Patent Application
20220169237
The present disclosure relates to systems and methods for optimizing the electric drive performance of a hybrid electric, battery electric, or extended-range electric vehicle, as well as other mobile platforms having an electrified powertrain. As appreciated in the art, an electrified powertrain is “electrified” in the sense of having a high-voltage bus powering operation of one or more rotary electric machines. For example, a hybrid electric motor vehicle includes multiple different prime movers, typically an internal combustion engine and one or more electric traction motors. Output torque from the engine and/or the traction motor(s) ultimately powers one or more drive axles or road wheels during different drive modes. The relative torque contribution from the various prime movers is selected in real-time based by an onboard controller based on a driver-requested torque and a myriad of other performance parameters. In contrast, a battery electric vehicle is propelled solely by motor torque from the energized traction motor(s). An extended-range electric vehicle (EREV) includes a small engine that may be decoupled from the vehicle's drive line. In the EREV configuration, therefore, the engine is used as a standby electric generator for extending the vehicle's electric operating range, as opposed to powering the vehicle as a prime mover.
When an electric traction motor is as part of an electrified powertrain, the electric traction motor is frequently configured as polyphase/alternating current (AC) machine. Therefore, a power inverter is disposed between a wound stator of the traction motor and an onboard voltage supply, with the latter typically embodied as a high-voltage rechargeable direct current (DC) propulsion battery pack. Switching state control of individual semiconductor switches arranged within the TPIM converts a DC input voltage from the battery pack into a polyphase/AC output voltage. The AC output voltage from the inverter sequentially energizes the stator's field windings and ultimately imparts rotation to a machine rotor. Loading of the traction motor and inverter is carefully controlled and limited according to a calibrated set of thermal and other performance capability limits. Accordingly, an electric traction motor may be situationally de-rated or load-reduced in real-time by an onboard controller to protect the inverter, traction motor, and other sensitive components of the electrified powertrain.
The present disclosure pertains to real-time operational control of an electrified powertrain of a motor vehicle or other mobile platform having at least one electric traction motor connected to and driven by a respective power inverter, the latter of which is referred to hereinafter as a traction power inverter module (TPIM). The method described herein situationally and temporarily enables entry into an enhanced “maximum performance” mode, abbreviated herein as “MPM” for simplicity. This occurs via selective application of an extended inverter limit (“EIL”) as described below, with EIL temporarily expanding upon more limited default/normal inverter limit (“NIL”).
As entry into MPM is restricted by the controller to certain forward-looking performance conditions in which MPM could be reliably implemented for a full duration of a boosted driving maneuver, i.e., one in which EIL is temporarily applied in lieu of the default NIL noted above, a present MPM availability status is communicated in an intuitive manner to the operator aboard the vehicle to help manage the operator's performance expectations. In other words, the operator is informed when MPM will be available for the duration of the boosted driving maneuver, e.g., a 0-60 MPH acceleration maneuver. Additionally, for multi-axle/multi-motor embodiments of the present electrified powertrain, aspects of the disclosure apply a costing function or other torque arbitration strategy to balance thermal loading and wear of the various electric machines/TPIMs over time, while still providing the expected boosted level of performance provided by operation in MPM.
As is well understood in the art, power inverter limits are informed by short-term and long-term durability effects on sensitive power electronic hardware of an electrified powertrain, principally the switching junctions of the tiny semiconductor switches used to construct each TPIM. Such limits are used to trigger automatic de-rating actions via modulation of the duty cycle used to control the ON/OFF conducting states of such switches. De-rating actions would ordinarily be performed by the controller when inverter/motor temperatures and/or other relevant control values exceed calibrated limits. EIL within the scope of the present disclosure is therefore “extended” in the sense of increasing or expanding the above-noted NIL/default inverter limits or operating ranges normally enforced outside of occasional operation in MPM.
In an exemplary embodiment, a method for controlling an electrified powertrain having an electric traction motor and a TPIM includes determining, via a controller, each of a current component capability and a current use case of the electrified powertrain. In response to the current component capability being less than a calibrated capability threshold and the current use case matching a predetermined approved use case, the method includes determining whether a predetermined margin exists in the current component capability for operating the electrified powertrain in the MPM for a full duration of a boosted driving maneuver.
The method also includes receiving input signals indicative of a requested torque, the requested torque being a desired output torque level of the electric traction motor. In response to the input signals when the predetermined margin exists, the method additionally includes temporarily applying an EIL of the TPIM, via the controller, to thereby enable the MPM. Application of the EIL allows operation of the electric traction motor to occur above default torque and speed operating limits for the full duration of the boosted driving maneuver.
The method may include communicating an availability status of the MPM to an operator of the electrified powertrain via an indicator device prior to applying the EIL, with the availability status being indicative of an availability of the MPM for the full duration of the boosted driving maneuver.
Some embodiments include disabling the EIL via the controller in response to the current component capability not exceeding the calibrated capability threshold or the current use case not matching the predetermined approved use case. The predetermined approved use case may be stored in memory of the controller, in which case determining the current use case of the electrified powertrain includes comparing a present use case of the electrified powertrain to the predetermined use case.
The electrified powertrain may include an accelerator pedal, with the input signals including an amount of pedal travel of the accelerator pedal, and with the predetermined approved use case being a wide-open throttle or wide-open pedal condition of the accelerator pedal indicative of a predetermined acceleration event. The predetermined approved use case in some embodiments of the method is an acceleration-from-a-standstill maneuver and/or a high-speed passing maneuver.
The method may include selectively disabling the EIL in response to an active traction control state.
The indicator device may be optionally configured as a digital gauge. In such a case, the controller communicates the availability status of the MPM as part of the method by illuminating one or more light-emitting diodes of the digital gauge with a color indicative of the availability status.
The electric traction motor in some configurations includes a plurality of electric traction motors, the TPIM includes a plurality of TPIMs each connected to a respective one of the electric traction motors, and the electrified powertrain includes a plurality of drive axles each coupled to a respective one of the electric traction motors. The controller in such an exemplary embodiment is configured to execute a costing function to allocate the desired torque to the drive axles during the MPM to thereby balance thermal loading and wear of the electric traction motors and the TPIMs.
In another aspect of the disclosure, an electrified powertrain includes a direct current (DC) power supply configured to provide a DC voltage, a polyphase electric traction motor having a stator and a rotor, the latter being configured to couple to a mechanical load. The electrified powertrain in this embodiment also includes a TPIM configured to convert the DC voltage from the DC power supply to an alternating current (AC) voltage, and to deliver the AC voltage to the stator. A controller is configured to execute the method described above.
A motor vehicle is also disclosed herein having road wheels, an accelerator pedal, and an electrified powertrain. The electrified powertrain includes a high-voltage battery pack providing a DC voltage, a TPIM, and a polyphase electric traction motor having a stator and a rotor, with the rotor coupled to one or more of the road wheels. A controller of the electrified powertrain is configured to execute the present method as described herein.
The above features and advantages, and other features and attendant advantages of this disclosure, will be readily apparent from the following detailed description of illustrative examples and modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes combinations and sub-combinations of the elements and features presented above and below.
The present disclosure is susceptible of embodiment in many different forms. Representative examples of the disclosure are shown in the drawings and described herein in detail as non-limiting examples of the disclosed principles. To that end, elements and limitations described in the Abstract, Introduction, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference, or otherwise.
For purposes of the present description, unless specifically disclaimed, use of the singular includes the plural and vice versa, the terms “and” and “or” shall be both conjunctive and disjunctive, “any” and “all” shall both mean “any and all”, and the words “including”, “containing”, “comprising”, “having”, and the like shall mean “including without limitation”. Moreover, words of approximation such as “about”, “almost”, “substantially”, “generally”, “approximately”, etc., may be used herein in the sense of “at, near, or nearly at”, or “within 0-5% of”, or “within acceptable manufacturing tolerances”, or logical combinations thereof.
Referring to the drawings, wherein like reference numbers refer to like features throughout the several views, an electrified powertrain 11 configured to selectively enter an enhanced maximum performance mode (“MPM”) is schematically depicted in
For illustrative simplicity, select components of the electrified powertrain 11 are shown and described in detail below while other components are omitted. The electrified powertrain 11 may be used aboard the motor vehicle 10 or another mobile platform, e.g., watercraft, aircraft, rail vehicles, etc. In the depicted representative embodiment of
The electrified powertrain 11 includes an electric traction motor (ME) 14, which in the illustrated embodiment is coupled to the rear road wheels 15R via an output member 17 and respective drive axles 19-1 and 19-2. Alternatively, the electric traction motor 14 may be embodied as individual electric traction motors 14-1 and 14-2 respectively coupled to the drive axles 19-1 and 19-2. The electric powertrain 11 may include another electric traction motor (ME) 114 coupled to the front road wheels 15F via another output member 117 and a drive axle 119. Thus, the particular number and arrangement of the electric traction motors 14, 14-1, 14-2, and/or 114 may vary with the application.
The electric traction motors 14 and 114 are coupled to and powered by a respective first and second traction power inverter module (TPIM-1) 20-1 and (TPIM-2) 20-2. For illustrative simplicity, associated TPIMs for the optional electric traction motors 14-1 and 14-2 arranged on drive axles 19-1 and 19-2 are omitted from
Described herein in relative terms as stated percentages, the default NIL 51 are enforced by the controller 50 up to 100% of a calibrated baseline thermal limit or threshold, with inverter temperature typically being a particular value encoded in control input signal (arrow CO to the controller 50 and used for this purpose. Using a nominal temperature threshold T100%, for example, de-rating via switching control of the TPIMs 20-1 and/or 20-2 would occur when the measured or estimated temperature exceeds T100%. Operation according to the EIL 53 thus temporarily increases the limits provided by the NIL 51.
For example, T100% of the NIL 51 in a non-limiting representative scenario could be increased via application of the EIL 53, e.g., to T129%. Upon application of the EIL 53, the new control threshold increases to T129%. Importantly, the controller 50 enters MPM not when present conditions such as an instantaneous temperature fall within the EIL 53, but rather when the impending EIL-boosted driving maneuver can be completed without exceeding T129% at any point of the boosted driving maneuver. MPM/EIL entry conditions and thresholds are calibratable to cover different permitted use cases across a wide range of vehicles, weather conditions, drive modes, and/or operators to minimize adverse hardware effects and optimize operator satisfaction. Within the scope of the present disclosure, therefore, entry into MPM is selectively permitted when a boosted electric propulsion capability is expected, via modeling, estimation, or other forward-looking logic of the controller 50, to remain available over the full duration of the impending boosted driving maneuver, with entry into MPM not otherwise permitted.
The present approach may be understood with reference to a representative 0-60 MPH acceleration maneuver before which an inverter/motor temperature falls well within an allowed temperature range. This alone would not be sufficient grounds for launching under EIL 53 in accordance with the present control strategy. Instead, the controller 50 would situationally and conditionally allow entry into MPM once the controller 50 ascertains whether, at completion of the MPM, thermal or other relevant conditions remain within the EIL 53. At the same time, the controller 50 communicates an availability status to the operator to help manage performance expectations. Other aspects of the disclosure may be used to balance thermal loading and component wear aboard the electrified powertrain 11. The various aspects of the strategy are described in detail below with reference to
With continued reference to
The electric traction motor 14 in the illustrated embodiment is a polyphase/AC rotary electric machine having the cylindrical rotor 14R and a cylindrical stator 14S. In a typical radial flux configuration, the rotor 14R may be coaxially arranged with respect to the stator 14S, such that the stator 14S surrounds the rotor 14R, with axial flux-type machines also being usable within the scope of the present disclosure. The rotor 14R is coupled to a mechanical load, such as one or more of the road wheels 15R, via output member 17. Output member 17, which may be embodied as a rotatable gear set, shaft, or other mechanical mechanism, may be connected to the rear road wheels 15R via drive axles 19-1 and/or 19-2 and/or an intervening gear box/transmission (not shown), with the output member 17 ultimately transmitting output torque (arrow To) from the electric traction motor 14 to the rear road wheel(s) 15R to propel the vehicle 10.
The present teachings may be applied to a single-motor configuration in which the electric traction motor 14 is the sole prime mover of the electrified powertrain 11. Alternatively, the additional traction motor 114 with a stator 1145 and rotor 114R may be used to power the front road wheels 15F, e.g., using the TPIM 20-2, or the individual electric traction motors 14-1 and 14-2 may be disposed on the partial axles 19-1 and 19-2, such that the motor vehicle 10 has two or three traction motors in total. For simplicity, although multiple electric traction motors and TPIMs may be used in the scope of the disclosure as noted above, operation of a method 100 in accordance with the present disclosure is described herein using the electric traction motor 14 and its connected TPIM 20-1 as representative hardware.
To optimize electric drive performance, the controller 50 and the TPIM 20-1 utilize intelligent system controls and hardware calibration flexibility, via execution of a method 100 as described below with reference to
Still referring to
The controller 50 of
For the purposes of executing the method 100, the controller 50 is equipped with application-specific amounts of the volatile and non-volatile memory (M) and one or more of processor(s) (P), e.g., microprocessors or central processing units, as well as other associated hardware and software, for instance a digital clock or timer, input/output circuitry, buffer circuitry, Application Specific Integrated Circuits (ASICs), systems-on-a-chip (SoCs), electronic circuits, and other requisite hardware as needed to provide the programmed functionality. The indicator device 25, such as a digital gauge, display, and/or light-emitting diodes, may be mounted within a passenger compartment of the representative vehicle 10 in easy view of the operator. Such an indicator device 25 is in communication with the controller 50, e.g., over low-voltage differential lines and/or wirelessly, and is responsive to availability status signal (arrow CCG) to enable the controller 50 to inform an operator of the vehicle 10 as to the present availability of the MPM/EIL. The process of discerning precisely when to allow entry into such a mode will now be described with reference to
Referring to
Commencing with logic block B 101 of
In response to the input signals (arrow CI), the controller 50 accesses the NIL 51 and the EIL 53, such as by accessing a lookup table in memory (M) of the controller 50. This enables the controller 50 to determine the current use case and component compatibility (“Det UC, Comp Cap”) of the electrified powertrain 11. With respect to the latter term “use case” as employed herein, a given manufacturer of the motor vehicle 10 shown in
As understood in the art, a common performance benchmark for evaluating certain performance vehicles is its 0-60 MPH (0-96.6 KPH) acceleration performance. Acceleration during high-acceleration passing maneuvers or under other driving conditions likewise may be an enabling use condition within the scope of the disclosure. Thus, a manufacturer may limit execution of the method 100 and entry into MPM to certain makes or models of the motor vehicle 10 of
With respect to component durability/capability, thermodynamic values potentially affecting the short-term and long-term performance and durability of the electrified powertrain 11 of
Logic block B102 of
At logic block B104 of
At logic block B106, the controller 50 next compares the current component capability to a calibrated capability threshold, which may be an aggregate or blended combination of different component capabilities and thresholds as described below with reference to
As part of logic block B106, an embodiment may be contemplated in which the controller 50 looks to the present temperatures of the electric traction motor 14, TPIM 20-1, and/or other affected hardware components and determines whether such values fall within a range encoded in the EIL 53. However, this is not the end of the analysis in logic block B106. The controller 50 is also programmed to look ahead in time to an end of the impending MPM-boosted maneuver to determine whether, at the maneuver's anticipated completion, the affected components will not be outside of their respective limits as encoded in the EIL 53.
By way of example, one may assume the NIL 51 of
Instead, the controller 50 of
In this manner, the controller 50 shown in
Logic block B108 is arrived at when either the current use condition (logic block B104) or the current component capability (logic block B106) precludes entry into MPM. In this instance, the controller 50 of
Logic block B110 is arrived at when the current use condition (block B104) and the current component capabilities (block B106) both permit entry into MPM. In this instance, the controller 50 of
At logic block B112, the controller 50 of
By way of example and not limitation, a possible use scenario is one in which a driver of a high-performance version of the motor vehicle 10 is stopped at a traffic light. When the light changes, the driver may expect an immediate acceleration boost that would ordinarily accompany MPM operation. However, if the current use case is not enabled and/or a current component capability is at an unfavorable level, thus precluding entry into MPM as explained above, the driver would not experience the expected acceleration response when the light turns green and the driver fully depresses the accelerator pedal 22. In this case, the driver's expected performance will not be delivered by the electrified powertrain 11.
Absent use of the indicator device 25, the driver in this exemplary scenario might not be aware of non-availability, and may interpret the lack of boost as a fault or deficiency in the electrified powertrain 11. Likewise, MPM could be enabled but discontinued midway through a boosted driving maneuver, which could lead to driver dissatisfaction in a similar manner. Feedback enabled by logic block B112 is therefore intended to alleviate uncertainty as to the present and sustained availability of MPM, or lack thereof, while possibly conveying other information of interest to the driver. In this manner, the driver remains fully aware of when boosted performance may be expected, as enabled by imposition of the EIL 53, and when the same driver could reasonably expect normal/default acceleration performance within the scope of the NIL 51 of
While a range of embodiments for the indicator device 25 are possible within the scope of the disclosure, a few representative examples are depicted for use in the motor vehicle 10 of
Alternative or complementary indicator devices 25 may include a light bulb G2 such as one or more color-coded LEDs, e.g., in keeping with the green, amber, and red example of gauge G1, or another suitable visual indicator, or a digital bar gauge G3 presenting the information of gauge G1 in a simpler manner, and perhaps requiring less surface area to implement on an instrument panel. Visual feedback enabled by the indicator device 25 may be enhanced in some embodiments using haptic and/or audio feedback. One or more LEDs of the digital bar gauge G3 or either of gauges G1 or G2 may be illuminated with a color indicative of the availability status. In the various embodiments, the gauge G1, G2, or G3 may be responsive to the availability status signal (arrow CCG) shown in
The control logic 50L of
At logic block B203, a magnitude of the generic variable (VAR1) may be compared to predetermined limits to determine the above-noted component capability. Trace 30 corresponds to long-term component limits, with trace 130 corresponding to short-term component limits. As noted above, the controller 50 applies the EIL 53 if the long-term capability of trace 30 is at its maximum. The controller 50 would then exit EIL 53 if the short-term capability (trace 130) is no longer at maximum. Because the long-term component capability (trace 30) has a more conservative margin (30M) built in, the controller 50 would be able to complete the boosted driving maneuver in MPM before the temperature or other relevant parameter changes too much.
For example, trace 30 may be used to define discrete performance regions, with three such performance regions labeled I, II, and III in the area under the limit trace 30. By way of illustration and not limitation, the generic variable (VAR1) may be a temperature of the TPIM 20-1, with the regions I, II, and III respectively corresponding to “too cold”, “acceptable”, and “too hot”. Logic block B203 then outputs a corresponding component capability value 32 (“CompCap 1”) to logic block B206. Similar traces (not shown) may be used for a multiple (N) of other variables, including some or all of the input signals (CCI) in
Logic blocks B204T and B204F respectively entail de-rating the electric traction motor 14/TPIM 20-1 or other TPIMs and motors within the electrified powertrain 11, in response to the fault determination of logic block B202. In logic block B204T, a default setting may correspond to 0% de-rating, i.e., the TPIM 20-1 and/or the electric traction motor 14 may be initially set to operate at a default torque and speed setting or operating point. In contrast, logic block B204F is executed in response to detection of an electrical fault at logic block B202. Depending on the nature of the detected electrical fault, logic block B204F may include de-rating the TPIM 20-1 by 100% for serious faults, or de-rating by some lesser amount to provide limited functionality of the electric traction motor 14. The method 200 then proceeds to logic block B205.
At logic block B205, the controller 50 may arbitrate between the outputs of logic blocks B204T and B204F based on the present result of logic block B202, e.g., over a calibrated sampling interval, with the controller 50 outputting a de-rating percentage (“% DRT”) based on the results. Logic block B205 may include averaging the outputs of logic blocks B204T and B204F, or weighting the output of one of the logic blocks B204T or B204F more than the other in different embodiments, or calculating the derating percentage using other criteria, e.g., a formula. The de-rating percentage is then provided to logic block B208.
Logic block B206 may entail receiving the 1, . . . N different possible component capabilities from logic block(s) B203 as described above, and then finding the most-restricted or limited of the component capabilities using a comparator or other suitable minimum (Min) function. The method 200 then feeds the minimum component capability to logic block B208.
At logic block B208, the controller 50 may multiply the outputs of blocks B205 and B208 to determine the EIL limits (“EIL Cap”) for use in controlling the electrified powertrain 11 once EIL is enabled at logic block B110 of
Within the scope of the disclosure, it may be prudent for component warranty exposure purposes to curtail or prevent entry into MPM when the electrified powertrain 11 operates in a partial-pedal or single-axle use case. For instance, referring again to
However, operating in this manner may increase thermal loading and wear, and short-term or long-term warranty exposure on a corresponding electric traction motor 14 or 114, e.g., for driving the rear road wheels 15. The controller 50 may therefore preclude MPM or at least adjust torque distribution during operation in MPM in response to an active traction control state, or the controller 50. The actual torque distribution may be arbitrated in real time by the controller 50, in other words, to provide something short of a full wide-open throttle or pedal performance on a given one of the drive axles 19.
Referring now to
Outputs of the optimization block 60 include multiple different axle torques from different electric traction motors, nominally Ml, M2, and M3, and corresponding allocated portions of the total torque request (arrow TREQ), i.e., Axl1 TREQ, Axl2 TREQ, and Axl3 TREQ. In the exemplary embodiment of
The optimization block 60 of
As an illustrative example, before allocating a given percentage of the total torque request (arrow TREQ) to a given drive axle 119, 19-1, or 19-2, the controller 50 may use the illustrated costing approach to determine the effect of doing so on a given motor M1, M2, or M3 connected thereto, as well as the associated TPIM. Past history of thermal loading of a given device may inform such an allocation as part of the applied costing function. For instance, if motor M1 (e.g., the electric traction motor 114 of
Control of the electrified powertrain 11 of
Additionally, the present teachings contemplate active real-time audio, visual, and/or haptic feedback to the operator to inform the operator of the present availability or lack thereof of entry into MPM. Enhanced performance and drive enjoyment are thus enabled while maintaining awareness of short term and long term component durability. These and other possible advantages will be readily apparent to those of ordinary skill in the art in view of the foregoing disclosure.
The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the appended claims. Moreover, this disclosure expressly includes combinations and sub-combinations of the elements and features presented above and below.
