Patent Publication Number: US-2021188246-A1

Title: Supervisory genset control in range-extended electric vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Application No. 62/949,756, filed Dec. 18, 2019, the contents of which are hereby incorporated by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under DE-EE0007514 awarded by the Department of Energy. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to a system and methods for supervisory genset control in a range-extended electric vehicle. 
     BACKGROUND OF THE DISCLOSURE 
     A range-extended electric vehicle (REEV) generally includes a set of controls for determining a power demand from an operator, and then determining which power source will provide what amount of the desired power to meet the power demand of the operator. Typically, the set of controls includes system controls for determining the operator power demand and the genset power demand, and a genset control system for determining the speed target of the genset, which includes a range extender and/or a generator, and the torque demand for the range extender and/or the generator. However, this controls setup results in an undesired transient performance during sudden power demand changes and various uncertainties. In addition, this control setup does not take into consideration emissions during the transient performance, and the genset control resides in a hybrid system control module, and the system control communicates with the range extender and the generator separately, which makes it difficult to integrate a stand-alone genset to a 3 rd  party REEV. Thus, a control setup is needed that can handle sudden power demand changes without undesired transient performance, take emissions into consideration during its performance, and is capable of being integrated into other REEVs. 
     SUMMARY OF THE DISCLOSURE 
     In one embodiment of the present disclosure, a controls system for a range-extended electric vehicle is provided. The control system comprises an overall system control unit, an engine control module configured to control a range extender of the range-extended electric vehicle, power electronics configured to control a generator of the range-extended electric vehicle; and a supervisory control module coupled between the overall system control unit and the engine control module and the power electronics, where the supervisory control module is configured to receive information from the overall system control unit and provide commands to at least one of the engine control module and the power electronics. 
     In another embodiment of the present disclosure, a method for providing at least one command to at least one of a range extender and a generator of a range-extended electric vehicle is provided. The method comprises determining, by an overall system control unit, a driver power demand, providing, from the overall system control unit, the driver power demand and a desired operation mode to a supervisory control module, determining, by the supervisory control module, at least one of a target speed and a target torque for the at least one of the range extender and the generator, determining, by the supervisory control module, at least one command based on the at least one of the target speed and the target torque, and providing, from the supervisory control module, the at least one command to at least one of an engine control module for controlling the range extender and power electronics for controlling the generator. 
     In a further embodiment of the present disclosure, a method for determining commands for at least one of a range extender and a generator of a range-extended electric vehicle is provided. The method comprises simultaneously optimizing a trajectory based on at least one operation mode to provide at least one of a speed command and a torque command to the at least one of the range extender and the generator, and controlling the at least one of the speed command and the torque command based on information received from a dynamic genset model and at least one of an actual speed measurement and an actual torque measurement of at least one of the range extender and the generator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings, wherein: 
         FIG. 1  shows a diagram of an embodiment of a genset and a set of controls of the present disclosure, where the genset includes a range extender and a generator, and the set of controls comprises an overall system control unit, a supervisory control module, an engine control module (ECM), and power electronics; 
         FIG. 2  shows a diagram of an embodiment of a method of the present disclosure for provide commands to the range extender and the generator of  FIG. 1 ; 
         FIG. 3  shows a graphical diagram of a plurality of trajectories for getting from a current operating point to a subsequent operating point dependent on a desired mode of operation and/or method of optimization; 
         FIG. 4  shows a diagram of a map-based reference trajectory plus feedback speed tracking method of optimization of the present disclosure; 
         FIG. 5  shows a diagram of an online reference trajectory plus feedback speed tracking method of optimization of the present disclosure; and 
         FIG. 6  shows a diagram of a lumped online model-based trajectory method of optimization of the present disclosure. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplifications set out herein illustrate embodiments of the disclosure, in one form, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to  FIG. 1 , a range-extended electric vehicle (REEV) (not shown) generally includes an electric motor and/or traction motor (not shown), a genset  10  having a range extender  12  and a generator  14 , and a battery (not shown). Range extender  12  of genset  10  may be comprised of a variety of power producing devices, including but not limited to, a diesel engine, a gasoline engine, or a natural gas engine. In various embodiments, range extender  12  may be an internal combustion engine. The REEV generally further includes a set of controls  20  comprising an overall system control unit  22 , a supervisory control module  24 , an engine control module (ECM)  26  coupled to range extender  12 , and power electronics  28  coupled to generator  14 . 
     With reference to  FIGS. 2 and 3 , a general method  100  for providing commands to range extender  12  and/or generator  14  is provided. In general, overall system control unit  22  is first configured to determine a driver power demand at step  102  via a push pedal or other driver interface apparatus. From the determined power demand, a genset power demand is determined at step  104  via overall system control unit  22 . In various embodiments, overall system control unit  22  may further determine a battery power demand at step  104 . Once the driver power demand and the genset power demand are determined by overall system control unit  22 , overall system control unit  22  provides the genset power demand to supervisory control module  24 , and supervisory control module  24  determines a genset speed target and/or torque target at step  106 . At step  108 , supervisory control module  24  determines a desired speed and/or torque demand for range extender  12  and/or generator  14  from the genset speed or torque target determined by supervisory control module  24 , and provides said speed/torque demands to ECM  26  for controlling range extender  12  and/or power electronics  28  for controlling generator  14 . In various embodiments, steps  106  and  108  may be combined into a single step. For instance, when a lumped online model-based trajectory method of optimization is used (discussed further below), steps  106  and  108  are combined into a single step where online optimization is used to determine torque demands for range extender  12  and/or generator  14 . 
     In general, overall system control unit  22  is configured to determine how much power is needed from range extender  12  and/or generator  14  based on status information regarding the state of range extender  12  and generator  14  received from supervisory control module  24 . The status information may include fuel consumption, genset efficiency, actual power delivered, power capability (including static and dynamic power limits), range extender and generator actual states, range extender and/or generator speed and/or torque, generator current and/or voltage, diagnostics, and total energy estimation, among other various types of information. 
     Supervisory control module  24  is configured to receive target/command information from overall system control unit  20 , determine commands for range extender  12  and generator  14  based on said information, translate said commands for providing to ECM  26  and power electronics  28 , and provide said commands to ECM  26  for controlling range extender  12  and power electronics  28  for controlling generator  14 . The target/command information received by supervisory control module  24  may include a control mode command such as power control mode, voltage control mode or current control mode, a desired operation mode such as performance mode, emission (clean) mode, economy mode, or balanced mode, and/or control targets such as an overall power demand, a voltage target, and/or current target, among other various target/command information. Once the target/control information is received, supervisory control module  24  determines how to get from the current operating point to another operating point in order to meet the power demand. 
     Power electronics  28  and ECM  26  are configured to provide generator  14  and range extender  12  states and/or feedback information, respectively, to supervisory control module  24 , and receive commands from supervisory control module  24  for generator  14  and range extender  12 , respectively. The commands provided to generator  14  and/or range extender  12  typically includes commands for changing speed and/or torque of generator  14  and/or range extender  12 . 
     Referring now to  FIGS. 3-6 , methods for determining speed and/or torque demands for range extender  12  and/or generator  14 , and more specifically, methods for optimization of these demands will be described. The trajectory, or change in desired speed and/or torque demands, for getting from the current operating point to the next operating point is dependent on the desired mode of operation and/or the method of optimization (see  FIG. 3  showing how trajectories may change based on the different mode of operation and/or methods of optimization). For example, based on the desired mode of operation and/or the method of optimization, more speed and/or torque may be needed from range extender  12  than generator  14  or vice versa. The method of optimization used may include map-based reference trajectory plus feedback speed tracking, online reference trajectory optimization plus feedback speed tracking, or lumped online model-based trajectory optimization, among other methods of optimization. 
     With reference to  FIG. 4 , the map-based reference trajectory plus feedback speed tracking method of optimization  300  will be described. Map-based method of optimization  300  generally includes a map-based reference trajectory optimization section  302  and a feedback speed tracking section  304 . In various embodiments, both sections  302  and  304  are carried out by supervisory control module  24 . Map-based reference trajectory section  302  is configured to receive the power demand and desired operation mode from system control unit  22  and determine speed/torque references or desired values based on various lookup tables. These various lookup tables generally include predefined optimized genset trajectories based on different objectives where speed/torque reference(s)/desired values can be determined from these lookup tables based on the desired power demand and the desired operation mode provided. The determined speed/torque reference(s) are then provided to feedback speed tracking section  304 . 
     Feedback speed tracking section  304  is generally configured to correct deviations of the system and update the look up tables based on the information received. Feedback speed tracking section  304  generally includes a model-based feedforward control  310 , a first signal aggregator  312 , a model-based feedback control  314 , a second signal aggregator  316 , an adaptive uncertainties estimator  318 , and a third signal aggregator  320 . 
     Model-based feedforward control  310  is generally configured to receive the speed/torque reference(s) from map-based reference trajectory section  302  and estimated adaptive uncertainties or adjustments from adaptive uncertainties estimator  318  and provide a suggested speed and/or torque value to second signal aggregator  316 . Model-based feedforward control  310  handles the transient in the speed and torque profile, and calculates the suggested speed/torque commands based on both the speed/torque reference(s) and the estimated adaptive uncertainties. Model-based feedforward control  310  contains the dynamics of genset  10  either from physics-based modeling or data-based modeling. When control  310  receives the desired torque/speed targets, it will use the model information to automatically determine the corresponding commands. First signal aggregator  312  is generally configured to receive the speed/torque reference(s) from map-based reference trajectory section  302  and actual speed/torque from range extender  12  and generator  14 , and provide a difference between the speed/torque reference and the actual speed/torque readings to model-based feedback control  314 . 
     Model-based feedback control  314  is generally configured to receive a difference between the speed/torque reference and the actual speed/torque readings from first signal aggregator  312  and estimated adaptive uncertainties from adaptive uncertainties estimator  318 , and provide a corrective action to second signal aggregator  316 . Model-based feedback control  314  shares the same principle with model-based feedforward control  310  in that it contains the dynamics of genset  10 . However, model-based feedback  314  uses the difference between the torque/speed targets and the actual torque/speed feedback signal to determine the corresponding commands. 
     Second signal aggregator  316  is generally configured to receive a suggested speed/torque from model-based feedforward control  310  and a corrective action from model-based feedback control  314  and provide adjusted speed/torque commands to range extender  12  and generator  14 . Third signal aggregator  320  is generally configured to receive the speed/torque commands from second signal aggregator  316  and actual speed/torque from range extender  12 /generator  14  and provide this information to adaptive uncertainties estimator  318 . Adaptive uncertainties estimator  318  is generally configured to receive speed/torque commands and actual speed/torque from third signal aggregator  320  and provide estimated adaptive uncertainties and/or adjustments. Adaptive uncertainties estimator  318  handles slower drifts and degradation of the sensors or components and mismatches between the model and the physical system based on the command and actual range extender/generator feedback, by providing estimated adaptive uncertainties or adjustments for making corrections to the feedforward and feedback control accordingly. 
     Referring now to  FIG. 5 , the online reference trajectory plus feedback speed tracking method of optimization  400  will be described. Online reference method of optimization  400  generally includes an online reference trajectory optimization section  402  and a feedback speed tracking section  404 . In various embodiments, both sections  402  and  404  are carried out by supervisory control module  24 . Online reference trajectory section  402  is configured to receive the power demand and desired operation mode from system control unit  22  and determine speed/torque references or desired values based on an online optimization algorithm which contains models of the actual system. The model of the actual system generally includes the specific model of generator  14  and range extender  12 , and knows the efficient operating zones for each. The optimization algorithm then calculates the optimal commands with the power demands from system control unit  22  and the desired operational mode. The speed/torque reference(s) determined from the online optimization algorithm are then provided to feedback speed tracking section  404  similarly to method of optimization  300 . Feedback speed tracking section  404  is configured to operate in the same manner as feedback speed tracking section  304 , with section  404  receiving the speed/torque reference(s) from online reference trajectory section  402 . 
     With reference to  FIG. 6 , the lumped online model-based trajectory method of optimization  500  will be described. Lumped online method of optimization  500  generally includes a single optimization and control algorithm  502  and a dynamic genset model  504 . Lumped online method of optimization  500  uses single optimization and control algorithm  502 , to simultaneously optimize the desired torque and/or speed values based on different objectives or operation modes to provide speed and torque commands to generator  14  and range extender  12 , and control torque of generator  14  and range extender  12  based on information from dynamic genset model  504  and real time actual measurements of speed and torque of generator  14  and range extender  12 . In other words, the single optimal control algorithm combines the trajectory section and the feedback sections of the previously described methods of optimization. 
     In various embodiments, the method of optimization may also influence air handling control of range extender  12  when high performance is required (i.e., the method may prime the air handling system to decline power faster) and/or thermal management of an aftertreatment control of range extender  12  when low emissions are desired (i.e., based on history/probability of power demand, active thermal management of the aftertreatment system may be scheduled to allow faster heat generation and less fuel consumption during the active thermal management). Furthermore, the method of optimization may also predict the power demand based on historical data and/or statistics of the power demand to assist the method of optimization. 
     While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications. 
     Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. The scope is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B or C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. 
     In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. § 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.