Abstract:
The proposed electric machine with integrated power electronics is modularly constructed, it being possibly prefabricated and separately to install the parts stator carrier ( 2 ), control ( 10 ) for the power semiconductor DC+ ( 4 ), DC bars ( 5 ), power semiconductor ( 8 ), cooling duct ( 12 ) for power electronics and electric machine, stator ( 1 ) and stator winding ( 3 ).

Description:
[0001]     This application claims priority from German Application Serial No. 10 2005 032 191.7 filed Jul. 9, 2005.  
       FIELD OF THE INVENTION  
       [0002]     This invention concerns an electric machine with integrated power electronics. The invention further relates to a method for producing the bond of the DC bars with the DC contact surfaces of the power semiconductor of the electronics of the electric machine, particularly of an inventive electric machine.  
       BACKGROUND OF THE INVENTION  
       [0003]     Electric machines of this kind have been used in the prior art, among others in crankshaft-starter generators in hybrid vehicles where, in the power semiconductor is disposed, distributed on the periphery of the electric machine so as to make the connecting line to the electric machine as short as possible. Hybrid vehicles essentially have an internal combustion engine as a prime mover and they have, in addition, electric motors which make utilization of brake energy and driving with low emission possible.  
         [0004]     From the Applicant&#39;s DE 199 23 315 A1 is known a driving system for a motor vehicle driven by a prime mover and having a transmission unit and at least one electric machine operable as motor and/or generator. The electric machine comprises at least one stator and one rotor with active parts which, having no housing of their own, are situated within a housing of the prime mover and/or of the transmission unit axially symmetrically and/or co-axially relative to an input chain shaft or a rotating part disposed parallel therewith and form with parts of the prime mover and/or of the transmission unit, a structural unit.  
         [0005]     From DE 44 04 791 C1 is also known a structural unit consisting of an internal combustion engine comprising one crankshaft and one electric generator/motor of which the generator housing is firmly connected with the motor housing and the rotor is co-axially, non-rotatably connected with the crankshaft. Here an elastically deformable torque-transmitting disc is provided which is firmly flange mounted on the output side of the crankshaft and firmly connected with the rotor on the peripheral side. The rotor is also rotatably supported on the generator housing.  
         [0006]     In the electric machines with integrated power electronics known from the prior art, the individual parts are interconnected by way of connecting devices, preferably by way of screws. Screws are needed, for example, for fastening the semiconductor module and the DC bars. This results in great expenditure of time for serial production due to the expensive assembly and the large number of manipulations, the same as in an increased additional installation space needed for the connection technology.  
         [0007]     The necessary intermediate circuit capacity determined by the system has to be separately installed and adequately integrated which disadvantageously further increases the installation space required.  
         [0008]     The problem on which this invention is based is to outline an electric machine with integrated power electronics in which the mentioned disadvantages of the electric machines with integrated power electronics known from the prior art can be overcome. The assemblage is to be specially simplified and the needed installation space minimized. Also to be outlined is a method for producing the bond of the DC bars with the DC contact surfaces of the power semiconductor of the power electronics, especially in an inventive electric machine.  
       SUMMARY OF THE INVENTION  
       [0009]     A modularly constructed electric machine with integrated power electronics is accordingly proposed in which the parts stator carrier, control for the power semiconductor, positive DC bar, negative DC bar, power semiconductor, cooling duct for power electronics and electric machine, stator and stator winding are prefabricated and then separately installed. This modular design is made possible by the axially symmetrical shape of aid parts.  
         [0010]     It is further proposed to construct the positive and negative DC bars so that radially observed they are disposed essentially superimposed, and axially observed they are essentially disposed parallel with each other. It is possible to situate an insulator between both bars. The side of both DC bars facing the insulator is roughened by suitable steps, such as by etching, whereby a large contact surface results. In this manner, the required intermediate circuit capacitor determined by the system is integrated in the power electronics.  
         [0011]     With the scope of a specially advantageous development of the invention, it is provided that both DC bars and the insulator be constructed so that a snap-on connection results. In this way, the individual parts need only, in addition, to be moved superimposed, in the assembly, which results in the advantage that added fastening devices, such as screws, are eliminated.  
         [0012]     The DC bars are bonded with the DC contact surfaces of the power semiconductor by the fact that when producing the power semiconductor a soldered layer or a layer of another adequate connecting medium is applied to the contact surfaces. After assemblage, it is possible to supply the electric machine and the power electronics with current for the first time. Due to the initially high ohmic resistance on the contact surfaces, heat generates by which the connection is produced. This leads to the lowering of the ohmic resistance on the contact power so that the system is prepared for regular operation. During the first current supply, the ohmic resistance (online) can optionally be measured in order to implement a quality control without added expense.  
         [0013]     According to the invention, the end of the stator winding is designed as link which, after introducing the power electronic module, is bent up and preferably soldered with the AC contact surface during the previously described operation of the first supply of current.  
         [0014]     Within the scope of another embodiment of the invention, the bond between the DC bars and the power semiconductor can also be produced by extruding. For the purpose, the semiconductor module and the DC bars can be constructed conically adapted to each other. By showing the individual parts, the fit into each other spans and is fixed by the snap-on connection described. The electric connection is produced by the surface pressure on the contact points. This procedure has the advantage that the process of supplying current for welding the connections is eliminated. In this embodiment, one more snap-on connection is needed between a DC bar and the power semiconductor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0016]      FIG. 1  is a diagrammatic representation of an electric machine with integrated power electronics according to the prior art;  
         [0017]      FIG. 2  is a diagrammatic representation of an electric machine with integrated power electronics according to a first embodiment of the instant invention, and  
         [0018]      FIG. 3  is a diagrammatic representation of an electric machine with integrated power electronics according to a second embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     In  FIG. 1  is shown an electric machine with integrated power electronics as in the prior art. It comprises one stator  1 , one stator carrier  2 , one stator winding  3  and one semiconductor module fastened by way of screws  11  and having one positive DC bar  4 , one negative DC bar  5 , respectively connected with a power semiconductor  8  via one positive DC bond  6  and one negative DC bond  7 . The DC bars  4 ,  5  are secured to the power semiconductor  8  via screws  9 . Axially observed, a control  10  for the power semiconductor  9  is provided between the DC bars  4 ,  5 . Radially observed is one cooling duct  12 , provided between the stator  1  and the power semiconductor  8  for cooling the electric machine and the power electronics. In  FIG. 1 , an AC bond between the stator winding and the semiconductor module is designated with the reference numeral  13 .  
         [0020]     In the construction according to  FIG. 1 , connecting devices such as screws are needed for interconnecting the individual parts which results in considerable expenditure of time for serial production and in an increased additional installation space. These disadvantages are overcome by the inventive electric machine with integrated power electronics.  
         [0021]     A first embodiment of the invention is shown in  FIG. 2 . The parts stator carrier  2 , control for the power semiconductor  10 , positive DC bar  4 , negative DC bar  5 , power semiconductor  8 , cooling duct  12  for power electronics and electric machine, stator  1  and stator winding  3  are prefabricated and separately installed.  
         [0022]     As is to be understood from  FIG. 2 , the positive and negative DC bars  4 ,  5 , radially observed, are disposed essentially superimposed and axially observed are disposed essentially parallel with each other. It is possible to situate an insulator  14  between both bars, whereby the necessary intermediate circular capacitor subject to the system is integrated in the power electronics.  
         [0023]     According to the invention, the side of both DC bars  4 ,  5 , facing the insulator  14 , is roughened in order to implement a large contact surface.  
         [0024]     An end  16  of the stator winding  3  is preferably designed as a link which, after the power electronic module is inserted, is bent up and soldered with the power semiconductor  8 . Combined with a plug connection  15 , it is possible to fix the semiconductor module between the power semiconductor  8  and the stator carrier  2 .  
         [0025]     Both DC bars  4 ,  5  and the insulator  14  are advantageously designed so that a snap-on connection results.  
         [0026]     According to the invention, the bond  6  or  7  and the respective DC bars  4  and  5  with the DC contact surfaces of the power semiconductor  8  can be produced by applying on the contact surfaces while producing the semiconductor  8  a soldered layer or a layer of any other suitable connection medium, the electric machine and the power electronics being supplied for the first time with current after the assemblage. By the heat generated on the contact surfaces by the initially high ohmic resistance, the connection or bond is produced, the ohmic resistance on the contact point then lowering so that the system is prepared for regular operation. During the first current supply, it is of particular advantage that the ohmic resistance (online) be measured in order to implement a quality control without added cost.  
         [0027]     Within the scope of an advantageous development of the invention, which is the object of  FIG. 3 , the bond between the DC bars  4 ,  5  and the power semiconductor  8  can be produced by extrusion. For the purpose, according to a specially advantageous embodiment of the invention, the semiconductor module and the DC bars  4 ,  5  can be conically configured adapting to each other so that by slipping on the individual parts the adaptation into each other is braced and fixed with the snap-on connection above described. The electric connection is created by surface pressure on the contact points. In this embodiment, one other snap-on connection  17  is needed between the DC bar (it is the negative DC bar in the Figure) and the power semiconductor  8 .  
         [0028]     Any structural design, especially any spatial arrangement of the parts of the inventive electric machine with integrated power electronics and relative to each other and, insofar as technically significant, falls under the scope of protection of the instant claims without affecting the operation of the electric machine, even if those designs have not beem explicitly shown in the Figures or in the description.  
                                         Reference numerals                                1   stator       2   stator carrier       3   stator winding       4   positive DC bar       5   negative DC bar       6   positive DC bond       7   negative DC bond       8   power semiconductor       9   screw       10   control for the power semiconductor       11   screw       12   cooling duct       13   AC bond between stator winding           and semiconductor module       14   insulator       15   plug connection between stator           carrier &amp; semiconductor module       16   end of the stator winding       17   snap-on connection