Charging control method and charging control device for battery management system

Abstract

The invention provides a charging control method and a charging control device for a battery management system. The control method comprises the step of selecting to enter a corresponding charging mode based on the charging state of the BMS. The charging modes comprise a large-current charging mode, a floating charging mode, a charging stopping mode and a charging protecting mode. Within the initial set time when the BMS starts to work, the BMS works in the protection charging mode. And in the protection charging mode, charging the battery within a protection charging current threshold value. And after the initial set time is over, selecting to enter one of the protection charging mode, the large-current charging mode, the floating charging mode and the charging stopping mode based on the charging state of the BMS. According to the invention, the problem that the BMS is damaged due to large circulating current generated when a plurality of BMSs with different voltages or capacities are connected in parallel is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery management, and in particular relates to a charging control method and a charging control device for a battery management system. Background Art

[0002] With the continuous advancement of battery technology, more and more devices (such as electric vehicles and UPS) use batteries as energy storage modules. However, overcharging or over-discharging during battery use can shorten the battery's service life and, in severe cases, lead to serious safety incidents such as fire and explosion. Therefore, a battery management system (BMS) is often installed to intelligently manage and maintain each battery cell. The BMS is the hub for managing and monitoring power batteries, responsible for managing, maintaining, and monitoring each battery module. It shoulders the important task of preventing overcharging and over-discharging, extending battery life, and ensuring normal battery operation.

[0003] A BMS is a system that combines software and hardware, typically powered by batteries. Therefore, while managing and monitoring the batteries, the BMS also consumes battery energy. Existing BMS charging solutions lack appropriate charging designs for the various scenarios encountered during the BMS charging process, resulting in numerous application issues.

[0004] Therefore, a BMS charging solution with multiple protection functions is urgently needed to solve the above problems. Summary of the Invention

[0005] Therefore, the object of the present invention is to overcome the above-mentioned defects of the prior art and provide a charging control method and a charging control device for a battery management system.

[0006] According to a first aspect, the present invention provides a charging control method for a battery management system, wherein the control method selects to operate in a corresponding charging mode based on the charging status of the battery management system, and the charging mode includes a high-current charging mode, a floating charging mode and a stop charging mode, wherein the charging mode also includes a protection charging mode, in which the battery is charged within a protection charging current threshold; and the control method includes: within an initial set time when the battery management system starts to work, the battery management system operates in the protection charging mode; after the initial set time when the battery management system starts to work, the battery management system selects to enter one of the protection charging mode, the high-current charging mode, the floating charging mode and the stop charging mode based on the charging status of the battery management system.

[0007] Preferably, based on the charging status of the battery management system, one of the protection charging mode, the high current charging mode, the floating charging mode and the stop charging mode is selected, including determining whether it is necessary to enter the protection charging mode before selecting to enter the high current charging mode.

[0008] Preferably, the selection of entering one of the protection charging mode, the high-current charging mode, the floating charging mode and the stop charging mode is based on the charging status of the battery management system, including: judging whether the stop charging condition is met based on the charging status of the battery management system, and if so, entering the stop charging mode; if the stop charging condition is not met, further judging whether the floating charging condition is met; if the floating charging condition is met, entering the float charging mode; if neither the stop charging condition nor the floating charging condition is met, further judging whether the protection charging condition is met; if the protection charging condition is met, entering the protection charging mode; if none of the stop charging condition, the floating charging condition and the protection charging condition are met, entering the high-current charging mode.

[0009] Preferably, after selecting to enter one of the protection charging mode, the high current charging mode, the floating charging mode and the stop charging mode based on the charging status of the battery management system, it includes: in the current charging mode selected to enter, the battery management system returns to execute the step of determining whether the stop charging condition is met based on the charging status of the battery management system at a set time interval.

[0010] Preferably, the determination of whether the protective charging condition is met includes: when the charging current is less than a first charging current threshold, entering the protective charging mode; wherein the first charging current threshold is determined according to the protective charging current threshold.

[0011] Preferably, the determination of whether the protection charging condition is met also includes: when the charging current is greater than the high current charging current threshold, entering the protection charging mode; wherein the high current charging current threshold is the maximum charging current set in the high current charging mode.

[0012] Preferably, after entering the protection charging mode, if the protection charging condition is no longer met, the protection charging mode is exited and the process returns to the step of determining whether the charging stop condition is met based on the charging state of the battery management system.

[0013] Preferably, in the float charge mode, when the charging current is greater than the float charge current threshold by a first set difference, it is determined that a fault has occurred in the charging circuit and the charging circuit is controlled to be disconnected; and / or in the protection charge mode, when the charging current is greater than the protection charge current threshold by a second set difference, it is determined that a fault has occurred in the charging circuit and the charging circuit is controlled to be disconnected.

[0014] Preferably, the charging stop condition includes at least one of the following conditions: the battery cell voltage is too high, the battery is fully charged, the battery cell average voltage is too high, the battery cell temperature is too high, and the battery cell temperature is too low.

[0015] Preferably, the judgment of whether the floating charge condition is met includes that when the maximum voltage of the single cell is greater than the first single cell voltage threshold, the floating charge condition is met; and when the float charge condition is met, if the corresponding release condition is established, then exit the float charge mode and return to the step of judging whether the stop charging condition is met based on the charging status of the battery management system; wherein, the release condition corresponding to the float charge condition includes: the maximum voltage of the single cell is less than the second single cell voltage threshold; wherein, the first single cell voltage threshold is greater than the second single cell voltage threshold.

[0016] According to a second aspect, the present invention provides a charging control device for a battery management system, comprising: a controllable fuse, a battery and a high-current charging switch arranged between the positive and negative poles of the battery management system, a protection charging module connected in parallel at both ends of the high-current charging switch, and a floating charging module connected in parallel at both ends of the high-current charging switch; wherein the controllable fuse is used to stop charging of the battery management system when a charging fault occurs; the high-current charging switch is a semiconductor switching device, used to control the maximum charging current within a set high-current threshold range; the protection charging module is used to control the maximum charging current within a set protection charging current threshold; the floating charging module is used to control the maximum charging current within a set floating charging current threshold; the controllable fuse, the high-current charging switch, the protection charging module and the floating charging module are controlled to be turned on or off by the battery management system, and among the high-current charging switch, the protection charging module and the floating charging module, only one can be turned on at the same time.

[0017] Compared to existing technologies, the charging control method of the present invention enables the BMS to enter a corresponding charging mode based on the charging status during charging. By defaulting to a protection charging mode when the BMS begins operation, it addresses the issue of damage to the BMS caused by large circulating currents generated when multiple BMSs with different voltages or capacities are connected in parallel. The present invention also addresses the issue of BMS overcharging caused by a short circuit in the sampling circuit or charging circuit. High-current charging current limits can be easily modified without hardware changes, making the charging control scheme more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0019] Figure 1 is a structural diagram of a charging control device for a battery management system according to an embodiment of the present invention;

[0020] Figure 2 This is a BMS charging timing diagram according to an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of mode switching logic according to an embodiment of the present invention;

[0022] Figure 4 Graph showing the results of UL testing using existing BMS charging solutions; and

[0023] Figure 5 This figure shows the results of a UL test using the BMS charging solution according to an embodiment of the present invention. Explanation of the reference numerals: 1-controllable fuse; 2-battery; 3-float charge switch; 4-high current charge switch; 5-protection charge switch; 6-sampling resistor; 7-discharge switch. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] Existing BMS charging solutions usually include two modes: high-current charging mode and floating charging mode. After the BMS starts working, it first enters the high-current charging mode, and controls the battery to be charged within the set high-current charging current threshold. When the battery cell voltage is charged to a certain level (that is, when the floating charging condition is met), it enters the floating charging mode, and continues to charge the battery within a relatively small floating charging current threshold until the battery is fully charged. After research, the inventors found that the existing BMS charging solution does not have corresponding charging designs for the various situations encountered during the BMS charging process, and there are many problems in application. For example, the sampling circuit is short-circuited and the current cannot be collected, causing the BMS to overcharge; the charging circuit is short-circuited, causing the BMS to overcharge; when multiple BMSs with different voltages or capacities are connected in parallel, the voltage difference is too large, resulting in a large circulating current, causing damage to one or more BMSs; changing the maximum charging current requires changing the hardware circuit (that is, the working logic needs to be redesigned). In response to the above problems, the inventors proposed a charging control device and control method for BMS, and the content of the invention will be explained in conjunction with specific embodiments below.

[0026] Figure 1 : This is a structural diagram of a charging control device for a battery management system according to an embodiment of the present invention. According to one embodiment of the present invention, the charging control device includes: a controllable fuse 1 provided between the positive electrode P+ of the BMS and the negative electrode P- of the BMS, a battery 2, a high-current charging switch 4, and a protective charging circuit ( Figure 1 Only schematically shown) and its protection charging switch 5, and the floating charging circuit ( Figure 1 (shown only schematically) and its floating charge switch 3, wherein the protection charging circuit and its protection charging switch 5 constitute a protection charging module, and the floating charge circuit and its floating charge switch 3 constitute a floating charge module. Among them, the controllable fuse 1 is controlled by the microcontroller MCU inside the BMS to determine whether it is blown, and is used to stop the charging and discharging of the BMS when a charging fault occurs, so as to isolate the faulty battery management system from other devices. After the floating charge switch 3 is turned on, the floating charge circuit controls the maximum charging current to be limited within the set floating charge current threshold, and is controlled to be turned on or off by the MCU. The high-current charging switch 4 is a semiconductor switching device, composed of a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT), each of which includes an anti-parallel parasitic diode or a body diode. The high-current charging switch 4 is used to control charging within the set high-current threshold range, and the MCU is responsible for controlling the on or off. After the protection charging switch 5 is turned on, the protection charging circuit controls the maximum charging current to be limited within the set protection charging current threshold, and is controlled to be turned on or off by the MCU. At the same time, the MCU controls the high-current charging switch 4, the protection charging switch 5 and the floating charging switch 3 so that only one of them can be turned on.

[0027] In some embodiments, a controllable fuse 1 is arranged between the positive pole P+ of the BMS and the positive pole of the battery 2, a protection charging module containing a protection charging switch 5, a floating charging module containing a floating charging switch 3, and a high current charging switch 4 are arranged between the negative pole P- of the BMS and the negative pole of the battery 2.

[0028] In some embodiments, a controllable fuse 1 is arranged between the negative pole P- of the BMS and the negative pole of the battery 2, a protection charging module containing a protection charging switch 5, a floating charging module containing a floating charging switch 3, and a high-current charging switch 4 are arranged between the positive pole P+ of the BMS and the positive pole of the battery 2.

[0029] In some embodiments, a sampling resistor 6 is provided on the negative electrode side of the battery 2 to collect current. The collected sampled current is used as the charging current, which is used as one of the criteria for selecting the charging mode. Other current sampling elements such as Hall current sensors can also be used instead of the sampling resistor.

[0030] Figure 1 Also shown is a discharge switch 7, located on the negative electrode side of battery 2, for controlling the conduction between battery 2 and the negative electrode P- of the BMS. Discharge switch 7 is a semiconductor switching device, while discharge switch 3 is composed of a MOSFET or IGBT. It should be noted that discharge switch 7 is not involved in the implementation of the present invention, so it will not be described in detail here.

[0031] When multiple BMSs with different voltages or capacities are connected in parallel, due to the different initial voltages or capacities, and taking into account various factors such as differences in the BMS's internal resistance, when the BMSs first start operating, the higher-voltage BMS will attempt to discharge to the lower-voltage BMS to balance the voltage difference. This results in circulating current. The magnitude of the circulating current depends on factors such as the voltage difference, internal resistance difference, and the BMS's capacity and charge / discharge status. Large circulating currents can damage BMS cells, as excessive current can cause battery overheating, damage internal battery structures, and even lead to safety accidents. To address this issue, according to one embodiment of the present invention, a charging control method for a BMS is proposed. In addition to high-current charging and floating charging modes, a protection charging mode is also provided, along with the conditions for entering the protection charging mode. The protection charging conditions include assuming that the BMS operates in the protection charging mode for an initial set time at the start of BMS operation. After the initial set time, the BMS enters high-current charging, floating charging, or another charging mode based on the charging status. In protection charging mode, the BMS controls the protection charging circuit to charge the battery within a set protection charging current threshold. The protection charging current threshold is greater than the floating charge current threshold and less than the high current charging threshold. According to multiple experiments by the inventors, in one embodiment of the present invention, the protection charging current threshold is 1.5-2.5A, preferably 2A. The initial setting time is 1 minute to 30 minutes. In one embodiment of the present invention, the initial setting time is preferably 15 minutes. When multiple BMSs with different voltages or capacities are connected in parallel, the BMS enters the protection charging mode by default when it starts working, and charges the battery within the set protection charging current threshold. This can gradually reduce the circulating current, alleviate the voltage difference between the parallel BMSs, and ensure the safe and stable operation of the BMS system.

[0032] Based on the set protection charging mode, the BMS charging control method of the embodiment of the present invention includes four charging modes: protection charging mode, high current charging mode, floating charging mode and stop charging mode. Figure 2This is a timing diagram of the BMS charging mode according to an embodiment of the present invention. The first stage is protection charging mode, which is the default charging mode when the BMS begins charging. Under normal circumstances, this mode must be maintained for the initial set time. The second stage is high-current charging mode, in which the BMS charges the battery within the set high-current charging current threshold range until the maximum voltage of the single cell reaches the first single cell voltage threshold, at which point high-current charging mode is exited. The high-current charging current threshold ranges from 0.1C to the maximum safe charging current allowed by the battery. The preferred high-current threshold range is greater than or equal to 0.75 times the protection charging current threshold and less than 0.5C. C represents the rated capacity of the battery in ampere-hours. A 0.5C rate indicates charging at a current 0.5 times the rated capacity of the battery in ampere-hours. For example, for a 10Ah battery, 0.5C represents a charging current of 5A. The third stage is float charging mode, in which the BMS controls the maximum charging current to charge the battery within the set float current threshold. In one embodiment of the present invention, the float current threshold is 50mA. Charging terminates when the battery is fully charged. The condition for the battery to be fully charged is that the average cell voltage of the BMS in the charging mode is greater than the first average voltage threshold, and the voltage difference between the maximum voltage of the single cell and the minimum voltage of the single cell is less than the voltage difference threshold.

[0033] Since the current charging status, including the cell voltage, charge level, and temperature, is unclear at the beginning of charging, after entering the protection charging mode by default, it is necessary to determine the next charging mode that the BMS needs to enter in combination with the BMS's charging status. In one embodiment of the present invention, a charging control method for a BMS is provided that can control the BMS's charging process to switch between protection charging mode, high current charging mode, floating charging mode, and stop charging mode.

[0034] Figure 3 The following is a schematic diagram of the mode switching logic according to an embodiment of the present invention. Figure 1 and Figure 3 , explaining in detail the workflow and state transitions of BMS during the charging process.

[0035] After the BMS begins charging, it proceeds to step S301. In step S301, when the BMS initiates charging, it defaults to protection charging mode. This mode protects the battery during the initial charging phase, preventing damage from excessive current. In this mode, the BMS performs the following operations: turning off high-current charging switch 4, turning on protection charging switch 5, and turning off float charge switch 3. At this point, the BMS controls the protection charging circuit to charge the battery within the set protection charging current threshold (e.g., 2A).

[0036] In step S302, the BMS determines whether the current charging status meets the conditions for stopping charging. These conditions may include the battery voltage reaching the preset charge termination voltage or the battery temperature exceeding a safety threshold. If the conditions are met, the BMS proceeds to step S303 to stop charging. If not, the BMS proceeds to step S304 to further determine the charging status.

[0037] In step S303, in response to the determination that charging needs to be stopped, the BMS shuts down all charging circuits, including shutting down the high-current charging switch 4, the protection charging switch 5, and the floating charge switch 3, thereby stopping charging to prevent possible overcharging or other charging-related problems.

[0038] In step S304, the BMS determines whether the current charging status meets the float charge condition. Float charge condition means the battery is nearly fully charged but has not yet reached the set charge termination condition. If the float charge condition is met, the system proceeds to step S305, where float charge mode operations are performed. If not, the system proceeds to step S306, where it continues monitoring and determines whether to enter protection charge mode.

[0039] In step S305, the BMS responds to the determination that it needs to enter the float charge mode and enters the float charge mode, i.e., it keeps the high-current charge switch 4 off, turns off the protection charge switch 5, and turns on the float charge switch 3. At this time, the BMS controls the maximum charge current to charge the battery within the set float charge current threshold (e.g., 50mA).

[0040] In step S306, the BMS determines whether the current charging state meets the protection charging condition. If so, the process proceeds to step S307; if not, the process proceeds to step S308.

[0041] In step S307, the BMS responds to the determination that it needs to enter the protection charging mode and enters the protection charging mode. That is, it keeps the high-current charging switch 4 off, turns on the protection charging switch 5, and turns off the floating charge switch 3. At this time, the BMS controls the protection charging circuit to charge the battery within the set protection charging current threshold (for example, 2A).

[0042] In step S308, if all other conditions are not met, the BMS enters high-current charging mode. High-current charging mode is a standard battery charging mode suitable for situations where the battery is low on charge and there are no other charging restrictions. In this mode, the BMS turns on high-current charging switch 4 to quickly charge the battery using a higher charging current. Simultaneously, the BMS turns off protection charging switch 5 and float charge switch 3.

[0043] In some embodiments, in at least one of the charging modes of steps S303, S305, S307, and S308, the BMS sequentially executes the judgment logic in step S302 and thereafter at set intervals and performs corresponding operations based on the judgment results. In one embodiment, the intervals can be 10ms, 100ms, 1s, 10s, or 1min. The BMS periodically determines the charging mode to enter and can adjust the charging mode in a timely manner based on the BMS's charging status.

[0044] In some embodiments, the charging stop condition in step S302 includes one of the following:

[0045] 10) Cell voltage is too high: The maximum cell voltage of the BMS cell exceeds the first cell voltage threshold; wherein the first cell voltage threshold is 3550mV to 3650mV. After multiple tests, the preferred first cell voltage threshold is 3600mV.

[0046] 20) The battery is fully charged: The average cell voltage of the BMS exceeds a first average voltage threshold, and the voltage difference between the maximum cell voltage and the minimum cell voltage is less than a voltage difference threshold. The first average voltage threshold is 3.4V to 3.5V. After multiple tests, the preferred first average voltage threshold is 3.45V, and the voltage difference threshold is 0.05V to 0.15V. The preferred voltage difference threshold is 0.1V.

[0047] 30) Excessive average cell voltage: The average cell voltage of the BMS exceeds the second average voltage threshold, which is between 3.55V and 3.65V. After multiple tests, the second average voltage threshold is preferably 3.6V.

[0048] 40) Cell temperature is too high: The maximum cell temperature of the BMS exceeds the first cell temperature threshold, which is between 58°C and 60°C. After multiple tests, the preferred first cell temperature threshold is 59°C.

[0049] 50) Cell temperature is too low: The lowest cell temperature of the BMS is lower than the third cell temperature threshold; wherein the third cell temperature threshold is -1°C to 1°C. After multiple tests, it is preferred that the third cell temperature threshold is 0°C.

[0050] In some embodiments, after any one or more of the above five conditions are met, that is, after the BMS enters the stop charging mode, when the release conditions corresponding to any one or more of the above conditions are met, the stop charging mode is exited and the process returns to step S302 to continue determining whether the stop charging conditions are met. The release conditions corresponding to the above five stop charging conditions include:

[0051] 11) The maximum cell voltage of the BMS battery cell is less than a second cell voltage threshold; wherein the second cell voltage threshold is 3500mV to 3400mV. After multiple tests, preferably, the second cell voltage threshold is 3450mV; wherein the first cell voltage threshold is greater than the second cell voltage threshold.

[0052] 21) After discharge or when the battery's remaining capacity (State of Charge, SOC) is lower than a remaining capacity threshold, wherein the remaining capacity threshold is 93% to 97%. After multiple tests, the preferred remaining capacity threshold is 95%.

[0053] 31) The average cell voltage of the BMS is less than a third average voltage threshold; wherein the third average voltage threshold is 3.4V to 3.5V. Preferably, the third average voltage threshold is 3.45V; wherein the second average voltage threshold is greater than the third average voltage threshold.

[0054] 41) The maximum temperature of the BMS battery cell is lower than a second battery cell temperature threshold, wherein the second battery cell temperature threshold is 55°C to 57°C. After multiple tests, it is preferred that the second battery cell temperature threshold is 57°C, wherein the first battery cell temperature threshold is greater than the second battery cell temperature threshold.

[0055] 51) The lowest temperature of the BMS battery cell exceeds a fourth battery cell temperature threshold; wherein the fourth battery cell temperature threshold is 3°C to 7°C. After multiple tests, preferably, the fourth battery cell temperature threshold is 5°C. wherein the third battery cell temperature threshold is less than the fourth battery cell temperature threshold.

[0056] In some embodiments, the float charge condition in step S304 includes: the maximum cell voltage is greater than or equal to a first cell voltage threshold. In some embodiments, if the BMS is in float charge mode, when the maximum cell voltage is less than a second cell voltage threshold, the BMS exits the float charge mode in step S305. This means that the float charge condition in step S304 is met and then removed, and the BMS returns to step S302 to determine whether the stop charging condition is met. The first cell voltage threshold is 3.47V to 3.53V, preferably 3.5V; the second cell voltage threshold is 3.4V to 3.45V, preferably 3.43V. The first cell voltage threshold is greater than the second cell voltage threshold. In one embodiment, after detecting that the float charge condition has been removed, the BMS may not immediately exit the float charge mode and return to step S302. Instead, after detecting that the float charge condition has been removed and a set time interval has elapsed, the BMS may return to step S302 for periodic determination to determine the next required charging mode before exiting the current float charge mode.

[0057] In the charging control circuit of a BMS, a sampling circuit is used to sample and measure signals such as current and voltage. The BMS charging strategy is formulated and adjusted based on the data provided by the sampling circuit, such as the charging current and charging time. If the sampling circuit shorts, there is no or only a very small voltage difference across the sampling resistor, causing the sampled current to display as zero or near zero. In this case, the sampled current does not represent the actual charging current and does not reflect the BMS's actual charging status, thus causing the charging strategy to fail and potentially causing the BMS to overcharge. To address this issue, according to one embodiment of the present invention, in step S306, the BMS determines whether protective charging conditions are met. Therefore, before entering high-current charging mode, if a sampling circuit short circuit is detected, the BMS will select protective charging mode to prevent overcharging. Alternatively, in at least one of the charging modes of steps S303, S305, S307, and S308, the BMS can promptly detect a sampling circuit short circuit by sequentially executing the judgment logic and corresponding operations of step S302 and subsequent steps at set intervals, and select protective charging mode to prevent overcharging.

[0058] In step S306, the protection charging condition is that the charging current is less than the first charging current threshold. The first charging current threshold is related to the protection charging current threshold, which can be 10% to 90% of the protection charging current threshold. In one embodiment of the present invention, the first charging current threshold is preferably set to 75% of the protection charging current threshold. For example, if the protection charging current threshold is 2A, the first charging current threshold is 1.5A. When the floating charge condition is not met, by setting the charging current to be less than the first charging current threshold as a condition for entering the protection charging mode, the problem of BMS charging strategy failure caused by the sampling circuit short circuit and the inability to collect the actual charging current can be avoided.

[0059] According to one embodiment of the present invention, in step S306, determining whether the protective charging condition is met may further include: when the charging current is greater than a high-current charging current threshold, the BMS enters a protective charging mode. This not only overcomes the problem of charging circuit short circuits in high-current charging mode, but also allows for convenient modification of the high-current charging current threshold in subsequent projects without hardware changes, making the charging solution more flexible. For example, the BMS can be modified to enter protective charging mode when the charging current is greater than 1.0C.

[0060] In some embodiments, the condition for exiting the protection charging mode (i.e., the condition for releasing the protection charging condition) is that the corresponding protection charging condition no longer holds. For example, if the protection charging condition is that the BMS charging current is less than the first charging current threshold, or the BMS charging current is greater than the high-current charging current threshold, or the protection charging mode is entered by default within the initial set time when the BMS starts operating; then the corresponding release condition for the protection charging condition is that the BMS charging current is greater than or equal to the first charging current threshold and less than the high-current charging current threshold, and the BMS has been operating in the protection charging mode for longer than the set time. After exiting the protection charging mode, the process returns to step S302 to determine whether the stop charging condition is met. In one embodiment, after detecting that the release condition for the protection charging condition is met, the protection charging mode may not be exited immediately and returned to step S302. Instead, after detecting that the release condition for the protection charging condition is met and the set time interval has expired, the BMS returns to step S302 for periodic determination to obtain the next charging mode to be entered, and then exits the current protection charging mode.

[0061] During the BMS charging process, in float and protection charging modes, if a short circuit occurs in the charging circuit, the charging current will increase abnormally, easily causing the battery cell voltage to rise rapidly, resulting in overcharging of the BMS and damage to the battery cells. To address this issue, according to one embodiment of the present invention, if the BMS is in float charging mode in step S305, based on a set first set difference, when the charging current exceeds the float current threshold by the first set difference, the BMS determines that a charging circuit fault has occurred, and at this time, the BMS controls controllable fuse 1 to open the circuit. If the difference between the charging current and the float current threshold is less than or equal to the first set difference, the charging current is determined to be within a safe range, and the BMS can continue to operate until the battery is fully charged. The BMS then opens controllable fuse 1, thereby cutting off the current flow. The value of the first set difference is related to the accuracy of the sampling circuit's sampling of the charging current in float charging mode. In one embodiment of the present invention, the first set difference is preferably 0.95A. For example, in float charging mode, the charging current should be maintained at approximately the float current threshold of 50mA. If the charging current is greater than 1A at this time, it can be determined that a charging circuit fault has occurred. This solves the problem of a short circuit in the charging circuit during float charging mode. According to another embodiment of the present invention, based on a set second set difference, if the BMS is in the protection charging mode of step S307, and the charging current exceeds the protection charging current threshold by the second set difference, it determines that a charging circuit fault has occurred. The BMS then controls controllable fuse 1 to open the circuit. If the difference between the charging current and the protection charging current threshold is less than or equal to the second set difference, the charging current is determined to be within a safe range. The BMS can continue to operate until the battery is fully charged, at which point it opens controllable fuse 1, thereby shutting off the current. The value of the second set difference depends on the accuracy of the sampling circuit's sampling of the charging current during the protection charging mode. In one embodiment of the present invention, the second set difference is preferably 0.8A. For example, in the protection charging mode, the charging current should not exceed the protection charging current threshold of 2A. If the charging current exceeds 2.8A, a charging circuit fault is determined. This solves the problem of a short circuit in the charging circuit during protection charging mode.

[0062] The results of UL testing using the existing BMS charging solution are as follows: Figure 4 As shown in the overcharge experiment of UL test, the rated capacity of BMS is 6Ah and the rated charging current is 3A. First, discharge the BMS to the cell voltage of about 3V, then short-circuit the charging circuit and charge the BMS with 1.1 times the rated current of 3A, that is, 3.3A. Figure 4As can be seen in the figure, when the BMS stops charging, the cell voltage reaches nearly 4.5V, exceeding the safe voltage range of 2.0V-4.0V for the cell, resulting in authentication failure. In the existing BMS charging solution, the maximum voltage of the BMS single cell reaches 3.5V before entering float charge mode. In float charge mode, the charging current is detected to be 3.3A, exceeding the 1A limit. The MCU then sends a drive signal to blow the controllable fuse. Because the detection time plus the time it takes to blow the controllable fuse takes approximately 20 seconds, the cell voltage has exceeded the cell platform voltage. At this point, the 3.3A charging current causes the cell voltage to rise rapidly, causing the test to fail.

[0063] The results of the UL test of the BMS charging control solution according to the present invention are as follows Figure 5 As shown, the BMS is discharged to a cell voltage of approximately 3V, then the charging circuit is short-circuited and charged with 1.1 times the rated current. Charging begins at the 26th second. While in protection charging mode, the BMS detects a charging current greater than 2.8A. At the 31st second, the MCU determines a charging circuit fault. The MCU sends a drive signal to blow the controllable fuse, which blows at the 47th second, halting charging. At the time of charging cessation, both the maximum and minimum cell voltages are within the safe voltage range of 2.0V-4.0V, ensuring certification.

[0064] In another embodiment of the present invention, a computer-readable storage medium is provided, on which a computer program or executable instructions are stored. When the computer program or executable instructions are executed, the control of BMS charging as described in the above embodiment is implemented. The implementation principle is similar and will not be repeated here. In an embodiment of the present invention, a computer-readable storage medium can be any tangible medium that can store data and can be read by a computing device. Examples of computer-readable storage media include hard disk drives, network attached storage (NAS), read-only memory, random access memory, CD-ROM, CD-R, CD-RW, magnetic tape, and other optical or non-optical data storage devices. Computer-readable storage media may also include computer-readable media distributed on a network-coupled computer system so that computer programs or instructions can be stored and executed in a distributed manner.

[0065] In another embodiment of the present invention, an electronic device is provided, comprising a processor and a memory, wherein the memory is used to store executable instructions that can be executed by the processor, wherein the processor is configured to execute the executable instructions stored on the memory, and when the executable instructions are executed, the charging control method for the BMS described in the aforementioned embodiment is implemented. The implementation principle is similar and will not be repeated here.

[0066] References in this specification to "various embodiments," "some embodiments," "one embodiment," or "an embodiment" refer to a particular feature, structure, or property described in connection with the embodiment being included in at least one embodiment. Thus, the appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or properties may be combined in any suitable manner in one or more embodiments. Thus, particular features, structures, or properties shown or described in connection with one embodiment may be combined, in whole or in part, with features, structures, or properties of one or more other embodiments without restriction, as long as the combination is not illogical or inoperable.

[0067] In this specification, the expressions "including," "having," and similar terms are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices. "A" or "an" does not exclude a plurality of cases. In addition, the elements in the drawings of this application are for illustrative purposes only and are not drawn to scale.

[0068] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein but includes various changes and modifications that may be made without departing from the scope of the present invention.

Claims

1. A charging control method for a battery management system, wherein the control method selects to operate in a corresponding charging mode based on the charging state of the battery management system, the charging mode including a high current charging mode, a floating charging mode, and a stop charging mode, wherein: The charging mode also includes a protection charging mode, in which the battery is charged within a protection charging current threshold; as well as The control method includes: During the initial set time when the battery management system starts to work, the battery management system operates in the protection charging mode; After an initial set time when the battery management system starts to work, one of the protection charging mode, the high-current charging mode, the floating charging mode and the stop charging mode is selected based on the charging state of the battery management system.

2. The charging control method according to claim 1, wherein: Based on the charging status of the battery management system, one of the protection charging mode, the high current charging mode, the floating charging mode and the stop charging mode is selected, including determining whether it is necessary to enter the protection charging mode before selecting to enter the high current charging mode.

3. The charging control method according to claim 1, wherein: Selecting to enter one of the protection charging mode, the high current charging mode, the floating charging mode, and the stop charging mode based on the charging state of the battery management system includes: Based on the charging state of the battery management system, determining whether a stop charging condition is met, and if so, entering the stop charging mode; if not, further determining whether a float charging condition is met; If the float charge condition is met, the float charge mode is entered; if neither the stop charge condition nor the float charge condition is met, whether the protection charge condition is met is further determined; If the protection charging condition is met, the protection charging mode is entered; if the stop charging condition, the floating charging condition, and the protection charging condition are not met, the high current charging mode is entered.

4. The charging control method according to claim 3, wherein: After selecting to enter one of the protection charging mode, the high-current charging mode, the floating charging mode, and the stop charging mode based on the charging state of the battery management system, the method includes: In the current charging mode selected for entry, the battery management system executes the step of determining whether a charging stop condition is met based on the charging state of the battery management system at a set time interval.

5. The charging control method according to claim 3, wherein: The determining whether the protection charging condition is met includes: when the charging current is less than a first charging current threshold, entering the protection charging mode; The first charging current threshold is determined according to the protection charging current threshold.

6. The charging control method according to claim 3, wherein: The determining whether the protection charging condition is met further includes: when the charging current is greater than a high current charging current threshold, entering the protection charging mode; The high-current charging current threshold is the maximum charging current value set in the high-current charging mode.

7. The charging control method according to any one of claims 3 to 6, wherein: After entering the protection charging mode, if the protection charging condition is no longer met, the protection charging mode is exited and the process returns to the step of determining whether the charging stop condition is met based on the charging state of the battery management system.

8. The charging control method according to claim 3, wherein: In the float charge mode, when the charging current is greater than the float charge current threshold by a first set difference, it is determined that a fault has occurred in the charging circuit, and the charging circuit is controlled to be disconnected; and / or In the protection charging mode, when the charging current is greater than the protection charging current threshold by a second set difference, it is determined that a fault has occurred in the charging circuit, and the charging circuit is controlled to be disconnected.

9. The charging control method according to claim 3, wherein: The charging stop condition includes at least one of the following conditions: the battery cell voltage is too high, the battery is fully charged, the battery cell average voltage is too high, the battery cell temperature is too high, and the battery cell temperature is too low.

10. The charging control method according to claim 3, wherein: The determining whether the floating charge condition is met includes: when the maximum voltage of the single cell is greater than a first single cell voltage threshold, the floating charge condition is met; as well as When the float charge condition is met and the corresponding release condition is met, the float charge mode is exited and the process returns to the step of determining whether the stop charging condition is met based on the charging state of the battery management system; wherein the release condition corresponding to the float charge condition includes: the maximum voltage of the single cell is less than the second single cell voltage threshold; Wherein, the first battery cell voltage threshold is greater than the second battery cell voltage threshold.

11. A charging control device for a battery management system, comprising: A controllable fuse, a battery and a high-current charging switch are arranged between the positive and negative electrodes of the battery management system, a protection charging module is connected in parallel at both ends of the high-current charging switch, and a floating charging module is connected in parallel at both ends of the high-current charging switch; wherein, The controllable fuse is used to stop charging of the battery management system when a charging failure occurs; The high-current charging switch is a semiconductor switch device, which is used to control the maximum charging current to be within a set high-current threshold range; The protection charging module is used to control the maximum charging current to be within a set protection charging current threshold; The floating charge module is used to control the maximum charging current to be within a set floating charge current threshold; The controllable fuse, the high-current charging switch, the protection charging module and the floating charging module are controlled to be turned on or off by the battery management system, and only one of the high-current charging switch, the protection charging module and the floating charging module can be turned on at the same time.

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