Multi-stage multi-function inverter

Abstract

A vehicle includes a system for charging its battery. An electric motor is connected to a charging station. A T-bridge multi-stage inverter connects the electric motor to the battery. The inverter includes a first branch with a first set of switches and a first AC terminal connected to the electric motor, a second branch with a second set of switches and a second AC terminal connected to the electric motor, and a third branch with a third set of switches and a third AC terminal connected to the electric motor. A 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 branch and / or the second set of switches to control a second current through the second AC terminal of the second branch.

Description

INTRODUCTION

[0001] The present disclosure relates to charging a battery of an electric vehicle and, more particularly, to a method for operating switches of a multi-level inverter to control charging operation.

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

[0003] According to an exemplary embodiment, a method for charging a battery of an electric vehicle is disclosed. A charging station is coupled to an electric motor of the vehicle, the electric motor being coupled to the battery through a T-bridge multi-level inverter including a first branch circuit with a first set of switches and a first AC terminal coupled to the electric motor, a second branch circuit with a second set of switches and a second AC terminal coupled to the electric motor, and a third branch circuit with a third set of switches and a third AC terminal coupled to the electric motor. The third AC terminal of the third branch circuit 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 line branch and / or the second set of switches is controlled to control a second current through the second AC terminal of the second line branch in order to charge the battery via the charging station by the electric motor.

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

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

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

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

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

[0009] In addition to one or more of the features described herein, the method further includes connecting the second line leg and the third line leg to the charging station using switches operable to multiplex connections of the second line leg and the third line leg to the charging station.

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

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

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

[0013] In addition to one or more of the 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 produce zero net torque at the electric motor for any angular location of a rotor of the motor.

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

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

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

[0017] According to yet another embodiment, a vehicle is disclosed. The vehicle includes a battery, an electric motor, a T-bridge multi-level inverter, and a processor. The electric motor can be coupled to a charging station. The T-bridge multi-level inverter includes a first line leg having a first set of switches and a first AC terminal coupled to the electric motor, a second line leg having a second set of switches and a second AC terminal coupled to the electric motor, and a third line leg having a third set of switches and a third AC terminal coupled to the electric motor, wherein the T-bridge multi-level inverter is configured to couple the electric motor to the battery.The processor is configured to connect the third AC terminal of the third line 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 line branch and / or the second set of switches to control a second current through a second AC terminal of the second line branch for charging the battery via the charging station by the electric motor.

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

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

[0020] In addition to one or more of the 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 produce zero net torque at the electric motor for any angular location of a rotor of the motor.

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

[0022] In addition to one or more of the features described herein, the third branch circuit includes a first pair of switches in series between a positive DC voltage bus and a negative DC voltage bus and a second pair of switches in series between the third AC terminal and the neutral point, wherein the processor is further configured to perform: (i) placing all switches of the third branch circuit in a closed configuration; or (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 disclosure will be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 a vehicle according to an exemplary embodiment; Fig. 2 a charging circuit for charging the electric vehicle according to an embodiment; Fig. 3 a circuit diagram of details of the electric motor and the inverter; Fig. 4 a circuit diagram of the electric motor, the inverter and an inverter control circuit; Fig. 5 is a circuit diagram illustrating details for charging a selected battery according to one embodiment; Fig. 6 shows a phase diagram of the electric motor according to an embodiment; Fig. 7 shows a phase diagram of the electric motor according to another embodiment; Fig. 8 shows a phase diagram of the electric motor according to another embodiment; Fig. 9 is a circuit diagram of the inverter in a configuration for charging a single battery half-pack; and Fig. 10 the inverter according to another embodiment. DETAILED DESCRIPTION

[0025] 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 corresponding reference characters designate like or corresponding parts and features throughout the drawings.

[0026] Fig. 1 shows a vehicle 10 including a vehicle body 12 that at least partially defines a passenger compartment 14, according to an exemplary embodiment. The vehicle body 12 also supports various vehicle subsystems, including a propulsion system 16 and other subsystems for supporting functions of the propulsion system 16, as well as other vehicle components such as a braking subsystem, a suspension subsystem, a steering subsystem, and others.

[0027] The vehicle 10 may be an electric vehicle (EV), a hybrid vehicle, or any other vehicle. According to one embodiment, the 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 front wheels (not shown) and / or rear wheels (not shown). The drive units are controllable to operate the vehicle 10 in various modes, such as a normal mode, a high-performance mode (in which additional torque is applied), all-wheel drive ("AWD"), front-wheel drive ("FWD"), rear-wheel drive ("RWD"), and others.

[0028] The propulsion system 16 is, for example, a multi-drive system that includes a front drive unit 20 for driving front wheels and rear drive units for driving rear wheels. The front drive unit 20 includes a front electric 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. A left rear drive unit 30L includes an electric motor 32L and an inverter 34L. A right rear drive unit 30R includes an electric motor 32R and an inverter 34R. The inverters 24, 34L, and 34R (e.g., the power inverter units or PIMs) each convert DC power from a high-voltage (HV) battery system 40 into multi-phase AC power (e.g., two-phase AC power, three-phase AC power, six-phase AC power, etc.) to control the front electric motor 22 and the rear electric motors 32L and 32R.

[0029] As in Fig. As shown in Figure 1, the drive systems comprise separate electric motors. However, embodiments are not limited to this. For example, instead of separate motors, multiple drives may be provided by a single machine having multiple sets of physically independent windings.

[0030] As also in Fig. 1, the drive systems are configured such that the front electric motor 22 drives front wheels (not shown) and the rear electric motors 32L and 32R drive rear wheels (not shown). However, since there may be any number of drive systems and / or motors in different locations (e.g., one motor driving each wheel, two motors per axle, etc.), embodiments are not limited thereto. Furthermore, since embodiments may be used with a vehicle having any number of motors and / or power inverters, embodiments are not limited to a dual drive system.

[0031] The front drive unit 20, the left rear drive unit 30L, and the right rear drive unit 30R in the propulsion system 16 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), heating devices, cooling systems, and others. The battery system 40 may be configured as a rechargeable energy storage system (RESS).

[0032] According to one embodiment, the battery system 40 includes a plurality of separate battery assemblies in which each battery assembly can be independently charged and used to independently supply power to a propulsion system or systems. For example, the battery system 40 includes a first battery assembly, such as a first battery sub-pack 44 connected to the front inverter 24, and a second battery sub-pack 46. The first battery sub-pack 44 includes a plurality of battery modules 48, and the second battery sub-pack 46 includes a plurality of battery modules 50. Each battery module 48, 50 includes a number of individual cells (not shown). According to various embodiments, one or more of the battery packs may comprise a MODACS (Multi-Output Dynamically Adjustable Capacity) battery, as described herein with respect to Fig. 2-4 is included.

[0033] Both the front electric motor 22 and the rear electric motors 32L and 32R are three-phase motors with three-phase motor windings. However, the embodiments described herein are not limited to this. For example, the motors can be any multiphase machines powered by multiphase inverters, and the drive units can be implemented using a single machine with independent sets of windings.

[0034] The battery system 40 and the propulsion system 16 include a switching system with various switching devices for controlling the operation of the battery packs 44 and 46 and for selectively connecting the battery packs 44 and 46 to the front propulsion unit 20, to the left rear propulsion unit 30L, and to the right rear propulsion unit 30R. The switching devices are also operable to selectively connect the first battery subpack 44 and the second battery subpack 46 to a charging system. The charging system can be used to charge the first battery subpack 44 and the second battery subpack 46 and / or to supply power from the first battery subpack 44 and / or the second battery subpack 46 to charge another energy storage system (e.g., vehicle-to-vehicle (V2V) charging and / or vehicle-to-all (V2X) charging). The charging system contains 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 to and from an AC system or device, such as a utility AC power supply. A second OBCM 53 may be included for DC charging (e.g., for DC fast charging or DCFC). As shown in FIG. Fig. 1, the utility AC power supply is a charging station 110 connected to the charging port 54 via a cable 112.

[0035] According to one embodiment, the switching system includes a first switching device 60 that selectively connects the first battery subpack 44 to the inverters 24, 34L, and 34R, and a second switching device 62 that selectively connects the second battery subpack 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 subpack 44 to the second battery subpack 46 in series.

[0036] Any number of controllers may be used to control the functions of the battery system 40, the switching system, and the drive units. A controller may include any suitable processing device or processing unit and may utilize an existing controller such as a drive system controller, a RESS controller, and / or a controller within the drive system. For example, a controller 65 may be included for controlling switching and trigger control operations as discussed herein.

[0037] The controller 65 may include processing circuitry, which may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory executing one or more software or firmware programs, combinational logic circuitry, 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 for charging a battery according to one or more embodiments detailed herein. Such a method includes operating various control blocks and switches of the vehicle as discussed herein.

[0038] Fig. 2 shows a charging circuit 200 for charging the electric vehicle 10 according to one embodiment. The charging circuit 200 shows the charging station 202 and vehicle electronics 204. The vehicle electronics 204 includes a battery pack 206 or power source, an electric motor 208, and an inverter 210 that couples the battery pack to the electric motor and converts direct current (DC) power from the battery pack into alternating current (AC) power for use by the electric motor. According to 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 conduction branch for each phase winding of the electric motor 208. According to various embodiments, the electric motor 208 is a three-phase motor with three phase windings. Thus, the inverter 210 includes three conduction branches.Furthermore, the vehicle electronics 204 includes additional loads 212, which generally have power capacities of +800 V and which are directly connected to the battery pack 206.

[0039] The battery pack 206 may be connected to the charging station 202 by 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 may be arranged in an open configuration to disconnect from the charging station and in a closed configuration to connect to the charging station 202. A bypass line 218 connects from the positive DCFC bus 214 to a phase winding of the electric motor 208, thus providing a second channel for charging the battery pack 206. A bypass switch S3 in the bypass line 218 may be arranged in a closed position to selectively implement the second channel.

[0040] Fig. 3 is a circuit diagram 300 showing details of the electric motor 208 and the inverter 210. The electric motor 208 includes a rotor with a first phase winding 308 (labeled "A"), a second phase winding 310 (labeled "B"), and a third phase winding 312 (labeled "C"). The electric motor 208 is connected to the charging station 202 via the charging bus 304. A filter capacitor 306 controls a voltage level at the electric motor 302 by preventing or reducing spikes in the charging voltage.

[0041] 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.

[0042] The inverter 210 includes a first branch line 318, a second branch line 320, and a third branch line 322, each of which runs between the positive DC voltage bus 314 and the negative DC voltage bus 316. Each branch line includes four switches arranged in a T-configuration. For example, the first branch line 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 electric motor 302 is connected between the first switch X1 and the second switch X2 to a first AC terminal (labeled "A") of the first branch line 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 line branch contains 320 switches X5, X6, X7 and X8 in the T 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 electric motor 302 is connected between switch X5 and switch X6 to a second AC terminal (labeled "B") of the second line branch 320. 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 line branch 322 includes switches X9, X10, X11, and X12 in the T configuration. 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 electric motor 302 is connected between the switch X9 and the switch X10 to a third AC terminal (labeled “C”) of the third line branch 322.The switches X11 and X12 are connected in series between the third AC terminal and the neutral point O of the battery pack 206.

[0043] Fig. 4 is a circuit diagram 400 showing the electric motor 208, the inverter 210, and an inverter control circuit 402. The inverter control circuit 402 is used to control the current flow through the lines of the inverter 210 during a 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 line branch 318, a second control block 406 for controlling the switches (X5, X6, X7, X8) of the second line branch 320, and a third control block 408 for controlling the switches (X9, X10, X11, X12) of the third line branch 322.

[0044] The first control block 404 provides control signals for the switches (X1, X2, X3, X4) as they are grouped into switch pairs, i.e., for a first switch pair [X1, X2] and for a second switch pair [X3, X4]. The first switch pair [X1, X2] is controlled by complementary control inputs. For example, a logic inverter 410 at switch X1 ensures that switch X1 is off when X2 is on and that switch X1 is on when X2 is off. The second switch pair [X3, X4] operates similarly with a logic inverter 410 at the third switch X3. A first comparator 412 receives a first carrier signal T1 and a duty cycle signal and provides an output that is sent to the first switch pair [X1, X2]. Similarly, a second comparator 414 receives the second 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 180 degrees out of phase with the second carrier signal. This results in the 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 in one switching cycle, and switch X2 and switch X4 are 180 degrees out of phase with each other in the same switching cycle.

[0045] The second control block 406 operates similarly to the first control block 404, using a second carrier signal T3 used to control the switch pairs [X5, X6] and [X7, X8]. The carrier signal T3 and the carrier signal T4 are 180 degrees out of phase with each other. Furthermore, the carrier signal T3 is 180 degrees out of phase with the carrier signal T1. According to one embodiment, the duty cycle is a single duty cycle applied via the first control block 404 and the second control block 406. According to another embodiment, the first control block 404 may receive a first duty cycle signal, and the second control block 406 may receive a second duty cycle signal.

[0046] In a charging scenario, the third control block turns off the switches (X9, X10, X11, X12) of the third line branch 322, and the charging station 110 is connected to the third AC port. The first control block 404 and the second control block 406 are used to control the flow of a first current through the first line branch 318 and a second current through the second line branch 320, respectively. According to another embodiment, the first control block 404 turns off the switches (X1, X2, X3, X4) of the first line branch 318, and the charging station 110 is connected to the first AC port. The second control block 406 and the third control block 408 control the flow of current through the second line branch 320 and the third line branch 322, respectively. According to yet another embodiment, the second control block 406 turns off the switches (X5, X6, X7, X8) of the second line branch 320 and the charging station 110 is connected to the second AC connection.The first control block 404 and the third control block 408 control the flow of current through the first line branch 318 and the third line branch 322, respectively.

[0047] Fig. 5 is a circuit diagram 500 showing details for charging a selected battery (e.g., the first battery half-pack 206a) according to one embodiment. The third control block 408 configures the third conduction branch 322 with switches X9 and X10 in an OFF position and with switches X11 and X12 in an ON position. Thus, the charging bus 304 is connected to the neutral point O via switches X11 and X12. The phase winding A 308 is connected to the negative DC voltage bus 316 by the first conduction branch 318 (and switch X2). In this configuration, the charging station 202 is connected only to the first half-pack 206a. A similar configuration of switches can be used to connect the charging station only to the second battery half-pack 206b.

[0048] Fig. 6 shows a phase diagram 600 of the electric motor 302 according to one embodiment. The phase diagram 600 includes a first phase leg A, which represents the current phase through the first phase winding 308, a second phase leg B, which represents the current phase through the second phase winding 310, and a third phase C, which represents the current phase through the third phase winding 312. The phase legs A, B, and C are 120 degrees out of phase with each other. A longitudinal axis 602 (L) and a transverse axis 604 (Q) of a rotor of the electric motor 302 are shown in the phase diagram 600. The longitudinal axis 602 is aligned with the first phase leg A for illustrative purposes. To ensure zero or minimal net torque production at the rotor, the current is controlled to create a net current vector along the L axis. This can be done, for example, by:can be achieved by connecting the charging station to the first phase winding 308 (aligned with the +L axis) and then controlling the negative current (i.e., the current from the charging station to the battery) through the second phase winding B and through the third phase winding C to be equal in magnitude. 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. Thus, the sum of these torque vectors lies along the longitudinal axis 602 (i.e., along the first phase branch A).

[0049] Fig. 7 shows a phase diagram 700 of the electric motor according to another embodiment. The longitudinal axis 602 is oriented opposite the first phase branch A. The current is controlled through the second phase winding B to generate a first positive torque vector 702. Furthermore, the current is controlled through the third phase winding C to generate a second positive torque vector 704. The sum of these torque vectors lies along the longitudinal axis 602 (which is antiparallel to the first phase branch A).

[0050] Fig. 8 shows a phase diagram 800 of the electric motor according to another embodiment. The longitudinal axis 602 of the rotor is not aligned with the phase axes A. The current can be controlled such that different currents are present in the second phase winding B and the third phase winding C, resulting in a first torque vector 802 and a second torque vector 804 having different magnitudes. The summation of these torque vectors results in the combined torque that is along the L-axis. Thus, for any angular position of the L-axis of the rotor, an appropriate line leg of the inverter can be switched off, and the current through the remaining line legs can be approximately controlled to provide the required torque vector along the L-axis.

[0051] Fig. Figure 9 is a circuit diagram 900 showing the inverter in a configuration for charging a single battery half-pack. The DCFC terminal is connected to the phase leg via a switch box 902 containing a first DCFC switch 904, a second DCFC switch 906, and a third DCFC switch 908. The first DCFC switch 904 connects the first line branch 318 and the second line branch 320 via the positive DC voltage bus 314 (i.e., a connection between node H1 and node H2) to the third line branch 322. The second DCFC switch 906 connects the first line branch 318 and the second line branch 320 through the neutral points (i.e., a connection between node M1 and node M2) to the third line branch 322. The third DCFC switch 908 connects the charging bus 304 via the third line branch 322 to the neutral point. Fig. In the configuration shown in Figure 9, 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). Additionally, the third line branch 322 includes switches X9 and X10 arranged in a closed configuration (OFF configuration), and switches X11 and X12 arranged in an open configuration (ON configuration). According to this configuration, the capacitor C2 can be used as a +400V input DC capacitor (i.e., as a filter capacitor for charging).

[0052] Fig.10 shows the inverter 1000 according to another embodiment. The charge bus 304 includes a first charge line 1002 connecting to the second phase winding 310 and a second charge line 1004 connecting to the third phase winding 312. The first charge line 1002 includes a first charge line switch 1006, and the second charge line 1004 includes a second charge line switch 1008. The first charge line switch 1006 and the second charge line switch 1008 are operable to provide a multiplexed input phase, thereby minimizing mechanical stresses on the motor during the charging procedure.

[0053] The terms "a" and "an" do not imply a limitation on the quantity, but rather denote the presence of at least one of the mentioned objects. Unless the context clearly indicates otherwise, the term "or" means "and / or." Reference throughout the specification to "an aspect" means that a particular element described in connection with the aspect (e.g., feature, structure, step, or property) is included in at least one aspect described herein and may or may not be included in other aspects. It is also understood that the described elements according to the various aspects may be combined in any suitable manner.

[0054] When an element, such as a layer, film, region, or substrate, is referred to herein as being "on" another element, it may be directly on top of the other element or there may also be intervening elements. In contrast, when an element is referred to as being "directly on" another element, no intervening elements are present.

[0055] Unless otherwise specified herein, all examination standards are the most recent examination standards in effect as of the filing date of this application or the filing date of the earliest priority application in which the examination standard appears, if priority is claimed.

[0056] Unless otherwise defined, 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.

[0057] Although the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. Furthermore, many changes may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Thus, the present disclosure is not intended to be limited to the particular embodiments disclosed, but is intended to include all embodiments within its scope.

Claims

[1] A method for charging a battery of an electric vehicle, the method comprising: Coupling a charging station to an electric motor of the vehicle, the electric motor being coupled to the battery through a T-bridge multi-level inverter including a first branch circuit having a first set of switches and a first AC terminal coupled to the electric motor, a second branch circuit having a second set of switches and a second AC terminal coupled to the electric motor, and a third branch circuit having a third set of switches and a third AC terminal coupled to the electric motor; Connecting the third AC terminal of the third line branch to the charging station; and Controlling the first set of switches to control a first current through the first AC terminal of the first line branch and / or the second set of switches to control a second current through the second AC terminal of the second line branch to charge the battery via the charging station by the electric motor. [2] The method of claim 1, wherein controlling the first current further comprises controlling a first switching cycle for the first set of switches of the first line branch and controlling the second current further comprises controlling a second switching cycle for the second set of switches of the second line branch. [3] The method of claim 1, wherein the battery includes a first battery half-pack and a second battery half-pack, the method further comprising opening a switch of the third line branch to isolate the first battery half-pack or the second battery half-pack for individual charging. [4] The method of claim 1, wherein the third line branch includes a first pair of switches in series between a positive DC voltage bus and a negative DC voltage bus and a second pair of switches in series between the third AC terminal and the neutral point, the method further comprising: (i) arranging all switches of the third line branch in a closed configuration; or (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 line leg and the third line leg to the charging station using switches operable to multiplex connections of the second line leg and the third line leg to the charging station. [6] A system for charging a battery of a vehicle, the system comprising: an electric motor that can be coupled to a charging station; a T-bridge multi-level inverter including a first line leg with a first set of switches and a first AC terminal coupled to the electric motor, a second line leg with a second set of switches and a second AC terminal coupled to the electric motor, and a third line leg with a third set of switches and a third AC terminal coupled to the electric motor, the T-bridge multi-level inverter configured to couple the electric motor to the battery; a processor configured to: Connecting the third AC terminal of the third line branch to the charging station; and Controlling the first set of switches to control a first current through the first AC terminal of the first line branch and / or the second set of switches to control a second current through the second AC terminal of the second line branch to charge the battery via the charging station by the electric motor. [7] The system of claim 6, wherein the processor is further configured to control the first current by controlling the first switching cycle for the first set of switches of the first line branch and to control the second current by controlling a second switching cycle for the first set of switches of the second line branch. [8] The system of claim 6, wherein the battery includes a first battery half-pack and a second battery half-pack, and wherein the processor is further configured to open a switch of the third line branch to disconnect the first battery half-pack or the second battery half-pack for individual charging. [9] The system of claim 6, wherein the third branch line includes a first pair of switches in series between a positive DC voltage bus and a negative DC voltage bus, and wherein a second pair of switches is connected in series between the third AC terminal and the neutral point, and wherein the processor is further configured to perform: (i) placing all switches of the third branch line in a closed configuration; or (ii) closing the first pair of switches and opening the second pair of switches. [10] The system of claim 6, wherein the processor is further configured to control a first connection between the second line branch and the charging station and a second connection between the third line branch and the charging station to multiplex the operation of the first connection and the second connection.

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