CONTROLLING A VEHICLE BATTERY BASED ON IDLE VOLTAGE

Abstract

Voltage data from a traction battery is written to a memory for a predefined period in response to the opening of contactors electrically connected between the traction battery and an electric machine. Processing of the voltage data begins before the end of the predefined period to generate an open-circuit voltage for the traction battery. The traction battery is then charged or discharged according to power limits based on this open-circuit voltage.

Description

AREA OF TECHNOLOGY

[0001] The present disclosure relates generally to the control of a battery for an electrified vehicle. In particular, the present disclosure relates to a system and a method for controlling the battery based on an open-circuit voltage (OCV). GENERAL STATE OF THE ART

[0002] An electrified vehicle (EV) relies on one or more traction batteries to provide power to electric motors that propel the EV. One or more operating characteristics of the battery pack, such as power limits and state of charge (SOC), can be estimated to control the charging and discharging process of the traction batteries. SUMMARY

[0003] A vehicle includes a traction battery, an electric machine, and one or more controllers that, in response to a disconnection of the traction battery from the electric machine, record voltage data about the traction battery for a predefined period, so that the voltage data for the predefined period, but not immediately after the predefined period, is written to a memory, and before the predefined period expires, initiate processing of the voltage data, so that the load on a processor performing the processing increases before the predefined period ends.

[0004] A power system for a vehicle includes one or more controllers that, while the vehicle is parked and in a mode with the ignition off, write voltage data associated with a vehicle battery to a memory for a predefined period and initiate processing of the voltage data before the end of the predefined period, so that the processing ends after the predefined period and the load on a processor performing the processing increases before the end of the predefined period and decreases after the end of the predefined period.

[0005] A procedure for a vehicle involves opening contactors electrically connected between a traction battery and an electric machine, writing voltage data about the traction battery to a memory for a predefined period in response to the opening, initiating processing of the voltage data before the end of the predefined period to generate an open-circuit voltage for the traction battery, and charging or discharging the traction battery according to power limits based on the open-circuit voltage. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 illustrates an exemplary block topology of an electrified vehicle, illustrating the drive and energy storage components of an embodiment of the present disclosure. Fig. Figure 2 illustrates a flowchart of an open-circuit voltage estimation process of an embodiment of the present disclosure. Fig. Figure 3 illustrates a flowchart of an open-circuit voltage estimation process of another embodiment of the present disclosure. Fig. Figure 4 illustrates a flowchart of a process for calculating a candidate β of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0006] This document describes embodiments. However, it is understood that the disclosed embodiments are merely examples and that other embodiments may take different and alternative forms. The figures are not necessarily to scale. Some features may be enlarged or reduced to show details of specific components. Therefore, specific design and functional details disclosed in this document are not to be interpreted as limiting, but merely as a representative basis for teaching the person skilled in the art.

[0007] Various features illustrated and described with respect to any one of the figures can be combined with features illustrated in one or more other figures to create embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications.

[0008] However, various combinations and modifications of the features that are consistent with the teachings of this revelation may be desirable for specific applications or implementations.

[0009] The present disclosure proposes, among other things, a system and a method for controlling a traction battery of an EV based on an open-circuit voltage.

[0010] Fig. Figure 1 illustrates a plug-in hybrid electric vehicle (PHEV). A plug-in hybrid electric vehicle 112 can include one or more electric machines (electric motors) 114 mechanically coupled to a hybrid transmission 116. The electric machines 114 can operate as motors or generators. Additionally, the hybrid transmission 116 is mechanically coupled to an internal combustion engine 118. The hybrid transmission 116 is also mechanically coupled to a drive shaft 120, which is mechanically coupled to the wheels 122. The electric machines 114 can provide propulsion and deceleration capabilities when the internal combustion engine 118 is switched on or off. The electric machines 114 can also function as generators and provide fuel efficiency benefits by recovering energy that would otherwise be lost as heat in the friction braking system.The electric machines 114 can also reduce vehicle emissions by enabling the combustion engine 118 to operate at more efficient speeds and by enabling the hybrid electric vehicle 112 to operate in electric mode, in which the combustion engine 118 is switched off under certain conditions.

[0011] A traction battery or battery pack 124 stores energy that can be used by the electric machines 114. A vehicle battery pack 124 can include a plurality of battery cells 123 connected in series and / or parallel to provide a high-voltage direct current (DC) output. In one example, the battery cells 123 can be permanently attached to a housing of the traction battery 124 and not removable. In an alternative example, the battery cells 123 can be individually removable to allow the user to replace one or more cells. It should be noted that the term "battery cell" is used in this disclosure as a generic term and can refer to a single battery cell, an arrangement of battery cells connected in series, or the like.

[0012] The traction battery 124 can be electrically coupled to one or more battery electric control modules (BECMs) 125. The BECM 125 can be equipped with one or more processors, memory, and software applications configured to monitor and control various operations of the traction battery 124. The traction battery 124 can also be electrically coupled to one or more power electronics modules 126. The power electronics module 126 can also be referred to as a power inverter. One or more contactors 127 can isolate the traction battery 124 and the BECM 125 from other components when open, and couple the traction battery 124 and the BECM 125 to other components when closed. The contactors 127 can, for example, be operated by the BECM 125.The power electronics module 126 can also be electrically coupled to the electric machines 114 and provide the capability for bidirectional energy transfer between the traction battery 124 and the electric machines 114. For example, a traction battery 124 can provide a DC voltage, while the electric machines 114 can be operated using three-phase AC current. The power electronics module 126 can convert the DC voltage into three-phase AC current for use by the electric machine 114. In a regeneration mode, the power electronics module 126 can convert the three-phase AC current from the electric machines 114, which function as generators, into the DC voltage compatible with the traction battery 124. The description herein applies equally to a purely electric vehicle.In a purely electric vehicle, the hybrid transmission 116 may be a manual transmission connected to the electric machine 114, and the motor 118 may not be present.

[0013] In addition to providing propulsion energy, the traction battery 124 can supply energy to other electrical vehicle systems. A vehicle can include a DC / DC converter module 128, which converts the high-voltage DC output of the traction battery 124 into a low-voltage DC supply compatible with other low-voltage consumers in the vehicle. An output of the DC / DC converter module 128 can be electrically coupled to an auxiliary battery 130 (e.g., a 12 V battery).

[0014] The vehicle 112 can be a battery electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV) in which the traction battery 124 can be charged by an external power source 136. The external power source 136 can be a connection to a wall socket. The external power source 136 can be an electrical power distribution network or grid, such as that provided by an energy utility. The external power source 136 can be electrically connected to an electric vehicle supply equipment (EVSE) 138. The EVSE 138 can provide circuitry and controls to manage the transfer of energy between the power source 136 and the vehicle 112. The external power source 136 can provide DC or AC electrical power to the EVSE 138. The EVSE 138 can have a charging plug 140 for insertion into a charging port 134 of the vehicle 112.The charging port 134 can be any type of connector configured to transfer power from the EVSE 138 to the vehicle 112. The charging port 134 can be electrically coupled to a charging device or an onboard power converter module 132. The power converter module 132 can condition the power supplied by the EVSE 138 to provide the traction battery 124 with the correct voltage and current levels. The power converter module 132 can interface with the EVSE 138 to coordinate the supply of power to the vehicle 112. The EVSE connector 140 can have pins that mate with corresponding recesses in the charging port 134. Alternatively, various components described as electrically coupled can transfer power using wireless inductive coupling.

[0015] One or more electrical loads 146 can be connected to the high-voltage bus. The electrical loads 146 can have an associated controller which may operate and control them. Examples of electrical loads 146 include a heating module, an air conditioning module, or the like.

[0016] The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (e.g., Controller Area Network (CAN)) or via separate conductors. A system controller 150 may be present to coordinate the operation of the various components. It should be noted that the system controller 150 is used as a general term and may include one or more control devices configured to perform various operations as described in this disclosure. For example, the system controller 150 may be programmed to enable a powertrain control function to operate the powertrain of the vehicle 112. The system controller 150 may also be programmed to perform a telecommunications function with various instances (e.g., a server) over a wireless network (e.g., a mobile network).to enable a mobile network).

[0017] The traction battery 124 can further be equipped with one or more sensors 152 configured to measure one or more properties of the battery cells, including, but not limited to, electrical current, voltage, temperature, or the like. The BECM 125 can be configured to communicate with the sensors 152 to receive and process the data measurements.

[0018] In general, to manage the vehicle's traction battery 124, the vehicle system needs to know the state of charge (SOC) of the battery pack in order to estimate the battery pack's performance / power limit. For most battery chemical compositions, the SOC is estimated based on the battery pack's open-circuit voltage (OCV), which is the voltage of the battery pack when at rest. In a non-restrictive example, the OCV in hybrid electric vehicles (HEVs), where battery cell sizes are typically around five (5) ampere-hours, may stabilize within 30 minutes, but may take longer in colder temperatures.In particular, stabilization occurs when the active material is evenly distributed (by diffusion) across the thickness of an electrode, and the time required to achieve stabilization can be referred to as the equilibrium time for the battery cell. Battery charging and discharging reactions occur at the electrode surface. As battery cells become larger (e.g., their size is increased), the electrodes tend to become thicker, and thus the equilibrium time can increase. In some cases, it can take several hours for the OCV to stabilize.

[0019] In various situations, it can be difficult for vehicle 112 to remain stationary (i.e., neither charging nor discharging) for such long periods of inactivity. For example, in one situation, vehicle 112 may only be able to stop for a short time (e.g., less than 1 hour) before restarting. In another example, vehicle 112 may stop at a charging station for a few minutes for a fast charge.

[0020] Furthermore, the number of battery cells used in the traction battery can also influence the detection of the open circuit voltage (OCV) that can be measured for each battery cell. In particular, some traction batteries may contain around 100 cells in series, and as EVs move towards systems with higher electrical power (e.g., 800 V to 1200 V), the number of battery cells can double or even triple, thereby increasing the computational demands on the vehicle system.

[0021] The present disclosure proposes a vehicle system configured to operate the charging and discharging of the traction battery 124 based on an estimated OCV of one or more battery cells 123. In particular, the BECM 125 can estimate the OCV using voltage measurements, a temperature measurement, and a decay parameter that depends on the voltages since a last shutdown of the traction battery 124 and is detected using a selected relaxation time and an iterative estimation of a subparameter of the decay parameter.

[0022] Additionally, the BECM 125 can perform OCV estimation before all data has been collected. Unlike a conventional approach where OCV estimation only begins after all data has been collected, this disclosure proposes a system and a method that perform OCV estimation in parallel with data collection. In other words, the BECM 125 can start OCV estimation as soon as some data has been collected and perform the OCV estimation in parallel with the process while the rest of the battery data is being collected. In this way, the overall processing task of OCV estimation can be more evenly distributed over a longer period, thereby reducing the peak load on the BECM 125. The processor utilization can thus increase before the predefined period during which data is collected ends and decrease after the predefined period ends.In a non-restrictive example, the OCV for each battery cell 123 can be estimated and then aggregated to determine the OCV for the traction battery 124. Using the estimated OCV, the vehicle system (e.g., the BECM 125 and / or the system controller 150) can, among other actions (e.g., outputting a SOH), estimate a SOC, provide available energy at the start of a driving cycle used to predict vehicle driving range, and / or provide a power limit estimate.

[0023] In one example, the BECM 125 can be configured to estimate the OCV based on voltages measured by sensors 152 after a last shutdown of the vehicle 112, and a decay parameter that depends on the voltages and the duration since the last shutdown. Specifically, the BECM 125 can estimate the OCV for a battery cell 123 using the following equation: V=VOCV+βe−kt where V denotes the voltage of the battery cell 123 measured by the sensors 152 and βe−kt represents a decay parameter which is assigned to battery cell 123.

[0024] The decay parameter can be associated with a non-linear correlation with the voltage such that, after vehicle 112 is switched off, the rate of change of the voltage is not constant over time. As reflected in equation (1), the decay parameter can characterize the decaying voltage using an exponential parameter involving a square root of the duration and may also include a coefficient and a constant that depend on the voltages and the battery temperature. In the example shown in equation (1), the decay parameter includes subparameters such as β, k, and t. β denotes a coefficient related to state of charge (SOC), temperature, and the magnitude of the current before the contactors open; k denotes a time constant related to a diffusion coefficient in the electrodes and an Arrhenius relationship (i.e., k = Ae). -Ea / RT ) can follow; and t denotes time.

[0025] In particular, β can be calculated using stresses at time t and can be done with reference to time = 0 (i.e., β t ) are defined as the following equation (2): βt=V(t)−V(0)e−k*t−1 where V(t) is a voltage measurement at time t and V(0) is the voltage measured at time t=0 seconds. In particular, when t = 0, equation (1) becomes V(0) = V OCV + β, and therefore V OCV = V(0) - β. By replacing V OCV In equation (1) by “V(0) - β”, β is then represented by equation (2).

[0026] In a non-restrictive example, equation (3) represents β 60sec Ready below: β60sec=V(t=60)−V(0)e−k*60−1

[0027] The sign of β depends on the direction of the current shortly before the traction battery 124 is disconnected from the vehicle 112 via the main contactor 127. That is, if the traction battery 124 was (predominantly) discharged shortly before disconnection, the sign of β is negative, indicating that the voltage is lower than the OCV (open circuit voltage). If the battery pack 124 was (predominantly) charged, the sign of β is positive, indicating that the voltage is higher than the OCV.

[0028] In some examples, the decay parameter, and in particular β and k, are estimated using complex regression models based on stress measurements taken for a selected duration, such as one minute (i.e., 60 seconds). However, such estimation operations can require significant processing power from the BECM 125.

[0029] As described in detail in this paper, k can be defined in terms of β. β can in turn be determined using a selected relaxation time (t). RELAX ) from a variety of calibrated relaxation times and by comparing the predicted β (i.e., β PRED ) over a range of candidate β (β CAND ) can be estimated. For example, a voltage measurement at a relaxation time T RELAX , which occurs some time after the vehicle is switched off, is relatively accurate and smaller than a voltage sensor error (V SE ) (Error band) (e.g. t = t RELAX ), |V(t RELAX ) - OCV| ≤ V SE, or equivalent. In one embodiment, the relaxation time can be a predetermined fixed period. Additionally or alternatively, the relaxation time can be estimated based on the temperature of the battery pack 106, an absolute delta voltage (i.e., an absolute change in voltage) estimated using at least a subset of the measured voltages, and relaxation time correlation data that map selected inputs (e.g., the temperature and the absolute delta voltage) to associated relaxation times. In a non-restrictive example, the relaxation correlation data are provided as one or more lookup tables.

[0030] By defining time as the relaxation time in equation (2), k can be dependent on β. CAND V SE and the relaxation time (t RELAX ) expressed as provided in equation (4). k=ln[vSEβcand]2tRELAX

[0031] With reference to Fig. Figure 2 illustrates an exemplary OCV estimation process of an embodiment of the present disclosure. Further reference is made to Fig. 1. Process 200 can be implemented via one or more components of the vehicle 112. For example, process 200 can be implemented via the BECM 125 individually. Alternatively, process 200 can be implemented via the BECM 125 in combination with other components (e.g., the control unit 150) of the vehicle 112. For the sake of simplicity, the following description is set out with reference to the BECM 125, although the present disclosure is not limited to it. As detailed in this document, the BECM 125 estimates the OCV of the battery cells 123 by summing voltages measured for a predefined duration after a final shutdown of the vehicle 112 and a decay parameter. As discussed above, the decay parameter incorporates a variety of subcomponents obtainable using the equations above.The BECM 125 (and / or the control unit 150) can be configured to charge and discharge the traction battery using power limits defined by the estimated OCV when the vehicle 112 is switched on.

[0032] During process 202, the BECM 125 performs data measurements and writes them to memory for a fixed, predefined duration after shutdown to collect battery data indicating the conditions of one or more battery cells. The battery data can include various entries. For example, the battery data can include a variety of voltages and a variety of temperatures (T) of one or more battery cells 123 at different times during the duration.

[0033] Specifically, when the BECM 125 receives a shutdown request from the control unit 150 to electrically disconnect the traction battery 124 from the electric machine 114, the contactor 127 opens and the sensors 152 measure the voltage for the battery cells 123 for a selected duration (e.g., 60 seconds) and then interrupt the measurement. In one example, the duration is shorter than a stabilization time to allow the active material of each of the battery cells 123 to distribute evenly across one electrode of the battery cell 123. The cell temperature can be measured simultaneously with the voltage measurement. Alternatively, the temperature can be measured only occasionally at the beginning and / or end of the selected duration after the contactor 210 has opened, as continuous temperature data measurements may not be necessary to perform the OCV estimation.

[0034] In process 204, the BECM 125 determines whether the traction battery 124 was substantially charged or discharged before shutdown. Specifically, the BECM 125 calculates a variety of delta voltages ΔV to assess whether the voltage has substantially decreased or increased since the vehicle 112 was shut down. In the present restrictive example, the BECM 125 calculates three delta voltage values ​​ΔV1, ΔV2, and ΔVD using ΔV1 = V(t1) - V(0), ΔV2 = V(t2) - V(0), and ΔVD = IV(t1). D )-V(0)|, where: V(t D) is the voltage measured at the end of the duration; V(t1) is the voltage measured at time t1, where t1 is a time between t0 and the duration (e.g., if the duration is 60 seconds, t1 can be 20 seconds); where t2 is a time between t1 and the duration (e.g., if the duration is 60 seconds and t1 is 20 seconds, t2 can be 40 seconds); and V(0) is the voltage measured at t0 when the EV 100 is switched off.

[0035] During process 206, the BECM 125 determines whether the voltage is in relaxation, or in other words, whether the measured voltage is the OCV. Specifically, during process 206, the BECM 125 determines whether the ΔVD is less than a voltage delta threshold value (V). threshold ) or is equal to this (i.e., |V(t) D )-V(0)| ≤ V thresholdIf this is the case, the BECM 125 estimates the OCV, for example, by averaging the voltage measured at t1 for battery cells 123. This can occur in various scenarios, such as when the vehicle 112 has been switched off for a long time (e.g., a few hours) and the battery cells have fully recovered, the vehicle 112 is then switched on for a few minutes and then switched off again without any significant charge or discharge. In such cases, the brief switching on of the vehicle 112 may only slightly affect the OCV of battery cells 123, and the measured voltage can indicate the OCV. The voltage delta threshold can be selected to detect a significant voltage rise or fall using the voltage measured over the duration. In a non-restrictive example, the voltage delta threshold can be set to 4*V. SE be provided.

[0036] If the answer for process 206 is yes, i.e., ΔVD ≤ V- threshold If the voltage is in relaxation, process 200 proceeds to process 208, and the BECM estimates the OCV using the measured cell voltage. Otherwise, if the voltage is not in relaxation (i.e., ΔVD > V), the process continues. threshold ), the BECM 125 must determine whether the EV 100 was charged or discharged before shutdown in order to determine the sign of the decay parameter.

[0037] In process 210, the BECM 125 determines whether the delta voltage values ​​are greater than zero (i.e., ΔV1 > 0 and ΔV2 > 0). If both delta voltage values ​​are greater than zero, the BECM 125 determines that the vehicle 112 was discharged before shutdown. Therefore, in process 212, the BECM 125 establishes a discharge candidate range for β at a defined iteration step size. Specifically, in response to the detection that the battery pack 106 was discharged before the last shutdown, the BECM 125 can use a subparameter candidate range of values ​​for β for iterative estimation. As described above, β is a negative value if the vehicle 112 was discharged. The BECM sets the β-candidate area to a discharge area, where the β-candidate area is defined as V(0) - OCV(Full_SOC) ≤ β CAND≤ 0 is provided, where OCV(Full_SOC) is the OCV when the SOC is at 100%, which can be defined and stored by the BECM 125, and V(0) is the voltage measured at a time of zero t0.

[0038] If the answer at process 210 is no, indicating that the traction battery 124 was not discharged before shutdown, process 200 proceeds to process 214 to determine if both delta voltage values ​​are less than zero (i.e., ΔV1 < 0 and ΔV2 < 0). If both delta voltage values ​​are less than zero, the BECM 125 determines that the vehicle 112 was charged before shutdown. Therefore, at process 216, the BECM 125 sets a charge candidate range for β at a defined iteration step size. In particular, in response to the detection that the battery pack 106 was charged before the last shutdown, the BECM 125 can use a subparameter candidate range of values ​​for β for iterative estimation. As described above, β is a positive value if the vehicle 112 was charged. The BECM sets the β-candidate space to a loading area, where the β-candidate space is defined as 0 ≤ β CAND≤ V(0) - OCV(Empty_SOC) is provided, where OCV(Empty_SOC) is the OCV when the SOC is at 0%, which can be defined and stored by the BECM 125, and V(0) is the voltage measured at a time of zero t0.

[0039] Otherwise, if the BECM 125 is unable to determine either a load or an unload, process 200 will end at operation 220 without determining the OCV.

[0040] However, if process 200 arrives at either operation 212 or 216, the process moves to operation 218 to carry out process 300.

[0041] With reference to Fig. Figure 3 illustrates an exemplary OCV estimation process 300 of an embodiment of the present disclosure. It should be noted that, although process 300 is described following process 200, the present disclosure is not limited to it, and both processes 200 and 300 can be implemented independently via one or more components of the vehicle system. Similarly, for the sake of simplicity, the following description is set forth with reference to BECM 125, although the present disclosure is not limited to it.

[0042] In process 302, in response to detecting that the vehicle has been switched off, the BECM 125 measures the battery data associated with one or more battery cells 123 at time zero t0. Time zero t0 can be defined as the time at which the main contactor 127 is open, thus electrically disconnecting the traction battery 124 from the vehicle 112. As discussed above, the battery data can include various entries. The battery data includes the voltage of battery cell 123 at time zero V(0) across sensor 152. V(0) can be used as a reference voltage against which one or more successively measured voltages are compared to calculate various parameters. Additionally, the battery data can also include a temperature of battery cell 123, although the temperature data is not required in this example but is optional.

[0043] The BECM 125 can be configured to perform battery data measurements at a variety of predefined, sequential time indices to facilitate OCV estimation. In operation 304, upon detecting an initial time index t1 after reaching time zero t0, the BECM 125 measures battery data, including cell voltage V(t1), along with other battery data entries, if applicable. The time indices can be predefined and selected based on duration. For example, if the duration is 60 seconds, the initial time index t1 can be 20 seconds (and the second time index can be between 20 and 60 seconds).

[0044] Once the voltage has been reached at the first time index V(t1), the BECM 125 calculates the candidate β at process 306. CAND using V(t1). The detailed process for calculating the candidate β CANDThe first time index t1 (as well as all subsequent time indices) is in Fig. 4 illustrates.

[0045] With reference to Fig. 4 is an exemplary process 400 for calculating the candidate β CAND illustrated at various time indices of an embodiment of the present disclosure. With further reference to Fig. 3 The following description is given mainly with reference to procedure 306 for calculating the candidate β. CAND to the first time index t1; moreover, process 400 is essentially applied to calculating the candidate β using the same principle. CAND applicable to other time indices.

[0046] In process 402, the BECM 125 sets a value for a predicted β (β PRED) is set to the minimum possible value of β, which is defined by the β candidate region according to procedure 212 or 216, which are described above. For example, for the discharge region β PRED = V(0) - OCV(Full_SOC) and for the charging area β PRED = 0 V.

[0047] In operation 404, the BECM calculates 125 using β PRED a candidate k CAND In a non-restrictive example, the candidate k CAND The relaxation time t can be calculated using equation (4). RELAXThe function used in equation (4) can be detected or selected using relaxation time correlation data with inputs including a temperature and an absolute delta voltage estimated using at least one section of the measured voltages (e.g., ΔVD), as discussed above. In one example, the temperature and voltage measurements used are taken at approximately the same time, which can be determined using a timestamp associated with the measurements.

[0048] In process 406, the BECM 125 estimates the β-candidate at a first time index (β CAND_t1 ) using candidate k CAND and the voltage measurements assigned to the first time index. In the present example, the BECM 125 estimates the candidate β. CANDindependent of a first time index. In particular, only the battery data assigned to the first time index t1 are currently available, since process 400 is used to estimate the candidate β. CAND The first time index t1 begins immediately after the battery data for t1 is measured and before any subsequent time index is reached. The BECM 125 uses the following equation to determine the candidate β. CAND to a selected time index (e.g. β) CAND_t1 ) to determine, where V(t) is the voltage measured at that time and t is the time index (e.g. t1). βCAND_t=V(t)−V(0)e−kCAND*t−1

[0049] In process 408, the BECM 125 determines whether the predicted β PRED greater than a maximum possible value of β (i.e., β) MAX), which is defined by, or equal to, the β-candidate region in operation 212 or 216. For example, for the discharge region, the maximum possible value of β is zero, and for the load region, the maximum possible value of β is V(0) - OCV(Empty_SOC).

[0050] If the predicted β PRED If β is not greater than or equal to the maximum possible value, process 400 transitions to operation 410 and increments BECM 125 β. PREDBased on the iteration step size, the BECM 125 iteratively increments the predicted β value based on a selected step size to estimate β candidates at the time indices across the β candidate range. In a non-restrictive example, the step size is set within a range of 1 to 10 mV. A small iteration step size provides a more refined evaluation of β but also increases the computational load compared to a larger iteration step size.

[0051] If the predicted β PRED If β is greater than the maximum possible value, indicating that all possible options within the range have been processed, process 400 moves to operation 412 and BECM 125 stores the various predicted β values. PRED and the candidate β CANDonboard memory for future use. As discussed above, processing is performed individually (e.g., in parallel) for each time index t. Thus, when processing for a preceding time index (e.g., t1) is complete, the process for a subsequent time index (e.g., t2, t3..., t) can begin. n ) has not yet been completed (or even started). In one example, the predicted β PRED It may not be selected until processing for all time indices is complete.

[0052] With renewed reference to the with reference to Fig. In process 300, which is illustrated, the BECM 125 measures this at operation 308 in response to a subsequent time index t. NEXT Battery data was reached at t NEXT The battery data includes the readings from sensor 152 at t NEXTmeasured voltage. Additionally, the battery data can include the cell temperature at t. NEXT include.

[0053] In process 310, the BECM 125 processes the data at t NEXT collected battery data to identify the appropriate candidate β CAND using process 400, essentially in the same manner as discussed above with reference to process 306. Processes 308 and 310 can be performed in parallel with process 306. In other words, if the battery data for the subsequent time index t NEXT Measurements are being taken and data processing is being carried out, data processing for the previous time index is being carried out in parallel or has been completed.

[0054] As discussed above, a variety of time indices after the time of zero t0 can be used to predict β. PREDto determine. In process 312, BECM 125 determines that the last time index t LAST The time was reached and corresponding battery data was measured. In one example, the last time index corresponds to the end of the predefined duration t. D After the vehicle 112 is switched off, if the current time index is not the last time index, indicating that further predefined time indices are to follow, the process returns to operation 308.

[0055] Otherwise, if the last time index has been reached and the BECM 125 currently displays the last time index t LASTOnce the data has been processed or the processing is complete, the process proceeds to operation 314. In operation 314, the BECM 125 determines whether the measured voltage is the OCV, similar to operation 208 discussed above. The BECM 125 determines whether the ΔVD, which is the difference between the start (e.g., t0) and end (e.g., VD) of the predefined duration, is greater than a voltage delta threshold (V). threshold ) (e.g. | V(t) D )-V(0)| > V threshold In one example, the β-processing described in Process 300 is only applicable if the ΔVD is more than four times greater than the signal-to-noise ratio of the sensor accuracy (i.e., ΔVD > 4*V). SE ). In one example, if the sensor accuracy is 1.5 mV, the ΔVD must be greater than 6 mV (i.e., 4 * 1.5 mV) for process 300 to be applicable.

[0056] If the above condition is not met, process 300 terminates at operation 316 and the BECM estimates the OCV using the measured cell voltage. Otherwise, process 300 proceeds to operation 318 and the BECM 125 estimates a difference between the candidate β CAND-t at different time indices. In general, β should be constant, and therefore the smaller the difference between β CAND-t The more accurate the candidate β is, the more accurate the candidate β is. CAND compared to a true β in OCV. In a non-restrictive example, BECM 125 calculates a percentage error or percentage difference (i.e., %β). DIFF ) using the following equation. %βDIFF=|((βCAND_t_prior−βCAND_t_next)βCAND_t_prior)| where β CAND_t prior the candidate β CAND to a previous time index (e.g. t1) and β CAND_t_next the candidate β CAND to a subsequent time index (e.g. t1, t2 or tD ). The preceding time index t PRIOR and the subsequent time index t NEXT They do not have to be adjacent to each other. In other words, there can be one or more time indices that are located between the preceding time index t. PRIOR and the following time index t NEXT are located, which are represented in equation (6).

[0057] In process 320, the BECM 125 selects the value of β as the value of candidate β. CAND from the one with the smallest %β DIFF exhibits. For example, the BECM 125 uses the value of β. CAND-t , which has the lowest %β DIPP aufweist , as the value of β. In an example, among all β search values, there may be a value that gives the most accurate estimate of the OCV and is between β CAND_tx and β CAND_ty lies, where t X and t Y different time indices. Accordingly, the BECM 125 can measure the β-value between β CAND_tx and β CAND_tydetermining using various techniques, such as interpolation, without being limited to them.

[0058] In process 322, the BECM 125 estimates the OCV using OCV = V(0) - β. With the OCV, the BMM 132 is configured to estimate an initial state of charge of the battery pack based on the estimated OCV, with the power limits being partly defined by the initial state of charge.

[0059] In process 324, the BECM 125 estimates the performance of the traction battery 124 based on the OCV and performs vehicle operations, such as charging and discharging, accordingly.

[0060] The algorithms, methods, or processes disclosed in this document can be supplied to or implemented by a computer, controller, or processing device, which may include any dedicated electronic control unit or programmable electronic control unit. Furthermore, the algorithms, methods, or processes can be stored in many forms as data and instructions executable by a computer or controller, including, but not limited to, information permanently stored on non-writable storage media such as read-only storage devices, and information modifiably stored on writable storage media such as compact discs, random-access storage devices, or other magnetic and optical media. The algorithms, methods, or processes can also be implemented in software-executable objects.

[0061] Alternatively, the algorithms, methods or processes can be implemented wholly or partially using suitable hardware components, such as application-specific integrated circuits, field-programmable gate arrays, state machines or other hardware components or devices, or a combination of firmware, hardware and software components.

[0062] Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The terms used in the description are descriptive rather than limiting, and it is understood that various modifications may be made without altering the essence and scope of the disclosure. The terms processor and processors may be interchanged in this document, as may the terms controller and controllers.

[0063] As previously described, the features of different embodiments can be combined to form further embodiments of the invention, which may not be expressly described or illustrated. Although various embodiments may have been described in such a way that they offer advantages or are preferred over other embodiments or implementations according to the prior art with respect to one or more desired properties, the person skilled in the art understands that compromises may be made with respect to one or more features or properties in order to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, among others, strength, durability, marketability, appearance, footprint, size, maintainability, weight, manufacturability, ease of assembly, etc.Accordingly, embodiments that are described as less desirable than other embodiments or implementations according to the prior art with regard to one or more properties are not outside the scope of the disclosure and may be desirable for specific applications.

Claims

[1] Vehicle comprising the following: a traction battery; an electric machine; and one or more controllers programmed to acquire voltage data about the traction battery for a predefined period in response to a disconnection of the traction battery from the electric machine, such that the voltage data for the predefined period, but not immediately after the predefined period, is written to a memory, and initiates processing of the voltage data before the predefined period expires, so that the utilization of a processor performing the processing increases before the predefined period ends. [2] Vehicle according to claim 1, wherein the one or more controllers are further programmed to generate an open-circuit voltage as a result of the processing, which is assigned to the traction battery. [3] Vehicle according to claim 2, wherein the one or more controllers are further programmed to charge or discharge the traction battery according to power limits based on the open-circuit voltage. [4] Vehicle according to claim 1, further comprising gates, wherein opening the gates leads to separation. [5] Vehicle according to claim 1, wherein the predefined period takes place while the vehicle is parked. [6] Vehicle according to claim 5, wherein the predefined period takes place while the vehicle is in a mode with the ignition off. [7] Vehicle according to claim 1, wherein the processing ends after the predefined period ends, so that the utilization decreases after the predefined period ends. [8] Performance system for a vehicle, comprising: one or more controllers programmed to write voltage data associated with a vehicle battery to a memory for a predefined period while the vehicle is parked and in a mode with the ignition off, and to initiate processing of the voltage data before the end of the predefined period, so that the processing ends after the predefined period and The utilization of a processor performing the processing increases before the predefined period ends and decreases after the predefined period ends. [9] Power system according to claim 8, wherein the one or more controllers are further programmed to generate an open-circuit voltage as a result of the processing, which is assigned to the battery. [10] Power system according to claim 9, wherein the one or more controllers are further programmed to charge and discharge the battery according to power limits based on the open-circuit voltage. [11] Power system according to claim 8, wherein the one or more controllers are further programmed to write the voltage data in response to a disconnection of the battery from an electric machine of the vehicle. [12] Power system according to claim 11, wherein opening the gates leads to the separation. [13] Methods for a vehicle, comprising: Opening of contactors that are electrically connected between a traction battery and an electric machine; Writing voltage data via the traction battery to a memory for a predefined period in response to opening; Initiating processing of the voltage data before the end of the predefined period to generate an open-circuit voltage for the traction battery; and Charging or discharging the traction battery according to power limits based on the open-circuit voltage. [14] Method according to claim 13, further comprising completing the processing after the end of the predefined period. [15] Method according to claim 13, wherein the opening takes place while the vehicle is parked.

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