Multifunctional multi-level inverter

Abstract

A method for charging a battery (206) of an electric vehicle, comprising: Coupling a charging station (110, 202) to an electric motor (208, 302) of the electric vehicle, wherein the electric motor (208, 302) is coupled to the battery (206) through a capacitor clamp multi-level inverter having a first section (318) comprising a first set of switches (X1, X2, X3, X4) and a first alternating current (AC) terminal coupled to the electric motor (208, 302), a second section (320) comprising a second set of switches (X5, X6, X7, X8) and a second AC terminal coupled to the electric motor (208, 302), and a third section (322) comprising a third set of switches (X9, X10, X11, X12) and a third AC terminal coupled to the electric motor (208, 302) is, has, comprises; and Controlling at least one of the first set of switches (X1, X2, X3, X4) to control a first current through the first AC terminal of the first section (318) and the second set of switches (X5, X6, X6, X8) to control a second current through the second AC terminal of the second section (320) to charge the battery (206) by means of the charging station (110, 202) through the electric motor (208, 302), characterized by connecting one of the third AC terminals of the third section of the capacitor clamp multi-level inverter and a neutral point (502) of the electric motor (208, 302) to the charging station (110, 202).

Description

INTRODUCTIONThis disclosure relates to charging a battery of an electric vehicle, and more particularly to a method of actuating switches of a multi-stage inverter to control the charging operation.Electric vehicles are manufactured that have battery capacities that exceed the charging capacities of currently available charging stations. To support the backward compatibility of these electric vehicles, many have been equipped with additional vehicle-side electronics in the form of a direct current (DC-DC) converter. However, such additional vehicle electronics are undesirable because they increase the complexity of the vehicle as well as its mass and volume. Accordingly, it is desirable to provide a method of charging the vehicle at currently available charging stations without the need for additional vehicle-side electronics to provide backward compatibility.In the document DE 10 2019 202 173 A1, a circuit arrangement for providing energy for a vehicle is disclosed, which comprises an inverter for charging a battery and for supplying an electric motor with energy. The circuit arrangement is configured to provide the voltage required for charging the battery by means of the inverter for the battery and to provide a voltage required for charging a battery of a further vehicle by means of the inverter.The document DE 10 2018 124 787 A1 discloses a charging device for charging a battery of a vehicle, which has an electric drive motor. The device comprises an inductance and a drive converter for converting battery energy in the drive mode, wherein the inductance and the drive converter serve as step-up converter in the charging mode.SUMMARYIn an exemplary embodiment, a method of charging a battery of an electric vehicle is disclosed. A charging station is coupled to an electric motor of the electric vehicle, the electric motor coupled to the battery through a multi-stage capacitor-clamped inverter comprising a first portion having a first set of switches and a first alternating current (AC) terminal coupled to the electric motor, a second portion having a second set of switches and a second alternating current terminal coupled to the electric motor, and a third portion having a third set of switches and a third alternating current terminal coupled to the electric motor. One of the third AC terminal of the third portion of the multi-stage capacitor-clamped inverter and a neutral point of the electric motor is connected to the charging station. At least one of the first set of switches to control a first current through the first AC terminal of the first portion and the second set of switches to control a second current through the second AC terminal of the second portion is configured to charge the battery by the electric motor via the charging station. At least one of the first set of switches and the second set of switches is controlled to control a first current through the first AC terminal of the first portion and a second current through the second AC terminal of the second portion, respectively, to charge the battery by the electric motor via the charging station.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 portion, and controlling the second current further includes controlling a second switching cycle for the second set of switches of the second portion.In addition to one or more of the features described herein, the first portion includes a switch pair and switches of the switch pair receive inputs phase shifted 180 degrees.In addition to one or more of the features described herein, the method further comprises controlling 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 electric motor.In addition to one or more of the features described herein, wherein the third AC terminal is connected to the charging station, the method further comprises placing each switch of the third set of switches in an open state.In addition to one or more of the features described herein, wherein the third AC terminal is connected to the charging station and the third set of switches includes four switches connected in series, the method further comprises placing a first switch and a third switch of the third section in a closed state and placing a second switch and a fourth switch of the third section in an open state to connect a clamping capacitor of the third section via the charging station.In addition to one or more of the features described herein, wherein the neutral point of the electric motor is connected to the charging station, the method further comprises actuating the first set of switches, the second set of switches, and the third set of switches 120 degrees out of phase.In another exemplary embodiment, a system for charging a battery of a vehicle is disclosed. The system includes an electric motor couplable to a charging station, a multi-stage inverter with capacitor clamping, and a processor. The multi-stage capacitor-clamped inverter is configured to couple the electric motor to the battery and includes a first portion having a first set of switches and a first AC terminal coupled to the electric motor, a second portion having a second set of switches and a second AC terminal coupled to the electric motor, and a third portion having a third set of switches and a third AC terminal coupled to the electric motor. The processor is configured to connect one of the third AC terminal of the third portion of the multi-stage capacitor-clamped inverter and a neutral point of the electric motor to the charging station and control at least one of the first set of switches to control a first current through the first AC terminal of the first portion and the second set of switches to control a second current through the second AC terminal of the second portion to charge the battery through the electric motor via the charging station.In addition to one or more of the features described herein, the processor is further configured to control the first current by controlling a first switching cycle for the first set of switches of the first portion and to control the second current by controlling a second switching cycle for the second set of switches of the second portion.In addition to one or more of the features described herein, the first portion 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 inputs phase shifted by 180 degrees.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 generate a net zero torque at the electric motor for any angular position of a rotor of the electric motor.In addition to one or more of the features described herein, the third AC terminal is connected to the charging station and the processor is further configured to place each switch of the third set of switches in an open state.In addition to one or more of the features described herein, the third AC terminal is connected in series with the charging station, the third set of switches includes four switches, and the processor is further configured to place a first switch and a third switch of the third section in a closed state and place a second switch and a fourth switch of the third section in an open state to connect a clamping capacitor of the third section via the charging station.In addition to one or more of the features described herein, the neutral point of the electric motor is connected to the charging station, and the processor is further configured to actuate the first set of switches, the second set of switches, and the third set of switches 120 degrees out of phase with respect to one another.In yet another exemplary embodiment, a vehicle is disclosed. The vehicle includes a battery, an electric motor couplable to a charging station, a multi-stage inverter with capacitor clamping, and a processor. The multi-stage capacitor-clamped inverter is configured to couple the electric motor to the battery and includes a first portion having a first set of switches and a first AC terminal coupled to the electric motor, a second portion having a second set of switches and a second AC terminal coupled to the electric motor, and a third portion having a third set of switches and a third AC terminal coupled to the electric motor. The processor is configured to connect one of the third AC terminal of the third portion of the multi-stage capacitor-clamped inverter and a neutral point of the electric motor to the charging station and control at least one of the first set of switches to control a first current through the first AC terminal of the first portion and the second set of switches to control a second current through the second AC terminal of the second portion to charge the battery through the electric motor via the charging station.In addition to one or more of the features described herein, the processor is further configured to control the first current by controlling a first switching cycle for the first set of switches of the first portion and to control the second current by controlling a second switching cycle for the first set of switches of the second portion.In addition to one or more of the features described herein, the first portion 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 inputs phase shifted by 180 degrees.In addition to one or more of the features described herein, the processor is further configured to control a phase between the first current and the second current to generate a net zero torque at the electric motor for any angular position of a rotor of the electric motor.In addition to one or more of the features described herein, the third AC terminal is connected to the charging station, wherein the third set of switches includes four switches in series, and the processor is further configured to place each switch of the third set of switches in an open state.In addition to one or more of the features described herein, the third AC terminal is connected to the charging station, wherein the third set of switches includes four switches in series, and the processor is further configured to place a first switch and a third switch of the third section in a closed state and place a second switch and a fourth switch of the third section in an open state to connect a clamping capacitor of the third section via the charging station.In addition to one or more of the features described herein, the neutral point of the electric motor is connected to the charging station, and the processor is further configured to actuate the first set of switches, the second set of switches, and the third set of switches 120 degrees out of phase with respect to one another.The above-described features and advantages and other features and advantages of the disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSOther features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings, in which: FIG. 1 illustrates a vehicle according to an example embodiment; FIG. 2 shows a charging circuit for charging the electric vehicle in an embodiment; FIG. 3 is a schematic diagram showing details of the electric motor and the inverter; FIG. 4 is a schematic diagram showing the electric motor, the inverter, and an inverter control circuit; FIG. 5 is a schematic diagram showing details of the electric motor, the inverter, and the inverter control circuit in another embodiment; FIG. 6 is a phase diagram of the electric motor in an embodiment; FIG. 7 shows a phase diagram of the electric motor in a further embodiment; FIG. 8 is a phase diagram of the electric motor in another embodiment; FIG. 9 illustrates the inverter in a configuration for charging the battery using a three-phase electric motor in another embodiment; FIG. 10 illustrates the inverter in a configuration for charging the battery using a three-phase electric motor in another embodiment; and FIG. 11 shows the inverter in a further embodiment.DETAILED DESCRIPTIONThe 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 similar or corresponding portions and features.According to an exemplary embodiment, FIG. 1 shows a vehicle 10 including a vehicle body 12 at least partially defining a passenger compartment 14. The vehicle body 12 also supports various vehicle subsystems including a propulsion system 16 and other subsystems to assist functions of the propulsion system 16, and other vehicle components such as a brake subsystem, a suspension system, a steering subsystem, and others.The vehicle 10 may be an electric powered vehicle (EV), a hybrid vehicle, or another vehicle. In one embodiment, the vehicle 10 is an electric vehicle that includes multiple motors and / or propulsion systems. Any number of drive units, such as one or more drive units for applying torque to front wheels (not shown) and / or rear wheels (not shown), may be included. The propulsion units are controllable to operate the vehicle 10 in various operating modes such as a normal mode, a high power mode (in which additional torque is applied), an all-wheel drive ("AWD"), a front-wheel drive ("FWD"), a rear-wheel drive ("RWD"), and others.For example, propulsion system 16 is a multiple propulsion 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., power inverter units or PIMs) each set a DC power (DC power) from a high voltage battery (HV) system 40 to polyphase AC power (e.g., two-phase AC power, three-phase AC power, six-phase AC power, etc.) (Multi-Phase AC Power) to Drive the Front Electric Motor 22 and the Rear Electric Motors 32L and 32R.As shown in FIG. 1, the drive systems include separate electric motors. However, embodiments are not so limited. For example, rather than separate motors, multiple drives may be provided by a single machine having multiple sets of windings that are physically independent.As also shown 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, embodiments are not so limited as any number of drive systems and / or motors may be present at different locations (e.g., one motor driving each wheel, partner motors per axle, etc.). In addition, embodiments are not limited to a dual propulsion system, as embodiments may be used with a vehicle having any number of motors and / or power inverters.In the propulsion system 16, the front drive unit 20, the left rear drive unit 30L, and a 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, and others. The battery system 40 may be configured as a rechargeable energy storage system (RESS).In one embodiment, the battery system 40 includes a plurality of separate battery assemblies, each battery assembly being independently chargeable and usable 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). In various embodiments, one or more of the battery packs may include a MODACS battery (a multi-output, dynamically adjustable capacity battery) as described herein with reference to FIGS. 2-4.Each of the front electric motor 22 and the rear electric motors 32L and 32R is a three-phase motor having three-phase motor windings. However, embodiments described herein are not so limited. For example, the motors may be any polyphase machines powered by polyphase inverters and the drive units may be realized using a single machine having independent sets of windings.The battery system 40 and / or propulsion system 16 includes 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 devices may also be operated to selectively connect the first battery sub-pack 44 and the second battery sub-pack 46 to a charging system. The charging system may be used to charge the first battery sub-pack 44 and the second battery sub-pack 46 and / or supply power from the first battery sub-pack 44 and / or the second battery sub-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 vehicle-mounted 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 commercial AC power supply. A second OBCM 53 may be included for DC charging (e.g., fast DCFC charging). As shown in FIG. 1, the utility AC power supply is a charging station 110 connected to the charging port 54 via a cable 112.In one embodiment, the switching system includes a first switching device 60 that selectively connects the first battery sub-pack 44 to the inverters 24, 34L, and 34R, and a second switching device 62 that selectively connects the second battery sub-pack 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 sub-pack 44 in series with the second battery sub-pack 46.Any of various controllers may be used to control functions of the battery system 40, the switching system, and the drive units. A controller includes any suitable processing device or processing unit and may use an existing controller, such as a propulsion system controller, a RESS controller, and / or controller in the propulsion system. For example, a controller 65 may be included for controlling shift and drive control operations, as discussed herein.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) having memory executing one or more software or firmware programs, combinatorial 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 of charging a battery according to one or more embodiments described in detail herein. Such a method includes operating various control blocks and switches of the vehicle as discussed herein.FIG. 2 shows a charging circuit 200 for charging the electric vehicle 10 in one embodiment. The charging circuit 200 shows the charging station 202 and vehicle electronics 204. The vehicle electronics 204 includes a battery 206 or power source, an electric motor 208, and an inverter 210 that couples the battery to the electric motor and converts direct current (DC) power from the battery to alternating current (AC) power for use with the motor. In various embodiments, the battery 206 is a single battery or multiple batteries having a total voltage capacity of +800 volts. The inverter 210 is a multi-stage capacitor-clamped inverter that includes a portion for each phase winding of the electric motor 208. In various embodiments, the electric motor 208 is a three-phase motor having three-phase windings. Thus, the inverter 210 includes three sections. The vehicle electronics 204 further include accessory loads 212 that generally have +800V power capacities and that are directly connected to the battery 206.The battery may be connected to the charging station by a positive DCFC bus 214 and a negative DCFC bus 216. The positive DCFC bus 214 includes a first switch S 1 and the negative DCFC bus 216 includes a second switch S 2 that are placed in an open configuration to disconnect from the charging station and a closed configuration to connect to the charging station. A bypass line 218 connects from the positive DCFC bus 214 to a phase winding of the electric motor 208 and thus provides a second channel for charging the battery 206. A bypass switch S3 on the bypass line 218 may be placed in a closed position to selectively implement the second channel.FIG. 3 is a schematic diagram 300 showing details of the electric motor 208 and the inverter 210. The electric motor 208 includes a rotor having a first phase winding 308 (referred to as "A"), a second phase winding 310 (referred to as "B"), and a third phase winding 312 (referred to as "C"). The electric motor 208 connects 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 peaks of the charging voltage.The inverter 210 is connected to the battery 206 by a positive DC bus 314 and a negative DC bus 316. The inverter 210 includes a first portion 318, a second portion 320, and a third portion 322 that each extend between the positive DC bus 314 and the negative DC bus 316. Each section includes four switches in series and a clamping capacitor. For example, the first portion 318 includes switches X 1, X 2, X 3, and X 4. The first phase winding 308 of the electric motor 302 connects to the first portion 318 at a first AC connection between the second switch X 2 and third switch X 3. A first clamping capacitor 324 (referred to as "C3") is connected at one end between the first switch X1 and the second switch X2 and at another end between the third switch X3 and the fourth switch X4. Similarly, the second portion 320 includes switches X 5, X 6, X 7, and X 8 with a second clamping capacitor 326. The second phase winding 310 of the electric motor 302 connects to the second portion 320 at a second AC terminal between the switch X 6 and the switch X 7. The third section 322 includes switches X 9, X 10, X 11, and X 12 with a third clamping capacitor 328. The third phase winding 312 of the electric motor 302 connects to the third portion 322 at a third AC terminal between the switch X 10 and the switch X 11.FIG. 4 is a schematic 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 flow of current through the portions of the inverter during a charging scenario for the battery. The inverter control circuit 402 includes a first control block 404 for controlling the switches (X 1, X 2, X 3, X 4) of the first portion 318, and a second control block 406 for controlling the switches (X 5, X 6, X 7, X 8) of the second portion 320. Although not shown in FIG. 4, a third control block may be used to control the switches (X 9, X 10, X 11, X 12) of the third portion 322.The operation of the control blocks will be discussed using the first control block 404 as an illustrative example. The first control block 404 supplies control signals to the switches (X1, X2, X3, X4) grouped as pairs of switches, namely a first pair of switches [X1, X4] and a second pair of switches [X2, X3].The first switch pair [X1, X4] is driven by complementary control inputs. For example, a logic inverter 408 at switch X 4 ensures that switch X 4 is off when X 1 is on and switch X 4 is on when X 1 is off. The second pair of switches [X2, X3] operate respectively with a logic inverter 410 at the third switch X3.A first control branch of the first control block 404 includes a first carrier signal T 1 that provides a first switching cycle that is input to a first comparator 412. The first comparator 412 also receives a duty cycle cycle signal and compares the first carrier signal T 1 with the duty cycle cycle signal to provide an output that is sent to the first switch pair [X 1, X 4].Accordingly, a second control branch of the first control block 404 includes a second carrier signal T 2 that provides a second switching cycle that is input to a second comparator 414. The second comparator also receives the same duty cycle signal and compares the second carrier signal T 2 with the duty cycle signal to provide an output that is sent to the second switch pair [X 2, X 3]. The first carrier signal is 180 degrees out of phase with the second carrier signal. This results in switch pairs [X1, X4] and [X2, X3] that are 180 degrees out of phase with each other. In other words, the switch X 1 and the switch X 2 are 180 degrees out of phase with each other in a switching cycle, and the switch X 3 and the switch X 4 are 180 degrees out of phase with each other in the switching cycle.The second control block 406 operates similar to the first control block 404 using carrier signals T 3 and T 4 including the switch pairs [X 5, X 8] and X 8, respectively. [X6, X7]. The carrier signal T 3 and the carrier signal T 4 are 180 degrees out of phase with respect to each other. In addition, the carrier signal for T3 is 180 degrees out of phase with respect to the carrier signal T1. In one embodiment, the duty cycle cycle is a single duty cycle cycle applied via the first control block 404 and the second control block 406 (and the third control block, if necessary). The first control block 404 and the second control block 406 may receive either the same duty cycle cycle signal or different duty cycle cycle signals.In a charging scenario, the switches (X 9, X 10, X 11, X 12) of the third branch are all turned off and the charging station ICH 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 a first stream through the first section 318 and a second stream through the second section 320, respectively. In another embodiment, the switches of the first portion 318 may be turned off and the charging station ICH is connected to the first AC terminal, while the second control block 406 and the third control block are used to control the flow of a current through the second portion 320 and a current through the third portion 322, respectively. In yet another embodiment, the switches of the second branch may be turned off and the charging station I is connected in CH with the second AC terminal, while the first control block 404 and the third control block are used to control the flow of current through the first portion 318 and current through the third portion 322, respectively.FIG. 5 is a schematic diagram 500 showing details of the electric motor 208, the inverter 210, and the inverter control circuit 402 in another embodiment. The electric motor 208 includes a first phase winding A 308, a second phase winding B 310, a third phase winding C 312, and a neutral point 502. The neutral point 502 of the electric motor 208 connects to the charging station through the charging bus 304.The inverter control circuit 402 includes a first control block 404 for controlling the switches (X 1, X 2, X 3, X 4) of the first section 318, a second control block 406 for controlling the switches (X 5, X 6, X 7, X 8) of the second section 320, and a third control block 504 for controlling the switches (X 9, X 10, X 11, X 12) of the third section 322. Each control block is driven by an independent duty cycle cycle signal (i.e., a first duty cycle cycle signal D 1 for the first control block 404, a second duty cycle cycle signal D 2 for the second control block 406, and a third duty cycle cycle signal D 3 for the third control block 504).The first control block 404 is operated such that the switch pairs [X1, X4] and [X2, X3] are 180 degrees out of phase with each other, as discussed with reference to FIG. 4. Accordingly, the second control block 406 is operated such that the switch pairs [X 5, X 8] and [X 6, X 7] are 180 degrees out of phase with each other, and the third control block 504 is operated such that the switch pairs [X 9, X 12] and [X 10, X 11] are 180 degrees out of phase with each other. The first control block 404, the second control block 406, and the third control block 504 are operated 120 degrees out of phase. For example, the carrier signal T 3 tracks the carrier signal T 1 120 degrees in phase and the carrier signal T 5 tracks the carrier signal T 3 120 degrees in phase.FIG. 6 shows a phase diagram 600 of the electric motor 302, in one embodiment. Phase diagram 600 includes a first phase leg A representing the current phase through first phase winding 308, a second phase leg B representing the current phase through second phase winding 310, and a third phase leg C representing the current phase through third phase winding 312. The phase legs A, B and C are phase-shifted 120 degrees from each other. A direct axis 602 (D) and a quadrature axis 604 (Q) of a rotor of the electric motor 302 are shown in phase diagram 600. The direct axis 602 is illustratively aligned along the first phase branch A. To ensure net zero torque production or minimum torque production at the rotor, the current is controlled to generate a net current vector along the D-axis. This may be accomplished, for example, by connecting the charging station to the first phase winding 308 (which is aligned with the +D axis) and then controlling the negative current (i.e., the current from the charging station to the battery) to have the same magnitude through the second phase winding B and the third phase winding C. 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 direct axis 602 (i.e., along the first phase branch A).FIG. 7 shows a phase diagram 700 of the electric motor in a further embodiment. The direct axis 602 is oriented opposite to the first phase branch A. Current is controlled by the second phase winding B to generate a first positive torque vector 702. Current is also controlled by the third phase winding C to generate a second positive torque vector 704. The sum of these torque vectors lies along the direct axis 602 (which lies anti-parallel to the first phase branch A).FIG. 8 shows a phase diagram 800 of the electric motor in a further embodiment. The direct axis 602 of the rotor is not aligned with the phase axes A. The current may 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 lies along the D axis. Thus, for any angular position of the D-axis of the rotor, an appropriate portion of the inverter may be turned off and the current through the remaining portions may be controlled appropriately to provide the required torque vector along the D-axis.FIG. 9 shows the inverter 900 in a configuration for charging the battery using a three-phase electric motor in another embodiment. In the third section 322, the switches X 9 and X 11 are set to an OFF state and the switches X 10 and X 12 are set to an ON state. A first auxiliary branch 902 connects the positive DC bus 314 either at the third AC terminal (as shown) or to a node between the switch X 9 and the switch X 10. A first auxiliary arm switch SW1 is used to control the connection of the first auxiliary arm 902. Due to the configuration of the switches (X 9, X 10, X 11, X 12) along the third portion 322, opening the first auxiliary branch switch SW 1 sets the voltage (V A) along the third phase winding 322 to V+ and closing the first auxiliary branch switch SW 1 charges the clamping capacitor C 2, which sets the voltage (V A) along the third phase winding 322 to the voltage of the capacitor (V C2). The first control block 404 and the second control block 406 control the flow of the current through the first portion 318 and the second portion 320, respectively. The clamping capacitor C 2 may thus take the place of the filtering capacitor 306 (FIG. 3 ) to filter the DCFC from the charging station 110 during a charging operation.FIG. 10 shows the inverter 1000 in a configuration for charging the battery using a three-phase electric motor in another embodiment. In the third section 322, the switches X 9 and X 11 are set to an OFF state and the switches X 10 and X 12 are set to an ON state. A first auxiliary branch 902 connects the positive DC bus 314 either at the third AC terminal (as shown) or to a node between the switch X 9 and the switch X 10. In the second section 320, the switches X 5 and X 7 are set to an OFF state and the switches X 6 and X 8 are set to an ON state. A second auxiliary branch 1002 connects the positive DC bus 314 either at the second AC terminal (as shown) or to a node between the switch X 5 and the switch X 6. The first control block 404 controls the flow of current through the first section 318. With the switches SW 1 and SW 2 in a closed configuration, the capacitors C 2 and C 3 are combined to serve as the filter capacitor 306 (FIG. 3 ) to filter the DCFC from the charging station 110 during a charging operation.FIG. 11 shows the inverter 1100 in a further embodiment. The charging bus 304 includes a first charging line 1102 that connects to the second phase winding 310 and a second charging line 1104 that connects to the third phase winding 312. The first charge line 1102 includes a first charge line switch 1106 and the second charge line 1104 includes a second charge line switch 1108. The first charge line switch 1106 and the second charge line switch 1108 may be actuated to provide a multiplexed input phase, thereby minimizing the stresses on the motor during the charging procedure.The terms "a" and "an" do not denote a limitation of a number, but rather denote the presence of at least one of the referenced element. The term "or" means "and / or" unless clearly indicated otherwise by context. Reference throughout the specification to "one aspect" or "an aspect" means that a particular element (e.g., feature, structure, step, or characteristic) described in connection with the aspect is included in at least one aspect described herein and may or may not be present in other aspects. In addition, it is to be understood that the described elements in the various aspects may be combined in any suitable manner.When an element such as a layer, a thin layer, a region or a substrate is referred to as being "on" another element, it may be directly disposed on the other element or intervening elements may also be present. On the other hand, when an element is referred to as being "directly on" another element, there are no intervening elements present.Unless otherwise specified herein, all test standards are the most recently valid standard at the filing date of this application or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.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.

Claims

A method of charging an electric vehicle battery (206), comprising: coupling a charging station (110, 202) to an electric motor (208, 302) of the electric vehicle, the electric motor (208, 302) coupled to the battery (206) through a multi-stage capacitor-clamped inverter having a first portion (318) having a first set of switches (X1, X2, X3, X4) and a first AC terminal (AC terminal) coupled to the electric motor (208, 302), a second portion (320) having a second set of switches (X5, X6, X7, X8) and a second AC terminal coupled to the electric motor (208, 302), and a third portion (322) having a third set of switches (X9, X10, X11, X12), and having a third AC terminal coupled to the electric motor (208, 302); and controlling at least one of the first set of switches (X1, X2, X3, X4) to control a first current through the first AC terminal of the first section (318) and the second set of switches (X5, X6, X6, X8) to control a second current through the second AC terminal of the second section (320) to charge the battery (206) by the electric motor (208, 302) via the charging station (110, 202), characterized by receiving one of the third AC terminal of the third section of the multi-stage capacitor-clamping inverter and a neutral point (502) of the electric motor (208, 302) by the charging station (110, 202).The method of claim 1, wherein controlling the first current further comprises controlling a first switching cycle for the first set of switches (X1, X2, X3, X4) of the first portion (318), and controlling the second current further comprises controlling a second switching cycle for the second set of switches (X5, X6, X7, X8) of the second portion (320).The method of claim 1, wherein the third AC terminal is connected to the charging station (110, 202), further comprising placing each switch (X9, X10, X11, X12) of the third set of switches (X9, X10, X11, X12) in an open state.The method of claim 1, wherein the third AC terminal is connected to the charging station (110, 202) and the third set of switches (X9, X10, X11, X12) includes four switches (X9, X10, X11, X12) connected in series, further comprising placing a first switch (X9) and a third switch (X11) of the third section (322) in a closed state and placing a second switch (X10) and a fourth switch (X12) of the third section (322) in an open state to connect a clamping capacitor of the third section (322) via the charging station (110, 202).The method of claim 1, wherein the neutral point (502) of the electric motor (208, 302) is connected to the charging station (110, 202), further comprising actuating the first set of switches (X1, X2, X3, X4), the second set of switches (X5, X6, X7, X8), and the third set of switches (X9, X10, X11, X12) 120 degrees out of phase with each other.A system for charging a battery (206) of a vehicle (10), comprising: an electric motor (208, 302) couplable to a charging station (110, 202); a multi-stage capacitor-clamped inverter comprising a first portion (318) having a first set of switches (X1, X2, X3, X4) and a first AC terminal coupled to the electric motor (208, 302), a second portion (320) having a second set of switches (X5, X6, X7, X8) and a second AC terminal coupled to the electric motor (208, 302), and a third portion (322) having a third set of switches (X9, X10, X11, X12) and a third AC terminal coupled to the electric motor (208, 302), wherein the multi-stage capacitor-clamped inverter is configured to couple the electric motor (208, 302) to the battery (206); and a processor configured to: control at least one of the first set of switches (X1, X2, X3, X4) to control a first current through the first AC terminal of the first section (318) and the second set of switches (X5, X6, X7, X8) to control a second current through the second AC terminal of the second section (320) to charge the battery (206) by the electric motor (208, 302) via the charging station (110, 202); characterized in that the processor is configured to connect one of the third AC terminal of the third section of the multi-stage inverter to capacitor clamping and a neutral point (502) of the electric motor (208, 302) to the charging station (110, 202).The system of claim 6, wherein the processor is further configured to control the first current by controlling a first switching cycle for the first set of switches (X1, X2, X3, X4) of the first portion (318) and to control the second current by controlling a second switching cycle for the second set of switches (X5, X6, X7, X8) of the second portion (320).The system of claim 6, wherein the third AC terminal is connected to the charging station (110, 202), and the processor is further configured to place each switch (X9, X10, X11, X12) of the third set of switches (X9, X10, X11, X12) in an open state.The system of claim 6, wherein the third AC terminal is connected to the charging station (110, 202), the third set of switches (X9, X10, X11, X12) includes four switches (X9, X10, X11, X12) connected in series, and the processor is further configured to place a first switch (X9) and a third switch (X11) of the third portion (322) in a closed state and place a second switch (X10) and a fourth switch (X12) of the third portion (322) in an open state to connect a clamping capacitor of the third portion (322) via the charging station (110, 202).The system of claim 6, wherein the neutral point (502) of the electric motor (208, 302) is connected to the charging station (110, 202), and the processor is further configured to actuate the first set of switches (X1, X2, X3, X4), the second set of switches (X5, X6, X7, X8), and the third set of switches (X9, X10, X11, X12) 120 degrees out of phase with respect to one another.

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