Modular multi-port AC battery power converter system and method of use - Patents.com

Abstract

An exemplary embodiment of the present disclosure provides a power conversion system including a first battery module, a second battery module, a first transformer, a second transformer, a first current source converter bridge, a second current source converter bridge, and a third current source converter bridge. The first and second transformers can have a low voltage side and a high voltage side. The first bridge can be configured to connect the first and second battery modules to the low voltage sides of the first and second transformers. A midpoint of the series connection of the first and second battery modules can be connected to a midpoint of the series connection of the first and second transformers. The second bridge is configured to be connectable to the high voltage side of the first transformer and one or more ports configured to transmit and / or receive power to an electrical load and / or a power source. The third bridge can be configured to connect to the high voltage side and one and more ports of the second transformer.

Description

[Technical field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 170,790, filed April 5, 2021, which is incorporated by reference herein as if set forth in its entirety.

[0002] FIELD OF THEINVENTION Various embodiments of the present disclosure relate generally to power converter systems, and more particularly to a modular multi-port AC battery power converter system with integrated low voltage batteries and improved safety against touch voltage conditions. [Background technology]

[0003] Battery-powered transportation, from bicycles to cars, trucks, and airplanes, with power ratings ranging from a few hundred watts to over 20 MW, is a key driver in the drive to decarbonize the energy infrastructure. A typical battery pack consists of an array of 4-volt Li-ion cells connected in parallel, which are then connected in series to obtain the desired battery pack voltage, ranging from 400 volts to over 1000 volts. Given the history of battery fires and the significant safety issues associated with batteries, the industry has placed a strong focus on safety, including electrical, mechanical, and thermal management, and rigorous testing, including crash and rollover tests. As the number of electric vehicles (EVs) on the road increases, more people will be involved in accidents, some of which are severe and occur under harsh environmental conditions. Compared to gasoline-powered vehicles, the most troubling new safety concern in EVs is the high-voltage battery system, which increases the mortality rate of occupants, bystanders, and first responders. The automotive industry's response has included improving the mechanical and structural integrity of the integrated battery pack and equipping the battery pack with explosive pyrofuses that disconnect the battery terminals upon impact. However, in the event of an accident in which the battery is damaged, exposure to lethal voltages still exists. Furthermore, the trend to increase system voltages has raised concerns among organizations such as the National Fire Protection Association (NFPA) and the National Highway Traffic Safety Administration (NHTSA). It is important that the EV industry address these concerns before they become a major public concern or liability issue, or stall future EV market growth.

[0004] This problem has also been recognized in the automotive and telecommunications industries, leading to the development of 48-volt DC systems that are considered inherently touch-safe, with no harmful touch potentials present anywhere in the system. 48-volt DC systems are used in the automotive industry for mild hybridization applications to meet fuel economy standards, and more recently in small EVs. While the inherent safety of 48-volt DC systems is well understood, scaling their capabilities to the required power levels has been challenging with currently available technology. This has led to the development of high-voltage battery packs that employ sophisticated techniques for protection, dielectric isolation, and thermal management, with thousands of cells distributed across the length and width of the vehicle, with complex Battery Management Systems (BMS) for control at the cell level. These developments have had a significant impact on battery life, performance, and the integration and matching of rapidly evolving battery technologies. These constraints are in addition to the safety issues discussed above.

[0005] The battery pack also dictates everything else that goes on board the vehicle. For example, a typical car may have one 120 kW inverter that drives a motor to propel the car, as shown in FIG. 1. This inverter drive runs off of a high voltage battery and typically relies on a two-level voltage source inverter (VSI) architecture, as shown in FIG. 2. An AC / DC isolation converter is also installed on the vehicle to allow direct connection to 208 VAC to 240 VAC for Level 2 charging. Fast charging of electric vehicles is also a key feature for fleet charging and addressing range anxiety, with charging rates of 50 kW to 300 kW for cars to date and up to 2 MW for trucks. The infrastructure for commonly used DC fast charging is expensive, with total costs expected to exceed $50 billion in the United States alone. Such infrastructure is being adopted because putting high power DC chargers on vehicles has been deemed impractical due to size and cost. Even with fast charging capabilities, there are significant limitations. With many cells connected in series in a battery pack, it is paramount that each cell is charged evenly, which requires complex BMS systems and requires that the charging current of the entire stack be reduced early in the charging cycle if the batteries are to be avoided from overcharging and catching fire. It is therefore clear that design decisions regarding the architecture of a power system, especially those that assume that the batteries must remain as one single stack, require significant compromises in the safety, cost, and performance of the overall system. Summary of the Invention

[0006] An exemplary embodiment of the present disclosure provides a power conversion system including a first battery module, a second battery module, a first transformer, a second transformer, a first current source converter bridge, a second current source converter bridge, and a third current source converter bridge. The second battery module can be connected in series with the first battery module. The first transformer can have a low voltage side and a high voltage side. The second transformer can have a low voltage side and a high voltage side, and the low voltage side of the first transformer can be connected in series with the low voltage side of the second transformer. The first current source converter bridge can be configured to connect the first battery module and the second battery module with the low voltage side of the first transformer and the second transformer, and the midpoint of the series connection of the first battery module and the second battery module can be connected to the midpoint of the series connection of the first transformer and the second transformer. The second current source converter bridge can be configured to connect to the high voltage side of the first transformer and to one or more ports configured to transmit and / or receive power to and / or from an electrical load and / or power source. The third current source converter bridge can be configured to connect to the high voltage side of the second transformer and to one or more ports configured to transmit and / or receive power to and / or from an electrical load and / or power source.

[0007] In any of the embodiments disclosed herein, the first converter bridge may include a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to terminals of a low-voltage side winding of the first transformer.

[0008] In any of the embodiments disclosed herein, the first switching circuit may include a first controllable switch connected in series with a second switch.

[0009] In any of the embodiments disclosed herein, the first controllable switch may be a Si MOSFET.

[0010] In any of the embodiments disclosed herein, the second switch may be one of a diode, a controllable switch, and a GaN HEMT.

[0011] In any of the embodiments disclosed herein, the first switching circuit may further include a resonant pole network connected in parallel with the series connected first controllable switch and second switch.

[0012] In any of the embodiments disclosed herein, the resonant pole network may be configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the first switching circuit.

[0013] In any of the embodiments disclosed herein, the resonant pole network may comprise a capacitor connected in series with a resistor-diode circuit.

[0014] In any of the embodiments disclosed herein, the resistor-diode circuit can provide different impedances during charging and discharging of the capacitor of the first resonant pole network.

[0015] In any of the embodiments disclosed herein, the first switching circuit may include a clamping device configured to transmit power from the first transformer to the second battery module.

[0016] In any of the embodiments disclosed herein, the clamping device may be one of a diode, a controllable switch, and a GaN HEMT.

[0017] In any of the embodiments disclosed herein, the first switching circuit may include a first controllable switch connected in series with the second switch, and the first switching circuit may further include a bypass capacitor connected in series with the clamping device such that the series connection of the bypass capacitor and the clamping device may be connected in parallel to the first controllable switch connected in series with the second switch.

[0018] In any of the embodiments disclosed herein, the first power converter bridge may include a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low-voltage side terminal of the second transformer.

[0019] In any of the embodiments disclosed herein, the second switching circuit may include a first controllable switch connected in series with a second switch.

[0020] In any of the embodiments disclosed herein, the first controllable switch may be a Si MOSFET.

[0021] In any of the embodiments disclosed herein, the second switch may be one of a diode, a controllable switch, and a GaN HEMT.

[0022] In any of the embodiments disclosed herein, the second switching circuit may further include a resonant pole network connected in parallel with the series connected first controllable switch and second switch.

[0023] In any of the embodiments disclosed herein, the resonant pole network may be configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the second switching circuit.

[0024] In any of the embodiments disclosed herein, the resonant pole network may comprise a capacitor connected in series with a resistor-diode circuit.

[0025] In any of the embodiments disclosed herein, a resistor-diode circuit can provide different impedances during charging and discharging of the capacitors of the resonant pole network.

[0026] In any of the embodiments disclosed herein, the second switching circuit may include a clamping device configured to transmit power from the second transformer to the first battery module.

[0027] In any of the embodiments disclosed herein, the clamping device may be one of a diode, a controllable switch, and a GaN HEMT.

[0028] In any of the embodiments disclosed herein, the second switching circuit may include a first controllable switch connected in series with the second switch, and the second switching circuit may further include a bypass capacitor connected in series with the clamping device such that the series connection of the bypass capacitor and the clamping device may be connected in parallel to the first controllable switch connected in series with the second switch.

[0029] In any of the embodiments disclosed herein, the first switching circuit may comprise a clamping device configured to transmit power from the first transformer to the second battery, the first power converter bridge may comprise a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low-voltage terminal of the second transformer, the second switching circuit may comprise a first controllable switch connected in series with a second switch, the second switching circuit may comprise a clamping device configured to transmit power from the second transformer to the first battery, the first controllable switch connected in series with the second switch of the first switching circuit may be connected in series with the clamping device of the second switching circuit, and the clamping device of the first switching circuit may be connected in series with the series connected first controllable switch and second switch of the second switching circuit.

[0030] In any of the embodiments disclosed herein, the power converter system may not include a resonant circuit connected in parallel across the low-voltage side of the first transformer and / or the second transformer.

[0031] In any of the embodiments disclosed herein, the second current source converter bridge can include a first resonant circuit connected in parallel to the high voltage side of the first transformer, and the third current source converter bridge can include a second resonant circuit connected in parallel to the high voltage side of the second transformer.

[0032] In any of the embodiments disclosed herein, at least one of the second current source converter bridge and the third current source converter bridge may include at least one reverse blocking switch.

[0033] In any of the embodiments disclosed herein, the at least one reverse blocking switch may comprise a controllable switch connected in series with a diode.

[0034] In any of the embodiments disclosed herein, the at least one reverse blocking switch may comprise a first controllable switch and a second controllable switch connected in series with opposite current blocking directions.

[0035] In any of the embodiments disclosed herein, the power conversion system may be configured such that when the first current source converter bridge, the second current source converter bridge, and the third current source converter bridge are inactive, the maximum voltage in the system is the voltage level of the first battery module or the second battery module.

[0036] In any of the embodiments disclosed herein, the voltage level of the first battery module or the second battery module may be less than 60 volts.

[0037] In any of the embodiments disclosed herein, the first current source converter bridge may be configured to operate in a switching cycle.

[0038] In any of the embodiments disclosed herein, the switching cycle may include a cross-clamp phase, in which power is transferred from at least one of the first transformer and the second transformer through at least one clamping device to at least an opposite battery pole.

[0039] In any of the embodiments disclosed herein, the first current source converter bridge may be configured such that a majority of leakage energy from at least one of the first transformer and the second transformer may be recovered in at least one of the first battery module and the second battery module.

[0040] In any of the embodiments disclosed herein, the power conversion system can be configured to operate in a fail-safe state, where all controllable power devices connected to the first current source converter bridge, the second current source converter bridge, and the third current source converter bridge are turned off, and the magnetizing current of at least one of the first transformer and the second transformer is discharged into at least one of the first battery module and the second battery module.

[0041] In any of the embodiments disclosed herein, one or more ports of the second current source converter bridge and the third current source converter bridge may include a first port connected to the first electric motor.

[0042] In any of the embodiments disclosed herein, the one or more ports of the second current source converter bridge and the third current source converter bridge may include a first port connected to the first electric motor and a second port connected to a charging terminal.

[0043] In any of the embodiments disclosed herein, the one or more ports of the second current source converter bridge and the third current source converter bridge may further include a third port connected to the second electric motor.

[0044] In any of the embodiments disclosed herein, the one or more ports of the current source converter may further comprise a second port connected to a second electric motor.

[0045] Another embodiment of the present disclosure provides a modular battery system comprising a first power conversion system and a second power conversion system that can be connected in parallel to one or more ports of the first power conversion system and the second power conversion system that are configured to transmit power to and / or receive power from an electrical load and / or a power source.

[0046] These and other aspects of the present disclosure are described in the following detailed description and the accompanying drawings. Other aspects and features of the embodiments will become apparent to those skilled in the art upon review of the following description of certain exemplary embodiments in conjunction with the drawings. Although features of the present disclosure may be discussed in connection with certain embodiments and figures, all embodiments of the present disclosure may include one or more of the features discussed herein. Furthermore, although one or more embodiments may be described as having certain advantageous features, one or more of such features may also be used with various embodiments described herein. Similarly, although exemplary embodiments may be described below as device, system, or method embodiments, it should be understood that such exemplary embodiments may be implemented in various devices, systems, and methods of the present disclosure.

[0047] The following detailed description of certain embodiments of the present disclosure will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, certain embodiments are shown in the drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 illustrates a conventional two-level voltage source inverter used in motor drive applications for electric vehicles.

[0049] [Diagram 2] FIG. 1 illustrates a conventional electric vehicle power architecture that uses a high-voltage battery pack.

[0050] [Diagram 3]FIG. 1 provides an example configuration of a power converter system that achieves two high-voltage ports (one three-phase inverter port and one three-phase AC or DC fast charging port) for electric vehicle applications from two low-voltage battery modules and uses a series connection of two controllable switches (e.g., dual MOSFET structures) for the high-voltage converter bridge in accordance with an exemplary embodiment of the present disclosure.

[0051] [Figure 4] FIG. 1 provides an example configuration of a power converter system that achieves two high-voltage ports (one three-phase inverter port and one three-phase AC or DC fast charging port) for electric vehicle applications from two low-voltage battery modules and uses a series connection of diodes and controllable switches (e.g., MOSFETs) for the high-voltage converter bridge in accordance with an example embodiment of the present disclosure.

[0052] [Diagram 5] FIG. 1 provides an example configuration of a power converter system that provides three high voltage ports (two three-phase inverter ports and one three-phase AC or DC fast charging port) for electric vehicle applications from two low voltage batteries in accordance with an example embodiment of the present disclosure.

[0053] [Figure 6] FIG. 1 provides example switching waveforms for a power converter system in accordance with an exemplary embodiment of the present disclosure.

[0054] [Figure 7] 7A-7B provide example switching transitions of controllable or active switches (Si MOSFETs) in a low voltage bridge of a power converter system according to an example embodiment of the present disclosure.

[0055] [Figure 8] FIG. 1 provides a simplified bridge control block diagram for a power converter system in accordance with an exemplary embodiment of the present disclosure.

[0056] [Figure 9] FIG. 1 provides an example electric vehicle power architecture that uses multiple modular multi-port AC battery power converter systems connected in parallel to control a single electric motor at higher power in accordance with an example embodiment of the present disclosure.

[0057] [Figure 10] FIG. 1 provides a power architecture for an example electric vehicle using multiple modular multi-port AC battery power converter systems, each controlling a dedicated electric motor, in accordance with an example embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] In order to facilitate an understanding of the principles and features of the present disclosure, various exemplary embodiments are described below. The components, steps, and materials described below as constituting various elements of the embodiments disclosed herein are intended to be illustrative and not limiting. Many suitable components, steps, and materials that perform the same or similar functions as the components, steps, and materials described herein are intended to be encompassed within the scope of the present disclosure. Such other components, steps, and materials not described herein may include, but are not limited to, similar components or steps developed after the development of the embodiments disclosed herein.

[0059] As described below, the present disclosure is directed to power converter systems. For illustrative purposes, the following embodiments are described in the context of a modular multi-port AC battery (MMACB), which can be used as a versatile building block to meet a wide variety of end-use applications that can benefit from intrinsic safety, especially in electric vehicles. The MMACB can limit the maximum voltage in the system to less than 60 volts, defined as a touch-safe or non-hazardous voltage, while the power conversion system is turned off (i.e., semiconductors are gated off), and can be scaled to hundreds of kilowatts. The MMACB can integrate the battery and all necessary power converters to form an intelligent multi-port building block. The intelligent multi-port building block (1) can manage batteries including BMS, charging, and protection, (2) can provide multiple output ports for EV traction and vehicle charging / fast charging, (3) can enable the use of multiple MMACBs to achieve advanced functions including grid support, vehicle-to-grid (V2G), and forming autonomous bottom-up microgrids, and (4) can be fully protected and safe in case of electrical failure, accident, system failure, or physical damage to the system. Additionally, the MMACB can create a technology-agnostic building block that allows unparalleled flexibility and can be interoperable with future battery and power conversion technologies.

[0060] As shown in Fig. 1, the MMACB may include a first power converter bridge 150, a second power converter bridge 155, and a third power converter bridge 160. The second power converter bridge 155 may be connected to the first power converter bridge 150 via the first transformer 125 such that the first power converter bridge 150 is connected to a low voltage side of the first transformer 125 and the second power converter bridge 155 is connected to a high voltage side of the first transformer 125. The third power converter bridge 160 may be connected to the first power converter bridge 150 via the second transformer 126 such that the first power converter bridge 150 is connected to a low voltage side of the second transformer 126 and the third power converter bridge 160 is connected to a high voltage side of the second transformer 126.

[0061] In some embodiments, the MMACB can utilize a soft switching solid state transformer (S4T) converter for the high voltage bridge and a novel CSI bridge structure for the low voltage battery bridge, as shown in FIG. 1. S4T converters are disclosed in PCT applications PCT / US2017 / 033186, PCT / US2019 / 042969, and PCT / US2021 / 038232. The MMACB can realize a multi-port converter that can manage power flow between the battery module and one or more high voltage AC and DC ports (e.g., motor, charging terminals, etc.). The multi-port converter can be fully bidirectional and can achieve high boost conversion ratios with high frequency galvanic isolation.

[0062] As shown in FIG. 1, an exemplary MMACB can incorporate two 48-volt batteries 105, 106 rated at about 15 kWh with 1C continuous discharge (15 kW) and 2C peak discharge capability (peak power of 30 kW) per module into a first power converter bridge 150. The midpoint of the battery pack is connected to chassis ground 110 with high impedance, which ensures that the touch voltage does not exceed 48 volts even under any fault or damage conditions. The converter can use a hybrid switching cell structure based on GaN HEMT and Si MOSFET for the low-voltage battery stage and a dual common source SiC MOSFET configuration for the high-voltage stage. In this form, it can operate under soft switching conditions to achieve switching frequencies above 25 kHz with efficiencies of 96.5% to 98.5% over a wide operating power range. The MMACB can feature filtered waveforms, low EMI, and coordinated control. Coordinated control allows the paralleling of modules up to hundreds of kilowatts and allows for the precise exchange of energy between ports and modules as needed every 40 microsecond converter switching cycle. Additionally, as a current-source converter, the MMACB can operate without large DC-link capacitors, is immune to shoot-through and short-circuit faults, can provide a fully protected DC port for the battery, can manage transformer leakage inductance with a lossless energy recovery mechanism, and can operate at higher temperatures than typical converters.

[0063] The high voltage bridge 155, 160 may comprise a number of inverter poles or phase legs 110A-110C, each including four controllable (also called active) switches 115A-115D connected in series. The switches 115A-115D may be any number of switches known in the art. In some embodiments, the switches 115A-115D are SiC MOSFETs (FIG. 3). In some other embodiments (as shown in FIG. 4), the switches may be a series connection of a SiC MOSFET and a SiC Schottky diode. The converter system may provide one or more ports 120A-120C to enable power transmission between a source / load and the converter system. For example, one port 120A may be used to connect an electric motor to the converter. If desired, the number of inverter poles 110A-110C can be increased to provide additional connection ports, for example for an on-board DC or AC fast charger 120B and for a second three-phase traction inverter 120C, without significantly reducing power density.

[0064] As shown in Fig. 3, the MMACB can use a split DC-link structure on the low voltage DC stage side, where a center tap point is used to connect to the midpoint of the battery pack formed by the series connection of two battery modules 105, 106. This split DC-link can be realized using two series connected high frequency transformers 125, 126, which provides this embodiment with galvanic isolation and boost conversion ratio.

[0065] Additionally, the DC-link bridge comprises two clamping devices 130, 131 that can be naturally turned on during the bridge switching transition and when all controllable power devices in this embodiment are turned off. This provides a path for the magnetizing current of the transformer to flow, enabling a lossless leakage energy recovery mechanism in this embodiment and providing a unique safety mechanism where the current DC-link is safely discharged to the battery in case of a converter fault. This cross-clamping mode of operation is unique to the proposed MMACB, which simplifies the resonant sequence on a conventional S4T-based high voltage bridge. Thus, the failure mode of the MMACB is virtually non-existent, the battery can be protected at all times, and there is little or no chance of a short circuit. In some embodiments, the cross-clamping devices 130, 131 can be implemented with GaN HEMTs to reduce conduction losses, as shown in Figures 3 and 4. In some embodiments, the cross-clamping devices 130, 131 can be implemented with diode technology that is essentially immune to reverse recovery (e.g., SiC Schottky diodes).

[0066] As shown in FIG. 3, a novel hybrid switching circuit is formed by a Si MOSFET 140, 141 and a series GaN HEMT 142, 143 (which can also be replaced by a non-reverse recovery diode technology such as SiC Schottky diode) on one first battery pole and a clamping device connected to the opposite battery pole. To enable ZVS turn-off and ZCS turn-on of the active devices (e.g., Si MOSFETs) of the low-voltage DC bridge, a resonant pole network realized by a series connection of capacitors 145, 146 and charge / discharge resistor-diode circuits 147, 148 is connected across the composite active switch circuit of the hybrid switching cell (Si MOSFET 140, 141 + GaN HEMT 142, 143). This provides a new soft switching mechanism for low-voltage DC bridge applications of MMACB without using an additional S4T resonant tank on the low-voltage bridge. This fundamental difference to the conventional S4T structure allows MMACB to scale the power range inaccessible to S4T using a low-voltage input battery.

[0067] The two high-voltage bridges of the MMACB can employ conventional S4T bridges with all main power devices having ZVS, and can be operated in an interleaved manner to further reduce the filter requirements.

[0068] Figure 6 shows example simulation waveforms of an example MMACB over a switching cycle, with the cross-clamp mode of operation highlighted. During switching transitions, the cross-clamp operation controls the device voltage stress on the low voltage bridge, clamping it to the nominal DC battery voltage (2 x 48V = 96V in this example) while the bridge is switching across 600 amps at a 30kW operating point in this example design. The cross-clamp operation provides a lossless management mechanism for the energy trapped in the transformer leakage inductance as the magnetizing current transitions from the LV bridge to the HV bridge, as highlighted in Figure 6.

[0069] This mode of operation is also enabled during a switching cycle by gating off all power devices, so that the DC-link current is discharged to the battery as shown in the figure. This not only provides an energy recovery mechanism when the converter is used to charge a battery, but also provides an inherent fallback or fail-safe feature in the event of a converter fault, allowing the DC-link current to naturally and safely discharge to 0A without leading to a catastrophic failure as occurs with conventional current source inverters.

[0070] The turn-off and turn-on transitions of one of the active Si MOSFETs in the LV bridge of the MMACB are highlighted in FIG. 6 and shown in more detail in FIG. 7A. At turn-off, the resonant pole network performs zero-voltage switching (ZVS) as seen in the switching waveforms zoomed in FIG. 7B, with virtually no switching losses (estimated to be about 72 μJ of turn-off energy) in this example at 600 A / 96 V for a commercial device. Similarly, at turn-on in FIG. 7A, the S4T operation of the high-voltage bridge discharges the resonant pole network of the switch and the Si MOSFET turns on under zero-current switching (ZCS) conditions. As highlighted in FIG. 7A, the switching losses at turn-on in this commercial MOSFET are negligible for this example at 96 V and 600 A for the device switching. This soft-switching approach, unique to the MMACB, is the key to achieving high conversion efficiency with a low-voltage bridge operating at such high current levels with the targeted low voltage levels and high power ratings.

[0071] The control of the MMACB may follow the basic principles of a form of S4T, where each LV and each HV bridge applies a series of voltage levels or active vectors, with one bridge transferring power at a time during the active phase. The active vectors are sorted from the most positive to the most negative voltages and are applied sequentially throughout the switching cycle. The general gating pattern of the LV bridge poles, and the corresponding HV bridge, are shown alongside the simulation waveforms in Figure 6. One notable deviation from typical S4T operation may be observed during the cross-clamped mode of operation, where all active devices in both the LV and HV bridges are turned off. In this case, the cross-clamping devices naturally turn on and apply a negative voltage from the opposite battery pole to drive the DC link current I Lm This allows for a significant improvement in robustness in the MMACB control, as any control error, mis-gating, gate driver failure, or device failure will not lead to uncontrolled DC-link current levels or over-voltage conditions. Furthermore, the resonant sequence control of the S4T bridge is also simplified by systematically clamping the resonant tank voltage to a known voltage level, determined by the cross-clamp mode, before turning on the resonant switch to exit the cross-clamp mode and begin the resonant phase.

[0072] A simplified general control block diagram of an LV bridge pole-HV bridge pair is shown in Figure 8. This can be implemented in a conventional DSP-FPGA control architecture. Modulation is possible through a modified CSI space vector modulation strategy with appropriate active vector ordering. Switching cycles can be configured using the selected active vector from each bridge. Finally, higher level control loops can be used to achieve the desired control actions at the port level (e.g. V, I, P, Q, etc.).

[0073] The inherently safe MMACB architecture disclosed herein can have a significant impact on battery energy storage applications, especially in transportation systems rated at hundreds of kilowatts or more. The MMACB eliminates significant safety concerns by achieving touch-safe conditions even after a major accident and after the battery stack is damaged, without impacting performance, size, or cost (scale). Multiple MMACBs can be flexibly deployed in a vehicle and can be upgraded or replaced as needed without impacting the vehicle. Vehicle design is simplified as all power / energy management functions are integrated into one flexible, modular, and scalable building block. An exemplary power architecture for an electric vehicle using four 30 kW MMACB power conversion systems connected in parallel to drive a single 120 kW electric motor is shown in FIG. 9. An exemplary power architecture for an electric vehicle using four 30 kW MMACB power conversion systems, each driving an independent 30 kW in-wheel motor, is shown in FIG. 10. In both FIG. 9 and FIG. 10, the four MMACB power conversion systems can exchange energy through parallel connections on the AC or DC charging ports. The MMACB can be easily expanded with minimal size and cost penalty, enabling multi-port functionality including dual motor control and DC or AC input charging capability. Unlike traditional EV inverters, the soft switching and filtered waveforms reduce EMI, motor losses, and bearing currents, and do not require close proximity between inverter and motor. MMACB controlled battery charging can reduce energy losses, significantly improve the miles / minute of range that can be added, and reduce total charging time. The MMACB also enables fast charging using 3-phase AC, eliminating the cost and need for expensive nationwide DC fast charging infrastructure, dramatically impacting EV adoption.Ultimately, the MMACB will provide advanced V2G, V2H and microgrid capabilities, enabling EVs to become integrated elements in the future grid ecosystem.

[0074] It is to be understood that the embodiments and claims disclosed herein are not limited in their application to the details of construction and arrangement of the components described in the description and illustrated in the drawings. Rather, the description and drawings provide examples of possible embodiments. The embodiments and claims disclosed herein are further capable of other embodiments and can be practiced and carried out in various ways. It is also to be understood that the phraseology and terminology used herein are for the purpose of description and should not be considered as limiting the scope of the claims.

[0075] As such, those skilled in the art will appreciate that the conception on which the present application and claims are based may be readily utilized as a basis for the designing of other structures, methods and systems for carrying out some of the purposes of the embodiments and claims presented herein, and it is important that the claims be regarded as including such equivalent constructions.

[0076] Moreover, the purpose of the foregoing Abstract is to enable the U.S. Patent and Trademark Office and the general public, including those skilled in the art who are not particularly familiar with patent and legal language or phraseology, to quickly determine the nature and substance of the technical disclosure of the present application upon a quick reading. The Abstract is not intended to define the scope of the claims of the present application, nor is it intended to limit the scope of the claims in any way.

Claims

1. A first current source converter bridge configured to connect a first electrical bus and a second electrical bus to a low voltage side of a first transformer and a low voltage side of a second transformer, wherein a midpoint of a series connection between the first electrical bus and the second electrical bus is connected to a midpoint of a series connection between the first transformer and the second transformer; A power conversion system comprising: a second current source converter bridge configured to connect to a high voltage side of the first transformer and to one or more ports configured to transmit power to and / or receive power from an electrical load and / or a power source.

2. The first electrical bus is an electrical load and / or a power source, or a battery module. the second electrical bus is an electrical load and / or a power source, or a battery module; or the first current source converter bridge includes a first switching circuit configured to selectively connect a first pole of the first electrical load, which is a battery module, and an opposite pole of the second electrical load, which is a battery module, to a low voltage terminal of the first transformer; The power conversion system of claim 1 , wherein the power conversion system is at least one of:

3. 3. The power conversion system of claim 2, wherein the first switching circuit comprises a first controllable switch connected in series with a second switch.

4. The power conversion system of claim 3 , wherein the first controllable switch is a Si MOSFET.

5. The power conversion system of claim 3 , wherein the second switch is selected from the group consisting of a diode, a controllable switch, and a GaN HEMT.

6. 4. The power conversion system of claim 3, wherein the first switching circuit further comprises a first resonant pole network connected in parallel with the series connected first controllable switch and second switch.

7. The power conversion system of claim 6 , wherein the first resonant pole network is configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the first switching circuit.

8. The power conversion system of claim 6 , wherein the first resonant pole network comprises a capacitor connected in series with a resistor-diode circuit.

9. The power conversion system of claim 8 , wherein the resistor-diode circuit presents different impedances during charging and discharging of the capacitor of the first resonant pole network.

10. 3. The power conversion system of claim 2, wherein the first switching circuit comprises a first clamping device configured to transmit power from the first transformer to the second electrical load, the second electrical load being a battery module.

11. The power conversion system of claim 10 , wherein the first clamping device is selected from the group consisting of a diode, a controllable switch, and a GaN HEMT.

12. The first switching circuit includes: a first controllable switch connected in series with a second switch; a bypass capacitor connected in series with the first clamping device; 11. The power conversion system of claim 10, wherein the series connection of the bypass capacitor and the first clamping device is connected in parallel with the first controllable switch, which is connected in series with the second switch.

13. The first electrical load being a battery module; the second electrical load being a battery module connected in series with the first battery module; a first transformer having a low voltage side and a high voltage side; a second transformer having a low voltage side and a high voltage side; a third current source converter bridge configured to connect to a high voltage side of the second transformer and to one or more ports configured to deliver and / or receive power to an electrical load and / or a power source; a low voltage side of the first transformer is connected in series with a low voltage side of the second transformer; 2. The power conversion system of claim 1, wherein the first galvanic converter bridge comprises a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low voltage side terminal of the first transformer.

14. 14. The power conversion system of claim 13, wherein the first galvanic converter bridge further comprises a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage side terminal of the second transformer.

15. 14. The power conversion system of claim 13, wherein the second switching circuit comprises a first controllable switch connected in series with a second switch.

16. The power conversion system of claim 14 , wherein the first controllable switch is a Si MOSFET.

17. The power conversion system of claim 14 , wherein the second switch is selected from the group consisting of a diode, a controllable switch, and a GaN HEMT.

18. 15. The power conversion system of claim 14, wherein the second switching circuit further comprises a second resonant pole network connected in parallel with the series connected first controllable switch and second switch.

19. 20. The power conversion system of claim 17, wherein the second resonant pole network is configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the second switching circuit.

20. The power conversion system of claim 17 , wherein the second resonant pole network comprises a capacitor connected in series with a resistor-diode circuit.

21. A first battery module; a second battery module connected to the first battery module; a first transformer having a low voltage side and a high voltage side; a second transformer having a low voltage side and a high voltage side, the low voltage side of the first transformer being connected to the low voltage side of the second transformer; a first current source converter bridge configured to connect the first battery module and the second battery module to a low voltage side of the first transformer and the second transformer; a second current source converter bridge configured to connect to a high voltage side of the first transformer and to one or more ports configured to deliver power to and / or receive power from an electrical load and / or a power source; a third current source converter bridge configured to connect to a high voltage side of the second transformer and to one or more ports configured to deliver and / or receive power to an electrical load and / or a power source; A power conversion system, wherein a midpoint of a connection between the first battery module and the second battery module is connected to a midpoint of a connection between the first transformer and the second transformer.

22. The second battery module is connected in series to the first battery module. The low voltage side of the first transformer is connected in series with the low voltage side of the second transformer. the first galvanic converter bridge includes a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low-voltage terminal of the first transformer; the first current source converter bridge comprises a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage terminal of the second transformer; or the first current source converter bridge includes a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low-voltage terminal of the second transformer, the second switching circuit including a second clamping device configured to transmit power from the second transformer to the first battery module; 22. The power conversion system of claim 21, wherein the power conversion system is at least one of:

23. 23. The power conversion system of claim 22, wherein the second clamping device is selected from the group consisting of a diode, a controllable switch, and a GaN HEMT.

24. The first current source converter bridge includes a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage side terminal of the second transformer; The second switching circuit includes: a first controllable switch connected in series with a second switch; a second clamping device configured to transmit power from the second transformer to the first battery module; 22. The power conversion system of claim 21 comprising: a bypass capacitor connected in series with the second clamping device such that the series connection of the bypass capacitor and the second clamping device is connected in parallel with the first controllable switch which is connected in series with the second switch.

25. The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; The first switching circuit includes: a first controllable switch connected in series with a second switch; a first clamping device configured to transmit power from the first transformer to the second battery module; the first current source converter bridge includes a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage terminal of the second transformer; The second switching circuit includes: a first controllable switch connected in series with a second switch; a second clamping device configured to transmit power from the second transformer to the first battery module; the first controllable switch connected in series with the second switch of the first switching circuit is connected in series with the second clamping device of the second switching circuit; 22. The power conversion system of claim 21 , wherein the first clamping device of the first switching circuit is connected in series with the series connected first controllable switch and second switch of the second switching circuit.

26. The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; 22. The power conversion system of claim 21, wherein the power conversion system is free of a resonant circuit connected in parallel across a low voltage side of one or more transformers selected from the group consisting of the first transformer, the second transformer, and both the first transformer and the second transformer.

27. ​​The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; the second current source converter bridge includes a first resonant circuit connected in parallel with a high voltage side of the first transformer; 22. The power conversion system of claim 21, wherein the third current source converter bridge comprises a second resonant circuit connected in parallel with a high voltage side of the second transformer.

28. The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; 22. The power conversion system of claim 21, wherein at least one of the second current source converter bridge and the third current source converter bridge comprises at least one reverse blocking switch.

29. At least one reverse blocking switch comprises a controllable switch connected in series with a diode; or The at least one reverse blocking switch comprises a first controllable switch and a second controllable switch connected in series with opposite current blocking directions.

30. The power conversion system of claim 28, wherein the power conversion system is at least one of:

30. The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; 22. The power conversion system of claim 21, wherein the power conversion system is configured such that when the first current source converter bridge, the second current source converter bridge, and the third current source converter bridge are inactive, a maximum voltage of the system is a voltage level of the first battery module or the second battery module.

31. 31. The power conversion system of claim 30, wherein a voltage level of the first battery module or the second battery module is less than 60 volts.

32. The second battery module is connected in series to the first battery module, a low voltage side of the first transformer connected in series with a low voltage side of the second transformer; 22. The power conversion system of claim 21, wherein the first current source converter bridge is configured to operate in a switching cycle.

33. 33. The power conversion system of claim 32, wherein the switching cycle comprises a cross-clamp phase in which power is at least transferred from at least one of the first transformer and the second transformer through at least one clamping device to opposite poles of at least one of the first battery module and the second battery module.

34. 22. The power conversion system of claim 21, wherein the first galvanic converter bridge is configured such that a majority of leakage energy from at least one of the first transformer and the second transformer is recovered to at least one of the first battery module and the second battery module.

35. 22. The power conversion system of claim 21, wherein the power conversion system is configured to operate in a fail-safe state, wherein all controllable power devices connected to the first current source converter bridge, the second current source converter bridge, and the third current source converter bridge are turned off, and a magnetizing current of at least one of the first transformer and the second transformer is discharged into at least one of the first battery module and the second battery module.

36. 22. The power conversion system of claim 21, wherein one of the ports of the second current source converter bridge and the third current source converter bridge is a first port connected to a first electric motor.

37. 22. The power conversion system of claim 21 , wherein two of the ports of the second current source converter bridge and the third current source converter bridge are a first port connected to a first electric motor and a second port connected to a charging terminal.

38. 38. The power conversion system of claim 37, wherein another port of the second current source converter bridge and the third current source converter bridge is a third port connected to a second electric motor.

39. 37. The power conversion system of claim 36, wherein the other port of the current source converter is a second port connected to a second electric motor.

40. A first power conversion system according to any one of claims 1 to 39; A second power conversion system according to any one of claims 1 to 39, each of the power conversion systems includes the second battery module connected in series with the first battery module and a low-voltage side of the first transformer connected in series with a low-voltage side of the second transformer; A modular battery system, wherein the first power conversion system and the second power conversion system are connected in parallel to at least one of the ports of the first power conversion system and the second power conversion system configured to transmit power to and / or receive power from an electrical load and / or a power source.

41. A first battery module; a second battery module connected in series with the first battery module; a first transformer having a low voltage side and a high voltage side; a second transformer having a low voltage side and a high voltage side, the low voltage side of the first transformer being connected in series with the low voltage side of the second transformer; a first current source converter bridge configured to connect the first battery module and the second battery module with a low voltage side of the first transformer and the second transformer, wherein a midpoint of the series connection of the first battery module and the second battery module is connected to a midpoint of the series connection of the first transformer and the second transformer; a second current source converter bridge configured to connect to a high voltage side of the first transformer and to one or more ports configured to deliver power to and / or receive power from an electrical load and / or a power source; A power conversion system comprising: a third current source converter bridge configured to connect to a high voltage side of the second transformer and to one or more ports configured to transmit power to and / or receive power from an electrical load and / or a power source.

42. The second current source converter bridge comprises a first resonant circuit connected in parallel with a high voltage side of the first transformer; 42. The power conversion system of claim 41, wherein the third current source converter bridge comprises a second resonant circuit connected in parallel with a high voltage side of the second transformer.

43. The first current source converter bridge includes a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low voltage side terminal of the first transformer; the first switching circuit comprises a first controllable switch connected in series with a second switch; the first controllable switch is a Si MOSFET; or the second switch is one of a diode, a controllable switch, and a GaN HEMT; 42. The power conversion system of claim 41, wherein the power conversion system is at least one of:

44. The first current source converter bridge includes a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low voltage side terminal of the first transformer; The first switching circuit includes: a first controllable switch connected in series with a second switch; a first resonant pole network connected in parallel with the first and second controllable switches connected in series; and / or the first resonant pole network is configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the first switching circuit; or the first resonant pole network comprising a capacitor connected in series with a resistor-diode circuit that provides a different impedance during charging and discharging of the capacitor of the first resonant pole network; 42. The power conversion system of claim 41, wherein the power conversion system is at least one of:

45. The first current source converter bridge includes a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low voltage side terminal of the first transformer; 42. The power conversion system of claim 41, wherein the first switching circuit comprises a first clamping device configured to transfer power from the first transformer to the second battery module.

46. ​​The method of claim 46, wherein the first clamping device is one of a diode, a controllable switch, and a GaN HEMT; and / or The first switching circuit includes: a first controllable switch connected in series with a second switch; 46. ​​The power conversion system of claim 45, further comprising: a bypass capacitor connected in series with the first clamping device such that the series connection of the bypass capacitor and the first clamping device is connected in parallel with the first controllable switch which is connected in series with the second switch.

47. The first current source converter bridge includes a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage side terminal of the second transformer; the second switching circuit comprises a first controllable switch connected in series with a second switch; the first controllable switch is a Si MOSFET; the second switch is one of a diode, a controllable switch, and a GaN HEMT; 42. The power conversion system of claim 41, wherein the second switching circuit further comprises a second resonant pole network connected in parallel with the series connected first controllable switch and second switch.

48. The second resonant pole network is configured to enable ZVS turn-off and ZCS turn-on of the first controllable switch of the second switching circuit; or the second resonant pole network comprising a capacitor connected in series with a resistor-diode circuit that provides a different impedance during charging and discharging of the capacitor of the second resonant pole network.

48. The power conversion system of claim 47, wherein the power conversion system is at least one of:

49. The first current source converter bridge includes a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage side terminal of the second transformer; 42. The power conversion system of claim 41, wherein the second switching circuit comprises a second clamping device configured to transmit power from the second transformer to the first battery module.

50. The method according to claim 50, wherein the second clamping device is one of a diode, a controllable switch, and a GaN HEMT; and / or The second switching circuit includes: a first controllable switch connected in series with a second switch; 50. The power conversion system of claim 49 comprising: a bypass capacitor connected in series with the second clamping device such that the series connection of the bypass capacitor and the second clamping device is connected in parallel with the first controllable switch which is connected in series with the second switch.

51. The first current source converter bridge includes a first switching circuit configured to selectively connect a first pole of the first battery module and an opposite pole of the second battery module to a low voltage side terminal of the first transformer; the first switching circuit comprises a first controllable switch connected in series with a second switch; the first switching circuit further comprises a first clamping device configured to transmit power from the first transformer to the second battery module; the first current source converter bridge further comprises a second switching circuit configured to selectively connect a first pole of the second battery module and an opposite pole of the first battery module to a low voltage side terminal of the second transformer; the second switching circuit comprises a first controllable switch connected in series with a second switch; the second switching circuit further comprises a second clamping device configured to transmit power from the second transformer to the first battery module; the first controllable switch connected in series with the second switch of the first switching circuit is connected in series with the second clamping device of the second switching circuit; 42. The power conversion system of claim 41 , wherein the first clamping device of the first switching circuit is connected in series with the series connected first controllable switch and second switch of the second switching circuit.

52. At least one of the second current source converter bridge and the third current source converter bridge includes at least one reverse blocking switch; At least one of the reverse blocking switches is A controllable switch in series with a diode, or A first controllable switch and a second controllable switch connected in series with opposite current blocking directions 42. The power conversion system of claim 41, comprising:

53. The power conversion system is configured such that when the first current source converter bridge, the second current source converter bridge, and the third current source converter bridge are inactive, a maximum voltage of the system is a voltage level of the first battery module or the second battery module; or the voltage level of the first battery module or the second battery module is less than 60 volts; 42. The power conversion system of claim 41, wherein the power conversion system is at least one of:

54. The first current source converter bridge configured to operate in a switching cycle, 42. The power conversion system of claim 41, wherein the switching cycle comprises a cross-clamp phase, and power is transferred from at least one of the first transformer and the second transformer through at least one clamping device to at least opposite battery poles.

55. A first power conversion system according to any one of claims 41 to 54; A second power conversion system according to any one of claims 41 to 54, A modular battery system, wherein the first power conversion system and the second power conversion system are connected in parallel to at least one of one or more ports of the first power conversion system and the second power conversion system configured to transmit power to and / or receive power from an electrical load and / or a power source.

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