Abstract:
A vehicle power stage assembly is disclosed which may include a power stage housing, a power stage supported by the housing, and a pair of stacked DC leadframes. The pair of stacked DC leadframes are of opposite polarity and spaced apart from one another. Each of the DC leadframes may extend from the power stage and each has distal and proximal ends. The spacing between the leadframes may be such that parasitic inductances associated with current flowing through each of the leadframes at least partially cancel one another. Each of the leadframes may define a first and second side surface opposite one another. The first side surfaces may be coplanar and the second side surfaces may be coplanar. A distance between the spaced apart pair of DC leadframes may be based on a preselected amount of current and a material of the DC leadframes.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to power module assemblies for automotive vehicles. 
       BACKGROUND 
       [0002]    Electrified vehicles such as battery-electric vehicles (BEVs), plug-in hybrid-electric vehicles (PHEVs), mild hybrid-electric vehicles (MHEVs), or full hybrid-electric vehicles (FHEVs) contain an energy storage device, such as a high voltage (HV) battery. A power inverter can be electrically connected between the battery and any electric machines to convert direct current from the battery to alternating current for the electric machines. The power inverter may also convert alternating current from the electric machines to direct current for the battery. 
       SUMMARY 
       [0003]    A vehicle power stage assembly includes a power stage housing, a power stage supported by the housing, and a pair of stacked DC leadframes. The pair of stacked DC leadframes are of opposite polarity and spaced apart from one another. Each of the DC leadframes extends from the power stage and each has distal and proximal ends. The spacing between the leadframes is such that parasitic inductances associated with current flowing through each of the leadframes at least partially cancel one another. Each of the leadframes may further define a connector tab configured to electrically connect to a capacitor module. The leadframes may be arranged such that the connector tabs extend in opposite directions from one another and outer surfaces of the tabs are substantially coplanar. The leadframes may be spaced apart a distance falling within a range of 0.25 millimeters to 1.0 millimeters. Each of the leadframes may define a first and second side surface opposite one another. The first side surfaces may be coplanar and the second side surfaces may be coplanar. The leadframes may be oriented parallel to one another. A distance between the spaced apart pair of DC leadframes may be based on a preselected amount of current and a material of the DC leadframes. 
         [0004]    A vehicle power module assembly includes a frame and a power stage. The frame defines a stage cavity and a first slot open to the cavity. The power stage is disposed within the cavity and has a pair of DC leadframes extending through the first slot. The first slot is defined such that distal and proximal ends of one of the leadframes are equally spaced apart relative to corresponding distal and proximal ends of the other of the leadframes. The frame may further define a second slot open to the cavity and the power stage may further have an AC leadframe extending through the second slot. The frame may further define a signal pin slot open to the cavity. The power stage may further have at least one set of signal pins extending through the signal pin slot. The slots may be arranged relative to one another such that the DC leadframes and pins each extend from a different side of the power stage. The DC leadframes may be spaced apart a distance such that parasitic inductances associated with current flowing through each of the leadframes at least partially cancel one another. The DC leadframes may be spaced apart a distance falling within a range of 0.1 millimeters to 20.0 millimeters. The assembly may also include a capacitor module having a pair of DC leadframe receiving connectors arranged with the frame such that the connectors are spaced apart from one another at a distance equal to the spacing between the DC leadframes. 
         [0005]    A vehicle power module assembly includes a frame and a power stage. The frame defines a cavity and first and second DC slots spaced apart from one another. The power stage is disposed within the cavity and has a pair of DC leadframes of opposite polarity. One of the DC leadframes extends through one of the slots and the other of the DC leadframes extends through the other of the slots. The stage and slots are arranged with one another to position proximal and distal ends of one of the DC leadframes at equal spacings from proximal and distal ends of the other of the DC leadframes. Each of the DC leadframes may further have a tab extending from the distal end and away from other of the tabs and outer surfaces defined by each of the tabs may be coplanar. The DC leadframes may be spaced to reduce stray inductances associated with the DC leadframes. The frame may further define an AC slot arranged with the power stage such that the AC slot is on a side of the frame which does not include the DC slots. The frame may further define a pair of signal pin slots arranged with the power stage such that the signal pin slots are on a side of the frame which does not include the DC slots or the AC slot. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a schematic diagram of an example hybrid vehicle. 
           [0007]      FIG. 2  is a schematic diagram of a variable voltage converter and power inverter. 
           [0008]      FIG. 3  is a perspective view of an example of a portion of a power module assembly showing a capacitor module in phantom. 
           [0009]      FIG. 4  is a perspective view of the portion of the power module assembly of  FIG. 3 . 
           [0010]      FIG. 5A  is a perspective view of a frame of the power module of  FIG. 4 . 
           [0011]      FIG. 5B  is a side view of the frame of  FIG. 5A . 
           [0012]      FIG. 5C  is a bottom view of the frame of the power module of  FIG. 4 . 
           [0013]      FIG. 5D  is another side view of the frame of  FIG. 5A . 
           [0014]      FIG. 6  is a perspective view of a power stage of the power module of  FIG. 4 . 
           [0015]      FIG. 7  is a bottom view of the power stage of  FIG. 6 . 
           [0016]      FIG. 8  is a side view of the power stage of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
         [0018]    An example of a PHEV is depicted in  FIG. 1 , referred to generally as a vehicle  16  herein. The vehicle  16  may include a transmission  12  and is an example of an electric vehicle propelled by an electric machine  18  with assistance from an internal combustion engine  20 . The vehicle  16  may be connectable to an external power grid. The electric machine  18  may be an AC electric motor depicted as a motor  18  in  FIG. 1 . The electric machine  18  receives electrical power and provides torque for vehicle propulsion. The electric machine  18  may also function as a generator for converting mechanical power into electrical power through regenerative braking 
         [0019]    The transmission  12  may be a power-split configuration. The transmission  12  may include the first electric machine  18  and a second electric machine  24 . The second electric machine  24  may be an AC electric motor depicted as a generator  24  in  FIG. 1 . Similar to the first electric machine  18 , the second electric machine  24  may receive electrical power and provide output torque. The second electric machine  24  may also operate as a generator for converting mechanical power into electrical power and optimizing power flow through the transmission  12 . In other embodiments, the transmission may not have a power-split configuration. 
         [0020]    The transmission  12  may include a planetary gear unit (not shown) and may operate as a continuously variable transmission and without any fixed or step ratios. The transmission  12  may also include a one-way clutch (O.W.C.) and a generator brake  33 . The O.W.C. may be coupled to an output shaft of the engine  20  to control a direction of rotation of the output shaft. The O.W.C. may prevent the transmission  12  from back-driving the engine  20 . The generator brake  33  may be coupled to an output shaft of the second electric machine  24 . The generator brake  33  may be activated to “brake” or prevent rotation of the output shaft of the second electric machine  24  and of the sun gear  28 . Alternatively, the O.W.C. and the generator brake  33  may be replaced by implementing control strategies for the engine  20  and the second electric machine  24 . The transmission  12  may be connected to a driveshaft  46 . The driveshaft  46  may be coupled to a pair of drive wheels  48  through a differential  50 . An output gear (not shown) of the transmission may assist in transferring torque between the transmission  12  and the drive wheels  48 . The transmission  12  may also be in communication with a heat exchanger  49  or an automatic transmission fluid cooler (not shown) for cooling the transmission fluid. 
         [0021]    The vehicle  16  includes an energy storage device, such as a traction battery  52  for storing electrical energy. The battery  52  may be a HV battery capable of outputting electrical power to operate the first electric machine  18  and the second electric machine  24  as further described below. The battery  52  may also receive electrical power from the first electric machine  18  and the second electric machine  24  when they are operating as generators. The battery  52  may be a battery pack made up of several battery modules (not shown), where each battery module contains a plurality of battery cells (not shown). Other embodiments of the vehicle  16  contemplate alternative types of energy storage devices, such as capacitors and fuel cells (not shown) that may supplement or replace the battery  52 . 
         [0022]    A high voltage bus may electrically connect the battery  52  to the first electric machine  18  and to the second electric machine  24 . For example, the vehicle  16  may include a battery energy control module (BECM)  54  for controlling the battery  52 . The BECM  54  may receive input indicative of certain vehicle conditions and battery conditions, such as battery temperature, voltage, and current. The BECM  54  may calculate and estimate parameters of the battery  52 , such as a battery state of charge (BSOC) and a battery power capability (Pcap). The BECM  54  may provide output that is indicative of the BSOC and Pcap to other vehicle systems and controllers. 
         [0023]    The vehicle  16  may include a DC-DC converter or variable voltage converter (VVC)  10  and an inverter  56 . The VVC  10  and the inverter  56  may be electrically connected between the battery  52  and the first electric machine  18  and the second electric machine  24 . The VVC  10  may “boost” or increase a voltage potential of electrical power provided by the battery  52 . The VVC  10  may also “buck” or decrease voltage potential of the electrical power provided to the battery  52 . The inverter  56  may invert DC power supplied by the battery  52  via the VVC  10  to AC power for operating each of the electric machines  18  and  24 . The inverter  56  may also rectify AC power provided by each of the electric machines  18  and  24  to DC for charging the battery  52 . In other examples, the transmission  12  may operate with multiple inverters, such as one inverter associated with each of the electric machine  18  and  24 . The VVC  10  includes an inductor assembly  14  (further described in relation to  FIG. 2 ). 
         [0024]    The transmission  12  is shown in communication with a transmission control module (TCM)  58  for controlling the electric machines  18  and  24 , the VVC  10 , and the inverter  56 . The TCM  58  may be configured to monitor conditions of each of the electric machines  18  and  24  such as position, speed, and power consumption. The TCM  58  may also monitor electrical parameters (e.g., voltage and current) at various locations within the VVC  10  and the inverter  56 . The TCM  58  provides output signals corresponding to this information for other vehicle systems to utilize. 
         [0025]    The vehicle  16  may include a vehicle system controller (VSC)  60  that communicates with other vehicle systems and controllers for coordinating operations thereof. Although shown as a single controller, it is contemplated that the VSC  60  may include multiple controllers to control multiple vehicle systems and components according to an overall vehicle control logic or software. 
         [0026]    The vehicle controllers, such as the VSC  60  and the TCM  58 , may include various configurations of microprocessors, ASICs, ICs, memory (e.g., FLASH, ROM, RAM, EPROM and/or EEPROM), and software code to cooperate with one another to perform vehicle operations. The controllers may also include predetermined data, or “look up tables,” which are accessible from the memory and may be based on calculations and test data. This predetermined data may be utilized by the controllers to facilitate control of the vehicle operations. The VSC  60  may communicate with other vehicle systems and controllers (e.g., the BECM  54  and the TCM  58 ) over one or more wired or wireless connections using bus protocols such as CAN and LIN. The VSC  60  may receive input (PRND) that represents a current position of the transmission  12  (e.g., park, reverse, neutral or drive). The VSC  60  may also receive input (APP) that represents an accelerator pedal position. The VSC  60  may provide outputs representative of a desired wheel torque, desired engine speed, and a generator brake command to the TCM  58 ; and contactor control to the BECM  54 . 
         [0027]    The vehicle  16  may include an engine control module (ECM)  64  for controlling the engine  20 . The VSC  60  provides output, such as desired engine torque, to the ECM  64  that may be based on a number of input signals including APP and may correspond to a driver&#39;s request for vehicle propulsion. 
         [0028]    The battery  52  may periodically receive AC energy from an external power supply or grid via a charge port  66 . The vehicle  16  may also include an on-board charger  68  which receives the AC energy from the charge port  66 . The charger  68  may include AC/DC conversion capability to convert the received AC energy into DC energy suitable for charging the battery  52  during a recharge operation. Although illustrated and described in the context of a PHEV, it is contemplated that the inverter  56  may be implemented with other types of electrified vehicles, such as a FHEV or a BEV. 
         [0029]    Referring to  FIG. 2 , an example of an electrical schematic of the VVC  10  and the inverter  56  is shown. The VVC  10  may include a first switching unit  70  and a second switching unit  72  for boosting the input voltage (V_bat) to provide output voltage (V_dc). The first switching unit  70  is shown with a first transistor  74  connected in parallel to a first diode  76  and with their polarities switched (referred to as anti-parallel herein). The second switching unit  72  is shown with a second transistor  78  connected anti-parallel to a second diode  80 . Each of the transistors  74  and  78  may be a type of controllable switch (e.g., an insulated gate bipolar transistor (IGBT) or field-effect transistor (FET)). Additionally, each of the transistors  74  and  78  may be individually controlled by the TCM  58 . The inductor assembly  14  is depicted as an input inductor that is connected in series between the battery  52  and the switching units  70  and  72 . The inductor assembly  14  may generate magnetic flux when a current is supplied. When the current flowing through the inductor assembly  14  changes, a time-varying magnetic field is created and a voltage is induced. Other embodiments of the VVC  10  may include alternative circuit configurations (e.g., more than two switches). 
         [0030]    The inverter  56  may include a plurality of half-bridges  82  stacked in an assembly. Each of the half-bridges  82  may be packaged as a power stage. In the illustrated example, the inverter  56  includes six half-bridges (though  FIG. 2  labels only one complete half-bridge  82 ), three for the motor  18  and three for the generator  24 . Each of the half-bridges  82  may include a positive DC lead  84  that is coupled to a positive DC node from the battery  52  and a negative DC lead  86  that is coupled to a negative DC node from the battery  52 . Each of the half-bridges  82  may also include a first switching unit  88  and a second switching unit  90 . The first switching unit  88  includes a first transistor  92  connected in parallel to a first diode  94 . The second switching unit  90  includes a second transistor  96  connected in parallel to a second diode  98 . The first transistor  92  and the second transistors  96  may be IGBTs or FETs. The first switching unit  88  and the second switching unit  90  of each of the half-bridges  82  converts the DC power of the battery  52  into a single phase AC output at the AC lead  100 . Each of the AC leads  100  is electrically connected to the motor  18  or generator  24 . In this example, three of the AC leads  100  are electrically connected to the motor  18  and the other three AC leads  100  are electrically connected to the generator  24 . 
         [0031]    During operation of power modules, stray inductance may play a role in determining a voltage spike of a semiconductor device during a switching event. A low stray inductance power module design may be desired to promote low voltage spikes and low switching losses. 
         [0032]      FIG. 3  shows an example of a portion of a power module assembly for use with an electrified vehicle, referred to generally as a power module assembly  200  herein. The power module assembly  200  may include a plurality of power modules stacked in an array.  FIG. 4  shows an example of a power module of the plurality of power modules, referred to generally as a power module  202  herein. Each power module  202  of the power modules assembly  200  may include a power stage  204  retained by a frame  206 . The power stage  204  may be adjacent to one or more thermal plates, such as thermal plates  208 , and may include a DC terminal  205 . A pair of endplates  207  may retain the power modules  202  therebetween. The thermal plates  208  may be in thermal communication with adjacent power stages  204  of the plurality of power modules. The frame  206  may orient the thermal plates  208  in a location proximate to the power stages  204  to provide a flow path for coolant to assist in managing thermal conditions of the power stages  204 . One of the endplates  207  may include an inlet  210  and an outlet  212  to assist in delivering and removing coolant from the thermal plates  208 . It is contemplated that other configurations are available for the locations of the inlet  210  and the outlet  212 . 
         [0033]    Each frame  206  may define a power stage cavity  214  to receive one of the power stages  204 . Each frame  206  may define a plurality of apertures or slots sized to receive components of the power stage  204 .  FIGS. 5A through 5D  show examples of locations for the apertures or slots. For example, each frame  206  may define a pair of DC slots  220 , an AC slot  222 , a first signal pin slot  224 , and a second signal pin slot  226 . The slots may be located on different sides of the frame  206 . The AC slot  222  may be sized to receive an AC leadframe. The first signal pin slot  224  and the second signal pin slot  226  may each be sized to receive one or more signal pins. The DC slots  220  may be spaced apart from one another and sized to receive DC leadframes of the DC terminal  205 . 
         [0034]    For example and now additionally referring to  FIGS. 6 through 8 , each DC terminal  205  may include a pair of DC leadframes, referred to as a first DC leadframe  230  and a second DC leadframe  232 . The first DC leadframe  230  and the second DC leadframe  232  may be of opposite polarities and may be electrically connected to receiving connectors (not shown) of a capacitor module  234  (the capacitor module  234  is shown partially transparent in  FIG. 1  to provide a view to components of the power module assembly  200 ). Each power stage  204  may include an AC leadframe  240 , a first set of signal pins  242 , and a second set of signal pins  244 . The AC leadframe  240  may be electrically connected to an electric machine, such as the electric machines described above. The first set of signal pins  242  and the second set of signal pins  244  may be electrically connected to a gate drive board  245  (shown in  FIG. 1 ). 
         [0035]    The first DC leadframe  230  and the second DC leadframe  232  may extend from the power stage  204  and be spaced apart in a stacked configuration. For example, the first DC leadframe  230  may extend through one of the DC slots  220  of the frame  206  and the second DC leadframe  232  may extend through the other of the DC slots  220 . It is also contemplated that the frame  206  may define a single slot or opening to receive both the first DC leadframe  230  and the second DC leadframe  232  instead of two separate slots. The first DC leadframe  230  and the second DC leadframe  232  may extend in parallel to one another from the power stage  204  and such that a proximal end  246  of the first DC leadframe  230  is spaced apart from a proximal end  248  of the second DC leadframe  232  at a distance equal to a spacing between a distal end  250  of the first DC leadframe  230  and a distal end  252  of the second DC leadframe  232 . 
         [0036]    For example, the first DC leadframe  230  and the second DC leadframe  232  may be spaced apart at a distance  260 . The distance  260  may be based on characteristics/materials of the components of the power stage  204  and also on a preselected amount of current which will flow therethrough in order to minimize stray inductance. For example, the first DC leadframe  230  and the second DC leadframe  232  may be spaced apart from one another within a range of 0.1 millimeters to 20.0 millimeters. 
         [0037]    The spacing between the first DC leadframe  230  and the second DC leadframe  232  may assist in reducing stray inductance which may result when current is flowing through the leadframes. For example, a change in current or a current spike in a circuit may induce a voltage or electrical field which may negatively affect the leadframes or conductors nearby. Spacing the first DC leadframe  230  and the second DC leadframe  232  apart from one another at the distance  260  may reduce stray inductance in comparison to other DC leadframe configurations such as a side-by-side configuration similar to a relationship shown in  FIG. 6  between the first set of signal pins  242  and the second set of signal pins  244 . The DC slots  220  may also be spaced apart corresponding to the distance  260  to assist in promoting the parallel relationship between the DC leadframes which may assist in promoting a cancellation of mutual inductance from the DC leadframes to allow low voltage spikes during switching events. 
         [0038]    The first DC leadframe  230  may include a first tab  270  extending from the distal end  250 . The second DC leadframe  232  may include a second tab  272  extending from the distal end  252 . The first tab  270  and the second tab  272  may be configured to electrically connect to a capacitor module, such as the capacitor module  234 , and may extend in opposite directions from one another. The first tab  270  defines an outer surface  271 . The second tab  272  defines an outer surface  273 . The outer surface  271  and the outer surface  273  may define planes coplanar or substantially coplanar to one another. The first DC leadframe  230  may include opposing side surfaces  275  defining planes parallel to one another. The second DC leadframe  232  may include opposing side surfaces  277  defining planes parallel to the planes defined by the side surfaces  275  of the first DC leadframe  230  such that the corresponding side surfaces are coplanar. 
         [0039]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the disclosure that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.