Abstract:
Electric drive device for an electric power steering system that includes an electric motor with a motor case, and a motor shaft with a drive end, an electronic control unit that controls the drive of the motor, According to one embodiment the electronic control unit includes a power board and a heat sink. A connector coupled to a side of the electric drive device is at least partially maintained in its position with the use of one or more projections projecting from a first area of the connector that reside within one or more corresponding housings located in a peripheral region of the heatsink.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application relates to and claims the benefit and priority to International Application No. PCT/EP2014/064058, filed Jul. 2, 2014, which claims the benefit and priority to European Application No. 13382281.7, filed Jul. 8, 2013. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is related to an electric drive device for an electric power steering system of automotive vehicles. 
       BACKGROUND 
       [0003]    Electric power steering (EPS) systems of automotive vehicles, which assist in moving the steering wheel of automotive vehicles, are known in the state of the art. The assistance in moving the steering wheel consists of the EPS system delivering mechanical torque to the steering column of the automotive vehicle. In order to be able to generate the delivery torque, the EPS system comprises an electric drive device, said device comprising an electric motor generating mechanical torque. The electric motor is usually a three-phase alternating current (AC) motor, but the electric drive device is powered with direct current DC from the vehicle, so it is necessary to convert said direct current into three-phase alternating current, and it is furthermore necessary to control the drive of the electric motor, so the electric drive device needs an electronic control unit close to the electric motor. 
         [0004]    EP2549627 A1 discloses an electric drive device for an EPS system, comprising an electric motor with a motor case, a stator arranged inside the motor case providing a plurality of phases, a rotor arranged rotatably in relation to the stator, and a motor shaft that rotates together with the rotor with a drive end of the output torque of the motor projecting from the motor case. The device also comprises an electronic control unit, after the motor, controlling the drive of the motor, comprising a power board supplying current to the motor, and a control board electrically connected to the power board controlling the drive of the motor through the power board, and a heat sink absorbing and dissipating the heat generated by the power board. The heat sink, the power board and the control board are arranged after the motor in the mentioned order. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    According to one implementation an electric drive device is provided that comprises an electric motor with a motor case, a stator arranged inside the motor case providing a plurality of phases, a rotor arranged rotatably in relation to the stator, and a motor shaft that rotates together with the rotor with a drive end of the output torque of the motor projecting from the motor case. The device also comprises an electronic control unit controlling the drive of the motor, the electronic control unit comprising a power board supplying current to the motor, and a control board electrically connected to the power board controlling the drive of the motor through the power board, and a heat sink absorbing and dissipating the heat generated by the power board. The heat sink, the power board and the control board are arranged after the motor in the mentioned order. In said electric drive device, the power board covers the cross section of the motor case. 
         [0006]    Since the power board is arranged so as to cover the cross section of the motor case, it allows arranging the distinct elements of said power board such that they are better distributed in a single part and facing the heat sink. Therefore on one hand, the number of parts of the electric drive device is reduced because the power board covers a larger surface in a single part. On the other hand, heat dissipation, and therefore thermal efficiency, of the electric drive device improves, because the motor, which generates heat, discharges said heat perimetrally towards the motor case, and the heat arriving to the heat sink is mainly from the power board located on said heat sink. A more compact design of the electric drive device is further obtained because by covering the cross section of the motor case as the elements of the power board are arranged in said cross section a smaller power board is obtained. 
         [0007]    These and other advantages and features will become evident in view of the drawings and the detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a perspective view an electric drive device according to one embodiment. 
           [0009]      FIG. 2  shows an elevational view of the device of  FIG. 1 . 
           [0010]      FIG. 3  shows a longitudinal section view according to line III-III of the device of  FIG. 2 . 
           [0011]      FIG. 4  shows an exploded view of the main parts of the device of  FIG. 1 . 
           [0012]      FIG. 5  shows a perspective view of the outer side of the second part of an embodiment of the heat sink of the device of  FIG. 1 . 
           [0013]      FIG. 6  shows a longitudinal section view of the device of  FIG. 1  with a second embodiment of the heat sink. 
           [0014]      FIG. 7  shows an exploded view of the main parts of the device of  FIG. 6 . 
           [0015]      FIG. 8  shows a detailed view of the heat sink of the device of  FIG. 6 . 
           [0016]      FIG. 9  shows a perspective view of the upper side of an embodiment of the power board of the device of  FIG. 1 . 
           [0017]      FIG. 10  shows a perspective view of the lower side of the embodiment of the power board of  FIG. 9 . 
           [0018]      FIG. 11  shows a perspective view of the upper side of an embodiment of the control board of the device of  FIG. 1 . 
           [0019]      FIG. 12  shows a perspective view of the lower side of the embodiment of the control board of  FIG. 11 . 
           [0020]      FIG. 13  shows a front perspective view of an embodiment of the connector of the device of  FIG. 1 . 
           [0021]      FIG. 14  shows a rear perspective view of the embodiment of the connector of  FIG. 13 . 
           [0022]      FIG. 15  shows a front perspective view of a second embodiment of the connector of the device of  FIG. 1  without ground connections. 
           [0023]      FIG. 16  shows a rear perspective view of the embodiment of the connector of  FIG. 15 . 
           [0024]      FIG. 17  shows a block diagram showing the communications of the main parts of the power board and the control board of the device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows a perspective view of an electric drive device according to one embodiment,  FIG. 2  shows an elevational view of the device of  FIG. 1 ,  FIG. 3  shows a longitudinal section view according to line III-III of the device of  FIG. 2 ,  FIG. 4  shows an exploded view of the main parts of the device of  FIG. 1 , and  FIG. 5  shows a perspective view of the outer side of the second part of an embodiment of the heat sink of the device of  FIG. 1 . 
         [0026]    The electric drive device  100  is applied to an electric power steering (EPS) system of an automotive vehicle. Said device  100  comprises an electric motor  1  arranged inside a motor case  2  made of aluminum. The motor  1  is the power supply source of the EPS system, said motor  1  in this embodiment being a three-phase brushless alternating current (AC) motor. Said motor  1  basically comprises a stator  3  arranged inside the motor case  2 , a rotor  5  arranged rotatably in relation to the stator  3  therein, and a motor shaft  6  that rotates together with the rotor  5  in an integral manner, said motor shaft  6  comprising a drive end  7  of the output torque of the motor  1  projecting from the motor case  2 . 
         [0027]    The rotor  5  is a permanent magnet-type rotor with a plurality of poles, and the stator  3  includes a plurality of projecting poles arranged facing the permanent magnet of the rotor  5  around same. The stator  3  comprises a plurality of windings arranged around the poles of the stator  3 , and three phases  4  (U, V, W) with terminals projecting from the motor case  2  being connected to these windings. 
         [0028]    In this embodiment of the device  100 , the motor case  2  has a substantially cylindrical shape. It comprises a side wall  102  and an end  105  with a lid  106  formed in the actual motor case  2 , where the drive end  7  of the motor shaft  6  projects. The device  100  is used by an EPS system to provide assistance in moving the steering wheel of an automotive vehicle, said assistance consisting of the EPS system delivering mechanical torque from the steering column of the automotive vehicle. In order to generate the delivery torque, the EPS system comprising the electric drive device  100  has an electric motor  1 . This motor  1  generates the mechanical torque and delivers it through the drive end  7  of the motor shaft  6 . This drive end  7  is coupled to a reduction gear of the EPS system (not shown in the drawings), which in turn is connected to the steering column of the vehicle. Therefore, when the vehicle driver operates the steering wheel a mechanical torque is generated in the steering column that is detected by a torque sensor (not shown in the drawings). The detected torque is sent as a signal to the device  100 , which generates a mechanical torque by means of the electric motor  1 , said torque being transmitted to the reduction gear of the EPS system, and this EPS system transmits it to the steering column of the vehicle, assisting the driver in moving the steering wheel. 
         [0029]    In order to perform such operations in a controlled manner, the device  100  also comprises an electronic control unit  10  controlling the drive of the motor  1  with the electric current supply. The electronic control unit  10  comprises a power board  20  with semiconductor switching elements  23 ,  25 ,  27  supplying current to drive the motor  1 , and a control board  70  electrically connected to the power board  20  controlling the drive of the motor  1  through the power board  20 . The device  100  also comprises a heat sink  40 ,  40 ′ made of highly thermally conductive aluminum, absorbing and dissipating the heat generated mainly by the power board  20  through the semiconductor switching elements  23 ,  25 ,  27 . Furthermore, the electric drive device  100  comprises a cover  50  which covers the electronic control unit  10  and closes it at one end  53  against an end  101  of the motor case  2 . The assembly of the device  100  is therefore a compact unit formed by the motor case  2  and the cover  50 , the motor  1 , the heat sink  40 ,  40 ′, the power board  20  and the control board  70  being arranged in the mentioned order with respect to the drive end  7  of the motor shaft  6 . The power board  20 , which is located after the heat sink  40 ,  40 ′, covers all or almost all of the cross section of the motor case  2 . In document EP2549627 A1, the power board containing the semiconductor switching elements only partially covers the cross section of the motor. Having the power board  20  cover all or almost all of the cross section of the motor case  2  allows arranging the distinct elements of said power board such that they are better distributed in a single part and facing the heat sink. 
         [0030]    In this embodiment, the heat sink  40 ,  40 ′ is a substantially cylindrical part acting as a cover of the motor case  2  at the end  101 , and therefore is another element of said case  2 . In this embodiment of the device  100 , the heat sink  40 ;  40 ′ comprises a substantially planar outer side  47 ,  49  distributed in a substantially uniform manner, facing and adjacent to the power board  20 . The heat sink  40 ,  40 ′ is arranged at the end  101  of said motor case  2 , on the side opposite the lid  106  of the case  2 , and thus closes the cylindrical shape of the motor case  2 . The heat sink  40 ;  40 ′ acting as closure lid of the motor case  2  comprises an inner side  46 ;  64  that is located inside the motor case  2 . Said heat sink  40 ;  40 ′ does not project or only slightly projects from the motor case  2 . 
         [0031]    A position end  8  of the motor shaft  6 , which is opposite the drive end  7  of said motor shaft  6 , and therefore below the inner side  46 ;  64  of the heat sink  40 ;  40 ′, is located at the end  101  of the motor case  2  and inside the motor case  2 . 
         [0032]      FIG. 6  shows a longitudinal section view of the device  100  of  FIG. 1  with a second embodiment of the heat sink  40 ,  FIG. 7  shows an exploded view of the main parts of the device  100  of  FIG. 6 , and  FIG. 8  shows a detailed view of the heat sink  40  of the device of  FIG. 6 . In this embodiment, the heat sink  40  has a substantially cylindrical shape comprises two parts. A first part  48  is supported in the motor case  2 , the inner side  46  of which comprises support means  42 . The support means  42  comprises a housing  43  arranged substantially in the center of the first part  48 , the housing  43  being open towards the outside of the motor case  2 , and wherein a bearing  110  supporting the position end  8  of the motor shaft  6  is fitted. A second part  45  of the heat sink  40  is arranged on the first part  48 , covering the housing  43 , and has a through hole  41  in the center having a diameter that is smaller than the opening of the housing  43 . The heat sink  40  thus comprises the outer side  47 , which is the free outer surface of the first part  48 . The first part  48  is made of a highly thermally conductive material, such as aluminum for example, and the second part  45  is a metal part made of pressed steel that has been subjected to anti-corrosion treatment, such as cataphoresis. 
         [0033]    The embodiment of the heat sink  40 ′ of  FIGS. 3, 4 and 5  shows how said heat sink  40 ′ also has a substantially cylindrical shape and comprises two parts. A first part  68  is supported in the motor case  2 , the inner side  64  of which comprises support means  62 . The support means  62  comprises a housing  63  arranged substantially in the center of the first part  68 , the housing  63  being open towards the outside of the motor case  2 , and wherein a bearing  110  supporting the position end  8  of the motor shaft  6  is fitted. A second part  65  of the heat sink  40  is arranged on the first part  68 , covering the entire surface of the first part  68 , and covering the housing  63 , and has a through hole  61  in the center having a diameter that is smaller than the opening of the housing  63 . The heat sink  40 ′ thus comprises the outer side  49 , which is the free outer surface of the second part  65 . Both the first part  68  and the second part  65  are made of a highly thermally conductive material, such as aluminum. 
         [0034]    In both embodiments of the heat sink  40 ;  40 ′, the drive end  7  of the motor shaft  6  is housed in another bearing arranged in the support means of the lid  106  of the motor case  2 . The bearing  110  is housed in the housing  43 ;  63  from the outside of the motor case  2  and after the first part  48 ;  68  is assembled in said motor case  2 . The heat sink  40 ;  40 ′ comprises a second part  45 ;  65  which covers the hole of the housing  43 ;  63 , demarcating a hole  41 ;  61 , having a smaller diameter than the hole of the housing  43 ;  63 , preventing accessibility to the housing  43 ;  63 , and thus completing the dissipation surface of the power board  20 . The bearing  110  is thus assembled in the housing  43 ;  63  of the heat sink  40 ;  40 ′ from the outside, and next the second part  45 ;  65  is assembled in the heat sink  40 ;  40 ′. Therefore, when the motor shaft  6  is assembled, the position end  8  is located inside the housing  43 ;  63  of the heat sink  40 ;  40 ′ and is substantially flush with the outer side  47 ;  49  of the heat sink  40 ;  40 ′. The position end  8  of the motor shaft  6  comprises a magnet  9 , and the power board  20  comprises a magnetic sensor  30  on a lower side  21  facing the heat sink  40 ;  40 ′ and substantially in the center, the magnetic sensor  30  facing the magnet  9  through the through hole  41 ;  61 . 
         [0035]    Once the heat sink  40 ;  40 ′ is assembled in the motor case  2 , next the power board  20  and the control board  70  are assembled, being arranged in the mentioned order in a substantially parallel manner, thereby obtaining a more compact structure of the device  100 , taking up less space in the length thereof. 
         [0036]      FIG. 9  shows a perspective view of the upper side  31  of an embodiment of the power board  20  of the device  100  of  FIG. 1 , and  FIG. 10  shows a perspective view of the lower side  21  of the embodiment of the power board  20  of  FIG. 9 . Since the power board  20  covers virtually the entire cross section of the motor case  2 , and since it is facing and adjacent to the heat sink  40 ;  40 ′, it allows arranging the different semiconductor switching elements, filtering elements and measuring elements on a larger surface than in power boards of the state of the art, and it therefore allows distributing all the elements uniformly and in a smaller volume. 
         [0037]    The power board  20  is a printed circuit board (PCB) formed on an insulating base preferably made of glass fiber, such as an FR material comprising four or six layers for example, and is screwed to the heat sink  40 ;  40 ′, the power board  20  and the heat sink  40 ;  40 ′ being located very close to one another at a distance between about  0 . 5  mm and about  2 . 5  mm. Semiconductor switching elements  23 ,  25 ,  27  supplying electric current to the motor  1  from the outside are assembled on the lower side  21  of the power board  20 , facing the heat sink  40 ;  40 ′, and they are located at the closest distance with respect to the heat sink  40 ;  40 ′. When the power board  20  is assembled on the heat sink  40 ;  40 ′, the semiconductor switching elements  23 ,  25 ,  27  rest on a support surface  22  of the outer side  47 ;  49  of the heat sink  40 ;  40 ′. Said support surface  22  is a surface made from an electrically insulating and highly thermally conductive material, and it can be an elastic pad or be applied as an adhesive paste on the outer side  47 ,  49 , attached to the heat sink  40 ;  40 ′. Thus, without electrical interferences, the semiconductor switching elements  23 ,  25 ,  27  transmit the heat generated to the heat sink  40 ;  40 ′ through the support surface  22 . Three shunts  29  are also assembled on the lower side  21  of the power board  20 , there being one for each of the phases  4  (U, V, W), said shunts being a resistive load through which electric current is shunted. Since the resistive load of the shunts  29  is known with precision, said shunts  29  are used for determining the intensity of the electric current flowing through this load and therefore for measuring the electric current in the phases  4  (U, V, W) of the motor  1 . 
         [0038]    In this embodiment, the semiconductor switching elements are two semiconductor switching elements  23  for each of the phases  4  (U, V, W) of an inverter  24  forming a circuit which allows converting input direct current DC into three-phase alternating current AC. Said semiconductor switching elements  23  power the motor  1 , being connected with the terminals of the phases  4  projecting from the motor case  2  through the heat sink  40 ;  40 ′ through the through holes of said heat sink  40 ;  40 ′, the semiconductor switching elements  23  being arranged directly on the terminals of the phases  4 . A semiconductor switching element  25  for each of the phases  4  (U, V, W) of three phase relays  26  of the motor  1 , which allow protecting the motor  1  of the current supply when adverse conditions are present, and also two semiconductor switching elements  27  of two power supply relays  28  supplied by an external power source V, which is the battery of the vehicle, and supplies direct current DC. Said power supply relays  28  protect the motor  1  and components of the circuit of the inverter  24  when disconnections, short circuits, excessive temperatures or voltage surges occur. 
         [0039]    The power board  20  also comprises on the side  21  facing the heat sink  40 ;  40 ′ a temperature sensor ST arranged close to the semiconductor switching elements  23  of the inverter  24  and the semiconductor switching elements  25  of the phase relays  26  of the motor  1 , since they are the most important heat generators and therefore where the temperature can be the highest. If the temperature sensor ST detects that the temperature exceeds a defined threshold temperature, it sends a signal that is picked up by a microprocessor  73  arranged in the control board  70  controlling the drive of the motor  1 . This microprocessor  73  switches to protection mode and first reduces the mechanical torque generated by the motor  1 , reducing the intensity of the electric current supplied by the motor  1 , thus reducing the level of assistance in moving the steering wheel of the vehicle. If the temperature does not stabilize, it can end up completely shutting down the movement assistance to the steering wheel of the vehicle. 
         [0040]    The phase relays  26  of the motor  1  and the power supply relays  28  are solid-state relays. Solid-state relays have a long service life and are more reliable than mechanical relays when exposed to blows and vibrations. They are smaller in size, require less control power and have very short response times. The loads are switched without bouncing and switching noise is not generated. Neighboring components are not disrupted during switching due to the electromagnetic radiation usually generated by the coils or sparks of mechanical relays. The semiconductor switching elements  25  of the phase relays  26 , the semiconductor switching elements  27  of the power supply relays  28 , and the semiconductor switching elements  23  of the inverter  24  are planar MOSFET transistors, which allows them to take up minimal space between the power board  20  and the heat sink  40 ;  40 ′. These transistors have a cut-off temperature of between about 105° C. and about 110° C. 
         [0041]    The power board  20  has a magnetic sensor  30  on the side  21  facing the heat sink  40 ;  40 ′, and substantially in the center, said sensor being a Hall effect position sensor. This sensor uses the Hall effect to determine a position. If current flows through a Hall sensor and approaches a magnetic field flowing vertically with respect to the sensor, then the sensor creates an output voltage proportional to the product of the strength of the magnetic field and of the current. The position end  8  of the motor shaft  6  has a magnet  9 , which in this embodiment is a two-pole permanent neodymium magnet enclosed in a plastic part and generating a magnetic field. This magnetic field generated by the magnet  9  is sensed by the magnetic sensor  30 , said sensor  30  generating a voltage which is sent as a signal corresponding to a direction of the generated magnetic field. This signal is sent to the microprocessor  73 , such that the electronic control unit  10  knows the position of the motor shaft  6  at all times, and thus knows the position of the poles of the permanent magnet of the rotor  5 . Therefore, and according to the situation of the vehicle, i.e., stopped or moving, and its speed, the microprocessor  73  can decide how to drive the motor  1  of the device  100 . Since the magnet  9  is arranged in the position end  8  of the motor shaft  6 , and since the magnetic sensor  30  is arranged in the power board  20 , which face one another through the through hole  41 ;  61 , and said power board  20  and the heat sink  40 ;  40 ′ being very close, a shorter motor shaft  6  is obtained, and this contributes to a more compact design of the device  100 . 
         [0042]    The power board  20  comprises an upper side  31  facing the control board  70 , a choke coil  32  being assembled on said side  31 . This choke coil  32 , which is fundamentally configured by two windings on a ferrite, allows protecting electronic equipment against high frequency disturbances, particularly by dissipating and dispersing high frequency currents. In the circuit of the electronic control unit  10 , the choke coil  32  is electrically connected between the external power source V and the power supply relays  28 . A power filter  33  comprising a coil  34  and two capacitors  35  is also assembled on the side  31  of the power board  20 . This power filter  33  allows blocking emissions, suppressing noises generated outside the device  100  and inside the device  100 , such as noises generated by the motor  1  for example. The power filter  33  is electrically connected between the power supply relays  28  and the inverter  24 . A series of drive circuits for driving circuits with electronic components are also assembled on the side  31  of the power board  20 . It therefore comprises a drive circuit  36  of the inverter  24 , a drive circuit  37  of the phase relays  26  of the motor  1 , and a drive circuit  38  of the power supply relays  28 . A connector  79   a  which allows connecting the power board  20  and the control board  70 , which allows sending signals, is also assembled on said upper side  31  of the power board  20 . 
         [0043]    To enable assembling the control board  70  in parallel and after the power board  20 , and to prevent the components assembled on the side  31  of said power board  20  from physically interfering with the components of a lower side  72  of the control board  70 , the power board  20  and the control board  70  are spaced by three spacers  71 . 
         [0044]      FIG. 11  shows a perspective view of the upper side  78  of an embodiment of the control board  70  of the device  100  of  FIG. 1 , and  FIG. 12  shows a perspective view of the lower side  72  of the embodiment of the control board  70  of  FIG. 11 . The control board  70  is a printed circuit board (PCB) formed on an insulating base which, like the power board  20 , is preferably made of glass fiber, both boards  20  and  70  being spaced by means of spacers  71 . At least one microprocessor  73  receiving signals from the different sensors of the EPS system, controlling communication with the vehicle, performing all calculations, sending signals to the inverter  24  and to the power supply relays  28  and to the phase relays  26 , and managing the status of the EPS system is assembled on the upper side  78  of the control board  70 , opposite the cover  50  of the device  100 . The upper side  78  of the control board  70  also comprises a supervision device  74  for supervising SBC communications with security functions, such as controlling power supply relays  28  for example, and for controlling consumption, performing the functions of supervising and communicating with the vehicle. A power source  75 , which is connected with the external power source V and powers at least the microprocessor  73 , the torque sensor which is located in the steering column of the vehicle, and a micro re-initializer R receiving signals from the supervision device  74  and sending signals to the microprocessor  73 , is also assembled on said upper side  78 . A connector  79   b  which allows connecting with the connector  79   a  of the upper side  31  of the power board  20 , which allows sending signals between both boards, is also assembled on the lower side  72  of the control board  70 . 
         [0045]      FIG. 13  shows a front perspective view of an embodiment of the connector of the device of  FIG. 1 , and  FIG. 14  shows a rear perspective view of the embodiment of the connector of  FIG. 13 . The electric drive device  100  also comprises a connector  80  which allows connecting the electronic control unit  10  with the outside by wiring. To operate, the device  100  needs on one hand power, which can be supplied by the battery of the vehicle, and on the other hand information about the mechanical torque applied to the steering column of the vehicle to thus define the torque that must be generated and delivered by the device  100 , and it also needs to be communicated with the vehicle in order to know the status of different functions thereof, such as for example the start of the vehicle, when it is moving or stopped, the speed of said vehicle, etc. To that end, said connector  80  comprises a power supply housing  81  receiving power from the outside, an electric torque signal housing  82  receiving the torque signal from the outside, and a communications housing  83  which allows receiving and sending communication signals. The connector  80  also comprises terminals  84  which allow directly connecting said connector  80  with the power board  20  through the power supply housing  81 , and therefore supplying power from the battery of the vehicle. The connector  80  also comprises terminals  85  which allow connecting directly with the control board  70  through the electric torque signal housing  82 , and therefore being able to send the torque signal to the control board  70 , and terminals  86  which allow connecting directly with the control board  70  through the communications housing  83 , thereby allowing communication from the outside to the control board  70 . 
         [0046]    The connector  80  also comprises ground connections  99 , which in the embodiment shown in  FIGS. 13 and 14 , are two in number, attached to the negative connection of the battery of the vehicle through the terminals  84  of the power supply housing  81 , and said ground connection is taken to the power board  20  and to the control board  70 . The electric drive device  100  may not comprise said ground connections  99 , as shown in a second embodiment of the connector  80  in  FIGS. 15 and 16 , but the operation of the device is more efficient with such connections because they improve radio emissions and the immunity of the device  100 . 
         [0047]    The connector  80  is attached to the device  100  laterally from the outside. The connector  80  comprises two areas, a first area  87  which is physically attached to the device  100 , said first area  87  comprising the terminals  84 ,  85 , and  86 . It also comprises a second area  88  which is attached to the first area  87  and is arranged outside the device  100  when said device  100  is completely assembled. This second area  88  comprises the power supply housing  81 , the electric torque signal housing  82 , and the communications housing  83 . In this embodiment, the first area  87  comprises two protrusions  89  projecting from the first area  87  in a plane perpendicular to the geometric axis of the motor shaft  6 . The connector  80  is thus prepared for being assembled in a portion of the device  100  which comprises housings that allow housing the protrusions  89 . Since the connector  80  comprises two areas  87  and  88 , once the connector  80  is assembled in the device  100 , it allows the first area  87  to be concealed in the device  100  and the second area  88  to be accessible from the outside to enable being connected with the housings  81 ,  82  and  83 . Therefore, and according to the connection requirements of each customer, the outer design can be modified without modifying the design of the power board  20  and control board  70 . 
         [0048]    In the embodiments shown in  FIGS. 4, 5, 7 and 8 , the heat sink  40 ;  40 ′ comprises two lobe-shaped housings  90  arranged on an edge  91  of the periphery of said heat sink  40 ;  40 ′. Once the device  100  is assembled with the motor  1 , the heat sink  40 ;  40 ′, the power board  20  and control board  70 , the housings  90  of the heat sink  40 ;  40 ′ are in view and allow housing the protrusions  89  of the first area  87 , which in this embodiment have the same identical lobe shape as the housings  90  of the heat sink  40 ;  40 ′. The protrusions  89  are assembled in the housings  90  from top to bottom, and extraction of the protrusions  89  in the radial direction, and therefore extraction of the connector  80  when the device  100  is assembled, is thereby prevented. With this design of the device  100 , the connector  80  can be inserted and fixed without requiring fixing means, such as screws. 
         [0049]    The connector  80  could be used in electric drive devices for electric power steering systems of automotive vehicles other than those disclosed herein. 
         [0050]    The outer side  47 ;  49  of the heat sink  40 ;  40 ′ comprises a vertical edge  92  running along the periphery of said outer side  47 ;  49  in a segment that is not attached to the connector  80 . The connector  80  comprises a vertical edge  93  on the upper surface of the first area  87  running along the area of intersection of said first area  87  with the second area  88 . Said edges  92  and  93  are defined such that the ends of the vertical edge  92  of the heat sink  40 ;  40 ′ and the ends of the vertical edge  93  of the connector  80  coincide when the connector  80  is assembled in the heat sink  40 ;  40 ′, thereby forming a single edge. 
         [0051]    In these embodiments, the heat sink  40 ;  40 ′ comprises three seats  94  with holes  95  substantially parallel to the geometric axis of the motor shaft  6 . Said seats  94  are arranged along the periphery of the outer side  47 ;  49  and are substantially spaced from one another. The motor case  2  at the end  101  of the side wall  102  comprises three seats  103  with holes  104  which are also substantially parallel to the geometric axis of the motor shaft  6 . These seats  103  with their holes  104  coincide with the seats  94  and the holes  95  of the outer side  47 ;  49  of the heat sink  40 ;  40 ′ when said heat sink  40 ;  40 ′ is assembled in the motor case  2 . On the other hand, the cover  50  of the device  100  comprises three seats  51  with holes  52  which are also substantially parallel to the geometric axis of the motor shaft  6 , these seats  51  projecting radially from the end  53  of the cover  50 . When the electric motor  1 , the heat sink  40 ;  40 ′, the power board  20  and the control board  70  are assembled in the device  100 , it is necessary to lastly assemble the cover  50 , and thus protect the device  100  against external conditions, such as moisture, dirt and also electromagnetic radiation. To that end, the cover  50  is arranged on the power board  20  and the control board  70 , and its end  53  is assembled against the motor case  2 , attaching the seats  51  of the cover  50  with the seats  94  of the heat sink  40 ;  40 ′ with attachment means, such as screws for example, the cover  50  overlapping in that assembly with the single edge formed by the vertical edge  92  of the heat sink  40 ;  40 ′ and the vertical edge  93  of the connector  80 . Movement of the connector  80  in the axial direction is thereby also prevented when closing the cover  50  on the motor case  2 , which prevents the entrance and exit of electromagnetic radiation as well as the entrance and exit of external elements such as dirt, and it prevents the transmission of vibrations caused by outer cables. 
         [0052]      FIG. 17  shows a block diagram showing the communications of the main parts of the power board and control board of the device of  FIG. 1 . The control board  70  and power board  20 , as well as the electric motor  1 , are depicted in this block diagram. The torque signal inputs through the torque signal housing  82  of the connector  80  and the communication inputs through the communications housing  83  of the connector  80  are arranged in the control board  20 . The torque signal housing  82  comprises three torque signal pins which allow having said torque signal in a doubly redundant manner and sending it to the microprocessor  73 . It also comprises a pin as INDEX which allows sending a signal to the microprocessor  73 , indicating the zero-crossing of the steering wheel. It also comprises four torque signal supply pins, two of which feed the torque sensor and the other two of which feed the INDEX, receiving a signal from the power source  75  of the control board  70  and from the microprocessor  73 . 
         [0053]    The communications housing  83  comprises a vehicle start signal input as IGNITION, said signal passing to the communications supervision device  74  SBC, and an input for the CAN communications bus, which is reciprocal between the communications housing  83  and the device  74 . 
         [0054]    The SBC device receives direct power from the battery BAT of the vehicle after being filtered by the choke coil  32  of the power board  20 . There is reciprocal communication from the SBC device with the microprocessor  73 , the SBC device performing monitoring functions, and it also communicates with the microprocessor  73  through a re-initializer R. The SBC device can also send secure signals to a control device  77  of the solid-state phase relays  26  and of the power supply relays  28 . 
         [0055]    In addition to the mentioned signals, the microprocessor  73  receives power from the power source  75  at 3V3 receiving a 5V analog signal as a reference, and a 5V monitoring signal for making sure that the torque sensor is correctly fed. The microprocessor  73  sends signals to the control device  77  and receives signals from the temperature sensor ST, from the shunts  29 , from the magnetic angle sensor  30  that is fed from the battery BAT through a linear voltage regulator LDO, and from a timer T. 
         [0056]    The power board  20  receives the power input from the battery of the vehicle through the external power supply housing  81  of the connector  80 . The choke coil  32  which allows eliminating noises and interferences is powered from said housing  81 , said power supply being transmitted from the choke coil  32  to the control board  70  through a connector between boards (not depicted in the drawings), and to the input of the power supply relays  28 . These relays  28  comprising the semiconductor switching elements  27  receive excitation from a drive circuit  38 , which in turn receives communication from the control device  77 , and they allow passage of the flow of direct current DC towards the power filter  33 . Said power filter  33  comprises a coil  34  and two capacitors  35  and allows filtering interferences. 
         [0057]    This power filter  33  feeds the inverter  24  in which the temperature sensor ST is arranged and mainly the inverter circuit  24 . This inverter circuit  24  comprising the semiconductor switching elements  23  allows converting direct current DC into three-phase alternating current AC powering the motor  1 . The shunts  29  which allow measuring the flow of electric current towards the motor  1  are also arranged in this inverter  24 , sending the signal indicating the level of current circulating through the shunts  20  to the microprocessor  73 , such that the microprocessor makes decisions according to said level. The inverter  24  receives excitation from the drive circuit  36  which in turn receives signals from and sends them to the microprocessor  73 . 
         [0058]    Finally, and after the electric current passes through the inverter  24  and is converted to three-phase alternating current AC, the phase relays  26  comprising the semiconductor switching elements  25  are powered, and they receive excitation from the drive circuit  37 , which in turn receives communication from the control device  77 . 
         [0059]    The three-phase alternating current AC powers the three phases  4  (U, V, W) of the electric motor  1 . The electric motor  1  comprising the shaft  6  has a magnet  9  generating a magnetic field in the position end  8 , and the power board  20  comprises the magnetic sensor  30  which senses said magnetic field and thereby determines the position of the motor shaft  6 . This intercommunication is depicted in the block diagram of  FIG. 17  by means of an arrow heading away from the motor  1  towards the angle sensor  30 .