CN212875395U

CN212875395U - Battery sampling line misconnection protection circuit in BMS system

Info

Publication number: CN212875395U
Application number: CN202021750496.1U
Authority: CN
Inventors: 吴建锋; 王金铭; 徐振宇; 王章权; 任条娟
Original assignee: Zhejiang Shuren University
Current assignee: Zhejiang Shuren University
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2021-04-02
Anticipated expiration: 2030-08-20

Abstract

The utility model discloses a battery sampling line misconnection protection circuit in BMS system, every monomer battery positive negative pole all is connected with the BMS system through the sampling line, its characterized in that, this circuit includes control module, enables the control unit, drive unit, MOS switch unit and relay unit at least, wherein, every monomer battery positive negative pole all connects a relay unit, all relay unit's response output end is connected with the first pin of control module jointly, when any sampling line connection is wrong, this response output end can both produce the sensing signal; and the control module controls the second pin to output a control signal after acquiring the induction signal. Adopt the technical scheme of the utility model, BMS can the short-term test sampling line misconnection condition to the MOS switch of all branches of control cut-off, thereby thoroughly break off the contact between BMS and the battery, ensure BMS system safety.

Description

Battery sampling line misconnection protection circuit in BMS system

Technical Field

The utility model relates to a BMS system especially relates to a battery sampling line misconnection protection circuit in BMS system.

Background

In a power battery system, a plurality of batteries are connected in series to realize large voltage output, and because the number of single batteries is large and the performance parameters of each single battery are different, the safety and the service life of the power battery are greatly influenced. Referring to fig. 1, a Battery Management System (BMS) is generally used in the prior art to synchronize charging and discharging of each battery cell, so as to ensure that the remaining capacity of each battery cell is substantially consistent, and a battery equalization technique is most commonly used at present. The positive and negative ends of each single battery are connected with the BMS system through sampling lines, and n +1 sampling lines are arranged on n single batteries. Because the sampling line is numerous, if the wrong condition of sampling line connection appears in BMS system assembling process, the BMS system will produce the negative voltage, can lead to balanced module unable normal work. Therefore, it is necessary to take a protective measure to prevent damage to the BMS system due to a sampling line connection error.

In order to solve the technical problem of the reverse connection between the positive terminal and the negative terminal of the battery, a conventional solution in the prior art serially connects a MOS switch circuit to the positive terminal or the negative terminal of the battery, as shown in fig. 2. When the single battery lines are normally connected, the switching circuit is designed to enable the grid voltage of the P-MOS tube to be lower than the voltage of a source electrode, and the switching tube is conducted; when the line connection of the single battery is reversed, the PMOS grid voltage is higher than the source voltage, and the switching tube is cut off, so that the protection effect is realized. However, this solution is only suitable for protecting the reverse connection of a single output power line, and in the BMS system, there are many battery sampling lines, and when the sampling lines between the single batteries are connected in reverse across a string, the solution of fig. 2 cannot protect the right or left. Referring to fig. 3, in an application scenario of 4 strings of single batteries, when sampling lines B1 and B4 are connected in a wrong manner, it can be known from the potential relationship of the poles of the MOS switching tubes of the branches that although the switching tubes of the branches B2 and B4 are turned off, the switching tubes of the branches B1 and B3 are still turned on, which may cause a negative voltage between sampling lines B3 and B1, and may easily cause circuit damage. In addition, the driving voltage of each branch MOS switch in fig. 3 is taken from a single battery, and the voltage of the single battery is low, so that the starting is difficult, and the effective application in the full SOC range cannot be guaranteed.

Therefore, for the application scenario of the BMS system, the sampling line misconnection protection circuit needs to be redesigned to meet the practical requirements.

SUMMERY OF THE UTILITY MODEL

In view of this, it is necessary to provide a mis-connection protection circuit for a battery sampling line in a BMS system, which can quickly detect the mis-connection condition of the sampling line and control MOS switches that cut off all branches, thereby completely disconnecting the connection between the BMS and the battery and ensuring the safety of the BMS system.

In order to solve the technical problem existing in the prior art, the technical scheme of the utility model as follows:

a misconnection protection circuit of battery sampling lines in a BMS system is disclosed, wherein the positive and negative electrodes of each single battery are connected with the BMS system through the sampling lines, the circuit at least comprises a control module, an enabling control unit, a driving unit, an MOS (metal oxide semiconductor) switch unit and a relay unit, wherein the positive and negative electrodes of each single battery are connected with one relay unit in parallel, the induction output ends of all the relay units are connected with a first pin of the control module together, and when any sampling line is misconnected, the induction output ends can generate induction signals; the control module controls the second pin to output a control signal after acquiring the induction signal;

the enabling control unit is connected with a second pin of the control module and the driving unit and is used for temporarily outputting an enabling signal in the future of the control signal to enable the driving unit to output a driving voltage and outputting a non-enabling signal to enable the driving unit to close the output when the control signal comes;

and each sampling line is connected with an MOS switch unit in series, the driving unit is connected with all the MOS switch units, when the driving unit outputs driving voltage, all the MOS switch units are switched on, otherwise, all the MOS switch units are switched off.

As a further improvement, the relay unit adopts a voltage relay, the input end of the relay is connected in parallel with two ends of the single battery, and a third resistor R3 and a first diode D1 are connected in series in an input loop of the relay unit; one end of the output end of the relay is connected with the first ground end, and the other end of the output end of the relay is used as an induction output end and connected with a first pin of the control module;

as a further improvement, the third resistor R3 is a PTC thermistor.

As a further improvement, the coil of the relay adopts PTC material.

As a further improvement, the enabling control unit comprises an optical coupler U1, a first resistor R1, a second resistor R2 and a first MOS transistor, the light emitter of the optical coupler U1 is controlled by a control signal, one end of the light receiver of the optical coupler U1 is connected to a second ground, the other end of the light receiver is connected to the gate of the first MOS transistor and one end of the first resistor R1, and the other end of the first resistor R1 is connected to a power supply VDD; the source electrode of the first MOS tube is connected with the second ground end, and the drain electrode of the first MOS tube is connected with the enable end of the driving unit.

As a further improvement, the MOS switch unit is realized by NMOS or PMOS.

As a further improvement, the control module is integrated in the BMS system.

As a further improvement, the optical coupler U1 is a PhotoMOS coupler.

As a further improvement, the driving unit employs a switching power supply.

As a further improvement, the control module is implemented by a unit machine, a first pin of the control module is configured to be triggered by external interruption, and when the sensing signal is generated, the control module immediately triggers an interruption program.

As a further improvement, the control module is implemented by a logic control circuit, and a first pin of the control module acquires an induction signal, so that a second pin of the control module generates a control signal.

Compared with the prior art, the utility model discloses following technological effect has:

1. the utility model adopts the voltage relay, which can directly utilize the pressure difference of the single battery to realize the control; meanwhile, the PTC thermistor is connected in series with the input loop of the relay, so that when the sampling line is misconnected across a plurality of strings of batteries, the relay can still be ensured to work within a safe voltage range, and the reliability of the circuit under extreme conditions is improved;

2. the utility model adopts the driving unit to output the driving voltage to control all the MOS switch units, the control module can realize the connection of synchronously controlling all the sampling line MOS switch units by only one pin to control the enabling end of the driving unit, and the hardware structure is greatly simplified; meanwhile, the control module is isolated from the driving unit through the optocoupler, and any state change of the battery end cannot affect the BMS system, so that the safety performance of the BMS system is greatly improved;

3. the MOS switch unit is independently controlled by the driving unit, the on-off state of the MOS switch unit is only determined by the driving voltage, and the MOS switch unit is irrelevant to the type of the battery and the SOC state, and can be quickly started and conveniently adjusted.

Drawings

Fig. 1 is a schematic diagram of a wrong connection of a sampling line of a battery pack.

Fig. 2 is a schematic diagram of the prior art.

Fig. 3 is a schematic diagram illustrating the principle of reverse connection of a plurality of batteries in the prior art.

Fig. 4 is the utility model discloses battery sampling line misconnection protection circuit's principle schematic diagram among the BMS system.

Fig. 5 is a schematic diagram of the relay unit according to the present invention.

Fig. 6 is a schematic block diagram of the circuit of the present invention when the multiple batteries are reversely connected.

The following detailed description of the invention will be made in conjunction with the above-described drawings.

Detailed Description

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

In the BMS system, every battery cell all is connected with the BMS system through independent sampling line, because the sampling line is more, the phenomenon that connects the mistake can appear in the pencil connection inevitability, especially when the sampling line strides the multi-string battery and connects the mistake, often can cause serious influence to the BMS system, however prior art scheme still can not effectively solve this type of technical problem.

In order to solve the above technical problem, referring to fig. 4, it is shown that the utility model provides a schematic diagram of a battery sampling line misconnection protection circuit in a BMS system, positive and negative poles of each single battery are all connected with the BMS system through sampling lines, a protection circuit is arranged therebetween, the circuit at least comprises a control module, an enabling control unit, a driving unit, an MOS switch unit and a relay unit, wherein, positive and negative poles of each single battery are all connected with a relay unit, the sensing output ends of all relay units are connected with the first pin of the control module together, and when any sampling line is misconnected, the sensing output end can generate a sensing signal; the control module controls the second pin to output a control signal after acquiring the induction signal; the control module is integrated in the BMS system, so that the control resources of the BMS system can be shared, and an additional control chip is not required. The control module can be realized by a unit machine or a logic control circuit, when the singlechip is adopted for realization, the first pin is configured to be triggered by external interruption, and when the induction signal is generated, the control module can trigger and output the control signal at once. When the control module is implemented by adopting a logic control circuit, a gate circuit can be adopted to implement corresponding control logic, and integrated chips such as a comparator and the like can also be adopted to design the control logic, so that a first pin of the control module can generate a control signal after acquiring an induction signal, and a second pin of the control module can generate a control signal.

Referring to fig. 5, the principle schematic diagram of the relay unit that is shown, the utility model discloses a relay produces inductive signal, and its principle is, and the input of relay connects in the battery cell both ends, concatenates first diode D1 at its input circuit, and first diode D1 joins conversely at the positive negative pole both ends of battery cell, and when the sampling line connection was normal, first diode D1 was by, and whole input circuit was by, did not produce extra consumption. When the sampling lines are reversely connected, the first diode D1 is conducted, the input loop is started to work, the coil at the input end of the relay generates a magnetic field, the switch at the output end of the relay is attracted, and then an induction signal is generated; in the circuit of fig. 5, one end of the output end of the relay is connected with the first ground end, and the other end of the output end of the relay is connected with the first pin of the control module as the sensing output end; when the sampling line is connected normally, the switch at the output end of the relay is cut off, and the fourth resistor R4 is pulled up to the VCC end of the power supply, so that the first pin of the control module is at a high level; when the sampling lines are reversely connected, the switch at the output end of the relay is closed, so that the first pin of the control module is at a low level, namely, an induction signal is generated. In a preferred embodiment, a first pin of the control module is configured to be triggered by external interrupt, when the sensing signal is generated, the first pin is changed from a high level to a low level to trigger an interrupt event, the control module immediately executes an interrupt program, and controls a second pin thereof to output a control signal, so that all MOS switches are turned off, and the connection of all sampling lines is cut off.

In the technical scheme, when all the battery sampling lines are normally connected, the cathode voltage of the diodes in all the input loops is higher than the anode voltage, all the relays are closed, and the MOS switches are all switched on. And any two sampling lines are reversely connected or more than two sampling lines are wrongly connected, at least one relay input loop is conducted to generate an induction signal.

In the technical scheme, the relay unit adopts the voltage relay, the relay is controlled by directly utilizing the voltage difference of the single battery, and meanwhile, the voltage relay has larger coil internal resistance, the working current of the input loop is small, and the relay can be effectively protected. In practice, the sampling lines may be connected reversely across a plurality of batteries, as shown in fig. 6, taking 4 battery strings as an example, when two sampling lines B1 and B3 are connected reversely, the input voltages of the relays J2 and J3 are connected reversely, the relay input circuit is turned on, and then the sensing signal is output, the control module executes corresponding control after acquiring the sensing signal, cuts off the connection of all the sampling lines, thoroughly isolates the connection between the batteries and the BMS, and effectively protects the BMS system.

However, because the sampling line connection error of the battery pack is random, in practice, the sampling line may cross n series of batteries and may be connected with two adjacent sampling lines in error, and the input voltage of the relay input loop is the voltage of a single battery; the sampling line can be connected across several batteries in a staggered manner, when the sampling line is connected across 2 or 3 strings of batteries in a staggered manner, a certain voltage relay bears 2-3 times of reverse voltage of the single battery, and the working current can be within a rated range due to the fact that the voltage relay has large coil internal resistance. In extreme cases, the total positive and the total negative are connected reversely, the input voltage of the relay is the voltage of the whole battery pack at the moment, the actual voltage far exceeds the rated voltage of the relay, and the relay can be damaged.

However, in order to be able to adapt to the uncertainty of a faulty sampling line in practice, the input voltage of the relay must guarantee: the relay can be started by one battery voltage, and the working voltage of the relay is still within the rated range when the n batteries are under the voltage. Therefore, the relay input circuit is also connected with a third resistor R3 in series, and a PTC thermistor is adopted, the resistance value of the thermistor is positively changed along with the working temperature of the circuit, namely, the resistance value of the PTC thermistor is smaller at normal temperature, the partial pressure is smaller, and the relay can be controlled by one battery voltage; when the input loop has larger reverse connection voltage, the current value is also large, the thermistor R3 is heated by the large current value, the resistance value is increased, and the voltages at the two ends of the thermistor are increased, so that the voltages at the two ends of the coil are reduced to be in a safe range, the relay is effectively protected, and the reliability of the circuit under extreme conditions is improved.

In a preferred embodiment, the coil of the relay is made of PTC materials, the internal resistance of the coil can change along with the positive change of the temperature of the coil, when the sampling line is connected across n series of batteries in a wrong mode, the loop current is increased, the temperature of the coil is increased, the internal resistance of the coil is further increased, and the loop current is reduced. The coil is made of PTC materials, so that the dynamic range of the input voltage of the relay can be effectively enlarged, and the relay can still be in a safe working range when higher voltage is input.

In fig. 4, the enable control unit controls the enable terminal of the driving unit and thus controls the output state of the driving unit. The enabling control unit is connected with a second pin of the control module and the driving unit and is used for temporarily outputting an enabling signal in the future of the control signal to enable the driving unit to output a driving voltage and outputting a non-enabling signal to enable the driving unit to close the output when the control signal comes; and each sampling line is connected with an MOS switch unit in series, the driving unit is connected with all the MOS switch units, when the driving unit outputs driving voltage, all the MOS switch units are switched on, otherwise, all the MOS switch units are switched off. In a preferred embodiment, the enabling control unit comprises an optical coupler U1, a first resistor R1, a second resistor R2 and a first MOS transistor, wherein a light emitter of the optical coupler U1 is controlled by a control signal, one end of a light receiver of the optical coupler U1 is connected with a second ground, the other end of the light receiver is connected with a grid electrode of the first MOS transistor and one end of a first resistor R1, and the other end of the first resistor R1 is connected with a power supply VDD; the source electrode of the first MOS tube is connected with the second ground end, and the drain electrode of the first MOS tube is connected with the enable end of the driving unit. When the sampling lines are normally connected, the second pin of the control module has no output, the optocoupler U1 is not conducted, the grid potential of the first MOS transistor is pulled up to the power supply VDD voltage by the first resistor R1, the first MOS transistor is conducted, and the driving unit enables and outputs driving voltage to start all MOS switch units; when any sampling line is connected in error and the second pin outputs a control signal, the light emitting diode of the optocoupler U1 emits light to enable the phototriode of the optocoupler U1 to be switched on, the grid electrode of the first MOS tube becomes low level to further enable the first MOS tube to be cut off, the driving unit cannot enable the driving unit, the driving voltage is not output, and all the MOS switch units are cut off.

In the technical scheme, the driving unit is adopted to output the driving voltage to control all the MOS switch units, the control module can realize the control of all the MOS switch units only by controlling the enabling end of the driving unit through one pin, the connection of all sampling lines is synchronously controlled, the hardware structure is greatly simplified, and otherwise n MOS switches theoretically need n pins to realize the switch control. Meanwhile, the state of the MOS switch unit is completely determined by the output voltage of the driving unit, the MOS switch can be quickly started and closed as long as a reasonable driving voltage is set, and the state of the MOS switch unit is irrelevant to the voltage of the battery, so that the state of the MOS switch unit is suitable for batteries of different types and different battery SOC states; the driving voltage can be properly adjusted within a safety range, the on-resistance of the branch switch is reduced, and the loss and the temperature rise are reduced; in addition, the control module is isolated from the driving unit through the optocoupler, and any state change of the battery end cannot influence the BMS system, so that the safety performance of the BMS system is greatly improved.

In a preferred embodiment, the optical coupler U1 is a PhotoMOS coupler.

In a preferred embodiment, the driving unit uses a switching power supply, and is implemented by controlling an enable terminal (or a ground terminal) of the switching power supply.

In a preferred embodiment, the MOS switch unit is implemented by using an NMOS or a PMOS, wherein a source and a drain of the MOS transistor are connected in series in the sampling line, and a gate of the MOS transistor is connected to an output terminal of the driving unit. Because of the MOS switch, the current can flow in two directions, and the balance control of the BMS system is not influenced; the technical scheme can be theoretically applied to the battery packs with any string number as long as the total voltage of the battery packs is within the safe voltage withstanding range of the MOS switch.

The above description of the embodiments is only intended to help understand the method of the present invention and its core ideas. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.

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. A misconnection protection circuit for battery sampling lines in a BMS system is characterized in that the circuit at least comprises a control module, an enabling control unit, a driving unit, an MOS (metal oxide semiconductor) switch unit and a relay unit, wherein the anode and the cathode of each single battery are connected with the relay unit in parallel, the sensing output ends of all the relay units are connected with a first pin of the control module together, and when any sampling line is connected in a wrong way, the sensing output ends can generate sensing signals; the control module controls the second pin to output a control signal after acquiring the induction signal;

the enabling control unit is connected with a second pin of the control module and the driving unit and is used for temporarily outputting an enabling signal in the future of the control signal to enable the driving unit to output a driving voltage and outputting a non-enabling signal in the future of the control signal to enable the driving unit to close the output;

2. The mis-connection protection circuit of battery sampling line in BMS system as claimed in claim 1, wherein said relay unit is a voltage relay, the input terminal of the relay is connected in parallel to both terminals of the battery cell, and the input loop is connected in series with a third resistor R3 and a first diode D1; output end one end of the relay is connected with the first ground end, and the other end of the relay is connected with the first pin of the control module as the induction output end.

3. The mis-wiring protection circuit of battery sampling lines in the BMS system according to claim 2, wherein the third resistor R3 is a PTC thermistor.

4. The mis-wiring protection circuit of battery sampling lines in the BMS system according to claim 1, wherein the coil of the relay is made of a PTC material.

5. The protection circuit for the misconnection of the battery sampling line in the BMS system according to claim 3 or 4, wherein the enabling control unit comprises an optical coupler U1, a first resistor R1, a second resistor R2 and a first MOS transistor, wherein a light emitter of the optical coupler U1 is controlled by a control signal, one end of a light receiver of the optical coupler U1 is connected with a second ground, the other end of the light receiver is connected with a grid electrode of the first MOS transistor and one end of a first resistor R1, and the other end of a first resistor R1 is connected with a power supply VDD; the source electrode of the first MOS tube is connected with the second ground end, and the drain electrode of the first MOS tube is connected with the enable end of the driving unit.

6. The mis-connection protection circuit for battery sampling lines in the BMS system according to claim 3 or 4, wherein the MOS switch unit is implemented using NMOS or PMOS.

7. The mis-wiring protection circuit of battery sampling lines in the BMS system according to claim 3 or 4, wherein the control module is integrally provided in the BMS system.

8. The battery sampling line misconnection protection circuit in BMS system according to claim 3 or 4, wherein the optocoupler U1 is PhotoMOS coupler.

9. The mis-connection protection circuit of battery sample lines in the BMS system according to claim 3 or 4, wherein the driving unit employs a switching power supply.

10. The mis-connection protection circuit of battery sampling lines in the BMS system according to claim 3 or 4, wherein the control module is implemented using a logic control circuit.