An electric commercial vehicle high-voltage fast charging system and a charging control method

Abstract

This invention relates to a high-voltage fast charging system and charging control method for electric commercial vehicles. The system includes: a charging interface for connecting to a charging pile to receive charging voltage; a high-voltage electrical component group; a battery pack assembly including two first battery pack units and two second battery pack units, wherein the voltage level of the first battery pack units is higher than that of the second battery pack units; a first switch group and a second switch group for switching the series-parallel connection mode between the first and second battery pack units, so that the battery pack assembly forms a first operating voltage in a first connection state and a second operating voltage higher than the first operating voltage in a second connection state; a third switch group for connecting the battery pack assembly to the charging interface; a pre-charging circuit for connecting the battery pack assembly to the high-voltage electrical component group; and a controller electrically connected to the first, third, and second switch groups for controlling the on / off state of each switch group according to the operating mode. Specifically, in discharge mode and normal charging mode, the first and second switch groups control the battery pack assembly in the first connection state; in high-voltage charging mode, the first and second switch groups control the battery pack assembly in the second connection state.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle charging technology, and in particular to a high-voltage fast charging system and charging control method for electric commercial vehicles. Background Technology

[0002] To meet the demands of long driving range and efficient operation of pure electric commercial vehicles, the capacity of power battery systems has reached a high level. However, traditional charging methods have the problem of excessively long charging times when dealing with large-capacity batteries, which seriously affects the operating efficiency of electric commercial vehicles. In order to shorten charging time and improve energy replenishment efficiency, increasing charging power has become an inevitable choice.

[0003] Currently, increasing charging power can be achieved by increasing the charging current or raising the charging voltage. However, considering that excessive charging current can lead to problems such as cable overheating, increased energy loss, and excessively high physical requirements for charging interfaces and cables, increasing the charging voltage to improve charging power has become a more feasible technical approach. Currently, super-fast charging stations supporting 1500V high-voltage platforms have appeared on the market. Compared to existing 800V charging platforms, under the same current conditions, the charging power can be increased by nearly 2 times, significantly shortening charging time.

[0004] However, when the charging voltage is increased to 1500V, the existing electrical systems of electric commercial vehicles face two prominent technical challenges: First, most existing power battery packs are designed based on an 800V-900V voltage platform. The insulation structure, number of cells connected in series, and withstand voltage level of high-voltage components inside the battery pack are all configured according to the 800V-900V standard. They cannot directly withstand a high voltage of 1500V, which poses insulation failure and safety risks. Secondly, high-voltage electrical components in vehicles, such as air conditioning compressors, PTC heaters, and DC-DC converters, are all products adapted to an 800V voltage platform. Their internal circuits and components are designed based on 800V for withstand voltage levels and operating voltage ranges. During 1500V charging, these electrical components will face a supply voltage far exceeding their rated operating voltage, making them unable to work properly and potentially causing damage due to overvoltage.

[0005] In existing technologies, adapting electric commercial vehicles to a 1500V super-fast charging system typically requires redesigning the entire high-voltage electrical system. This approach is not only costly to develop, but also presents significant challenges in terms of the reliability, cost, and supply chain maturity of 1500V-level high-voltage components. Furthermore, a completely redesigned approach cannot achieve technical compatibility and upgrades for existing 800V platform vehicles, resulting in a waste of resources.

[0006] Therefore, how to fully utilize existing 800V battery packs and high-voltage electrical components to support 1500V super-fast charging, enabling the battery pack to safely accept high-voltage charging while ensuring that the on-board high-voltage electrical components can still operate normally within their rated voltage range during charging, has become an urgent technical problem to be solved. Summary of the Invention

[0007] This invention discloses a high-voltage fast charging system and charging control method for electric commercial vehicles, aiming to solve the technical problems existing in the prior art. The invention adopts the following technical solution: On one hand, embodiments of the present invention provide a high-voltage fast charging system for electric commercial vehicles, comprising: - Charging interface, used to connect to a charging station to receive charging voltage; -High-voltage electrical components group; - A battery pack assembly, comprising two first battery pack units and two second battery pack units, wherein the voltage level of the first battery pack units is higher than that of the second battery pack units; - The first switch group and the second switch group are used to switch the series and parallel connection mode between the first battery pack unit and the second battery pack unit, so that the battery pack assembly forms a first working voltage in the first connection state and forms a second working voltage higher than the first working voltage in the second connection state. - The third switch group is used to connect the battery pack assembly to the charging interface; - Pre-charging circuit, used to connect the battery pack assembly to the high-voltage electrical components group; - The controller is electrically connected to the first switch group, the third switch group, and the second switch group, and is used to control the on / off state of each switch group according to the working mode. In the discharge mode and normal charging mode, the first switch group and the second switch group control the battery pack assembly to be in the first connection state; in the high-voltage charging mode, the first switch group and the second switch group control the battery pack assembly to be in the second connection state.

[0008] As a preferred technical solution, the first battery pack unit includes a battery pack with a rated voltage of 800V, and the second battery pack unit includes a battery pack with a rated voltage of 400V. In the first connection state, the two first battery pack units are connected in parallel, and the two second battery pack units are connected in series and then connected in parallel with the first battery pack units in the parallel state. The first working voltage is 800V. In the second connection state, a first battery pack unit and a second battery pack unit are connected in series to form a first series branch, and another first battery pack unit and another second battery pack unit are connected in series to form a second series branch. The first series branch and the second series branch are connected in parallel, and the second operating voltage is 1200V.

[0009] As a preferred technical solution, the first switch group includes a first relay, a second relay, and a third relay; The first relay is connected between a first battery pack unit and a second battery pack unit to control the series connection of the first series branch; The second relay is connected between the two second battery pack units and is used to control the series connection of the two second battery pack units; The third relay is connected between another first battery pack unit and another second battery pack unit to control the series connection of the second series branch.

[0010] As a preferred technical solution, the third switch group includes a sixth relay and a seventh relay; The sixth relay is located between the positive output terminal of the battery pack assembly and the positive terminal of the charging interface; The seventh relay is located between the negative output terminal of the battery pack assembly and the negative terminal of the charging interface.

[0011] As a preferred technical solution, the second switch group includes a fourth relay and a fifth relay; The fourth relay is installed on the first parallel branch leading from a first battery pack unit. The first parallel branch is connected to the first end of the pre-charging circuit and the positive end of the charging interface, respectively. The fifth relay is set on the second parallel branch leading from another first battery pack unit. The second parallel branch is connected to the second end of the pre-charging circuit and the negative end of the charging interface, respectively. The fourth and fifth relays are used to close in the first connection state to allow the battery pack assembly to supply power to the high-voltage electrical device group through the pre-charging circuit, and to form a charging circuit in conjunction with the third switch group in the normal charging mode.

[0012] As a preferred technical solution, the pre-charging circuit includes an eighth relay and a ninth relay; The eighth relay is connected in series with the pre-charge resistor and then in parallel across the ninth relay to form the pre-charge branch; The high-voltage electrical component group includes multiple high-voltage electrical components connected in parallel at the output terminal of the pre-charging circuit; The eighth relay is used to close during the pre-charging stage to pre-charge the high-voltage electrical device group through the pre-charging resistor; after the pre-charging is completed, the eighth relay opens and the ninth relay closes to supply power to the high-voltage electrical device group normally.

[0013] As a preferred technical solution, the controller is electrically connected to each relay in the first switch group, the second switch group, the third switch group and the pre-charging circuit, respectively, and is used to control the on / off state of each relay according to the current working mode. In discharge mode, the controller controls the second, fourth and fifth relays to close, controls the first, third, sixth and seventh relays to open, and controls the eighth and ninth relays to open according to the power demand of the high-voltage electrical components group. In normal charging mode, the controller controls the second, sixth, seventh, fourth and fifth relays to close, controls the first and third relays to open, and controls the eighth and ninth relays to open and close according to the power demand of the high-voltage electrical components group. In high-voltage charging mode, the controller controls the first, third, sixth, and seventh relays to close, controls the second, fourth, and fifth relays to open, and controls the eighth and ninth relays to open and close according to the power demand of the high-voltage electrical device group.

[0014] As a preferred technical solution, the controller is also used for: The system detects the charging enable signal sent from the charging pile to the BMS. When the charging enable signal is detected, it determines that the charging state has been entered. When the charging enable signal is not detected, it determines that the discharging mode has been entered. After entering the charging state, it receives message information sent by the charging pile, which includes the highest charging voltage parameter supported by the charging pile. The charging mode is determined based on the highest charging voltage parameter. When the highest charging voltage parameter is greater than or equal to a preset threshold, it is determined to enter the high-voltage charging mode; when the highest charging voltage parameter is less than the preset threshold, it is determined to enter the normal charging mode. The preset threshold is 1000V.

[0015] Secondly, embodiments of the present invention provide a charging control method, applied to the high-voltage fast charging system for electric commercial vehicles as described above, comprising the following steps: Detect the charging enable signal sent from the charging pile to the BMS; When a charging enable signal is detected, the system receives message information sent by the charging pile and determines the charging mode based on the highest charging voltage parameter in the message information. When the maximum charging voltage parameter is greater than or equal to the preset threshold, the second relay in the first switch group is opened, and the first and third relays are closed, so that the two first battery pack units are connected in series with the two second battery pack units respectively, the second switch group is opened and the third switch group is closed to perform high-voltage charging mode charging; When the maximum charging voltage parameter is less than the preset threshold, the first and third relays in the first switch group are opened and the second relay is closed. The second switch group is closed, so that the two second battery pack units are connected in series and then connected in parallel with the two first battery pack units. The third switch group is closed to perform charging in normal charging mode. When no charging enable signal is detected, the first and third relays in the first switch group are opened and the second relay is closed, closing the second switch group, so that the two second battery pack units are connected in series and then connected in parallel with the two first battery pack units to perform high-voltage power-on in discharge mode.

[0016] As a preferred technical solution, the charging control method further includes: Real-time detection of power demand signals of high-voltage electrical components in high-voltage charging mode, normal charging mode or discharging mode; When a power demand is detected in the high-voltage electrical component group, the pre-charging control process is executed: First, control the eighth relay to close and the ninth relay to remain open. Then, precharge the high-voltage electrical device group through the pre-charging resistor until the terminal voltage of the high-voltage electrical device group reaches the preset voltage threshold. Then, control the ninth relay to close and the eighth relay to open, establishing a direct electrical connection between the battery pack assembly and the high-voltage electrical components group; When the power demand of the high-voltage electrical components group ends, the ninth relay is disconnected.

[0017] One embodiment of the above invention has the following advantages or beneficial effects: This invention provides a high-voltage fast charging system and charging control method for electric commercial vehicles. Through battery pack reconfiguration and intelligent power distribution switching, it effectively solves two core problems faced by electric commercial vehicles in ultra-high voltage charging scenarios. The system, through the coordinated control of the first and second switch groups, can flexibly switch the series and parallel connection modes of battery pack components, enabling the battery pack, originally designed for an 800V voltage platform, to be compatible with 1500V ultra-high voltage charging piles. While keeping the battery pack itself unchanged, the charging voltage is increased from 800V to 1200V, thereby achieving a nearly 2-fold increase in charging power under the same current conditions, significantly shortening the charging time and meeting the actual needs of commercial vehicles for rapid energy replenishment.

[0018] Furthermore, the system, through the cooperation of the pre-charging circuit and the second switch group, solves the technical bottleneck of the inability of on-board high-voltage electrical components to operate in high-voltage charging scenarios. In 1200V high-voltage charging mode, high-voltage electrical components such as air conditioners and PTC heaters, which are originally designed for 800V voltage platforms, can still operate stably within their rated 800V voltage range through intelligent switching of the power distribution circuit, avoiding the risk of equipment damage due to excessive voltage. This feature allows the vehicle to operate normally with comfort equipment such as air conditioning and heating in the cab while it is undergoing ultra-high-voltage fast charging, ensuring a comfortable experience for the driver while waiting for charging.

[0019] Furthermore, the system's controller can automatically identify the voltage capability of the charging pile and intelligently select either high-voltage charging mode or normal charging mode based on the highest charging voltage supported by the charging pile. This achieves broad compatibility with different charging piles. The entire system does not require upgrading the voltage level of existing high-voltage electrical components. By simply optimizing the electrical topology and coordinating the control of relay groups, a smooth switch from normal charging to ultra-high-voltage fast charging can be achieved, significantly reducing the technical implementation cost and providing a practical technical solution for the large-scale promotion and application of electric commercial vehicles. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a schematic diagram of the circuit structure of a high-voltage fast charging system for electric commercial vehicles disclosed in one embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit structure of a high-voltage fast charging system for electric commercial vehicles disclosed in a specific embodiment of the present invention; Figure 3 This is a flowchart of a charging control method disclosed in one embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: First battery pack unit 101, second battery pack unit 102, first relay 103, second relay 104, third relay 105, fourth relay 106, fifth relay 107, sixth relay 108, seventh relay 109, eighth relay 110, ninth relay 111, air conditioner 112, PTC heater 113. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0024] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] refer to Figure 1 To address the problems existing in the prior art, this invention provides a high-voltage fast charging system for electric commercial vehicles. The system includes a charging interface, a high-voltage electrical component group, a battery pack assembly, a first switch group, a second switch group, a third switch group, a pre-charging circuit, and a controller. The charging interface is used to connect to a charging pile to receive charging voltage. The battery pack assembly includes two first battery pack units 101 and two second battery pack units 102. The voltage level of the first battery pack units 101 is higher than that of the second battery pack units 102. The first and second switch groups are used to switch the series-parallel connection between the first battery pack units 101 and the second battery pack units 102. The method involves the battery pack assembly to generate a first operating voltage in a first connected state and a second operating voltage higher than the first operating voltage in a second connected state. A third switch group is used to connect the battery pack assembly to the charging interface, and a pre-charging circuit is used to connect the battery pack assembly to the high-voltage electrical components group. The controller is electrically connected to the first switch group, the third switch group, and the second switch group, and is used to control the on / off state of each switch group according to the operating mode. Specifically, in the discharge mode and the normal charging mode, the first switch group and the second switch group control the battery pack assembly to be in the first connected state; in the high-voltage charging mode, the first switch group and the second switch group control the battery pack assembly to be in the second connected state.

[0026] In a preferred embodiment, the first battery pack unit 101 includes a battery pack with a rated voltage of 800V, and the second battery pack unit 102 includes a battery pack with a rated voltage of 400V.

[0027] Preferably, in the first connection state, two first battery pack units 101 are connected in parallel, and two second battery pack units 102 are connected in series and then connected in parallel with the first battery pack units 101 in the parallel state, with a first operating voltage of 800V; in the second connection state, one first battery pack unit 101 and one second battery pack unit 102 are connected in series to form a first series branch, and another first battery pack unit 101 and another second battery pack unit 102 are connected in series to form a second series branch, with the first series branch and the second series branch connected in parallel, with a second operating voltage of 1200V.

[0028] Specifically, most mainstream electric commercial vehicles currently use an 800V high-voltage electrical platform. Onboard high-voltage electrical components such as the air conditioner 112 and PTC heater 113 are configured and selected according to the 800V voltage level. For this reason, the rated voltage of the first battery pack unit 101 is set to 800V, which can ensure that the entire electrical system operates within its rated voltage range in both discharge mode and normal charging mode, thus guaranteeing the normal operation and service life of each high-voltage electrical component.

[0029] The rated voltage of the second battery pack unit 102 is set to 400V to enable flexible voltage adjustment of the battery pack assembly under different connection states. Specifically, by connecting a 400V second battery pack unit 102 in series with an 800V first battery pack unit 101, a 1200V high-voltage branch can be formed, allowing the entire battery pack assembly to reach a working voltage of 1200V in the second connection state. This is to meet the charging requirements of the new generation of 1500V ultra-high voltage charging piles and significantly improve charging power while ensuring charging safety. At the same time, 400V is half of 800V, so that the two second battery pack units 102 connected in series can form a voltage match with the first battery pack unit 101, achieving a stable 800V working voltage output in the first connection state.

[0030] By configuring the battery pack components as described above, the system can achieve a voltage jump from 800V to 1200V simply by reconfiguring the topology without increasing the voltage level of individual battery packs. This avoids major modifications to existing battery pack technology and reduces the difficulty and cost of implementation.

[0031] In a preferred embodiment, the third switch group includes a sixth relay 108 and a seventh relay 109, wherein the sixth relay 108 is disposed between the positive output terminal of the battery pack assembly and the positive terminal of the charging interface, and the seventh relay 109 is disposed between the negative output terminal of the battery pack assembly and the negative terminal of the charging interface.

[0032] Specifically, during the charging process, whether in normal charging mode or high-voltage charging mode, the controller needs to simultaneously close the sixth relay 108 and the seventh relay 109 to establish a complete electrical path between the charging interface and the battery pack assembly. When the sixth relay 108 is closed, the positive terminal of the charging interface is connected to the positive output terminal of the battery pack assembly, and when the seventh relay 109 is closed, the negative terminal of the charging interface is connected to the negative output terminal of the battery pack assembly. At this time, the charging current output by the charging pile can flow into the battery pack assembly through the third switch group to charge the battery pack. In the non-charging state, both the sixth relay 108 and the seventh relay 109 are in the open state, physically isolating the battery pack assembly from the charging interface to prevent high voltage at the charging interface during vehicle operation or parking, ensuring safe use. Through the on / off control of the third switch group, electrical isolation between the charging mode and the discharging mode can be effectively achieved, preventing the formation of an unexpected current loop between the charging interface and the high-voltage electrical components.

[0033] In a preferred embodiment, the first switch group includes a first relay 103, a second relay 104, and a third relay 105; the first relay 103 is connected between a first battery pack unit 101 and a second battery pack unit 102, and its closure can control a first series branch to achieve a series connection; the second relay 104 is connected between two second battery pack units 102, and its closure can control two second battery pack units 102 to achieve a series connection; the third relay 105 is connected between another first battery pack unit 101 and another second battery pack unit 102, and its closure can control a second series branch to achieve a series connection.

[0034] Specifically, when the system needs to enter the second connection state to achieve 1200V high-voltage charging, the controller controls the first relay 103 and the third relay 105 to close. At this time, the positive terminal of one first battery pack unit 101 and the negative terminal of one second battery pack unit 102 are connected through the first relay 103 to form a first series branch, and the positive terminal of another first battery pack unit 101 and the negative terminal of another second battery pack unit 102 are connected through the third relay 105 to form a second series branch. Each of the two series branches outputs a 1200V voltage. In the first connection state, the first relay 103 and the third relay 105 are disconnected, and the second relay 104 is closed, so that the two second battery pack units 102 are connected in series. The 800V voltage after series connection can be matched with the 800V voltage of the two first battery pack units 101 in parallel.

[0035] In a preferred embodiment, the second switch group includes a fourth relay 106 and a fifth relay 107. The fourth relay 106 is disposed on a first parallel branch leading from one first battery pack unit 101. The first parallel branch is connected to both the first end of the pre-charging circuit to supply power to the high-voltage electrical device group and the positive terminal of the charging interface for charging. The fifth relay 107 is disposed on a second parallel branch leading from another first battery pack unit 101. The second parallel branch is connected to both the second end of the pre-charging circuit to form a complete power supply circuit and the negative terminal of the charging interface to form a complete charging circuit. When the fourth relay 106 and the fifth relay 107 are closed in the first connected state, the two first battery pack units 101 are connected in parallel through these two parallel branches. At the same time, due to the closure of the second relay 104, the two second battery pack units 102 connected in series are also connected in parallel with the first battery pack unit 101, ultimately forming a first operating voltage output of 800V.

[0036] In a preferred embodiment, the pre-charging circuit includes an eighth relay 110 and a ninth relay 111. The eighth relay 110 is connected in series with a pre-charging resistor and then connected in parallel across the ninth relay 111 to form a pre-charging branch. The high-voltage electrical device group includes multiple high-voltage electrical devices connected in parallel to the output terminal of the pre-charging circuit. The eighth relay 110 is used to close during the pre-charging stage to pre-charge the high-voltage electrical device group through the pre-charging resistor. After pre-charging is completed, the ninth relay 111 closes and the eighth relay 110 opens to supply power to the high-voltage electrical device group normally.

[0037] In a preferred embodiment, the high-voltage electrical component group includes an air conditioner 112 and a PTC heater 113, both of which are major power-consuming devices during vehicle operation. Their rated operating voltage matches the first operating voltage, i.e., both are configured with a voltage level of 800V. In discharge mode, the air conditioner 112 and the PTC heater 113 are connected to the battery pack assembly through a pre-charging circuit, and can directly obtain an 800V operating voltage from the battery pack assembly in the first connection state.

[0038] Besides the air conditioner 112 and the PTC heater 113, the high-voltage electrical component group can also include various on-board high-voltage electrical devices. The specific composition can be adjusted and expanded according to the functional configuration of different vehicle models and actual application scenarios. In this embodiment, only the air conditioner 112 and the PTC heater 113 are used as representative examples for illustration, and it is not limited to these. In practical applications, any high-voltage electrical device with a rated operating voltage of 800V can be connected to the battery pack assembly in parallel through the pre-charging circuit. This embodiment will not list or describe them in detail.

[0039] Specifically, during the pre-charge phase of the discharge mode, the controller first controls the eighth relay 110 to close, while the ninth relay 111 remains open. At this time, the output current of the battery pack assembly needs to pass through the pre-charge resistor before flowing to the high-voltage electrical device group. The presence of the pre-charge resistor significantly limits the peak value of the charging current, allowing the capacitive load to charge at a relatively smooth speed. In the normal charging mode and the high-voltage charging mode, before establishing an electrical connection with the charging pile, the charging circuit is pre-charged through the eighth relay 110 and the pre-charge resistor, so that the voltage difference between the battery pack assembly and the charging interface gradually decreases, avoiding the generation of inrush current when the third switch group is closed.

[0040] As the pre-charging process progresses, the voltage across the high-voltage electrical components in discharge mode and the voltage across the charging circuit in charging mode will gradually rise to near the output voltage of the battery pack assembly, for example, reaching more than 95% of the battery pack voltage. At this point, the pre-charging process can be considered complete, as the voltage difference between the two ends is very small, and even establishing a direct electrical connection will not generate a significant inrush current. After pre-charging is complete, the controller controls the ninth relay 111 to close and the eighth relay 110 to open, establishing a low-impedance direct conduction path. Current no longer flows through the pre-charging resistor to avoid unnecessary power loss and heat generation during normal operation.

[0041] By using the above-mentioned pre-charge and then direct connection control method, the safety of the electrical connection process can be guaranteed in discharge mode, normal charging mode and high voltage charging mode, while ensuring energy transmission efficiency during normal operation and effectively extending the service life of each electrical component.

[0042] In a preferred embodiment, the controller detects the charging enable signal sent by the charging pile to the BMS. When the charging enable signal is detected, it determines that the system has entered the charging state; when no charging enable signal is detected, it determines that the system has entered the discharging mode. After entering the charging state, the controller receives message information sent by the charging pile to the BMS. The message information includes the highest charging voltage parameter supported by the charging pile. The controller determines the charging mode based on the highest charging voltage parameter. When the highest charging voltage parameter is greater than or equal to a preset threshold, it determines that the system has entered the high-voltage charging mode; when the highest charging voltage parameter is less than the preset threshold, it determines that the system has entered the normal charging mode. The preset threshold is preferably 1000V.

[0043] Specifically, the controller is the Vehicle Control Unit (VCU), which obtains the charging pile's operational status information through communication with the Battery Management System (BMS). The charging enable signal is the A+ signal. After the vehicle establishes a physical connection with the charging pile, the charging pile sends the A+ signal to the BMS through the charging interface. The VCU monitors the presence of the A+ signal in real time through its communication interface with the BMS. When the A+ signal is detected, it indicates that the charging pile is ready and allows charging, at which point the VCU determines that the vehicle has entered the charging state. When the A+ signal is not detected, it means that the vehicle is not connected to the charging pile or the charging pile has not issued a charging enable signal, and the VCU determines that the vehicle has entered the discharging mode. At this time, the battery pack components need to supply power to the high-voltage electrical components to support the normal operation of the vehicle.

[0044] After the VCU determines that the charging state has been entered, the BMS continuously receives message information sent by the charging pile through the communication protocol. This message information contains various technical parameters of the charging pile, including the maximum charging voltage parameter supported by the charging pile. After obtaining the maximum charging voltage parameter through the BMS, the VCU compares it with a preset threshold to determine which charging mode should be adopted. When the maximum charging voltage parameter is greater than or equal to 1000V, it indicates that the charging pile has high-voltage charging capability and can support the battery pack assembly to be charged at 1200V. At this time, the VCU determines that the high-voltage charging mode has been entered, and accordingly controls the first and second switch groups to switch the battery pack assembly to the second connection state. When the maximum charging voltage parameter is less than 1000V, it indicates that the charging pile can only provide the normal charging voltage. At this time, the VCU determines that the normal charging mode has been entered, and the battery pack assembly remains in the first connection state and is charged at 800V.

[0045] In some preferred embodiments, the controller is electrically connected to each relay in the first switch group, the second switch group, the third switch group, and the pre-charging circuit, respectively, to control the on / off state of each relay according to the current operating mode.

[0046] In discharge mode, the controller needs to keep the battery pack assembly in the first connected state to supply power to the high-voltage electrical components. At this time, the controller closes, connecting the two second battery pack units 102 in series. Simultaneously, it controls the fourth relay 106 and the fifth relay 107 to close, establishing the first and second parallel branches. This connects the two first battery pack units 101 in parallel, which in turn connects with the series-connected second battery pack units 102, forming a first operating voltage of 800V. The controller also needs to disconnect the first relay 103 and the third relay 105 to prevent the formation of a high-voltage series branch, and disconnect the sixth relay 108 and the seventh relay 109 to physically isolate the battery pack assembly from the charging interface, ensuring electrical safety in discharge mode. Furthermore, the controller needs to control the switching of the eighth relay 110 and the ninth relay 111 according to the power demand of the high-voltage electrical components. Initially, the system is pre-charged via the eighth relay 110 and the pre-charging resistor. After pre-charging is complete, the eighth relay 110 is disconnected and the ninth relay 111 is closed to supply power to the high-voltage electrical components.

[0047] In normal charging mode, the controller also needs to keep the battery pack assembly in the first connected state. At this time, the controller keeps the second relay 104, the fourth relay 106, and the fifth relay 107 closed to maintain the parallel configuration of the battery pack assembly at 800V, while simultaneously opening the first relay 103 and the third relay 105 to prevent the formation of a high-voltage series branch. Furthermore, the controller also needs to close the sixth relay 108 and the seventh relay 109 in the third switch group to establish a charging circuit between the charging interface and the battery pack assembly, allowing the charging current output from the charging pile to flow into the battery pack assembly in the first connected state for charging. In normal charging mode, if the high-voltage electrical components in the vehicle require power, the VCU also needs to correspondingly control the on / off state of the eighth relay 110 and the ninth relay 111 to supply power to the high-voltage electrical components through the pre-charging circuit.

[0048] In high-voltage charging mode, the controller needs to switch the battery pack assembly to the second connection state to achieve 1200V high-voltage charging. At this time, the controller closes, connecting one first battery pack unit 101 and one second battery pack unit 102 in series to form a first series branch, and another first battery pack unit 101 and another second battery pack unit 102 in series to form a second series branch. These two series branches are then connected in parallel to form the second operating voltage of 1200V. The controller also needs to disconnect the second relay 104, the fourth relay 106, and the fifth relay 107 to break the series connection between the second battery pack units 102 and the parallel branch of the first battery pack unit 101, ensuring the battery pack assembly is in the correct high-voltage charging topology. Further, the controller closes the sixth relay 108 and the seventh relay 109 to establish an electrical connection between the charging interface and the battery pack assembly, achieving high-voltage fast charging. During high-voltage charging, if the high-voltage electrical components require power, the VCU will also control the switching of the eighth relay 110 and the ninth relay 111 according to the actual situation to supply power to the high-voltage electrical components.

[0049] Furthermore, this embodiment of the invention also provides a charging control method applied to the high-voltage fast charging system for electric commercial vehicles as described above. This method uses the vehicle control unit (VCU) to dynamically switch the connection status of battery pack components and intelligently select the charging mode. It includes the following steps: The VCU (Vehicle Control Unit) monitors the charging enable signal A+ sent from the charging pile to the BMS (Battery Management System) in real time via its communication interface. The presence or absence of this signal determines whether the vehicle should be in charging or discharging mode. When the charging enable signal A+ is detected, it indicates that the vehicle has established a physical connection with the charging pile and the charging pile allows charging. At this time, the VCU receives message information sent by the charging pile through the BMS. This message information contains the maximum charging voltage parameter supported by the charging pile. The VCU determines which charging mode should be adopted based on the comparison result of this parameter with a preset threshold of 1000V.

[0050] When the maximum charging voltage parameter is greater than or equal to the preset threshold of 1000V, it indicates that the charging pile has high-voltage charging capability and can support fast charging at a voltage level of 1200V. At this time, the VCU controls the second relay 104 in the first switch group to open, cutting off the series connection between the two second battery pack units 102. At the same time, it controls the first relay 103 and the third relay 105 to close, so that one first battery pack unit 101 and one second battery pack unit 102 are connected in series through the first relay 103 to form a first series branch, and another first battery pack unit 101 and another second battery pack unit 102 are connected in series through the third relay 105 to form a second series branch. The two series branches are connected in parallel to output a second working voltage of 1200V. At the same time, the VCU opens the fourth relay 106 and the fifth relay 107 in the second switch group to cut off the parallel branch of the first battery pack unit 101 to prevent the parallel path from interfering with the high-voltage charging topology. The VCU also needs to close the sixth relay 108 and the seventh relay 109 in the third switch group to establish a complete charging circuit between the charging interface and the battery pack assembly and execute charging in the high-voltage charging mode. During the entire high-voltage charging process, the high-voltage DC power output by the charging pile flows into the battery pack assembly in the second connection state through the charging interface and the third switch group, thereby achieving rapid charging of each battery pack unit.

[0051] When the maximum charging voltage parameter is less than the preset threshold of 1000V, it indicates that the charging pile only supports charging at the normal voltage level, and the battery pack assembly needs to be charged in the first connection state of 800V. At this time, the VCU controls the first relay 103 and the third relay 105 in the first switch group to open to prevent the formation of a high-voltage series branch, and at the same time controls the second relay 104 to close, so that the two second battery pack units 102 are connected in series. The VCU also needs to close the fourth relay 106 and the fifth relay 107 in the second switch group to establish the first parallel branch and the second parallel branch, so that the two first battery pack units 101 are connected in parallel, and then connected in parallel with the series-connected second battery pack unit 102 to form the first working voltage of 800V. At the same time, the VCU closes the sixth relay 108 and the seventh relay 109 in the third switch group to establish a charging circuit between the charging interface and the battery pack assembly, and executes charging in the normal charging mode. In the normal charging mode, the charging current output by the charging pile flows into the battery pack assembly in the first connection state through the charging interface, the third switch group and the second switch group to charge each battery pack unit.

[0052] When the charging enable signal A+ is not detected, it indicates that the vehicle is not connected to the charging pile or the charging pile has not issued a charging enable signal. In this case, the vehicle should enter discharge mode, where the battery pack assembly supplies power to the high-voltage electrical components to support normal vehicle operation. In discharge mode, the VCU controls the first relay 103 and the third relay 105 in the first switch group to open, and controls the second relay 104 to close, keeping the battery pack assembly in the first connected state. Simultaneously, the VCU closes the fourth relay 106 and the fifth relay 107 in the second switch group, establishing an electrical connection between the battery pack assembly and the pre-charging circuit, allowing the battery pack assembly to supply power to the high-voltage electrical components through the pre-charging circuit. Furthermore, the VCU must ensure that the sixth relay 108 and the seventh relay 109 in the third switch group are open, physically isolating the battery pack assembly from the charging interface to prevent high voltage at the charging interface during discharge mode, ensuring safe operation. When performing high-voltage power-on in discharge mode, the VCU needs to cooperate with the pre-charging circuit to perform pre-charging control on the high-voltage electrical components to avoid inrush current caused by direct power-on.

[0053] In a preferred embodiment, regardless of whether it is in high-voltage charging mode, normal charging mode, or discharging mode, when the high-voltage electrical device group needs to work, the VCU needs to control the power-on process through the pre-charging circuit to avoid the instantaneous large current from impacting the system. Therefore, the above-mentioned charging control method further includes the following steps: The VCU monitors the power demand signal of the high-voltage electrical components in real time. This signal can come from the driver's operation commands to equipment such as the air conditioner 112 and the PTC heater 113, or from the control commands automatically generated by the vehicle's automatic control system based on environmental parameters such as temperature and humidity.

[0054] When a power demand is detected in the high-voltage electrical component group, the VCU initiates the pre-charge control process: First, it controls the eighth relay 110 in the pre-charge circuit to close, while the ninth relay 111 remains open. At this time, the current output from the battery pack needs to pass through the pre-charge resistor before flowing to the high-voltage electrical component group. The current-limiting effect of the pre-charge resistor allows the capacitive load inside the high-voltage electrical component group to charge at a relatively slow speed, and its terminal voltage gradually increases. The VCU continuously monitors the terminal voltage of the high-voltage electrical component group. When the terminal voltage reaches a preset voltage threshold, such as more than 95% of the output voltage of the battery pack, it indicates that the pre-charge process has been completed. At this time, the voltage difference between the two ends of the high-voltage electrical component group and the two ends of the battery pack is very small.

[0055] After precharging is completed, the VCU controls the ninth relay 111 to close and the eighth relay 110 to open, establishing a low-impedance direct electrical connection between the battery pack assembly and the high-voltage electrical component group. The current no longer flows through the precharging resistor, avoiding power loss and heat generation in the precharging resistor during normal power supply. At this time, the entire power supply circuit is in normal working condition, and each device in the high-voltage electrical component group can work normally.

[0056] When the power demand of the high-voltage electrical components ends, such as when the driver turns off the air conditioner 112 or the vehicle control system determines that PTC heating is no longer needed, the VCU controls the ninth relay 111 to disconnect, cutting off the electrical connection between the battery pack assembly and the high-voltage electrical components, so that the system enters standby mode and prepares for the next power demand.

[0057] The high-voltage fast charging system and charging control method for electric commercial vehicles provided by this invention have the following significant advantages: First, by setting up the first switch group, the battery pack assembly can be flexibly switched between the first connection state and the second connection state. This allows the same battery pack assembly to work at an 800V voltage level to meet the needs of daily driving and regular charging, and at a 1200V voltage level for high-voltage fast charging. This significantly shortens charging time, improves vehicle operating efficiency, and avoids the increased cost and space occupation caused by the need to configure two independent battery systems in the traditional solution.

[0058] Secondly, by setting the second switch group, parallel connection between battery pack units and electrical connection with the pre-charging circuit are realized in the first connection state. This can not only provide stable power supply to the high-voltage electrical device group, but also form a complete charging circuit in the normal charging mode, thus improving the system's compatibility and applicability.

[0059] Furthermore, the pre-charging circuit configuration effectively avoids damage to the electrical system from the inrush current under various operating modes, extending the service life of relays, battery packs, and high-voltage electrical components, and improving the reliability and safety of the entire system.

[0060] Furthermore, the control method of the present invention is simple and clear. By detecting the charging enable signal and the charging pile message information, the working mode can be automatically determined and the corresponding relay control action can be executed, realizing intelligent switching of charging mode without manual intervention.

[0061] refer to Figure 2 and Figure 3 In one specific embodiment of the present invention, a high-voltage fast charging system for electric commercial vehicles and a charging control method thereof are also provided.

[0062] like Figure 2Preferably, the high-voltage fast charging system for electric commercial vehicles includes: four battery pack units, multiple relay switches, and a vehicle control unit (VCU). The rated voltages of the four battery pack units are 800V, 800V, 400V, and 400V, respectively. The multiple relay switches include K1, K2, K3, K4, K5, K6, K7, K8, and K9. Each relay connects the four battery pack units to the high-voltage electrical components and the charging pile through a specific connection method, which is the same as in the system embodiment described above and will not be repeated here. The high-voltage electrical components include on-board high-voltage electrical equipment such as air conditioners and PTC heaters. The vehicle control unit (VCU) is electrically connected to each relay and is used to control the on / off state of each relay according to the current operating mode, realizing the switching of battery pack components between different connection states and intelligent selection of charging modes.

[0063] like Figure 3 Preferably, based on the above system, the charging control method includes the following steps: Step S201: The vehicle is powered on, and the VCU wakes up the BMS after being powered on.

[0064] In step S202, the BMS determines whether it is in charging or discharging state at this time through the A+ signal. A+ is the signal sent by the charging pile to the BMS when charging. The presence of A+ indicates that the charging pile and the vehicle are successfully connected and charging can be started.

[0065] In step S203, when there is no A+ signal, it means that the vehicle is in discharge mode. The VCU sends a high-voltage command to the whole vehicle. At this time, K2 is closed to complete the parallel connection of the three 800V batteries. Then, K4 / K7 is closed and K1 / K3 is ensured to be open to complete the high-voltage power-on.

[0066] Step S204: Determine if there is a need to turn on the air conditioning and the cab heating. If so, the VCU sends a high-voltage pre-charge power-on command for the air conditioning and PTC circuits. If not, wait for the commands to turn on the air conditioning and the cab heating.

[0067] In step S205, K5 is closed to precharge the air conditioning and PTC high-voltage circuit.

[0068] Step S206: When the voltage at the back end of contactor K5 reaches 95% of the voltage at the front end, the pre-charging is completed. At this time, close K6 and open K5 to complete the power-on of the high-voltage electrical appliances.

[0069] Step S207: When the A+ signal is present, it indicates that the charging state has been entered.

[0070] In step S208, after entering the charging state, the charging pile sends a message to the BMS to specify the highest voltage currently supported by the charging pile.

[0071] Step S209: When the maximum voltage supported by the charging pile is greater than 1000V, it indicates that the high-voltage charging mode can be entered at this time.

[0072] In step S210, the VCU sends a high-voltage command. At this time, K1 / K3 closes, connecting the two 400V battery packs in series with the two 800V battery packs respectively. The battery packs then become two 1200V battery packs connected in parallel. At the same time, it is necessary to ensure that K2 is open to complete the 1200V charging high voltage power-on.

[0073] In step S211, contactors K8 / K9 close while ensuring contactors K4 / K7 open, thus starting the high-voltage charging mode.

[0074] In step S212, if there is a need to turn on the air conditioning or the driver's cab heating, proceed with steps S204 / S205 / S206.

[0075] Step S213: When the maximum charging voltage supported by the charging pile is less than 1000V, it indicates that only the normal charging mode can be entered at this time.

[0076] In step S214, the VCU sends a high-voltage command, K2 closes, realizing the parallel connection of three 800V battery packs, ensuring that K1 / K3 is open, and closing K4 / K7 to complete the 800V charging high voltage power-on.

[0077] In step S215, contactors K8 / K9 close to initiate normal charging.

[0078] Step S216: If there is a need to turn on the air conditioning or the driver's cab heating, proceed with steps S204 / S205 / S206.

[0079] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

Claims

1. A high-voltage fast charging system for electric commercial vehicles, characterized in that, include: - Charging interface, used to connect to a charging station to receive charging voltage; -High-voltage electrical components group; - A battery pack assembly, comprising two first battery pack units and two second battery pack units, wherein the voltage level of the first battery pack units is higher than that of the second battery pack units; - A first switch group and a second switch group are used to switch the series-parallel connection mode between the first battery pack unit and the second battery pack unit, so that the battery pack assembly forms a first working voltage in the first connection state and forms a second working voltage higher than the first working voltage in the second connection state. - A third switch group, used to connect the battery pack assembly to the charging interface; - A pre-charging circuit for connecting the battery pack assembly to the high-voltage electrical component group; - A controller, electrically connected to the first switch group, the third switch group and the second switch group, is used to control the on / off state of each switch group according to the working mode; In the discharge mode and normal charging mode, the first switch group and the second switch group control the battery pack assembly to be in the first connection state; in the high-voltage charging mode, the first switch group and the second switch group control the battery pack assembly to be in the second connection state.

2. The high-voltage fast charging system for electric commercial vehicles according to claim 1, characterized in that, The first battery pack unit includes a battery pack with a rated voltage of 800V, and the second battery pack unit includes a battery pack with a rated voltage of 400V. In the first connection state, the two first battery pack units are connected in parallel, and the two second battery pack units are connected in series and then connected in parallel with the first battery pack units in the parallel state. The first operating voltage is 800V. In the second connection state, one of the first battery pack units and one of the second battery pack units are connected in series to form a first series branch, and another of the first battery pack units and another of the second battery pack units are connected in series to form a second series branch. The first series branch and the second series branch are connected in parallel, and the second operating voltage is 1200V.

3. The high-voltage fast charging system for electric commercial vehicles according to claim 2, characterized in that, The first switch group includes a first relay, a second relay, and a third relay; The first relay is connected between a first battery pack unit and a second battery pack unit to control the series connection of the first series branch; The second relay is connected between the two second battery pack units and is used to control the series connection of the two second battery pack units; The third relay is connected between another first battery pack unit and another second battery pack unit to control the series connection of the second series branch.

4. The high-voltage fast charging system for electric commercial vehicles according to claim 3, characterized in that, The third switch group includes a sixth relay and a seventh relay; The sixth relay is disposed between the positive output terminal of the battery pack assembly and the positive terminal of the charging interface; The seventh relay is disposed between the negative output terminal of the battery pack assembly and the negative terminal of the charging interface.

5. The high-voltage fast charging system for electric commercial vehicles according to claim 4, characterized in that, The second switch group includes a fourth relay and a fifth relay; The fourth relay is disposed on a first parallel branch leading from a first battery pack unit, the first parallel branch being connected to the first end of the pre-charging circuit and the positive end of the charging interface respectively; The fifth relay is disposed on a second parallel branch leading from another first battery pack unit, the second parallel branch being connected to the second end of the pre-charging circuit and the negative terminal of the charging interface, respectively; The fourth and fifth relays are used to close in the first connection state so that the battery pack assembly supplies power to the high-voltage electrical device group through the pre-charging circuit, and forms a charging circuit with the third switch group in normal charging mode.

6. The high-voltage fast charging system for electric commercial vehicles according to claim 5, characterized in that, The pre-charging circuit includes an eighth relay and a ninth relay; The eighth relay is connected in series with the pre-charge resistor and then in parallel across the ninth relay to form a pre-charge branch. The high-voltage electrical device group includes multiple high-voltage electrical devices, which are connected in parallel to the output terminal of the pre-charging circuit; The eighth relay is used to close during the pre-charging stage to pre-charge the high-voltage electrical device group through the pre-charging resistor; after the pre-charging is completed, the eighth relay opens and the ninth relay closes to supply power to the high-voltage electrical device group normally.

7. The high-voltage fast charging system for electric commercial vehicles according to claim 6, characterized in that, The controller is electrically connected to each relay in the first switch group, the second switch group, the third switch group, and the pre-charging circuit, and is used to control the on / off state of each relay according to the current working mode. In the discharge mode, the controller controls the second, fourth, and fifth relays to close, controls the first, third, sixth, and seventh relays to open, and controls the eighth and ninth relays to open according to the power demand of the high-voltage electrical device group; In the normal charging mode, the controller controls the second relay, the sixth relay, the seventh relay, the fourth relay and the fifth relay to close, controls the first relay and the third relay to open, and controls the eighth relay and the ninth relay to open and close according to the power demand of the high-voltage electrical device group; In the high-voltage charging mode, the controller controls the first, third, sixth, and seventh relays to close, controls the second, fourth, and fifth relays to open, and controls the eighth and ninth relays to open and close according to the power demand of the high-voltage electrical device group.

8. The high-voltage fast charging system for electric commercial vehicles according to claim 7, characterized in that, The controller is also used for: The system detects the charging enable signal sent from the charging pile to the BMS. When the charging enable signal is detected, it determines that the system has entered the charging state. When the charging enable signal is not detected, it determines that the system has entered the discharging mode. After entering the charging state, the system receives message information sent by the charging pile, which includes the highest charging voltage parameter supported by the charging pile. The charging mode is determined based on the highest charging voltage parameter. When the highest charging voltage parameter is greater than or equal to a preset threshold, it is determined to enter the high-voltage charging mode; when the highest charging voltage parameter is less than the preset threshold, it is determined to enter the normal charging mode; wherein, the preset threshold is 1000V.

9. A charging control method, applied to the high-voltage fast charging system for electric commercial vehicles as described in claim 8, characterized in that, Includes the following steps: Detect the charging enable signal sent from the charging pile to the BMS; When the charging enable signal is detected, the system receives the message information sent by the charging pile and determines the charging mode based on the highest charging voltage parameter in the message information. When the maximum charging voltage parameter is greater than or equal to a preset threshold, the second relay in the first switch group is opened, and the first and third relays are closed, so that the two first battery pack units are connected in series with the two second battery pack units respectively, the second switch group is opened and the third switch group is closed, and charging in high-voltage charging mode is performed. When the maximum charging voltage parameter is less than the preset threshold, the first and third relays in the first switch group are opened and the second relay is closed. The second switch group is closed so that the two second battery pack units are connected in series and then connected in parallel with the two first battery pack units. The third switch group is closed to perform charging in normal charging mode. When the charging enable signal is not detected, the first and third relays in the first switch group are opened and the second relay is closed, closing the second switch group, so that the two second battery pack units are connected in series and then connected in parallel with the two first battery pack units to perform high-voltage power-on in discharge mode.

10. The charging control method according to claim 9, characterized in that, Also includes: In the high-voltage charging mode, the normal charging mode, or the discharging mode, the power demand signal of the high-voltage electrical device group is detected in real time. When a power demand is detected in the high-voltage electrical device group, a pre-charging control process is executed: First, control the eighth relay to close and the ninth relay to remain open, and precharge the high-voltage electrical device group through the pre-charging resistor until the terminal voltage of the high-voltage electrical device group reaches the preset voltage threshold. Then, the ninth relay is controlled to close and the eighth relay is opened to establish a direct electrical connection between the battery pack assembly and the high-voltage electrical component group. When the power demand of the high-voltage electrical device group ends, the ninth relay is controlled to disconnect.

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