Harness publication to resolve this problem, and one of these is shown somewhat schematically in FIG. 7, and derived from the figure shown in page 335 of the Hehr and Harness publication. A rheostat is placed in series with the armature. If the current in the armature is to be sixty amperes of the start (150% of the full load current), the total resistance of the armature circuit must be 110/60, which equals 1.83 ohms. As a rotational speed of the motor increases, then the setting of the rheostat can be moved to lower the resistance until the motor is up to speed, and at that time the rheostat effectively drops out of the circuit.  
         [0110]    The torque developed by the motor is directly related to the strength of the magnetic fields, and the strength of the magnetic fields are directly related to the amount of current flowing in both the stator windings and also the armature coils. Assuming the current in the stator winding is constant, and in this example the current flowing in the armature is, 60 amps (150% of design current), then the armature as it is just starting is developing a very high torque (presumably 150% above the torque it would develop at full power at the design speed). However, since the rotational speed is very slow, and since power output equals force times distance, even though the torque is very high, the effective work done is rather low.  
         [0111]    However, the wasted energy is extraordinarily high and this is being dissipated in rheostat. As the rotational speed of the motor increases, assuming the current stays substantially constant, the power output of the motor goes up in proportion to the rotational speed, and the losses that are dissipated in rheostat diminish.  
         [0112]    In the Hehr and Harness text on page 335, there is mentioned a starting rheostat being in a starting box, and states the following:  
         [0113]    “The wires of which the starting box resistance is composed are imbedded in sand or enamel or wound on porcelain tube: they are then enclosed in fireproof material, so that, if the operator keeps the starting resistance in the circuit for a longer time than that for which it was designed, thus overheating and possibly melting the wire, no risk of fire occurs.” 
         [0114]    In modem day very high powered electric motors the energy dissipating devices are in the form of resistor banks or solid state switches with large heat sinks.  
         [0115]    v. Other Considerations.  
         [0116]    There are various other design and operational considerations relating to speed control, dynamic braking, and other design considerations for increasing efficiency (e.g. brush contact losses, field losses, friction, windage, hysterisis, eddy currents, etc.).  
         [0117]    Further there are practical constraints on the design of electric motors such as a maximum voltage levels imposed by certain design constraints, etc.  
         [0118]    The present invention was designed to in large part eliminate (or at least alleviate) many of these problems, and also to provide an electrical machine with the versatility to operate efficiently in various modes which, in the prior art, can only be approached by making certain design compromises which dictate that the machine be particularly designed for that operating mode.  
         [0119]    With the foregoing being given as background information, let us now direct our attention to the first preferred embodiment of the present invention.  
         [0120]    c) Description of the First Preferred Embodiment.  
         [0121]    Reference is initially made to FIGS. 8 and 9, which illustrates a first preferred embodiment.  
         [0122]    The engine  60  of the present invention (which could be used either as a motor or a generator) comprises a stator  62  and a rotor  64 . (For ease of illustration, the stator  62  is not shown in FIG. 8). The rotor  64  comprises an output shaft  66  and a plurality of coil windings indicated generally at  67 .  
         [0123]    However, instead of having a commutator, as in the common prior art DC motor described in the previous sections, there are provided two slip rings  68  and  70 , operatively engaging related brushes  72  and  74 , which in turn are connected to plus and minus input terminals  76  and  78 .  
         [0124]    Positioned operatively between the slip rings  74  and the rotor  64  is the control assembly  80  of the present invention. This control assembly  80  provides a variety of functions which will be described in more detail later herein.  
         [0125]    To describe further the overall arrangement of the motor  60 , the stator  62  is (or may be) substantially the same as the stator  12  of the prior art motor  10  described above, and thus would comprise a north pole  82  and a south pole  84 .  
         [0126]    There are seven coils  68  wound in a manner similar to (or the same as) the coils  28  of the prior art motor, in that the coils  68  are wound to extend the length of the rotor parallel to the shaft  66 . The coils  67  are connected in series, as described above with regard to the prior art motor. In addition, each end of each coil  67  is connected into the control package  80 .  
         [0127]    Reference is now made to FIG. 10 where the motor  10  is shown schematically.  
         [0128]    In the center of the schematic drawing in FIG. 10, there are shown the seven coils  67 , which for purposes of description have been designated C 1 , C 2 , etc. through C 7 . The coils C 1  through C 7  are connected in a continuous series with an end portion of coil C 1  being connected to an end of C 2 , with the other end of the coil C 2  being connected to an end of coil C 3 , etc., until we arrive back at C 7  being connected to the end of C 1 . The connecting points of the coils C 1 -C 7  are each designated generally as  86 .  
         [0129]    There is a positive and a negative power bus  88  and  90 , respectively, each of these being connected to a related one of the aforementioned slip rings shown as  68  and  70  (shown schematically in FIG. 10 as only plus and minus power inputs).  
         [0130]    There are seven power switch assemblies  92 , these being designated  92 - 1  through  92 - 7 . Each power switch assembly  92 - 1  through  92 - 7  is shown. somewhat schematically in FIG. 10, and will be described more fully later herein with reference to FIG. 10. Each switch assembly  92 - 1  through  92 - 7  comprises a positive power switch  94  and a negative power switch  96 , connected to, respectively, the positive and negative buses  88  and  90 . Each set of power switches  94  and  96  connect at a related common junction point  100 , which in turn connects to a related terminal connection  86  between an adjacent pair of coils  67 .  
         [0131]    To comment briefly at this point on the operation of the present invention, it is evident that by turning on one positive power switch  94  of one switch assembly  92  and turning on a negative switch  96  of another switch assembly  92 , current will flow through the activated positive switch  94  through the coil or coils connected between those switches. It becomes evident that by turning on and turning off the proper switches  94  and  96  of the switch assemblies in proper sequence and with the proper timing, the conducting pattern of the. coils C 1  through C 7  can be controlled in an optimized manner.  
         [0132]    There is also provided for each coil C 1 -C 7  a related coil monitoring device  102 . To describe the function of these briefly, each device  102  senses the related coil.  
         [0133]    During start-up of the motor, these monitoring devices  102  are activated briefly to determine the relative position of each coil relative to the magnetic field of the stator  62 . This enables the control circuitry (to be described hereinafter) to determine how the coils C 1 -C 7  are to be energized to properly start the motor operating.  
         [0134]    In addition, these monitoring devices  102  perform other functions to be described later.  
         [0135]    The circuitry of the control assembly  80  of the present invention is shown in FIG. 11.  
         [0136]    The slip rings  68  and  70 , brushes  72  and  74 , power input terminal  76  and  78 , and also the bus lines  88  and  90  are illustrated schematically in FIG. 11. There is an external control electronics unit  103  that is connected to the stator  62 , and also connects to the brushes  72  and  74 .  
         [0137]    The control circuitry comprises a voltage regulator  104  connected to the bus lines  88  and  90  to provide one or more outputs  106  at a controlled lower voltage level to provide power to the various components of the control circuitry.  
         [0138]    There is a micro processor  108  which can be, for example, either a micro controller (uC), a micro processor (uP), or a digital signal processor (DSP). This unit  108  will hereinafter simply be referred to as the micro processor  108 .  
         [0139]    The micro processor  108  has operative connections (indicated schematically at  110 ) to a plurality of isolated drivers  112  which in turn are attached to respective input terminals  114  (see FIG. 6) of the high voltage power high-side switches  94 .  
         [0140]    There is also a plurality of outputs  116  from the micro processor  108  which connect to a plurality of related (non-isolated) drivers  118 , which in turn connect to the input terminals  120  of the low side switches  96 . In response to the commands of the micro processor  108 , the selected drivers of each set  112  and  118  give an on signal to their respective switches  94  or  96 .  
         [0141]    The NVRAM  120  is a non-volatile RAM which stores data even when the power is totally shut off. The type of data stored would be such things as motor control parameters, operational data, etc. The RAM  122  is what can be termed a “scratch pad” memory (read/write memory), used by the micro-processor for such things as general calculations, data storage, etc. The ROM  124  (read only memory) stores the program which runs the micro-processor.  
         [0142]    An analog multiplexer  126  receives inputs from the pole coil voltage monitoring devices  102 .  
         [0143]    The multiplexer  126  in turn outputs to the analog to digital converter  128  which in turn transmits the data produced in the A/D converter  128  through the line  132  to the micro-processor  108 . The analog to digital converter also communicates through the line  132  with the microprocessor  108  to indicate that it is ready to send data.  
         [0144]    Control signals from the microprocessor  108  are transmitted to both the multiplexer  126  and the analog digital converter  128  through the lines  134  and  136 , respectively.  
         [0145]    To provide communication with the “outside world” (a location exterior of the motor  10 ) there is provided a radio frequency modem  138  which has a communication link  140  with the microprocessor  108  and also with a coupling transformer  142  (comprising the two transformer coils  144  and the core  146 ) which in turn is connected to the two slip rings  68  and  70 . This modem  138  provides a bi-directional coupling system by which low voltage radio frequency signals can be superimposed onto the large voltages flowing into the motor. Thus, information provided from the microprocessor  108  can be transmitted through the modem  138  to a location exterior of the motor  10 , and information can be transmitted to the microprocessor from outside the motor  10 .  
         [0146]    Alternatives are to use RF coupling via antennas or optical coupling.  
         [0147]    [0147]FIG. 12 illustrates two of the power switch assemblies  92  positioned at different location in the motor. The power switch  94  comprises a silicon controlled rectifier (SCR) which has its anode connected to the high bus line  88 , and its cathode connecting to the juncture point  100  that in turn connects to an end of a related coil  67 .  
         [0148]    The power switch  96  also comprises an SCR, but is connected between the common bus line  90  and to an opposite end connection of the coil  67 . The second switch assembly  92  at the lower right end of FIG. 12 is the same as the switch assembly  92  at the upper left part of FIG. 12, thus comprising two silicon controlled rectifiers  94  and  96  similarly connected to the buses  88 . and  90 .  
         [0149]    It is evident by examining FIG. 12 that by turning on one SCR  94  of one switch  92  and simultaneously turning on the SCR  96  of a second switch assembly, current is going to flow through the first SCR  94  through one or more coils  67  to the SCR  96  of the other switch assembly  92  which is to be activated. It is to be understood, of course, that the coil  67  shown in FIG. 12 could actually be several coils in series.  
         [0150]    One of the characteristics of the SCRs used in the switching current of FIG. 12 is that once the SCR  94  or  96  is turned on, it becomes latched, and it will not turn off until there is interruption of current. Therefore, in order to shut off the two switch assemblies  92  shown in FIG. 12, there is employed a switching circuit as shown in FIG. 13.  
         [0151]    In FIG. 13 there is shown an array of MOSFETs  150  arranged both in series and in parallel. There is a first set  152  of MOSFETS  150  arranged in parallel and connected to the supply bus  88 . There is a, . . . second set  154  of MOSFETS  150  connected in parallel with one another, but in series with the MOSFETS  150  of the first set  152 , and in turn connected to the high voltage slip ring  68 . There can also be provided additional sets of MOSFETS sets  156  of MOSFETS connected in parallel and in series between the two sets  152  and  154  of MOSFETS. The reason for this arrangement is that there can be a substantial amount of current flowing to the supply bus  88 , and a MOSFET  150  in parallel enable such large amounts of currents to be carried. By placing the sets  152 ,  154  and  156  in series, the voltage drop across any one set of MOSFETS is reduced.  
         [0152]    The MOSFETS in the switching circuit of FIG. 13 would normally remain conductive.  
         [0153]    However, when it is desired to shut off the SCRs  94 / 96  of the switch assemblies  92  which have been activated, the MOSFETS  150  in FIG. 13 are made non-conductive for a very short period of time to interrupt the current to the switch assemblies  92  of FIG. 12, thus shutting off the SCR&#39;s  94  and  96  that have been conductive. Since there would normally be only two SCR&#39;s  94  and  96  from different switching assemblies  92  on at any one time, this interruption of current does not have any significant adverse effect in the operation of the overall system.  
         [0154]    [0154]FIG. 14 shows an alternative arrangement for the circuitry shown in FIG. 12. The basic configuration of the circuitry in FIG. 14 is the same as in FIG. 12, except that the power switches  94  that are connected to the high voltage slip ring are (instead of being SCRs) insulated gate bipolar transistors (IGBT). Also, the power switches  96  that connect to the common slip ring  90  are MCTs.  
         [0155]    The main difference in the circuitry of FIG. 14 is that both of these devices (the IGTB and the MCT) can be shut off without the necessity of interrupting current flow. Thus, by using the arrangement shown in FIG. 14, it is not necessary to use the current interruption switching circuit of FIG. 13. One benefit of using the circuitry of FIG. 12, or the circuitry of FIG. 13 is that overall, in terms of the prices which exist at the time the text of this patent application is being prepared, the cost of the arrangement of FIG. 12 or  13  would likely be less than the alternative embodiment of FIG. 14. However, if the economics of supplying these components changes, it may turn out that the alternative embodiment FIG. 14 would be more desirable.  
         [0156]    Reference is now made to FIG. 15, which shows a preferred embodiment of a monitoring circuit  102  to sense the voltage at the juncture points  86  between one or more coils  67 . For each juncture point  86 , there are two circuit components  160  and  160   a . The circuit component  160  comprises an LED  164  which is connected between the juncture point  86  and the common supply bus  90 , with a resistor  166  being connected between the LED  164  and the juncture point  86 .  
         [0157]    The brightness of the LED  164  is proportional to the current through the LED, which in turn would be proportional to the voltage between the juncture point  86  and the bus line  90 .  
         [0158]    The LED  164  is positioned to activate an opto-coupler  168 , one terminal of which is connected through a resistor  170  to the voltage source  106  derived from the voltage regulator  104  (See FIG. 11). That same terminal of the opto-coupler  168  also connects to a terminal  172  of the multiplexer. When the opto-coupler  168  is not conductive, then the voltage at the multiplexer terminal  170  is at the voltage level of the voltage at  106 . When the opto-coupler  168  is conductive, then current flows through the resistor  170 , thus lowering the voltage level at the multiplexer terminal  170 , to indicate the voltage at the juncture point  86 .  
         [0159]    The circuit component  160   a  operates in substantially the same way as the circuit component  160  except that the LED  164   a  is connected to the high voltage bus line  88 . Thus, when the voltage at the juncture point  86  is the same as the voltage level at the common line  90 , the current through the LED  164   a  would be at a maximum, to activate the opto-coupler  168   a  and cause a voltage drop at its related photo-coupler terminal  170   a . As the voltage at the juncture terminal  86  rises and reaches the voltage level of the high bus line  88 , then no current would flow through the LED  164   a , and the voltage at the multiplexer terminal  170   a  would thus be the same as at the voltage source  106 . On the other hand, the LED  164  of the circuit component  160  would turn brighter, thus causing the opto-coupler  168  to be conductive and drop the voltage at the multiplexer terminal  170 .  
         [0160]    The sensing circuit of FIG. 15 provides galvanic isolation from the main bus lines  88  and  90 . It is to be understood that other sensing methods could be employed, and still provide the galvanic isolation.  
         [0161]    [0161]FIG. 16 is a schematic view showing the overall system of the present invention. In addition to the sensing and control components described thus far, there is shown in FIG. 16 a sensing means to provide information as to the location of the rotor at any time during its path revolution. This is to be provided quite simply by placing a stationary sensing member  180  on the stator (such as a permanent magnet or coil), and a corresponding sensing unit  182  on the rotor (such as a Hall effect sensor). Each time the rotor makes a complete revolution so that the sensing member  182  comes into proximity with the sensing member  180 , a signal is transferred to the control assembly  80 . Thus, this provides a means to ascertain the precise home index of the rotor  64  at any time in its operation.  
         [0162]    In FIG. 16, there is shown the engine  60  comprising the stator  62  and the rotor  64  (shown rather schematically), with the control assembly  80  being incorporated in the rotor  64 . There is provided an external control electronics unit  170  which is operatively connected through a transformer  172  to the power input terminals  76  and  78 . The same unit  170  is also connected to the stator  62 . One or more input sources can be provided for the external control of electronics unit. First, there is shown a computer  174 ; second a handheld terminal  176 , and third a simple switch control device  178 , which in this illustration is simply shown as an on/off switch.  
         [0163]    In actual practice, other operating controls could also be provided in the switch  178 , such as speed control, power control, etc.  
         [0164]    In operation, the unit  170  would control the current to the stator  62 . In addition, this unit  170  would provide signal inputs to the control assembly  80  in the rotor  64 , and return signals can be sent. The control assembly  80  would be preprogrammed so that it would have the full capacity. to: (a) receive the instructions, and also the inputs from the sensors, (b) ascertain the operating conditions to optimize the performance of the motor (c) and give proper instructions to operate the switch assemblies  92  to cant&#39; out the instructions.  
         [0165]    Each of the power switches  94  and  96  of each switch assembly  92  can be turned on and off very rapidly. By properly controlling the timing of the operation of the switches and also the duration of time on which these switches  94  and  96  are on and off, the following three operating components of the motor can be controlled, namely:  
         [0166]    a. The rotational speed of the motor;  
         [0167]    b. The power output to the motor;  
         [0168]    c. Torque;  
         [0169]    d. The phase angle of the motor.  
         [0170]    As indicated previously, the basic operation of a  
         [0171]    DC electric motor is to direct the current through the appropriate coils and in the properly timed relationship so that the direction of current flow through each coil segment is in the correct direction so that there is the appropriate interaction between the coil field and the stator field to create the torque which is causing the rotation of the rotor. Then when this same coil is traveling out of that stator field and about to enter into the stator field of the  
         [0172]    opposite polarity, then the current must be reversed.  
         [0173]    Also, as indicated previously, the timing of this reversal relative to the magnetic fields that exist within the motor is critical for optimum operating efficiency of the motor.  
         [0174]    In the prior art motor shown in FIG. 3, as described previously, the switching of the current passing through the armature coils is controlled by the commutator. In the present invention, as shown in FIG. 10, the switching is accomplished by the various switch assemblies  92  connected between the coils that are connected in series.  
         [0175]    It is to be understood, of course, that the coils  67  are shown rather schematically in FIG. 10, and in an actual commercial motor, these could be wound in a manner similar to the winding patterns already known in the prior art. For example, in the aforementioned Hehr and Harness book, beginning on page 203 and continuing on through page 216 various methods and patterns of winding the armature coils are given. These are given for bi-polar motors and multiple pole set motors.  
         [0176]    In the arrangement shown in FIG. 10, if the coils C- 1 , C- 2  and C- 3  are to have current flowing in one direction, while the current through the coils C- 7 , C- 6  and C-S are to have the current flowing in the opposite direction, then the positive switch  94  and the switch assembly  92 - 1  would be made conductive, while the negative switches in the coil assemblies  92 - 4  and  92 - 5  would be conductive. The coil C- 4 , would be nonconductive, and this would be expected to occur at such time as the coil C- 4  was between two adjacent stator fields. By causing the proper switching in each of the switch assemblies  92 - 1  through  92 - 7  in “proper sequence, the armature coils will interact with the stator fields to cause rotation of the motor as previously described. To cause rotation of the rotor  64  at the desired rotational speed, the sequence of making the proper switching changes would be either accelerated or decelerated to accomplish greater or less RPM.  
         [0177]    With regard to power input to the motor, for a given set of conditions (and also assuming that the efficiency remains the same), the power output is directly proportional to the current passing through the armature coils times the imposed voltage. In the present invention, the power can be controlled by controlling the amount of time which the current is flowing through each armature coil as it is passing through the stator fields.  
         [0178]    This could be controlled, for example, by switching the current on and off while the coil is passing through the field of that particular stator pole, and controlling the length of the pulses and the time lag between the pulses to obtain the desired power output. Alternatively, in some circumstances, it may be possibly simply to have&#39; a single continuous period of flow of current through the coil as it is passing through that particular, stator field, and simply vary that time period.  
         [0179]    With regard to controlling the phase angle at which armature current switches, this is done by shifting the time period when the switching occurs to reverse the current in the coils. Thus, with reference to FIG. 4, by delaying the switching, the switching point could be moved from the vertical (as shown in FIG. 4) to a more optimized position.  
         [0180]    A desirable feature of the present invention is the versatility it provides. It will be recalled that earlier in this discussion, the different types of DC motors were discussed and also their operating characteristics. These were summarized in FIG. 6. It will be recalled, for example, that as the load increases in a shunt wound motor, the speed will decrease to some extent. In the compound motor the decrease in speed is more pronounced as the current decreases.  
         [0181]    In the present invention, it is possible to maintain the speed. substantially constant as the load increases. This is accomplished by maintaining the same: switching rate for the armature coils, and then controlling the length of time that the current flows in the armature coils to control the torque and bring it to a level so that the current is sufficient to maintain the torque at the appropriate level to match the increase in load.  
         [0182]    Another operating mode for which the present invention provides particular advantages i. the start-up mode. Let us assume that the motor is stationary, and that it is desired to operate the motor with a sufficient torque to accelerate the motor as quickly as possible up to the desired operating speed, and yet not overheat the motor.  
         [0183]    It will be recalled that in prior discussions in this text, this was described as being accomplished in the prior art by dissipating a large percentage of the current generated through a resistance. This was explained with reference to FIG. 7.  
         [0184]    On the other hand, with the present invention, the proper startup torque is obtained by reducing the current to a sufficiently low level (e.g. by transmitting current for shorter periods and/or longer time gaps between the pulses). Thus, in the example given previously in this text where there is a motor which has a maximum practical operating capacity of 40 amps through the armature coils, when this motor is at a standstill and full power is directed through the armature coils, the armature current could go up as high as 550 amperes.  
         [0185]    In the present invention, by turning the armature current on for shorter periods of time, the current flow can be maintained at the desired level to develop the desired torque necessary to start the motor motors is the voltage spikes that can occur when the armature current is reversing, and how this can cause sparking in the brushes. Even though steps are taken in the prior art to alleviate the problem of sparking, these voltage spikes impose a serious limitation on DC motors, in that it limits the voltage differentials that can be employed.  
         [0186]    As a practical matter, in DC motors, the maximum practical voltage differential between adjacent brush connections should be kept below about 20 volts. Also, the necessity of keeping the voltage spikes to a sufficiently low level affects the overall design of the motor in that it limits the width of the gap between the adjacent surfaces of the stator and the rotor. The width of this gap affects the flux across the gap. If this gap is made too small, the flux density can reach a. level which is sufficiently high so that the voltage spike is increased to the level where adverse sparking will occur (with prior art commutation) even though the proper design safeguards are employed.  
         [0187]    In the present invention, the switching of the coils is accomplished without the prior art commutator. Thus, in the present invention, these voltage spikes can be accommodated by making the appropriate switch  94  or  96  in the switch assembly or assemblies  92  conductive for a very short period of time so that the voltage spike is directed into the appropriate power bus as useful power.  
         [0188]    The switching arrangement of a second embodiment of the present invention is disclosed in FIG. 17. Since there is, an even number of inductive armature coils, there will be more than one coil segment which is being switched at a given time. The voltage spike for each of these coil. segments will be opposite to one another. These two voltage spikes can thus be directed simultaneously into the power buses so that these effectively would balance each other without power loss.  
         [0189]    In FIG. 17 there are shown eight separate switches designated A through G. There are eight coils, and each of the numbers  1  through  16  represent individual coil segments. The coil segments are diametrically opposite to one another. Thus, the segments  1  and  9  make up one coil, the segments  2 - 10  make up another coil segment, etc.  
         [0190]    To describe the operation of the arrangement shown in FIG. 17, at anyone time one of switch assemblies (such as shown at  92  in the prior embodiment) has the positive switch made conductive, while an opposite switch assembly has a negative switch made conductive. For example, if switch A is positive and switch E is negative, then there will be a flow of current in one direction through the coil segments on one side of the armature, and a flow of current in the opposite direction in the opposite side of the armature. Then when the next adjacent pair of switches are activated, and the switches in the switch assemblies A and B are turned off, the pattern of the current flow will switch so that the direction of current flows through the coils which are then adjacent to the north and south rotor poles will be traveling in the appropriate direction to continue the proper rotation of the motor.  
         [0191]    [0191]FIG. 18 shows a third embodiment of the present invention, where the a stator of the motor  60   a  comprising two north poles and two south poles, and there are eighteen coils. The switching between the coils is accomplished in generally the same manner as illustrated in FIG. 17. The embodiment of FIG. 18 is shown to illustrate that the present invention can be embodied in a motor where there are multiple north and south poles.  
         [0192]    [0192]FIG. 19 shows a fourth embodiment of the present invention. In this embodiment, there are six coils designated C- 1   b  through C- 6   b . As in the first embodiment, there are switch assemblies  92 , each having positive and negative switches  94  and  95 . However, the individual coils C-lb through C 6   b  are not connected to one another in series.  
         [0193]    Rather, each end of each coil are connected to an individually related switch assembly  92 .  
         [0194]    Thus, in the operation of the embodiment of FIG. 19, each coil is made conductive by turning on the positive switch  94  of one of its related switch assemblies, and at the same time turning on the negative switch  96  of its other related switch assembly  92 . This is done for each coil individually.  
         [0195]    [0195]FIG. 20 shows a fifth embodiment of the present invention where the concept of the present invention is adapted to a design related to a synchronous motor. In a synchronous motor, the flux field is developed through an AC current so that the flux field travels a circumferential path around the stationary outer member (the “stator”).  
         [0196]    In a conventional synchronous motor, the rotor positioned within the stator often simply has permanent magnets with the poles of the magnet being positioned adjacent to the rotating flux field so that the rotational movement of the flux field interacts with the poles of the rotor poles to &#39;ca use the rotor to rotate synchronously with the field traveling: around the circumference of the stator.  
         [0197]    To incorporate the present invention in the basic design of a synchronous motor, the rotor, instead, of being provided as permanent magnets, is provided&#39; with an armature made in accordance with the present invention having&#39; the. switching and control assembly of the present invention. The switching assembly of the armature is connected to DC field windings (as in the prior embodiments) where there are plus and minus brushes operatively connected to slip rings that rotate with the armature.  
         [0198]    The operation of this fifth embodiment is substantially the same as in the first embodiment, except that the rotational movement of the flux field is superimposed, so as to be added or subtracted to the rotational movement caused by the, switching of the armature currents in its coils. Thus, if the flux field is rotating counterclockwise, and the armature currents are switched so that these would cause clockwise. rotation if the flux field were static, then the rotational component of travel provided by the switching of the armature currents would be added to the rotational component provided by the rotating flux field. On the other hand, if the current pattern in the armature is reversed to cause counterclockwise movement, then the clockwise rotational movement of the flux field and the rotational component of the armature would be subtracted from one another.  
         [0199]    With regard to the advantage provided by incorporating the present invention in the general design of an AC synchronous motor, it will be recalled that earlier in this text it was mentioned that one of the drawbacks of this synchronous motor is that its rotational speed is dictated by the rotational speed of that of the field imposed on the synchronous motor. A further limitation was that the start-up torque was rather poor. However, by using the principles of the present invention in such motor, the rotational speed can be varied all the way from zero to a: speed substantially greater, than the rotational, speed of the field. Thus, the utilization of the present. invention in&#39; this particular embodiment creates greater versatility in the selection of its operating modes.  
         [0200]    In the earlier part of the text of this patent application, it was indicated that the apparatus of the present invention can operate as either a motor or a generator. This is true of all the embodiments disclosed herein.  
         [0201]    Accordingly, while much of the description herein has been directed specifically toward the use of the present invention where the machine operates as a motor, the same principles could be incorporated in this same or similar apparatus being used as a generator.  
         [0202]    To review rather briefly how this is done.  
         [0203]    When the apparatus is used for the generator, the power input is a mechanical power input which supplies power to the armature to rotate the armature. The inductive coils move through the stator field to cause current to flow through the armature coils, and this current flows through the control assembly  80  through the slip rings  68  and  70  and are delivered to the brushes  72  and  74  as direct current. The operation as a motor has been described earlier herein in detail, so this will not be repeated.  
         [0204]    It should be understood that various modification could be made to the present invention without departing from the basic teachings thereof.