Method for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device in a vehicle

Abstract

In various embodiments, a method for determining at least one piece of traffic flow information based on a state-of-charge profile (L) of an energy storage device in a vehicle is provided, wherein the traffic flow information is determined based on a comparison of a reference state-of-charge profile, which corresponds to an unaccelerated journey of the vehicle, with the current state-of-charge profile (L). Furthermore, a method for determining traffic flow information is provided, as well as a functional module for determining at least one piece of traffic flow information based on a state-of-charge profile (L) of an energy storage device in a vehicle.

Description

[0001] The present invention relates to a method for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device in a vehicle.

[0002] Methods are known from the prior art for determining the power demand on the drive system based on information available at the start of a journey in a hybrid or electric vehicle. This determination can utilize values ​​set by the driver before or at the start of the journey, such as the destination communicated to the navigation system, as well as values ​​derived from the driving history, such as the driver's driving behavior.

[0003] German patent application DE 19831487 C1 discloses, for example, a method for operating a hybrid vehicle with a traction battery and an electric drive unit, wherein a power requirement for a hybrid drive is determined depending on the distance to be traveled. Within the framework of this method, in addition to the battery's state of charge, environmental and traffic influences, such as the driving speed, the current accelerator and brake pedal positions, as well as future traffic situations, such as the route, speed limits, traffic light phases, inclines and declines, etc., are taken into account as input variables or information regarding the distance to be traveled, with the aim of optimizing operating strategies for hybrid vehicles.

[0004] From US patent 2015097512 A1, a method for operating a hybrid vehicle is known in which, based on knowledge of the upcoming route and the associated driving behavior, the vehicle calculates a target charging value for the battery, so that at the start of operation the vehicle can use regenerative braking and historical driving behavior to maximize battery charging during the journey.

[0005] Publication DE 102010055282 A1 discloses a method for operating a hybrid vehicle in which an operating mode of the hybrid vehicle is set depending on a detected and / or predicted traffic situation.

[0006] The aim of the present procedure is to determine at least one traffic flow information, in particular a probability of congestion, based on a state-of-charge profile of an energy storage device in a vehicle.

[0007] This problem is solved by means of the subject matter of the independent claims. Further preferred embodiments are found in the dependent claims.

[0008] The present invention is based on the finding that information about traffic flow can be derived by evaluating the state of charge of a high-voltage battery (HV battery) in a vehicle with at least partial electric drive. The method can be used particularly in mild hybrids, but is by no means limited to this type of vehicle drive and can therefore be used in principle in hybrid electric vehicles (HEVs) and hybrid plug-in hybrid vehicles (PHEVs).

[0009] This method is particularly useful during vehicle operating phases where the battery management system aims to maintain a relatively constant state of charge (SoC), for example, when driving on a highway or rural road without significant acceleration, i.e., at a relatively constant speed. Any deviations from a constant driving style due to braking, overtaking, or traffic jams directly lead to a change in the battery's state of charge. By analyzing the deviation of the state-of-charge profile (state-of-charge curve) from a reference profile that corresponds to essentially unaccelerated driving, the current traffic situation can be assessed, especially regarding the presence of a traffic jam.

[0010] According to the invention, a method for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device in a vehicle is provided, in which the traffic flow information is determined based on a comparison of a reference state-of-charge profile, which corresponds to an unaccelerated journey of the vehicle, with the current state-of-charge profile.

[0011] The shape of the reference state-of-charge profile can be essentially determined by a control method for the state of charge of the energy storage system. In particular, the shape of the reference state-of-charge profile can be determined by a control method that aims for a target state-of-charge value of the energy storage system. Common control methods result in a smooth sawtooth oscillation of the state-of-charge value around the target state-of-charge value. Deviations from driving at a constant speed or at least with negligible acceleration (both negative and positive) correspond to temporary deviations from the reference state-of-charge profile and can be detected by a corresponding comparison. Braking processes, which recuperatively charge the energy storage system, can lead to a larger positive gradient and / or a higher local maximum value in the state-of-charge profile.Similarly, increases in speed, during which, in the case of a hybrid drive, more energy is drawn from the energy storage system to support the combustion engine in generating propulsion, can lead to a larger negative gradient and / or a smaller local minimum value in the state-of-charge profile. In other words, the state-of-charge profile can be used to read a record of the vehicle's driving dynamics, from which traffic flow information is derived within the framework of the procedure described here.

[0012] The shape of the reference state-of-charge profile can be determined by simulation, taking into account the frequency and / or intensity of acceleration phases, and stored in the energy storage system's control unit. Alternatively or additionally, the state-of-charge profile can also be recorded during a steady, essentially unaccelerated drive, for example, with cruise control activated on a route without significant inclines or declines, and used as the reference state-of-charge profile. In principle, the reference state-of-charge profile reflects the influence of other consumers in the vehicle (e.g., lights, air conditioning, multimedia system), whose discharge potential of the energy storage system falls short of the discharge potential of the electric motor. Furthermore, the influence of the control method itself on the state-of-charge profile can be factored out using the reference state-of-charge profile.As already mentioned, even in the absence of energy transfers from the energy storage to the powertrain and from the powertrain and / or the (recuperative) braking system to the energy storage, the state of charge (SOC) of a mild hybrid fluctuates around a target value due to periodic charging and discharging by the energy storage controller.

[0013] According to further embodiments of the method, traffic flow information can be determined based on a comparison of a sample of the reference state-of-charge profile with a sample of the current state-of-charge profile. Within this comparison, for example, the frequency or frequency components in both state-of-charge profiles can be compared. From the deviations of the patterns, e.g., with regard to amplitudes and / or frequencies or frequency components (for this purpose, the state-of-charge profiles can be compared, for example, in the frequency domain), conclusions about the current vehicle status can be derived. A changed frequency, for example, indicates a change in the vehicle's state of charge.This is equivalent to a change in the frequency of the reversal points at which the control mechanism intervenes, either initiating regenerative charging (including regenerative charging) of the energy storage system at the lower state-of-charge limit and allowing normal discharge operation of the energy storage system at the upper state-of-charge limit, where regenerative energy inputs are, of course, permitted and desirable. If these points are closer together, this means that the energy intake or output is greater compared to driving without acceleration. From this, conclusions can be drawn about the number and intensity of events in which the vehicle's speed is reduced or increased. Based on this analysis, information about the current traffic flow can then be determined.For example, when a vehicle starts moving from a standstill, the electric motor has a relatively high energy demand because the combustion engine has a relatively poor efficiency in this range and is therefore supported by the electric motor, also to overcome any initial sluggishness of the vehicle or to achieve particularly agile acceleration. Consequently, stop-and-go traffic can be recognized by its specific signature in the state-of-charge profile of the vehicle involved, unlike stop-and-go traffic, where the vehicle, for example, repeatedly decelerates and accelerates at an average speed of 60 km / h.

[0014] According to further embodiments of the method, traffic flow information can be determined based on a comparison of slopes at the edges in the reference state-of-charge profile and in the current state-of-charge profile. The slope or gradient of the edges allows conclusions to be drawn about the degree of energy input into or output from the battery. This, in turn, allows conclusions to be drawn about the state of the traffic flow in which the vehicle is located.

[0015] According to further embodiments of the method, traffic flow information can be determined based on a comparison of the frequency and / or values ​​of local minima and / or maxima in the reference state-of-charge profile and in the current state-of-charge profile. An increase in the state-of-charge value above an upper limit or a drop below a lower limit, at which point the energy storage controller activates or deactivates active recharging of the energy storage system, can be attributed to a higher frequency and / or more intensive execution of braking events or (positive) acceleration events. This, too, allows conclusions to be drawn about the state of the traffic flow in which the vehicle is located.

[0016] According to further embodiments of the method, traffic flow information can additionally be determined based on the current gear selection and / or the current speed. Since fully electric vehicles nowadays mostly only have one or two forward gears, the rotational speed of the electric motor can also be used as information to determine the traffic flow information, in order to ascertain the speed range in which braking or (positive) acceleration processes take place.

[0017] According to further embodiments of the method, the energy storage device can be a high-voltage battery of a hybrid drive or a purely electric drive of the vehicle.

[0018] According to further embodiments of the method, the traffic flow information can correspond to a probability of congestion. For this purpose, a traffic flow indicator (e.g., a value between zero and one) can be generated based on the evaluation of the state-of-charge profile, indicating how smoothly or unimpeded the road traffic is in which the vehicle is moving. Furthermore, or alternatively, the traffic flow information can include data on the average free distance and / or the average speed and / or the frequency / duration of standstill times or speeds below a predetermined threshold (e.g., 30 km / h) due to congestion. Based on at least one of these data points, the traffic flow can be characterized.

[0019] According to further embodiments of the method, it can also include the transmission of traffic flow information to an external unit via wireless communication. The communication can be transmitted, for example, via a wireless mobile network to a central location, to which this information is transmitted by a large number of vehicles. From the totality of the individual traffic flow information received, the central location can determine a more precise information about the traffic flow in a specific area. Additionally or alternatively, the individual traffic flow information can be transmitted directly to other vehicles, for example, within a predetermined radius of the sending vehicle.This allows a vehicle to determine traffic flow information based on its own state-of-charge profile and taking into account at least one individual traffic flow information received from at least one other vehicle.

[0020] According to the invention, a method for determining traffic flow information is further provided, comprising receiving individual traffic flow information from at least two vehicles and determining the traffic flow information based on the received individual traffic flow information. The individual traffic flow information in each of the vehicles involved can be determined using the previously described method according to the invention for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device.

[0021] By analyzing the individual traffic flow information from different vehicles, these vehicles can be considered a fleet within a specific area, such as a section of highway or a rural road between two towns. Based on the traffic flow information transmitted by this fleet, the traffic flow in the relevant area can be monitored in real time and / or even predicted through intelligent data analysis.

[0022] According to the invention, a functional module for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device in a vehicle is further provided, wherein the functional module is coupled to or integrated into the energy storage control system and is configured to execute the previously described method for determining at least one traffic flow information based on a state-of-charge profile of an energy storage device.

[0023] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0024] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing. Fig. Figure 1 shows an example of a state-of-charge profile of a hybrid vehicle.

[0025] The inventive method for determining at least one traffic flow piece of information based on a state-of-charge profile of an energy storage device in a vehicle will be described below using the diagram in Fig. The charge state profile L shown in Figure 1 illustrates this. In the diagram, time t is plotted on the x-axis and the charge state (SOC) on the y-axis.

[0026] In the example scenario shown, the battery controller attempts to maintain the state of charge (SOC) of the high-voltage (HV) battery at a constant value, the setpoint S. This scenario can correspond, in particular, to the operation of an HV battery in a mild hybrid or a plug-in hybrid electric vehicle (PHEV) or hybrid electric vehicle (HEV) operating at the lower end of the battery's SOC operating range. Due to the controller's operating principle and / or technical implementation, the state of charge oscillates between an upper limit O and a lower limit U, such that its average value approximately corresponds to the setpoint S. Depending on the quality and complexity of the control loop, the amplitude of the state of charge as it oscillates around the setpoint S is a few percent of the setpoint S.

[0027] The in Fig.The charge state profile L shown is divided into three areas A, B, and C. In areas A and C, the control loop manages to maintain the charge state within the operating range, i.e., between the upper charge state limit O and a lower charge state limit U. Furthermore, the frequency of the charge state profile L does not change significantly in these areas. Areas A and C can be associated with predominantly steady-flowing traffic. The middle sawtooth wave in area C of the charge state profile L shows that excessive energy consumption occurred on the left flank, which can be attributed to a relatively strong (positive) acceleration event. The maximum reached by the middle sawtooth wave in area C lies above the upper charge state limit and can be attributed to a relatively strong braking event.Since the further course of the charge state profile in area C shows no significant abnormalities, it can be assumed that the vehicle is traveling at a constant, unaccelerated speed.

[0028] In the central region B, located between regions A and C, the state-of-charge profile is "downward-sloping." In other words, the controller is unable to maintain the state of charge at the target value S. In this region, increased energy output from the battery can be assumed, which can be attributed to a higher frequency of (positive) acceleration events. Furthermore, it is noticeable that the gradients in region B are smaller in magnitude on rising edges than on falling edges, with the gradients of the rising edges in region B roughly corresponding to the gradients of the rising edges in regions A and B. From this, it can be deduced that predominantly relatively strong (positive) acceleration events occurred in region B, but no braking processes that led to recuperation, which would have increased the gradient of the rising edges, at least in certain sections.Therefore, section B can be assigned to a segment of the vehicle's journey during which it accelerated relatively strongly without significant braking. Consequently, it can be assumed that during the average journey time B, the traffic flow was not disrupted or that the road occupancy was far below its traffic-carrying capacity. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 19831487 C1

[0003] US 2015097512 A1

[0004] DE 102010055282 A1

[0005]

Claims

[1] Method for determining at least one item of traffic flow information on the basis of a state of charge profile (L) of an energy storage device in a vehicle, wherein the traffic flow information is determined on the basis of a comparison of a reference state of charge profile, which corresponds to an unaccelerated travel of the vehicle, with the current state of charge profile (L). [2] Method according to claim 1, wherein the shape of the reference state of charge profile is substantially determined by a control method of the state of charge (SOC) of the energy storage device. [3] Method according to one of claims 1 or 2, wherein the traffic flow information is determined on the basis of a comparison of a pattern of the reference state of charge profile with a pattern of the current state of charge profile (L). [4] Method according to one of claims 1 to 3, wherein the traffic flow information is determined on the basis of a comparison of gradients at flanks in the reference state of charge profile and in the current state of charge profile (L). [5] Method according to one of claims 1 to 4, wherein the traffic flow information is determined on the basis of a comparison of a frequency and / or values of local minima and / or maxima in the reference state of charge profile and in the current state of charge profile (L). [6] Method according to one of claims 1 to 5, wherein the traffic flow information is additionally determined on the basis of the current gear selection and / or the current speed. [7] Method according to one of claims 1 to 6, wherein the energy storage device is a high-voltage battery of a hybrid drive or a purely electric drive of the vehicle. [8] Method according to one of claims 1 to 7, wherein the traffic flow information corresponds to a congestion probability. [9] A method according to any one of claims 1 to 8, wherein the method further comprises: Transmitting traffic flow information to a vehicle-external unit via wireless communication. [10] Method for determining traffic flow information, comprising the steps: Receiving individual traffic flow information from at least two vehicles, Determine traffic flow information based on the received individual traffic flow information. [11] Functional module for determining at least one item of traffic flow information on the basis of a state of charge profile (L) of an energy storage device in a vehicle, wherein the functional module is coupled to or integrated into the energy storage control system and is configured to carry out the method according to one of claims 1 to 9.

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