Switching duration setting for battery string state of charge balancing

Abstract

A battery system comprises: two battery modules, each comprising three battery cell strings, the battery cell strings being configured to, at different times: be connected in series and to a first positive terminal via a first switch in the switches; be connected in parallel and to a second positive terminal via a second switch in the switches; and be disconnected from both the first positive terminal and the second positive terminal; and a switch control module configured to: determine the state of charge (SOC) of the strings respectively; determine the period of the stages respectively based on the SOC; determine a first period for connecting a plurality of strings in parallel in the strings; divide one of the stages into N periods of equal length; selectively reduce N; and when the number of first periods ending closest to one of the N period end points is at least a predetermined value, adjust the first period to the corresponding closest period end point of the N period end points.

Description

Technical Field

[0001] The present disclosure relates to vehicles, and more particularly to battery systems for vehicles. Background Art

[0002] The information provided in this section is for the purpose of generally presenting the context of the present disclosure. To the extent described in this section, the work of the presently named inventors and aspects of the description that may not otherwise be prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art with respect to the present disclosure.

[0003] Some types of vehicles include only an internal combustion engine to generate propulsion torque. Hybrid vehicles include both an internal combustion engine and one or more electric motors. Some types of hybrid vehicles utilize both the electric motor and the internal combustion engine in an attempt to achieve greater fuel efficiency than would be possible using only the internal combustion engine. Some types of hybrid vehicles utilize both the electric motor and the internal combustion engine to achieve a greater torque output than the internal combustion engine alone could achieve.

[0004] Some example types of hybrid vehicles include parallel hybrids, series hybrids, and other types of hybrid vehicles. In a parallel hybrid, an electric motor operates in parallel with the engine to combine the power and range advantages of the engine with the efficiency and regenerative braking advantages of the electric motor. In a series hybrid, the engine drives a generator to generate electricity for the electric motor, and the electric motor drives the transmission. This allows the electric motor to assume some of the engine's power responsibilities, which can allow for the use of a smaller and potentially more efficient engine. This application is applicable to electric vehicles, hybrid vehicles, and other types of vehicles. Summary of the Invention

[0005] In a feature, a battery system includes: a first positive terminal; a second positive terminal; a negative terminal; a switch; two battery modules, wherein each of the two battery modules includes three battery cell strings, and the battery cell strings are configured to, at different times: be connected in series via a first switch of the switches and connected to the first positive terminal; be connected in parallel via a second switch of the switches and connected to the second positive terminal; and be disconnected from both the first positive terminal and the second positive terminal; and a switch control module, the switch control module being configured to: determine a state of charge (SOC) of each battery cell string; determine a period of a stage based on the SOC; determine to connect one of the strings to the battery cell string during one of the stages; The method further comprises: dividing the one of the phases into N periods of equal length each having N period end points, one of the N period end points being at the end of the one of the phases; selectively decreasing N; adjusting the first period to a respective period end point closest to the end of the one of the N period end points when the number of first periods closest to the end of the one of the N period end points is at least a predetermined value; and selectively actuating a switch based on the period of the phase and the period of the battery cell string.

[0006] In further features, the predetermined value is 2.

[0007] In further features, the switch control module is configured to selectively decrease N based on a number of first time periods closest to the one of the N time period end points.

[0008] In further features, the switch control module is configured to decrement N when the number of first time periods closest to the one of the N time period end points is less than a predetermined value.

[0009] In further features, the switch control module is configured to decrement N by one.

[0010] In further features, the switch control module is configured to combine the two first time periods in which one of the strings is connected in parallel during the one of the phases, when the two first time periods in which one of the strings is connected in parallel are separated by a time period in which the one of the strings is not connected in parallel, such that the two first time periods are adjacent.

[0011] In further features, the switch control module is configured to set a first period of time of the first one of the strings of one of the battery modules to be longer than a second period of time of the second one of the strings of the one of the battery modules during charging when a first SOC of the first one of the strings of the one of the battery modules is less than a second SOC of the second one of the strings of the one of the battery modules.

[0012] In further features, the switch control module is configured to set a first time period of the first one of the strings of one of the battery modules to be longer than a second time period of the second one of the strings of the one of the battery modules during discharge when a first SOC of the first one of the strings of the one of the battery modules is greater than a second SOC of the second one of the strings of the one of the battery modules.

[0013] In further features, the switch control module is configured to selectively set a first period of a first one of the phases to be longer than a second period of a second one of the phases during charging based on the SOC of the string.

[0014] In further features, the switch control module is configured to selectively set a first period of a first one of the phases to be longer than a second period of a second one of the phases during discharge based on the SOC of the string.

[0015] In further features, the switch control module is configured to determine the period of the phase and the first period of the string based on minimizing an error between SOCs of the strings of battery cells.

[0016] In further features, the error is a sum of squared differences between the SOCs of the strings.

[0017] In further features, each of the strings includes a plurality of battery cells connected in series.

[0018] In further features, the plurality of battery cells includes four 3 volt battery cells.

[0019] In further features, the switch control module is configured to control the switch so that one of the strings is not simultaneously connected to both the first positive terminal and the second positive terminal.

[0020] In further features: the first positive terminal is configured to output a first reference potential; the second positive terminal is configured to output a second reference potential; and the first reference potential is greater than the second reference potential.

[0021] In a feature, a method for a battery comprises: separately determining a state of charge (SOC) of a battery cell string of a battery, the battery comprising: a first positive terminal; a second positive terminal; a negative terminal; a switch; two battery modules, wherein each of the two battery modules comprises three battery cell strings, the battery cell strings being configured to be: connected in series and connected to the first positive terminal via a first switch of the switches; connected in parallel and connected to the second positive terminal via a second switch of the switches; and disconnected from both the first positive terminal and the second positive terminal at different times; separately determining a period of a phase based on the SOC; determining a first period for connecting a plurality of the strings in parallel during one of the phases; dividing the one of the phases into N periods of equal length, each having N period end points, one of the N period end points being at the end of the one of the phases; selectively reducing N; adjusting the first period to the corresponding closest period end point of the N period end points when the number of first periods closest to the end of the one of the N period end points is at least a predetermined value; and selectively actuating the switch based on the period of the phase and the period of the battery cell string.

[0022] In further features, the predetermined value is 2.

[0023] In further features, selectively decreasing N comprises selectively decreasing N based on a number of first time periods closest to the one of the N time period end points.

[0024] In further features, selectively decreasing N includes decrementing N when the number of first time periods closest to the one of the N time period end points is less than a predetermined value.

[0025] Solution 1. A battery system comprising:

[0026] a first positive terminal;

[0027] Second positive terminal;

[0028] negative terminal;

[0029] switch;

[0030] Two battery modules, wherein each of the two battery modules includes three battery cell strings, the battery cell strings being configured to, at different times:

[0031] connected in series via a first one of the switches and connected to the first positive terminal;

[0032] connected in parallel via a second one of the switches and connected to the second positive terminal; and

[0033] disconnecting from both the first positive terminal and the second positive terminal; and

[0034] A switch control module, wherein the switch control module is configured to:

[0035] Determining the state of charge (SOC) of each battery cell string;

[0036] Determine the time period of each stage based on SOC;

[0037] determining a first time period for connecting a plurality of the strings in parallel during one of the phases;

[0038] dividing the one of the phases into N periods of equal length each having N period end points, one of the N period end points being at the end of the one of the phases;

[0039] Selective reduction of N;

[0040] When the number of first time periods closest to the end of one of the N time period end points is at least a predetermined value, adjusting the first time period to the corresponding closest time period end point of the N time period end points; and

[0041] The switches are selectively actuated based on the duration of the phase and the duration of the battery cell string.

[0042] Solution 2. The battery system according to solution 1, wherein the predetermined value is 2.

[0043] Embodiment 3. The battery system of embodiment 1, wherein the switch control module is configured to selectively decrease N based on the number of first time periods closest to the one of the N time period end points.

[0044] Solution 4. The battery system according to solution 1, wherein the switch control module is configured to decrement N when the number of the first time period closest to the one of the N time period end points is less than a predetermined value.

[0045] Option 5. The battery system according to Option 4, wherein the switch control module is configured to decrement N by 1.

[0046] Option 6. The battery system according to Option 1, wherein the switch control module is configured to: when two first time periods in which one of the strings is connected in parallel during the one period in the stage are separated by a time period in which the one of the strings is not connected in parallel, combine the two first time periods in which the one of the strings is connected in parallel during the one period in the stage so that the two first time periods are adjacent.

[0047] Option 7. The battery system according to Option 1, wherein the switch control module is configured to: when a first SOC of a first one of the strings of one of the battery modules is less than a second SOC of a second one of the strings of the one of the battery modules, set a first period of time of the first one of the strings of the one of the battery modules to be longer than a second period of time of the second one of the strings of the one of the battery modules during charging.

[0048] Option 8. The battery system according to Option 1, wherein the switch control module is configured to: when a first SOC of a first one of the strings of one of the battery modules is greater than a second SOC of a second one of the strings of the one of the battery modules, set a first time period of the first one of the strings of the one of the battery modules to be longer than a second time period of the second one of the strings of the one of the battery modules during discharge.

[0049] Embodiment 9. The battery system of embodiment 1, wherein the switch control module is configured to selectively set a first period of the first of the phases to be longer than a second period of the second of the phases during charging based on the string SOC.

[0050] Embodiment 10. The battery system of embodiment 1, wherein the switch control module is configured to selectively set a first period of the first of the phases to be longer than a second period of the second of the phases during discharge based on the string SOC.

[0051] Embodiment 11. The battery system of embodiment 1, wherein the switch control module is configured to determine the period of the phase and the first period of the string based on minimizing an error between SOCs of battery cell strings.

[0052] Embodiment 12. The battery system of embodiment 11, wherein the error is the sum of squared differences between the SOCs of the strings.

[0053] Option 13. The battery system of Option 1, wherein each of the strings includes a plurality of battery cells connected in series.

[0054] Option 14. The battery system of Option 13, wherein the plurality of battery cells comprises four 3-volt battery cells.

[0055] Embodiment 15. The battery system of embodiment 1, wherein the switch control module is configured to control the switch so that one of the strings is not connected to both the first positive terminal and the second positive terminal at the same time.

[0056] Option 16. The battery system according to Option 1, wherein:

[0057] The first positive terminal is configured to output a first reference potential;

[0058] The second positive terminal is configured to output a second reference potential; and

[0059] The first reference potential is greater than the second reference potential.

[0060] Scheme 17. A method for a battery, comprising:

[0061] Determining a state of charge (SOC) of respective strings of battery cells of a battery, the battery comprising:

[0062] a first positive terminal;

[0063] Second positive terminal;

[0064] negative terminal;

[0065] switch;

[0066] Two battery modules, wherein each of the two battery modules includes three battery cell strings, the battery cell strings being configured to, at different times:

[0067] connected in series via a first one of the switches and connected to the first positive terminal;

[0068] connected in parallel via a second one of the switches and connected to the second positive terminal; and

[0069] disconnecting from both the first positive terminal and the second positive terminal;

[0070] Determine the time period of each stage based on SOC;

[0071] determining a first time period for connecting a plurality of the strings in parallel during one of the phases;

[0072] dividing the one of the phases into N periods of equal length each having N period end points, one of the N period end points being at the end of the one of the phases;

[0073] Selective reduction of N;

[0074] When the number of first time periods closest to the end of one of the N time period end points is at least a predetermined value, adjusting the first time period to the corresponding closest time period end point of the N time period end points; and

[0075] The switches are selectively actuated based on the duration of the phase and the duration of the battery cell string.

[0076] Option 18. The method according to Option 17, wherein the predetermined value is 2.

[0077] Option 19. The method according to Option 16, wherein selectively reducing N comprises selectively reducing N based on the number of first time periods closest to the one of the N time period end points.

[0078] Option 20. The method according to Option 16, wherein selectively reducing N comprises: decrementing N when the number of the first time periods closest to the one of the N time period end points is less than a predetermined value.

[0079] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the accompanying drawings.The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The present disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0081] Figure 1 is a functional block diagram of an example engine control system;

[0082] Figure 2 is a functional block diagram of an example battery system for a vehicle;

[0083] Figures 3A-3B is a schematic diagram of an example embodiment including a battery system;

[0084] Figure 4 is a functional block diagram of an example implementation of a battery module in an open circuit (X) configuration;

[0085] Figure 5 Includes an example illustration of a battery module in a series (S) configuration;

[0086] Figure 6 Includes an example illustration of battery modules in a parallel (P) configuration;

[0087] Figure 7 is a functional block diagram of an example switch control module;

[0088] Figure 8 including an example time sequence for operating in power mode during charging;

[0089] Figure 9 is a flow chart depicting an example method for balancing the SOC of battery strings and battery modules;

[0090] Figure 10 Includes example curves of SOC versus time for a battery string using string and module balancing during discharge;

[0091] Figure 11is a flow chart depicting an example method for setting periods of battery strings to increase computing efficiency and reduce switching; and

[0092] Figure 12 Includes example diagrams for setting time periods for battery strings.

[0093] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0094] A vehicle includes a battery having a first terminal on the battery housing for outputting a first operating voltage (e.g., 48 V) and a second output terminal on the housing for outputting a second operating voltage (e.g., 12 V). The battery includes a plurality of battery modules and a plurality of switches. Each battery module includes a plurality of battery strings, and each battery string includes a plurality of battery cells. The switches are configured to connect the strings together in series or to connect them individually to the terminals. The strings can also be disconnected from the first and second output terminals.

[0095] According to the present application, a model predictive control (MPC) module uses an estimate of the battery string's SOC and controls the switches to minimize SOC errors across the battery strings and battery modules. This ensures that each battery string is charged and discharged as evenly as possible and maximizes battery life.

[0096] To evenly distribute energy flow into and out of the modules and strings, the MPC module controls the switches to execute a series of phases, in which the modules alternately connect to the first and second output terminals. During some phases, individual strings within the module can vary their connection times within that phase. The MPC module can split the period during which a string is charging or discharging during a phase into two or more separate periods. This can be done, for example, to maintain approximately consistent characteristics (e.g., voltage and current) in and out of the battery. However, this increases switching and also requires more computational effort.

[0097] This application involves disabling split periods and setting the periods for battery module strings so that a predetermined minimum number of strings (e.g., two) are connected throughout the entire period when the battery module operates in parallel (P) mode. This improves computational efficiency (requiring less computational effort) and reduces switching. Reduced switching increases service life.

[0098] Now refer to Figure 1 , presents a functional block diagram of an example powertrain system 100. The powertrain system 100 of a vehicle includes an engine 102 that combusts an air / fuel mixture to produce torque. The vehicle may be non-autonomous or autonomous.

[0099] Air is drawn into the engine 102 through an intake system 108 . The intake system 108 may include an intake manifold 110 and a throttle valve 112 . For example only, the throttle valve 112 may include a butterfly valve having a rotatable blade. An engine control module (ECM) 114 controls a throttle actuator module 116 , which regulates opening of the throttle valve 112 to control air flow into the intake manifold 110 .

[0100] Air from the intake manifold 110 is drawn into cylinders of the engine 102. While the engine 102 includes multiple cylinders, for illustration purposes, a single representative cylinder 118 is shown. For example only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and / or 12 cylinders. The ECM 114 can instruct a cylinder actuator module 120 to selectively deactivate some of the cylinders under certain circumstances, which may improve fuel efficiency.

[0101] The engine 102 can operate using a four-stroke cycle or another suitable engine cycle. The four strokes of the four-stroke cycle described below will be referred to as the intake stroke, compression stroke, combustion stroke, and exhaust stroke. During each revolution of a crankshaft (not shown), two of these four strokes occur within the cylinder 118. Therefore, two crankshaft revolutions are required for the cylinder 118 to undergo all four strokes. For a four-stroke engine, one engine cycle may correspond to two crankshaft revolutions.

[0102] When the cylinder 118 is activated, air from the intake manifold 110 is drawn into the cylinder 118 through an intake valve 122 during the intake stroke. The ECM 114 controls a fuel actuator module 124, which regulates fuel injection to achieve a desired air / fuel ratio. Fuel may be injected into the intake manifold 110 at a central location or at multiple locations, such as near the intake valve 122 of each cylinder. In various implementations (not shown), fuel may be injected directly into the cylinder or into mixing chambers / ports associated with the cylinder. The fuel actuator module 124 may also halt fuel injection for deactivated cylinders.

[0103] The injected fuel mixes with air in the cylinder 118 to create an air / fuel mixture. During the compression stroke, a piston (not shown) within the cylinder 118 compresses the air / fuel mixture. The engine 102 may be a compression-ignition engine, in which case compression causes ignition of the air / fuel mixture. Alternatively, the engine 102 may be a spark-ignition engine, in which case a spark actuator module 126 energizes a spark plug 128 in the cylinder 118 based on a signal from the ECM 114, which ignites the air / fuel mixture. Some engine types, such as homogeneous charge compression ignition (HCCI) engines, may implement both compression and spark ignition. The timing of the spark may be specified relative to when the piston is at its topmost position, which is referred to as top dead center (TDC).

[0104] The spark actuator module 126 may be controlled by a timing signal that specifies how far before or after TDC to generate the spark. Because piston position is directly related to crankshaft rotation, operation of the spark actuator module 126 may be synchronized with crankshaft position. The spark actuator module 126 may disable or provide spark to deactivated cylinders.

[0105] During the combustion stroke, the combustion of the air / fuel mixture drives the piston downward, thereby driving the crankshaft. The combustion stroke can be defined as the time between the time the piston reaches TDC and the time when the piston returns to its bottommost position, which will be referred to as bottom dead center (BDC).

[0106] During the exhaust stroke, the piston moves up from BDC and expels the byproducts of combustion through an exhaust valve 130 . The byproducts of combustion are exhausted from the vehicle via an exhaust system 134 .

[0107] The intake valve 122 may be controlled by an intake camshaft 140 , while the exhaust valve 130 may be controlled by an exhaust camshaft 142 . In various implementations, multiple intake camshafts (including the intake camshaft 140 ) may control multiple intake valves (including the intake valve 122 ) for the cylinder 118 and / or may control the intake valves (including the intake valve 122 ) for multiple banks of cylinders (including the cylinder 118 ). Similarly, multiple exhaust camshafts (including the exhaust camshaft 142 ) may control multiple exhaust valves for the cylinder 118 and / or may control the exhaust valves (including the exhaust valve 130 ) for multiple banks of cylinders (including the cylinder 118 ). While camshaft-based valve actuation has been shown and discussed, a camless valve actuator may be implemented. While separate intake and exhaust camshafts are shown, a single camshaft having lobes for both the intake and exhaust valves may be used.

[0108] The cylinder actuator module 120 may deactivate the cylinder 118 by disabling opening of the intake valve 122 and / or the exhaust valve 130. The timing at which the intake valve 122 opens may be varied relative to piston TDC by an intake cam phaser 148. The timing at which the exhaust valve 130 opens may be varied relative to piston TDC by an exhaust cam phaser 150. A phaser actuator module 158 may control the intake and exhaust cam phasers 148 and 150 based on signals from the ECM 114. In various implementations, cam phasing may be omitted. Variable valve lift (not shown) may also be controlled by the phaser actuator module 158. In various other implementations, the intake valve 122 and / or the exhaust valve 130 may be controlled by actuators other than camshafts, such as electromechanical actuators, electrohydraulic actuators, electromagnetic actuators, etc.

[0109] The engine 102 may include zero, one, or more than one supercharging device that provides pressurized air to the intake manifold 110. For example, Figure 1 A turbocharger is shown including a turbocharger turbine 160 - 1 that is driven by exhaust gas flowing through the exhaust system 134. A supercharger is another type of boosting device.

[0110] The turbocharger also includes a turbocharger compressor 160 - 2 , which is driven by the turbocharger turbine 160 - 1 and compresses air leading to the throttle valve 112 . A wastegate (WG) 162 controls exhaust flow through and around the turbocharger turbine 160 - 1 . This wastegate may also be referred to as a turbine bypass valve. The wastegate 162 allows exhaust gas to bypass the turbocharger turbine 160 - 1, reducing the intake air compression provided by the turbocharger. The ECM 114 may control the turbocharger via a wastegate actuator module 164 . The wastegate actuator module 164 can adjust the turbocharger's boost pressure by controlling the opening of the wastegate 162 .

[0111] A cooler (e.g., a charge air cooler or an intercooler) can dissipate some of the heat contained in the compressed air charge, which is generated as the air is compressed. Although shown separated for illustration purposes, the turbocharger turbine 160-1 and the turbocharger compressor 160-2 can be mechanically linked to each other, placing the intake air in close proximity to the hot exhaust. The compressed air charge can absorb heat from components of the exhaust system 134.

[0112] The engine 102 may include an exhaust gas recirculation (EGR) valve 170 that selectively redirects exhaust gas back into the intake manifold 110. The EGR valve 170 may receive exhaust gas upstream of the turbocharger turbine 160-1 in the exhaust system 134. The EGR valve 170 may be controlled by an EGR actuator module 172.

[0113] Crankshaft position may be measured using a crankshaft position sensor 180 . Engine speed may be determined based on the crankshaft position measured using the crankshaft position sensor 180 . Engine coolant temperature (ECT) sensor 182 may be used to measure engine coolant temperature. ECT sensor 182 may be located within the engine 102 or at another location through which coolant is circulated, such as a radiator (not shown).

[0114] Pressure within the intake manifold 110 may be measured using a manifold absolute pressure (MAP) sensor 184. In various implementations, engine vacuum, which is the difference between ambient air pressure and the pressure within the intake manifold 110, may be measured. A mass air flow rate (MAF) sensor 186 may be used to measure the mass air flow rate into the intake manifold 110. In various implementations, the MAF sensor 186 may be located in a housing that also includes the throttle valve 112.

[0115] One or more throttle position sensors (TPS) 190 may be used to measure the position of the throttle valve 112. An intake air temperature (IAT) sensor 192 may be used to measure the temperature of air being drawn into the engine 102. One or more other sensors 193 may also be implemented. Other sensors 193 include an accelerator pedal position (APP) sensor, a brake pedal position (BPP) sensor, and may include a clutch pedal position (CPP) sensor (for example, in the case of a manual transmission). They may also include one or more other types of sensors. The APP sensor measures the position of the accelerator pedal within the vehicle's passenger compartment. The BPP sensor measures the position of the brake pedal within the vehicle's passenger compartment. The CPP sensor measures the position of the clutch pedal within the vehicle's passenger compartment. Other sensors 193 may also include one or more acceleration sensors that measure the vehicle's longitudinal (e.g., front / rear) acceleration and the vehicle's lateral (latitudinal) acceleration. An accelerometer is an example type of acceleration sensor, but other types of acceleration sensors may be used. The ECM 114 may use signals from these sensors to make control decisions for the engine 102.

[0116] The ECM 114 can communicate with a transmission control module 194, for example, to coordinate engine operation with gear shifting in a transmission 195. The ECM 114 can also communicate with a hybrid control module 196, for example, to coordinate operation of the engine 102 and an electric motor 198. While an example of an electric motor is provided, multiple electric motors may be implemented. The electric motor 198 may be a permanent magnet electric motor or another suitable type of electric motor that outputs a voltage based on back electromagnetic force (EMF) when freewheeling, such as a direct current (DC) electric motor or a synchronous electric motor. In various implementations, various functions of the ECM 114, the transmission control module 194, and the hybrid control module 196 may be integrated into one or more modules.

[0117] Each system that changes an engine parameter may be referred to as an engine actuator. Each engine actuator has an associated actuator value. For example, the throttle actuator module 116 may be referred to as an engine actuator, and the throttle opening area may be referred to as the actuator value. Figure 1 In the example, the throttle actuator module 116 achieves the throttle opening area by adjusting the angle of the blade of the throttle valve 112 .

[0118] The spark actuator module 126 may also be referred to as an engine actuator, and the corresponding actuator value may be the amount of spark advance relative to cylinder TDC. Other engine actuators may include the cylinder actuator module 120, the fuel actuator module 124, the phaser actuator module 158, the wastegate actuator module 164, and the EGR actuator module 172. For these engine actuators, the actuator values ​​may correspond to cylinder activation / deactivation sequencing, fueling rate, intake and exhaust cam phaser angles, target wastegate opening, and EGR valve opening, respectively.

[0119] The ECM 114 may control actuator values ​​to cause the engine 102 to output torque based on a torque request. The ECM 114 may determine the torque request, for example, based on one or more driver inputs (e.g., APP, BPP, CPP, and / or one or more other suitable driver inputs). The ECM 114 may determine the torque request, for example, using one or more functions or lookup tables that relate the driver inputs to the torque request.

[0120] Under some circumstances, the hybrid control module 196 controls the electric motor 198 to output torque, for example, to supplement the engine torque output. The hybrid control module 196 can also control the electric motor 198 to output torque for vehicle propulsion when the engine 102 is shut down.

[0121] The hybrid control module 196 applies electric power from the battery 208 to the electric motor 198 so that the electric motor 198 outputs positive torque. The battery is discussed further below. The electric motor 198 can output torque to, for example, the input shaft of the transmission 195, the output shaft of the transmission 195, or another component. The clutch 200 can be implemented to couple the electric motor 198 to the transmission 195 and decouple the electric motor 198 from the transmission 195. One or more gearing devices can be implemented between the output of the electric motor 198 and the input of the transmission 195 to provide one or more predetermined gear ratios between the rotation of the electric motor 198 and the rotation of the input of the transmission 195. In various embodiments, the electric motor 198 can be omitted.

[0122] The ECM 114 starts the engine 102 via the starter motor 202. The ECM 114 or another suitable module of the vehicle engages the starter motor 202 with the engine 102 for an engine start event. For example only, the ECM 114 may engage the starter motor 202 with the engine 102 upon receiving a key-on command. For example, a driver may input the key-on command by actuating one or more ignition keys, buttons, and / or switches of a vehicle or a key fob of the vehicle. The starter motor 202 may engage a flywheel coupled to a crankshaft or one or more other suitable components that drive the rotation of the crankshaft.

[0123] The ECM 114 can also start the engine in response to an autostart command during an autostop / start event or an engine start command in response to a sailing event. An autostop / start event includes shutting down the engine 102 when the vehicle is stopped, the driver has depressed the brake pedal, and the driver has not input a key OFF command. The autostart command can be generated when the engine 102 is shut down for an autostop / start event, for example, when the driver releases the brake pedal and / or depresses the accelerator pedal.

[0124] A coasting event may include the ECM 114 shutting down the engine 102 when the vehicle is moving (e.g., the vehicle speed is greater than a predetermined speed, such as 50 mph), the driver has not actuated the accelerator pedal, and the driver has not yet input a key-off command. An engine start command may be generated when the engine 102 is shut down for a coasting event, for example, when the driver depresses the accelerator pedal. The driver may input a key-off command, for example, by actuating one or more ignition keys, buttons, and / or switches, as discussed above.

[0125] A starter motor actuator (e.g., a solenoid) can actuate the starter motor 202 to engage the engine 102. For example only, the starter motor actuator can engage a starter pinion with a flywheel coupled to the crankshaft. In various implementations, the starter pinion can be coupled to the starter motor 202 via a drive shaft and a one-way clutch. A starter actuator module 204 controls the starter motor actuator and the starter motor 202 based on signals from a starter control module, as discussed further below. In various implementations, the starter motor 202 can remain engaged with the engine 102.

[0126] In response to a command to start the engine 102 (e.g., an autostart command, an engine start command for the end of a coasting event, or when a key-on command is received), the starter actuator module 204 supplies current to the starter motor 202 to start the engine 102. The starter actuator module 204 may also actuate the starter motor actuator to engage the starter motor 202 with the engine 102. After engaging the starter motor 202 with the engine 102, for example, to allow teeth to mesh, the starter actuator module 204 may supply current to the starter motor 202.

[0127] Applying current to the starter motor 202 drives rotation of the starter motor 202, and the starter motor 202 drives rotation of the crankshaft (eg, via a flywheel). The period during which the starter motor 202 drives the crankshaft to start the engine 102 may be referred to as engine cranking.

[0128] The starter motor 202 draws power from the battery 208 to start the engine 102. Once the engine 102 is running after the engine start event, the starter motor 202 is disengaged or disengaged from the engine 102, and the flow of current to the starter motor 202 may be interrupted. For example, the engine 102 may be considered running when the engine speed exceeds a predetermined speed (e.g., a predetermined idle speed). For example only, the predetermined idle speed may be approximately 700 revolutions per minute (rpm) or another suitable speed. When the engine 102 is running, the engine cranking may be considered complete.

[0129] Generator 206 converts the mechanical energy of engine 102 into alternating current (AC) power. For example, generator 206 may be coupled to the crankshaft (e.g., via gears or a belt) and convert the mechanical energy of engine 102 into AC power by applying a load to the crankshaft. Generator 206 rectifies the AC power into DC power and stores the DC power in battery 208. Alternatively, a rectifier external to generator 206 may be implemented to convert the AC power into DC power. Generator 206 may be, for example, an alternator. In various implementations, such as in the case of a belt alternator starter (BAS), starter motor 202 and generator 206 may be implemented together.

[0130] Figure 2 is a functional block diagram of an example battery system for a vehicle. Battery 208 has at least two output terminals and a negative terminal to provide at least two direct current (DC) operating voltages. By way of example only, battery 208 may have a first positive (e.g., 48 volts (V) nominal) terminal 210, a negative terminal 212, and a second positive (e.g., 12 V nominal) terminal 214. While examples of battery 208 having a nominal operating voltage of 48 V and a nominal operating voltage of 12 V are provided, battery 208 may have one or more other operating voltages.

[0131] The battery 208 includes a plurality of battery modules, such as a first battery module 224 - 1 , ..., and an Nth battery module 224 -N (“battery module 224 ”), where N is an integer greater than or equal to 2. In various embodiments, N may be equal to 2, 3, 4, 5, 6, 8, 10, or 12.

[0132] As follows about Figure 4 As discussed further, each of the battery modules 224 includes multiple battery strings. Each battery string can be independently replaceable. The ability to independently replace battery strings can enable the battery 208 to include a shorter warranty period and have lower warranty costs. The battery strings can also be independently isolable, for example, in the event of a fault in a battery string. In various embodiments, the battery 208 can have the form factor of a standard automotive-grade 12V battery.

[0133] Battery 208 includes a plurality of switches, such as a first switch 232 - 1 , ..., an Nth switch 232 -N (collectively referred to as “switches 232 ”). Switches 232 enable battery strings 224 to be connected in series, parallel, or a combination of series and parallel to provide a target output voltage and capacity at the output terminal.

[0134] The switch control module 240 controls the switches 232 to provide a desired output voltage and capacity at the output terminals. The switch control module 240 controls the switches 232 using model predictive control (MPC) to balance the state of charge (SOC) of the battery strings as closely as possible.

[0135] Figures 3A-3B 2 is a schematic diagram of an example battery system including battery 208. A group of battery strings can be connected in series (via switches in switch 232) to a first positive terminal 210 and a negative terminal 212 to provide a first nominal output voltage (e.g., 48 V) via first positive terminal 210. Individual battery strings in the battery string can be connected (via switches in switch 232) to a second positive terminal 214 and a negative terminal 212 to provide a second nominal output voltage (e.g., 12 V) via second positive terminal 214. The number of battery strings connected to first positive terminal 210 and second positive terminal 214 determines the portion of the total capacity of battery 208 that is available at each of the positive terminals.

[0136] like Figure 3B As shown in FIG, a first set of vehicle electrical components operates using one of the two or more operating voltages of the battery 208. For example, the first set of vehicle electrical components may be connected to the second positive terminal 214. The first set of vehicle electrical components may include, for example, but not limited to, the ECM 114 and other control modules of the vehicle, the starter motor 202, and / or other electrical loads, such as a first 12V load 304, a second 12V load 308, other control modules 312, a third 12V load 316, and a fourth 12V load 320. In various implementations, a switching device 324 may be implemented.

[0137] like Figure 3A As shown in FIG, a second set of vehicle electrical components operates using another of the two or more operating voltages of the battery 208. For example, the second set of vehicle electrical components can be connected to the first positive terminal 210. The second set of vehicle electrical components can include, for example, but not limited to, the generator 206 and various electrical loads, such as the 48 V load 328. The generator 206 can be controlled to charge the battery 208.

[0138] Each of the switches 232 may be an insulated gate bipolar transistor (IGBT), a field effect transistor (FET) (eg, a metal oxide semiconductor FET (MOSFET)), or another suitable type of switch.

[0139] Figure 4 is a functional block diagram of an example implementation of one of the battery modules 224 (numbered battery module 404) and a set of switches 232. Each of the battery modules 224 can be identical, and each set of switches 232 can be identical.

[0140] Battery module 404 includes three battery strings 408, 412, and 416. Battery strings 408-416 are identical and each includes four battery cells 420, 424, 428, and 432. Battery cells 420-432 are connected in series to provide a second operating voltage (e.g., 12 V). Each of battery cells 420-432 can be, for example, a 3 V battery or have another suitable voltage to provide the second operating voltage. Battery cells 420-432 can be, for example, lithium iron phosphate (LFP) battery cells or have another suitable chemistry.

[0141] The negative terminals of battery strings 408-416 are connected to negative terminal 212. When switches 436 and 440 are closed, the negative terminals of battery strings 408 and 412 are connected to negative terminal 212 via switches 436 and 440, respectively. Switches 436 and 440 can be opened to disconnect the negative terminals of battery strings 408 and 412 from negative terminal 212. The negative terminal of battery string 416 can be connected directly to negative terminal 212.

[0142] The positive terminal of battery string 416 is connected to the negative terminal of battery string 412, such that battery strings 412 and 416 are connected in series when switch 444 is closed. Switch 444 can be opened to disconnect the positive terminal of battery string 416 from the negative terminal of battery string 412. The positive terminal of battery string 412 is connected to the negative terminal of battery string 408, such that battery strings 412 and 408 are connected in series when switch 448 is closed. Switch 448 can be opened to disconnect the positive terminal of battery string 412 from the negative terminal of battery string 408.

[0143] Switches 452, 456, and 460 connect and disconnect the positive terminals of battery strings 408, 412, and 416, respectively, from a first bus (e.g., a 12 V bus) connected to second positive terminal 214. Switch 464 connects and disconnects the positive terminal of battery string 408 from a second bus (e.g., a 48 V bus) connected to first positive terminal 210.

[0144] The switch control module 240 controls the switching of the switches of each of the battery modules 224. At any given time, the switch control module 240 can actuate the switches associated with the battery modules so that the battery modules are in an open (X) configuration, a series (S) configuration, or a parallel (P) configuration. Figure 4 An example illustration of a battery module 404 is included that is in an open (X) configuration. When the battery module is in the open (X) configuration, all battery strings of the battery module are disconnected from both the first positive terminal 210 and the second positive terminal 214 .

[0145] Figure 5An example diagram includes a battery module 404 in a series (S) configuration. When the battery module is in the series (S) configuration, all of the battery strings of the battery module are connected in series and connected to the first positive terminal 210. This is accomplished by closing switches 444, 448, and 464 and opening all other switches 436, 440, 452, 456, and 460. When the battery module is in the series (S) configuration, none of the battery strings are connected to the second positive terminal 214.

[0146] Figure 6 An example diagram includes a battery module 404 in a parallel (P) configuration. When the battery module is in the parallel (P) configuration, all battery strings of the battery module are connected in parallel to the second positive terminal 214. This is accomplished by closing switches 452, 456, 460, 436, and 440 and opening all other switches 444, 448, and 464. When the battery module is in the parallel (P) configuration, none of the battery strings are connected to the first positive terminal 210.

[0147] Figure 7 is a functional block diagram of an example implementation of the switch control module 240. The switching module 704 applies a signal to (e.g., a gate terminal of) the switch 232 to control actuation of the switch 232 and control whether each of the battery modules 224 is in an open (X) state, a series (S) state, or a parallel (P) state.

[0148] The switching module 704 applies signals based on input from the model predictive control (MPC) module 708. The MPC module 708 determines the current power mode based on one or more operating parameters and generates an output to the switching module 704 based on the current power mode. The MPC module 708 further generates outputs based on constraints 712 set by the constraint module 716. Examples of constraints 712 include: a battery string cannot be connected to the first positive terminal 210 or the second positive terminal 214 when its battery modules are in X connection; a battery string cannot be connected to both the first positive terminal 210 and the second positive terminal 214 simultaneously; and a battery string cannot be connected to the second positive terminal 214 multiple times when the battery modules are to be connected in parallel (P) mode. The duration of a phase can be constrained to meet the demand at the first positive terminal 210. The connection duration of each string can be limited (constrained) to the end of the phase. The number of channels (battery strings) per battery module can be constrained to meet the demand at the second positive terminal 210.

[0149] One, more than one, or all of the constraints 712 may be fixed. In various implementations, one or more of the constraints 712 may be variable. The constraint module 716 may set the variable constraints based on one or more operating parameters 714. Examples of operating parameters 714 include, for example, the current power mode, the predicted duration of the current power mode, and other example operating parameters.

[0150] The state of charge (SOC) module 718 determines the current state of charge (SOC) 720 for each of the battery strings. In other words, the SOC module 718 determines the current SOC 720 for each battery string. The SOC module 718 may determine the current SOC of the battery string based on, for example, at least one of the voltage across the battery string and the current flowing into or out of the battery string. In various embodiments, the SOC module 718 may determine the SOC of the battery based on the impedance of the battery, for example, to more accurately correlate voltage and current to SOC. The SOC module 718 may determine the current SOC of the battery string using at least one of an equation and a lookup table that correlates voltage and / or current to SOC. The SOC module 718 does this for each battery string. The voltage and current of the battery string 724 may be measured using voltage and current sensors, respectively.

[0151] The MPC module 708 controls the switching of the switches (via the switching module 704) to minimize the error (e.g., the sum of squared differences (or errors)) between the SOCs of the battery strings for the current power mode. The MPC module 708 can further control the switching of the switches based on the current output demand via the first positive terminal 210 and the second positive terminal 214 and the predicted output demand from the first positive terminal 210 and the second positive terminal 214. The current output demand and the predicted output demand are illustrated by 728.

[0152] To balance the SOC of the strings 720, MPC is used. The MPC module 708 sets the duration of each phase (Phase 1, Phase 2, and Phase 3), the number of battery strings connected when in P-mode, and the duration that each battery string is connected in P-mode. Each power mode has an associated set of configurations (X-mode, P-mode, or S-mode) for the battery modules 224 used for that power mode. A table illustrating the power modes and battery module modes for each phase is provided below. The MPC module 708 repeatedly cycles through the phases (Phase 1, Phase 2, Phase 3, then back to Phase 1, etc.) until the power mode is changed.

[0153] Power Mode Phase 1 Phase 2 Phase 3 Condition 1 (XXX mode) XXX XXX XXX OFF 2 (XXP mode) XXP PXX XPX 12 V sleep mode 3 (XXS mode) XXS SXX XSX 48 V low power mode with diagnostics 4 (XPP mode) XPP PXP PPX 12V medium power mode with diagnostics 5 (SXP mode) SXP PSX XPS Low power 2 voltage mode with diagnostics 6 (XSS mode) XSS SXS SSX 48 V medium power with diagnostics 7 (PPP mode) PPP PPP PPP 12 V high power cranking mode 8 (PPS mode) PPS SPP PSP Normal 2 voltage mode 9 (PSS mode) PSS SPS SSP Normal 2 voltage mode 10 (SSS mode) SSS SSS SSS 48 V high power mode

[0154] In the example table above, the battery module mode of the corresponding battery module is provided for each phase. For example, when in power mode 5 (SXP mode), during the first phase (Phase 1), the first battery module operates in series (S) mode, the second battery module operates in open (X) mode, and the third battery module operates in parallel (P) mode. During the second phase (Phase 2) of power mode 5, the first battery module operates in parallel (P) mode, the second battery module operates in series (S) mode, and the third battery module operates in open (X) mode. During the third phase (Phase 3) of power mode 5, the first battery module operates in open (X) mode, the second battery module operates in parallel (P) mode, and the third battery module operates in series (S) mode.

[0155] The MPC module 708 sets the duration (length) of each of the first, second, and third phases to optimize the SOC balance of each battery string. For example, if the battery string of one battery module (e.g., on average) has a lower SOC than the other two battery modules, during charging, the MPC module 708 may set one or more phases in which the one battery module operates in parallel (P) mode to be longer than the one or more phases in which the other two battery modules operate. This will cause the SOC of the other two battery modules to increase less than the SOC of the one battery module, resulting in a more balanced SOC across the battery modules. During discharging, if the battery string of one battery module (e.g., on average) has a lower SOC than the other two battery modules, the MPC module 708 may set one or more phases in which the one battery module operates in parallel (P) mode to be shorter than the one or more phases in which the other two battery modules operate. This will cause the SOC of the other two battery modules to decrease more than the SOC of the one battery module, resulting in a more balanced SOC across the battery modules.

[0156] The MPC module 708 also sets the duration (length / period) of each phase in which each battery string is connected to the second positive terminal 214 to balance the individual SOCs of the battery strings in each module. For example, during charging, when one battery string in a battery module has a lower SOC than the other battery strings in that battery module, the MPC module 708 may set the duration of the connection of that one battery string to the second positive terminal 214 to be longer than the duration of the connection of the other battery strings in the battery module. This causes the SOC of the one battery string in the battery module to increase more than the SOCs of the other battery strings in the battery module, resulting in a more balanced SOC within the battery module. The MPC module 708 performs this operation for each battery module. During discharging, when one battery string in a battery module has a lower SOC than the other battery strings in that battery module, the MPC module 708 may set the duration of the connection of that one battery string to the second positive terminal 214 to be shorter than the duration of the connection of the other battery strings in the battery module. This causes the SOC of the one battery string in the battery module to decrease less than the SOCs of the other battery strings in the battery module, resulting in a more balanced SOC within the battery module. The MPC module 708 does this for each battery module.

[0157] Figure 8 An example time sequence is included for operation in power mode 5 (SXP) during charging. 804 is the first phase (Phase 1), 808 is the second phase (Phase 2), and 812 is the third phase (Phase 3). As used herein, MNO mode may mean that the first battery module operates in mode M, the second battery module operates in mode N, and the third battery module operates in mode O, where M, N, and O are each one of parallel (P), series (S), or open (X). For example, the first phase includes SXP mode, where the first battery module operates in series (S) mode, the second battery module operates in open (X) mode, and the third battery module operates in parallel (P) mode. The second phase includes operation in PSX mode, where the first battery module operates in parallel (P) mode, the second battery module operates in series (S) mode, and the third battery module operates in open (X) mode. The third stage includes operation in XPS mode, wherein the first battery module operates in open circuit (X) mode, the second battery module operates in parallel (P) mode, and the third battery module operates in series (S) mode.

[0158] exist Figure 8In the example shown in FIG2 , the MPC module 708 sets the duration of the second phase to be longer than the duration of the third phase and sets the duration of the third phase to be longer than the duration of the first phase. This allows the battery string of the first battery module (which is connected in parallel (P) mode in the second phase) to be charged more than the other battery modules, and allows the battery string of the second battery module (which is connected in parallel (P) mode in the third phase) to be charged more than the battery string of the third battery module. The third battery module is operated in parallel (P) mode in the first phase.

[0159] During the first stage 804, the MPC module 708 connects the third battery string 824 of the third battery module to the second positive terminal 214 for a duration that is shorter than the first battery string 816 and the second battery string 820 of the third battery module. This allows the first battery string 816 and the second battery string 820 of the third battery module to be charged more than the third battery string 824 of the third battery module to balance the SOCs of the first battery string 816, the second battery string 820, and the third battery string 824 of the third battery module.

[0160] During the second phase 808, the MPC module 708 connects the third battery string 824 of the first battery module to the second positive terminal 214 for a duration that is less than the first battery string 816 and the second battery string 820 of the first battery module. This allows the first battery string 816 and the second battery string 820 of the first battery module to be charged more than the third battery string 824 of the first battery module to balance the SOCs of the first battery string 816, the second battery string 820, and the third battery string 824 of the first battery module.

[0161] During the third stage 812, the MPC module 708 connects the third battery string 824 of the second battery module to the second positive terminal 214 for a duration that is shorter than the first battery string 816 and the second battery string 820 of the second battery module. This allows the first battery string 816 and the second battery string 820 of the second battery module to be charged more than the third battery string 824 of the second battery module to balance the SOCs of the first battery string 816, the second battery string 820, and the third battery string 824 of the second battery module.

[0162] Assuming the power mode has not changed, control then returns to Phase 1. In other words, control continues from Phase 1 to Phase 2 to Phase 3, after which Phases 1-3 are repeated in the same order.

[0163] Although the diagram shows the charging Figure 8, but similar content also applies to the case of discharge. For example, if the SOC of the third strings of the first, second, and third battery modules is lower than the SOC of the first and second strings of the first to third battery modules, respectively, the MPC module 708 may connect the third strings of the first to third battery modules to the second positive terminal 214 for a shorter period than the first and second strings of the first to third battery modules during the corresponding phase. This causes the third string to discharge less than the first and second strings and balances the SOCs of the battery strings.

[0164] Figure 9 is a flow chart depicting an example method for balancing the SOCs of the battery strings of the battery modules of battery 208. Control begins at 904, where the SOC module 718 determines the SOC of the battery strings (first, second, and third) of each of the battery modules 324 (first, second, and third) of battery 208. At 908, the SOC module 718 may determine the SOCs of the battery modules (first, second, and third) based on the battery strings of the battery modules. For example, the SOC module 718 may determine the SOC of the first battery module based on an average of the SOCs of the battery strings (first, second, and third) of the first battery module. The SOC module 718 may determine the SOC of the second battery module based on an average of the SOCs of the battery strings (first, second, and third) of the second battery module. The SOC module 718 may determine the SOC of the third battery module based on an average of the SOCs of the battery strings (first, second, and third) of the third battery module.

[0165] At 912, the MPC module 708 determines a power mode. The MPC module 708 can select one of the above power modes, such as SXP mode, XPP mode, XXP mode, or another one of the above modes.

[0166] At 916, the MPC module 708 determines a phase duration based on the power mode and the SOC of the battery module. For example, when the SOC of a battery module is less than the SOC of other battery modules, the MPC module 708 may set the duration of the phase when the battery module is connected in parallel (P) mode to be shorter than the duration of other phases. The MPC module 708 uses MPC to determine the phase duration.

[0167] At 920, the MPC module 708 determines the (initial) duration (period) for each string of each battery module to be connected within the phase. For example, during charging, when a battery string has a lower SOC than other battery strings, the MPC module 708 may charge that battery string longer than the other battery strings. During discharging, when a battery string has a higher SOC than other battery strings, the MPC module 708 may discharge the battery longer than the other battery strings. The MPC module 708 uses MPC to determine the battery string duration. The MPC module 708 determines the final duration (period) based on the initial period, as discussed further below.

[0168] In various embodiments, 912 and 916 may be performed simultaneously by the MPC module 708. When all string SOCs are equal, the optimization cost criterion may be zero, and may become larger as the difference between the SOCs increases. One possible formulation for such a cost criterion is a weighted sum of the squared differences between adjacent pairs of SOCs in a cycle chain including all strings, taken over a planned horizon consisting of one or more complete cycles through the phase. To avoid overheating any string, an additional penalty may be added, such as a cost on the total connection time of the string. The variables in the optimization are the duration of the phase and the duration for which each string is connected in the P configuration. Minimization of the cost criterion is subject to constraint 712. Given the output demand and forecast 728, the cost criterion may be evaluated by the MPC module 708 for any set of connection durations. The solution to the minimization problem is a set of phase durations and string connection durations that most closely balances the string SOCs over the planned horizon, subject to constraint 712 and taking into account any additional penalty terms.

[0169] At 924, the switching module 704 actuates the switch 232 based on the power mode, the phase duration, and the battery string duration. Control returns to 904 for the next cycle.

[0170] Figure 10 Included is an example graph of the SOC 1004 of a battery string during discharge according to string and module balancing discussed herein over time 1008. As illustrated, although the SOCs are initially different, the SOCs become approximately equal relatively quickly.

[0171] To implement a set of time durations that minimize the cost criterion, these time durations are post-processed into a sequence of timed events for opening and closing the switches. Figure 11 is a flow chart depicting an example method for setting battery string time periods to increase computing efficiency and reduce switching. Figure 12 Including about Figure 11 Example illustration of the concept of .

[0172] Control begins at 1104 where the MPC module 708 determines the phase periods and the initial periods for the battery strings for each phase as discussed above. For phase 1202, an example initial period for a battery string of battery modules operating in parallel (P) mode is given by Figure 12 1204. The third battery string of the battery module will be connected during periods 1208 and 1212 of stage 1202. The second battery string of the battery module will be connected during periods 1216 and 1220 of stage 1202. The first battery string of the battery module will be connected during period 1224 of stage 1202.

[0173] At 1108, if the string is to be connected during multiple periods of a phase, the MPC module 708 combines the multiple periods of the phase into one continuous period of length equal to the sum of the multiple periods. Figure 12 1208 and 1212 of the third battery string, where the time periods 1208 and 1212 of the third battery string are added together to produce a time period 1228. The time periods 1216 and 1220 of the second battery string are also added together to produce a time period 1232.

[0174] At 1112, the MPC module 708 initializes the counter value N to a predetermined value greater than 2. Figure 12 In the example of , the MPC module 708 initializes N to 4. At 1116, the MPC module 708 divides the phase into N+1 equal-length periods. For an example of N=4, the N+1 equal-length periods are given by Figure 12 1236, 1240, 1244, 1248 and 1252 in FIG.

[0175] At 1120, the MPC module 708 compares the battery string's time period to the boundaries of the N+1 equal-length time periods to determine the closest time period boundary for each battery string period. The last of the N+1 equal-length time periods (e.g., 1252) has a time period boundary at the end of stage 1202. The MPC module 708 determines the closest time period boundary for each battery string period. For example, time period 1228 is closest to time period boundary 1256, time period 1232 is closest to time period boundary 1260 (at the end of stage 1202), and time period 1232 is closest to time period boundary 1264.

[0176] At 1124, MPC module 708 determines how many periods of the battery string are closest to the end of phase 1202 (1260), and determines whether the number of periods closest to the end of phase 1202 is greater than or equal to a predetermined value. The predetermined value is scalable, greater than zero, and may be, for example, 2. At 1212, only period 1232 is closest to the end of phase 1202. If 1124 is false, MPC module 708 decrements counter value N by 1 (e.g., sets N=N-1) at 1128, and control returns to 1116. This results in one fewer period of equal length, as illustrated by 1268, which includes two fewer periods of equal length than 1212. Another iteration of 1116-1128 is performed between 1212 and 1268.

[0177] If 1124 is true, control continues with 1132. At 1132, the MPC module 708 adjusts the periods of the battery strings to the nearest period boundary to produce the final period of the phase of the battery string. Figure 12 In the example of , the MPC module 708 decreases the period 1228 of the third string to the period boundary 1270, increases the period of the second string to the period boundary 1260, and increases the period of the first string to the period boundary 1260. The adjusted period is Figure 12 1272 of FIG. Setting the battery string period in the manner described herein reduces the computational workload (increases computational efficiency) and reduces the switching of switches. Reducing switching increases battery life. As discussed above, control continues with 924. Although Figure 11 The example is shown as ending, control returns to 1104 and is only shown for one stage. Figure 11 One iteration can be performed for each stage.

[0178] The foregoing description is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, as other modifications will become apparent upon study of the drawings, the specification, and the appended claims. It should be understood that one or more steps within the method can be performed in a different order (or simultaneously) without changing the principles of the present disclosure. In addition, although each of the embodiments is described above as having certain features, any one or more of those features described with reference to any embodiment of the present disclosure may be implemented in and / or combined with features of any of the other embodiments, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the permutation of one or more embodiments with each other remains within the scope of the present disclosure.

[0179] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." Unless explicitly described as "direct," when describing a relationship between a first and a second element in the above disclosure, the relationship can be a direct relationship with no other intervening elements between the first and second elements, but can also be an indirect relationship with one or more intervening elements between the first and second elements (either spatially or functionally). As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean a logical (A or B or C) using a non-exclusive logical "OR" and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C."

[0180] In a diagram, the direction of an arrow, as represented by an arrowhead, generally indicates the flow of information (e.g., data or instructions) of interest to the diagram. For example, when component A and component B exchange various information, but the information transmitted from component A to component B is relevant to the diagram, an arrow may point from component A to component B. This unidirectional arrow does not imply that no other information is transmitted from component B to component A. Furthermore, for information transmitted from component A to component B, component B may send a request for the information or an acknowledgment of receipt of the information to component A.

[0181] In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to, be part of, or include: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

[0182] A module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module of the present disclosure may be distributed across multiple modules connected via the interface circuits. For example, multiple modules may allow for load balancing. In another example, a server (also known as a remote or cloud) module may perform some functionality on behalf of a client module.

[0183] As used above, the term "code" may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term "shared processor circuit" encompasses a single processor circuit that executes some or all code from multiple modules. The term "group processor circuit" encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. Reference to multiple processor circuits encompasses multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or combinations of the above. The term "shared memory circuit" encompasses a single memory circuit that stores some or all code from multiple modules. The term "group memory circuit" encompasses a memory circuit that, in combination with additional memory, stores some or all code from one or more modules.

[0184] The term "memory circuit" is a subset of the term "computer-readable medium." As used herein, the term "computer-readable medium" does not encompass transitory electrical or electromagnetic signals propagated through a medium (e.g., on a carrier wave); the term "computer-readable medium" is therefore considered to be both tangible and non-transitory. Non-limiting examples of non-transitory, tangible computer-readable media are non-volatile memory circuits (e.g., flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (e.g., static random access memory circuits or dynamic random access memory circuits), magnetic storage media (e.g., analog or digital magnetic tape or hard drives), and optical storage media (e.g., CDs, DVDs, or Blu-ray discs).

[0185] The apparatus and method described in this application may be implemented in part or in whole by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions implemented in a computer program. The above-mentioned functional blocks, flow chart components and other elements serve as software specifications, which can be converted into computer programs through routine work by a skilled technician or programmer.

[0186] A computer program includes processor-executable instructions stored on at least one non-transitory, tangible, computer-readable medium. A computer program may also include or rely on stored data. A computer program may include a basic input / output system (BIOS) that interacts with the hardware of a special-purpose computer, device drivers that interact with specific devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, and the like.

[0187] A computer program may include: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated by a compiler from source code, (iv) source code executed by an interpreter, (v) source code compiled and executed by a just-in-time compiler, etc. By way of example only, the source code may be written using syntax from languages ​​including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language Revision 5), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.

Claims

1. A battery system comprising: a first positive terminal; Second positive terminal; negative terminal; switch; Two battery modules, wherein each of the two battery modules includes three battery cell strings, the battery cell strings being configured to, at different times: connected in series via a first one of the switches and connected to the first positive terminal; connected in parallel via a second one of the switches and connected to the second positive terminal; and disconnecting from both the first positive terminal and the second positive terminal; and A switch control module, wherein the switch control module is configured to: determining the state of charge of the battery cell strings respectively; determining the duration of each phase based on the state of charge; determining a first time period during one of the phases for connecting a plurality of the strings in parallel; dividing the one of the phases into N time periods of equal length, each having N time period end points, one of the N time period end points being at the end of the one of the phases; Selective reduction of N; When the number of first time periods closest to the end of one of the N time period end points is at least a predetermined value, adjusting the first time period to the corresponding closest time period end point of the N time period end points; and The switches are selectively actuated based on the duration of the phase and the duration of the battery cell string.

2. The battery system according to claim 1, wherein: The preset value is 2.

3. The battery system according to claim 1, wherein: The switch control module is configured to selectively decrease N based on a number of first time periods closest to the one of the N time period end points.

4. The battery system according to claim 1, wherein: The switch control module is configured to decrement N when the number of the first time periods closest to the one of the N time period end points is less than a predetermined value.

5. The battery system according to claim 4, wherein: The switch control module is configured to decrement N by one.

6. The battery system according to claim 1, wherein: The switch control module is configured to combine the two first time periods in which one of the strings is connected in parallel during the one of the phases, when the two first time periods in which one of the strings is connected in parallel are separated by a time period in which the one of the strings is not connected in parallel, so that the two first time periods are adjacent.

7. The battery system according to claim 1, wherein: The switch control module is configured to set a first time period of the first one of the strings of one of the battery modules to be longer than a second time period of the second one of the strings of the one of the battery modules during charging when a first state of charge of the first one of the strings of the one of the battery modules is less than a second state of charge of the second one of the strings of the one of the battery modules.

8. The battery system according to claim 1, wherein: The switch control module is configured to set a first time period of the first one of the strings of one of the battery modules to be longer than a second time period of the second one of the strings of the one of the battery modules during discharge when a first state of charge of the first one of the strings of the one of the battery modules is greater than a second state of charge of the second one of the strings of the one of the battery modules.

9. The battery system according to claim 1, wherein: The switch control module is configured to selectively set a first period of a first one of the phases to be longer than a second period of a second one of the phases during charging based on a state of charge of the string.

10. The battery system according to claim 1, wherein: The switch control module is configured to selectively set a first period of a first one of the phases to be longer than a second period of a second one of the phases during discharge based on a state of charge of the string.

11. The battery system according to claim 1, wherein: The switch control module is configured to determine a period of the phase and a first period of the string based on minimizing an error between states of charge of the battery cell strings.

12. The battery system according to claim 11, wherein: The error is the sum of the squared differences between the states of charge of the strings.

13. The battery system according to claim 1, wherein: Each of the strings includes a plurality of battery cells connected in series.

14. The battery system according to claim 13, wherein: The plurality of battery cells includes four 3 volt battery cells.

15. The battery system according to claim 1, wherein: The switch control module is configured to control the switch so that one of the strings is not connected to both the first positive terminal and the second positive terminal simultaneously.

16. The battery system according to claim 1, wherein: The first positive terminal is configured to output a first reference potential; The second positive terminal is configured to output a second reference potential; and The first reference potential is greater than the second reference potential.

17. A method for a battery, comprising: Determining a state of charge of respective strings of battery cells of a battery, the battery comprising: a first positive terminal; Second positive terminal; negative terminal; switch; Two battery modules, wherein each of the two battery modules includes three battery cell strings, the battery cell strings being configured to, at different times: connected in series via a first one of the switches and connected to the first positive terminal; connected in parallel via a second one of the switches and connected to the second positive terminal; and disconnecting from both the first positive terminal and the second positive terminal; determining the duration of each phase based on the state of charge; determining a first time period during one of the phases for connecting a plurality of the strings in parallel; dividing the one of the phases into N time periods of equal length, each having N time period end points, one of the N time period end points being at the end of the one of the phases; Selective reduction of N; When the number of first time periods closest to the end of one of the N time period end points is at least a predetermined value, adjusting the first time period to the corresponding closest time period end point of the N time period end points; and The switches are selectively actuated based on the duration of the phase and the duration of the battery cell string.

18. The method according to claim 17, wherein: The preset value is 2.

19. The method according to claim 17, wherein Selectively decreasing N includes selectively decreasing N based on a number of first periods closest to the one of the N period end points.

20. The method according to claim 17, wherein Selectively decreasing N includes decrementing N when the number of first time periods closest to the one of the N time period end points is less than a predetermined value.

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