Abstract:
A fuel/electric drive system having an internal combustion engine is disclosed, having a generator which is driven by the internal combustion engine and has a first stator winding set, having a first rectifier which is connected to the first stator winding set at the AC voltage end and to a first DC voltage circuit at the DC voltage end, and having a first inverter which is connected to the first DC voltage circuit at the DC voltage end and to a drive motor at the AC voltage end. In order to increase the robustness and availability of the fuel/electric drive system, the generator has a second stator winding set, with a second rectifier being connected to the second stator winding set at the AC voltage end and to a second DC voltage circuit at the DC voltage end, and a second inverter being connected to the second DC voltage circuit at the DC voltage end and to the drive motor at the AC voltage end.

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application 60/759,053 filed in the U.S. on Jan. 17, 2006, and as a continuation application under 35 U.S.C. §120 to PCT/CH2006/000156 filed as an International Application on Mar. 16, 2006 designating the U.S., the entire contents of which are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to the field of drive systems. It is based on a fuel/electric drive system. 
     BACKGROUND INFORMATION 
     Nowadays fuel/electric drive systems are being increasingly used in marine applications as well as rail-bound vehicles and in automobiles. Such a known fuel/electric drive system is shown by way of example in  FIG. 1 . In said figure, the contemporary fuel/electric drive system has an internal combustion engine and a generator which is driven by the internal combustion engine. A transmission is typically connected between the internal combustion engine and the generator. The generator typically has a single stator winding set. A rectifier is connected on the alternating voltage side to this stator winding set. The rectifier is also connected on the direct voltage side to a direct voltage circuit, with a power inverter for feeding a drive motor being connected to the direct voltage circuit. 
     The problem with a known fuel/electric drive system described above, in particular the fuel/electric drive system according to  FIG. 1 , is that when the generator fails, for example due to a fault or short circuit in one of the stator winding sets, the drive motor can no longer be fed sufficiently and the entire drive system is therefore no longer available. In addition, the downstream elements, such as the rectifier, direct voltage circuit, power inverter and drive motor, can be damaged when the generator fails. 
     SUMMARY 
     Exemplary embodiments disclosed herein can make available a robust fuel/electric drive system which also has a high level of availability. 
     A fuel/electric drive system having an internal combustion engine, having a generator which is driven by the internal combustion engine and which has a first stator winding set, having a first rectifier which is connected on the alternating voltage side to the first stator winding set and on the direct voltage side to a first direct voltage circuit, having a first power inverter which is connected on the direct voltage side to the first direct voltage circuit and on the alternating voltage side to a drive motor, wherein the generator has a second stator winding set, in that a second rectifier is connected on the alternating voltage side to the second stator winding set and on the direct voltage side to a second direct voltage circuit, and in that a second power inverter is connected on the direct voltage side to the second direct voltage circuit and on the alternating voltage side to the drive motor. 
     In another aspect, a fuel/electric drive arrangement is disclosed based on a generator. Such an exemplary drive arrangement comprises a first stator winding set; a first direct voltage circuit; a first rectifier which is connected on an alternating voltage side to the first stator winding set and on a direct voltage side to the first direct voltage circuit; a drive motor; a first power inverter which is connected on a direct voltage side to the first direct voltage circuit and on an alternating voltage side to the drive motor; a second stator winding set; a second direct voltage circuit; a second rectifier connected on an alternating voltage side to the second stator winding set and on a direct voltage side to the second direct voltage circuit; and a second power inverter connected on a direct voltage side to the second direct voltage circuit and on an alternating voltage side to the drive motor. 
     This object and further objects, advantages and features of the present disclosure are clear from the following detailed description of exemplary embodiments of the disclosure in conjunction with the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  shows a known fuel/electric drive system, 
         FIG. 2  shows a first exemplary embodiment of the fuel/electric drive system according to the disclosure, 
         FIG. 3  shows a second exemplary embodiment of the fuel/electric drive system according to the disclosure, 
         FIG. 4  shows a third exemplary embodiment of the fuel/electric drive system according to the disclosure, 
         FIG. 5  shows a fourth exemplary embodiment of the fuel/electric drive system according to the disclosure, and 
         FIG. 6  shows a fifth exemplary embodiment of the fuel/electric drive system according to the disclosure. 
     
    
    
     The reference symbols used in the drawing and their meaning are listed together in the list of reference symbols. Basically, identical parts are provided with identical reference symbols in the figures. The described embodiments are examples of the subject matter of the disclosure and do not have a restrictive effect. 
     DETAILED DESCRIPTION 
     The fuel/electric drive system comprises an internal combustion engine and a generator which is driven by the internal combustion engine and which has a first stator winding set. Furthermore, the fuel/electric drive system comprises a first rectifier which is connected on the alternating voltage side to the first stator winding set and on the direct voltage side to a first direct voltage circuit. In addition, the fuel/electric drive system comprises a first power inverter which is connected on the direct voltage side to the first direct voltage circuit and on the alternating voltage side to a drive motor. According to the disclosure, the generator has a second stator winding set. Furthermore, a second rectifier is connected on the alternating voltage side to the second stator winding set and on the direct voltage side to a second direct voltage circuit. Furthermore, a second power inverter is connected on the direct voltage side to the second direct voltage circuit and on the alternating voltage side to the drive motor. Via the second stator winding set, the second rectifier which is connected to it and the power inverter which is connected to the second rectifier via the second direct voltage circuit, a redundant feed path for feeding the drive motor is advantageously provided so that, for example, in the event of a fault or short circuit in one of the two stator winding sets, the drive motor can advantageously be fed via the other feed path which is not subject to a fault. The drive system therefore continues to be available in the event of a fault. Accordingly, the fuel/electric drive system according to the disclosure is overall very robust. Furthermore, the internal combustion engine can be operated with a variable rotational speed and therefore advantageously in a way which is efficient in terms of fuel by means of the generator with the two stator winding sets and the downstream elements of the drive system. In addition, by virtue of the operation with a variable rotational speed, it is possible to dispense with a transmission between the internal combustion engine and generator. 
       FIG. 2  shows a first exemplary embodiment of the fuel/electric drive system according to the disclosure. In said figure, the fuel/electric drive system comprises an internal combustion engine  1  and a generator  2  which is driven by the internal combustion engine  1  and which has a first stator winding set A. The internal combustion engine  1  is embodied, for example, as a diesel engine, as a gas turbine or generally as any internal combustion engine which is known to a person skilled in the art. Furthermore, the fuel/electric drive system comprises a first rectifier  3  which is connected on the alternating voltage side to the first stator winding set A and on the direct voltage side to a first direct voltage circuit  4 . In addition, the fuel/electric drive system comprises a first power inverter  5  which is connected on the direct voltage side to the first direct voltage circuit  4  and on the alternating voltage side to a drive motor  6 . 
     According to the disclosure, the generator  1  has a second stator winding set A. Generally, each stator winding set A, B comprises e phase windings, where e≧3. In the exemplary embodiment in  FIG. 2  and in the exemplary embodiments according to  FIGS. 3 to 6  which are described below in detail, in each case two stator winding sets A, B with in each case e=3 phase windings are assumed. Furthermore, according to  FIG. 2 , a second rectifier  7  is connected on the alternating voltage side to the second stator winding set B and on the direct voltage side to a second direct voltage circuit  8 . Moreover, a second power inverter  9  is connected on the direct voltage side to the second direct voltage circuit  8  and on the alternating voltage side to the drive motor  6 . The drive motor  6  likewise generally comprises two stator winding sets, each stator winding set having a phase winding, where a≧3. In the exemplary embodiment in  FIG. 2  and in the exemplary embodiments according to  FIGS. 3 to 6  which are described below in detail, in each case two stator winding sets with in each case a=3 phase windings are assumed for the drive motor  6 . Using the second stator winding set B of the generator  2 , of the second rectifier  7  which is connected to it and of the power inverter  9  which is connected to the second rectifier  7  via the second direct voltage circuit  8 , a redundant feed path for feeding the drive motor  6  is advantageously provided so that, for example, in the event of a fault or short circuit in one of the two stator winding sets A, B, the drive motor  6  can advantageously be fed via the other feed path which is not subject to a fault. As a result, the fuel/electric drive system continues to be available in the event of a fault, i.e. the drive motor  6  can continue to be fed. Accordingly, the fuel/electric drive system according to the disclosure is very robust overall and has a high level of availability. Furthermore, the internal combustion engine  1  can be operated with a variable rotational speed and therefore advantageously in a way which is efficient in terms of fuel by means of the generator  2  with the two stator winding sets A, B and the downstream elements  3 ,  4 ,  5 ,  6  of the drive system. In addition, by virtue of the operation with a variable rotational speed it is possible to dispense with a transmission  40  which is customarily connected between the internal combustion engine  1  and the generator  2 , as is shown in the known fuel/electric drive system. 
     According to  FIG. 2 , an isolating switch  10  is connected into the connection of the first stator winding set A to the first rectifier  3 , and an isolating switch  11  is connected into the connection of the second stator winding set B to the second rectifier  7 . If, for example, a fault occurs in one of the stator winding sets A, B of the generator  2 , the rectifier  3 ,  7  which is connected to the stator winding set A, B which is subject to a fault can be disconnected easily and quickly by means of the respective isolating switch  10 ,  11 , and this rectifier  3 ,  7  and the downstream elements such as the direct voltage circuit  4 ,  8 , power inverter  5 ,  9  and drive motor  6  can be protected against damage or even destruction. Of course, the respective isolating switch  10 ,  11  also permits the respective stator winding set A, B of the generator  2  to be disconnected in the event of a fault on the part of the respective rectifier  3 ,  7 . The respective isolating switch  10 ,  11  of course also permits the corresponding stator winding set A, B to be reconnected to the respective rectifier  3 ,  7 , for example after the fault which occurs has been checked or after maintenance or repair work. 
     According to  FIG. 2 , an isolating switch  12  is connected into the connection of the first power inverter  5  to the drive motor  6  and an isolating switch  13  is also connected into the connection of the second power inverter  9  to the drive motor  6 . If, for example, a fault occurs in the drive motor  6 , the respective power inverter  5 ,  9  which is connected to the drive motor  6  can be disconnected easily and quickly by means of the respective isolating switch  12 ,  13 , and the respective power inverter  5 ,  9  and the preceding elements such as the direct voltage circuit  4 ,  8 , rectifier  3 ,  7  and generator  2  can be protected against damage or even destruction. Of course, the respective isolating switch  12 ,  13  also permits the drive motor  6  to be disconnected in the event of a fault on the part of the respective power inverter  5 ,  9 . The respective isolating switch  12 ,  13  of course also permits the drive motor  6  to be reconnected to the respective power inverter  5 ,  9 , for example after the fault which occurs has been checked or after maintenance or repair work. 
     Furthermore, the first direct voltage circuit  4  can be connected to the second direct voltage circuit  8  and disconnected from it via a connecting switch  14 . The connecting switch  14  therefore makes it possible to feed one of the direct voltage circuits  4 ,  8  by means of the respective other direct voltage circuit  4 ,  8  if, for example, the connection of the first stator winding set A with the first rectifier  3  has been disconnected by means of the isolating switch  10 , or the connection of the second stator winding set B to the second rectifier  7  has been disconnected by means of the isolating switch  11  owing to a fault as mentioned above. Accordingly, in the event of a fault, the drive motor  6  can also advantageously be fed from the first direct voltage circuit  4  by means of the first power inverter  5 , and additionally also fed from the second direct voltage circuit  8  by means of the second power inverter  9 . 
     In addition, x further power inverters  15  are generally connected on the direct voltage side to the first direct voltage circuit  4 , where x≧1, and in  FIG. 2  x=1 such further power inverters  15  are connected on the direct voltage side to the first direct voltage circuit  4 . Each of the further x power inverters  15  makes it advantageously possible to feed, for example, a further drive motor but also, for example, to feed auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. Of course, such a power inverter  15  is also designed to be capable of feeding back energy. In addition, generally y further power inverters  16  are connected on the direct voltage side to the second direct voltage circuit  8 , where y≧1, and in  FIG. 2  y=1 such further power inverters  16  are connected on the direct voltage side to the second direct voltage circuit  8 . Each of the further y power inverters  16  also advantageously makes it possible in this case to feed, for example, a further drive motor but also to feed, for example, auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. 
       FIG. 3  shows a second exemplary embodiment of the fuel/electric drive system according to the disclosure. On the basis of  FIG. 2 , the fuel/electric drive system according to  FIG. 3  generally has z further power inverters  17  which are connected on the direct voltage side to the first direct voltage circuit  4  and to the second direct voltage circuit  8 , where z≧1, and in  FIG. 3  z=1 such further power inverters  17  are connected on the direct voltage side to the first direct voltage circuit  4  and to the second direct voltage circuit  8 . As a result, each of the further z power inverters  17  can advantageously be fed from both direct voltage circuits  4 ,  8 , in which case each of the further z power inverters  17  makes it possible to feed, for example, a further drive motor but also to feed, for example, auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. Of course, such a power inverter  17  is also designed to be capable of feeding back energy. According to  FIG. 3 , an element  18  for limiting the direction of current is connected into each connection of the first direct voltage circuit  4  to one of the z further power inverters  17 , and an element  19  for limiting the direction of current is connected into each connection of the second direct voltage circuit  8  to one of the z further power inverters  17 . The respective element  18 ,  19  for limiting the direction of current serves to ensure that only a current in a defined direction of current flows from the respective direct voltage circuit  4 ,  8  to the respective power inverter  17  of the z further power inverter  17  and back again in a defined fashion. This advantageously avoids a situation in which a faulty current, caused for example by faults in the respective direct voltage circuits  4 ,  8  and/or by a fault in one of the z further power inverters  17 , can flow to the respective power inverter  17  or into the respective direct voltage circuit  4 ,  8  and damages or even destroys the respective power inverter  17  or the elements which are directly and indirectly connected to the respective direct voltage circuit  4 ,  8 . The respective element  18 , 19  for limiting the direction of current can be embodied by means of diodes according to  FIG. 3  and therefore can be implemented in a way which is very simple and space-saving. However, switching elements which can be actuated, in particular power semiconductor switches which can be actuated, are also conceivable. It is to be noted that the z further power inverters  17  and their connections on the direct voltage side which are described in detail above with reference to  FIG. 3  can also be combined with the fuel/electric drive system according to  FIG. 2  and with the fuel/electric drive systems according to  FIG. 4 ,  FIG. 5  and  FIG. 6  which are also described in detail below. 
       FIG. 4  illustrates a third exemplary embodiment of the fuel/electric drive system according to the disclosure. On the basis of  FIG. 2 , generally n further rectifiers  20  are connected on the alternating voltage side to the first stator winding set A according to  FIG. 4 , where n≧1, and in  FIG. 4  n=1 further rectifiers  20  are connected on the alternating voltage side to the first stator winding set A. In addition, according to  FIG. 4  generally m further power inverters  21  are connected to in each case one of the n rectifiers  20  via a direct voltage circuit  22  which is provided for each of the n further rectifiers  20 , where m≧1, and in  FIG. 4  m=1 further power inverters  21  are connected to in each case one of the n rectifiers  20  via a direct voltage circuit  22  which is provided for each of the n further rectifiers  20 . The first stator winding set A can therefore be used to feed, for example, not only a further drive motor but, for example, also auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. by means of the respective further power inverter  21  of the m further power inverters  21  separately from and independently of the first and second direct voltage circuit  4 ,  8 . Furthermore, according to  FIG. 4 , p further rectifiers  26  are connected on the alternating voltage side to the second stator winding set B, where p≧1, and in  FIG. 4  p=1 further rectifiers  26  are connected on the alternating voltage side to the second stator winding set B. In addition, according to  FIG. 4  generally q further power inverters  27  are connected in each case to one of the p rectifiers  26  via a direct voltage circuit  28  which is provided for each of the p further rectifiers  26 , where q≧1, and in  FIG. 4  q=1 further power inverters  27  are connected to in each case one of the p rectifiers  26  via a direct voltage circuit  28  which is provided for each of the p further rectifiers  26 . The second stator winding set B can therefore be used to feed, for example, not only a further drive motor but, for example, also auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. by means of the respective further power inverter  27  of the m further power inverters  26  separately from and independently of the first and second direct voltage circuits  4 ,  8 . According to  FIG. 4 , an isolating switch  25  is connected into each connection of the first stator winding set A to one of the n further rectifiers  20 . Furthermore, according to  FIG. 4 , an isolating switch  31  is additionally connected into each connection of the second stator winding set B to one of the p further rectifiers  26 . If, for example, a fault occurs in one of the stator winding sets A, B of the generator  2 , the further rectifier  20 ,  26  which is connected to the stator winding set A, B which is subject to a fault can be disconnected easily and quickly by means of the respective isolating switch  25 ,  31 , and this further rectifier  20 ,  26  and the downstream elements such as the direct voltage circuit  22 ,  28  and further power inverters  21 ,  27  can be protected against damage or even destruction. Of course, the respective isolating switch  25 ,  31  also permits the respective stator winding set A, B of the generator  2  to be disconnected in the event of a fault on the part of the respective further rectifier  20 ,  26 . Of course, the respective isolating switch  25 ,  31  also permits the corresponding stator winding set A, B to be reconnected to the respective further rectifier  20 ,  26 , for example after the fault which occurs has been checked or after maintenance or repair work. It is to be noted that the n further rectifiers  20  and their connections which are described above in detail with respect to  FIG. 4  and the p further rectifiers  26  and their connections which are described above in detail with respect to  FIG. 4  can also be combined with the fuel/electric drive system according to  FIG. 2 ,  FIG. 3  and with the fuel/electric drive systems according to  FIG. 5  and  FIG. 6  which are also described in detail below. 
       FIG. 5  shows a fourth exemplary embodiment of the fuel/electric drive system according to the disclosure. On the basis of  FIG. 4 , n further rectifiers  20  are connected on the alternating voltage side to the first stator winding set A according to  FIG. 5 , in a way which generally corresponds to  FIG. 4 , where n≧1, and in  FIG. 5  n=1 further rectifiers  20  are connected on the alternating voltage side to the first stator winding set A. In addition, according to  FIG. 5  generally m further power inverters  21  are connected to in each case one of the n rectifiers  20  via a direct voltage circuit  22  which is provided for each of the n further rectifiers  20 , where m≧1, and in  FIG. 5  m=1 further power inverters  21  are connected to in each case one of the n rectifiers  20  via a direct voltage circuit  22  which is provided for each of the n further rectifiers  20 . The first stator winding set A can therefore be used to feed, for example, not only a further drive motor but, for example, also auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. separately from and independently of the first and second direct voltage circuits  4 ,  8  by means of the respective further power inverter  21  of the m further power inverters  21 . According to  FIG. 5 , an isolating switch  25  is connected into each connection of the first stator winding set A to one of the n further rectifiers  20 , in which context the statements relating to  FIG. 4  should be referred to with regard to the method of functioning and advantages. Furthermore, according to  FIG. 5  generally r further rectifiers  23  are connected on the alternating voltage side to the second stator winding set B, where r≧1 and n≧r, and in  FIG. 5  r=1 further rectifiers  23  are connected on the alternating voltage side to the second stator winding set B. In addition, according to  FIG. 5 , each of the r further rectifiers  23  is connected on the direct voltage side to in each case one of the direct voltage circuits  22  which are provided for the n further rectifiers  20 . In the event of a fault, for example in the first stator winding set A of the generator  2 , the respective further rectifier  20  is disconnected by means of the isolating switch  25 , in which case the direct voltage circuit  22  which is connected to the further disconnected rectifier  20  can advantageously be fed by means of the further rectifier  23  thereby making it possible to feed not only a further drive motor but, for example, also auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. from this direct voltage circuit  22  by means of the further power inverter  21 , even in such a case of a fault. In addition, an isolating switch  24 , which advantageously permits the further respective rectifier  23  to be disconnected and reconnected to the second stator winding set B of the generator  2 , is connected into each connection of the second stator winding set B to one of the r further rectifiers  23 . It is to be noted that the r further rectifiers  23  and their connections which are described in detail above with reference to  FIG. 5  can also be combined with the fuel/electric drive system according to  FIG. 2 ,  FIG. 3  and  FIG. 4  as well as with the fuel/electric drive system according to  FIG. 6  which is described in detail below. 
       FIG. 6  shows a fifth exemplary embodiment of the fuel/electric drive system according to the disclosure. On the basis of  FIG. 4 , p further rectifiers  26  are connected on the alternating voltage side to the second stator winding set B according to  FIG. 6  in a way which generally corresponds to  FIG. 4 , where p≧1, and in  FIG. 4  p=1 further rectifiers  26  are connected on the alternating voltage side to the second stator winding set B. In addition, according to  FIG. 6 , q further power inverters  27  are generally connected in each case to one of the p rectifiers  26  via a direct voltage circuit  28  which is provided for each of the p further rectifiers  26 , where q≧1, and in  FIG. 4  q=1 further power inverters  27  are connected to in each case one of the p rectifiers  26  via a direct voltage circuit  28  which is provided for each of the p further rectifiers  26 . The second stator winding set B can therefore be used to feed, for example, not only a further drive motor but, for example, also auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. separately from and independently of the first and second direct voltage circuits  4 ,  8  by means of the respective further power inverter  27  of the m further power inverters  27 . According to  FIG. 6 , an isolating switch  31  is connected into each connection of the second stator winding set B to one of the p further rectifiers  26 , and in this context the statements relating to  FIG. 4  should be referred to with regard to the method of functioning and advantages. Furthermore, according to  FIG. 5  generally v further rectifiers  29  are connected on the alternating voltage side to the first stator winding set A, where v≧1 and p≧v, and in  FIG. 6  v=1 further rectifiers  29  are connected on the alternating voltage side to the first stator winding set A. In addition, according to  FIG. 6  each of the v further rectifiers  29  is connected on the direct voltage side to in each case one of the direct voltage circuits  28  which are provided for the p further rectifiers  26 . In the event of a fault in, for example, the second stator winding set B of the generator  2 , the respective further rectifier  26  is disconnected by means of the isolating switch  31 , in which case the direct voltage circuit  28  which is connected to the further disconnected rectifier  26  can advantageously be fed by means of the further rectifier  29 , therefore making it possible to feed a further drive motor and, for example, also to feed auxiliary operating devices such as fans, air-conditioning systems, actuator motors etc. from this direct voltage circuit  28  by means of the further power inverter  27 , even in such a case of a fault. In addition, an isolating switch  30 , which advantageously permits the respective further rectifier  29  to be disconnected and reconnected to the first stator winding set A of the generator  2 , is connected into each connection of the first stator winding set A to one of the v further rectifiers  29 . It is to be noted that the v further rectifiers  29  and their connections which are described in detail above with reference to  FIG. 6  can also be combined with the fuel/electric drive system according to  FIG. 2 ,  FIG. 3 ,  FIG. 4  and  FIG. 5 . 
     It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Internal combustion engine 
           2  Generator 
           3  First rectifier 
           4  First direct voltage circuit 
           5  First power inverter 
           6  Drive motor 
           7  Second rectifier 
           8  Second direct voltage circuit 
           9  Second power inverter 
           10 ,  11 ,  12  Isolating switch 
           13 ,  24 ,  25   
           30 ,  31   
           14  Connecting switch 
           15  x further power inverters, where x≧1 
           16  y further power inverters, where y≧1 
           17  z further power inverters, where z≧1 
           18 ,  19  Element for limiting the direction of current 
           20  n further rectifiers, where n≧1 
           21  m further power inverters, where m≧1 
           22  Direct voltage circuit of each of the n further rectifiers  20   
           23  r further rectifiers, where r≧1 
           26  p further rectifiers, where p≧1 
           27  q further power inverters, where q≧1 
           28  Direct voltage circuit of each of the p further rectifiers  26   
           29  v further rectifiers, where v≧1 
           40  Transmission 
         A, B Stator winding sets of the generator