Hybrid chemical battery power transfer employing multi-level t-inverter

Abstract

A vehicle system includes a first battery pack connected to a second battery pack via a T-type multilevel inverter. The multi-level inverter has a plurality of inverter branches, wherein each inverter branch is arranged in a T-type topology. The motor is connected to the multi-level inverter, and the controller is connected to the motor and the multi-level inverter. The controller includes a memory storing instructions configured to cause the controller to control the multilevel inverter as a direct current (DC)-DC converter such that circulating current passes through the motor, the first battery pack, and the second battery pack.

Description

Technical Field

[0001] The subject disclosure relates to balancing and transferring power between mixed chemistry battery packs using multi-level inverters operating as direct current (DC)-DC converters. Background Art

[0002] Vehicles, including electric vehicles and hybrid electric vehicles, have battery storage systems for purposes such as powering electric motors, electronic devices, and other vehicle subsystems. Batteries used in battery storage systems typically include a plurality of different power cells, each of which stores power for later distribution. The power cells are electrically connected to provide output power to a power distribution bus on demand. During or shortly after charging the battery storage system, it is desirable to ensure that power is properly distributed between the battery packs in order to ensure optimal operation of the battery storage system. Existing systems utilize the same battery cell type (called chemical substance) within the battery pack. Passive power balancing techniques can be used to balance battery cells of the same type.

[0003] Different types of battery packs have different characteristics, such as charging rate and power density. In some configurations, it may be advantageous to utilize different types of battery packs within a single battery system, thereby allowing different vehicle operating modes to utilize different battery characteristics. However, utilizing different battery pack types within a single battery storage system makes power transfer and power balancing between battery packs difficult, and existing passive balancing systems cannot effectively transfer power between battery packs of different chemistries.

[0004] Therefore, it is desirable to provide an active power balancing system for a vehicle battery storage system that includes multiple different types of battery packs. Summary of the invention

[0005] In an exemplary embodiment, a vehicle system includes a first battery pack connected to a second battery pack via a T-type multilevel inverter having a plurality of inverter branches. Each inverter branch is arranged in a T-type topology. An electric motor is connected to the T-type multilevel inverter. A controller is connected to the electric motor and the T-type multilevel inverter. The controller includes a memory storing instructions, the instructions being configured to cause the controller to control the T-type multilevel inverter as a direct current (DC)-DC converter so that a circulating current passes through the electric motor, the first battery pack, and the second battery pack.

[0006] In addition to one or more features described herein, each inverter branch of the T-type multilevel inverter includes a first transistor connecting a positive node to a corresponding AC output node of the inverter branch, a second transistor connecting the corresponding AC output node to a low node, a pair of third transistors and a fourth transistor connecting the corresponding AC output node to a midpoint of a pair of DC link capacitors. Each phase of the motor is connected to a corresponding branch of the multilevel inverter.

[0007] In addition to one or more features described herein, the motor is a four-terminal motor, and controlling the T-type multilevel inverter as a DC-DC converter includes providing a first control signal to the first transistor and the second transistor of each inverter branch, the first control signal being inverted for the second transistor of each inverter branch, providing a second control signal to the third transistor and the fourth transistor of each inverter branch, wherein the second control signal is inverted for the fourth transistor of each inverter branch, and the first control signal is modulated with a three-phase DC-DC converter pulse width modulation (PWM), wherein the PWM of each inverter branch is phase-shifted by 120 degrees from each other inverter branch.

[0008] In addition to one or more features described herein, the motor is a three-terminal motor. Controlling the T-type multilevel inverter as a DC-DC converter includes: for each of the first inverter branch and the second inverter branch, providing a first control signal to the first transistor and the second transistor, wherein the first control signal is inverted for the first transistor of each inverter branch, and providing a second control signal to the third transistor and the fourth transistor of the first inverter branch and the second inverter branch, wherein the second control signal is inverted for the third transistor of each of the first inverter branch and the second inverter branch. The first control signal and the second control signal control the open / closed state of the first transistor, the second transistor, the third transistor, and the fourth transistor of the corresponding phase via pulse width modulation. The modulated first control signal and the modulated second control signal in each inverter branch are phase-shifted 180 degrees relative to the modulated first control signal and the modulated second control signal of the inverter branch. A third control signal is provided to the first transistor, the second transistor, the third transistor and the fourth transistor of the third inverter branch, the third control signal setting the first transistor, the second transistor, the third transistor and the fourth transistor to be turned off for a duration of controlling the T-type multilevel inverter as the DC-DC converter. The third inverter branch is connected to the positive terminal of the first battery pack.

[0009] In addition to one or more features described herein, the first battery pack and the second battery pack are connected in parallel at one or both of the negative battery terminal and the positive battery terminal.

[0010] In addition to one or more features described herein, the first battery pack and the second battery pack are connected in series via a common node.

[0011] In addition to one or more features described herein, a neutral node connecting each phase of the electric motor is connected to a common node of the first battery pack and the second battery pack.

[0012] In addition to one or more features described herein, phase terminals of the electric motor are connected to a common node of the series connected battery pack.

[0013] In addition to one or more features described herein, the motor is a three-terminal motor, a first inverter branch is physically disposed closer to the first battery pack and closer to the second battery pack than each of the second inverter branch and the third inverter branch, and wherein during operation of the DC-DC converter, the first inverter branch is connected to the positive terminal of the first battery pack.

[0014] In addition to one or more of the features described herein, the motor is a three-terminal motor and wherein a first of the three multilevel inverter branches is connected to a positive DC bus via a first switch, a neutral return node of the first branch is connected to neutral via a second switch and to a positive terminal of the first battery pack via a third switch.

[0015] In addition to one or more features described herein, the first battery pack includes at least a first group of power cells and a second group of power cells connected to the first group of power cells at a low node.

[0016] In another exemplary embodiment, a method for transmitting power between a first battery pack and a second battery pack of a vehicle system includes: causing a controller to control a T-type multilevel inverter as a direct current (DC)-DC converter so that a circulating current passes through the T-type multilevel inverter, a motor having three phases, a first battery pack, and a second battery pack. The first battery pack is connected to the second battery pack via the T-type multilevel inverter. The motor is connected to the T-type multilevel inverter, and the motor controller is connected to the motor and the T-type multilevel inverter. The motor controller includes a memory storing instructions configured to cause the vehicle system to implement the method.

[0017] In addition to one or more features described herein, a T-type multilevel inverter includes three inverter branches, each inverter branch includes a first transistor connecting the positive node to the AC output node, a second transistor connecting the AC output node to the low node, a pair of third transistors and a fourth transistor connecting the AC output node to the midpoint of a pair of DC link capacitors, and wherein each phase of the motor is connected to a corresponding branch of the T-type multilevel inverter.

[0018] In addition to one or more features described herein, the motor is a four-terminal motor, and wherein controlling the T-type multilevel inverter as a DC-DC converter includes: providing a first control signal to the first transistor and the second transistor of each inverter branch, wherein the first control signal is inverted for the second transistor of each inverter branch, and providing a second control signal to the third transistor and the fourth transistor of each inverter branch, wherein the second control signal is inverted for the fourth transistor of each inverter branch. The first control signal is modulated with a three-phase DC-DC converter pulse width modulation (PWM), wherein the PWM of each inverter branch is phase-shifted by 120 degrees from each other inverter branch.

[0019] In addition to one or more features described herein, the motor is a three-terminal motor. Controlling the T-type multilevel inverter as a DC-DC converter includes: for each of a first inverter branch and a second inverter branch, providing a first control signal to the first transistor and the second transistor of each of the first inverter branch and the second inverter branch, wherein the first control signal is inverted for the first transistor of each inverter branch, and providing a second control signal to the third transistor and the fourth transistor of the first inverter branch and the second inverter branch. The second control signal is inverted for the third transistor of each of the first inverter branch and the second inverter branch. The first control signal and the second control signal control the open / closed state of the first transistor, the second transistor, the third transistor and the fourth transistor of the corresponding inverter branch via pulse width modulation (PWM). The modulated first control signal and the modulated second control signal in each inverter branch are phase-shifted by 180 degrees from the first modulated control signal and the second modulated control signal of another inverter branch. In addition, a third control signal is provided to the first transistor, the second transistor, the third transistor and the fourth transistor of the third inverter branch, the third control signal setting the first transistor, the second transistor, the third transistor and the fourth transistor to be turned off for a duration of controlling the multilevel inverter as the DC-DC converter. The third inverter branch is connected to the positive terminal of the first battery pack.

[0020] In addition to one or more features described herein, the first battery pack and the second battery pack are connected in parallel.

[0021] In addition to one or more features described herein, the first battery pack and the second battery pack are connected in series via a battery node.

[0022] In addition to one or more features described herein, the first battery is of a first chemistry and the second battery is of a second chemistry different than the first chemistry.

[0023] In yet another exemplary embodiment, a vehicle includes an electric drive system and a power distribution system, the electric drive system including at least one electric motor having three phases, the power distribution system including at least a first battery pack and a second battery pack, the power distribution system being connected to the electric drive system via a T-type multilevel inverter, and a controller being connected to the electric motor and the T-type multilevel inverter. The controller includes a memory storing instructions configured to cause the controller to control the T-type multilevel inverter as a direct current (DC)-DC converter so that a circulating current passes through the electric motor, the first battery pack, and the second battery pack.

[0024] In addition to one or more features described herein, the T-type multilevel inverter includes three inverter branches, each inverter branch of the T-type multilevel inverter includes a first transistor connecting the positive node to the AC output node, a second transistor connecting the AC output node to the low node, a pair of third transistors and a fourth transistor connecting the AC output node to the midpoint of a pair of DC link capacitors, and each phase of the motor is connected to a corresponding branch of the T-type multilevel inverter.

[0025] 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

[0026] Other features, advantages and details appear, by way of example only, from the following detailed description, which refers to the accompanying drawings, in which:

[0027] Figure 1 is a schematic diagram of a vehicle including a power distribution system;

[0028] Figure 2 is a block diagram of a battery system according to one embodiment;

[0029] Figure 3 is a circuit diagram representation of a power transmission method applied to parallel arranged battery packs according to a first example;

[0030] Figure 4is a circuit diagram representation of a power transmission method applied to parallel arranged battery packs according to a second example;

[0031] Figure 5 is a circuit diagram of a power transmission method applied to a battery pack arranged in series according to a first example;

[0032] Figure 6 is a circuit diagram of a power transmission method applied to a battery pack arranged in series according to a second example; and

[0033] Figure 7 is an exemplary physical capacitor mounting configuration according to one example.

[0034] Figure 8 is used Figure 7 An exemplary circuit diagram of a power transmission method applied with a three-terminal motor and capacitor mounting configuration. DETAILED DESCRIPTION

[0035] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses.

[0036] It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features. As used herein, the term module refers to a processing circuit, which 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.

[0037] According to an exemplary embodiment, a vehicle system for a battery includes a plurality of battery packs having different battery pack chemistries. A multilevel inverter converts direct current (DC) power from the battery pack into an alternating current (AC) power form, which is provided to a motor and drives the motor to rotate. The characteristics of the motor rotation are controlled by the characteristics of the AC power signal. A motor controller actively controls switching within the multilevel inverter to control the characteristics of the AC power signal.

[0038] The memory is configured so that the motor controller achieves power balancing or power transfer between different battery packs by operating the multilevel inverter as a DC-DC converter and utilizing the internal inductance of the motor leg without rotating the motor for the DC-DC inverter inductor. By controlling the phase shift in the modulation of the AC inverter when the AC inverter is operated as a DC-DC converter, the internal inductance of the motor leg can be utilized without causing rotation, so that the rotational force generated by the current through the leg is directly offset by the rotational force generated by the current through the other legs of the motor. The DC-DC converter is then able to transfer power between the battery packs according to a known power transfer process.

[0039] In some examples, switches incorporated to facilitate operation in DC-DC converter mode may be further used to provide fault protection and / or isolation of one or more branches during a fault condition by disconnecting the branch experiencing the fault condition from the corresponding power bus.

[0040] Continuing with the general system referenced above, Figure 1 An embodiment of a motor vehicle 10 is shown that includes a battery system controller 24 configured to control a battery system. The vehicle 10 includes a vehicle body 12 that at least partially defines a passenger compartment 14. The vehicle body 12 also supports various vehicle subsystems, including a propulsion system 16, a battery system 22, other subsystems for supporting the functions of the propulsion system 16 and other vehicle components, such as a braking subsystem, a suspension system, a steering subsystem, a fuel injection subsystem, an exhaust subsystem, etc.

[0041] The vehicle 10 may be an internal combustion vehicle, an electric vehicle (EV), or a hybrid vehicle. In one embodiment, the vehicle 10 is a hybrid vehicle that includes an internal combustion engine system 18 and at least one electric motor assembly. For example, the propulsion system 16 includes a first electric motor 20 and a second electric motor 21. The electric motors 20 and 21 may be configured to drive wheels (not shown) on opposite sides of the vehicle 10. Any number of electric motors positioned at various additional locations around the vehicle 10 may be used to provide power to corresponding systems and subsystems.

[0042] The battery system 22 can be electrically connected to the motors 20 and 21 and / or other components, such as vehicle electronics. The battery system 22 can be configured as a rechargeable energy storage system (RESS) and include a plurality of power battery cells divided into a plurality of sections. The battery system controller 24 is included in the battery system 22 and controls the charging and discharging functions of the batteries within the battery system 22. In an alternative configuration, the battery system controller 24 can be a universal vehicle controller that is remote from the battery system 22 and configured to control a plurality of systems and / or subsystems. The universal vehicle controller can be located anywhere within the vehicle 10. In another alternative, the battery system controller 24 can be a distributed control system that includes a plurality of coordinated controllers throughout the vehicle 10, including controllers within the battery system 22 and controllers remote from the battery system 22.

[0043] In one embodiment, the battery system 22 includes one or more battery packs 28. The battery pack 28 includes a plurality of different battery power cells arranged in parallel and connected to a power distribution bus 29 for providing power to one or more systems. Figure 1 In the exemplary system of , the power distribution bus 29 is shown in simplified form as a single line and provides power to the propulsion system 16 through the inverter 32 .

[0044] Continue to refer Figure 1 , Figure 2 A general block diagram of the battery system 22 including a first battery pack 102 and a second battery pack 104 is shown. Figure 3 and Figure 4 Shows Figure 2 1. A first battery pack 102 and a second battery pack 104 are connected in parallel and via a multilevel inverter 110. The multilevel inverter 110 is connected to each inverter branch of the motors 20, 21 and provides operating AC power to the motors 20, 21 from the positive bus 130 during standard operation. In addition to the DC-DC converter 110, a load 120 may be connected across the positive bus 130 and the neutral bus 132 to receive power from the battery packs 102, 104. In some examples, such as Figure 2 The examples shown and Figure 3 In the specific example of , the motors 20, 21 have a Y-branch configuration (alternatively referred to as a four-terminal motor) in which the neutral node 103 is connected to the positive bus 130 via a connection 134. In other examples, for example Figure 4In a specific example of, the motors 20, 21 have a delta-branch configuration (alternatively referred to as a three-terminal motor) with a floating neutral point (i.e., there is no internal connection of the motor branches to a neutral or reference voltage). The battery system 22 can be connected to a charger 140, such as a wall charger, and the charger 140 allows power to be provided to the battery system 22 to charge the battery packs 102, 104.

[0045] The battery system 22 includes mixed chemistry battery packs 102, 104, which may include a mix of fuel cell units, lithium (Li) ion packs, and any similar battery types. Each battery pack 102, 104 includes a single chemistry, and the chemistry of each battery pack 102, 104 is different from the chemistry within the other battery packs 102, 104. The mixed chemistry provides different power characteristics for the battery packs 102, 104, with some battery packs 102, 104 having faster charging rates and lower power density, while other battery packs 102, 104 have slower charging rates and higher power density. Due to the varying charging rates and power densities, passive balancing by placing battery packs in parallel with filtering inductors, as done in existing battery systems, cannot properly redistribute power from one battery pack to another.

[0046] In order to properly balance the battery packs 102, 104 during charging and / or immediately after charging is completed, the battery system 22 includes a battery system controller 150. In some examples, Figure 1 The battery system controller 24 may provide the functionality of the battery system controller 150, and in other embodiments, the functionality is provided by a dedicated controller 150 distributed across multiple vehicle controllers or any similar control scheme. It should be understood that references to the controller 150 herein encompass a variety of controller types and configurations and are not limited to the dedicated battery system controller 150 shown.

[0047] During charging, or immediately after charging, the battery packs 102, 104 may be unbalanced, or one battery pack may charge faster than the other. When this happens, it is desirable to transfer power from one battery pack 102, 104 to the other battery pack 102, 104. Since the process described herein utilizes the motor 20, 21 in a non-rotational capacity, it may not be suitable for use during vehicle operation depending on the function of the motor. Since the battery packs 102, 104 are different chemistries with different power densities and charging characteristics, a DC-DC converter is required to transfer power from one battery pack 102, 104 to another battery pack 102, 104. The controller 150 is configured to utilize a switch that connects the charger 140 to the battery packs 102, 104, operate the inverter 110 in a DC-DC converter mode, and utilize the inherent inductance of the motor branch in the motor 132 to transfer power from one battery pack 102, 104 to another battery pack 102, 104 without generating rotational motion in the motor.

[0048] Power is passed through each motor branch by modulating the switching of each inverter branch so that the switching in the branch is offset 180 degrees from the other two branches. This allows the inductance of each motor branch to operate as a DC-DC converter inductor for the corresponding inverter branch of the AC inverter 110. Modulation of the switches in each inverter branch of the AC inverter 110 occurs in accordance with known techniques to achieve DC-DC converter operation.

[0049] Continue to refer Figure 2 , Figure 3 Shows Figure 2 A more detailed example implementation of an electric power system of FIG. The motors 20 , 21 are arranged in a Y-shaped configuration (alternatively referred to as four-terminal motors 20 , 21 ). Each motor branch of the motors 20 , 21 is shown as an inductor 302 , 304 , 306 , which represents the internal inductance of that motor branch of the motors 20 , 21 . The charger 140 is connected to the first battery pack 102 via a first pair of switches 310 , 312 , and to the second battery pack 104 via a second pair of switches 314 , 316 . One switch 310 , 314 in each pair of switches connects the positive terminal of the charger 140 to the corresponding battery pack 102 , 104 , and the second switch 312 , 316 connects the negative terminal of the charger 140 to the corresponding battery pack 102 , 104 .

[0050] Additionally, the first battery pack 102 is connected to the positive bus 132 via switch 320 and to the negative bus 134 via switch 322. The second battery pack 104 includes a connection to the positive bus 130 via switches 310, 314, 320, and switch 324 connects the positive side of the second battery pack 104 to the motor neutral point 133 via the neutral node 103. The negative side of the second battery pack 104 is connected to the negative bus 132 via switch 324.

[0051] The AC inverter 110 is arranged in a multi-level T-type inverter topology including three inverter branches 330, 340, 350. Each inverter branch 30, 340, 350 has a first transistor X1, X5, X9 connecting the positive node 331, 341, 351 to the AC output node 332, 342, 352, a second transistor X2, X6, X10 connecting the AC output node 332, 342, 352 to a low node 333, 343, 353, and a pair of third and fourth transistors X3, X4, X7, X8, X11, X12 connecting the AC output node 332, 342, 352 to the midpoint 331 of the DC link. For clarity, in Figure 3 The logo is omitted afterwards Figure 3 and Figure 4 The inverter branches 330, 340, 350 and Figure 5 and Figure 6 Certain reference numerals of elements of the corresponding inverter branches 530, 540, 550. Figure 4 , Figure 5 and Figure 6 The absence of a specific reference numeral in the text should not be interpreted as indicating the absence of an element, but rather as indicating that the element is in close proximity. Figure 3 in the same position.

[0052] The AC output node 332, 342, 352 of each inverter branch 330, 340, 350 is connected to the corresponding motor branch 302, 304, 306 of the motor 20, 21. During typical operation, the controller 150 modulates the transistors X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12 within each inverter branch 330, 340, 350 of the AC inverter 110 to drive the motor 20, 21 using either of the battery packs 102, 104 connected to the positive bus 130 and the negative bus 132. A pair of capacitors 370 are connected in parallel to the branches 330, 340, 350 of the inverter.

[0053] During or shortly after charging, it may be desirable to balance power between the battery packs 102, 104 or to transfer power from one of the battery packs 102 to the other battery pack 104. As an example, when the first battery pack has a low power density but a high charge rate, it may be beneficial to transfer the accumulated power from the faster charging battery pack 102 to the slower charging battery pack 104 in order to speed up the overall charging process.

[0054] Balancing and power transfer are achieved by modulating the transistors X1, X2, X3, XC4, X5, X6, X7, X8, X9, X10, X11, X12 in the AC inverter 110, thereby using the internal inductance of the motor branches 302, 304, 306 as the corresponding DC-DC converter inductors, so that the AC inverter operates as a DC-DC inverter. In this mode, each of the switches 310, 312, 314, 316 connecting the battery packs 102, 104 to the charger 140 is open, and the switches 320, 322, 324, 326 connecting the two battery packs to the positive bus 130 and the negative bus 132 are closed. Each inverter branch 330 , 340 , 350 is modulated at a phase offset of 120 degrees from each other inverter branch 330 , 340 , 350 , allowing power to pass through the motors 20 , 21 while producing a net zero rotational force and enabling the inductance of the motor branches 302 , 304 , 306 to be utilized.

[0055] In this configuration, energy circulates through the motor branches 302, 304, 306 and the corresponding inverter branches 330, 340, 350. The inverter branches 330, 340, 350 convert the DC power to voltage and current levels that can be accepted by the receiving battery pack 102, 104. The power with the new characteristics is provided to the power bus 130, 132, allowing power to be transferred from one battery pack 102, 104 to another battery pack 102, 104.

[0056] In addition, since each battery pack 102, 104 is connected to the power bus 130, 132 and the charger 140 via switches 320, 322, 326, 328, the controller 150 can isolate or remove a single battery pack 102, 104 when one of the battery packs 102, 104 is in a faulty state. In order to isolate the faulty battery pack 102, 104, the corresponding switch 320, 322, 326, 328 connecting the battery pack 102, 104 to the bus 130, 132 remains open, resulting in the battery packs 102, 104 being electrically isolated.

[0057] refer to Figure 4 , when the motors 20, 21 are configured in a delta configuration, there is no neutral point within the motors 20, 21 to which the switch 326 can be connected. Figure 4 As shown in Figure 2 and Figure 3 The same reference numerals denote the same elements and configurations. Figure 4 Examples with Figure 3 The example of is different only in that the switch 326 is connected to the neutral point 352 of one of the inverter branches 350 of the AC inverter 110 .

[0058] When operating in the DC-DC converter mode, the transistors X9, X10, X11, X12 within the inverter branch 350 remain disconnected, and the inverter 110 operates as a two-phase DC-DC converter, wherein the other two inverter branches 330, 340 are modulated to be 180 degrees offset from each other. When in this mode, power passes through the motor branch 306 corresponding to the inverter branch 350 that is turned off, resulting in power passing through the motor branch 306 and each other inverter branch 330, 340, because the inverter branches 330, 340 are modulated to produce DC power with appropriate power characteristics. In this mode, power from the second battery pack 120 passes through the switch 326 and flows through the third motor branch 306 of the motor 20, 21 into each of the other motor branches 302, 304 of the motor 20, 21. Energy passes through the inverter branches 330, 340 and is provided to the first battery pack 102.

[0059] In the example of a delta configuration motor, in some examples, it is beneficial to ensure that the motor branch that is not operated during DC-DC motoring is the motor branch that is physically closest to the battery packs 402, 404 arranged in series. In some configurations, this motor branch is between the battery packs 402, 404 and other motor branches arranged in series. Utilizing the motor branch that is physically closest to the battery packs 402, 404 provides thermal separation between the battery packs 402, 404 and the operating motor branches, thereby minimizing the chance of excessive heating.

[0060] In some cases, different chemical battery packs can be arranged in series between the positive bus and the negative bus. Such an example is Figure 5 and Figure 6 It is shown in Figure 5 The connected Y-shaped motors 20, 21 are shown, and Figure 6 The connected delta-shaped motors 20 , 21 are shown. Figure 5 and Figure 6 The inverter branches 530, 540, 550 shown in FIG. Figure 3 and Figure 4 The inverter branches shown in FIG. 1 are arranged identically.

[0061] Specific reference Figure 5, the two battery packs 102, 104 are connected in series across the positive bus 130 and the negative bus 132, wherein the positive terminal of the second battery pack 104 is connected to the negative terminal of the first battery pack 102 at the battery pack connection node 592. The battery pack node 592 is connected to the neutral node 103 of the motor 20, 21 via a switch 594. When the inverter branches 530, 540, 550 are driven in the DC-DC converter mode, the switch 594 is closed, which creates a current circulation path between the battery packs 102, 104, wherein each motor branch 502, 504, 506 of the motor 20, 21 provides an internal branch inductance, and the switches of the corresponding inverter branches 530, 540, 550 (wherein the motor branch 502 corresponds to the inverter branch 530, the motor branch 504 corresponds to the inverter branch 540, and the motor branch 50 corresponds to the inverter branch 550) are modulated to be 120 degrees offset from each other inverter branch 530, 540, 550. In this mode, the current circulation between the battery packs 102, 104 balances the charge in each battery pack 102, 104, and this mode can be used during or after the series charging of the battery packs 102, 104.

[0062] Continue to refer Figure 1-5 , Figure 6 The battery packs 102, 104 connected in series are schematically shown, wherein the motors 20, 21 have a delta configuration rather than a wye configuration. In the delta configuration, the battery pack node 592 is connected to one of the motor branches 502. When the switch 594 is closed and the switches in the branches 530, 540, 550 of each inverter 110 operate as a DC-DC converter, the switch 594 creates a current circulation path from the second battery pack 104 through the first motor branch 502 and into each of the second motor branch 504 and the third motor branch 506, and then returns to the first battery pack 102. Each of the second motor branch 504 and the third motor branch 506 is modulated to have a phase shift that is offset by 180 degrees from the other motor branch 504, 506 to ensure that the motors 20, 21 do not rotate. When the switch 594 is closed (allowing current to pass), the charge level between the two battery packs 102, 104 is equalized.

[0063] In each of the above examples, different chemical battery packs 102, 104 are shown as single battery packs. It should be understood that each single battery pack 102, 104 can be replaced with a group of sub-batteries arranged in series, as long as each sub-battery arranged in series includes the same chemical composition as each other sub-battery arranged in series in the battery packs 102, 104. In some cases, the sub-batteries can have the same storage capacity. In other examples, the sub-batteries can have different storage capacities. In any configuration, the total capacity of the battery packs 102, 104 is the sum of the capacities of the sub-batteries.

[0064] The following are for Y-type / four-terminal motors 20, 21 ( Figure 3 and Figure 5 )'s specific example control scheme.

[0065] Continue to refer to Figure 3 and Figure 5 (four terminal motors 20, 21), controlling the multilevel inverter 110 as a DC-DC converter includes providing a first control signal to a first transistor X1, X5, X9 and a second transistor X2, X6, X10 of each inverter branch 330, 530, 340, 540, 350, 550, wherein the first control signal is inverted for the first transistor X1, X5, X9. A second control signal is provided to a third transistor X3, X7, X11 and a fourth transistor X4, X8, X12, wherein the second control signal is inverted for the third transistor X3, X7, X11 of each inverter branch 330, 530, 340, 540, 350, 550. The first control signal is modulated using pulse width modulation to achieve a DC-DC converter operation using the first and second transistors X1, X2, X5, X6, X9, X10 and each inverter branch 330, 530, 340, 540, 350, 550 is phase shifted by 120 degrees from each other inverter branch 330, 530, 340, 540, 350, 550. The modulation of the first control signal and the second control signal is done according to a typical three-phase DC-DC converter operation.

[0066] The following are delta / three-terminal motors 20, 21 ( Figure 4 and Figure 6 )'s specific example control scheme.

[0067] Continue to refer to Figure 4 and Figure 6, (three-terminal motor 20, 21) controlling the multilevel inverter 110 as a DC-DC converter includes: for each of the first inverter branch 340, 530 and the second inverter branch 350, 550, providing a first control signal to the first transistor X1, X5 and the second transistor X2, X6 of each of the first and second inverter branches 340, 540, 350, 550, wherein the first control signal is inverted for the second transistor X2, X6. A second control signal is provided to the third transistor X7, X11 and the fourth transistor X8, X12 of the first and second inverter branches 240, 350, 530, 550, wherein the second control signal is inverted for the fourth transistor X8, X12 of each of the first and second inverter branches 340, 540, 350, 550. The first control signal and the second control signal control the open / closed state of the first, second, third and fourth transistors X5, X6, X7, X8, X9, X10, X11, X12 of the corresponding inverter branch 304, 504 via pulse width modulation (PWM). The modulation of the control signal for each of the first and second branch inverters 340, 540, 350, 550 is phase-shifted by 180 degrees from the other inverter branch 340, 540, 350, 550.

[0068] Additionally, in the three-terminal example, a third control signal is provided to the first, second, third and fourth transistors X1, X2, X3, X4 of the third inverter branch 530. The third control signal sets the first, second, third and fourth transistors X1, X2, X3, X4 to off for the duration of controlling the multilevel inverter as a DC-DC converter.

[0069] Figure 2-6 The system shows an apparatus and method that uses a multi-level T-type inverter drive system as a DC-DC converter (using a non-rotating motor and a multi-level inverter during steady drive, or using any non-rotating motor and a multi-level inverter during stationary conditions) to provide bidirectional power transmission between hybrid chemical battery packs 102, 104 (e.g., a mix of energy and power packs / modules, fuel cells, and lithium battery packs). When operating as a DC-DC converter, the machine winding inductance of each motor branch 302, 304, 306, 502, 504, 506 of the non-rotating motor 20, 21 and the corresponding inverter branch 330, 340, 350, 530, 540, 550 acts as a synchronous or interleaved two-phase multi-level boost converter (DC-DC converter), where the winding inductance of the third motor branch provides additional boost and filtering action.

[0070] As used herein, “first,” “second,” and “third” inverter legs are arbitrary designators used to distinguish the operation of inverter legs 330 , 340 , 35 , 530 , 540 , 550 , and do not imply any unstated position or operating parameter.

[0071] The new control scheme is incorporated into the controller (150, see Figure 2 ) for operating a multilevel inverter in DC-DC mode. The control scheme controls the on / off state to control the power flow in either direction through the non-rotating motor and the multilevel inverter. The charging port can be used to charge the battery pack continuously, and the DC-DC converter mode can be used to charge the first battery pack from the charging port and the second battery pack from the first battery pack using the DC-DC mode of the multilevel inverter motor system. In some examples, the switches in the multilevel inverter are insulated gate bipolar transistors or Si / SiC / GaN field effect transistors with anti-parallel diodes. In some examples, the new control scheme is completely software-based and can be retroactively added to existing controllers and applied to existing motor vehicles without replacing or reconfiguring components. In some examples, certain switches X3, X4, X7, X8, X11, X12 for each inverter branch can be replaced by reverse blocking anti-series IGBs or MOSFETS and appropriately controlled. These switches X3, X4, X7, X8, X11, X12 can be alternatively referred to as auxiliary switches.

[0072] The charge balancing or power transfer configuration can be used for single-port or multi-port charging events. All (in the case of a four-terminal motor) or selected (in the case of a three-terminal motor) phases are modulated using logic with a predetermined phase shift relative to each other (e.g., 180 degrees for a four-terminal motor or 120 degrees for a three-terminal motor). The phase shift is achieved by pulse width modulation (PWM) control of the internal switches. The duty cycle and phase relationship between the internal switches are selected to achieve the boost or buck function of the DC-DC converter, and the power flow is in the desired direction (e.g., from the first battery pack to the second battery pack) while avoiding shorting the main bus. The PWM frequency, duty cycle, and phase shift between the switching inverter branches are functions of the charging power and current ripple to be achieved during the charging operation and can be determined by a person skilled in the art.

[0073] In a battery pack having a series arrangement (e.g., Figure 5 and Figure 6), the multi-level T-type inverter 110 and the corresponding motor windings 502, 504, 506 of the motors 20, 21 are used to actively balance the state of charge of the two battery packs 102, 104 during or after series charging. The second battery pack 102 is continuously charged until the difference in the state of charge of the two battery packs 102, 104 is less than a predetermined threshold. The four-terminal machine example uses a switch to connect the midpoint of the battery pack and the neutral point of the four-terminal winding machine. The three-terminal machine example uses a switch to connect the midpoint of the battery pack and one branch terminal of the three-terminal machine.

[0074] In one variation of a three-terminal motor, the inactive inverter branches of the inverter 110 may be switched out of circuit using dedicated switches, rather than controlling transistors within the inactive inverter branches to remain off.

[0075] Figure 8 An example of this is shown, and Figure 7 It shows that it can be Figure 8 An example capacitor mounting configuration is shown for use in one embodiment of the variation. Structurally, Figure 8 Examples with Figure 4 The example differs in that the positive DC bus 130 and the negative DC bus 132 include a switch connection 670 (shown via sub-schematic diagram 680) that is configured to disconnect one of the inverter branches 620, 630, 640 (620 in the illustrated configuration) from the positive DC bus 130 using a first switch 672 for the duration of operation as a DC-DC converter.

[0076] During the duration of operation as a DC-DC converter, the second switch 674 disconnects the return node 660 of the inverter branch 620 from the return node 660 of each of the other inverter branches 640, 650. The first switch 672 and the second switch 674 can receive the same control signal and will always be in the same state. In addition, the third switch 676 connects the return node 660 of the inverter branch 630 to the positive terminal of the battery 102 during the duration of operation as a DC-DC converter. This switch arrangement allows power to flow from the battery 102 through the first inverter branch 630 to the motor inductor 602 corresponding to the first inverter branch 630, and then through the motor to the other two inverter branches 640, 650 operating as DC-DC converters.

[0077] and Figure 4 and Figure 6As in the example of , the inverter 110 operates as a two-phase DC-DC converter, where the other two inverter branches 530, 540 are modulated to be 180 degrees apart. In this mode, the second and third inverter branches 540, 550 are modulated to generate DC power with appropriate power characteristics. Figure 7 700 is shown in FIG. 700 , where six capacitors 702 are mounted to three parallel busbar plates 704 , 706 , 708 . Figure 7 The capacitor mounting configuration minimizes loop inductance and improves performance when operating in DC-DC converter mode.

[0078] In some examples, multiple multi-level inverter units can be used to share power being transmitted to another group. In addition, N-level inverters can be used to further reduce voltage and thermal stress in dc-dc operation. The control scheme for this function includes continuous battery SOC and energy monitoring for shutting down the charging current and commanding the contactor / switch to close. The high-voltage line can have additional voltage and / or current sensors / thermal fuses for diagnostics and safety of the high-voltage line. The main contactor associated with each group can also include a pre-charging device in parallel with one main contactor.

[0079] The term "one" does not indicate a limitation of quantity, but rather indicates the presence of at least one of the referenced items. 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.

[0080] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or 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.

[0081] 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, the filing date of the earliest priority application in which the test standards appear.

[0082] 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.

[0083] 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 equivalents may be substituted for its elements without departing from its scope. 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 vehicle system, comprising: a first battery group connected to a second battery group via a T-type multilevel inverter having a plurality of inverter branches, wherein each inverter branch is arranged in a T-type topology; an electric motor connected to the T-type multilevel inverter; A controller is connected to the motor and the T-type multilevel inverter, the controller including a memory storing instructions, the instructions being configured to cause the controller to control the T-type multilevel inverter as a DC-DC converter so that a circulating current passes through the motor, the first battery pack, and the second battery pack.

2. The vehicle system according to claim 1, wherein: Each inverter branch of the T-type multilevel inverter includes: a first transistor connecting a positive node to a corresponding AC output node, a second transistor connecting the corresponding AC output node to a low node, a pair of third and fourth transistors connecting the corresponding AC output node to a midpoint of a pair of DC link capacitors; and Wherein, each phase of the motor is connected to a corresponding branch of the T-type multilevel inverter.

3. The vehicle system according to claim 2, wherein: The electric motor is a four-terminal electric motor, and wherein controlling the T-type multilevel inverter as a DC-DC converter comprises: providing a first control signal to the first transistor and the second transistor of each inverter branch, wherein the first control signal is inverted for the second transistor of each inverter branch; providing a second control signal to the third transistor and the fourth transistor of each inverter leg, wherein the second control signal is inverted for the fourth transistor; and The first control signal is modulated using pulse width modulation (PWM) of a three-phase DC-DC converter, wherein the PWM of each inverter branch is 120 degrees phase-shifted from every other inverter branch.

4. The vehicle system according to claim 2, wherein: The electric motor is a three-terminal electric motor, and wherein controlling the multilevel inverter as a DC-DC converter comprises: for each of a first inverter branch and a second inverter branch, providing a first control signal to the first transistor and the second transistor of each of the first inverter branch and the second inverter branch, wherein the first control signal inverts the first transistor of each inverter branch; providing a second control signal to the third transistor and the fourth transistor of the first inverter branch and the second inverter branch, wherein the second control signal inverts the third transistor of each of the first inverter branch and the second inverter branch; wherein the first control signal and the second control signal control the open / closed states of the first transistor, the second transistor, the third transistor, and the fourth transistor of the corresponding phase via pulse width modulation (PWM); wherein the modulated first control signal and the modulated second control signal in each inverter branch are phase-shifted by 180 degrees from the first modulated control signal and the second modulated control signal in another branch; wherein a third control signal is provided to the first transistor, the second transistor, the third transistor and the fourth transistor of a third inverter branch, the third control signal setting the first transistor, the second transistor, the third transistor and the fourth transistor to be turned off for the duration of controlling the T-type multilevel inverter as the DC-DC converter, wherein the third inverter branch is connected to the positive terminal of the first battery group.

5. The vehicle system according to claim 1, wherein: The first battery group and the second battery group are connected in parallel at one or both of a negative battery terminal and a positive battery terminal.

6. The vehicle system according to claim 1, wherein: The first battery group and the second battery group are connected in series via a common node. 7 . The vehicle system of claim 6 , wherein a neutral node connecting each phase of the electric motor is connected to a common node of the first battery pack and the second battery pack.

8. The vehicle system according to claim 6, wherein: The phase terminals of the motor are connected to a common node of the series-connected battery packs, and wherein the motor is a three-terminal motor, and a first inverter branch is physically disposed closer to the first battery pack and closer to the second battery pack than each of a second inverter branch and a third inverter branch, and wherein, during operation of the DC-DC converter, the first inverter branch is connected to the positive terminal of the battery pack.

9. The vehicle of claim 2, wherein the motor is a three-terminal motor, and wherein a first of the plurality of inverter branches is connected to a positive DC bus via a first switch, a neutral return node of the first inverter branch is connected to neutral via a second switch, and is connected to a positive terminal of the first battery pack via a third switch.

10. The vehicle system of claim 2, wherein the first battery pack includes at least a first group of power battery cells and a second group of power battery cells connected to the first group of power battery cells at the low node.

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