Bidirectional DCDC system integrated with low-voltage battery and vehicle thereof

Abstract

The invention discloses a bidirectional DCDC system integrated with a low-voltage battery. The bidirectional DCDC system comprises a low-voltage battery module, a bidirectional DCDC conversion module and a BMS battery management system. The low-voltage battery module is used for supplying power to a low-voltage vehicle-mounted electric appliance and a vehicle; the bidirectional DCDC conversion module adopts an isolated DCDC and is used for reducing or boosting the voltage output by the low-voltage battery module, and the bidirectional DCDC conversion module is connected with the low-voltage battery module; the BMS battery management system is used for controlling the bidirectional DCDC conversion module to execute any one of the buck instruction and the boost instruction. The invention discloses a vehicle applying the bidirectional DCDC system. According to the invention, the bidirectional DCDC conversion module and the low-voltage battery module are integrated, so that the overall occupied space is small; the bidirectional DCDC conversion module is controlled by the BMS battery management system, so that the bidirectional DCDC system and the vehicle applying the system have the function of switching two working modes of voltage boosting and voltage reducing which do not exist at the same time, and high-voltage and low-voltage conversion can be rapidly and automatically switched.

Description

Technical Field

[0001] The present invention relates to the technical field of battery power supply, and in particular to a bidirectional DCDC system integrating a low-voltage battery and a vehicle thereof. Background Art

[0002] The DC / DC module is a key component of a pure electric vehicle's electrical system. Its primary function is to convert high-voltage DC power into low-voltage power to power the vehicle's low-voltage electrical appliances. Currently, the DC / DC module and low-voltage battery pack typically exist as separate modules. While there is some interdependence at the control level, overall control is primarily implemented by the vehicle control unit (VCU). This independent module design approach has significant drawbacks. Firstly, each independent module takes up considerable space within the vehicle, hindering the optimal layout of the interior. Secondly, the control logic is complex, increasing the difficulty and cost of controlling the vehicle's electrical system.

[0003] Existing DC / DC modules have relatively simple functions, primarily focusing on converting DC high voltage to low voltage. Some modules also have low voltage to high voltage capabilities, but these still have limitations in practical applications. For example, during vehicle system operation, if there is a scenario where the battery voltage needs to be increased to meet the needs of specific high-power equipment, while also needing to convert high voltage to low voltage to power conventional low-voltage electrical appliances, existing technical solutions would require two DC / CDC modules. While this meets the specific power requirements of different systems to a certain extent and improves system stability and safety, it essentially still solves functional requirements by increasing the number of DC / CDC modules. This not only increases the number of components, making component management more difficult, but also makes the control logic more complicated, further increasing system complexity and the risk of failure. Summary of the Invention

[0004] To address the existing issues of separate DCDC modules and low-voltage battery packs, which occupy large spaces and have single functions, requiring multiple modules to coordinate with each other in the vehicle system, further increasing the difficulty of component management and control complexity, the present invention proposes a bidirectional DCDC system with integrated low-voltage batteries.

[0005] The specific technical solution is as follows: a bidirectional DCDC system with integrated low-voltage battery, including: a low-voltage battery module, a bidirectional DCDC conversion module and a BMS battery management system;

[0006] Low-voltage battery module: used to power low-voltage on-board electrical appliances and vehicles;

[0007] Bidirectional DCDC conversion module: uses isolated DCDC to step down or step up the voltage output by the low-voltage battery module. The bidirectional DCDC conversion module is connected to the low-voltage battery module.

[0008] BMS battery management system: used to control the bidirectional DCDC conversion module to execute either step-down or step-up instructions.

[0009] Furthermore, the bidirectional DCDC conversion module includes a DCDC module control switch, which is connected to the BMS battery management system and is used to switch the BMS battery management system's boost or buck instructions.

[0010] Furthermore, the BMS battery management system includes a state protection module, which is connected to the DCDC module control switch and is used to cut off the BMS battery management system from executing the boost instruction.

[0011] Furthermore, the BMS battery management system includes an abnormality monitoring module for monitoring the voltage, current, temperature and voltage difference of the low-voltage battery module.

[0012] Furthermore, the voltage of the low-voltage battery in the low-voltage battery module is 24~60V.

[0013] Furthermore, the voltage of the low-voltage battery in the low-voltage battery module is 48 V.

[0014] A vehicle includes a bidirectional DCDC system integrated with a low-voltage battery, a vehicle control unit (VCU), and a high-voltage battery system. The high-voltage battery system is connected to a low-voltage battery module via a bidirectional DCDC conversion module, and the vehicle control unit (VCU) is communicatively connected to a BMS battery management system.

[0015] Furthermore, it also includes a low-voltage power system, which is connected to the bidirectional DCDC conversion module and includes low-voltage on-board electrical appliances.

[0016] Furthermore, the vehicle is either a hybrid electric vehicle or a pure electric vehicle.

[0017] The above technical solution has the following advantages or technical effects:

[0018] 1. This invention utilizes an integrated low-voltage battery and DCDC module solution, enabling multi-module collaborative management through a BMS master control system. Compared to traditional multi-DCDC module architectures, this design effectively addresses the high space utilization of new energy vehicle electronic systems, improving energy transmission efficiency while significantly reducing connector failure rates and extending maintenance cycles.

[0019] 2. This invention adopts a BMS-directed DC-DC control mode, breaking away from the traditional VCU-mediated control paradigm. By building a control bus, the original three-level communication (BMS→VCU→DCDC) is simplified to a single-level command transmission, effectively avoiding the risk of signal delays in multi-system coordination and being particularly suitable for frequent charging and discharging scenarios.

[0020] 3. The BMS of this invention participates in VCU communication control and can consider both battery status and DCDC status (for example, if the SOC is lower than 50%, it will consider switching to high voltage). After comprehensively evaluating the battery status, it communicates with the VCU, making information transmission more accurate.

[0021] 4. The DCDC system of the present invention has a bidirectional conversion function and can switch between voltages higher than (800V) or lower than (12V) its own voltage. It has a large step-up / step-down ratio, a wider range of applications, and more convenient overall operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall system framework of the present invention;

[0023] Figure 2 It is a schematic diagram of the vehicle system framework of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] like Figure 1 As shown, a bidirectional DCDC system integrated with a low-voltage battery includes: a low-voltage battery module, a bidirectional DCDC conversion module and a BMS battery management system;

[0027] Low-voltage battery module: used to power low-voltage on-board electrical appliances and vehicles;

[0028] Bidirectional DCDC conversion module: uses isolated DCDC to step down or step up the voltage output by the low-voltage battery module. The bidirectional DCDC conversion module is connected to the low-voltage battery module.

[0029] BMS battery management system: used to control the bidirectional DCDC conversion module to execute either step-down or step-up instructions.

[0030] The above modules and systems are connected through necessary electrical and communication connections, which do not belong to the main content of this application and will not be described in detail here.

[0031] The primary function of existing DCDC modules (Direct Current Converters) is to convert the high-voltage powertrain output into low-voltage power to meet the power needs of low-voltage onboard electrical devices. Their electrical architecture is typically independent of the low-voltage battery pack. While the two collaborate on vehicle energy management, the control logic remains centrally coordinated by the vehicle control unit (VCU). While this distributed layout offers modular advantages, it also results in a high system footprint and significantly increases the complexity of the multi-module coordinated control strategy.

[0032] Current DC-DC module designs are unidirectional, with mainstream products supporting only single-directional voltage conversion: high-voltage to low-voltage or low-voltage boost. When a vehicle system requires bidirectional voltage conversion (for example, a battery pack that requires both boosted output and buck charging), a two-module solution must be employed. This technical approach not only increases hardware management but also requires control strategies to coordinate timing matching, power allocation, and fault diagnosis between the two modules, exponentially increasing system complexity.

[0033] Therefore, this application proposes a bidirectional conversion DCDC system integrated with a low-voltage battery. By integrating the bidirectional DCDC conversion module and the low-voltage battery module, the overall space occupied is small; the bidirectional DCDC conversion module is controlled by the BMS battery management system (Battery Management System), so that the entire system has the function of switching between the two working modes of boost and buck that exist at the same time. The high-voltage and low-voltage conversion can be switched automatically without the need for a VCU. The conversion strategy is simple and the processing speed is faster, which facilitates subsequent maintenance.

[0034] The low-voltage battery module provides power for low-voltage on-board electronic appliances, such as 12V / 14V low-voltage on-board appliances; provides auxiliary power for new energy vehicles (including hybrid vehicles); or converts to high-voltage electricity to provide a power source for the vehicle in an emergency. The low-voltage battery voltage in the low-voltage battery module ranges from 24 to 60 V, and preferably, the low-voltage battery voltage in the low-voltage battery module is 48 V. To perform the function of rapidly converting to high-voltage electricity, the low-voltage battery has a built-in cell with a capacity of 16 Ah or more, preferably, a cell with a capacity of 20 Ah or more, so that the low-voltage battery voltage can be quickly converted to high voltage when necessary, quickly increasing power.

[0035] The bidirectional DC-DC converter module switches between low voltage (12 V / 14 V for conventional onboard electrical components) and high voltage (rated voltage of the high-voltage system is 800 V). The low-voltage battery module connected to the bidirectional DC-DC converter module is preferably rated at 48 V. Due to the wide voltage conversion range, the DC-DC converter requires a large step-up / step-down ratio. An isolated DC-DC converter is preferably used, converting DC to AC via an inverter, then stepping up and down the AC coil, and finally converting the AC to DC via a rectifier. The bidirectional DC-DC converter module includes a DC-DC module control switch, which connects to the battery management system (BMS). The module has two electrical connection ports, one for connecting to the low-voltage battery system (48 V) and the other for connecting to the high-voltage distribution box, which is connected to the high-voltage system and the motor. The DC-DC module control switch includes a low-voltage terminal and a high-voltage terminal, corresponding to the low-voltage battery system and the high-voltage distribution box, respectively.

[0036] The bidirectional DCDC conversion module is controlled by the BMS battery management system, so that the bidirectional DCDC system in this application includes two operating modes:

[0037] Operating Mode 1: The DCDC system primarily provides a step-down function, converting the 48V low-voltage battery system voltage output to a lower voltage (12V / 14V) through DCDC and charging the low-voltage battery. Since the low-voltage battery primarily supplies auxiliary electrical devices within the vehicle, its charge level gradually decreases, requiring the high-voltage battery to recharge the low-voltage system.

[0038] Working mode 2: The DCDC system mainly provides a boost function, that is, converting the low voltage output of the low-voltage battery into a high voltage through DCDC, which is used to power the high-voltage battery system in an emergency.

[0039] The two working modes cannot exist at the same time.

[0040] The BMS includes a state protection module, which is connected to the DCDC module control switch to implement the battery protection control strategy and prevent the BMS from executing the boost command. When the BMS detects a low SOC of the low-voltage battery module, such as below 50%, the bidirectional DCDC conversion module will not be triggered to execute the boost command, even if conversion to a high-voltage auxiliary power signal is required.

[0041] The BMS battery management system includes an abnormality monitoring module, which is used to monitor the voltage, current, temperature and voltage difference of the low-voltage battery module. When the BMS battery management system detects an abnormality in the status of the low-voltage battery module, the BMS battery management system will upload the abnormality to the cloud and issue an alarm to ensure stable operation of the system.

[0042] Example 2

[0043] like Figure 2 As shown, a vehicle includes a bidirectional DCDC system with an integrated low-voltage battery, a vehicle control unit VCU and a high-voltage battery system. The high-voltage battery system is connected to the low-voltage battery module through a bidirectional DCDC conversion module, and the vehicle control unit VCU is communicatively connected to the BMS battery management system.

[0044] The system also includes a low-voltage power system, which is connected to the bidirectional DC-DC converter module and includes low-voltage onboard electrical appliances. The vehicle control unit (VCU) communicates with the high-voltage battery system and the low-voltage power system.

[0045] The high-voltage battery system is a power battery, and the vehicle is either a hybrid vehicle or a pure electric vehicle. The aforementioned modules, systems, and units are connected through necessary electrical and communication connections and are provided with corresponding mechanical connection structures. This content is not part of the main content of this application and will not be described in detail here.

[0046] The BMS (Battery Management System) monitors the status of the vehicle's medium- and low-voltage battery modules and the operating status of the bidirectional DC-DC converter module. It also controls the DC-DC converter module, including converting the voltages of high- and low-voltage devices. The bidirectional DC-DC converter module converts 48V to either high- or low-voltage devices, making it a single-mode option. Operating modes one and two cannot coexist; the specific operating mode depends on the vehicle and battery system's control status.

[0047] The specific control strategies in the vehicle are as follows:

[0048] The BMS battery management system monitors the status of the low-voltage battery module and communicates synchronously with the vehicle control unit VCU;

[0049] When the BMS battery management system receives a signal that needs to be supplied to a low-voltage electrical device (12V / 14V), it triggers the DCDC module control switch to the low-voltage end position and connects to the low-voltage electrical device. Then, the bidirectional DCDC conversion module converts the voltage in the low-voltage battery module into a lower voltage for use by the low-voltage electrical device.

[0050] When the BMS battery management system receives a signal that it needs to provide energy to the high-voltage battery system, it triggers the DCDC module control switch to the high-voltage end position and connects to the high-voltage battery system. The bidirectional DCDC conversion module then converts the voltage in the low-voltage battery module into high-voltage electrical energy.

[0051] When the BMS battery management system monitors that the SOC of the low-voltage battery module is low, such as below 50%, even if the vehicle control unit VCU sends a signal that it needs to be converted to high-voltage auxiliary power, it will not trigger the bidirectional DCDC conversion module to execute the boost instruction.

[0052] When the BMS battery management system detects an abnormality in the low-voltage battery module status, the BMS battery management system will report it to the vehicle control unit VCU to ensure the stability of the bidirectional DCDC system of the entire integrated low-voltage battery.

[0053] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A bidirectional DCDC system with integrated low-voltage battery, characterized in that: include: Low-voltage battery module, bidirectional DCDC conversion module and BMS battery management system; Low-voltage battery module: used to power low-voltage on-board electrical appliances and vehicles; Bidirectional DCDC conversion module: uses isolated DCDC to step down or step up the voltage output by the low-voltage battery module. The bidirectional DCDC conversion module is connected to the low-voltage battery module. BMS battery management system: used to control the bidirectional DCDC conversion module to execute either step-down or step-up instructions.

2. The bidirectional DCDC system with integrated low-voltage battery according to claim 1, characterized in that: The bidirectional DCDC conversion module includes a DCDC module control switch, which is connected to the BMS battery management system and is used to switch the BMS battery management system's boost or buck instructions.

3. The bidirectional DCDC system with integrated low-voltage battery according to claim 2, characterized in that: The BMS battery management system includes a state protection module, which is connected to the DCDC module control switch and is used to cut off the BMS battery management system from executing the boost instruction.

4. The bidirectional DCDC system with integrated low-voltage battery according to claim 1, characterized in that: The BMS battery management system includes an abnormality monitoring module for monitoring the voltage, current, temperature and voltage difference of the low-voltage battery module.

5. The bidirectional DCDC system with integrated low-voltage battery according to claim 1, characterized in that: The voltage of the low-voltage battery in the low-voltage battery module is 24~60V.

6. The bidirectional DCDC system integrated with a low-voltage battery according to claim 5, characterized in that: The voltage of the low-voltage battery in the low-voltage battery module is 48 V.

7. A vehicle, characterized in that: It comprises a bidirectional DCDC system with an integrated low-voltage battery as described in any one of claims 1 to 6, a vehicle control unit VCU and a high-voltage battery system, the high-voltage battery system is connected to the low-voltage battery module through a bidirectional DCDC conversion module, and the vehicle control unit VCU is communicatively connected to the BMS battery management system.

8. A vehicle according to claim 7, characterized in that: It also includes a low-voltage power system, which is connected to the bidirectional DCDC conversion module and includes low-voltage on-board electrical appliances.

9. A vehicle according to claim 7, characterized in that: The vehicle is either a hybrid electric vehicle or a pure electric vehicle.

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