Abstract:
A vehicle servicing method according to an exemplary aspect of the present disclosure incomes, among other things, disconnecting a high voltage battery pack of an electrified vehicle from a high voltage bus, connecting an external energy source to an inverter system controller after disconnecting the high voltage battery pack, starting an engine of the electrified vehicle using energy from an external energy source, and charging the high voltage battery pack using power from the engine.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to a vehicle servicing method for servicing an electrified vehicle. The vehicle servicing method is utilized to recharge a deeply depleted high voltage battery pack during engine fault conditions if the high voltage battery pack has an insufficient amount of charge for starting the engine. 
       BACKGROUND 
       [0002]    The need to reduce automotive fuel consumption and emissions is well known. Therefore, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle currently being developed for this purpose. In general, electrified vehicles differ from conventional motor vehicles because they are selectively driven by one or more battery powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to drive the vehicle. 
         [0003]    A full hybrid electric vehicle has two energy sources—fuel and a high voltage battery pack. The high voltage battery pack is used to start the engine, and the engine is employable to regeneratively recharge the battery pack when the state of charge (SOC) of the battery pack drops below a certain threshold value. The SOC of the battery pack can become depleted to the point that an insufficient amount of power is available to start the engine. 
       SUMMARY 
       [0004]    A vehicle servicing method according to an exemplary aspect of the present disclosure incomes, among other things, connecting an external energy source to an inverter system controller after disconnecting a high voltage battery pack from an external energy source, starting an engine of the electrified vehicle using energy from the external energy source, and charging the high voltage battery pack using power from the engine. 
         [0005]    In a further non-limiting embodiment of the foregoing method, the method includes, after starting the engine, commanding a motor to output zero torque such that it is neither generating nor accepting any energy. 
         [0006]    In a further non-limiting embodiment of either of the foregoing methods, disconnecting the high voltage battery pack includes unplugging a high voltage cable connected to the high voltage battery pack from the inverter system controller. 
         [0007]    In a further non-limiting embodiment of any of the foregoing methods, the method includes, prior to charging the battery pack, commanding the inverter system controller to discharge a high voltage bus, disconnecting the external energy source after discharging the high voltage bus, reconnecting the high voltage battery pack to the high voltage bus prior to charging the high voltage battery pack, commanding the engine to produce torque, and commanding the inverter system controller to deliver power to charge the battery pack. 
         [0008]    In a further non-limiting embodiment of any of the foregoing methods, the method includes, after connecting the external energy source, boosting incoming voltage from the external energy source. 
         [0009]    In a further non-limiting embodiment of any of the foregoing methods, starting the engine includes invoking a low power cranking mode to start the engine and declaring the engine started if a speed of the engine exceeds a predefined value. 
         [0010]    In a further non-limiting embodiment of any of the foregoing methods, the method includes setting engine to engine speed control and setting a motor to torque control mode. 
         [0011]    In a further non-limiting embodiment of any of the foregoing methods, the method includes connecting a service tool to the electrified vehicle prior to performing the vehicle servicing method. 
         [0012]    In a further non-limiting embodiment of any of the foregoing methods, the method includes communicating messages to a service technician on the service tool. 
         [0013]    In a further non-limiting embodiment of any of the foregoing methods, charging the high voltage battery pack includes commanding the engine to produce torque and generate power to charge the high voltage battery pack. 
         [0014]    In a further non-limiting embodiment of any of the foregoing methods, the method includes discharging the high voltage bus after starting the engine. 
         [0015]    In a further non-limiting embodiment of any of the foregoing methods, charging the high voltage battery includes closing at least one contactor of the high voltage battery to reconnect the high voltage battery to the high voltage bus. 
         [0016]    In a further non-limiting embodiment of any of the foregoing methods, the vehicle servicing method is performed in response to an engine fault condition if the high voltage battery pack has an insufficient amount of power necessary to start the engine. 
         [0017]    A battery charging system according to another exemplary aspect of the present disclosure includes, among other things, a high voltage battery pack, an engine, an external energy source and an inverter system controller configured to start the engine using power from the external energy source during a first step of a vehicle servicing method and supply power from the engine to recharge the high voltage battery pack during a second step of the vehicle servicing method. 
         [0018]    In a further non-limiting embodiment of the foregoing system, the system includes a service tool configured to communicate with the inverter system controller. 
         [0019]    In a further non-limiting embodiment of either of the foregoing systems, the system includes an electric motor configured to start the engine in response to a command from the inverter system controller. 
         [0020]    In a further non-limiting embodiment of any of the foregoing systems, the external energy source is a separate component from an electrified vehicle but the high voltage battery pack, the engine and the inverter system controller are each components of the electrified vehicle. 
         [0021]    In a further non-limiting embodiment of any of the foregoing systems, the high voltage battery pack includes at least one battery cell and at least one contactor. 
         [0022]    In a further non-limiting embodiment of any of the foregoing systems, the inverter system controller includes a plurality of switching devices configured to control bidirectional flow of power between the high voltage battery pack and the engine. 
         [0023]    In a further non-limiting embodiment of any of the foregoing systems, the external energy source is a lead acid battery charger. 
         [0024]    The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
         [0025]    The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  schematically illustrates a powertrain of an electrified vehicle. 
           [0027]      FIG. 2  illustrates a battery charging system of an electrified vehicle. 
           [0028]      FIG. 3  schematically illustrates a vehicle servicing method for charging a deeply depleted high voltage battery pack of an electrified vehicle during engine fault conditions. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    This disclosure details an exemplary vehicle servicing method for charging a deeply depleted high voltage battery pack of an electrified vehicle. In some embodiments, the vehicle servicing method is employed during engine fault conditions to first start the engine and then regen charge the battery pack. The high voltage battery pack is first disconnected from a high voltage bus. An external energy source is then connected to the high voltage bus. The engine of the electrified vehicle is started using energy from the electrical energy source, and the high voltage battery pack is subsequently reconnected to the high voltage bus. The high voltage battery pack is regeneratively charged using power from the engine. A battery charging system is also proposed for executing the vehicle servicing method. These and other features are discussed in greater detail in the following paragraphs of this detailed description. 
         [0030]      FIG. 1  schematically illustrates a powertrain  10  for an electrified vehicle  12 . Although depicted as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEV&#39;s and could extend to other electrified vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEV&#39;s), battery electric vehicles (BEV&#39;s) and fuel cell vehicles. 
         [0031]    In one non-limiting embodiment, the powertrain  10  is a power-split powertrain system that employs a first drive system and a second drive system. The first drive system includes a combination of an engine  14  and a generator  18  (i.e., a first electric machine). The second drive system includes at least a motor  22  (i.e., a second electric machine) and a battery pack  24 . In this example, the second drive system is considered an electric drive system of the powertrain  10 . The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels  28  of the electrified vehicle  12 . Although a power-split configuration is shown, this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids or micro hybrids. 
         [0032]    The engine  14 , which in one embodiment is an internal combustion engine, and the generator  18  may be connected through a power transfer unit  30 , such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine  14  to the generator  18 . In one non-limiting embodiment, the power transfer unit  30  is a planetary gear set that includes a ring gear  32 , a sun gear  34 , and a carrier assembly  36 . 
         [0033]    The generator  18  can be driven by the engine  14  through the power transfer unit  30  to convert kinetic energy to electrical energy. The generator  18  can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft  38  connected to the power transfer unit  30 . Because the generator  18  is operatively connected to the engine  14 , the speed of the engine  14  can be controlled by the generator  18 . 
         [0034]    The ring gear  32  of the power transfer unit  30  may be connected to a shaft  40 , which is connected to vehicle drive wheels  28  through a second power transfer unit  44 . The second power transfer unit  44  may include a gear set having a plurality of gears  46 . Other power transfer units may also be suitable. The gears  46  transfer torque from the engine  14  to a differential  48  to ultimately provide traction to the vehicle drive wheels  28 . The differential  48  may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels  28 . In one embodiment, the second power transfer unit  44  is mechanically coupled to an axle  50  through the differential  48  to distribute torque to the vehicle drive wheels  28 . In one embodiment, the power transfer units  30 ,  44  are part of a transmission  58  of the electrified vehicle  12 . 
         [0035]    The motor  22  can also be employed to drive the vehicle drive wheels  28  by outputting torque to a shaft  52  that is also connected to the second power transfer unit  44 . In one embodiment, the motor  22  is part of a regenerative braking system. For example, the motor  22  can each output electrical power to the battery pack  24 . 
         [0036]    The battery pack  24  is an exemplary electrified vehicle battery. The battery pack  24  may be a high voltage traction battery pack that includes a plurality of battery assemblies  25  (i.e., battery arrays or groupings of battery cells) capable of outputting electrical power to operate the motor  22 , the generator  18  and/or other electrical loads of the electrified vehicle  12 . Other types of energy storage devices and/or output devices can also be used to electrically power the electrified vehicle  12 . 
         [0037]    In one non-limiting embodiment, the electrified vehicle  12  has two basic operating modes. The electrified vehicle  12  may operate in an Electric Vehicle (EV) mode where the motor  22  is used (generally without assistance from the engine  14 ) for vehicle propulsion, thereby depleting the battery pack  24  state of charge up to its maximum allowable discharging rate under certain driving patterns/cycles. The EV mode is an example of a charge depleting mode of operation for the electrified vehicle  12 . During EV mode, the state of charge of the battery pack  24  may increase in some circumstances, for example due to a period of regenerative braking. The engine  14  is generally OFF under a default EV mode but could be operated as necessary based on a vehicle system state or as permitted by the operator. 
         [0038]    The electrified vehicle  12  may additionally operate in a Hybrid (HEV) mode in which the engine  14  and the motor  22  are both used for vehicle propulsion. The HEV mode is an example of a charge sustaining mode of operation for the electrified vehicle  12 . During the HEV mode, the electrified vehicle  12  may reduce the motor  22  propulsion usage in order to maintain the state of charge of the battery pack  24  at a constant or approximately constant level by increasing the engine  14  propulsion. The electrified vehicle  12  may be operated in other operating modes in addition to the EV and HEV modes within the scope of this disclosure. 
         [0039]      FIG. 2  illustrates a battery charging system  54  configured for recharging the energy storage devices (e.g., battery cells  65 ) of the high voltage battery pack  24 . For example, the battery charging system  54  can be used to charge the battery pack  24  if an engine fault condition has occurred and the battery pack  24  has an insufficient SOC available for starting the engine  14 . Exemplary engine fault conditions include low fuel pump pressure, faulty spark plug(s), blown fuse, or incorrect fuel source. Of course, these are non-limiting examples and are not intended to limit this disclosure. 
         [0040]    The exemplary battery charging system  54  includes the battery pack  24 , an inverter system controller (ISC)  56 , the motor  22 , the transmission  58  and the engine  14 . The battery charging system  54  additionally includes an external energy source  60  and a service tool  62  that may be utilized by a service technician to execute an exemplary vehicle servicing method, as is further discussed below. 
         [0041]    The battery pack  24  includes one or more battery cells  65  and contactors  64 . The contractors  64  are selectively opened/closed to disconnect/connect the battery cells  65  of the battery pack  24  to a high voltage bus  66 . For example, the contactors  64  are selectively closed to apply the DC voltage from the battery pack  24  to the high voltage bus  66 , and are selectively opened to disconnect the battery pack  24  from the high voltage bus  66 . In one non-limiting embodiment, the contactors  64  are controlled by a control module (not shown), such as a battery energy control module (BECM). In another non-limiting embodiment, a high voltage cable  72  connects the battery pack  24  to the ISC  56 . 
         [0042]    In one non-limiting embodiment, the ISC  56  is an inverter system controller combined with a variable voltage converter. The ISC  56  includes a plurality of switching devices  68  for controlling bi-directional power flow within the battery charging system  54 . In one non-limiting embodiment, the switching devices  68  are insulated-gate bipolar transistors (IGBT&#39;s). The switching devices  68  are selectively commanded to undergo switching operations for converting DC voltage from the battery pack  24  to three phase AC voltage for supplying power to the motor  22  (i.e., to propel the vehicle), or alternatively, to covert AC three phase voltage to DC voltage for electric regenerative charging the battery cells  65  of the battery pack  24 . 
         [0043]    The transmission  58  includes the gear systems necessary for utilizing the power from the motor  22  to start the engine  14  during vehicle starting conditions. The transmission  58  also transfers the power from the engine  14  to the motor  22  for regeneratively charging the battery pack  24 . 
         [0044]    Unlike the battery pack  24 , the ISC  56 , the motor  22 , the transmission  58  and the engine  14 , the external energy source  60  is a separate component from the electrified vehicle. The external energy source  60  is connectable to the ISC  56  during certain conditions, such as engine fault conditions, and can be used to start the engine  14  if the battery pack  24  is deeply depleted. In one non-limiting embodiment, the external energy source  60  is a lead acid battery charger. In another non-limiting embodiment, the external energy source  60  is a low voltage battery. Other external energy sources are also contemplated within the scope of this disclosure. 
         [0045]    The service tool  62  is connectable for communicating with the electrified vehicle. In one non-limiting embodiment, the service tool  62  is a computer that can be plugged into a data port  70  located onboard the electrified vehicle to access the vehicle&#39;s computer network. The service tool  62  enables a service technician to initiate vehicle servicing methods for servicing the electrified vehicle. 
         [0046]      FIG. 3 , with continued reference to  FIGS. 1 and 2 , schematically illustrates an exemplary vehicle servicing method  100 . In one non-limiting embodiment, the vehicle servicing method  100  is executed by a service technician to recharge the battery pack  24  during engine fault conditions if the battery cells  65  of the battery pack  24  are depleted to such a low level that an insufficient amount of power is available for starting the engine  14 . 
         [0047]    The vehicle serving method  100  begins at block  102 . By this time, the service technician has already connected the service tool  62  to the data port  70  of the electrified vehicle  12  and has confirmed that an engine fault condition has occurred and that the battery pack  24  includes an insufficient SOC for starting the engine  14 . In one non-limiting embodiment, the ISC  56  checks the operating conditions of the electrified vehicle (e.g., vehicle is parked, speed is zero, etc.) and verifies the engine fault condition once the service technician has requested the vehicle servicing method  100 . 
         [0048]    At block  104 , the high voltage cable  72  that extends between the battery pack  24  and the ISC  56  is disconnected from the ISC  56 . Next, at block  106 , the external energy source  60  is connected to the ISC  56  and is enabled for use (e.g., turned ON). In one non-limiting embodiment, the service technician can be informed to connect the external energy source  60  to the ISC  56 , such as by communicating a message that is displayed by the service tool  62 . The ISC  56  next verifies if the external energy source  60  is connected to the ISC  56  and that the DC voltage V bus  received from the external energy source  60  is within an expected range at block  108 . This may be done using a high voltage interlock (HVIL), in one non-limiting embodiment. The HVIL may be performed by either the ISC  56  or a control module, such as the BECM. 
         [0049]    The ISC  56  boosts the input voltage received from the external energy source  60 , such as to a value above 250 volts, at block  110  if the external energy source  60  is connected and the V bus  is within the expected range. Next, at block  112 , the ISC  56  commands the motor  22  to generate enough power to start the engine  14 . In one non-limiting embodiment, the ISC  56  commands the motor  22  to generate around 500 W of power to start the engine  14 . A low power cranking mode is invoked at block  114  (e.g., at least 250 RPMs), and when the engine  14  is operating at greater than 500 RPMs, the engine  14  is declared started at block  116 . 
         [0050]    At block  118 , the engine  14  is set to engine speed control and the motor  22  is commanded to output zero torque such that it is neither generating nor accepting any energy. The service technician is then informed to turn the external energy source  60  OFF at block  120 . 
         [0051]    The ISC  56  is subsequently commanded to discharge the high voltage bus  66  at block  122 . Discharging the high voltage bus  66  includes discharging the energy stored in capacitors Cy and Ci. When the external energy source  60  is used to start the engine  14 , the energy is stored in capacitors Cy, Ci and Cm. The energy is removed as a safety precaution before disconnecting the high voltage cable  72  from the ISC  56 . When a lower leg  67  of the switching devices is closed and an upper leg  69  is open, the energy stored in the capacitors Cy, Ci may be discharged along a path  71 . Alternatively, if the upper leg  69  is closed and the lower leg  67  is open, the energy may be discharged along a path  73 . 
         [0052]    The DC voltage Vbus is monitored at block  124 . In one non-limiting embodiment, the DC voltage Vbus is monitored by comparing it to the discharged voltage. If the DC voltage Vbus is zero, the service technician is informed to remove the external energy source  60  and reconnect the high voltage cable  72  to the battery pack  24  at block  126 . Alternatively, if the DC voltage Vbus is greater than zero at block  124 , the discharge time is compared with a maximum discharge time at block  128 . If the discharge time is greater than the maximum discharge time, the vehicle serving method  100  returns to block  122 . Alternatively, if the discharge time is not greater than the maximum discharge time, the vehicle servicing method  100  returns to block  120  by rechecking whether the external energy source is turned OFF. The ISC  56  next verifies if the battery pack  24  is connected to the ISC  56  and that the DC voltage V bus  is within an expected range at block  130 . 
         [0053]    If the voltage level is within a predefined range, the ISC  56  commands the contactors  64  to close to connect the battery pack  24  to the high voltage bus  66  at block  132 . In one non-limiting embodiment, the closing sequence of the contactors  64  includes closing a main negative contactor  64 - 1 , then closing a precharge contactor  64 - 2 , and then closing a main positive contactor  64 - 3  and reopening the precharge contactor  64 - 2  once the DC voltage V bus  is close the battery voltage V batt  (see  FIG. 2 ). 
         [0054]    Finally, at block  134 , the engine  14  is commanded to produce torque and generate positive power to charge the battery pack  24  and run any electrical accessories. The ISC  56  may command the motor  22  to operate in a regenerative mode to ramp up the DC voltage V bus . During the battery regenerative charging, the DC current received by the battery pack  24  is monitored to determine whether it is within a defined range. After the battery pack  24  SOC reaches a predefined value, the regen charging is complete and the vehicle servicing method  100  is exited at block  136 . 
         [0055]    Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0056]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
         [0057]    The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.