CN111999663A

CN111999663A - Battery connecting wire breakage detection device

Info

Publication number: CN111999663A
Application number: CN202010774227.7A
Authority: CN
Inventors: 张兰芳; 张亚; 姚丹丹
Original assignee: Hefei Boas Battery Technology Co Ltd
Current assignee: Hefei Boas Battery Technology Co Ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-11-27

Abstract

The invention discloses a device for detecting the disconnection of a battery connecting wire, which is connected in parallel with the two ends of a single battery and at least comprises a power supply unit, a charging unit, a discharging unit, a sampling unit, a control unit, a storage unit and a communication unit, wherein the power supply unit is used for providing energy for the device; the charging unit is used for performing charging operation on the single batteries; the discharge unit is used for performing discharge operation on the single batteries; the storage unit is used for storing at least the following parameter information in advance, and the control unit is used for controlling the device to perform charging operation, discharging operation or non-operation on the single batteries, controlling the sampling unit to sample a plurality of voltage sampling values of the single batteries in different working states, calculating the relation between the plurality of voltage sampling values and the preset parameter information, and judging whether the corresponding single batteries have line break faults or not according to the relation. The technical scheme of the invention can be suitable for various battery environments and states, and can easily position which sampling line is broken.

Description

Battery connecting wire breakage detection device

Technical Field

The invention relates to the technical field of battery management systems of electric automobiles and energy storage power stations, in particular to a device for detecting disconnection of a battery connecting wire.

Background

Because the single voltage and capacity of the storage devices such as storage batteries and super capacitors and the power generation devices such as photovoltaic systems (for convenience of explanation, batteries and battery packs are used for replacement in the following) are low, the single voltage and capacity are difficult to be directly used in large systems, and in practical application, a plurality of batteries are often required to be connected in series to improve the voltage, and a plurality of batteries are often connected in parallel to improve the capacity.

Because the production environment, the process parameters, the raw materials and the like are difficult to be completely consistent, each produced single battery has differences. And the difference between the unit cells may be enlarged as time goes by due to the difference in use environment. Due to the factors of chemical characteristics, each single battery has a safe operation range, including parameters such as voltage, current, temperature and power, and the operation range of each parameter has a great influence on the service life of the battery. Of these electrical parameters, the cell voltage is particularly important and must be limited to a reasonable range. After the single batteries are connected in series, the whole battery pack is charged and discharged together, the current or ampere hours passing through each battery are the same, and due to the difference between the single batteries, the situation that a single battery is fully charged firstly and the single battery is discharged firstly inevitably occurs. In addition, in order to ensure safety and battery life, the entire battery pack must be stopped from being charged as long as one battery is fully charged, and the entire battery pack must be stopped from being discharged as long as one battery is discharged, so the BMS must monitor each cell in real time. In an actual system, numerous factors such as structural design, harness quality, worker installation, mechanical shock/impact, etc., may cause the sampling harness between the BMS and the battery to be disconnected, causing the BMS to sample the battery voltage inaccurately.

As shown in fig. 1, due to the disconnection of the Bat4 sampling line, the input pin corresponding to the sampling line at the analog front end is suspended, the voltage is not constant, and the B4 and B5 battery voltages sampled by the BMS are incorrect and cannot reflect the real state of the battery, so that the battery system cannot operate normally and safely. Industries such as electric vehicles, energy storage power stations and communication base stations have high requirements on reliability, products are required to have a self-checking function, and errors can be automatically reported when faults occur.

In order to solve the problem of self-checking of the disconnection of the sampling line of the battery-related device, it is a conventional practice to add an RC filter circuit to the input terminal of the sampling line of the BMS, and to add two controllable current sources I1 and I2, as shown in fig. 2. When the disconnection detection is carried out, the two current sources are closed, the voltage of each battery is measured and recorded, then the two current sources are opened, and the voltage of each battery is measured and recorded again. If there is a wire break, as in the case of the B3+ sampling line in FIG. 2, C is turned on after the current source is turned on_F3Discharged by the current source, so that the sampling voltage of the battery B3 is smaller; c_F4Is charged by the current source so that the sampled voltage of battery B4 is larger. And comparing the voltage values sampled at the previous and subsequent times, and if the voltage values exceed a preset threshold value delta V, determining that the sampling line is broken.

However, the above prior art solutions have at least the following technical drawbacks:

firstly, when a power battery pack is charged and discharged at a large current, the battery has large voltage change, and particularly in the application occasion of an electric vehicle, when the battery is rapidly switched back and forth between different states of large-current discharge and brake energy feedback (charging), the delta V threshold value is difficult to select, and the compromise between the detection rate and the misjudgment is difficult.

Secondly, when the voltage of the single battery is relatively low, the current source discharge is difficult to ensure that the two previous sampling voltages have a large enough difference, and the phenomenon of missing judgment occurs.

Thirdly, before the detection algorithm is operated, the filter capacitor corresponding to the broken line number is discharged completely, and the current source has no charge to discharge, such as C in FIG. 2_F3When the MCU is electrified, the MCU is not electrified, the voltage difference does not exist in the two voltage sampling processes, and the disconnection state cannot be detected.

In addition, when an active equalization circuit exists in the system, the active equalization circuit has a large-capacity filter capacitor, and the current capacity is far larger than the current of a current source for line break detection, while the voltage difference between the two previous sampling and the next sampling in the existing detection method is closely related to the parameters such as the filter capacitor value, the sampling interval time and the like, and when the active equalization circuit exists in the system, the line break detection algorithm can be seriously interfered.

Due to the above disadvantages, the existing detection scheme has a large risk of missing detection and false detection. Therefore, it is necessary to provide a technical solution to solve the technical problems of the prior art.

Disclosure of Invention

In view of the above, it is necessary to provide a device for detecting disconnection of a battery connection line, which makes the sampling values of the single batteries in the two states of normal connection and disconnection of the sampling lines have a large difference by using the device for detecting disconnection of the battery connection line under different output working states, and at the same time, sets the parameter V reasonably_{Opening device}、V_Opener、V_{Height of}And V_{Is low in}The value selection range can not only accurately judge the disconnection fault, but also easily position which sampling line is disconnected.

In order to solve the technical problems in the prior art, the technical scheme of the invention is as follows:

the device at least comprises a power supply unit, a charging unit, a discharging unit, a sampling unit, a control unit, a storage unit and a communication unit, wherein the power supply unit is used for providing energy for the device;

the charging unit is used for performing charging operation on the single batteries;

the discharge unit is used for performing discharge operation on the single battery;

the storage unit is used for storing at least the following parameter information in advance, wherein V₀₊Represents the upper limit of the normal range of the cell, V_0-Represents the lower limit of the normal range of the single battery; v_{Opening device}Indicating an output constant voltage value of the charging unit which is significantly greater than V₀₊；V_OpenerIndicating the input voltage range of the power supply unitLower limit value, which is significantly less than V_0-(ii) a Setting a first comparison threshold V_{Height of}The value of the voltage drop is obviously larger than the loop impedance voltage drop and V₀₊Sum of significantly less than V_{Opening device}Setting a second comparison threshold V_{Is low in}To a value significantly less than V_0-The difference with the loop impedance voltage drop is obviously greater than V_Opener；

The control unit is connected with the charging unit, the discharging unit, the sampling unit, the storage unit and the communication unit and is used for controlling the device to perform charging operation, discharging operation or non-work on the single battery, controlling the sampling unit to sample a plurality of voltage sampling values of the single battery under different working states, calculating the relation between the plurality of voltage sampling values and preset parameter information and judging whether the corresponding single battery has a broken line fault or not according to the relation;

and the communication unit is used for sending the judgment result to the application circuit.

In a further improvement, the plurality of voltage sampling values sampled by the sampling unit in different working states of the device at least comprise a first voltage sampling value V₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutFirst voltage sample value V₀The voltage sampling value is used for sampling the single battery when the device does not work; second voltage sampling value V_{Charging device}Sampling voltage sampling values sampled when the device performs charging operation on the single batteries; third voltage sampling value V_PutThe voltage sampling value sampled when the device performs a discharging operation on the unit battery is obtained.

As a further improvement, when the first voltage sampling value is within the normal range of the battery, namely V_0-＜V₀＜V₀₊When, if V_{Charging device}＞V_{Height of}Or V_Put＜V_{Is low in}Judging that the corresponding single battery has a disconnection fault;

when V is₀＞V₀₊When, if V_Put＜V_{Is low in}Judging that the corresponding single battery has a disconnection fault;

when V is₀＜V_0-When, if V_{Charging device}＞V_{Height of}And judging that the corresponding single battery has a disconnection fault.

As a further improvement, if V_{Charging device}＞V_{Height of}And V is_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

As a further improvement scheme, the battery pack is formed by connecting a plurality of single batteries in series, and each single battery is connected with one device in parallel.

As a further improvement, the device is further provided with a multi-way selection switch, and the multi-way selection switch is connected with the plurality of single batteries and is used for switching on each single battery one by one according to the control instruction of the control module.

As a further improvement, assuming that the battery pack is formed by connecting N single batteries in series, N +1 connecting lines are shared between the application circuit and the battery pack, and when the control module determines that the ith single battery and the (i + 1) th single battery have a disconnection fault, wherein i is greater than 0 and less than N, the BAT-i connecting line is determined to be disconnected;

otherwise, if the control module only judges that the 1 st single battery has a disconnection fault, the connection line is judged to be the disconnection of the BAT-0 connection line; or if the control module only judges that the Nth single battery has the disconnection fault, the BAT-N connection line is judged to be disconnected.

As a further improvement, the power supply unit is a single battery, a battery pack or an auxiliary power supply.

As a further improvement scheme, the control unit is realized by adopting an MCU.

As a further development, the device is integrated in an application circuit.

As a further improvement, the output of the charging unit has a constant current and constant voltage characteristic.

As a further improvement, the battery pack is any one of a storage battery, a fuel cell, a super capacitor or a photovoltaic panel.

Compared with the prior art, the invention has the following technical effects:

1. the device of the invention utilizes its outputUnder different working conditions, the sampling values of the single batteries in the two states of normal connection and disconnection of the sampling line have great difference, and simultaneously, the parameter V is reasonably set_{Opening device}、V_Opener、V_{Height of}And V_{Is low in}The value selection range can not only accurately judge the broken line, but also easily position which sampling line is broken.

2. The technical scheme of the invention has strong applicability, has no requirement on the application environment of the battery, and is applicable even in the environment with instantaneous large current charge and discharge, such as a hybrid vehicle; meanwhile, the range of the voltage of the battery is not required, and accurate judgment can be made no matter whether the battery is overcharged, overdischarged or in a normal range; in addition, the historical states of the battery and the BMS are not required, and the battery and the BMS can be detected at any time.

3. The device can be used independently, can also be integrated in an application circuit, and can be applied to different application occasions.

Drawings

Fig. 1 is a schematic diagram of a BMS sampling line disconnection.

Fig. 2 is a schematic diagram of a method for detecting a connection state of a sampling line in the prior art.

Fig. 3 is a schematic diagram of a device for detecting disconnection of a battery connection line.

FIG. 4 is a schematic diagram of an equivalent circuit of voltage sampling in a charging state of the device of the present invention.

FIG. 5 is a diagram illustrating a timing sequence for detecting a disconnection of a sampling line according to a preferred embodiment of the present invention.

Fig. 6 is a schematic diagram of voltage changes of the single battery under different working states of the active balancing unit.

FIG. 7 is a schematic diagram of an equivalent circuit of voltage sampling in the discharge state of the device of the present invention.

Fig. 8 is a schematic diagram of an equivalent circuit of a broken sampling line.

Fig. 9 is a schematic view of a device for detecting disconnection between a battery pack and a battery connection line.

Fig. 10 is a flow chart of the method for detecting disconnection of the battery connection line according to the present invention.

The following specific embodiments will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

The technical solution provided by the present invention will be further explained with reference to the accompanying drawings.

Referring to fig. 3, a schematic block diagram of the device for detecting disconnection of a battery connection line according to the present invention is shown, which illustrates an application scenario of a single battery, wherein an application circuit is connected to positive and negative ends of the battery through a connection line, the device is connected in parallel to two ends of a single battery, and at least includes a power supply unit, a charging unit, a discharging unit, a sampling unit, a control unit, a storage unit and a communication unit, wherein the power supply unit is configured to provide energy for the device; the charging unit is used for performing charging operation on the single battery, the output of the charging unit has constant current and constant voltage characteristics, and the output voltage constant voltage is far higher than the normal voltage range of the battery and smaller than the safe input voltage range of the power supply unit; the discharge unit is used for performing a discharge operation on the unit cells, and is mainly used for consuming redundant energy of the unit cells.

A storage unit for storing at least parameter information in advance, wherein V₀₊Represents the upper limit of the normal range of the cell, V_0-Represents the lower limit of the normal range of the single battery; v_{Opening device}Indicating an output constant voltage value of the charging unit which is significantly greater than V₀₊；V_OpenerRepresents the lower limit value of the input voltage range of the power supply unit, which is obviously smaller than V_0-(ii) a Setting a first comparison threshold V_{Height of}The value of the voltage drop is obviously larger than the loop impedance voltage drop and V₀₊Sum of significantly less than V_{Opening device}Setting a second comparison threshold V_{Is low in}To a value significantly less than V_0-The difference with the loop impedance voltage drop is obviously greater than V_Opener；

The control unit is connected with the charging unit, the discharging unit, the sampling unit, the storage unit and the communication unit and controls the normal work of each functional unit of the device. The control unit can control the device to perform charging operation, discharging operation or non-operation on the single batteries, wherein the charging operation is performed by the charging unit, the discharging operation is performed by the discharging unit, and the non-operation state does not perform the charging operation or the discharging operation. Meanwhile, the control module controls the sampling unit to sample a plurality of voltage sampling values of the single battery under different working states, then calculates the relation between the plurality of voltage sampling values and preset parameter information, judges whether the corresponding single battery has a disconnection fault or not according to the relation, and sends a disconnection fault judgment result to the application circuit by the communication unit.

Referring to fig. 4, which is a schematic diagram of an equivalent circuit of voltage sampling of the device of the present invention in a charging state, B1 represents a single battery; r1 and R2 are equivalent line impedances between the application circuit or device and the battery, including all impedances included in the charging and discharging loop, such as wire impedance, connector contact impedance, fuse impedance, PCB wiring impedance, battery internal resistance, and artificially added integrated resistance, and since the equivalent impedance includes line distribution impedance, the impedance exists certainly, and is only different in size for different application systems; the sampling unit is used for sampling the battery voltage; v_SRepresenting the voltage collected by the sampling unit.

The plurality of voltage sampling values sampled by the sampling unit under different working states of the device at least comprise a first voltage sampling value V₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutFirst voltage sample value V₀The voltage sampling value is used for sampling the single battery when the device does not work; second voltage sampling value V_{Charging device}Sampling voltage sampling values sampled when the device performs charging operation on the single batteries; third voltage sampling value V_PutThe voltage sampling value sampled when the device performs a discharging operation on the unit battery is obtained.

The control unit obtains a first voltage sampling value V₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutAnd calculating to obtain the relation between the single batteries and preset parameter information, and judging whether the corresponding single batteries have line break faults or not.

The technical scheme is that the sampling values have great difference in two states of normal connection and disconnection of the sampling line by utilizing different working states of the single battery, and simultaneously, the parameter V is reasonably set_{Opening device}、V_Opener、V_{Height of}And V_{Is low in}Selecting a range of values fromAnd whether the single battery has the disconnection fault can be accurately judged.

The principle of the implementation of the technical solution is described in detail below, and taking the sampling line disconnection detection timing shown in fig. 5 as an example, it should be noted that the sampling line disconnection detection timing (Vs voltage sampling during static state, charging, and discharging) can be arbitrarily adjusted as long as the charging, discharging, and voltage comparison logic during non-operation are ensured.

Referring to fig. 5, the device is firstly controlled not to work, and the sampled battery voltage is recorded as a first voltage sampling value V₀(ii) a Then controlling the device to charge the battery, and recording the sampled battery voltage as a second voltage sampling value V_{Charging device}(ii) a Finally, the device is controlled to discharge the battery, and the sampled battery voltage is recorded as a third voltage sampling value V_Put。

Because the battery is an energy storage device, the change of the battery voltage needs time, the capacity of the power battery is large, the working equalizing current of the active equalizing module is small relative to the battery capacity, the voltage sampling period is short, and the change of the equalizing current to the battery voltage is small and can be ignored within the range of a plurality of sampling periods.

When the sampling line is connected normally, due to the clamping effect of the battery on the voltage, as shown in fig. 4, the voltage V sampled by the sampling unit_SIs the algebraic sum of the battery voltage and the voltage drop over the equivalent line impedance, which is the product of the impedance value and the current through the loop. For example, when the battery B1 is charged, the charging current flows out from the charging unit, flows back to the active equalization unit after passing through the R1, the B1 and the R2, the voltage drop caused on the equivalent line impedances R1 and R2 is the same as the positive direction of the voltage of the battery B1, namely the voltage V sampled by the sampling unit_{Charging device}Battery B1 voltage V₀+ line impedance drop > V₀. Referring to fig. 6, voltage changes of the unit cell under different operating conditions are shown, wherein a solid line represents the change of the sampling voltage when the sampling line is normally connected, and V is shown during the charging period_{Charging device}Is significantly greater than V₀And is less than V_{Height of}。

Referring to FIG. 7, the device of the present invention is shown in the discharged stateWhen the battery B1 is discharged, current flows out of the discharge unit, flows back to the active equalization circuit after passing through R2, B1 and R1, voltage drops caused on equivalent line impedances R1 and R2 are opposite to the positive direction of the voltage of the battery B1, namely the voltage V sampled by the sampling unit_PutBattery B2 voltage V₀Line impedance drop<V₀As can be seen from the discharge period in fig. 6, V_PutIs significantly less than V₀And is greater than V_{Is low in}。

When the sampling line is disconnected, as shown in FIG. 8, the voltage V_SThe clamping effect of the battery is lost and no loop current exists in the circuit. When charging battery B1, voltage V is due to no load_SRises rapidly, reaches and maintains the output constant voltage value V designed by the charging unit_{Opening device}In fig. 6, the dotted line represents the change of the sampling voltage when the sampling line is disconnected, and the voltage V sampled by the sampling unit in the charged state_S＝V_{Opening device}(ii) a When discharging battery B1, voltage V is not present as input power from battery B1_SRapidly decreases until reaching the lower limit V of the input voltage range of the power supply unit_OpenerThen, the discharge unit stops working, the voltage does not continuously decrease, and the voltage V sampled by the sampling unit is in a discharge state_S＝V_Opener。

It is clear from fig. 6 that there is a significant difference in the variation trend of the sampling voltage between the normal connection and disconnection state of the sampling line, and when the sampling line is normally connected, V is_{Charging device}Is significantly lower than V_{Height of}，V_PutIs obviously higher than V_{Is low in}(ii) a When the sampling line is disconnected, V_{Charging device}＝V_{Opening device}Is obviously higher than V_{Height of}，V_Put＝V_OpenerIs significantly lower than V_{Is low in}. Therefore, whether the connecting line is disconnected or not can be easily judged only by reasonably designing and comparing the threshold parameters. For this purpose, two comparison thresholds V are provided_{Height of}And V_{Is low in}Requires V_{Height of}Is obviously larger than the sum of the line impedance voltage drop and the upper limit value of the battery voltage range and is obviously smaller than the output constant voltage value V of the active equalization_{Opening device}(ii) a Requirement V_{Is low in}Significantly less than the lower limit of the battery voltage range and the line impedance dropIs poor and is obviously larger than the lower limit value V of the input voltage range of the active equalization circuit_OpenerNamely: v_{Opening device}＞V_{Height of}＞(V₀₊+ line impedance drop), (V_0-Line impedance drop) > V_{Is low in}＞V_OpenerIn which V is₀₊Upper limit of normal battery range, V_0-The lower limit of the normal battery range.

Based on the principle, the invention provides sampling line disconnection detection judgment logic, which specifically comprises the following steps:

when the first voltage sampling value V₀In the normal range of the battery, i.e. V_0-＜V₀＜V₀₊When it is determined by one of the charging state and the discharging state, if V_{Charging device}＞V_{Height of}Or V_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

Otherwise, when V₀＞V₀₊At this time, if the battery has an overcharge condition, the battery voltage itself is high (abnormal condition, such as abnormal charger, abnormal BMS, etc.), and V may also occur when the connection line is normally connected in a charged state_{Charging device}＞V_{Height of}Therefore, in this case, an accurate determination cannot be made in the charged state, and it is necessary to exclude this case with the discharged state. That is, when V₀＞V₀₊When, if V_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

In the same way, when V₀＜V_0-At this time, if the battery has an over-discharge condition, V may occur when the battery voltage may be close to the starting voltage of the discharge cell_Put＜V_{Is low in}Therefore, in this case, accurate determination cannot be made in the discharge state, and it is necessary to exclude this case by charge equalization. That is, when V₀＜V_0-When, if V_{Charging device}＞V_{Height of}And judging that the corresponding single battery has a disconnection fault.

In addition, regardless of the first voltage sampling value V₀In what range, if V_{Charging device}＞V_{Height of}And V is_Put＜V_{Is low in}And the corresponding single battery can be directly judged to have the disconnection fault.

According to the judgment logic, the technical scheme of the invention has no requirement on the range of the voltage of the battery, and can make correct judgment in the normal range, the overcharge state, the overdischarge state and other states; the historical states of the battery and the BMS are not required, and the battery and the BMS can be detected at any time.

As shown in fig. 9, the application circuit of the device of the present invention is connected to each battery cell in the battery pack through a connection wire, and the most typical application is a battery management system BMS, taking the battery pack as an example, which is composed of 8 battery cells, the application circuit and the power battery pack share 9 connection wires, which are numbered BAT-0 to BAT-8.

By adopting the technical scheme, the invention not only can judge whether the disconnection fault occurs, but also can accurately position which connecting line has the disconnection fault. Assuming that the battery pack is formed by connecting N single batteries in series, N +1 connecting lines are shared between the application circuit and the battery pack, that is, the number of the single batteries in fig. 3 is expanded to N. When the ith single battery and the (i + 1) th single battery are judged to have the disconnection fault through the algorithm, if the connection line is disconnected, the BAT-i connection line is judged to be disconnected if i is more than 0 and less than N; because a disconnection fault occurs in one connecting wire, two adjacent single batteries can be influenced.

Otherwise, if only the 1 st single battery is judged to have the disconnection fault through the algorithm, the BAT-0 connection line is judged to be disconnected; or if the algorithm only judges that the Nth single battery has the disconnection fault, the BAT-N connection line is judged to be disconnected.

As can be seen from the above analysis, if only the sampled voltage of battery B1 is abnormal, BAT-0 is considered to be disconnected; if only the sampled voltage of the battery BN is abnormal, the BAT-N is considered to be disconnected;

if both B1 and B2 are abnormal, the BAT-1 is considered to be disconnected; and if both B2 and B3 are abnormal, the BAT-2 is considered to be disconnected, and the like.

In practical applications, a separate disconnection detecting device may be provided for each single battery, as shown in fig. 9. Or a plurality of single batteries can share one broken line detection device, and then the broken line detection device controls each single battery one by one through switch switching. For example, each 10 single batteries share one disconnection detection device, and the switch may be a multiplexer, but is not limited thereto.

In a preferred embodiment, the power supply unit is a single battery, a battery pack or other forms of energy storage units such as an auxiliary power supply.

The battery pack according to the present invention is any of power storage and generation devices such as a battery, a fuel cell, a super capacitor, a photovoltaic panel, and the like.

The technical scheme of the invention can be applied to a battery management system, a balance maintenance device, charging and discharging equipment, detection equipment and the like of storage devices such as a storage battery pack and a super capacitor pack and power generation devices such as a photovoltaic system and the like.

The device can be used independently, can also be integrated in an application circuit, and can be applied to different application occasions.

Referring to fig. 10, the present invention further provides a method for detecting a disconnection of a battery connection line, where a battery pack is formed by serially connecting a plurality of single batteries, and a device for detecting a disconnection of a battery connection line is connected in parallel to two ends of each single battery, which is also the above-mentioned technical solution, and is not described herein again.

The device control unit executes the following algorithm to detect whether each unit cell has a disconnection fault:

step S1: presetting parameter information in which V₀₊Represents the upper limit of the normal range of the cell, V_0-Represents the lower limit of the normal range of the single battery; v_{Opening device}Representing the output constant voltage value of the active equalization unit, which is significantly greater than V₀₊；V_OpenerRepresents the lower limit value of the input voltage range of the active equalization unit, and the value is obviously less than V_0-(ii) a Setting a first comparison threshold V_{Height of}The value of the voltage drop is obviously larger than the loop impedance voltage drop and V₀₊Sum of significantly less than V_{Opening device}Setting a second comparison threshold V_{Is low in}To a value significantly less than V_0-The difference with the loop impedance voltage drop is obviously greater than V_Opener；

Step S2: obtaining each under different working conditions of the deviceA plurality of voltage sampling values of the single batteries, wherein at least a first voltage sampling value V is included₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutFirst voltage sample value V₀The voltage sampling value of the single battery is sampled by the sampling unit when the device does not work; second voltage sampling value V_{Charging device}When the device performs charging operation on the single battery, the sampling unit samples the voltage of the single battery; third voltage sampling value V_PutWhen the device performs discharge operation on the single battery, the voltage sampling value of the single battery is sampled by the sampling unit;

step S3: the control unit calculates a first voltage sampling value V₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutAnd the relation between the parameter information and the preset parameter information, and whether the corresponding single battery has the disconnection fault or not is judged according to the relation.

The specific judgment logic is as follows:

when the first voltage sample is within the normal range of the battery, i.e. V_0-＜V₀＜V₀₊When, if V_{Charging device}＞V_{Height of}Or V_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

When V is₀＞V₀₊When, if V_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

If V_{Charging device}＞V_{Height of}And V is_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

The technical scheme is that the sampling values have great difference in two states of normal connection and disconnection of the sampling line by utilizing different working states of the single battery, and simultaneously, the parameter V is reasonably set_{Opening device}、V_Opener、V_{Height of}And V_{Is low in}And the value range is selected, so that whether the single battery has a disconnection fault or not can be accurately judged.

The invention can not only judge whether the disconnection fault occurs, but also accurately position which connecting line has the disconnection fault. Assuming that the power battery pack is formed by connecting N single batteries in series, N +1 connecting wires are shared between the BMS system and the power battery pack, and when the ith single battery and the (i + 1) th single battery are judged to have a wire break fault through an algorithm, if the number 0< i < N, the BAT-i connecting wire is judged to be broken;

otherwise, if the algorithm only judges that the 1 st single battery has a disconnection fault, the BAT-0 connection line is judged to be disconnected; or if the algorithm only judges that the Nth single battery has the disconnection fault, the BAT-N connection line is judged to be disconnected. The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The device for detecting the disconnection of the battery connecting line is characterized in that the device is connected with two ends of a single battery in parallel and at least comprises a power supply unit, a charging unit, a discharging unit, a sampling unit, a control unit, a storage unit and a communication unit, wherein,

the power supply unit is used for supplying energy to the device;

the storage unit is used for storing at least the following parameter information in advance, wherein V₀₊Represents the upper limit of the normal range of the cell, V_0-Represents the lower limit of the normal range of the single battery; v_{Opening device}Indicating an output constant voltage value of the charging unit which is significantly greater than V₀₊；V_OpenerRepresents the lower limit value of the input voltage range of the power supply unit, which is obviously smaller than V_0-(ii) a Setting a first comparison threshold V_{Height of}The value of the voltage drop is obviously larger than the loop impedance voltage drop and V₀₊Sum of significantly less than V_{Opening device}Setting a second comparison threshold V_{Is low in}To a value significantly less than V_0-The difference with the loop impedance voltage drop is obviously greater than V_Opener；

2. The device for detecting the disconnection of the battery connection line according to claim 1, wherein the plurality of voltage samples sampled by the sampling unit in different operating states of the device at least include a first voltage sample V₀A second voltage sampling value V_{Charging device}And a third voltage sample value V_PutFirst voltage sample value V₀The voltage sampling value is used for sampling the single battery when the device does not work; second voltage sampling value V_{Charging device}Sampling voltage sampling values sampled when the device performs charging operation on the single batteries; third voltage sampling value V_PutThe voltage sampling value sampled when the device performs a discharging operation on the unit battery is obtained.

3. According to the rightThe device for detecting disconnection of a battery connection line according to claim 2, wherein when the first voltage sample value is within a normal range of the battery, i.e., V_0-＜V₀＜V₀₊When, if V_{Charging device}＞V_{Height of}Or V_Put＜V_{Is low in}Judging that the corresponding single battery has a disconnection fault;

4. The device for detecting disconnection of battery connection line according to claim 2, wherein if V is_{Charging device}＞V_{Height of}And V is_Put＜V_{Is low in}And judging that the corresponding single battery has a disconnection fault.

5. The device for detecting the disconnection of the battery connecting wire according to any one of claims 2 to 4, wherein the battery pack is formed by connecting a plurality of single batteries in series, and each single battery is connected with one device in parallel.

6. The device for detecting the disconnection of the battery connecting wire according to any one of claims 5, wherein a multi-way selection switch is further arranged, and the multi-way selection switch is connected with the plurality of single batteries and is used for switching on each single battery one by one according to a control command of the control module.

7. The device for detecting the disconnection of the battery connecting wire according to claim 5, wherein if the battery pack is formed by connecting N single batteries in series, N +1 connecting wires are shared between the application circuit and the battery pack, and when the control module judges that the ith single battery and the (i + 1) th single battery have the disconnection fault, wherein 0< i < N, the BAT-i connecting wire is judged to be disconnected;

8. The device for detecting disconnection of battery connection line according to claim 1, wherein the power supply unit is a single battery, a battery pack or an auxiliary power supply.

9. The device for detecting the disconnection of the battery connecting wire according to any one of claims 1 to 4, wherein the control unit is implemented by using an MCU.

10. The device for detecting disconnection of battery connection cord according to any of claims 1-4, wherein the device is integrated in the application circuit.