Method for improving charging speed by using vehicle-mounted alternating current power generation

Abstract

A vehicle includes an electrical system that performs a method of charging a battery of the vehicle. An electrical system includes a battery, an inverter coupled to the battery via a positive bus, a first contactor within the inverter connecting the battery to the inverter via the positive bus, a charging port for connecting the positive bus to a charging station for receiving a baseline charging current from the charging station, a diode for preventing reverse flow of current from the electrical system to the charging station, and a processor. The processor is configured to control the first contactor to generate a ripple current in the positive bus line, where the ripple current is superimposed on a baseline charging current to obtain a combined charging current, where the combined charging current is used to charge the battery.

Description

Technical Field

[0001] This subject matter relates to the charging of electric vehicles, and more specifically, to systems and methods for increasing charging speed. Background Technology

[0002] Electric vehicles require periodic charging to replenish their batteries. Charging typically involves a constant current phase followed by a constant voltage phase. The constant voltage phase can take an undesirable long time. In particular, the charging speed of lithium-ion batteries is limited by the occurrence of lithium plating, especially at lower temperatures. Pulse charging has been shown to improve charging speed. However, this requires generating the ripple current from the charging source (which may or may not be equipped for ripple current generation) or by installing additional hardware into the vehicle. Therefore, it is desirable to use the vehicle's existing circuitry to generate the ripple current. Summary of the Invention

[0003] In one exemplary embodiment, a method for charging a vehicle battery is disclosed. A baseline charging current is received from a charging station coupled to an electrical system connected to the vehicle, the electrical system including a battery, an inverter, and a positive bus (positive bus line) connecting the battery to the inverter and the charging station. The inverter includes a first contactor for connecting the battery and the inverter along the positive bus. The first contactor is controlled to generate a ripple current on the positive bus line. The ripple current is superimposed on the baseline charging current to obtain a combined charging current. The battery is charged using the combined charging current.

[0004] In addition to one or more features described herein, the charging operation includes a constant current phase, and the method further includes charging the battery using a combined charging current during the constant current phase.

[0005] In addition to one or more features described herein, the electrical system includes a second contactor between the midpoint of the positive bus and the branch of the inverter, and the method further includes controlling the first contactor and the second contactor to generate the ripple current.

[0006] In addition to one or more features described herein, the charging operation includes a constant current phase and a constant voltage phase, and the method also includes charging the battery with a combined charging current to reduce the duration of the constant voltage phase.

[0007] In addition to one or more features described herein, the method also includes controlling the amplitude of the ripple current to perform at least one of suppressing electroplating at the battery and heating the battery.

[0008] In addition to one or more features described herein, the method also includes applying heat to the battery via at least one of an external heat source and a ripple current.

[0009] In addition to one or more features described herein, the method also includes providing a baseline current at a first power, superimposing a ripple current on the baseline current to generate a combined charging current at the first power, and increasing the combined charging current from the first power to a second power greater than the first power.

[0010] In another exemplary embodiment, an electrical system for a vehicle is disclosed. The electrical system includes a battery, an inverter connected to the battery via a positive bus, a first contactor within the inverter connecting the battery to the inverter via the positive bus, a charging port for connecting the positive bus to a charging station to receive a baseline charging current from the charging station, and a processor. The processor is configured to control the first contactor to generate a ripple current in the positive bus, wherein the ripple current is superimposed on the baseline charging current to obtain a combined charging current for charging the battery.

[0011] In addition to one or more features described herein, the charging operation includes a constant current phase, and the processor is also configured to charge the battery using a combined charging current during the constant current phase.

[0012] In addition to one or more features described herein, the electrical system includes a second contactor between the midpoint of the positive bus and the branch of the inverter, and the processor is further configured to control the first and second contactors to generate the ripple current.

[0013] In addition to one or more features described herein, the charging operation includes a constant current phase and a constant voltage phase, and the processor is also configured to charge the battery using a combined charging current to reduce the duration of the constant voltage phase.

[0014] In addition to one or more features described herein, the processor is also configured to control the amplitude of the ripple current to perform suppression of plating at the battery site and heating of at least one of the batteries.

[0015] In addition to one or more features described herein, heat is applied to the battery via at least one of an external heat source and ripple current.

[0016] In addition to one or more features described herein, the processor is also configured to: provide the baseline current at a first power, superimpose the ripple current on the baseline current to generate the combined charging current of the first power, and increase the combined charging current from the first power to a second power greater than the first power.

[0017] In yet another exemplary embodiment, a vehicle is disclosed. The vehicle includes an electrical system. The electrical system includes a battery, an inverter connected to the battery via a positive bus, a first contactor within the inverter connecting the battery to the inverter via the positive bus, a charging port for connecting the positive bus to a charging station for receiving a baseline charging current from the charging station, a diode for preventing current from flowing back from the electrical system to the charging station, and a processor. The processor is configured to control the first contactor to generate a ripple current in the positive bus line, wherein the ripple current is superimposed on the baseline charging current to obtain a combined charging current, wherein the combined charging current is used to charge the battery.

[0018] In addition to one or more features described herein, the charging operation includes a constant current phase, and the processor is also configured to charge the battery using a combined charging current during the constant current phase.

[0019] In addition to one or more features described herein, the electrical system includes a second contactor between the midpoint of the positive bus line and the branch of the inverter, and the processor is further configured to control the first and second contactors to generate the ripple current.

[0020] In addition to one or more features described herein, the charging operation includes a constant current phase and a constant voltage phase, and the processor is also configured to charge the battery using a combined charging current to reduce the duration of the constant voltage phase.

[0021] In addition to one or more features described herein, the processor is also configured to control the amplitude of the ripple current to perform suppression of plating at the battery site and heating of at least one of the batteries.

[0022] In addition to one or more features described herein, the processor is also configured to: provide the baseline current at a first power, superimpose the ripple current on the baseline current to generate the combined charging current of the first power, and increase the combined charging current from the first power to a second power greater than the first power.

[0023] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent when taken in conjunction with the accompanying drawings and the following detailed description. Attached Figure Description

[0024] Other features, advantages, and details appear by way of example only in the following detailed description, which is described in detail with reference to the accompanying drawings, wherein:

[0025] Figure 1 An embodiment of a vehicle according to an exemplary embodiment is shown;

[0026] Figure 2 An illustrative embodiment is shown. Figure 1 The vehicle's electrical system;

[0027] Figure 3 A circuit illustrating the charging operation of a vehicle is shown in an embodiment;

[0028] Figure 4 A graph illustrating the relationship between current and time during charging operation is shown.

[0029] Figure 5 It is a graph showing the relationship between charging current and state of charge for different charging operations;

[0030] Figure 6 It is a diagram of an electrical system with multiple inverters and motors;

[0031] Figure 7 The graph shows the charging power over time.

[0032] Figure 8 A graph showing the state of charge (SOC) over time is shown.

[0033] Figure 9 It is a graph showing the low-amplitude ripple current that can be used for charging;

[0034] Figure 10 It is a graph showing the intermediate range of amplitude ripple current that can be used for charging;

[0035] Figure 11 It is a graph showing the high-amplitude ripple current that can be used for charging;

[0036] Figure 12 This is a diagram illustrating the heating and pulse charging strategies;

[0037] Figure 13 This is a graph showing the charging power of various charging methods used for cold batteries; and

[0038] Figure 14 It is a graph showing the battery temperature for various charging methods used for cold batteries. Detailed Implementation

[0039] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or use. It should be understood that throughout the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0040] According to an exemplary embodiment, Figure 1An embodiment of vehicle 10 is shown, which includes a body 12 that at least partially defines a passenger compartment 14. The body 12 also supports various vehicle subsystems, including a propulsion system 16 and other subsystems to support the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, etc.

[0041] Vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or any other vehicle. In this embodiment, vehicle 10 is an electric vehicle that includes multiple motors and / or drive systems. Any number of drive units may be included, such as one or more drive units for applying torque to the front wheels (not shown) and / or the rear wheels (not shown). The drive units are controllable to operate vehicle 10 in various operating modes, such as normal mode, high-performance mode (where additional torque is applied), all-wheel drive (“AWD”), front-wheel drive (“FWD”), rear-wheel drive (“RWD”), etc.

[0042] For example, propulsion system 16 is a multi-drive system, comprising a front drive unit 20 for driving the front wheels and a rear drive unit for driving the rear wheels. The front drive unit 20 includes a front motor 22 and a front inverter 24 (e.g., a front power inverter module or FPIM), as well as other components such as a cooling system. The left rear drive unit 30L includes a left rear motor 32L and a left rear inverter 34L. The right rear drive unit 30R includes a right rear motor 32R and a right rear inverter 34R. The front inverter 24, left rear inverter 34L, and right rear inverter 34R (e.g., a power inverter unit or PIM) each convert direct current (DC) power from the high-voltage (HV) battery system 40 into multiphase (e.g., two-phase, three-phase, six-phase, etc.) alternating current (AC) power to drive the front motor 22, left rear motor 32L, and right rear motor 32R.

[0043] like Figure 1 As shown, the drive system has a separate electric motor. However, the embodiments are not limited to this. For example, instead of a separate motor, multiple drives can be provided by a single machine with multiple physically independent sets of windings.

[0044] For example Figure 1 As shown, the drive system is configured such that the front motor 22 drives the front wheels (not shown), and the left rear motor 32L and right rear motor 32R drive the rear wheels (not shown). However, the embodiment is not limited to this, as any number of drive systems and / or motors (e.g., a motor driving each wheel, dual motors per axle, etc.) can be present in various locations. Furthermore, the embodiment is not limited to a dual drive system, as it can be used with vehicles having any number of motors and / or power inverters.

[0045] In the propulsion system 16, the front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R are electrically connected to the battery system 40. The battery system 40 may also be electrically connected to other electrical components (also referred to as “electrical loads”), such as vehicle electronics (e.g., via an auxiliary power module or APM 42), heaters, cooling systems, etc. The battery system 40 may be configured as a rechargeable energy storage system (RESS).

[0046] In one embodiment, the battery system 40 includes a plurality of individual battery components, each of which can be charged independently and can be used to independently power one or more drive systems. For example, the battery system 40 includes a first battery component, such as a first battery pack 44 connected to a front inverter 24, and a second battery pack 46. The first battery pack 44 includes a first plurality of battery modules 48, and the second battery pack 46 includes a second plurality of battery modules 50. Each of the first plurality of battery modules 48 and the second plurality of battery modules 50 includes a plurality of individual battery cells (not shown).

[0047] Each of the front motor 22, the left rear motor 32L, and the right rear motor 32R is a three-phase motor with three-phase motor windings. However, the embodiments described herein are not limited thereto. For example, the motors can be any multi-phase machine powered by a multi-phase inverter, and the drive unit can be implemented using a single machine with independent winding sets.

[0048] The battery system 40 and / or propulsion system 16 include a switching system having various switching devices for controlling the operation of the first battery pack 44 and the second battery pack 46, and selectively connecting the first battery pack 44 and the second battery pack 46 to the front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R. The switching devices can also be operated to selectively connect the first battery pack 44 and the second battery pack 46 to a charging system. The charging system can be used to charge the first battery pack 44 and the second battery pack 46, and / or supply power from the first battery pack 44 and / or the second battery pack 46 to charge another energy storage system (e.g., vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X) charging). The charging system includes one or more charging modules. For example, a first on-board charging module (OBCM) 52 is electrically connected to a charging port 54 for charging and receiving AC systems or devices, such as public AC power. A second OBCM 53 may be included for DC charging (e.g., DC fast charging or DCFC). However, in various embodiments, DC fast charging does not require an OBCM.

[0049] The first OBCM 52 and / or the second OBCM 53 can be connected to the charging station 70 via wire 72 for charging the vehicle 10.

[0050] In this embodiment, the switching system includes a first switching device 60 and a second switching device 62. The first switching device 60 selectively connects the first battery pack 44 to the front inverter 24, the left rear inverter 34L, and the right rear inverter 34R. The second switching device 62 selectively connects the second battery pack 46 to the front inverter 24, the left rear inverter 34L, and the right rear inverter 34R. The switching system also includes a third switching device 64 (also referred to as a "battery pack switching device") for selectively connecting the first battery pack 44 in series to the second battery pack 46.

[0051] Any of a variety of controllers can be used to control the functions of the battery system 40, the switching system, and the drive unit. The controller includes any suitable processing device or unit, and existing controllers such as drive system controllers, RESS controllers, and / or controllers within the drive system can be used. For example, controller 65 may be included for controlling the switching and drive control operations as discussed herein.

[0052] Controller 65 may include processing circuitry, which may include application-specific integrated circuits (ASICs), electronic circuitry, a processor (shared, dedicated, or grouped) and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components providing the described functionality. Controller 65 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of controller 65, implement a method for performing pulse charging of a vehicle's battery using a device employing the vehicle's electrical system according to one or more embodiments detailed herein.

[0053] Vehicle 10 also includes a computer system 55, which includes one or more processing units 56 and a user interface 58. The computer system 55 can communicate with the charging system controller, for example, to provide commands to it in response to user input. Various processing devices, modules, and units can communicate with each other via communication devices or systems such as Controller Area Network (CAN) or Transmission Control Protocol (TCP) buses.

[0054] Figure 2 An illustrative embodiment is shown. Figure 1The vehicle 10 has an electrical system 200. The electrical system 200 includes a direct current (DC) power source (such as a battery 202), an inverter 204 that converts DC power from the battery 202 into AC power, and a motor 206 that operates using the AC power. The motor 206 is typically a three-phase motor. The inverter 204 includes at least three branches (a first branch 208a, a second branch 208b, and a third branch 208c) that are approximately 120 degrees out of phase with each other. Each branch includes a pair of switches that control the conversion of DC power to AC power along the branch. The first branch 208a includes switches Q1 and Q2. The second branch 208b includes switches Q3 and Q4. The third branch 208c includes switches Q5 and Q6. In an embodiment, the switches include transistors with diodes that span from the source to the drain of the transistor. A gate voltage can be applied at the gate of the transistor to control the current flow through the transistor. The transistor can be an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or any other suitable transistor.

[0055] Battery 202 is connected to the inverter via positive bus 210 and negative bus 212.

[0056] Figure 3 A circuit 300 illustrating the charging operation of a vehicle is shown in an embodiment. The circuit 300 includes a charging station 70 and an electrical system 200. A battery 202 and an inverter 204 of the electrical system 200 are shown.

[0057] The first contactor S1 controls the connection between the battery 202 and the inverter 204 along the positive bus 210. The second contactor S2 controls the connection between the positive bus line 210 and the midpoint of the first branch 208a along the line between switches Q1 and Q2. The third contactor S3 and the fourth contactor S4 control the electrical connection between the battery 202 and the inverter along the positive bus 210 during the pre-charge sequence of the charging operation. The controller 65 can be used to control the operation of the first contactor S1, the second contactor S2, the third contactor S3, and the fourth contactor S4.

[0058] Charging station 70 includes a positive DC fast charging port (positive DCFC port 302) and a negative DC fast charging port (negative DCFC port 304). A positive bus charging contactor S5 controls the connection between the positive bus 210 and the positive DCFC port 302, and a negative bus charging contactor S6 controls the connection between the negative bus 212 and the negative DCFC port 304. A first diode D1 is disposed on the positive bus 210. A second diode D2 is disposed on the negative bus 212. The directions of the first diode D1 and the second diode D2 are selected to prevent current from flowing backward from the vehicle into the charging station 70.

[0059] The charging station charges the vehicle in two phases: a constant current phase and a constant voltage phase following the constant current phase. During the constant current phase, a DCFC baseline charging current is supplied to the battery 202. First contactor S1 and second contactor S2 can be controlled to generate a ripple current in the baseline charging current. The ripple current is superimposed on the baseline charging current to form a combined charging current. This combined charging current is used to charge the battery and reduce the time required for charging operations (increasing the charging rate). The ripple current is generated by controlling first contactor S1 and second contactor S2, as well as switches Q1 and Q2. The ripple current can be a sinusoidal current.

[0060] Since the first contactor S1, the second contactor S2, the first diode D1, and the second diode D2 are part of the electrical system, no additional circuitry is needed to generate ripple current. Specifically, the first contactor S1 and the second contactor S2 are part of the inverter 204.

[0061] Figure 4 A graph 400 illustrates the relationship between current and time during charging operation. Time is shown in seconds (s) on the horizontal axis and current in amperes (A) on the vertical axis. Graph 400 shows the baseline charging current 402 and ripple current curve 404. The RMS pulse charging current 406 represents the root mean square current of the combined charging current. Due to relaxed lithium-ion plating limitations, the RMS pulse charging current 406 is greater than the baseline charging current 402. Therefore, the RMS pulse charging current 406 allows for faster battery charging compared to the charging rate using the baseline charging current 402.

[0062] Figure 5 This is a graph 500 showing the relationship between charging current and state of charge for different charging operations. Time (t) is shown on the horizontal axis, and RMS current (A) is shown on the vertical axis. The first curve 502 represents the current during standard DCFC charging using the baseline charging current (without added ripple current), and the second curve 504 represents the current during DCFC pulse charging (ripple current superimposed on the baseline charging current). The first curve 502 shows the baseline constant current phase 506 (at the first power), followed by the baseline constant voltage phase 508. The baseline constant current phase 506 continues until the first phase transition time 510 (at t1), after which the baseline constant voltage phase 508 is used to charge the battery 202.

[0063] The second curve 504 shows a pulsed constant current phase 512 (at the second power), followed by a pulsed constant voltage phase 514. The pulsed constant current phase 512 continues until the second phase transition time 516(t2), after which the pulsed constant voltage phase 514 occurs. The second phase transition time 516 occurs later than the first phase transition time 510 because the ripple current applied in the pulsed constant current phase 512 is more efficient during charging than in the baseline constant current phase 506. Furthermore, the pulsed RMS current during the pulsed constant current phase 512 is greater than the baseline current during the baseline constant current phase 506. For each charging operation, the charging current decays during the pulsed constant voltage phase. The decay of the charging current in the pulsed constant voltage phase 514 is less than the decay of the charging current during the baseline constant voltage phase 508. This difference is due to the fact that the second phase time 516 occurs later than the first phase time 510. Therefore, the duration of the pulsed constant voltage phase 514 is shorter than the duration of the baseline constant voltage phase 508. Therefore, the decay time in the pulse constant voltage phase 514 is less than that in the baseline constant voltage phase 508.

[0064] Figure 6 Figure 600 shows an electrical system with multiple inverters and motors. For illustrative purposes, the electrical system includes a first inverter 602, a first motor 604, a second inverter 606, and a second motor 608. A battery 202 is connected to both the first inverter 602 and the second inverter 606. The phase pin of each inverter can be controlled to generate an AC heating current through the battery without generating any unwanted torque interference in the motors. A single diode D3 is used to prevent current from flowing back from the electrical system to the charging station.

[0065] Figure 7 A graph 700 showing the charging power over time is provided. Time is shown in seconds (s) on the horizontal axis and module power in kilowatts (kW) on the vertical axis. It should be understood that the numerical labels provided along each axis are for illustrative purposes only and do not imply limitation of the methods disclosed herein. Graph 700 includes a first power curve 702 indicating baseline charging operation, a second power curve 704 indicating pulse charging operation (with ripple current), and a third power curve 706 indicating pulse charging with power increased to 1.1 times the maximum power of baseline charging. As shown in the first power curve 702, the baseline charging power is approximately 220 kW during the constant current phase (from approximately t = 0 to approximately t = 1050 seconds). During the constant voltage phase (after approximately t = 1050 seconds), the charging power decreases until the battery 202 is fully charged (at approximately t = 1880 seconds).

[0066] As shown in the second power curve 704, the pulse charging power is approximately 220 kW during the constant current phase (from approximately t = 0 seconds to approximately t = 1250 seconds). During the constant voltage phase (after approximately t = 1250 seconds), the pulse charging power decreases until the battery 202 is fully charged (at approximately t = 1400 seconds).

[0067] As shown in the third power curve 706, the pulse charging with increased power is approximately 220 kW during the constant current phase (from approximately t = 0 seconds to approximately t = 1150 seconds). During the constant voltage phase (after approximately t = 1150 seconds), the pulse charging power with increased power decreases until the battery 202 is fully charged (at approximately t = 1290 seconds).

[0068] Figure 8 A graph 800 shows the state of charge (SOC) as a function of time. Time is shown in seconds (s) on the horizontal axis, and SOC is shown as a percentage of maximum SOC (SOC%) on the vertical axis. Graph 800 includes a first SOC curve 802 indicating baseline charging operation, a second SOC curve 804 indicating pulse charging operation, and a third SOC curve 806 indicating pulse charging with power increased to 1.1 times the maximum power of baseline charging. The first SOC curve 802 reaches 100% charge at approximately t = 1880 seconds. The second SOC curve 804 reaches 100% charge at approximately t = 1400 seconds. The third SOC curve 806 reaches 100% charge at approximately t = 1290 seconds.

[0069] Pulse charging can be used to heat batteries, especially when temperatures change at low temperatures. When the battery temperature is low, the magnitude of the ripple current can be set to prioritize the heating of the battery. This heating effect can be combined with existing on-board battery heaters to increase the heating rate through both the on-board battery heater and the ripple current itself.

[0070] Figure 9 This is a graph 900 showing the low-amplitude ripple current 902 that can be used for charging. Time (t) is shown on the horizontal axis, and current (A) is shown on the vertical axis. The low-amplitude ripple current 902 remains close to the root mean square (RMS) of the charging current. Therefore, the charging current is always positive. The low-amplitude ripple current 902 is ideal for use in the later part of the charging operation and in the constant voltage phase.

[0071] Figure 10This is a graph 1000 showing the medium-range amplitude ripple current 1002 that can be used for charging. Time (t) is shown on the horizontal axis, and current (A) is shown on the vertical axis. The peak-to-peak voltage of the medium-range amplitude ripple current 1002 causes the charging current to drop to zero once per cycle. Therefore, the medium-range amplitude ripple current 1002 suppresses plating at the lithium-ion battery while providing heating to the battery. The medium-range amplitude ripple current 1002 is ideal for the early stages of charging (CC).

[0072] Figure 11 This is a graph 1100 showing the high-amplitude ripple current 1102 that can be used for charging. Time (t) is shown on the horizontal axis, and current (A) is shown on the vertical axis. The peak-to-peak voltage of the high-amplitude ripple current 1102 causes the charging current to drop below zero once per cycle. Therefore, the high-amplitude ripple current 1102 strongly suppresses plating at the lithium-ion battery while providing a high level of heating at the battery. The high-amplitude ripple current 1102 is ideal for the early stages of charging (CC) and low-temperature conditions.

[0073] Figure 12 Figure 1200 illustrates the heating and pulse charging strategy. The first curve 1202 shows the charging rate of the charging operation. The second curve 1204 shows the pulse rate of the charging operation. The third curve 1206 shows the battery temperature. The strategy comprises three stages. In the first stage 1208, the primary objective is to raise the battery temperature as quickly as possible. In the second stage 1210, the objective is to accelerate the charging speed. In the third stage 1212, the objective is to pulse charge until the battery is fully charged.

[0074] In the first stage 1208, there is a low charging rate (first curve 1202) and a high pulse rate (second curve 1204). The battery temperature (third curve 1206) is low. In the second stage 1210, the charging rate (first curve 1202) increases while the pulse rate (second curve 1204) decreases, thereby heating the battery, as shown in the third curve 1206. In the third stage 1212, the charging rate (first curve 1202) decreases. The pulse rate (second curve 1204) is maintained while the battery cell temperature (third curve 1206) increases until the battery is fully charged.

[0075] Figure 13This is graph 1300 showing the charging power of various charging methods for cold batteries. Time is shown in seconds (s) on the horizontal axis and module power in kilowatts (kW) on the vertical axis. For illustrative purposes, the battery temperature starts from -20 degrees Celsius. Time is shown in seconds (s) on the horizontal axis and module power in kilowatts (kW) on the horizontal axis. The first curve 1302 shows the power of baseline charging operation. The second curve 1304 shows the power of baseline charging with external heating (such as from an external heat source) at 0.5 degrees Celsius / minute. The third curve 1306 shows the power for pulse charging without external heating. The fourth curve 1308 shows the power of pulse charging with external heating at 0.5 degrees Celsius / minute. The fifth curve 1310 shows the power of pulse charging with external heating at 0.5 degrees Celsius / minute and 1.1 times the power of baseline charging operation.

[0076] The duration of the charging operation varies between charging operations. The baseline charging operation (first curve 1302) completes at approximately 3400 seconds. The baseline charging operation with external heating at 0.5 degrees / minute (second curve 1304) completes at approximately 2400 seconds. The pulse charging operation without external heating (third curve 1306) completes at approximately 1900 seconds. The pulse charging operation with external heating at 0.5 degrees / minute (fourth curve 1308) completes at approximately 1735 seconds. The pulse charging operation with external heating at 0.5 degrees / minute and 1.1 times the power of the baseline charging operation (fifth curve 1310) completes at approximately 1600 seconds.

[0077] Figure 14 This is graph 1400 showing battery temperatures for various charging methods used for cold batteries. Time is shown in seconds (s) along the horizontal axis, and temperature is shown in degrees Celsius (degC) along the horizontal axis. The first curve 1402 shows the battery temperature during baseline charging. The second curve 1404 shows the battery temperature during baseline charging with external heating at 0.5 degrees / minute. The third curve 1406 shows the battery temperature during ripple charging without external heating. The fourth curve 1408 shows the battery temperature during ripple charging with external heating at 0.5 degrees / minute. The fifth curve 1410 shows the battery temperature during ripple charging with external heating at 0.5 degrees / minute and 1.1 times the power of baseline charging.

[0078] During baseline charging (first curve 1402), the battery temperature rises only slightly to about -15 degrees Celsius. During baseline charging with external heating at 0.5 degrees Celsius / minute (second curve 1404), the battery temperature rises to about 10 degrees Celsius. During ripple charging without external heating (third curve 1406), the battery temperature rises to about 18 degrees Celsius. During ripple charging with external heating at 0.5 degrees Celsius / minute (fourth curve 1408), the battery temperature rises to about 25 degrees Celsius. During ripple charging with external heating at 0.5 degrees Celsius / minute and 1.1 times the power of baseline charging (fifth curve 1410), the battery temperature reaches about 23 degrees Celsius.

[0079] The terms “a” and “an” do not indicate a limitation of quantity, but rather that at least one of the referenced items is present. Unless the context clearly indicates otherwise, the term “or” means “and / or”. Throughout the specification, reference to “aspect” means that a particular element described in connection with that aspect (e.g., a feature, structure, step, or characteristic) is included in at least one aspect described herein and may or may not be present in other aspects. Furthermore, it should be understood that the described elements may be combined in any suitable manner in the aspects.

[0080] When an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it can be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being “directly” on another element, there are no intermediate elements present.

[0081] Unless otherwise stated herein, all test standards are the most recent standards effective up to the filing date of this application, or, if priority is claimed, the most recent standards effective up to the filing date of the earliest priority application in which the test standards appear.

[0082] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0083] While the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from its scope. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the basic scope of this disclosure. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A method for charging a vehicle battery, comprising: The vehicle receives a baseline charging current from a charging station connected to its electrical system, which includes the battery, an inverter, and a positive bus connecting the battery to the inverter and the charging station, wherein the inverter includes a first contactor for connecting the battery and the inverter along the positive bus. Control the first contactor to generate ripple current on the positive bus line; The ripple current is superimposed on the baseline charging current to obtain the combined charging current; and The battery is charged using the combined charging current.

2. The method according to claim 1, wherein, The charging operation includes a constant current phase, and also includes charging the battery using the combined charging current during the constant current phase.

3. The method according to claim 1, wherein, The electrical system includes a second contactor between the midpoint of the positive bus and the branch of the inverter, and the method further includes controlling the first contactor and the second contactor to generate the ripple current.

4. The method of claim 1, further comprising controlling the amplitude of the ripple current to perform at least one of the following: (i) suppressing electroplating at the battery; and (ii) heating the battery.

5. The method according to claim 1, further comprising: The baseline current is provided at a first power, the ripple current is superimposed on the baseline current to generate the combined charging current of the first power, and the combined charging current is increased from the first power to a second power greater than the first power.

6. An electrical system for a vehicle, comprising: Battery; An inverter connected to the battery via a positive bus; The first contactor within the inverter connects the battery to the inverter via the positive bus; A charging port is used to connect the positive bus to a charging station to receive a baseline charging current from the charging station; and A processor configured to control the first contactor to generate a ripple current in the positive bus, wherein the ripple current is superimposed on the baseline charging current to obtain a combined charging current for charging the battery.

7. The electrical system of claim 6, wherein the charging operation includes a constant current phase, and the processor is further configured to charge the battery using the combined charging current during the constant current phase.

8. The electrical system according to claim 6, wherein, The electrical system includes a second contactor between the midpoint of the positive bus and the branch of the inverter, and the processor is further configured to control the first and second contactors to generate the ripple current.

9. The electrical system of claim 6, wherein the processor is further configured to control the amplitude of the ripple current to perform at least one of the following: (i) suppressing electroplating at the battery; and (ii) heating the battery.

10. The electrical system of claim 6, wherein the processor is further configured to provide the baseline current at a first power, superimpose the ripple current on the baseline current to generate the combined charging current at the first power, and increase the combined charging current from the first power to a second power greater than the first power.

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