Charging battery to corrected state of charge

Abstract

The present disclosure provides charging a battery to a corrected state of charge. Systems and methods for estimating a state of charge of a traction battery are described. In one example, the state of charge estimate may be corrected via one of three different state of charge estimates. The one of three different state of charge estimates may be selected based on a state of charge correction value or traction battery operating conditions.

Description

Technical Field

[0001] The present description relates to methods and systems for charging a traction battery of an electric vehicle. Background Art

[0002] An electric vehicle may include a traction battery that supplies charge to a propulsion source to propel the electric vehicle. The traction battery has a charge storage capacity that may be displayed or communicated to a human or autonomous driver so that it may be known when the traction battery may need to be recharged. The charge storage capacity may be presented to the driver as a state of charge (SOC) value that may range from 0% to 100%. The SOC may not be measured directly, but it may be inferred. One way to infer the SOC may be to monitor the current flowing into and out of the traction battery, which is known as coulomb counting. However, due to the signal-to-noise ratio at lower current flow rates, the SOC determined from coulomb counting may not be as accurate as desired. Errors in the SOC estimate may not allow the electric vehicle to travel as far as might be expected due to the battery holding less charge than reported, or alternatively, the vehicle owner / operator may be assessed to charge the battery to a requested SOC more than might be expected due to overestimating the amount of charge stored in the battery. Therefore, it may be desirable to provide a way to determine the battery SOC in a manner that is less sensitive to electrical noise at lower current flow rates. Summary of the invention

[0003] The inventors herein have recognized the above problems and have developed a method for charging a traction battery of a vehicle to a requested SOC, the method comprising: retrieving from a memory a predetermined number of SOC correction values ​​accumulated via a first SOC estimation algorithm, a second SOC estimation algorithm, or a third SOC estimation algorithm during charging of the traction battery; charging the traction battery; correcting a current SOC estimation value via a selected SOC estimation algorithm to generate a corrected SOC, the selected SOC estimation algorithm being selected from a plurality of algorithms; and stopping charging of the traction battery based on the corrected SOC.

[0004] By stopping charging of the traction battery in response to a corrected SOC based on a selected SOC estimation algorithm selected from a plurality of algorithms, a more accurate SOC estimate may be generated during vehicle operating conditions where a coulomb counting estimated SOC may be less accurate. The plurality of algorithms may include an algorithm based on battery open circuit voltage (OCV) and an algorithm based on instantaneous battery operating conditions.

[0005] The present description may provide several advantages. Specifically, the method may enhance battery SOC estimation during conditions where coulomb counting may be less accurate. Furthermore, the method may compensate the SOC estimate for vehicle and battery conditions. Additionally, the method may control battery charging so that the traction battery may be charged to a level closer to a requested SOC level.

[0006] The above advantages and other advantages and features of the present specification will be readily apparent from the following detailed description when read alone or in conjunction with the accompanying drawings.

[0007] The above summary is provided to introduce a series of concepts that are further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Advantages described herein will be more fully understood by reading examples of embodiments referred to herein as detailed descriptions when read alone or with reference to the accompanying drawings, in which:

[0009] Figure 1 is a schematic diagram of a vehicle including an electrical energy storage device and an electric motor for propulsion;

[0010] Figure 2 A graph showing the relationship between the open circuit voltage of a battery and the state of charge of the battery;

[0011] Figure 3 is a flow chart of a first method for estimating a battery state of charge;

[0012] Figure 4 is a flow chart of a second method for estimating a battery state of charge;

[0013] Figure 5 is a flow chart of a third method for estimating a battery state of charge;

[0014] Figure 6 is a flow chart for selecting a battery state of charge estimation algorithm to determine a first manner of battery state of charge; and

[0015] Figure 7 is a flow chart of a manner of selecting an SOC estimation algorithm and correcting a battery state of charge estimate based on a plurality of battery state of charge corrections. DETAILED DESCRIPTION

[0016] The present disclosure relates to charging a traction battery of an electric vehicle. Specifically, three different methods are disclosed for estimating the SOC of the traction battery and charging the traction battery according to the estimated SOC. The electric vehicle may be Figure 1 The relationship between the open circuit voltage (OCV) of a battery and the battery SOC is shown in Figure 2 Shown in. Figures 3 to 5 A flow chart of a method for estimating and correcting traction battery SOC is shown. Figure 6 and Figure 7 A flow chart showing a manner of selecting an SOC correction method from among a plurality of SOC correction methods.

[0017] Figure 1 1 is a schematic diagram of a vehicle 121 including a powertrain or vehicle propulsion system 100. The front of the vehicle 121 is indicated at 110, and the rear of the vehicle 121 is indicated at 111. The vehicle propulsion system 100 includes an electric machine 126. The electric machine 126 can consume or generate electricity depending on its operating mode. Figure 1 , mechanical connections between various components are shown as solid lines, while electrical connections between various components are shown as dashed lines.

[0018] The vehicle propulsion system 100 has a rear axle 122. In some examples, the rear axle 122 may include two half shafts, such as a first half shaft 122a and a second half shaft 122b. The vehicle propulsion system 100 also has front wheels 130 and rear wheels 131. The rear wheels 131 may be driven via the motor 126.

[0019] The rear axle 122 is coupled to the motor 126. The rear drive unit 136 can transfer power from the motor 126 to the axle 122, thereby rotating the rear wheels 131. The rear drive unit 136 may include a gearbox 171, which includes a low range 175 and a high range 177 coupled to the motor 126 via an output shaft 126a of the motor 126. The low range 175 can be engaged via a fully closed low range clutch 176. The high range 177 can be engaged via a fully closed high range clutch 178. The high range clutch 178 and the low range clutch 176 can be opened and closed via commands received by the rear drive unit 136 via a controller area network (CAN) 199. Alternatively, the high range clutch 178 and the low range clutch 176 can be opened and closed via a digital output or pulse width provided by the control system 114. The rear drive unit 136 may include a differential 128 so that torque may be provided to the first half-shaft 122 a and the second half-shaft 122 b. In some examples, an electronically controlled differential clutch (not shown) may be included in the rear drive unit 136 .

[0020] The motor 126 may receive power from an onboard electrical energy storage device 132. In addition, the motor 126 may provide a generator function to convert the kinetic energy of the vehicle into electrical energy, which may be stored at the electrical energy storage device 132 for later use by the motor 126. An inverter system controller (ISC) 134 may convert the alternating current generated by the motor 126 into direct current for storage at the electrical energy storage device 132, and vice versa. The electric drive system 135 includes the motor 126 and the inverter system controller 134. The inverter system controller may include a microcontroller, a memory (e.g., a random access memory and a read-only memory), and an input / output circuit (not shown). The electrical energy storage device 132 may be a battery (e.g., a traction battery that provides energy to propel the vehicle), a capacitor, an inductor, or other electrical energy storage device. The power flowing into the electric drive system 135 may be monitored via a current sensor 145 and a voltage sensor 146. The position and speed of the motor 126 may be monitored via a position sensor 147. The torque generated by the electric machine 126 may be monitored via a torque sensor 148 .

[0021] In some examples, electrical energy storage device 132 can be configured to store electrical energy that can be provided to other electrical loads resident on the vehicle (in addition to the motor), including cabin heating and air conditioning systems, engine starting systems, headlight systems, cabin audio and video systems, etc.

[0022] The control system 114 may communicate with the motor 126, the energy storage device 132, the inverter system controller 134, etc. The control system 114 may receive sensory feedback information from the electric drive system 135, the energy storage device 132, etc. In addition, the control system 114 may send control signals to the electric drive system 135, the energy storage device 132, etc. in response to the sensory feedback. The control system 114 may receive an indication of an operator-requested output of the vehicle propulsion system from the human operator 102 or the autonomous controller. For example, the control system 114 may receive sensory feedback from a driver demand pedal position sensor 194 in communication with a driver demand pedal 192. The pedal 192 may schematically refer to a driver demand pedal. Similarly, the control system 114 may receive an indication of vehicle braking requested by the operator via the human operator 102 or the autonomous controller. For example, the control system 114 may receive sensory feedback from a brake pedal position sensor 157 in communication with a brake pedal 156.

[0023] The energy storage device 132 may periodically receive electrical energy from a power source residing outside the vehicle (e.g., not part of the vehicle), such as a fast charging station 1 (not shown) of a fixed power grid. As a non-limiting example, the vehicle propulsion system 100 may be configured as a plug-in electric vehicle (EV), whereby electrical energy may be supplied to the energy storage device 132 via the fast charging station 1 and the power grid (not shown). The fast charging station may be electrically coupled to the vehicle socket 3 via the plug 2. The socket 3 may be electrically coupled to the energy storage device 132.

[0024] The energy storage device 132 includes an energy storage device controller 139 and a power distribution module 138. The energy storage device controller 139 can provide charge balancing between energy storage elements (e.g., battery cells) and communication with other vehicle controllers (e.g., controller 112). In addition, the controller 139 can control the charging of the energy storage device 132. The energy storage device controller 139 includes a core or processor 139a, a memory 139b (e.g., read-only and / or random access), and analog and digital input / output 139c. The power distribution module 138 controls the flow of power into and out of the energy storage device 132.

[0025] One or more wheel speed sensors (WSS) 195 may be coupled to one or more wheels of vehicle propulsion system 100. The wheel speed sensors may detect the rotational speed of each wheel. Such an example of a WSS may include a permanent magnet type sensor.

[0026] The controller 112 may include a portion of the control system 114. In some examples, the controller 112 may be a single controller for the vehicle. The control system 114 is shown as receiving information from a plurality of sensors 116 (various examples of which are described herein) and sending control signals to a plurality of actuators 181 (various examples of which are described herein). As an example, the sensor 116 may include a tire pressure sensor (not shown), a wheel speed sensor 195, etc. In some examples, sensors associated with the motor 126, the wheel speed sensor 195, etc. may transmit information about various states of motor operation to the controller 112. The controller 112 includes a non-transitory (e.g., read-only memory) 165, a random access memory 166, a digital input / output 168, and a microcontroller 167. The controller 112 may receive input data via a CAN 199 and provide the data to a human / machine interface 140. The controller 112 may be an additional controller to the inverter system controller 134, or alternatively, it may be a controller that is part of the inverter system controller 134. The controller 112 may receive vehicle navigation and travel route data (eg, travel distance, travel start location, travel end location, direct current fast charging (DCFC) station locations, road grade, geographic data, etc.) from the navigation system 150 .

[0027] therefore, Figure 1 A system is provided, the system comprising: a traction battery; and a controller, the controller comprising executable instructions, the executable instructions causing the controller to correct a coulomb-based battery state of charge value in response to a battery state of charge estimate based on a battery voltage, a battery current, and a battery temperature. In a first example, the system further comprises additional executable instructions, the additional executable instructions causing the controller to look up a correction value for the traction battery based on the battery state of charge estimate based on the battery voltage, the battery current, and the temperature. In a second example, which may include the first example, the system further comprises additional executable instructions to supply charge to the traction battery within a predetermined amount of time. In a third example, which may include one or both of the first and second examples, the system further comprises additional executable instructions to supply charge to the traction battery via a current less than a threshold amount. In a fourth example, which may include one or more of the first to third examples, the system further comprises additional executable instructions to report when the battery state of charge is equal to a requested battery state of charge. In a fifth example, which may include one or more of the first to fourth examples, the system comprises wherein the requested battery state of charge is received via a human / machine interface. In a sixth example, which may include one or more of the first to fifth examples, the system further includes additional executable instructions to reset the amount of time the traction battery has been charged to zero.

[0028] In another representation, Figure 1A system is provided, the system comprising: a traction battery; and a controller, the controller comprising executable instructions, the executable instructions causing the controller to: receive a requested state of charge (SOC) for the traction battery, retrieve from a memory a predetermined number of SOC correction values ​​accumulated via a first SOC estimation algorithm, a second SOC estimation algorithm, or a third SOC estimation algorithm during charging of the traction battery, charge the traction battery to the requested SOC, and correct a current SOC estimation value via the selected SOC estimation algorithm to achieve the requested SOC. In a first example, the system further comprises additional executable instructions causing the controller to charge the battery to a voltage corresponding to the SOC using a current less than a cutoff current. In a second example, the system further comprises additional executable instructions to correct the SOC based on an amount of time since the traction battery was last connected to electric vehicle supply equipment to charge the traction battery. In a third example, which may include one or both of the first and second examples, the system comprises wherein the first SOC algorithm is based on a battery open circuit voltage. In a fourth example, which may include one or more of the first to third examples, the system includes where the second SOC algorithm is based on an instantaneous SOC estimate. In a fifth example, which may include one or more of the first to fourth examples, the system includes where the instantaneous SOC estimate is based on an instantaneous voltage of the traction battery and an instantaneous current of the traction battery. In a sixth example, which may include one or more of the first to fifth examples, the system includes where the third SOC algorithm is based on a battery open circuit voltage while the traction battery maintains zero input and output current.

[0029] Reference now Figure 2 , a graph 200 showing the relationship between open circuit battery voltage and traction battery state of charge (SOC) is shown. The vertical axis represents the open circuit battery voltage, and the open circuit voltage increases in the direction of the vertical axis arrow. When no electrical load is connected to the battery, the open circuit voltage can be measured via a voltmeter. The horizontal axis represents the traction battery SOC, and the SOC increases from Figure 2 Left to Figure 2 Curve 202 shows the relationship between the battery open circuit voltage and the battery state of charge.

[0030] In one example, curve 202 may be stored in controller memory and referenced by an open circuit voltage of a traction battery. When a requested traction battery SOC is used to reference a curve or function representing curve 202, the reference curve outputs a battery open circuit voltage.

[0031] Reference now Figure 3, showing a first method for charging the traction battery to a requested state of charge. The method 300 may be communicated to a controller (eg, the energy storage device controller 139) via a Figure 1 The method 300 is executed in cooperation with the system to control the charging of the traction battery. At least a portion of the method 300 may be included as executable instructions stored in a non-transitory memory such as Figure 1 in the system shown and in cooperation with the system described. Figure 3 When the method is implemented as executable instructions stored in a controller memory, the method can cause the controller to actuate actuators in the real world and receive data and signals from the sensors described herein.

[0032] At 302, method 300 determines a requested SOC. In one example, a human vehicle operator may request that the SOC value be changed to a value greater than zero and less than or equal to 100%. The human vehicle operator may input the requested SOC into the human / machine interface 140. Alternatively, a cloud server may request that the vehicle be charged to a specific SOC value via a satellite, cellular network, or communication means. The requested SOC may also be referred to as an OCV-based SOC (e.g., SOCocv). The requested SOC may be converted into a requested SOC for each battery cell of the traction battery. Thus, the requested SOC may be for a separate or only battery cell of the traction battery. Method 300 proceeds to 304.

[0033] At 304, method 300 begins charging the traction battery so that the traction battery can be charged to the requested SOC. Charging may be initiated via sending a signal or data to electric vehicle supply equipment (EVSE) (not shown). The EVSE may supply charge to the traction battery at a predetermined rate or at a rate that has been requested via a vehicle controller. Method 300 proceeds to 306.

[0034] At 306, method 300 determines an open circuit voltage corresponding to the requested battery SOC. The target or requested SOC determined at 304 may be used to reference a table or function (e.g., Figure 2 ), and the table or function outputs a target or requested traction battery OCV based on the requested or target battery SOC. After determining the target or requested battery OCV, method 300 proceeds to 308.

[0035] At 308, method 300 determines a target control voltage for the traction battery by adding the offset voltage to the target open circuit voltage of the battery determined at 306. For example, if the target battery open circuit voltage is 3.6 volts, an offset voltage of 40 millivolts may be added to the target open circuit battery voltage of 3.6 volts to generate a target control voltage of 3.64 volts for the battery of the traction battery. The offset voltage may be incrementally increased at a predetermined rate until the target voltage is reached. Method 300 proceeds to 310.

[0036] At 310, method 300 charges the traction battery to the calculated target or requested control voltage determined at 308. The cells of the traction battery may be charged with an amount of current to the target or requested voltage of the battery until the current drops below a threshold current (e.g., a cutoff current). Method 300 may periodically stop charging of an individual traction battery for a short amount of time to measure the OCV of the traction battery. Method 300 proceeds to 312.

[0037] At 312, method 300 determines whether the traction battery OCV is equal to or greater than the target control voltage. If so, the answer is yes and method 300 proceeds to 314. Otherwise, the answer is no and method 300 returns to 304. Method 300 may determine the OCV of the traction battery at predetermined time intervals by isolating the traction battery from the external load and measuring the traction battery voltage.

[0038] At 314 , method 300 stops charging the traction battery because the traction battery open circuit voltage is equal to or greater than the open circuit voltage associated with the requested SOC. Method 300 proceeds to 316 .

[0039] At 316, method 300 generates a correction value between the coulomb counting method for determining SOC and estimating SOC according to the open circuit voltage (OCV) method for estimating SOC. The correction is stored in the controller random access memory along with other corrections determined in the same manner during other traction battery charging phases. In one example, the correction can be determined by the following equation:

[0040] S0Ccor1=(S0Ccoul-SOCocv)·G

[0041] Where SOCcor1 is the SOC correction value based on the counted coulombs and open circuit voltage, and SOCcoul is the SOC estimated based on the coulomb counts (e.g., Where t is time, t0 is the initial time, I is the current, and Q n is the charge capacity of the battery), SOCocv is the SOC based on the OCV of the individual battery cells of the traction battery, and G1 is a predetermined gain value (eg, a real number). Method 300 proceeds to exit.

[0042] Reference now Figure 4 , showing a second method for charging the traction battery to a requested state of charge. The method 400 may be communicated to a controller (eg, the energy storage device controller 139) via a Figure 1 The method 400 may be executed in cooperation with a system to control the charging of the traction battery. At least a portion of the method 400 may be included as executable instructions stored in a non-transitory memory. Figure 1 in and in cooperation with the system shown. Figure 4 When the method is implemented as executable instructions stored in a controller memory, the method can cause the controller to actuate actuators in the real world and receive data and signals from the sensors described herein.

[0043] At 402, method 400 determines a requested SOC. In one example, a human vehicle operator may request that the SOC value be changed to a value greater than zero and less than or equal to 100%. The human vehicle operator may input the requested SOC into human / machine interface 140. Alternatively, a cloud server may request that the vehicle be charged to a specific SOC value via satellite, cellular network, or communication means. Method 400 proceeds to 404.

[0044] At 404, method 400 performs target SOC charging. Target SOC charging includes adjusting the SOC charge level of the traction battery to a level requested according to a target or requested SOC for the entire traction battery by a vehicle occupant or a cloud server. In other words, the SOC value input by the vehicle occupant or the cloud server is converted to a requested or target SOC value for the battery of the traction battery, and charge is supplied to the battery and the battery so that the target SOC level of the battery can be reached. A correction value may be added to the requested or target SOC value to determine a corrected SOC, and charge may be supplied so that the SOC of the battery reaches the corrected SOC value. The initial correction value may be zero. Method 400 proceeds to 406.

[0045] At 406, method 400 determines whether the target or requested SOC of the battery has been reached. In one example, method 400 determines whether the target SOC of the battery has been reached by determining whether the coulomb counting-based SOC of the battery plus the SOC correction of the battery is greater than or equal to (e.g., >=) the target or requested SOC of the battery. If so, the answer is yes, and method 400 proceeds to 420. Otherwise, the answer is no, and method 400 proceeds to 408.

[0046] At 420 , method 400 reports, via a message on a human / machine interface, that the target or requested SOC for the individual battery cell has been reached. Method 400 stops charging the battery and exits.

[0047] At 408, method 400 determines whether the amount of time to charge the traction battery since the vehicle was last electrically coupled to the EVSE and began receiving a charge, or alternatively, the time since the charge timer was last reset, is greater than a first threshold amount of time (e.g., X minutes, where "X" is a variable). If so, the answer is yes, and method 400 proceeds to 410. Otherwise, the answer is no, and method 400 returns to 404. Method 400 makes an assessment of the charging time so that a meaningful correction voltage can be determined, and so that the correction can be less sensitive to signal noise (if present).

[0048] At 410, method 400 determines whether the Y-second root mean square (RMS) current (e.g., the RMS current measured over Y seconds) entering or leaving the traction battery is less than Z amperes, where Y is a predetermined time interval and Z is a predetermined amount of current. If method 400 determines that the Y-second RMS current is less than Z, the answer is yes and method 400 proceeds to 430. Otherwise, the answer is no and method 400 proceeds to 412. In this manner, method 400 can determine whether the current flowing through the battery is low enough so that an accurate instantaneous SOC estimate can be determined even if the battery voltage being measured is not the open circuit voltage.

[0049] At 412 , method 400 controls the Y-second RMS current flowing to the battery to be less than Z amperes. In one example, method 400 may command the EVSE to adjust the current supplied to the traction battery so that the current flowing through the battery may be less than Z amperes. Method 400 returns to 410 .

[0050] At 430, method 400 performs an instantaneous SOC correction based on voltage, current, and battery temperature (VIT). In one example, method 400 may reference a table that stores empirically determined SOC estimates. The table may be referenced via an instantaneous battery voltage (e.g., the battery voltage when current is flowing from or to the battery), an instantaneous battery current, and a battery temperature. In one example, the SOC correction may be determined via the following equation:

[0051] SOCcor2=(S0Ccoul-SOCinst)·G2

[0052] where SOCcor2 is the correction value based on the coulomb count and instantaneous SOC, and SOCcoul is the estimated SOC based on the coulomb count (e.g., Where t is time, t0 is the initial time, I is the current, and Q nis the charge capacity of the battery), SOCinst is the SOC determined based on the instantaneous battery voltage, instantaneous battery current, and instantaneous battery temperature as a function of an instantaneous SOC value determined empirically with reference to an instantaneous battery voltage, an instantaneous battery current, and an instantaneous battery temperature. G2 is a predetermined gain value (e.g., a real number). When a load is connected to the battery and current is flowing through the battery, the instantaneous battery voltage can be determined from the battery. Therefore, the instantaneous voltage is not an open circuit voltage. In other examples, method 400 can determine an offset correction value (e.g., 20 millivolts) that is added to SOCcoul(t) to generate a corrected SOC. Method 300 proceeds to 432.

[0053] The correction is stored in the controller random access memory along with other corrections determined in the same manner during other traction battery charging phases. Method 400 proceeds to 432 .

[0054] At 432 , method 400 resets a charge timer (e.g., a timer that tracks the amount of time since the last reset of the charge timer or the amount of time since the vehicle was last connected to the EVSE and began receiving charge) to reset the amount of time the battery has received charge to zero. Method 400 returns to 404 .

[0055] Reference now Figure 5 , showing a third method for charging the traction battery to a requested state of charge. The method 500 may be communicated to a controller (eg, the energy storage device controller 139) via a Figure 1 The method 500 may be executed in cooperation with a system to control the charging of the traction battery. At least a portion of the method 500 may be included as executable instructions stored in a non-transitory memory such as Figure 1 in and in cooperation with the system shown. Figure 5 When the method is implemented as executable instructions stored in a controller memory, the method can cause the controller to actuate actuators in the real world and receive data and signals from the sensors described herein.

[0056] At 502, method 500 determines a requested SOC. In one example, a human vehicle operator may request that the SOC value be changed to a value greater than zero and less than or equal to 100%. The human vehicle operator may input the requested SOC into human / machine interface 140. Alternatively, a cloud server may request that the vehicle be charged to a specific SOC value via satellite, cellular network, or communication means. The requested SOC may be converted to a requested SOC for each battery cell of the traction battery. Thus, the requested SOC may be for an individual or only battery cell of the traction battery. Method 500 proceeds to 504.

[0057] At 504, method 500 performs target SOC charging. Target SOC charging includes adjusting the SOC charge level of the traction battery to a level requested according to a target or requested SOC for the entire traction battery by a vehicle occupant or a cloud server. In other words, the SOC level input by the vehicle occupant or the cloud server is converted to a requested or target SOC level of the battery of the traction battery, and charge is supplied to the battery and the battery so that the target SOC level of the battery can be reached. A correction value may be added to the requested or target SOC value to determine a corrected SOC, and charge may be supplied so that the SOC of the battery reaches the corrected SOC value. The initial correction value may be zero. Method 500 proceeds to 506.

[0058] At 506, method 500 determines whether the target SOC has been reached. In one example, method 500 determines whether the target SOC of the battery has been reached by determining whether the coulomb counting-based SOC of the battery plus the SOC correction of the battery is greater than or equal to (e.g., >=) the target or requested SOC of the battery. If so, the answer is yes and method 500 proceeds to 520. Otherwise, the answer is no and method 500 proceeds to 508.

[0059] At 520 , method 500 reports, via a message on the human / machine interface, that the target or requested SOC for the battery has been reached. Method 500 stops charging the battery and exits.

[0060] At 508, method 500 determines whether the amount of time that the traction battery has been charged since the vehicle was last electrically coupled to the EVSE and began receiving a charge, or alternatively, the time since the charge timer was last reset, is greater than a first threshold amount of time (e.g., X minutes, where "X" is a variable). If so, the answer is yes and method 500 proceeds to 510. Otherwise, the answer is no and method 500 returns to 504. Method 500 makes an assessment of the charging time so that a meaningful correction voltage can be determined and so that the correction can be less sensitive to signal noise (if present).

[0061] At 510 , method 500 maintains zero current flow into and out of the traction battery for a predetermined amount of time (e.g., Y seconds). By temporarily pausing charging of the traction battery, a better estimate of the SOC may be obtained so that the traction battery may be charged closer to the requested SOC. Method 500 proceeds to 512 .

[0062] At 512 , method 500 performs a SOC-OCV adjustment or correction. In one example, the correction may be determined by the following equation:

[0063] SOCcor3=(SOCcoul-SOCocV)·G3

[0064] Where SOCcor3 is the correction value based on the counted coulombs and open circuit voltage, and SOCcoul is the estimated SOC based on the coulomb counts (e.g., Where t is time, t0 is the initial time, I is the current, and Q n is the charge capacity of the battery), SOCocv is the SOC based on OCV, and G3 is a predetermined gain value (e.g., a real number). The correction is stored in the controller random access memory along with other corrections determined in the same manner during other traction battery charging phases. In other examples, method 500 may determine an offset correction value (e.g., 20 millivolts) that is added to SOCcoul(t) to generate a corrected SOC. Method 500 proceeds to 522.

[0065] At 522 , method 500 resets a charge timer (e.g., a timer that tracks the amount of time since the last reset of the charge timer or the amount of time since the vehicle was last connected to the EVSE and began receiving charge) to reset the amount of time the battery has received charge to zero. Method 500 returns to 504 .

[0066] Thus, method 500 charges the traction battery for a predetermined amount of time, maintains the current flowing into and out of the traction battery at zero after the predetermined amount of time, and estimates the SOC based on the battery OCV after maintaining the traction battery current at zero amps. This may allow the SOC to be accurately determined during charging, regardless of whether the current flowing into the battery during the charging process is greater or less. Thus, an accurate SOC estimate may be provided regardless of whether the traction battery is charged via a supercharger or a home charging station. Turning now to Figure 6 , shows a method for selecting a traction battery charging program from a plurality of traction battery charging programs. The method 600 may be communicated via a controller (eg, the energy storage device controller 139) with Figure 1 The method 600 may be executed in cooperation with a system to control the charging of the traction battery. At least a portion of the method 600 may be included as executable instructions stored in a non-transitory memory such as Figure 1 in and in cooperation with the system shown. Figure 6 When the method is implemented as executable instructions stored in a controller memory, the method can cause the controller to actuate actuators in the real world and receive data and signals from the sensors described herein.

[0067] At 602, method 600 determines whether the EVSE and the vehicle owner / user allow a longer period of time during which the charge can be cut off during the time when the vehicle is electrically connected to the EVSE. In one example, the longer period of time can be a period of time that can range from 2 minutes to 10 minutes. The user can enter the amount of time that the charge in and out of the battery can be cut off so that a more reliable relationship between OCV and SOC can be achieved to estimate the SOC. In addition, based on the EVSE utilization in the vicinity of the vehicle, the ambient air temperature, and other parameters, some EVSEs may or may not adapt to the period of time during which the current supplied to the battery is cut off. If method 600 determines that the current can be cut off from the traction battery for a longer period of time when the vehicle is electrically connected to the EVSE, the answer is yes and method 600 proceeds to 604. Otherwise, the answer is no, and method 600 proceeds to 610.

[0068] At 604, method 600 determines whether the SOC estimate is greater than or expected to be greater than a second threshold SOC. In one example, method 600 may determine that the SOC is greater than or expected to be greater than the second threshold SOC based on the initial battery SOC immediately prior to charging, the charge rate to be delivered to the traction battery, and the expected amount of time to charge the traction battery. If method 600 determines that the SOC estimate during charging will or is expected to exceed the second threshold charge amount, the answer is yes and method 600 proceeds to 620. Otherwise, the answer is no and method 600 proceeds to 606.

[0069] At 620 , method 600 selects Figure 5 method and based on Figure 5 When the charge to the traction battery is allowed to be cut off while the vehicle is electrically coupled to the EVSE and when the SOC estimate is greater than or expected to be greater than a second threshold SOC amount, Figure 5 The method may provide a more accurate SOC estimation value. Method 600 proceeds to exit.

[0070] At 606, method 600 selects Figure 4 method and based on Figure 4 When the charge to the traction battery is allowed to be cut off while the vehicle is electrically coupled to the EVSE and when the SOC estimate is less than or expected to be less than a second threshold SOC amount, Figure 4 The method may provide a more accurate SOC estimation value. Method 600 proceeds to exit.

[0071] At 610, method 600 determines whether the SOC estimate is greater than or expected to be greater than a first threshold SOC. In one example, method 600 may determine that the SOC is greater than or expected to be greater than the first threshold SOC based on the initial battery SOC immediately prior to charging, the charge rate to be delivered to the traction battery, and the expected amount of time to charge the traction battery. If method 600 determines that the SOC estimate during charging will or is expected to exceed the first threshold charge amount, the answer is yes and method 600 proceeds to 612. Otherwise, the answer is no and method 600 proceeds to 614.

[0072] At 612, method 600 selects Figure 5 method and based on Figure 5 When the charge to the traction battery is allowed to be cut off while the vehicle is electrically coupled to the EVSE and when the SOC estimate is greater than or expected to be greater than a first threshold SOC amount, Figure 5 The method may provide a more accurate SOC estimation value. Method 600 proceeds to exit.

[0073] At 614 , method 600 selects Figure 3 method and based on Figure 3 When the charge to the traction battery is not allowed to be cut off while the vehicle is electrically coupled to the EVSE and when the SOC estimate is less than or expected to be less than a first threshold SOC amount, Figure 3 The method may provide a more accurate SOC estimation value. Method 600 proceeds to exit.

[0074] In this way, method 600 may select a method for charging the traction battery, and the selected charging method may provide a higher accuracy for the SOC estimation value.The method selects a SOC estimation process taking into account different SOC estimation properties and SOC levels.

[0075] Reference now Figure 7 , shows a method for charging individual cells of a traction battery and selecting a traction battery charging program from a plurality of traction battery charging programs. The method 700 may be communicated to a controller (e.g., an energy storage device controller 139) via Figure 1 The method 700 is executed in cooperation with the system to control the charging of the traction battery. At least a portion of the method 700 may be included as executable instructions stored in a non-transitory memory such as Figure 1 in the system shown and in cooperation with the system described. Figure 7 When the method is implemented as executable instructions stored in a controller memory, the method can cause the controller to actuate actuators in the real world and receive data and signals from the sensors described herein.

[0076] At 702, method 700 determines a requested SOC. In one example, a human vehicle operator may request that the SOC value be changed to a value greater than zero and less than or equal to 100%. The human vehicle operator may input the requested SOC into human / machine interface 140. Alternatively, a cloud server may request that the vehicle be charged to a specific SOC value via satellite, cellular network, or communication means. The requested SOC may be converted to a requested SOC for each battery cell of the traction battery. Thus, the requested SOC may be for an individual or only battery cell of the traction battery. Method 700 proceeds to 704.

[0077] At 704, method 700 retrieves SOC correction values ​​from a previous traction battery charging routine from a controller memory (e.g., random access memory). Method 700 may retrieve a predetermined actual total number of SOC correction values ​​to achieve consistency. SOC correction values ​​may be accumulated during charging of the traction battery while estimating the SOC of the traction battery via the first method, the second method, or the third method. After retrieving the SOC correction values, method 700 proceeds to 706.

[0078] At 706, method 700 begins charging the traction battery. After the vehicle communicates to the EVSE that charging can begin, the traction battery can begin charging. After information is exchanged between the vehicle and the EVSE that the traction battery is about to be charged, the vehicle can communicate to the EVSE that charging can begin. Method 700 proceeds to 708.

[0079] At 708, method 700 adaptively selects a SOC estimation algorithm based on a minimum SOC charge correction value from a previous traction battery charging event and a time taken to charge the traction battery during a current period that the vehicle is electrically coupled to the EVSE. Additionally, method 700 may consider a rate at which charge flows from the EVSE to the traction battery to adaptively select a SOC estimation algorithm.

[0080] In one example, the method 700 may group the battery charging rates into three or more groups (e.g., low charging rate, medium charging rate, and high charging rate). The method 700 may also group the battery charging time into three or more groups (e.g., low charging time, medium charging time, long charging time), and may assign a value to each battery charging method based on the current traction battery charging rate and charging time. For example, for a lower charging rate, a value may be assigned to Figure 4 The method assigns lower values, and can be Figure 3 and Figure 5 For example, for a higher charging rate, Figure 3 and Figure 5 The method assigns lower values ​​and can be Figure 4Similarly, for a shorter period of time when the traction battery has been charged, Figure 4 The method assigns smaller values ​​and can be Figure 3 and Figure 5 For a longer period of time when the traction battery has been charged, Figure 4 The method assigns larger values ​​and can be Figure 3 and Figure 5 method to assign smaller values.

[0081] against Figure 3 The SOC correction value of the method can be added for Figure 3 The method of charging rate and charging time to generate the value of Figure 3 Similarly, for Figure 4 The SOC correction value of the method can be added for Figure 4 The method of charging rate and charging time to generate the value of Figure 4 Similarly, for Figure 5 The SOC correction value of the method can be added for Figure 5 The method of charging rate and charging time to generate the value of Figure 5 Then, method 700 can select Figure 3 methods, Figure 4 Methods and Figure 5 The method 700 proceeds to 710 .

[0082] At 710, method 700 corrects the current SOC, which may be estimated based on coulomb counting, according to the selected SOC algorithm. In one example, the correction may be determined by the following equation:

[0083] SOCcorr(t)=(SOCcoul(t)-SOCsel)·G2

[0084] Where SOCcorr(t) is the SOC correction at the current time t, and SOCcoul is based on The SOC based on coulomb counting, t0 is the initial time, I is the current, and Q n is the charge capacity of the battery, SOCsel is the SOC estimation value of the individual battery cell generated by applying the selected SOC determination method, and G2 is a predetermined gain value (eg, a real number).

[0085] The current SOC is adjusted according to the correction value via the following equation to generate a corrected SOC:

[0086] corSOC(t)=SOCcoul(t)+SOCcorr(t)

[0087] Where corSOC is the corrected SOC. Method 700 proceeds to 712 .

[0088] At 712 , the method 700 stores the correction accumulation in step 710 to a memory (eg, random access memory). The method 700 proceeds to 714 .

[0089] At 714 , method 700 determines whether the traction battery is charged to the corrected SOC. If so, the answer is yes and method 700 proceeds to 716 . Otherwise, the answer is no and method 700 returns to 710 .

[0090] Method 700 stops charging the traction battery at 716. After stopping traction battery charging, method 700 proceeds to exit.

[0091] In this way, method 700 may select a method to correct the SOC according to correction values ​​of multiple SOC correction methods. The SOC correction method may be selected based on the charge rate of the traction battery, the amount of time the traction battery has been charged recently, and the accumulated SOC correction values.

[0092] Figure 6 and Figure 7A method for charging a traction battery of a vehicle to a requested state of charge (SOC) may be provided, comprising: retrieving from a memory a predetermined number of SOC correction values ​​accumulated via a first SOC estimation algorithm, a second SOC estimation algorithm, or a third SOC estimation algorithm during charging of the traction battery; charging the traction battery; correcting a current SOC estimation value via a selected SOC estimation algorithm to generate a corrected SOC, the selected SOC estimation algorithm being selected from a plurality of algorithms; and stopping charging of the traction battery based on the corrected SOC. In a first example, the method further comprises storing the current SOC correction value accumulated via applying the selected SOC estimation algorithm in a memory. In a second example, which may include the first example, the method comprises wherein the first SOC algorithm is based on a battery open circuit voltage, a target control voltage, and a minimum cutoff current. In a third example, which may include one or both of the first and second examples, the method comprises wherein the second SOC algorithm is based on an instantaneous SOC estimation value. In a fourth example, which may include one or more of the first to third examples, the method comprises wherein the instantaneous SOC estimation value is based on an instantaneous voltage of the traction battery and an instantaneous current of the traction battery. In a fifth example, which may include one or more of the first to fourth examples, the method includes where the third SOC algorithm is based on a battery open circuit voltage while the traction battery maintains zero input and output current. In a sixth example, which may include one or more of the first to fifth examples, the method includes where the requested SOC is less than 100%. In a seventh example, which may include one or more of the first to sixth examples, the method also includes adaptively selecting a SOC estimation algorithm based on a minimum accumulated SOC correction and an amount of time since the vehicle was last coupled to electric vehicle supply equipment to charge the traction battery.

[0093] Figure 6 and Figure 7A method for charging a traction battery is also provided, comprising: estimating a state of charge of a traction battery via coulomb counting; and correcting the state of charge via an open circuit voltage based state of charge estimate for the traction battery. In a first example, the method includes wherein the correction of the state of charge via the open circuit voltage is performed in response to the state of charge being greater than a threshold state of charge. In a second example that may include the first example, the method further includes correcting the state of charge via an instantaneous state of charge estimate in response to the state of charge being less than a threshold state of charge. In a third example that may include one or both of the first and second examples, the method includes wherein the instantaneous state of charge is based on an instantaneous voltage of the traction battery, an instantaneous current of the traction battery, and an instantaneous temperature of the traction battery. In a fourth example that may include one or more of the first to third examples, the method includes wherein the correction of the state of charge via the instantaneous state of charge is performed after charging the traction battery for a predetermined amount of time.

[0094] It should be noted that the example control and estimation procedures included herein can be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be implemented by a control system including a controller in combination with various sensors, actuators and other engine hardware. The specific procedures described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Thus, the various actions, operations and / or functions shown may be executed in the order shown, executed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown may be repeatedly performed according to the specific strategy used. In addition, at least a portion of the described actions, operations and / or functions may be graphically represented as codes in a non-transitory memory of a computer-readable storage medium to be programmed into the control system. When the described actions are performed by executing instructions in conjunction with one or more controllers in a system including various engine hardware components, the control actions may also transform the operating state of one or more sensors or actuators in the physical world.

[0095] This specification ends here. Without departing from the spirit and scope of this specification, those skilled in the art will think of many variations and modifications after reading this specification.

[0096] According to the present invention, a method for charging a traction battery of a vehicle to a requested state of charge (SOC) includes: retrieving from a memory a predetermined number of SOC correction values ​​accumulated via a first SOC estimation algorithm, a second SOC estimation algorithm, or a third SOC estimation algorithm during charging of the traction battery; charging the traction battery; correcting a current SOC estimation value via a selected SOC estimation algorithm to generate a corrected SOC, the selected SOC estimation algorithm being selected from a plurality of algorithms; and stopping charging of the traction battery based on the corrected SOC.

[0097] In one aspect of the invention, the method includes storing in a memory a current SOC correction value accumulated via application of said selected SOC estimation algorithm.

[0098] In one aspect of the present invention, the first SOC estimation algorithm is based on a battery open circuit voltage, a target control voltage and a minimum cut-off current.

[0099] In one aspect of the present invention, the second SOC estimation algorithm is based on an instantaneous SOC estimation value.

[0100] In one aspect of the invention, the instantaneous SOC estimate is based on an instantaneous voltage of the traction battery and an instantaneous current of the traction battery.

[0101] In one aspect of the present invention, the third SOC estimation algorithm is based on a battery open circuit voltage while the traction battery maintains zero input and output current.

[0102] In one aspect of the invention, the requested SOC is less than 100%.

[0103] In one aspect of the invention, the method includes adaptively selecting the selected SOC estimation algorithm based on a minimum accumulated SOC correction and an amount of time since the vehicle was last coupled to electric vehicle supply equipment to charge the traction battery.

[0104] According to the present invention, a system is provided having: a traction battery; and a controller including executable instructions that cause the controller to correct a coulomb-based battery state of charge value in response to a battery state of charge estimate based on battery voltage, battery current, and battery temperature.

[0105] According to an embodiment, the invention also features additional executable instructions that cause the controller to look up a correction value for the traction battery based on a battery state of charge estimate based on the battery voltage, the battery current, and the temperature.

[0106] According to an embodiment, the invention also features additional executable instructions to supply charge to the traction battery for a predetermined amount of time.

[0107] According to an embodiment, the invention also features additional executable instructions to supply charge to the traction battery via a current that is less than a threshold amount.

[0108] According to an embodiment, the invention also features additional executable instructions to report when the battery state of charge is equal to a requested battery state of charge.

[0109] According to an embodiment, the requested battery state of charge is received via a human / machine interface.

[0110] According to an embodiment, the invention also features additional executable instructions to reset the amount of time the traction battery has been charged to zero.

[0111] According to the present invention, a method for charging a traction battery includes estimating a state of charge of the traction battery via coulomb counting and correcting the state of charge via an open circuit voltage based state of charge estimate for the traction battery.

[0112] In one aspect of the invention, correction of the state of charge via the open circuit voltage is performed in response to the state of charge being greater than a threshold state of charge.

[0113] In one aspect of the invention, the state of charge is corrected via an instantaneous state of charge estimate in response to the state of charge being less than a threshold state of charge.

[0114] In one aspect of the invention, the instantaneous state of charge is based on an instantaneous voltage of the traction battery, an instantaneous current of the traction battery and an instantaneous temperature of the traction battery.

[0115] In one aspect of the invention, the correction of the state of charge via the instantaneous state of charge is performed after charging the traction battery for a predetermined amount of time.

Claims

1. A method for charging a traction battery of a vehicle to a requested state of charge (SOC), comprising: retrieving from a memory a predetermined number of SOC correction values ​​accumulated via a first SOC estimation algorithm, a second SOC estimation algorithm, or a third SOC estimation algorithm during charging of the traction battery; charging the traction battery; correcting a current SOC estimation value via a selected SOC estimation algorithm to generate a corrected SOC, the selected SOC estimation algorithm being selected from a plurality of algorithms; as well as Charging of the traction battery is stopped based on the corrected SOC. 2 . The method of claim 1 , further comprising storing in a memory a current SOC correction value accumulated via application of the selected SOC estimation algorithm. 3 . The method of claim 1 , wherein the first SOC estimation algorithm is based on a battery open circuit voltage, a target control voltage, and a minimum cut-off current. The method of claim 1 , wherein the second SOC estimation algorithm is based on an instantaneous SOC estimation value. 5 . The method of claim 4 , wherein the instantaneous SOC estimate is based on an instantaneous voltage of the traction battery and an instantaneous current of the traction battery.

6. The method of claim 1 wherein the third SOC estimation algorithm is based on a battery open circuit voltage while the traction battery maintains zero input and output current. The method of claim 1 , wherein the requested SOC is less than 100%.

8. The method of claim 1 further comprising adaptively selecting the selected SOC estimation algorithm based on a minimum accumulated SOC correction and an amount of time since the vehicle was last coupled to electric vehicle supply equipment to charge the traction battery.

9. A system comprising: Traction batteries; and A controller includes executable instructions that cause the controller to correct a coulomb-based battery state of charge in response to a battery state of charge estimate based on a battery voltage, a battery current, and a battery temperature.

10. The system of claim 9 further comprising additional executable instructions that cause the controller to look up a correction value for the traction battery based on a battery state of charge estimate based on the battery voltage, the battery current, and the temperature.

11. The system of claim 9, further comprising additional executable instructions to supply charge to the traction battery for a predetermined amount of time.

12. The system of claim 11 further comprising additional executable instructions to supply charge to the traction battery via a current less than a threshold amount.

13. The system of claim 12, further comprising additional executable instructions to report when the battery state of charge is equal to a requested battery state of charge.

14. The system of claim 13, wherein the requested battery state of charge is received via a human / machine interface.

15. The system of claim 14, further comprising additional executable instructions to reset the amount of time the traction battery has been charged to zero.

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