Multi-level multifunctional inverter

Abstract

A vehicle includes a system for charging a battery of the vehicle. The motor is coupled to the charging station. A T-bridge multilevel inverter couples the motor to the battery. The inverter includes a first branch having a first set of switches and a first AC terminal coupled to the motor, a second branch having a second set of switches and a second AC terminal coupled to the motor, and a third branch having a third set of switches and a third AC terminal coupled to the motor. The processor connects the third AC terminal to the charging station and controls the first set of switches to control a first current through the first AC terminal of the first leg and / or controls the second set of switches to control a second current through the second AC terminal of the second leg.

Description

Technical Field

[0001] The present disclosure relates to charging a battery of an electric vehicle, and in particular, to a method of operating switches of a multi-level inverter to control a charging operation. Background Art

[0002] Electric vehicles are being produced with battery capacities that exceed the charging capacity of currently available charging stations. To support backward compatibility of these electric vehicles, many electric vehicles have been equipped with additional on-board electronics in the form of direct current (DC-DC) converters. However, such additional on-board electronics are undesirable because they increase the cost of the vehicle as well as its mass and volume. Therefore, it is desirable to provide a method of charging a vehicle at currently available charging stations without requiring additional on-board electronics to provide backward compatibility. Summary of the invention

[0003] In one exemplary embodiment, a method for charging a battery of an electric vehicle is disclosed. A charging station is coupled to a motor of the vehicle, wherein the motor is coupled to the battery via a T-bridge multilevel inverter, the T-bridge multilevel inverter comprising a first branch having a first set of switches and a first AC terminal coupled to the motor, a second branch having a second set of switches and a second AC terminal coupled to the motor, and a third branch having a third set of switches and a third AC terminal coupled to the motor. The third AC terminal of the third branch is connected to the charging station. The first set of switches is controlled to control a first current through the first AC terminal of the first branch, and / or the second set of switches is controlled to control a second current through the second AC terminal of the second branch, to charge the battery through the motor via the charging station.

[0004] In addition to one or more features described herein, controlling the first current further comprises controlling a first switching period of a first set of switches of the first branch, and controlling the second current further comprises controlling a second switching period of a second set of switches of the second branch.

[0005] In addition to one or more features described herein, the first branch includes a switch pair, and the switches of the switch pair receive inputs that are 180 degrees out of phase.

[0006] In addition to one or more features described herein, the method also includes controlling a first magnitude of the first current and a second magnitude of the second current to generate a net zero torque at the motor for any angular position of a rotor of the motor.

[0007] In addition to one or more features described herein, the battery includes a first battery half group and a second battery half group, and the method further includes opening a switch of the third branch to isolate one of the first battery half group and the second battery half group for separate charging.

[0008] In addition to one or more features described herein, the third branch includes a first pair of switches connected in series between a positive DC voltage bus and a negative DC voltage bus and a second pair of switches connected in series between a third AC terminal and a neutral point, and the method further includes one of: executing placing all switches of the third branch in a closed configuration, and closing the first pair of switches and opening the second pair of switches.

[0009] In addition to one or more features described herein, the method also includes connecting the second branch and the third branch to the charging station using a switch, the switch being operated to multiplex the connection of the second branch and the third branch to the charging station.

[0010] In another exemplary embodiment, a system for charging a battery of a vehicle is disclosed. The system includes an electric motor, a T-bridge multilevel inverter, and a processor. The electric motor may be coupled to a charging station. The T-bridge multilevel inverter includes a first branch having a first set of switches and a first AC terminal coupled to the electric motor, a second branch having a second set of switches and a second AC terminal coupled to the electric motor, and a third branch having a third set of switches and a third AC terminal coupled to the electric motor, wherein the T-bridge multilevel inverter is configured to couple the electric motor to the battery. The processor is configured to connect the third AC terminal of the third branch to the charging station, and to control the first set of switches to control a first current through the first AC terminal of the first branch, and / or to control the second set of switches to control a second current through the second AC terminal of the second branch, so as to charge the battery through the electric motor via the charging station.

[0011] In addition to one or more features described herein, the processor is further configured to control the first current by controlling a first switching period of the first set of switches of the first branch, and control the second current by controlling a second switching period of the first set of switches of the second branch.

[0012] In addition to one or more features described herein, the first branch includes a switch pair, and the processor is further configured to provide a carrier signal to the switch pair, wherein switches in the switch pair receive inputs that are 180 degrees out of phase.

[0013] In addition to one or more features described herein, the processor is further configured to control a first magnitude of the first current and a second magnitude of the second current to generate a net zero torque at the electric motor for any angular position of a rotor of the motor.

[0014] In addition to one or more features described herein, the battery includes a first battery half group and a second battery half group, and the processor is further configured to open the switch of the third branch to isolate one of the first battery half group and the second battery half group for separate charging.

[0015] In addition to one or more features described herein, the third branch includes a first pair of switches connected in series between the positive DC voltage bus and the negative DC voltage bus and a second pair of switches connected in series between the third AC terminal and the neutral point, and the processor is further configured to perform one of the following: (i) placing all switches of the third branch in a closed configuration; and (ii) closing the first pair of switches and opening the second pair of switches.

[0016] In addition to one or more features described herein, the processor is further configured to control a first connection between the second branch and the charging station and a second connection between the third branch and the charging station to multiplex operations of the first connection and the second connection.

[0017] In yet another exemplary embodiment, a vehicle is disclosed. The vehicle includes a battery, an electric motor, a T-bridge multilevel inverter, and a processor. The electric motor may be coupled to a charging station. The T-bridge multilevel inverter includes a first branch having a first set of switches and a first AC terminal coupled to the electric motor, a second branch having a second set of switches and a second AC terminal coupled to the electric motor, and a third branch having a third set of switches and a third AC terminal coupled to the electric motor, wherein the T-bridge multilevel inverter is configured to couple the electric motor to the battery. The processor is configured to connect the third AC terminal of the third branch to the charging station, and to control the first set of switches to control a first current through the first AC terminal of the first branch, and / or to control the second set of switches to control a second current through the second AC terminal of the second branch, so as to charge the battery through the electric motor via the charging station.

[0018] In addition to one or more features described herein, the processor is configured to control the first current by controlling a first switching period of a first set of switches of the first branch, and to control the second current by controlling a second switching period of a second set of switches of the second branch.

[0019] In addition to one or more features described herein, the first branch includes a switch pair, and the processor is further configured to provide a carrier signal to the switch pair, wherein switches in the switch pair receive complementary inputs.

[0020] In addition to one or more features described herein, the processor is further configured to control a first magnitude of the first current and a second magnitude of the second current to generate a net zero torque at the electric motor for any angular position of a rotor of the motor.

[0021] In addition to one or more features described herein, the battery includes a first battery half group and a second battery half group, and the processor is further configured to open the switch of the third branch to isolate one of the first battery half group and the second battery half group for separate charging.

[0022] In addition to one or more features described herein, the third branch includes a first pair of switches connected in series between the positive DC voltage bus and the negative DC voltage bus and a second pair of switches connected in series between the third AC terminal and the neutral point, and the processor is further configured to perform one of the following: (i) placing all switches of the third branch in a closed configuration; and (ii) closing the first pair of switches and opening the second pair of switches.

[0023] The above features and advantages and other features and advantages of the present disclosure are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, advantages and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0025] Figure 1 A vehicle according to an exemplary embodiment is shown;

[0026] Figure 2 A charging circuit for charging an electric vehicle in an embodiment is shown;

[0027] Figure 3 is a schematic diagram showing details of the motor and inverter;

[0028] Figure 4 is a schematic diagram showing a motor, an inverter and an inverter control circuit;

[0029] Figure 5 is a schematic diagram showing details for charging a selected battery in an embodiment;

[0030] Figure 6 shows a phase diagram of a motor in an embodiment;

[0031] Figure 7 A phase diagram of a motor in another embodiment is shown;

[0032] Figure 8 A phase diagram of a motor in another embodiment is shown;

[0033] Fig. 9 is a diagram showing an inverter in a configuration for charging a single battery half pack; and

[0034] Fig.10An inverter in another embodiment is shown. DETAILED DESCRIPTION

[0035] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features.

[0036] According to an exemplary embodiment, Figure 1 A vehicle 10 is shown including a body 12 that at least partially defines an occupant compartment 14. The body 12 also supports various vehicle subsystems, including a propulsion system 16, and other subsystems such as braking subsystems, suspension systems, steering subsystems, etc., for supporting the functions of the propulsion system 16 and other vehicle components.

[0037] The vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or any other vehicle. In an embodiment, the vehicle 10 is an electric vehicle including a plurality of motors and / or a drive system. 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 the vehicle 10 in various operating modes, such as a normal mode, a high-performance mode (in which additional torque is applied), an all-wheel drive ("AWD"), a front-wheel drive ("FWD"), a rear-wheel drive ("RWD"), etc.

[0038] For example, the propulsion system 16 is a multi-drive system that includes 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 motor 32L and an inverter 34L. The right rear drive unit 30R includes a motor 32R and an inverter 34R. Inverters 24, 34L and 34R (e.g., power inverter units or PIMs) each convert DC power from a high voltage (HV) battery system 40 into multi-phase (e.g., two-phase, three-phase, six-phase, etc.) alternating current (AC) power to drive the front motor 22 and the rear motors 32L and 32R.

[0039] like Figure 1 As shown, the drive system features a single motor. However, embodiments are not limited thereto. For example, instead of a single motor, multiple drives may be provided by a single machine having physically separate sets of windings.

[0040] Also like Figure 1As shown, the drive system is configured such that the front motor 22 drives the front wheels (not shown), and the rear motors 32L and 32R drive the rear wheels (not shown). However, the embodiments are not limited in this regard, as there may be any number of drive systems and / or motors at various locations (e.g., a motor driving each wheel, dual motors per axle, etc.). In addition, the embodiments are not limited to dual drive systems, as the embodiments may be used with vehicles having any number of motors and / or power inverters.

[0041] 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 a 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).

[0042] In one embodiment, the battery system 40 includes a plurality of individual battery assemblies, each of which can be independently charged and can be used to independently power one or more drive systems. For example, the battery system 40 includes a first battery assembly, such as a first battery subgroup 44 connected to the front inverter 24, and a second battery subgroup 46. The first battery subgroup 44 includes a plurality of battery modules 48, and the second battery subgroup 46 includes a plurality of battery modules 50. Each battery module 48, 50 includes a plurality of independent battery cells (not shown). In various embodiments, one or more of the battery packs may include MODACS (Multi-Output Dynamically Adjustable Capacity) batteries, as described herein with respect to Figure 2-4 described.

[0043] Each of the front motor 22 and the rear motors 32L and 32R is a three-phase motor having a three-phase motor winding. However, the embodiments described herein are not limited thereto. For example, the motor may be any multi-phase machine supplied by a multi-phase inverter, and the drive unit may be implemented using a single machine having an independent winding set.

[0044] The battery system 40 and / or the propulsion system 16 include a switching system having various switching devices for controlling the operation of the battery packs 44 and 46 and selectively connecting the battery packs 44 and 46 to the front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R. The switching device can also be operated to selectively connect the first battery subgroup 44 and the second battery subgroup 46 to the charging system. The charging system can be used to charge the first battery subgroup 44 and the second battery subgroup 46, and / or supply power from the first battery subgroup 44 and / or the second battery subgroup 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 onboard charging module (OBCM) 52 is electrically connected to a charging port 54 for charging to and from an AC system or device (such as a utility AC power source). A second OBCM 53 may be included for DC charging (e.g., DC fast charging or DCFC). As Figure 1 As shown, the utility AC power source is a charging station 110 connected to the charging port 54 via an electrical line 112 .

[0045] In an embodiment, the switching system includes a first switching device 60 that selectively connects the first battery subgroup 44 to the inverters 24, 34L, and 34R, and a second switching device 62 that selectively connects the second battery subgroup 46 to the inverters 24, 34L, and 34R. The switching system also includes a third switching device 64 (also referred to as a "battery switching device") for selectively connecting the first battery subgroup 44 to the second battery subgroup 46 in series.

[0046] Any of a variety of controllers may 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 an existing controller may be used, such as a drive system controller, a RESS controller, and / or a controller in the drive system. For example, a controller 65 may be included to control the switching and drive control operations as discussed herein.

[0047] The controller 65 may include processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. The controller 65 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of the controller 65, implement a method of charging the battery according to one or more embodiments detailed herein. This method includes operating various control blocks and switches of the vehicle, as discussed herein.

[0048] Figure 2 A charging circuit 200 for charging an electric vehicle 10 in an embodiment is shown. The charging circuit 200 shows a charging station 202 and a vehicle electronic device 204. The vehicle electronic device 204 includes a battery pack 206 or power supply, an electric motor 208, and an inverter 210, which couples the battery pack to the electric motor and converts the direct current (DC) power from the battery pack into alternating current (AC) power for use at the electric motor. In various embodiments, the battery pack 206 is a single battery pack or multiple battery half packs with a total voltage capacity of +800 volts. The inverter 210 is a T-bridge multi-level inverter that includes a branch for each phase winding of the electric motor 208. In various embodiments, the electric motor 208 is a three-phase motor with a three-phase winding. Therefore, the inverter 210 includes three branches. The vehicle electronic device 204 also includes an accessory load 212, which typically has a +800V power capacity and is directly connected to the battery pack 206.

[0049] The battery pack 206 may be connected to the charging station 202 via a positive DCFC bus 214 and a negative DCFC bus 216. The positive DCFC bus 214 includes a first switch S1 and the negative DCFC bus 216 includes a second switch S2, which are placed in an open configuration to disconnect from the charging station and placed in a closed configuration to connect to the charging station 202. A bypass line 218 is connected from the positive DCFC bus 214 to the phase windings of the motor 208, thereby providing a second channel for charging the battery pack 206. A bypass switch S3 on the bypass line 218 may be placed in a closed position to selectively implement the second channel.

[0050] Figure 3 3 is a schematic diagram 300 showing details of the motor 208 and the inverter 210. The motor 208 includes a rotor having a first phase winding 308 (labeled "A"), a second phase winding 310 (labeled "B"), and a third phase winding 312 (labeled "C"). The motor 208 is connected to the charging station 202 via a charging bus 304. The filter capacitor 306 controls the voltage level at the motor 302 by preventing or reducing spikes in the charging voltage.

[0051] The inverter 210 is connected to the battery pack 206 via a positive DC voltage bus 314 and a negative DC voltage bus 316. The battery pack 206 includes a first battery half pack 206a and a second battery half pack 206b connected in series with a neutral point O between the first battery and the second battery.

[0052] The inverter 210 includes a first branch 318, a second branch 320, and a third branch 322, each branch extending between the positive DC voltage bus 314 and the negative DC voltage bus 316. Each branch includes four switches arranged in a T-shaped configuration. For example, the first branch 318 includes switches X1, X2, X3, and X4. Switches X1 and X2 are connected in series between the positive DC voltage bus 314 and the negative DC voltage bus 316. The first phase winding 308 of the motor 302 is connected to the first AC terminal (labeled "A") between the first switch X1 and the second switch X2 of the first branch 318. Switches X3 and X4 are connected in series between the first AC terminal and the neutral point O of the battery pack 206. Similarly, the second branch 320 includes switches X5, X6, X7, and X8 in a T-shaped configuration. Switches X5 and X6 are connected in series between the positive DC voltage bus 314 and the negative DC voltage bus 316. The second phase winding 310 of the motor 302 is connected to the second AC terminal (labeled as "B") of the second branch 320 between the switch X5 and the switch X6. The switches X7 and X8 are connected in series between the second AC terminal and the neutral point O of the battery pack 206. In addition, the third branch 322 includes switches X9, X10, X11 and X12 in a T-shaped configuration. The switches X9 and X10 are connected in series between the positive DC voltage bus 314 and the negative DC voltage bus 316. The third phase winding 312 of the motor 302 is connected to the third AC terminal (labeled as "C") of the third branch 322 between the switch X9 and the switch X10. The switches X11 and X12 are connected in series between the third AC terminal and the neutral point O of the battery pack 206.

[0053] Figure 4 4 is a schematic diagram 400 showing the motor 208, the inverter 210, and the inverter control circuit 402. The inverter control circuit 402 is used to control the current flow through the branches of the inverter 210 during the charging scenario of the battery pack 206. The inverter control circuit 402 includes a first control block 404 for controlling the switches (X1, X2, X3, X4) of the first branch 318, a second control block 406 for controlling the switches (X5, X6, X7, X8) of the second branch 320, and a third control block 408 for controlling the switches (X9, X10, X11, X12) of the third branch 322.

[0054] The first control block 404 provides control signals to switches (X1, X2, X3, X4) grouped into switch pairs (i.e., a first switch pair [X1, X2] and a second switch pair [X3, X4]). The first switch pair [X1, X2] is driven by complementary control inputs. For example, the logic inverter 410 at switch X1 ensures that switch X1 is disconnected when X2 is turned on, and switch X1 is turned on when X2 is turned off. The second switch pair [X3, X4] operates similarly to the logic inverter 410 at the third switch X3. The first comparator 412 receives the first carrier signal T1 and the duty cycle signal and provides an output that is sent to the first switch pair [X1, X2]. Similarly, the second comparator 414 receives the first carrier signal T1 and the duty cycle signal and provides an output that is sent to the second switch pair [X3, X4]. The first carrier signal is offset 180 degrees in phase from the second carrier signal. This results in switch pairs [X1, X2] and [X3, X4] being 180 degrees out of phase with each other. In other words, switch X1 and switch X3 are 180 degrees out of phase with each other during the switching cycle, and switch X2 and switch X4 are 180 degrees out of phase with each other during the switching cycle.

[0055] The second control block 406 operates similarly to the first control block 404 using a second carrier signal T3 for controlling the switch pairs [X5, X6] and [X7, X8]. The carrier signal T3 and the carrier signal T4 are offset by 180 degrees relative to each other. In addition, the carrier signal T3 is offset by 180 degrees relative to the carrier signal T1. In an embodiment, the duty cycle is a single duty cycle applied across the first control block 404 and the second control block 406. In another embodiment, the first control block 404 can receive a first duty cycle signal, and the second control block 406 can receive a second duty cycle signal.

[0056] In the charging scenario, the third control block turns off the switch (X9, X10, X11, X12) of the third branch 322, and the charging station 110 is connected to the third AC terminal. The first control block 404 and the second control block 406 are used to control the flow of the first current through the first branch 318 and the flow of the second current through the second branch 320, respectively. In another embodiment, the first control block 404 disconnects the switch (X1, X2, X3, X4) of the first branch 318, and the charging station 110 is connected to the first AC terminal. The second control block 406 and the third control block 408 control the current flow through the second branch 320 and the third branch 322, respectively. In yet another embodiment, the second control block 406 turns off the switch (X5, X6, X7, X8) of the second branch 320, and the charging station 110 is connected to the second AC terminal. The first control block 404 and the third control block 408 control the current flow through the first branch 318 and the third branch 322, respectively.

[0057] Figure 55 is a schematic diagram 500 showing details for charging a selected battery (e.g., the first battery half group 206a) in an embodiment. The third control block 408 configures the third branch 322 with switches X9 and X10 in the open position and switches X11 and X12 in the on position. Thus, the charging bus 304 is connected to the neutral point O via switches X11 and X12. Phase winding A 308 is connected to the negative DC voltage bus 316 through the first branch 318 (and switch X2). In this configuration, the charging station 202 is connected only to the first battery half group 206a. A similar switch configuration can be used to connect the charging station only to the second battery half group 206b.

[0058] Figure 6 A phase diagram 600 of the motor 302 in an embodiment is shown. The phase diagram 600 includes a first phase branch A representing the current phase through the first phase winding 308, a second phase branch B representing the current phase through the second phase winding 310, and a third phase C representing the current phase through the third phase winding 312. The phase branches A, B, and C are 120 degrees out of phase with each other. The direct axis 602 (D) and the orthogonal axis 604 (Q) of the rotor of the motor 302 are shown on the phase diagram 600. For illustrative purposes, the direct axis 602 is aligned along the first phase branch A. In order to ensure net zero torque generation or minimum torque generation at the rotor, the current is controlled to generate a net current vector along the D axis. This can be achieved, for example, by connecting a charging station to the first phase winding 308 (aligned with the +D axis) and then controlling the magnitude of the negative current (i.e., the current from the charging station to the battery) through the second phase winding B and the third phase winding C to be equal. The current through the second phase winding B generates a first negative torque vector 606, and the current through the third phase winding C generates a second negative torque vector 608. The magnitude of the first negative torque vector 606 is equal to the magnitude of the second negative torque vector 608. Therefore, the sum of these torque vectors is along the direct axis 602 (i.e., along the first phase leg A).

[0059] Figure 7 A phase diagram 700 of a motor in another embodiment is shown. The direct axis 602 is aligned opposite to the first phase leg A. The current through the second phase winding B is controlled to produce a first positive torque vector 702. The current through the third phase winding C is also controlled to produce a second positive torque vector 704. The sum of these torque vectors is along the direct axis 602 (antiparallel to the first phase leg A).

[0060] Figure 8A phase diagram 800 of a motor in another embodiment is shown. The direct axis 602 of the rotor is not aligned with the phase axis A. The current can be controlled to have different currents in the second phase winding B and the third phase winding C, thereby generating a first torque vector 802 and a second torque vector 804 with different magnitudes. The sum of these torque vectors produces a combined torque along the D axis. Therefore, for any angular position of the D axis of the rotor, the appropriate branches of the inverter can be disconnected, and the current through the remaining branches can be appropriately controlled to provide the desired torque vector along the D axis.

[0061] Fig. 9 900 is a diagram showing an inverter in a configuration for charging a single battery half-stack. The DCFC port is connected to the phase leg via a switch box 902, which includes a first DCFC switch 904, a second DCFC switch 906, and a third DCFC switch 908. The first DCFC switch 904 connects the first branch 318 and the second branch 320 to the third branch 322 across the positive DC voltage bus 314 (i.e., the connection between node H1 and node H2). The second DCFC switch 906 connects the first branch 318 and the second branch 320 to the third branch 322 across the neutral point (i.e., the connection between node M1 and node M2). The third DCFC switch 908 connects the charging bus 304 to the neutral point via the third branch 322. In Fig. 9 In the configuration shown, the first DCFC switch 904 is open (off), the second DCFC switch 906 is open (off), and the third DCFC switch 908 is closed (on). In addition, the third branch 322 includes switches X9 and X10 placed in a closed (off) configuration and switches X11 and X12 placed in an open (on) configuration. In this configuration, the C2 capacitor can be used as a +400V input DC capacitor (i.e., a filter capacitor for charging).

[0062] Fig.10 An inverter 1000 in another embodiment is shown. The charging bus 304 includes a first charging line 1002 connected to the second phase winding 310 and a second charging line 1004 connected to the third phase winding 312. The first charging line 1002 includes a first charging line switch 1006, and the second charging line 1004 includes a second charging line switch 1008. The first charging line switch 1006 and the second charging line switch 1008 can be operated to provide multiplexed input phases to minimize stress on the motor during the charging process.

[0063] The terms "one" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. Unless the context clearly indicates otherwise, the term "or" means "and / or." References to "aspects" throughout the specification mean that a particular element (e.g., a feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in the various aspects.

[0064] 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 intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0065] Unless otherwise indicated herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the test standards appear.

[0066] Unless defined otherwise, 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 belongs.

[0067] Although the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be substituted with equivalents without departing from the scope thereof. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the disclosure without departing from the basic scope of the disclosure. Therefore, it is intended that the disclosure is not limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A method for charging a battery of an electric vehicle, comprising: coupling a charging station to an electric motor of the vehicle, wherein the electric motor is coupled to the battery via a T-bridge multilevel inverter, the T-bridge multilevel inverter comprising a first branch having a first set of switches and a first AC terminal coupled to the electric motor, a second branch having a second set of switches and a second AC terminal coupled to the electric motor, and a third branch having a third set of switches and a third AC terminal coupled to the electric motor; connecting a third AC terminal of the third branch to the charging station; and The first set of switches is controlled to control a first current through a first AC terminal of the first branch and / or the second set of switches is controlled to control a second current through the second AC terminal of the second branch to charge the battery through the electric motor via the charging station.

2. The method according to claim 1, wherein: Controlling the first current further includes controlling a first switching period of a first set of switches of the first branch, and controlling the second current further includes controlling a second switching period of a second set of switches of the second branch.

3. The method according to claim 1, wherein: The battery includes a first battery half group and a second battery half group, and the method further includes opening a switch of the third branch to isolate one of the first battery half group and the second battery half group for separate charging.

4. The method according to claim 1, wherein: The third branch includes a first pair of switches connected in series between a positive DC voltage bus and a negative DC voltage bus and a second pair of switches connected in series between the third AC terminal and a neutral point, and the method further includes performing one of the following: (i) placing all switches of the third branch in a closed configuration; and (ii) closing the first pair of switches and opening the second pair of switches.

5. The method of claim 1, further comprising connecting the second branch and the third branch to the charging station using a switch, the switch being operated to multiplex the connection of the second branch and the third branch to the charging station.

6. A system for charging a battery of a vehicle, comprising: an electric motor, the electric motor being connectable to a charging station; a T-bridge multilevel inverter, the T-bridge multilevel inverter comprising a first branch having a first set of switches and a first AC terminal coupled to the motor, a second branch having a second set of switches and a second AC terminal coupled to the motor, and a third branch having a third set of switches and a third AC terminal coupled to the motor, wherein the T-bridge multilevel inverter is configured to couple the motor to the battery; The processor is configured as: connecting a third AC terminal of the third branch to the charging station; and The first set of switches is controlled to control a first current through a first AC terminal of the first branch and / or the second set of switches is controlled to control a second current through a second AC terminal of the second branch to charge the battery through the electric motor via the charging station.

7. The system according to claim 6, wherein: The processor is further configured to control the first current by controlling a first switching period of a first set of switches of the first branch, and to control the second current by controlling a second switching period of a first set of switches of the second branch.

8. The system according to claim 6, wherein: The battery includes a first battery half group and a second battery half group, and the processor is further configured to open a switch of the third branch to isolate one of the first battery half group and the second battery half group for separate charging.

9. The system according to claim 6, wherein: The third branch includes a first pair of switches connected in series between a positive DC voltage bus and a negative DC voltage bus and a second pair of switches connected in series between the third AC terminal and a neutral point, and the processor is further configured to perform one of the following: (i) placing all switches of the third branch in a closed configuration; and (ii) closing the first pair of switches and opening the second pair of switches.

10. The system according to claim 6, wherein: The processor is further configured to control a first connection between the second branch and the charging station and a second connection between the third branch and the charging station to multiplex operations of the first connection and the second connection.

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