Integrated functional circuit of battery management system, control method of integrated functional circuit, battery management system and electric equipment

Abstract

The invention discloses an integrated functional circuit of a battery management system, a control method of the integrated functional circuit of the battery management system, the battery management system and electric equipment, and the integrated functional circuit of the battery management system comprises an electric energy conversion module and a switching network which are arranged between a battery pack and an external load, the electric energy conversion module is provided with a first port connected with the positive output end of the battery pack and a second port selectively connected with the negative output end of the battery pack or the positive input end of an external load through a switching network; the control module is connected with the electric energy conversion module and the switching network. The control module is configured to control the switch network to connect the electric energy conversion module between the battery pack and the positive input end of an external load and control the electric energy conversion module to output pre-charging current in the pre-charging stage, and control the switch network to connect the electric energy conversion module between the positive output end and the negative output end of the battery pack in the battery heating stage. And the electric energy conversion module is controlled to convert the direct-current output voltage of the battery into alternating current.

Description

Integrated functional circuits and control methods for battery management systems, battery management systems and electrical equipment Technical Field

[0001] This invention relates to the field of battery system technology, and in particular to an integrated functional circuit and control method for a battery management system, a battery management system, and electrical equipment. Background Technology

[0002] Current battery systems typically employ separate designs for pre-charging circuits and cryogenic heating systems. Each function has its own inherent technical limitations, making it difficult to meet the requirements of modern battery systems for high efficiency, compactness, and economy.

[0003] In existing pre-charging circuits, the pre-charging resistor generates significant heat when subjected to instantaneous high current, which may lead to resistor erosion or even failure over long-term use. Furthermore, once the pre-charging process is complete, the circuit remains idle, resulting in wasted hardware resources. Existing heating solutions typically require independent heating elements and drive circuits, heating the battery from the outside in through resistive heating. This heating method suffers from "thermal hysteresis," meaning uneven heating, low efficiency, and poor reliability, and requires independent hardware circuitry, increasing system complexity, size, and cost.

[0004] In summary, current technology lacks a solution that can completely reuse hardware circuitry and highly integrate pre-charging, heating, and even charging functions. Such a solution would require implementing multiple functions using a single hardware setup, reducing system cost, size, and complexity. Summary of the Invention

[0005] This invention proposes an integrated functional circuit for a battery management system, comprising: a power conversion module, a switching network, and a control module; the power conversion module and the switching network are disposed between a battery pack and an external load, wherein the power conversion module has a first port connected to the positive output terminal of the battery pack, and a second port selectively connected to the negative output terminal of the battery pack or the positive input terminal of the external load through the switching network; the control module is connected to both the power conversion module and the switching network; wherein the control module is configured to: during the pre-charging phase, control the switching network to connect the power conversion module between the battery pack and the positive input terminal of the external load, and control the power conversion module to output a pre-charging current to pre-charge the bus capacitor within the external load; during the battery heating phase, control the switching network to connect the power conversion module between the positive and negative output terminals of the battery pack, and control the power conversion module to convert the DC output voltage of the battery into AC power before injecting it into the battery pack.

[0006] Optionally, the power conversion module is a bidirectional Buck-Boost converter or an H-bridge inverter circuit.

[0007] Optionally, the switch network includes: a first controlled switch connected in series between the positive output terminal of the battery pack and the positive input terminal of the external load; a second controlled switch connected in series between the negative terminal of the battery pack and the negative input terminal of the external load; a third controlled switch connected in series between the second port of the power conversion module and the positive input terminal of the external load; and a fourth controlled switch connected in series between the second port of the power conversion module and the negative terminal of the battery pack.

[0008] Optionally, the frequency of the alternating current is set to a preset value that matches the characteristic frequency of the internal resistance of the battery pack at low temperatures.

[0009] Optionally, the integrated functional circuit of the battery management system further includes: a current detection unit; the current detection unit is connected to the control module and is used to detect the current value flowing out of the positive output terminal of the battery pack and output the sampled current value to the control module; the control module is also used to control the pre-charge current value output by the power conversion module according to the sampled current value.

[0010] This invention also proposes an integrated functional circuit control method for a battery management system, applied to the integrated functional circuit of the battery management system; the integrated functional circuit control method includes: in response to a system startup command, acquiring battery pack status parameters and the bus voltage of the external load; determining the operating stage based on the battery pack status parameters and the bus voltage; if in the pre-charging stage, controlling the switch network to connect the power conversion module between the battery pack and the positive input terminal of the external load, and controlling the power conversion module to output a pre-charging current to pre-charge the bus capacitor in the external load; if in the battery heating stage, controlling the switch network to connect the power conversion module between the positive and negative output terminals of the battery pack, and controlling the power conversion module to convert the DC output voltage of the battery into AC power and inject it into the battery pack; if in the normal operating stage, controlling the switch network to connect the battery pack and the external load.

[0011] Optionally, the control power conversion module outputs a pre-charging current to pre-charge the bus capacitor in the external load, including: monitoring the bus voltage of the external load; dynamically adjusting the pre-charging current according to the real-time difference between the bus voltage and the battery pack voltage; and determining that pre-charging is complete when the real-time difference drops below a first preset threshold.

[0012] Optionally, the control power conversion module converts the DC output voltage of the battery into AC power, including: acquiring the real-time temperature and battery parameters of the battery pack; based on the real-time temperature and battery parameters, querying a preset mapping relationship to determine at least one target parameter among the current optimal heating current amplitude, frequency, and waveform; and controlling the power conversion module according to the target parameter so that the alternating current output by the power conversion module matches the target parameter.

[0013] The present invention also proposes a battery management system, including: a battery pack, a load interface, and an integrated functional circuit of the battery management system.

[0014] The present invention also proposes an electrical device including the battery management system.

[0015] This invention discloses an integrated functional circuit for a battery management system, a control method for the integrated functional circuit for a battery management system, a battery management system, and an electrical device. The integrated functional circuit for the battery management system includes: a power conversion module, a switching network, and a control module. The power conversion module and the switching network are disposed between a battery pack and an external load. The power conversion module has a first port connected to the positive output terminal of the battery pack and a second port selectively connected to the negative output terminal of the battery pack or the positive input terminal of the external load through the switching network. The control module is connected to both the power conversion module and the switching network. The control module is configured to: during the pre-charging phase, control the switching network to connect the power conversion module between the battery pack and the positive input terminal of the external load, and control the power conversion module to output a pre-charging current to pre-charge the bus capacitor within the external load; during the battery heating phase, control the switching network to connect the power conversion module between the positive and negative output terminals of the battery pack, and control the power conversion module to convert the DC output voltage of the battery into AC power before injecting it into the battery pack. This invention achieves three functions—pre-charging, battery heating, and normal power supply—through the reconfiguration of the same power conversion module and switching network via control logic. It replaces the separately set pre-charging resistor and heater in traditional solutions, significantly reducing the number of components, system size, and cost. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 is a schematic diagram of the structure of an embodiment of the integrated functional circuit of the battery management system of the present invention; Figure 2 is a schematic diagram of the structure of another embodiment of the integrated functional circuit of the battery management system of the present invention; Figure 3 is a schematic diagram of the steps of an embodiment of the control method of the integrated functional circuit of the battery management system of the present invention; Figure 4 is a schematic diagram of the steps of another embodiment of the control method of the integrated functional circuit of the battery management system of the present invention; Figure 5 is a schematic diagram of the steps of yet another embodiment of the control method of the integrated functional circuit of the battery management system of the present invention.

[0018] Explanation of icon numbers:

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0024] This invention provides an integrated functional circuit for a battery management system, comprising: a power conversion module 10, a switching network 20, and a control module 30; the power conversion module 10 and the switching network 20 are disposed between a battery pack and an external load, wherein the power conversion module 10 has a first port connected to the positive output terminal of the battery pack, and a second port selectively connected to the negative output terminal of the battery pack or the positive input terminal of the external load through the switching network 20; the control module 30 is connected to both the power conversion module 10 and the switching network 20; wherein the control module 30 is configured to: in the pre-charging stage, control the switching network 20 to connect the power conversion module 10 between the battery pack and the positive input terminal of the external load, and control the power conversion module 10 to output a pre-charging current to pre-charge the bus capacitor in the external load; in the battery heating stage, control the switching network 20 to connect the power conversion module 10 between the positive and negative output terminals of the battery pack, and control the power conversion module 10 to convert the DC output voltage of the battery into AC power and inject it into the battery pack.

[0025] It should be explained that, as shown in Figure 1, the power conversion module 10 is used to convert and transmit electrical energy, and it has a first port P1 and a second port P2. The first port P1 is connected to the positive output terminal B+ of the battery pack. The second port P2 is selectively connected to the negative output terminal B- of the battery pack or the positive input terminal L+ of an external load through the switch network 20.

[0026] In a preferred embodiment, the power conversion module 10 is a bidirectional Buck-Boost converter. The converter includes an inductor, a first switching transistor, a second switching transistor, and a capacitor. One end of the inductor is connected to a first port P1, and the other end is connected to the common node of the first and second switching transistors. The other end of the first switching transistor is connected to a second port P2, and the other end of the second switching transistor is grounded or connected to a reference potential. The capacitor is connected between the second port P2 and ground. By controlling the on / off state of the first and second switching transistors, the circuit can switch between Buck mode, Boost mode, and AC output mode.

[0027] The switch network 20 includes multiple controlled switches for reconfiguring current paths at different operating stages.

[0028] In a specific example, as shown in Figure 2, the switch network 20 includes: a first controlled switch K1, connected in series between the positive output terminal B+ of the battery pack and the positive input terminal L+ of the external load; a second controlled switch K2, connected in series between the negative output terminal B- of the battery pack and the negative input terminal L- of the external load; a third controlled switch K3, connected in series between the second port P2 of the power conversion module 10 and the positive input terminal L+ of the external load; and a fourth controlled switch K4, connected in series between the second port P2 of the power conversion module 10 and the negative output terminal B- of the battery pack.

[0029] The control module 30 is electrically connected to the power conversion module 10 and the switch network 20, respectively, and is used to collect system status signals and output corresponding control signals to coordinate the operation of each module. The control module 30 is configured to perform the following operations: When the system is powered on or an external load is connected, the control module 30 detects the bus voltage of the external load. If the voltage is lower than a certain threshold of the battery pack voltage, it determines that the pre-charging stage has begun. At this time, the control module 30 controls the state of the switch network 20 as follows: K1 open, K2 closed, K3 closed, and K4 open. At the same time, the control module 30 controls the power conversion module 10 to operate in Buck mode, making it a controlled current source, drawing power from the battery pack, and charging the bus capacitor of the external load with a controllable current. During the charging process, the control module 30 monitors the bus voltage in real time and dynamically adjusts the output current according to the voltage changes until the bus voltage approaches the battery pack voltage, at which point the pre-charging is complete.

[0030] When the control module 30 detects that the battery pack temperature is lower than the preset heating start-up temperature threshold, it determines that the battery heating stage has begun. At this time, the control module 30 controls the state of the switch network 20 as follows: K1 is open, K2 is open, K3 is open, and K4 is closed. Simultaneously, the power conversion module 10 is controlled to operate in AC output mode, specifically by controlling the first and second switching transistors to be driven by complementary pulse width modulation (PWM) signals, thereby generating an alternating current between the positive and negative output terminals of the battery pack. This current flows through the inside of the battery pack, utilizing the battery's internal resistance to generate heat, achieving internal self-heating of the battery. During the heating process, the control module 30 continuously monitors the battery temperature until the temperature rises to the preset heating stop threshold, at which point the heating mode is exited.

[0031] When pre-charging and battery heating are not required, the system is in normal operation. The control module 30 controls the state of the switch network 20 as follows: K1 closed, K2 closed, K3 open, and K4 open. At this time, the power conversion module 10 is bypassed, and a direct low-impedance connection is formed between the battery pack and the external load, achieving efficient energy transfer.

[0032] In another embodiment of the present invention, the power conversion module 10 is an H-bridge inverter circuit. This circuit includes a bridge arm composed of four switching transistors and a filter inductor. By controlling the on / off sequence of the four switching transistors, this circuit can also achieve DC-to-AC conversion and has bidirectional energy flow capability.

[0033] In this embodiment, during the battery heating stage, the control module 30 controls the H-bridge inverter circuit to output AC power of a specific frequency and waveform, which is then injected into the battery pack for heating. The control logic for its pre-charging and normal operation stages is similar to that of the embodiments described above, both involving path reconstruction via the switch network 20 and control of the power conversion module 10 to operate in the corresponding modes.

[0034] This invention discloses an integrated functional circuit for a battery management system, comprising: a power conversion module 10, a switching network 20, and a control module 30; the power conversion module 10 and the switching network 20 are disposed between a battery pack and an external load, wherein the power conversion module 10 has a first port connected to the positive output terminal of the battery pack, and a second port selectively connected to the negative output terminal of the battery pack or the positive input terminal of the external load through the switching network 20; the control module 30 is connected to both the power conversion module 10 and the switching network 20; wherein the control module 30 is configured to: in the pre-charging stage, control the switching network 20 to connect the power conversion module 10 between the battery pack and the positive input terminal of the external load, and control the power conversion module 10 to output a pre-charging current to pre-charge the bus capacitor within the external load; in the battery heating stage, control the switching network 20 to connect the power conversion module 10 between the positive and negative output terminals of the battery pack, and control the power conversion module 10 to convert the DC output voltage of the battery into AC power and inject it into the battery pack. This invention achieves three functions—pre-charging, battery heating, and normal power supply—through the same set of power conversion module 10 and switch network 20 reconfigured by control logic. It replaces the independently set pre-charging resistor and heater in the traditional solution, significantly reducing the number of components, system size, and cost.

[0035] In one example, the switch network 20 includes: a first controlled switch connected in series between the positive output terminal of the battery pack and the positive input terminal of the external load; a second controlled switch connected in series between the negative terminal of the battery pack and the negative input terminal of the external load; a third controlled switch connected in series between the second port of the power conversion module 10 and the positive input terminal of the external load; and a fourth controlled switch connected in series between the second port of the power conversion module 10 and the negative terminal of the battery pack.

[0036] It should be explained that the switch network 20 is connected between the battery pack (positive output terminal B+, negative output terminal B-), the power conversion module 10 (second port P2) and the external load (positive input terminal L+, negative input terminal L-) to reconstruct the energy path, which is the key to realizing function reuse.

[0037] Specifically, the switching network 20 includes: a first controlled switch K1, whose main current path is connected in series between the positive output terminal B+ of the battery pack and the positive input terminal L+ of the external load. When K1 is closed, a direct main path is established from the positive terminal of the battery pack to the positive terminal of the load.

[0038] The second controlled switch K2 has its main current path connected in series between the negative output terminal B- of the battery pack and the negative input terminal L- of the external load. When K2 is closed, a direct main path is established from the negative terminal of the battery pack to the negative terminal of the load. When K1 and K2 are closed simultaneously, a direct working loop is formed between the battery pack and the external load.

[0039] The third controlled switch K3 has its main current path connected in series between the second port P2 of the power conversion module 10 and the positive input terminal L+ of the external load. This switch is used to direct the output of the power conversion module 10 to the bus capacitor of the external load during the pre-charging phase.

[0040] The fourth controlled switch K4 has its main current path connected in series between the second port P2 of the power conversion module 10 and the negative output terminal B- of the battery pack. This switch is used to form a closed loop through the battery pack by the output of the power conversion module 10 during the battery heating stage.

[0041] In a preferred embodiment, the first controlled switch K1 and the second controlled switch K2 are relays or contactors to carry the large current that may continuously pass through under normal operating conditions and to have high reliability with mechanical isolation. The third controlled switch K3 and the fourth controlled switch K4 are fully controllable power semiconductor switching devices, such as metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated-gate bipolar transistors (IGBTs), to achieve fast on / off control and high-frequency path switching, meeting the dynamic response requirements of pre-charging and heating control.

[0042] The control module 30 precisely controls the on / off state of each controlled switch by sending drive signals to the control terminals of each controlled switch (such as the coil of a relay or the gate of a MOSFET). Using the switch state combinations shown in Table 1, the switch network 20 can construct current paths for three core operating modes:

[0043] Table 1: Switch Network 20 Operating Status Configuration Table. In another optional embodiment, to achieve precise closed-loop control of the pre-charge current, a current detection unit can be connected in series in the total output circuit of the battery pack. The current detection unit is connected to the control module 30 and is used to detect the current value flowing out of the positive output terminal of the battery pack and output the sampled current value to the control module 30. The control module 30 is also used to control the pre-charge current value output by the power conversion module 10 according to the sampled current value. This unit is set in the main circuit between the negative output terminal B- of the battery pack and the second controlled switch K2, or between the positive output terminal B+ of the battery pack and the first controlled switch K1. The current detection unit can be a high-precision, low-resistance sampling resistor (ShuntResistor), whose voltage across its terminals is proportional to the current flowing through it; it can also be a non-contact detection device such as a Hall effect current sensor. The output terminal of the current detection unit (i.e., the voltage or digital signal reflecting the current magnitude) is connected to the analog-to-digital converter (ADC) interface or a dedicated digital interface of the control module 30. During the pre-charging phase, the control module 30 collects the actual current value flowing through the detection unit in real time and compares it with the preset, safe target value of the pre-charging current. By adjusting the PWM duty cycle of the power conversion module 10, the actual pre-charging current is dynamically stabilized near the target value, thereby ensuring that the pre-charging process is both fast and safe. This achieves precise limitation and dynamic tracking of the pre-charging current, completely avoiding the instantaneous current surge that may occur in traditional resistor pre-charging schemes, and greatly improving the safety of the pre-charging process.

[0044] In an optional embodiment, the frequency of the alternating current is set to a preset value that matches the characteristic frequency of the internal resistance of the battery pack at low temperatures.

[0045] During the battery heating phase, optimizing the AC parameters injected into the battery is crucial for achieving efficient, rapid, and safe internal self-heating. Among these, the selection of the AC frequency is a core design parameter. The optimization principle of this invention lies in the fact that the internal impedance of a power battery (such as a lithium-ion battery), typically the sum of ohmic internal resistance and electrochemical polarization impedance, is not constant. Its value varies significantly with the frequency of the AC excitation signal, especially at low temperatures, where this frequency dependence is more pronounced. The battery's impedance-frequency characteristic curve (or impedance spectrum) usually exhibits local maxima at one or several specific frequency points; these frequency points can be called the characteristic frequencies of the battery's internal resistance under that operating condition.

[0046] Therefore, if an AC excitation is applied to the battery near the characteristic frequency of the internal resistance, according to Joule's law (P=I²*Z, where P is the heating power, I is the effective value of the current, and Z is the battery impedance), the maximum heat can be generated inside the battery under the same current amplitude limit, thereby achieving optimal heating efficiency.

[0047] After entering the battery heating stage, the control module 30 is configured to control the power conversion module 10 to output AC power at a specific frequency. This frequency is set based on the internal resistance characteristics of the battery pack at low temperatures, and its determination method includes, but is not limited to, the following two: Preset fixed frequency value: During system development, electrochemical impedance spectroscopy (EIS) tests are performed on the specific battery pack model under typical low-temperature environments (e.g., -20°C, -10°C, 0°C) to obtain its impedance-frequency curve, and one or more characteristic frequencies are analyzed and determined. Based on the test results, a frequency with relatively high heating efficiency over a wide temperature range and minimal impact on the battery's state of health (SOH) is selected as the preset value, for example, a fixed frequency within the range of 1kHz to 2kHz. This preset value is permanently stored in the non-volatile memory (e.g., Flash) of the control module 30. During heating, the control module 30 directly calls this preset frequency value to control the power conversion module 10 to output AC power at the corresponding frequency.

[0048] Dynamic Frequency Adjustment (Preferred Embodiment): To adapt to changes in battery status (such as aging, different low temperatures), the control module 30 can be configured with more advanced algorithms. The control module 30 can pre-store a frequency mapping table or calculation model indexed by parameters such as battery temperature and state of health (SOH). During heating startup, the control module 30 dynamically determines the optimal heating frequency target value based on the real-time collected battery temperature, by querying the mapping table or calculating through the model, and controls the power conversion module 10 to track it. For example, 1.5kHz is selected at -20°C, and 1.2kHz is selected at -10°C.

[0049] By setting the heating frequency to match the characteristic frequency of the battery's low-temperature internal resistance, this invention can ensure that the heating power is maximized within the safe current limit, shorten the time for the battery to recover from a low-temperature state to an operating temperature, improve the availability and energy efficiency of the system in cold environments, and avoid low heating efficiency or potential electrochemical side effects caused by improper frequency selection.

[0050] This invention also proposes an integrated functional circuit control method for a battery management system, applied to the integrated functional circuit of the battery management system; as shown in Figure 3, the integrated functional circuit control method for the battery management system includes: in response to a system startup command, acquiring battery pack state parameters and the bus voltage of the external load; determining the working stage based on the battery pack state parameters and the bus voltage; if in the pre-charging stage, controlling the switch network 20 to connect the power conversion module 10 between the battery pack and the positive input terminal of the external load, and controlling the power conversion module 10 to output a pre-charging current to pre-charge the bus capacitor in the external load; if in the battery heating stage, controlling the switch network 20 to connect the power conversion module 10 between the positive and negative output terminals of the battery pack, and controlling the power conversion module 10 to convert the DC output voltage of the battery into AC power and inject it into the battery pack; if in the normal operating stage, controlling the switch network 20 to connect the battery pack and the external load.

[0051] In step S101: In response to the system startup command, obtain the battery pack status parameters and the bus voltage of the external load.

[0052] When the system receives a start command such as power-on, wake-up, or charging connection, the control module 30 begins to work. First, it collects key initial state parameters through its analog front end (AFE) or sensor interface. These parameters include at least: battery pack state parameters, such as the total voltage of the battery pack V_bat, the minimum cell temperature T_bat, the state of health (SOH) of the battery pack, or the internal resistance calibration value.

[0053] Bus voltage of external load: obtained, for example, through a voltage sensing circuit connected between the positive input terminal L+ of the load and the reference ground.

[0054] Step S102: Determine the operating stage based on the battery pack status parameters and bus voltage.

[0055] The control module 30 has built-in decision logic (such as a state machine) to determine which working stage the system should enter based on the acquired parameters. An example of its decision logic is as follows: Determining whether to enter the pre-charging stage: Calculate the difference between the battery pack voltage and the bus voltage, ΔV = V_bat - V_bus. If ΔV is greater than a preset pre-charging start-up voltage threshold (e.g., 100V), it indicates that the bus capacitor voltage is very low, posing a risk of a large inrush current if the main circuit is directly closed. Therefore, it is determined that the pre-charging stage must be entered.

[0056] Determining whether to enter the battery heating stage: If ΔV is less than or equal to the pre-charge start-up voltage threshold (indicating that pre-charging is not required or pre-charging has been completed), the battery temperature is further checked. If the lowest cell temperature T_bat is lower than the preset heating start-up temperature threshold (e.g., 0°C or -10°C), it is determined that the battery heating stage needs to be entered to ensure that the battery can be safely and efficiently charged or discharged at low temperatures.

[0057] Determine whether to enter the normal operation stage: If ΔV is less than or equal to the pre-charge start-up voltage threshold and T_bat is higher than or equal to the heating start-up temperature threshold, then it is determined that the normal operation stage can be directly entered.

[0058] Step S103: If in the pre-charging stage, the control switch network 20 connects the power conversion module 10 between the battery pack and the positive input terminal of the external load, and controls the power conversion module 10 to output a pre-charging current to pre-charge the bus capacitor in the external load.

[0059] In one example, control module 30 can perform the following specific control actions: output a drive signal to configure switch network 20 as a pre-charge path. That is, control the first controlled switch K1 to open, the second controlled switch K2 to close, the third controlled switch K3 to close, and the fourth controlled switch K4 to open. Control the power conversion module 10 (such as a bidirectional Buck-Boost converter) to operate in Buck mode with current closed-loop control. Issue a pre-charge current command to power conversion module 10 and perform closed-loop regulation based on feedback from the current detection unit (as described in claim 5) to charge the bus capacitor with a controlled current. In addition, monitor the bus voltage V_bus in real time. When ΔV drops below a smaller pre-charge completion voltage threshold (e.g., 20V), pre-charge is determined to be complete. Subsequently, control module 30 first closes the first controlled switch K1 and then turns off the third controlled switch K3, and the system smoothly transitions to the main loop shoot-through state.

[0060] Step S104: If the battery is in the heating stage, the control switch network 20 connects the power conversion module 10 between the positive and negative output terminals of the battery pack, and controls the power conversion module 10 to convert the DC output voltage of the battery into AC power and inject it into the battery pack.

[0061] In one example, control module 30 can perform the following specific control actions: output a drive signal to configure the switching network 20 as an internal heating circuit. That is, control the first controlled switch K1 to open, the second controlled switch K2 to open, the third controlled switch K3 to open, and the fourth controlled switch K4 to close. Control the power conversion module 10 to operate in AC output mode. For example, for an H-bridge or bidirectional Buck-Boost converter, control its switching transistors to generate an alternating current of a specific frequency and amplitude. Inject AC power into the battery pack according to the set heating parameters (using a frequency that matches the characteristic frequency of the battery's low-temperature internal resistance). Simultaneously, continuously monitor the battery temperature. When the battery temperature rises above a preset heating stop temperature threshold (e.g., 10°C or 15°C), heating is determined to be complete. Control module 30 turns off the fourth controlled switch K4 and can determine whether to enter the normal operation stage or the pre-charging stage (if a load is connected after heating) based on subsequent needs (such as charging).

[0062] Step S105: If in normal operation, control switch network 20 connects the battery pack to the external load.

[0063] The control module 30 executes the simplest path configuration: it controls the first controlled switch K1 to close, the second controlled switch K2 to close, the third controlled switch K3 to open, and the fourth controlled switch K4 to open. At this time, the power conversion module 10 is bypassed, a low-loss direct connection is formed between the battery pack and the external load, and the system performs normal energy transfer.

[0064] In another embodiment, the logic for determining the operating stage (S102) can consider more complex conditions. For example, when determining whether to enter the heating stage, in addition to temperature conditions, the current state of charge (SOC) of the battery pack can also be considered. If the SOC is too low (e.g., below 5%), heating can be temporarily suspended or a more conservative heating power can be used to avoid excessive energy consumption during the heating process. Furthermore, the control method also includes a fault handling sub-process. At any stage, if the control module 30 detects faults such as overcurrent, switch sticking, or abnormal voltage, it will immediately interrupt the current operating mode, shut down all controlled switches, enter a safe fault state, and record the fault code.

[0065] In one embodiment, as shown in FIG4, the control power conversion module 10 outputs a pre-charge current to pre-charge the bus capacitor in the external load, including: step S301, monitoring the bus voltage of the external load.

[0066] After entering the pre-charge mode and starting the power conversion module 10 to output the pre-charge current, the control module 30 begins continuous monitoring of key state quantities. Among these, the bus voltage V_bus of the external load is the core parameter reflecting the pre-charge process. The control module 30 continuously acquires the voltage signal, V_bus, between the positive input terminal L+ of the load and the reference ground at a high sampling rate (e.g., 1 kHz) through its analog-to-digital converter (ADC) channel.

[0067] Step S302: Dynamically adjust the pre-charge current based on the real-time difference between the bus voltage and the battery pack voltage.

[0068] The control module 30 simultaneously or periodically acquires the total voltage V_bat of the battery pack. It calculates the real-time voltage difference ΔV = V_bat - V_bus. This difference ΔV directly reflects the remaining charging voltage space across the bus capacitor.

[0069] The control module 30 dynamically sets and adjusts the target value I_ref of the pre-charge current based on the magnitude of ΔV. A typical embodiment of its control strategy is as follows: Initial small current stage: When ΔV is large (e.g., >150V), it indicates that the capacitor voltage is extremely low. To avoid any possible instantaneous surges, the control module 30 sets a small initial target current I_ref_init (e.g., 10%-20% of the rated maximum pre-charge current).

[0070] During the ramp-up or step-up phase: As pre-charging progresses, V_bus increases, and ΔV decreases. Based on the value of ΔV, the control module 30 gradually increases I_ref according to a preset "current-voltage difference relationship curve" or by looking up a table. For example, for every 20V decrease in ΔV, I_ref increases by a certain amount. This design ensures that the charging current increases smoothly with the increase in capacitor voltage, rather than being constant current charging, further reducing stress.

[0071] Closed-loop regulation execution: The control module 30 uses the dynamically set I_ref as the target value for current closed-loop control (by adjusting the PWM duty cycle of the power conversion module 10 (Buck mode), the actual current I_sense fed back by the current detection unit accurately follows the changing target current I_ref).

[0072] This "voltage difference feedback" dynamic current adjustment method has significant advantages over the fixed current pre-charge scheme: it uses a small current when there is an initial high voltage difference, which greatly reduces the initial stress on the switching devices and capacitors; as the capacitor voltage increases, the current can be increased to shorten the total pre-charge time, thereby achieving the optimal balance between safety and efficiency.

[0073] Step S303: When the real-time difference drops below the first preset threshold, it is determined that the pre-charging is complete.

[0074] The first preset threshold ΔV_th is a key safety judgment parameter, and its value is much smaller than the pre-charge start threshold. ΔV_th is usually set according to the system safety margin and the small inrush current allowed when the main switch (such as a relay) is closed. For example, it is set to 5%-10% of the rated voltage of the battery pack, corresponding to specific values ​​such as 20V to 40V.

[0075] While dynamically adjusting the current, the control module 30 continuously compares the real-time voltage difference ΔV with the first preset threshold ΔV_th. When ΔV ≤ ΔV_th is detected, it indicates that the bus capacitor voltage V_bus is very close to the battery voltage V_bat. At this time, if the main positive relay (K1) is closed, the closing inrush current will be within a completely safe range. Therefore, the control module 30 immediately determines that "pre-charging is complete".

[0076] Switching action after judgment completion: After the judgment is completed, the control module 30 performs an orderly mode switching operation to eliminate race condition risk: First, the control module 30 outputs a drive signal to close the first controlled switch K1 (main positive relay). Since V_bus≈V_bat at this time, closing K1 will not generate a large current surge.

[0077] After confirming that K1 has been reliably closed (which can be determined by auxiliary contacts or voltage detection), the control module 30 outputs a drive signal to turn off the third controlled switch K3 and stop the PWM output of the power conversion module 10. At this point, the pre-charge circuit is cut off, and the main power circuit is established. Finally, the system smoothly transitions to the normal operation stage or waits for the next instruction (such as starting charging).

[0078] In another embodiment, as shown in FIG5, the control power conversion module 10 converts the DC output voltage of the battery into AC power, including: step S201, acquiring the real-time temperature and battery parameters of the battery pack.

[0079] When the control module 30 determines that the battery heating stage has begun, it does not immediately start heating with fixed parameters. Instead, it first collects the latest battery status information as input for optimization decisions. This information includes: Real-time temperature: typically the lowest temperature of a single cell within the battery pack, a key variable determining the intensity and parameters of the heating requirement. Battery parameters: parameters that reflect the current characteristics or state of the battery. These can be obtained through: Direct measurement or estimation: such as the current state of charge (SOC), state of health (SOH), DC internal resistance (R_dc), or current open-circuit voltage (OCV) of the battery pack. Preset or calibrated parameters: such as the battery's chemical type, rated capacity, and electrochemical impedance spectroscopy (EIS) database index measured at the factory.

[0080] These parameters are obtained through the BMS's sensor network, estimation algorithms, or read from memory.

[0081] Step S202: Based on the real-time temperature and battery parameters, query the preset mapping relationship to determine at least one target parameter among the current optimal heating current amplitude, frequency and waveform.

[0082] The control module 30 internally stores a "preset mapping relationship" for optimizing heating parameters. This mapping relationship is essentially a set of rules or data that maps the battery state to the optimal heating strategy. It can take the form of a multidimensional lookup table (LUT) or a parameterized calculation model, which can be a simplified formula or function based on the battery electrochemical and thermal model.

[0083] The "target parameter" may include: current amplitude: maximizing heating power, but strictly limited by the battery's "lithium deposition current threshold" (which is strongly correlated with temperature and SOC). Therefore, one of the core logics of the mapping relationship or model is to determine the maximum safe current amplitude that will not cause lithium deposition under different (T, SOC) combinations.

[0084] Frequency: Prioritize the selection of a frequency that matches the characteristic frequency of the battery's internal resistance at the current low temperature to maximize AC impedance and thus obtain higher heating power at the same safe current.

[0085] Waveform: Can be selected based on system complexity and efficiency. Square waves are easily generated by full-bridge or half-bridge circuits and have high heating power density; sine waves have low harmonic content and may be more battery-friendly. Mapping relationships can be specified based on experience or testing.

[0086] Step S203: Based on the target parameters, control the power conversion module 10 so that the alternating current output by the power conversion module 10 matches the target parameters.

[0087] After obtaining a set of target parameters (current amplitude, frequency waveform), the control module 30 converts them into precise drive commands for the power conversion module 10: the PWM generator of the control module 30 is configured to operate at the target frequency and generates signals to drive the switching transistors (such as the four transistors of an H-bridge or the two transistors of a Buck-Boost converter) according to the timing requirements of the target waveform (such as a square wave). Additionally, the control module 30 can use the target current amplitude as the target amplitude value of the AC current (for a square wave, this usually refers to the peak value; for a sine wave, it refers to the amplitude or effective value). It uses the real-time current sampling value fed back by the current detection unit, multiplies it with the target waveform template to obtain the instantaneous target current value, and dynamically adjusts the PWM duty cycle through an AC current closed-loop control algorithm (such as a coordinate transformation-based controller or a hysteresis comparator) to ensure that the amplitude, frequency, and waveform of the alternating current actually output by the power conversion module 10 track the target parameters.

[0088] It should be explained that this embodiment, by considering the impact of temperature and SOC on the battery's electrochemical safety window in real time and dynamically limiting the current amplitude, fundamentally prevents lithium dendrite precipitation that may be induced by low-temperature high-current charging or heating, greatly enhancing the battery's safety in low-temperature environments. Furthermore, by dynamically matching the heating frequency to the battery's changing internal resistance characteristics and allowing adjustment of the current amplitude within a safe range, it ensures that the system always operates at or near its optimal energy efficiency point throughout the entire heating process, shortening heating time and reducing energy consumption.

[0089] The present invention also discloses a battery management system, including: a battery pack, a load interface, and an integrated functional circuit of the battery management system.

[0090] It should be noted that the battery management system is a complete system-level solution with integrated pre-charging and low-temperature heating functions.

[0091] The battery pack consists of one or more battery cells (such as lithium-ion cells) connected in series and / or parallel, used to store and provide DC power. The battery pack has a positive output terminal B+ and a negative output terminal B-.

[0092] The battery pack is usually equipped with voltage acquisition lines and temperature sensors (such as NTC thermistors) inside or outside to transmit information such as the voltage and temperature of the individual battery cells to the control module 30.

[0093] The load interface is the port through which the battery management system electrically connects to an external power source or charging device. It includes at least one positive input terminal L+ and one negative input terminal L-.

[0094] In practical applications, this interface can be connected to a variety of external loads, such as, but not limited to: motor controllers: used to drive traction motors in electric vehicles and electric ships.

[0095] DC charging station: Used for fast DC charging of battery packs.

[0096] High-voltage accessories such as vehicle-mounted DC / DC converters or air conditioning compressors.

[0097] The specific structure of the integrated functional circuit of the battery management system is as described in the above embodiments. Since the battery management system adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0098] In brief, the circuit is connected in series on the main power path between the battery pack and the load interface. The first port of its power conversion module 10 is connected to the positive output terminal B+ of the battery pack, and its switching network 20 is connected between the battery pack, the second port of the power conversion module 10, and the load interface.

[0099] The control module 30 (i.e., BMS main controller) of the circuit is connected to the sensors and load interface status detection points in the battery pack, as well as the internal switch network 20 and current detection unit, through wiring harness or communication bus, to form a complete monitoring and control network.

[0100] The present invention also proposes an electrical device including the battery management system.

[0101] Typical examples of electrical equipment include, but are not limited to: electric vehicles: battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs): their high-voltage battery systems are the electrical equipment protected by this claim. An integrated battery management system is responsible for managing the power battery pack, enabling safe pre-charging during vehicle startup, rapid battery heating in low winter temperatures to ensure range and charging performance, and normal energy distribution during driving.

[0102] Electric vehicles: electric buses, electric trucks, electric construction machinery (such as excavators and forklifts), electric ships, electric aircraft (eVTOL): These large or special vehicles have extremely high requirements for the reliability, environmental adaptability and energy management efficiency of the power system. The integrated solution provided by this invention can effectively meet their needs.

[0103] Energy storage systems: residential energy storage systems, commercial and industrial energy storage systems, grid-side energy storage power stations: these systems need to operate stably under different ambient temperatures and avoid shocks when connected to the grid or load. The battery management system of this invention can ensure the safe grid connection and off-grid switching of energy storage battery packs, as well as self-starting and performance maintenance in low-temperature environments.

[0104] Portable high-power devices: drones (UAVs), power tools, outdoor power supplies: these devices are sensitive to size, weight, and low-temperature performance. The integrated design of this invention significantly improves the device's start-up success rate and discharge capability in cold environments without increasing its size.

[0105] The specific structure of the battery management system is as described in the above embodiments. Since this electrical device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0106] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An integrated functional circuit for a battery management system, characterized in that, include: Power conversion module, switching network and control module; The power conversion module and the switching network are disposed between the battery pack and the external load. The power conversion module has a first port connected to the positive output terminal of the battery pack and a second port selectively connected to the negative output terminal of the battery pack or the positive input terminal of the external load through the switching network. The control module is connected to both the power conversion module and the switching network. The control module is configured to: during the pre-charging phase, control the switching network to connect the power conversion module between the battery pack and the positive input terminal of the external load, and control the power conversion module to output a pre-charging current to pre-charge the bus capacitor in the external load; during the battery heating phase, control the switching network to connect the power conversion module between the positive and negative output terminals of the battery pack, and control the power conversion module to convert the DC output voltage of the battery into AC power and inject it into the battery pack.

2. The integrated functional circuit of the battery management system as described in claim 1, characterized in that, The power conversion module is a bidirectional Buck-Boost converter or an H-bridge inverter circuit.

3. The integrated functional circuit of the battery management system as described in claim 1, characterized in that, The switch network includes: a first controlled switch connected in series between the positive output terminal of the battery pack and the positive input terminal of the external load; a second controlled switch connected in series between the negative terminal of the battery pack and the negative input terminal of the external load; a third controlled switch connected in series between the second port of the power conversion module and the positive input terminal of the external load; and a fourth controlled switch connected in series between the second port of the power conversion module and the negative terminal of the battery pack.

4. The integrated functional circuit of the battery management system as described in claim 1, characterized in that, The frequency of the alternating current is set to a preset value that matches the characteristic frequency of the internal resistance of the battery pack at low temperatures.

5. The integrated functional circuit of the battery management system as described in any one of claims 1 to 4, characterized in that, The integrated functional circuit of the battery management system further includes: a current detection unit; the current detection unit is connected to the control module and is used to detect the current value flowing out of the positive output terminal of the battery pack and output the sampled current value to the control module; the control module is also used to control the pre-charge current value output by the power conversion module according to the sampled current value.

6. A method for controlling integrated functional circuits in a battery management system, characterized in that, The method for controlling the integrated functional circuit of the battery management system as described in any one of claims 1 to 5 includes: in response to a system startup command, acquiring battery pack status parameters and the bus voltage of an external load; determining the operating stage based on the battery pack status parameters and the bus voltage; if in the pre-charging stage, controlling the switch network to connect the power conversion module between the battery pack and the positive input terminal of the external load, and controlling the power conversion module to output a pre-charging current to pre-charge the bus capacitor in the external load; if in the battery heating stage, controlling the switch network to connect the power conversion module between the positive and negative output terminals of the battery pack, and controlling the power conversion module to convert the DC output voltage of the battery into AC power and inject it into the battery pack; if in the normal operating stage, controlling the switch network to connect the battery pack and the external load.

7. The integrated functional circuit control method for a battery management system as described in claim 6, characterized in that, The control power conversion module outputs a pre-charge current to pre-charge the bus capacitor in the external load, including: monitoring the bus voltage of the external load; dynamically adjusting the pre-charge current according to the real-time difference between the bus voltage and the battery pack voltage; and determining that pre-charging is complete when the real-time difference drops below a first preset threshold.

8. The integrated functional circuit control method for a battery management system as described in claim 6, characterized in that, The control power conversion module converts the DC output voltage of the battery into AC power, including: acquiring the real-time temperature and battery parameters of the battery pack; based on the real-time temperature and battery parameters, querying a preset mapping relationship to determine at least one target parameter among the current optimal heating current amplitude, frequency, and waveform; and controlling the power conversion module according to the target parameter so that the alternating current output by the power conversion module matches the target parameter.

9. A battery management system, characterized in that, It includes a battery pack, a load interface, and an integrated functional circuit for a battery management system as described in any one of claims 1 to 5.

10. An electrical appliance, characterized in that, Includes the battery management system as described in claim 9.

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