Abstract:
An electrical generator comprising a stator having stator windings and a rotor having rotor windings. The rotor and the rotor windings extend about the stator windings. The rotor includes an annular rotor housing. On an inside of the rotor housing are mounted the rotor windings. The stator includes an end member with a central member extending therefrom. The stator windings are mounted on the central member. The stator also includes an annular stator housing that extends about the central member, including the stator windings, and the rotor. The end member attaches to the stator housing thereby positioning the stator windings in a central location. The stator housing and the end member enclose the stator windings and the rotor windings therein. The rotor housing further includes a rotor mounting member on an end. The stator housing includes a stator mounting member on an end thereof, and a stator windings mounting member on an opposite end. The stator windings include an exciter field winding and a generator armature winding. The rotor windings include an exciter armature winding and a generator field winding. The exciter armature winding is disposed radially outwardly from and adjacent to the exciter field winding. The generator field winding is disposed radially outwardly from and adjacent to the exciter armature winding.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to electrical machines having centrally disposed stators and, in particular, to electrical generators having centrally disposed stators.  
         [0002]     Conventional electrical generators have made use of a permanent magnet to provide a DC magnetic field, such as disclosed in U.S. Pat. No. 4,900,959, issued Feb. 13, 1990 to Drinkut et al. This limits the usefulness of the electrical generator in many applications requiring the excited magnetic field to be controlled, which is not possible when using permanent magnets. As disclosed in Drinkut et al., conventional electrical generators further include a generator shaft and bearing to attach to the rotor for rotation. This complicates the mounting of the electrical generator on a rotational means, such as found on an engine. Additionally, these electrical generators have made use of DC current collection rings to route the generated power off of the rotor to be used by a load. This decreases the reliability and rotational speed of such generators.  
       SUMMARY OF THE INVENTION  
       [0003]     A first aspect of the present invention includes an electrical generator comprising a stator having stator windings, and a rotor having rotor windings. The rotor and the rotor windings extend about the stator windings. The rotor includes an annular rotor housing. On an inside of the rotor housing are mounted the rotor windings. The stator includes an end member with a central member extending therefrom. The stator windings are mounted on the central member. The stator also includes an annular stator housing that extends about the central member, including the stator windings, and the rotor. The end member attaches to the stator housing thereby positioning the stator windings in a central location. The stator housing and the end member enclose the stator windings and the rotor windings therein.  
         [0004]     The rotor housing further includes a rotor mounting member at an end, which can be a flange extending radially inwardly from the rotor housing. The rotor mounting member is used to mount the rotor to a rotatable member.  
         [0005]     The stator housing includes a stator mounting member at an end thereof, and a stator windings mounting member at an opposite end. The stator mounting member can be a flange extending radially outwardly from the stator housing, and the stator windings mounting member can be a flange extending radially inwardly from the stator housing.  
         [0006]     The stator windings include an exciter field winding and a generator armature winding. The rotor windings include an exciter armature winding and a generator field winding. The exciter armature winding is disposed radially outwardly from and adjacent to the exciter field winding.  
         [0007]     The generator field winding is disposed radially outwardly from and adjacent to the exciter armature winding. The generator field winding includes an annular core. The annular core includes an inside annular surface and a plurality of members, each said member having a first side, a second side and an end. The first side and the second side of each said member project radially inwardly from the inside annular surface towards the end. Each said member has a projection extending from the first side near the end. A coil is mounted on each said projection.  
         [0008]     In a second aspect of the present invention the generator field winding includes an annular core with an inside annular surface and a side surface, the inside annular surface has a plurality of recesses. The generator field winding also includes a plurality of winding members. Each said winding member has a protrusion that is mutually engageable with each said recess. A coil is mounted on each said winding member. The winding member further includes a body member and a protrusion. The body member has a pair of sides and an end. The body member extends from the protrusion, along the pair of sides, towards the end. The projection extends from one of the pair of sides near the end. The coil is mounted on the projection.  
         [0009]     In a third aspect of the present invention a method is provided to mount the electrical generator to an engine. The method comprises the steps of aligning a rotor having rotor windings and a rotor mounting member to a flywheel. Then, connecting the rotor mounting member to the flywheel. Next, connecting the stator housing having a stator mounting member and a stator windings mounting member to an engine block, the stator housing enclosing the rotor. Finally, connecting an end member to the stator windings mounting member, the end member having a central member with stator windings mounted thereon.  
         [0010]     The inside-out geometry of the present embodiment provides many advantages. It allows for elimination of a generator shaft and generator bearing. The relatively large diameter of the rotor mounting member results in very good structural strength. This eliminates the need for an outboard support bearing, as is commonly known in the art, and permits a cantilevered design.  
         [0011]     A high rotational inertia is also achieved with the inside-out geometry. This fulfills a need that exists when the generator is used on small diesel engines. Since the rotor lies radially outwardly of the stator windings, it has the necessary rotational inertia for small diesel engines without adding excessive weight.  
         [0012]     Another advantage of the inside-out geometry is its thermal characteristic. The location of the generator field winding around an inner periphery of the rotor housing, next to the stator housing, provides significantly more cooling surface than if it was located radially within the stator windings. The generator field winding can expel its heat losses to the surrounding stator housing. Additionally, the inside-out geometry allows for air ventilation openings in the rotor to allow for some passive circulation of air in and around the rotor windings to provide cooling.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The present invention will be more readily understood from the following description of preferred embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which:  
         [0014]      FIG. 1  is an exploded isometric view of an electrical machine according to one embodiment of the present invention;  
         [0015]      FIG. 2  is a cross-sectional view of the electrical machine of  FIG. 1 ;  
         [0016]      FIG. 3  is an end view of an exciter field winding, partially wound, having symmetric coil projections of the electrical machine of  FIG. 1 ;  
         [0017]      FIG. 4  is an end view of an exciter armature winding of the electrical machine of  FIG. 1 ;  
         [0018]      FIG. 5  is an end view of a generator field winding, partially wound, having asymmetric coil projections of the electrical machine of  FIG. 1 ;  
         [0019]      FIG. 6  is an end view of a generator armature winding of the electrical machine of  FIG. 1 ;  
         [0020]      FIG. 7  is an end view of a modular generator field winding according to another embodiment of the present invention.  
         [0021]      FIG. 8  is a cross-sectional view of an electrical machine according to another embodiment of the present invention.  
         [0022]      FIG. 9  is a view in perspective of a rotor of an electrical machine according to another embodiment of the present invention.  
         [0023]      FIG. 10  is an end view of the rotor of the electrical machine of  FIG. 9 .  
         [0024]      FIG. 11  is a view in cross-section taken along line A-A of the rotor of  FIG. 9 .  
         [0025]      FIG. 12  is an exploded side view of a stator of the electrical machine of  FIG. 9 .  
         [0026]      FIG. 13  is a side view of the stator of the electrical machine of  FIG. 9 .  
         [0027]      FIG. 14  is an end view of the stator of the electrical machine of  FIG. 9 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Referring to the drawings and first to  FIG. 1 , this shows a preferred embodiment of the present invention. An electrical generator  31  is illustrated with an inside-out geometry. The electrical generator  31  has a stator and an annular rotor indicated generally by reference numerals  26  and  12  respectively. The electrical generator  31  is a brushless generator in this example. The electrical generator  31  provides a DC voltage and a DC current to a load in this example, but in other embodiments the electrical generator may provide an AC voltage and an AC current to an AC load, or both AC and DC voltages and AC and DC currents may be provided to AC and DC loads respectively. The stator  26  has an exciter field winding  20  and a generator armature winding  18 , collectively referred to as the stator windings, extending about an outer periphery of a central member  21 . The central member  21  is attached to an end member  23  so as to centrally locate the stator windings  18  and  20  inside the rotor  12 . The end member  23  is connected to a stator housing  10  that encloses the rotor  12  and the stator windings  18  and  20  as seen in  FIG. 2 . The rotor  12  comprises an exciter armature winding  14  and a generator field winding  16 , collectively referred to as the rotor windings, on an inside of an annular rotor housing  28 .  
         [0029]     The alignment between the stator windings  18  and  20  and the rotor windings  14  and  16  is illustrated in  FIG. 2 . The exciter field winding  20  is adjacent to and disposed radially inwardly from the exciter armature winding  14 . The exciter field winding  20  comprises an exciter field annular core  36  and a plurality of exciter field coils  34 . The exciter field annular core  36  may comprise a solid core or may comprise a plurality of laminations. The exciter armature winding  14  comprises an exciter armature annular core  30  and a plurality of exciter armature coils  32 . The exciter armature annular core  30  comprises a plurality of laminations in this example.  
         [0030]     The exciter field winding  20  is excited by an exciter field current, for example a DC current from a battery or a DC current from a control system. In other embodiments the exciter field current may be a pulsed current or an AC current. The exciter field current flows through the exciter field coils  34 , creating an exciter field magnetic field. The exciter armature coils  32  on the rotor  12  rotate through the exciter field magnetic field. This induces an exciter armature current to flow through the exciter armature coils  32 . The exciter armature current is an AC current. [ 0017 ] The generator field winding  16  and the generator armature winding  18  are now described in greater detail. The generator field winding  16  is adjacent to and disposed radially outwardly from the generator armature winding  18 . The generator field winding  16  comprises a generator field annular core  38  and a plurality of generator field coils  40 . The generator field annular core  38  may comprise a solid core or may comprise a plurality of laminations. The generator armature winding  18  comprises a generator armature annular core  44  and a plurality of generator armature coils  42 . The generator armature annular core  44  comprises a plurality of laminations in this example.  
         [0031]     The AC exciter armature current is rectified by a rectifier assembly  80 , described in more detail below, creating a DC generator field current in this example. The generator field current flows through the generator field coils  40 , creating a static generator field magnetic field. Since the generator field coils  40  are part of the rotor  12  which rotates about a rotor axis  17 , the generator field magnetic field itself rotates about the rotor axis. The generator field magnetic field changes over time and space with respect to the generator armature coils  42  on the stator  26 . This induces an AC generator armature voltage in the generator armature coils  42  which can be applied to an AC load, or rectified into a DC generator armature voltage and applied to a DC load. In other embodiments, the exciter armature AC current is not rectified, but instead is applied directly to the generator field coils  40 , which creates an alternating generator field magnetic field.  
         [0032]     Also illustrated in  FIG. 2  is a rotor mounting member  22  connected to the rotor housing  28 . The rotor mounting member  22  extends radially inwardly from the rotor housing  28 , in this example, and is used to connect the rotor  12  to a rotatable member, e.g. a flywheel of an engine. In the present embodiment the rotor mounting member  22  is a rotor mounting flange.  
         [0033]     The stator  26  includes a stator mounting member  13  located on an end  19  of the stator housing  10 . The stator mounting member  13  extends radially outwardly from the stator housing  10  in this example, and is used to connect the stator  26  to a stationary member, for example an engine block of the engine. The stator mounting member  13  is a stator mounting flange in the present embodiment.  
         [0034]     The stator  26  also includes a stator windings mounting member  11  located on an end  21  of the stator housing  10  opposite end  19 . The stator windings mounting member  11  extends radially inwardly from the stator housing  10 , in this example, and is used to connect the end member  23  along with the central member  21  and the stator windings  18  and  20  to the stator housing  10 . In the present embodiment, the stator windings mounting member  11  is a stator windings mounting flange.  
         [0035]     In this example the rectifier assembly  80 , illustrated in  FIG. 2 , is mounted on the inside of the rotor  12  between the exciter armature winding  14  and the generator field winding  16 . However, in other embodiments the rectifier assembly  80  may be mounted in other locations, such as next to the stator windings mounting member  11 , or next to the rotor mounting member  22 . The rectifier assembly  80  in this example includes two bridge rectifiers and a termination assembly. The bridge rectifiers are located 120 degrees apart along an inner periphery of the rotor housing  28 . The termination assembly is mounted equidistant from the two bridge rectifiers along the same periphery.  
         [0036]     The rectifier assembly  80  is connected to the exciter armature coils  32  and to the generator field coils  40 . It operates to rectify the AC exciter armature current into the DC generator field current.  
         [0037]     The inside-out geometry of the present embodiment provides many advantages. It allows for elimination of a generator shaft and generator bearing. The relatively large diameter of the rotor mounting member  22 , in this case a flange, results in very good structural strength. This eliminates the need for an outboard support bearing, as is commonly known in the art, and permits a cantilevered design as described above.  
         [0038]     A high rotational inertia is also achieved with the inside-out geometry. This fulfills a need that exists when the generator is used on small diesel engines. Since the rotor  12  lies radially outwardly of the stator windings  18  and  20 , it has the necessary rotational inertia for small diesel engines without adding excessive weight.  
         [0039]     Another advantage of the inside-out geometry is its thermal characteristic. The location of the generator field winding  16  around an inner periphery of the rotor housing  28 , next to the stator housing  10 , provides significantly more cooling surface than if it was located radially within the stator windings  18  and  20 . The generator field winding  16  can expel its heat losses to the surrounding stator housing  10 . Additionally, the inside-out geometry allows for air ventilation openings in the rotor  12  to allow for some passive circulation of air in and around the rotor windings  14  and  16  to provide cooling.  
         [0040]     The exciter field winding  20  is now described in more detail.  FIG. 3  shows an end view of the exciter field winding  20 . The exciter field winding  20  includes the exciter field annular core  36  which has a plurality of radially outwardly extending members  37 . In this example, each member  37  is symmetrical and extends from an outside annular surface  41  of the annular core  36 . Each member  37  has a pair of lateral projections  35 , in this example. The pair of lateral projections  35  are also known as pole tips. In other embodiments the member  37  can be asymmetrical having a single lateral projection. One of the exciter field coils  34  is mounted on each of the members  37 . Only one of these coils is illustrated in  FIG. 3 , similar coils being mounted on the other five members in this example.  
         [0041]     The exciter field annular core  36  has a plurality of notches  39 , three in this example, and a projection  45  on an inner annular surface  43 . The notches  39  and projection  43  provide alignment between the annular core  36  and the central member  21 , which has complementary projections and notch, and serve to carry the torque that is present between the annular core and the central member during operation.  
         [0042]     The exciter armature winding  14  is now described in more detail. Referring to  FIG. 4 , this illustrates an end view of the exciter armature annular core  30  having a plurality of exciter armature projections indicated generally by reference characters TE 1  through TE 18 . In this example, the plurality of exciter armature coils  32  includes three coils per phase for a total of nine coils, indicated generally by reference characters CPA 1 , CPA 2  and CPA 3  for phase A, CPB 1 , CPB 2  and CPB 3  for phase B, and CPC 1 , CPC 2  and CPC 3  for phase C. This example exemplifies a one coil side per slot arrangement. In other embodiments there can be a different number of exciter armature coils  32 , for example, a two coil side per slot arrangment. The exciter armature coils  32  in the same phase are connected in parallel in this example, however they can be connected in series, or in series-parallel combinations or in groups of parallel connections with coils in a group being connected in series-parallel combinations. Each of the exciter armature coils  32  spans three exciter armature projections, e.g. the exciter armature coil CPA 1  spans exciter armature projections TE 1  through TE 4 , as illustrated schematically by way of example only in  FIG. 4 .  
         [0043]     The phase A coils CPA 1 , CPA 2  and CPA 3  have corresponding phase leads LA 1 , LA 2  and LA 3  and neutral connections NA 1 , NA 2  and NA 3  respectively. The phase leads LA 1 , LA 2  and LA 3  are connected together to form the phase A lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 . The phase B coils CPB 1 , CPB 2  and CPB 3  have corresponding phase leads LB 1 , LB 2  and LB 3  and neutral connections NB 1 , NB 2  and NB 3  respectively. The phase leads LB 1 , LB 2  and LB 3  are connected together to form the phase B lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 . The phase C coils CPC 1 , CPC 2  and CPC 3  have corresponding phase leads LC 1 , LC 2  and LC 3  and neutral connections NC 1 , NC 2  and NC 3  respectively. The phase leads LC 1 , LC 2  and LC 3  are connected together to form the phase C lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 .  
         [0044]     The generator field winding  16  is now described in more detail.  FIG. 5  shows an end view of the generator field winding  16 . The generator field winding  16  includes the generator field annular core  38  having a plurality of inwardly extending asymmetric members indicated generally by reference numeral  52 . The asymmetric members  52  are also known as asymmetric magnetic pole tips. The generator field annular core  38  lies in a plane corresponding to the illustration in  FIG. 5 . Each member  52  is located in the plane and extends from an inside annular surface  50  of the annular core  38 . Each member  52  has a first side  54 , a second side  56  and an end  58 . The first side  54  and the second side  56  project radially inwardly from the surface  50  towards the end  58 . Furthermore, each member  52  has a lateral projection  60  in the plane and which extends from the first side  54  near the end  58 . One of the generator field coils  40  is mounted on each of the members  52 . Only one of these coils is illustrated in  FIG. 5 , similar coils being mounted on the other seven members.  
         [0045]     The generator field annular core  38  also has a notch  53  along an outer surface  55 . The notch  53  is for aligning the annular core  38  with a complementary projection on the rotor housing  28  during assembly of the rotor  12 , and serves to carry the torque that is present between the annular core and the rotor housing during operation.  
         [0046]     The asymmetric member  52  allows the generator field coils  40  to be preformed and then mounted on the generator field annular core  38 . This has many advantages including decreased manufacturing cost due to a reduction in manufacturing time and complexity of the generator field winding  16 . Since the coils  40  may be preformed before being mounted on the cores  38 , they can be wound by a machine. Machine wound coils have individual coil loops that are tightly spaced, as opposed to manually wound coils. This increases the number of turns in each coil thus increasing an ampere-turns per pole which correspondingly increases the magnetic field strength of the pole. The generator field coils  40  can also be machine wound directly onto the members  52  of the annular core  38 .  
         [0047]     The generator armature winding  18  is now described in more detail. Referring to  FIG. 6 , this illustrates an end view of the generator armature annular core  44  having a plurality of exciter armature projections indicated generally by reference characters TA 1  through TA 24 . In this example, the plurality of generator armature coils  42  includes four coils per phase for a total of twelve coils, indicated generally by reference characters GCPA 1 , GCPA 2 , GCPA 3  and GCPA 4  for phase A, GCPB 1 , GCPB 2 , GCPB 3  and GCPB 4  for phase B, and GCPC 1 , GCPC 2 , GCPC 3  and GCPC 4  for phase C. This example exemplifies a one coil side per slot arrangement. In other embodiments there may be a different number of generator armature coils  42 , for example a two coil side per slot arrangement. The generator armature coils  42  in the same phase are connected in parallel in this example, however they can be connected in series, or in series-parallel combinations or in groups of parallel connections with coils in a group being connected in series-parallel combinations. Each of the generator armature coils  42  spans four generator armature projections, e.g. the generator armature coil GCPA 1  spans generator armature projections TA 1  through TA 4 , as illustrated schematically by way of example only in  FIG. 6 .  
         [0048]     The phase A coils GCPA 1 , GCPA 2 , GCPA 3  and GCPA 4  have corresponding phase leads GLA 1 , GLA 2 , GLA 3  and GLA 4  and neutral connections GNA 1 , GNA 2 , GNA 3  and GNA 4  respectively. The phase leads GLA 1 , GLA 2 , GLA 3  and GLA 4  are connected together to form the phase A lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 . The phase B coils GCPB 1 , GCPB 2 , GCPB 3  and GCPB 4  have corresponding phase leads GLB 1 , GLB 2 , GLB 3  and GLB 4  and neutral connections GNB 1 , GNB 2 , GNB 3  and GNB 4  respectively. The phase leads GLB 1 , GLB 2 , GLB 3  and GLB 4  are connected together to form the phase B lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 . The phase C coils GCPC 1 , GCPC 2 , GCPC 3  and GCPC 4  have corresponding phase leads GLC 1 , GLC 2 , GLC 3  and GLC 4  and neutral connections GNC 1 , GNC 2 , GNC 3  and GNC 4  respectively. The phase leads GLC 1 , GLC 2 , GLC 3  and GLC 4  are connected together to form the phase C lead which is brought out of the electrical generator  31 . The neutral connections are connected together and remain internal to the electrical generator  31 .  
         [0049]     Another embodiment of the present invention is illustrated in  FIG. 7 , where like parts have like reference numerals appended by “0.1”. This embodiment is similar to the previous embodiment with differences as follows. A generator field winding  16 . 1  comprises an annular core  38 . 1 , a plurality of modular winding members  64  and a plurality of generator field coils  40 . 1 . The annular core  38 . 1  lies in a plane corresponding to the illustration of  FIG. 7 . The annular core  38 . 1  has a side surface  62  and an inside annular surface  50 . 1 . The inside annular surface  50 . 1  has a plurality of recesses  63  extending from the side surface  62 . One such recess  63  is illustrated in  FIG. 7 , the remaining recesses are shown engaged with the said winding members  64 .  
         [0050]     Each said winding member  64  lies in the plane and has a protrusion  66  and a body  70 . The protrusion  66  is mutually engageable with the recess  63 , and in this example the protrusion and recess form what is known as a dovetail. The body  70  has a pair of sides  72  and an end  74 . The body  70  extends from the protrusion  66 , along the pair of sides  72 , towards the end  74 . A projection  76  extends from one of the pair of sides  72  near the end  74 . One of the generator field coils  40 . 1  is mounted on each of the members  64 . Only one of these coils is illustrated in  FIG. 7 , similar coils being mounted on the other members.  
         [0051]     The generator field annular core  38 . 1  also has a plurality of notches  53 . 1 , three in this example, along an outer surface  55 . 1 . The notches  53 . 1  provide alignment between the annular core  38 . 1  and complementary projections on the rotor housing  28 , and serve to carry the torque that is present between the annular core and the rotor housing during operation.  
         [0052]     The generator field coils  40 . 1  in this example are machine wound on the plurality of winding members  64 , after which each said winding member  64  is engaged with one of said recesses  63  of the annular core  38 . 1 . The advantages of this second embodiment of the generator field winding  16 . 1  are the same as the previous embodiment above. Furthermore, the annular core  38 . 1  can comprise either solid core technology or laminations.  
         [0053]     In another embodiment of the present invention illustrated in  FIG. 8 , wherein like parts have like reference numerals with the extension “0.2”, an electrical generator  31 . 2  is connected to a flywheel  90  and an engine block  92 . The electrical generator  31 . 2  is similar to the electrical generator  31  of the prior embodiment. The flywheel  90  is a rotatable member for rotating the rotor. The engine block  92  is a stationary member for mounting the stator.  
         [0054]     Another advantage of the present invention is the ability to quickly mount the electrical generator  31 . 2  on an engine or to remove therefrom. The electrical generator  31 . 2  is mounted on the engine by performing the following steps with reference to  FIG. 8 . A rotor  12 . 2  is aligned with the rotatable member, which in the present embodiment is the engine flywheel  90 . A rotor mounting member  22  is connected to the engine flywheel  90 , typically with bolts. A stator housing  10 . 2  is aligned with the stationary member, which in this embodiment is the engine block  92 . A stator mounting member  13 . 2  is connected to the engine block  92 , typically with bolts. An end member  23 . 2 , including a central member  21 . 2 , an exciter field winding  20 . 2  and a generator armature winding  18 . 2 , is aligned with the stator windings mounting member  11 . 2 . The end member  23 . 2  is connected to the stator windings mounting member  11 . 2 , typically with bolts.  
         [0055]     The removal procedure is the opposite to the mounting procedure. Note that after the end member  23 . 2  is removed from the stator housing  10 . 2 , the rotor  12 . 2  can be removed from the rotatable member without removing the stator housing  10 . 2 .  
         [0056]     Another embodiment of the present invention is illustrated in  FIGS. 9-14 , wherein like parts have like reference numerals with the extension “0.3”. This embodiment is similar to the first embodiment. Referring first to  FIGS. 9-11 , there is shown a rotor  12 . 3  including an exciter armature winding  14 . 3 , a generator field winding  16 . 3  and a rotor housing  28 . 3 . A rectifier assembly  98  is connected to an end of the rotor  12 . 3 . In this example, the rectifier assembly  98  includes two bridge rectifiers and a termination assembly mounted on a printed circuit board (PCB). The bridge rectifiers are located  120  degrees apart along an outer periphery of the PCB, the termination assembly is mounted equidistant from the two bridge rectifiers along the same periphery.  
         [0057]     Now referring to  FIGS. 12-14 , there is shown a stator  26 . 3 . The stator  26 . 3  includes a central member  21 . 3 , an end member  23 . 3 , an exciter field winding  20 . 3  and a generator armature winding  18 . 3 .  
         [0058]     An advantage of the rectifier assembly  98  is its convenient and accessible location for inspection and repair. Only the end member  23 . 3  needs to be removed from the electrical generator to provide access to the rectifier assembly  98 .  
         [0059]     As will be apparent to those skilled in the art, various modifications may be made within the scope of the appended claims.