A modular high-voltage battery power DC control system

Abstract

This invention discloses a multi-modular high-voltage battery energy DC control system, comprising n electrically independent low-voltage battery sub-packs; each low-voltage battery sub-pack is composed of N cells connected in series; the positive and negative terminals of each low-voltage battery sub-pack are respectively connected to the input terminals of an independent modular isolated bidirectional DC / DC converter, and there is no electrical connection between the input terminals of each modular isolated bidirectional DC / DC converter; an output capacitor is connected in parallel to the output terminal of each modular isolated bidirectional DC / DC converter, the positive terminals of all output capacitors are connected to the positive terminal of the high-voltage DC bus, and the negative terminals of all output capacitors are connected to the negative terminal of the high-voltage DC bus; this system overcomes the limitations of traditional series battery packs, significantly improving the reliability, maintainability, and platform adaptability of the system while ensuring high energy density and fast charging performance.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a multi-modular high-voltage battery power DC control system. Background Technology

[0002] In the field of electric vehicle technology, the high-voltage battery pack, as the core component for energy storage and supply in the vehicle, has a decisive impact on the vehicle's performance, safety, and cost. Currently, mainstream high-voltage battery systems generally employ a large number of cells connected in series to construct a 400V or 800V voltage platform to meet the power supply requirements of the drive motor and other high-voltage loads. Among these, ternary lithium batteries and lithium iron phosphate batteries are widely used in different vehicle models due to their differences in energy density, thermal stability, and cycle life. To achieve a 400V system voltage, typically 100 to 156 cells need to be connected in series; while on an 800V platform, the number of cells connected in series further increases to 190 to 313. Although this high-number-of-cells architecture can achieve the required bus voltage, it has revealed many inherent defects in practical applications.

[0003] First, ensuring the consistency of battery cells after assembly is difficult. Minor individual differences are significantly amplified in long string structures, leading to a prominent bottleneck effect. Some cells are prone to overcharging or over-discharging, severely limiting the overall capacity, cycle life, and energy utilization efficiency of the battery pack. Second, as the number of battery cells increases, the monitoring and balancing of the battery management system (BMS) becomes dramatically more challenging. A large number of sampling points not only increases the complexity of signal acquisition and the risk of electromagnetic interference but also makes passive balancing time-consuming and inefficient, while active balancing faces challenges such as complex energy transfer paths, cumbersome control logic, and increased losses. Furthermore, traditional series architectures are difficult to manage thermally. Under high-power fast charging or high-rate discharging conditions, localized temperature rise is difficult to control uniformly, easily leading to thermal runaway risks and threatening vehicle safety.

[0004] More critically, the existing architecture lacks an effective fault tolerance mechanism. Once a single cell or module experiences a short circuit, open circuit, or thermal runaway, the entire battery string often needs to be disconnected, leading to a system power outage and virtually zero redundancy. Furthermore, since the high-voltage bus is directly formed by the series connection of cells, maintenance or replacement of faulty units requires system shutdown and involves high-voltage risks, significantly increasing after-sales costs and safety concerns. Although the industry is actively promoting 800V high-voltage platforms to improve charging efficiency and shorten recharge time, and exploring various architectural solutions to be compatible with 400V and 800V systems, the fundamental problems caused by the series structure mentioned above remain unresolved.

[0005] Against this backdrop, modular power supply technology and the modular multilevel converter (MMC) concept offer new insights for high-voltage power supply systems. Modular power supplies, with their advantages of high efficiency, high reliability, flexible expansion, and support for redundant design, have been maturely applied in aerospace, communications, and other fields. MMCs, through the coordinated output of stepped-wave voltages from multiple sub-modules, exhibit excellent voltage equalization capabilities and system stability in high-voltage, high-power scenarios. However, effectively integrating and adapting these technologies to high-voltage battery systems for electric vehicles, especially in achieving 400V / 800V platform compatibility, improving system redundancy, simplifying the BMS burden, and enhancing safety, still lacks practical technical solutions. Therefore, a new high-voltage power supply architecture is urgently needed that can overcome the limitations of traditional series-connected battery packs, significantly improving system reliability, maintainability, and platform adaptability while ensuring high energy density and fast-charging performance. Summary of the Invention

[0006] This invention addresses the shortcomings of existing electric vehicle high-voltage battery systems, which commonly use direct series connection of cells to form 400V or 800V high-voltage battery packs. These shortcomings include poor platform compatibility, low system reliability, easy fault propagation, difficult maintenance, and high safety risks. To address these issues, this invention proposes a multi-modal high-voltage battery energy DC control system. By reconstructing the internal electrical connections and energy management mechanisms of the battery pack, this system achieves flexible voltage platform adaptation, active fault isolation control, bidirectional energy flow regulation, and module-level online maintenance capabilities without relying on traditional passive protection devices such as high-voltage relays and fuses.

[0007] This application provides a multi-modular high-voltage battery energy DC control system, including n electrically independent low-voltage energy storage sub-packets; each low-voltage energy storage sub-packet is composed of N energy storage units connected in series; the positive and negative terminals of each low-voltage energy storage sub-packet are respectively connected to the input terminal of an independent modular isolated bidirectional DC / DC converter, and there is no electrical connection between the input terminals of each modular isolated bidirectional DC / DC converter; an output capacitor is connected in parallel to the output terminal of each modular isolated bidirectional DC / DC converter, the positive terminals of all output capacitors are connected to the positive terminal of the high-voltage DC bus, and the negative terminals of all output capacitors are connected to the negative terminal of the high-voltage DC bus.

[0008] Preferably, the low-voltage energy storage subpack is a low-voltage battery subpack, and the energy storage unit is a battery cell.

[0009] Preferably, the modular isolated bidirectional DC / DC converter adopts a dual active bridge topology or a CLLLC resonant topology, and its power switching devices are gallium nitride or silicon carbide wide bandgap semiconductor devices.

[0010] Preferably, the dual active bridge topology includes a primary-side full bridge and a secondary-side full bridge. The primary-side full bridge consists of four power switching transistors connected to the primary winding of the high-frequency isolation transformer via a resonant inductor. The secondary-side full bridge consists of four power switching transistors connected to the secondary winding of the high-frequency isolation transformer.

[0011] Preferably, the CLLLC resonant topology adds a resonant capacitor to the dual active bridge topology. This resonant capacitor, together with the resonant inductor and the leakage inductance of the high-frequency isolation transformer, forms a third-order resonant network.

[0012] Preferably, each modular isolated bidirectional DC / DC converter has a built-in microcontroller that communicates with the vehicle battery management system or vehicle controller via a CAN bus or CAN FD bus to receive power distribution commands, report operating status information, identify module plugging and unplugging actions, and execute interlocking control.

[0013] Preferably, when any modular isolated bidirectional DC / DC converter receives a latch-up command or detects a local fault, its built-in microcontroller shuts down all power switches and reduces the voltage on the corresponding output capacitor to zero, thereby achieving electrical isolation between the module and the high-voltage DC bus.

[0014] Preferably, the system supports module-level hot-swappable operation. Before a new module is connected to the high-voltage DC bus, its built-in microcontroller detects the bus voltage and pre-charges the output capacitor. Before the module is unplugged, a soft shutdown process is executed to ensure that the output capacitor is discharged.

[0015] Preferably, when applied to a 400V platform, m low-voltage battery sub-packs are configured, and when applied to an 800V platform, 2m low-voltage battery sub-packs of the same specifications are configured, where m is a positive integer.

[0016] Preferably, it also includes at least one supercapacitor module and its dedicated isolated bidirectional DC / DC converter, the output of which is connected in parallel to the high-voltage DC bus.

[0017] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. A modular architecture with complete input-side decoupling is adopted, where multiple low-voltage battery sub-packs are connected in parallel to the high-voltage DC bus via independent isolated bidirectional DC / DC converters. This solves the problems of fault propagation risk, difficulty in cell consistency management, and high-voltage safety hazards caused by the direct series connection of a large number of cells in traditional high-voltage battery packs. It achieves independent and precise management of each battery sub-pack, electrical isolation of faults, and low-voltage safety during operation and maintenance.

[0018] 2. A GaN / SiC-based dual active bridge or CLLLC resonant isolated bidirectional DC / DC converter is adopted. This solves the problems of low efficiency and limited power density of traditional hard-switching converters. It achieves high-frequency soft-switching operation, high-efficiency bidirectional energy flow, and allows for flexible adjustment of voltage gain through phase shifting or frequency conversion control, providing a stable and reliable high-voltage output for the system.

[0019] 3. A distributed fault-tolerance mechanism based on output capacitor connection and software control is adopted. This solves the "single point of failure" problem, where a failure of any sub-package or converter module in the system could lead to the failure of the entire power supply system. It enables rapid electrical isolation of the faulty module, and allows the remaining normal modules to adaptively increase their output through control algorithms to maintain stable bus voltage and achieve redundant power supply capability.

[0020] 4. A collaborative control system supporting hot-swappable communication protocols and parallel expansion of heterogeneous energy sources is adopted. This solves the problems of the system's inability to be maintained and expanded online, and the battery's inability to cope with instantaneous high-power surges. It enables modules to be connected and disconnected without interrupting system operation, and through dynamic power allocation, utilizes supercapacitors to handle peak power, thereby extending battery life and improving the vehicle's power response and energy utilization efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the modular high-voltage power battery pack scheme with independent input and parallel output according to the present invention; Figure 2 This is a topology diagram of the modular bidirectional isolated DC / DC converter of the present invention; Figure 3 This is an example diagram of the modular power supply scheme using a DAB converter in this invention; Figure 4 This is an example diagram of the modular power supply fault tolerance mechanism using a DAB converter in this invention; Figure 5 This is a schematic diagram of the heterogeneous power supply structure with a supercapacitor and a battery pack according to the present invention. Detailed Implementation

[0022] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0023] Specific embodiments of the present invention are described in conjunction with the appendix. Figures 1 to 5 Please provide a detailed explanation. For example... Figure 1 As shown, the multi-modular high-voltage battery power DC control system proposed in this invention includes n electrically independent low-voltage battery sub-packs (Pack1…Pack2…Pack3…Pack4…Pack5…Pack6…Pack7…Pack8 ... nEach sub-pack consists of a limited number of cells connected in series, with a nominal voltage set at a safety extra-low voltage level such as 48V, 72V, or 96V; the positive and negative terminals of each low-voltage battery sub-pack are respectively connected to an independent modular isolated bidirectional DC / DC converter (Module1…Module). n The input terminals of each DC / DC converter are completely decoupled, with no electrical connection between them. Each DC / DC converter's output terminal is connected in parallel with an output capacitor (C1… ... n All output capacitors C1 to C n The positive terminals are connected together to the high-voltage DC bus V. o The positive terminal, all output capacitors C1 to C n The negative terminals are connected together to the high-voltage DC bus V. o The negative terminal is connected to form a parallel connection on the output side, constructing the 400V or 800V high-voltage DC power supply platform required by the entire vehicle. This architecture differs from the traditional method of directly connecting a large number of cells in series to form a high-voltage battery pack. By sinking the energy management unit to the level of each battery sub-pack, it achieves independent charging and discharging control and fault isolation for each sub-pack.

[0024] like Figure 2 As shown, the modular DC / DC isolated bidirectional converter adopts a dual active bridge (DAB) or CLLLC resonant topology. Taking the DAB topology as an example, its primary side consists of four gallium nitride (GaN) or silicon carbide (SiC) power switches Q1–Q4 forming a full-bridge structure, which is connected to the primary winding of the high-frequency isolation transformer T via a resonant inductor Lr; the secondary side also consists of four GaN / SiC power switches Q5–Q8 forming a full-bridge structure, which is connected to the secondary winding of the high-frequency isolation transformer T, and the energy is transferred to the output capacitor Co (i.e., ...) through synchronous rectification. Figure 3 C1…C n In the CLLLC topology, a resonant capacitor Cr is added to the primary or secondary side of the DAB topology. This, along with the resonant inductor Lr and the transformer leakage inductance, forms a third-order resonant network to extend the zero-voltage switching (ZVS) operating range and further reduce switching losses. Both topologies support bidirectional energy flow: under discharge conditions, the low-voltage battery subpack boosts the energy through a DC / DC converter and injects it into the high-voltage bus V. o Under charging conditions, the high-voltage bus V o The energy is stepped down by a DC / DC converter to independently charge the corresponding battery sub-packs. The converter adjusts the voltage gain through phase-shift control or frequency modulation to ensure stable bus voltage under different load and battery state conditions.

[0025] like Figure 3As shown, in a typical embodiment using the DAB topology, battery pack Pack1 is connected to the DAB converter DC / DC1, and its output is connected in parallel with capacitor C1; similarly, battery pack Pack2 is connected to Pack... n Connect the DAB converter DC / DC2 to DC / DC in sequence. n And capacitors C2 to C are connected in parallel respectively. n For example, when n=10 and the nominal voltage of each pack is 96V, after the 10 sub-packs are boosted by their respective DC / DC converters, their output capacitors C1 to C... 10 They are connected in parallel to form a 960V high-voltage DC bus V o It is compatible with 800V platform applications; if applied to a 400V platform, five sub-packages of the same specifications can be configured, making 5 × 96V ≈ 480V, and then the bus voltage can be stabilized within the range of 400V ± 5% through control strategies. All DC / DC converters are based on GaN / SiC wide bandgap devices to achieve high-frequency soft-switching operation, with switching frequencies reaching hundreds of kHz, significantly improving power density and conversion efficiency.

[0026] like Figure 4 As shown, this invention possesses a robust fault-tolerance mechanism. When any sub-packet (e.g., Pack2) experiences an internal short circuit, open circuit, over-temperature, or thermal runaway fault, or when its corresponding DC / DC converter (e.g., DC / DC2) experiences power device breakdown, drive failure, or communication interruption, the microcontroller (MCU) built into the module immediately triggers the latching logic, stops the PWM signal output, and shuts down all power switches Q1–Q8, causing the converter to cease energy conversion. Since the converter output is only connected to the high-voltage bus Vo through the output capacitor C2, and there is no diode or mechanical switch to maintain the circuit, the voltage on C2 rapidly decays to zero under the load current after latching, achieving electrical isolation between the faulty module and the high-voltage bus. Simultaneously, the vehicle battery management system (BMS) or vehicle controller (VCU) communicates via CAN / CAN After receiving a fault report, the FD bus recalculates the power ratio required by each module based on the number of remaining normal modules (e.g., n−1=9) and sends gain boost commands to the remaining 9 DC / DC converters. Each normal module increases its voltage gain by increasing the phase shift angle (in DAB topology) or decreasing the switching frequency (in CLLLC topology) to maintain its output voltage at the target bus voltage level (e.g., 800V±5%), thereby compensating for the voltage drop caused by the faulty module's exit and ensuring the high-voltage DC bus V o A continuous and stable power supply is achieved, realizing (N-1) level redundancy. If multiple modules fail simultaneously, the system can still adaptively adjust the control parameters according to the number of remaining modules to maintain a minimum power supply capacity, achieving (N-x) level redundancy and fault tolerance.

[0027] Each modular DC / DC converter has a built-in MCU that establishes real-time data interaction with the vehicle's BMS / VCU via CAN or CAN FD communication bus.

[0028] The MCU performs the following functions: S1 receives power allocation commands from BMS / VCU and dynamically adjusts the phase shift angle or switching frequency of this module to regulate the output power. S2 monitors the input voltage, output voltage, current, temperature and fault status of this module, and periodically reports the above information to BMS / VCU; S3, identify whether this module has been inserted into or removed from the system, and execute hot-plug initialization or safe exit process; S4, upon receiving a lockout command or detecting a local fault, immediately shuts off all power switches and disconnects the electrical connection to the high-voltage bus.

[0029] The system supports module-level hot-swapping: newly added battery sub-packs and corresponding DC / DC converter modules can be connected to the high-voltage bus while the vehicle is in operation. The MCU of the new module first detects the bus voltage V. o After the output capacitor is pre-charged to the bus voltage level, the converter is started and connected to the system. Similarly, faulty or aging modules can be removed without power interruption. Before removal, the MCU performs a soft shutdown process to ensure that the output capacitor is discharged before disconnecting the physical connection, thereby realizing online expansion of battery system capacity and rapid replacement of faulty units.

[0030] like Figure 5 As shown, the architecture of this invention can be further extended into a heterogeneous energy collaborative power supply system. Based on the aforementioned n battery sub-packs and corresponding DC / DC converters, at least one supercapacitor bank and its dedicated isolated bidirectional DC / DC interface converter are added; the rated voltage of this supercapacitor bank is also at the safe extra-low voltage level (e.g., 48V), and its DC / DC converter output is connected in parallel to the same high-voltage DC bus V. o Under conditions of rapid vehicle acceleration or strong regenerative braking, the supercapacitor module rapidly absorbs or releases instantaneous high power through its DC / DC converter to meet peak power demands. Under steady-state driving or normal charging and discharging conditions, energy is mainly provided or stored by the battery sub-pack. The BMS / VCU dynamically allocates the power contribution ratio between the battery and the supercapacitor based on the vehicle's power requirements, battery SOC, and supercapacitor state of charge, thereby reducing the battery's charge and discharge rate, delaying battery aging, and improving the vehicle's power response performance and energy utilization efficiency.

[0031] In actual operation, when the electric vehicle is in normal driving condition, the BMS issues power distribution commands to each DC / DC converter according to the vehicle's power demand command, and each module outputs power to the high-voltage bus V proportionally. o This includes high-voltage loads such as the drive motor controller, PTC heater, and air conditioning compressor; when the vehicle is fast-charging, the 800V or 400V DC power provided by the external charging pile is connected to the on-board charger or directly to the high-voltage bus V. o Each DC / DC converter operates in reverse, stepping down the bus voltage to independently charge its respective connected battery sub-packs using constant current and constant voltage, achieving precise charging management at the sub-pack level and avoiding overcharging or undercharging issues caused by cell inconsistency in traditional series battery packs. In low-temperature environments, the BMS can instruct some DC / DC converters to pulse-heat specific sub-packs to improve battery activity without relying on external heating devices. In collision or severe fault scenarios, the BMS can remotely lock all or some DC / DC converters to quickly cut off the high-voltage bus energy source, improving vehicle safety.

[0032] Since the nominal voltage of each low-voltage battery sub-pack does not exceed 100V, the risk of electric shock and arcing faced by operators when handling individual sub-packs during manufacturing, assembly, maintenance, and recycling is significantly reduced. Simultaneously, any thermal runaway or electrical fault within a sub-pack is confined to the input side of its corresponding DC / DC converter, preventing it from being conducted to other sub-packs or the high-voltage bus via a series path. This avoids the chain reaction and vehicle-wide safety accidents caused by single-cell failures found in traditional series battery packs. Furthermore, because all peripheral high-voltage components (such as high-voltage connectors, wiring harnesses, contactors, and fuses) are connected to the same high-voltage bus V... o Its rated voltage only needs to cover 800V to be compatible with both 400V and 800V platforms. The control strategy can be switched via software configuration without changing the hardware circuit, significantly reducing the platform derivative development cost and supply chain complexity. In summary, this invention achieves a balance of high compatibility, high reliability, high safety, and high maintainability through modular, intelligent, and redundant design, providing a complete technical solution for next-generation electric vehicle high-voltage energy systems.

[0033] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made to the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention. Although preferred embodiments of the present invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A multi-modular high-voltage battery power DC control system, characterized in that, It includes n electrically independent low-voltage energy storage sub-packets; each low-voltage energy storage sub-packet is composed of N energy storage units connected in series; the positive and negative terminals of each low-voltage energy storage sub-packet are respectively connected to the input terminal of an independent modular isolated bidirectional DC / DC converter, and there is no electrical connection between the input terminals of each modular isolated bidirectional DC / DC converter; an output capacitor is connected in parallel to the output terminal of each modular isolated bidirectional DC / DC converter, the positive terminals of all output capacitors are connected to the positive terminal of the high-voltage DC bus, and the negative terminals of all output capacitors are connected to the negative terminal of the high-voltage DC bus.

2. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, The low-voltage energy storage subpack uses a low-voltage battery subpack, and the energy storage unit uses a battery cell.

3. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, The modular isolated bidirectional DC / DC converter adopts a dual active bridge topology or a CLLLC resonant topology, and its power switching devices are gallium nitride or silicon carbide wide bandgap semiconductor devices.

4. The multi-modular high-voltage battery power DC control system as described in claim 3, characterized in that, The dual active bridge topology includes a primary-side full bridge and a secondary-side full bridge. The primary-side full bridge consists of four power switching transistors connected to the primary winding of the high-frequency isolation transformer via a resonant inductor. The secondary-side full bridge consists of four power switching transistors connected to the secondary winding of the high-frequency isolation transformer.

5. The multi-modular high-voltage battery power DC control system as described in claim 3, characterized in that, The CLLLC resonant topology adds a resonant capacitor to the dual active bridge topology. This resonant capacitor, together with the resonant inductor and the leakage inductance of the high-frequency isolation transformer, forms a third-order resonant network.

6. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, The modular isolated bidirectional DC / DC converter has a built-in microcontroller that communicates with the vehicle battery management system or vehicle controller via a CAN bus or CAN FD bus. The microcontroller is used to receive power distribution commands, report operating status information, identify module plugging and unplugging actions, and execute interlocking control.

7. The multi-modular high-voltage battery power DC control system as described in claim 3, characterized in that, When the modular isolated bidirectional DC / DC converter receives a lockout command or detects a local fault, its built-in microcontroller shuts down all power switches and reduces the voltage on the corresponding output capacitor to zero, thereby achieving electrical isolation between the module and the high-voltage DC bus.

8. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, The system supports module-level hot-swappable operation. Before a new module is connected to the high-voltage DC bus, its built-in microcontroller detects the bus voltage and pre-charges the output capacitor. Before the module is unplugged, a soft shutdown process is executed to ensure that the output capacitor is discharged.

9. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, When the system is applied to a 400V platform, it is configured with m low-voltage battery sub-packs; when applied to an 800V platform, it is configured with 2m low-voltage battery sub-packs of the same specifications, where m is a positive integer.

10. The multi-modular high-voltage battery power DC control system as described in claim 1, characterized in that, The system also includes at least one supercapacitor module and its dedicated isolated bidirectional DC / DC converter, the output of which is connected in parallel to the high-voltage DC bus.

Images