CN213547135U - Series battery protection circuit - Google Patents

Abstract

The utility model provides a series battery protection circuit, include: the battery modules are connected in series between the positive electrode and the negative electrode of the battery pack and respectively comprise a single battery, a protection switch and a single battery protection module; the single battery is connected with the protection switch in series, the single battery protection module generates a turn-off signal and protects the current battery module based on the turn-off signal; the shutdown signal level displacement module is used for transmitting the shutdown signal of any stage of battery module to other stages of battery modules; and the voltage transient suppression module is connected between the positive pole and the negative pole of the battery pack and used for absorbing the burr voltage and slowing down the change speed of the total voltage between the positive pole and the negative pole of the battery pack. The utility model discloses reliably realize based on the function of lower withstand voltage charge-discharge switching device protection higher voltage series battery, both protected series battery wholly, protected every section series battery again, the security performance is high, and is with low costs.

Description

Series battery protection circuit

Technical Field

The utility model relates to an integrated circuit design field especially relates to a series battery protection circuit.

Background

With the vigorous promotion of energy conservation and emission reduction and environmental protection trip, new energy automobiles become a great trend, cleaner and more environmental-friendly automobile research and development are devoted globally, and the lithium ion power battery is unprecedentedly developed. However, the inherent fragility of the lithium ion battery brings hidden dangers to a lithium ion power battery automobile, and how to better protect the lithium ion power battery becomes a plurality of long-term goals for engineers. However, to date, the protection of series lithium ion batteries or battery packs has not progressed much, and there is no substantial breakthrough in balancing the cost and the improvement of the protection performance.

A first protection scheme for series-connected batteries is proposed in the prior art, as shown in fig. 1, which includes n-stage batteries connected in series, each battery is connected in series with a protection switching device (S1, S2 … … Sn), and each battery has its own single battery protection module with a protection switching device. If a single battery in the series battery is turned off, the voltages on the two sides of the turned-off protection switch bear all the variable voltages from the total input and output of the series battery, and each protection switch device must be a high-voltage-resistant switch device capable of bearing the total input and output voltages of the series battery to ensure safety. Assuming that the normal output of 13 ternary lithium battery series batteries is 48V, once a short circuit occurs, a certain battery protection switch device in the battery pack is turned off first (because the difference of the protection delay time built in the chip inevitably exists, the protection switch devices of each battery in the battery in series cannot be turned off automatically in the short circuit, and a switch is turned off independently with a high probability), based on the basic principle that the voltages at two ends of the battery are not changed, the node of the turned-off protection switch device connected with the negative end of the high-voltage battery becomes negative (the negative end PK-of the battery is defined as the ground level), the node connected with the positive end of the low-voltage battery becomes positive, the voltage difference at two ends of the protection switch device becomes the output voltage of the whole series battery, namely the voltage difference at two ends of the protection switch device is 48V at the moment. Due to the requirement of voltage resistance, the self-protection switching device of each series-connected battery adopts a switching device with voltage resistance exceeding 48V, such as 80V or even 100V voltage-resistant switching device, and because more than ten or even tens of switching devices are connected in series, the internal resistance of the 80V or even 100V voltage-resistant switching device must be small (even less than 10 milliohms) so as to ensure that the internal resistance is not too large after tens of series-connected batteries are connected in series. This results in a very high cumulative cost of ten or even tens of protection switching devices operating at 48V in the circuit. In addition, if each battery needs to realize accurate current (+/-10% accuracy) protection, high-accuracy and high-power current sampling resistors (Rsns1 and Rsns2 … … Rsns) need to be added into each series battery, and if the application is 400V/500A, each battery needs to be connected with dozens of high-accuracy and high-power current sampling resistors in parallel, and if the total number of the batteries is 100, thousands of the high-accuracy and high-power current sampling resistors are needed; the cost of a single high-precision high-power current sampling resistor is usually nearly 0.5 yuan RMB, and the total cost of thousands of high-precision high-power current sampling resistors is abnormally high and reaches thousands of yuan.

In order to avoid the problem that cost is too high due to the fact that each battery is provided with a high-voltage low-impedance switch device, the current common method is that each battery of the batteries connected in series does not have a switch device and does not have an independent protection module, so that a thermistor (such as Tesla) is used for rough protection on each battery connected in series secondarily, or each battery does not have any protection and does unified combined protection. As shown in fig. 2, a charging switch tube S1 and a discharging switch tube S2 are added to the negative terminal P of the series battery in the prior art, and the discharging switch tube S2 and the charging switch tube S1 are turned off for protection in case of abnormality, and when a certain battery is charged with overvoltage or discharged with undervoltage, the protection signal is transmitted to the chip directly connected to the charging switch tube S1 and the discharging switch tube S2 through the adjacent chip in a stage, and the chip is turned off. The scheme gives up the self protection of each series battery, avoids using a plurality of high-voltage switch tubes and can greatly reduce the cost. However, when a large short-circuit current is discharged between a plurality of batteries connected in series in the present scheme (for example, a metal conductor is shorted at the positive end and the negative end of one battery or a plurality of batteries connected in series due to an accidental impact, as shown in fig. 2), there is no protection capability, and there is no function of preventing the large current from being discharged even if the charging switch tube S1 and the discharging switch tube S2 are turned off. In addition, this scheme has limited the application of series battery equalizer circuit, and every series battery has given up its accurate current protection for can't carry out between the battery if: use of a current equalization circuit of 2.0A or more. Once the slightly larger current balancing circuit is applied, each battery needs to be provided with accurate overcurrent protection so as to avoid damage to the related batteries caused by overcurrent or short circuit caused by failure of the balancing circuit; meanwhile, abnormal short circuit of the connecting wire of the related equalizing circuit requires each series battery to have an accurate overcurrent protection circuit module. The existing mainstream scheme of the series battery cannot be balanced in real time, so that the repair frequency of the series battery pack is too high, and the problem is solved urgently in the battery industry.

By combining the two schemes for analysis, the second scheme has inherent defects which are difficult to make up, but the cost is low; the scheme has complete protection function, but uses a plurality of low-impedance high-voltage charge and discharge switching devices, so the cost is too high. Therefore, how to reduce the cost while ensuring the complete protection function of the series-connected batteries becomes one of the problems to be solved urgently by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

In view of the above shortcomings of the prior art, an object of the present invention is to provide a series battery protection circuit for solving the problem that the protection function and the cost of the series battery in the prior art cannot be taken into consideration.

To achieve the above and other related objects, the present invention provides a series battery protection circuit, which comprises at least:

the battery module comprises a plurality of stages of battery modules, a turn-off signal level displacement module and a voltage transient suppression module, wherein the battery modules are connected between the anode of the battery pack and the cathode of the battery pack in series;

each level of battery module comprises a single battery, a protection switch and a single battery protection module; the single battery is connected with the protection switch in series, the single battery protection module generates a turn-off signal based on a detection signal of the current battery module or an output signal of the turn-off signal level shift module, and controls the protection switch based on the turn-off signal to protect the current battery module;

the shutdown signal level shifting module is connected with each level of battery module and is used for transmitting the shutdown signal of any level of battery module to other levels of battery modules so as to enable each level of battery module to adopt protection operation;

the voltage transient suppression module is connected between the positive pole of the battery pack and the negative pole of the battery pack and used for absorbing burr voltage and slowing down the change speed of the total voltage between the positive pole of the battery pack and the negative pole of the battery pack.

Optionally, the single battery protection module includes a detection unit and a logic processing unit; the detection unit receives the detection signal and generates a corresponding protection signal; the logic processing unit is connected with the detection unit and the output end of the turn-off signal level shift module, and generates a turn-off signal of the current-stage battery module based on the protection signal or the turn-off signals of other-stage battery modules.

More optionally, the detection unit includes one or more combinations of an under-voltage detection subunit, an over-temperature detection subunit, a discharging over-current detection subunit, and a charging over-current detection subunit.

Optionally, each battery module further includes a bypass diode connected in parallel to both ends of the series structure of the single battery and the protection switch; and the anode of the bypass diode is connected with the protection switch, and the cathode of the bypass diode is connected with the single battery.

Optionally, each battery module further includes a voltage dividing resistor connected in parallel to two ends of the protection switch.

Optionally, each battery module further includes a bypass capacitor, where the bypass capacitor is connected in parallel to two ends of the protection switch, or the bypass capacitor is connected in parallel to two ends of a series structure of the single battery and the protection switch.

Optionally, the turn-off signal level shift module includes a first resistor, a second resistor, a darlington current amplifier and transistors corresponding to the battery modules one to one; the first end of each transistor is connected with the anode of a single battery in the corresponding battery module, the second end of each transistor is connected with the cathode of the battery pack through the first resistor, and the control end of each transistor is connected with the turn-off signal of the corresponding battery module; the first end of the Darlington current amplifier is connected with the corresponding battery module and is connected with the anode of the battery pack through the second resistor, the second end of the Darlington current amplifier is connected with the cathode of the battery pack, and the control end of the Darlington current amplifier is connected with the second end of each transistor; wherein, each transistor is a PNP triode or a PMOS tube.

More optionally, the turn-off signal level shift module further includes voltage limiting units corresponding to the battery modules one to one, and each voltage limiting unit includes a current limiting resistor and a zener diode; the first end of the current limiting resistor is connected with the first end of the Darlington current amplifier, and the second end of the current limiting resistor is connected with the corresponding battery module; and the cathode of the Zener diode is connected with the second end of the current-limiting resistor, and the anode of the Zener diode is connected with the cathode of a single battery in the corresponding battery module.

More optionally, the first terminal and the control terminal of each transistor are respectively connected to the corresponding port through a resistor.

More optionally, the darlington current amplifier is replaced by an NPN triode or an NMOS transistor

Optionally, the voltage transient suppression module comprises a capacitor, or a series-parallel structure of a capacitor and a resistor, or a series-parallel structure of a capacitor and an inductor.

More optionally, the protection switch is replaced by a discharge switch and a charge switch which are connected in series; the shutdown signal level displacement module is replaced by a discharge shutdown signal level displacement module and a charge shutdown signal level displacement module which are connected in parallel, the discharge shutdown signal level displacement module receives a shutdown signal of the discharge switch in any one stage of battery module and transmits the shutdown signal to other stages of battery modules, and the charge shutdown signal level displacement module receives a shutdown signal of the charge switch in any one stage of battery module and transmits the shutdown signal to other stages of battery modules.

More optionally, each of the protection switch, the discharging switch and the charging switch includes a plurality of switches connected in parallel.

As described above, the utility model discloses a series battery protection circuit has following beneficial effect:

the series battery protection circuit of the utility model adopts a lower voltage-resistant charge-discharge switching device to realize the protection of the higher voltage series battery, thereby not only protecting the whole series battery, but also protecting each series battery, and simultaneously solving the problem that the short circuit between the series batteries can not be protected, and having high safety performance; furthermore, the utility model discloses a series battery protection circuit adopts low withstand voltage's switching device, cost greatly reduced.

Drawings

Fig. 1 is a schematic circuit diagram of a first prior art series battery protection scheme.

Fig. 2 is a schematic circuit diagram of a second prior art series battery protection scheme.

Fig. 3 is a schematic diagram of the series battery protection circuit according to the present invention.

Fig. 4 is a schematic diagram of another structure of the series battery protection circuit of the present invention.

Fig. 5 is a schematic diagram of another structure of the series battery protection circuit of the present invention.

Fig. 6 is a schematic diagram of another structure of the series battery protection circuit of the present invention.

Description of the element reference numerals

11-1 n first-nth stage battery module

111-1 n1 first-nth single battery protection module

111a detection unit

111b logical processing unit

2-off signal level shift module

2a discharge turn-off signal level shift module

2b charging turn-off signal level shift module

21 Darlington current amplifier

221-22 n first-nth voltage limiting units

3 voltage transient suppression module

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to fig. 3 to 6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the invention in a schematic manner, and only the components related to the invention are shown in the drawings rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, quantity and proportion of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.

Example one

As shown in fig. 3, the present embodiment provides a series battery protection circuit including:

the battery module comprises a plurality of stages of battery modules, a turn-off signal level shift module 2 and a voltage transient suppression module 3.

As shown in fig. 3, each stage of battery module is connected in series between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack.

Specifically, in the present embodiment, n stages of battery modules (n is a natural number greater than or equal to 2, and in actual use, the number of the battery modules is not less than 2 stages) are included, and the battery modules are respectively denoted as a first stage battery module 11 and a second stage battery module 12 …, and the battery modules of the respective stages are sequentially connected in series. The first-stage battery module 11 includes a first single battery Bat1, a first protection switch K1, and a first single battery protection module 111.

More specifically, the first single battery Bat1 is connected in series with the first protection switch K1; as an example, the positive electrode B1+ of the first single battery Bat1 is used as the positive electrode PK1+ of the first stage battery module 11, the first end of the first protection switch K1 is connected to the negative electrode B1 "of the first single battery Bat1, and the second end of the first protection switch K1 is used as the negative electrode PK 1" of the first stage battery module 11 and is connected to the battery negative electrode PK-.

More specifically, the first single-battery protection module 111 generates a first turn-off signal based on the detection signal of the first-stage battery module 11 or the output signal of the turn-off signal level shift module 2, and controls the first protection switch K1 to turn off or on based on the first turn-off signal, so as to protect the first battery module 11. As an example, the first single battery protection module 111 includes a detection unit 111a and a logic processing unit 111 b. The detection unit 111a receives a detection signal and generates a corresponding protection signal, and the detection unit 111a includes, but is not limited to, one or more combinations of an under-voltage detection sub-unit CMP1, an over-voltage detection sub-unit CMP2, an over-temperature detection sub-unit OT, an over-discharge current detection sub-unit CMP3, and an over-current detection sub-unit CMP 4; in this embodiment, the under-voltage detection subunit CMP1 is connected to the positive electrode B1+ of the first single battery Bat1, and compares the positive electrode voltage of the first single battery Bat1 with a first reference voltage Vref1 to determine whether the first single battery Bat1 is under-voltage, and outputs a corresponding under-voltage protection signal; the overvoltage detection subunit CMP2 is connected to the positive electrode B1+ of the first single battery Bat1, and compares the positive electrode voltage of the first single battery Bat1 with a second reference voltage Vref2 to determine whether the first single battery Bat1 is overvoltage or not, and outputs a corresponding overvoltage protection signal; the over-temperature detection subunit OT judges whether the first single battery Bat1 is over-temperature based on an internal temperature detection device, and outputs a corresponding over-temperature protection signal; the over-discharge current detection subunit CMP3 is connected to the negative electrode B1 "of the first single battery Bat1, converts the negative electrode current of the first single battery Bat1 into an induced voltage, compares the induced voltage with a third reference voltage Vref3 to determine whether the discharge current of the first single battery Bat1 is too large, and outputs a corresponding over-current discharge protection signal; the overcharge current detection subunit CMP4 is connected to the second terminal of the first protection switch K1, converts the current of the second terminal of the first protection switch K1 into an induced voltage, compares the induced voltage with a fourth reference voltage Vref4 to determine whether the charging current of the first single battery Bat1 is too large, and outputs a corresponding overcurrent charging protection signal. The logic processing unit 111b is connected to the detection unit 111a and the output end of the shutdown signal level shift module 2, and generates a shutdown signal (first shutdown signal) of the first-stage battery module 11 based on each protection signal or a shutdown signal of another-stage battery module.

It should be noted that the number, types, and connection relationships of the detecting sub-units in the detecting unit 111a may be set based on actual needs, and are not limited to this embodiment. The negative electrode PK 2-of the second-stage battery module 12 is connected with the positive electrode PK1+ of the first-stage battery module 11 and comprises a second single battery Bat2, a second protection switch K2 and a second single battery protection module 121. By analogy, the negative electrode PKn-of the nth-stage battery module 1n is connected with the positive electrode of the preceding stage, and the positive electrode PKn + of the nth-stage battery module 1n is connected with the positive electrode PK + of the battery pack and comprises an nth single battery Batn, an nth protection switch Kn and an nth single battery protection module 1n 1. In this embodiment, the first-stage battery module 11 is taken as an example for specific description, and the structure and principle of each stage of battery module are the same, which are not repeated herein.

It should be noted that the overdischarge current detection subunit CMP3 and the overcharge current detection subunit CMP4 of this embodiment are implemented by using the "charge-discharge overcurrent protection circuit" (application No. 201921942910.6) of the chinese patent authorized by the applicant, and the high-precision charge-discharge overcurrent protection of each single battery can be implemented without adding a high-precision high-power current sampling resistor, so as to greatly save the cost, thereby further making the utility model discloses under the condition of approaching the cost of the existing scheme, the optimization and the protection performance of realizing the protection of the series battery are greatly improved, thereby not only protecting the whole series battery, but also protecting each battery.

As shown in fig. 3, the shutdown signal level shift module 2 is connected to each stage of battery module, and is configured to transmit a shutdown signal of any stage of battery module to each other stage of battery module, so that each stage of battery module takes protection operation.

Specifically, in the present embodiment, the shutdown signal level shift module 2 includes a first resistor R _1, a second resistor R _2, a darlington current amplifier 21 and transistors (a first transistor Q1, a second transistor Q2 …, an nth transistor Qn) corresponding to the battery modules one by one. As an example, each transistor adopts a PNP triode, and in practical use, transistors that are turned on when the control terminal receives a low level are all suitable for the present invention, including but not limited to a triode and an MOS transistor, which are not repeated herein; the collector of the first transistor Q1 is connected to the battery pack cathode PK-via the first resistor R _1, the base is connected to the first turn-off signal, and the emitter is connected to the anode B1+ of the first battery Bat 1; similarly, the collector of the nth transistor Qn of the second transistor Q1 … is connected to the negative electrode PK of the battery pack through the first resistor R _1, the base is connected to the turn-off signal of the corresponding battery module, and the emitter is connected to the positive electrode of the corresponding single battery. The first end of the Darlington current amplifier 21 is connected with the corresponding battery module and is connected with the positive electrode PK + of the battery pack through the second resistor R _2, the second end of the Darlington current amplifier is connected with the negative electrode PK-of the battery pack, and the control end of the Darlington current amplifier is connected with the second end of each transistor; as an example, the darlington current amplifier 21 includes a first NPN transistor Q11 and a second NPN transistor Q12, a collector of the first NPN transistor Q11 is connected to a collector of the second NPN transistor Q12 and serves as a first end of the darlington current amplifier 21, a base of the first NPN transistor Q11 serves as a control end of the darlington current amplifier 21, an emitter of the first NPN transistor Q11 is connected to a base of the second NPN transistor Q12, and an emitter of the second NPN transistor Q12 is connected to the battery pack negative electrode PK-.

As another implementation of the present invention, the first end and the control end of each transistor respectively correspond to the port via a resistor. In this embodiment, the base of the first transistor Q1 is connected to the turn-off signal of the first stage battery module 11 via a resistor R11, and the emitter is connected to the positive electrode B1+ of the first battery Bat1 via a resistor R12; the base of the second transistor Q2 is connected with the turn-off signal of the second-stage battery module 12 through a resistor R21, and the emitter is connected with the positive electrode B2+ of the second single battery Bat2 through a resistor R22; the base of the nth transistor Qn is connected to the turn-off signal of the nth battery module 1n via a resistor Rn1, and the emitter thereof is connected to the positive electrode Bn + of the nth battery Batn via a resistor Rn 2.

As another implementation manner of the present invention, the turn-off signal level shift module 2 further includes voltage limiting units corresponding to the battery modules one-to-one, which are respectively recorded as the nth voltage limiting unit 22n of the first voltage limiting unit 221 and the second voltage limiting unit 222 …. The first voltage limiting unit 221 includes a first current limiting resistor RL1 and a first zener diode ZD1, a first end of the first current limiting resistor RL1 is connected to a first end of the darlington current amplifier 21, and a second end is connected to the logic processing unit 111b of the first-stage battery module 11; the cathode of the first zener diode ZD1 is connected with the second end of the first current-limiting resistor RL1, and the anode of the first zener diode ZD1 is connected with the cathode B1-of the first single battery Bat 1. The second voltage limiting unit 222 includes a second current limiting resistor RL2 and a second zener diode ZD2, and is connected between the second stage battery module 12 and the first end of the darlington current amplifier 21; in this way, the nth voltage limiting unit 22n includes an nth current limiting resistor RLn and an nth zener diode ZDn connected between the nth battery module 1n and the first end of the darlington current amplifier 21; in this embodiment, the first voltage limiting unit 221 is only taken as an example for specific description, and the structures and principles of the voltage limiting units of each stage are the same, which are not repeated herein.

Specifically, if an abnormality occurs in a certain battery in the series-connected batteries, the corresponding single battery protection module outputs an off signal (normally, from a high level to a low level) to turn off the protection switch thereof, and at the same time, the base level of the corresponding transistor in the off signal level shift module 2 is pulled low, the transistor is turned on, current flows in from the emitter of the transistor and flows out to the first resistor R _1 through the collector, when the voltage across the first resistor R _1 is higher than Vbe _ Q11+ Vbe _ Q12 (about 1.4V as an example), the darlington current amplifier 21 is turned from off to on, the voltage of the first terminal of the NPN current amplifier 21 (the collector of the first transistor Q11 and the collector of the second transistor Q12) is pulled low (as low as 0.5V or lower), and the forced off input terminal of the other single battery protection modules (the connection port of the darlington current amplifier 21 and the corresponding logic processing unit) is changed from a normal high level to a low level, and correspondingly generating turn-off signals of other protection switches so as to protect each stage of battery module connected in series.

Meanwhile, in order to clamp that the voltage output by the shutdown signal level shift module 2 to each stage of battery module is not too high or too low compared with the voltage of the battery, a current limiting resistor and a zener diode (for example, a 5V zener diode) are used to realize voltage limitation, the highest input voltage is limited to VBn +5V (corresponding to the negative terminal voltage VBn of the single battery plus +5V), the lowest input voltage is limited to VBn-0.7V (corresponding to the negative terminal voltage VBn of the single battery minus 0.7V, and if the voltage is the first battery, the lowest input voltage is limited to 0V); the current limiting resistor limits the current flowing through the clamping zener diode, for example, in a 400V battery application, if an abnormality occurs, the voltage at the first end of the darlington current amplifier 21 is reduced to 0.5V or lower, the voltage at the negative end of the highest-level (nth-level) single battery in the series-connected batteries is 396V (single battery voltage 4.0V), and the voltage difference between the two ends of the nth current limiting resistor RLn in the nth voltage limiting unit 22n is 396V-0.7V (forward conduction voltage of the zener diode is 0.7V) ═ 395.3V. In order to avoid the excessive discharge current of the battery itself during abnormal shutdown, the resistance of the nth current limiting resistor RLn should be large enough, and 10 mega ohms is selected in this embodiment. When the nth current limiting resistor RLn is 10 megohms, 395.3V divided by 10 megohms is 39.5 μ a; that is, when the battery is abnormal, in the off state, the self-discharge of the highest-voltage battery of the series battery is 39.5 μ a here.

It should be noted that, in this embodiment, the turn-off signal level shift module 2 is formed by low-cost devices such as a triode, a resistor, a zener diode, and the like, so that the cost can be greatly reduced.

As shown in fig. 3, the voltage transient suppression module 3 is connected between the positive battery PK + and the negative battery PK-for absorbing the glitch voltage and slowing down the rate of change of the total voltage between the positive battery PK + and the negative battery PK-.

Specifically, in practical application, all protection switches need to be turned off, and there is a time delay therebetween, and meanwhile, there is a time delay of hundreds of nanoseconds or even microseconds when the signal level shift module 2 is turned off. The voltage transient suppression module 3 can provide stable total voltage between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack, avoid a large voltage difference generated by a large current (such as 200A) on two sides of a series switch which is turned off during a time delay, assist in realizing that the voltage on two sides of each turned-off protection switch does not change suddenly, and in a time period from the turning-off of a first protection switch to the turning-off of a last protection switch, the voltage rising amplitude of the voltage transient suppression module 3 is smaller than the voltage difference value between the withstand voltage value of a switching device and the voltage value of a single battery. The voltage transient suppression module 3 provides more time for all protection switches connected in series between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack to realize total turn-off, and provides a gentle voltage environment for all devices connected in series between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack to equally divide the total voltage of the batteries connected in series (the voltage between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack).

Specifically, in this embodiment, the voltage transient suppression module 3 includes a capacitor C, one end of the capacitor C is connected to the positive electrode PK + of the battery pack, and the other end is connected to the negative electrode PK-. In practical use, voltage transient suppression module 3 includes but not limited to the series-parallel structure of electric capacity and resistance, the series-parallel structure of electric capacity and inductance, is not limited to the circuit structure that this embodiment lists, and the arbitrary circuit structure that can absorb burr voltage and slow down the rate of change of total voltage between the anodal PK + of group battery and the group battery negative pole PK-all is suitable for the utility model discloses.

The working principle of the series battery protection circuit of the present embodiment is as follows:

during charging, if a certain battery detects an abnormality, the single battery protection module corresponding to the battery turns off the protection switch of the battery, and simultaneously, the turn-off signal level shift module 2 transmits the turn-off signal to all other batteries in series connection, and turns off the protection switches of the other batteries in series connection. At this time, all the protection switches of the series-connected batteries are in an off state, and under the action of the voltage transient suppression module 3, the total input charging voltage of the series-connected batteries cannot be transient, and the total input charging voltage is distributed to each series-connected battery and the protection switch in the off state; after voltage distribution, the voltage withstand requirement of the protection switch is greatly reduced at this time, and a switching device with lower voltage withstand can be used. If the voltage, internal resistance and other properties of each series battery are completely the same, and the properties of the series protection switches are also completely the same, the total input charging voltage is equally divided between each series battery and the protection switch in the off state.

During discharging, if a certain battery detects abnormality, the single battery protection module corresponding to the battery turns off the protection switch of the battery, and simultaneously, the turn-off signal level shift module 2 transmits the turn-off signal to all other batteries in series connection, and turns off the protection switches of the other batteries in series connection. At this time, all the protection switches of the series-connected batteries are in an off state, under the action of the voltage transient suppression module 3, the total output voltage of the series-connected batteries cannot be subjected to transient, and the total output charging voltage is distributed to each series-connected battery and the protection switch in the off state until the total output voltage of the series-connected batteries is attenuated to zero; after voltage distribution, the voltage withstand requirement of the protection switch is greatly reduced at the moment, and a switching device with lower voltage withstand can be used. If the voltage, internal resistance and other attributes of each series battery are completely the same, and the attributes of the series charging switches are also completely the same, the total output charging voltage is equally divided between each series battery and the protection switch in the off state.

Example two

As shown in fig. 4, the present embodiment provides a series battery protection circuit, which is different from the first embodiment in that each battery module further includes a bypass diode, a voltage-dividing resistor, and a bypass capacitor.

As an implementation of the present invention, each battery module further includes a parallel connection between the single battery and the bypass diodes at the two ends of the series structure of the protection switch, so as to improve the safety redundancy of the transient current mutation. Specifically, as shown in fig. 4, a first bypass diode D1 is connected in parallel across the series structure of the first single battery Bat1 and the first protection switch K1, the anode of the first bypass diode D1 is connected to the second end of the first protection switch K1, and the cathode is connected to the positive electrode B1+ of the first single battery Bat 1; similarly, the anode of the second bypass diode D2 is connected to the second terminal of the second protection switch K2, and the cathode is connected to the positive electrode B2+ of the second single battery Bat 2; in this way, the anode of the nth bypass diode Dn is connected to the second terminal of the nth protection switch Kn, and the cathode is connected to the positive electrode Bn + of the nth single battery Batn.

Specifically, each bypass diode is used for realizing the follow current discharge after the corresponding protection switch is turned off, so that the requirement on the withstand voltage of the protection switch of each battery is reduced; meanwhile, the battery without abnormality can be selected to continue power supply, and the protection switch can also be selected to be turned off. During discharging, if a certain battery detects abnormality, the single battery protection module of the battery turns off the protection switch of the battery, at the moment, the series loop is provided with a diode connected in parallel with the positive ends of two adjacent batteries, the discharging current does not pass through the battery and the protection switch which are turned off, but passes through the diode connected in parallel with the positive ends of the two adjacent batteries, and due to the bypass effect of the diode, the voltage change of the two ends of the turned-off protection switch is smaller than the sum of the voltage of the single battery and the forward conduction voltage of the bypass diode (the diode with proper current is selected, and the voltage can be ensured to be smaller than 10V under the condition of low cost), so the voltage-resistant requirement is greatly reduced; namely, after a diode connected in parallel with the positive ends of two adjacent series batteries is added to each series battery, a switching device with lower withstand voltage can be used for a discharge switch of each series battery; the diodes connected in parallel to the positive terminals of the two adjacent batteries need to be selected to meet the actual current requirement of the application circuit, which is not described herein.

As another implementation of the present invention, each battery module further includes a voltage dividing resistor connected in parallel at both ends of the protection switch. Specifically, as shown in fig. 4, a first voltage dividing resistor R1 is connected in parallel across the first protection switch K1, a second voltage dividing resistor R2 is connected in parallel across the second protection switch K2, and an nth voltage dividing resistor Rn is connected in parallel across the nth protection switch Kn.

Specifically, when all the protection switches are turned off by each voltage dividing resistor, the total input and output voltage of the series-connected batteries can be better divided equally to each battery and each protection switch, so that floating nodes are avoided, the size of the voltage dividing resistor is determined by the self-discharge current of the series-connected batteries, and the detailed description is omitted here.

As another implementation of the present invention, each battery module further includes a bypass capacitor for suppressing induced electromotive force caused by parasitic inductance formed by a longer metal connection between two batteries or two battery packs, resulting in a large voltage difference generated when the protection switch of the battery is turned off. As an example, the bypass capacitors are connected in parallel to two ends of the protection switch, as shown in fig. 4, a first bypass capacitor C1 is connected in parallel to two ends of the first protection switch K1, a second bypass capacitor C2 is connected in parallel to two ends of the second protection switch K2, and an nth bypass capacitor Cn is connected in parallel to two ends of the nth protection switch Kn. As another example, the bypass capacitors are connected in parallel to two ends of the series structure of the single battery and the protection switch, that is, each bypass capacitor is connected in parallel to two ends of the corresponding bypass diode, which is not described herein again. In this embodiment, each bypass capacitor is a ceramic chip capacitor of 1 μ F to 10 μ F, and in practical use, capacitors of different capacities and types can be selected based on practical design requirements, which is not limited to this embodiment.

EXAMPLE III

As shown in fig. 5, the present embodiment provides a series battery protection circuit, which is different from the second embodiment in that the protection switch is replaced by a discharging switch and a charging switch connected in series, and correspondingly, the turn-off signal of the discharging switch has a self-independent discharging turn-off signal level shifting module 2a, and the turn-off signal of the charging switch also has a self-independent charging turn-off signal level shifting module 2 b.

Specifically, the first charging switch K1a and the first discharging switch K1B in the first stage battery module 11 are connected in series and then connected to the negative electrode B1 "of the first single battery Bat1, and the positions of the first charging switch K1a and the first discharging switch K1B can be interchanged, which is not limited in this embodiment. The second protection switch K2 is replaced by a second charging switch K2a and a second discharging switch K2b in the second-stage battery module 12, and the nth protection switch Kn is replaced by an nth charging switch Kna and an nth discharging switch Knb in the nth-stage battery module 1 n. And each turn-off signal is transmitted to the control end of each switch through a driving stage.

Specifically, correspondingly, the turn-off signal of each charging switch is transmitted to the charging turn-off signal level shift module 2b, and is transmitted to other battery modules based on the charging turn-off signal level shift module 2 b; the turn-off signal of each discharge switch is transmitted to the discharge turn-off signal level shift module 2a, and is transmitted to other battery modules based on the discharge turn-off signal level shift module 2 a; the circuit structures of the discharge shutdown signal level shift module 2a and the charge shutdown signal level shift module 2b are the same as the shutdown signal level shift module 2 (the device labels in the discharge shutdown signal level shift module 2a and the charge shutdown signal level shift module 2b are in one-to-one correspondence with the shutdown signal level shift module 2, and are distinguished by suffixes a and b), which is not repeated herein.

As another implementation manner of the present invention, the darlington current amplifier 21 is replaced by an NPN transistor, as shown in fig. 5, the emitter of the NPN transistor is connected to the negative electrode PK ″ of the battery pack, the second end of each transistor is connected to the base, and the collector is connected to the corresponding battery module and connected to the positive electrode PK + of the battery pack via the second resistor (R _2, R _2a or R _2 b).

Example four

As shown in fig. 6, the present embodiment provides a series battery protection circuit, which is different from the third embodiment in that a transistor is replaced by a MOS transistor. Specifically, each PNP triode is replaced by a PMOS transistor, and each NPN triode is replaced by an NMOS transistor, and the specific connection relationship is not repeated herein.

It should be noted that, as an example, each protection switch, discharge switch and charge switch all include a plurality of parallelly connected switches, the quantity of parallelly connected switch sets up based on the electric current that flows through, and it is repeated to omit here.

If there are n the same series device in the series circuit, the voltage at every series device both ends will be the basic series circuit bleeder mechanism of 1/n of whole series circuit voltage, the utility model discloses a every series battery is equipped with same single section battery protection module and protection switch, takes place the abnormal protection when certain economize on electricity pond, when turn-offs this economize on electricity pond protection switch, should turn-off the signal and send other series batteries to through turn-off signal level displacement module 2 to turn-off the protection switch of other series batteries immediately. At the moment, all the switches in the series batteries are in an off state, and according to the voltage division principle of the series circuit, the total voltage of the n series batteries is distributed to n identical units consisting of the single batteries connected in series and the protection switches in the off state, and the voltage on two sides of each identical unit is 1/n of the total voltage of the series batteries. For example, if 100 ternary lithium ion series batteries output a voltage of 370V to 420V in total, and all switches are turned off, then there are 100 identical cells in total, and the voltage distributed to a single cell is 420V ÷ 100 ═ 4.2V. In practical applications, 420V application often generates 420V induced electromotive force, that is, a total voltage of 420+ 420V to 840V is generated, and the voltages equally divided in 100 same cells are: 840 ÷ 100 ═ 8.4V. Considering that the maximum voltage fluctuation of the single battery is from 0V to 4.5V, namely the working voltage of the protection switch is 8.4V, and then more than 50% of withstand voltage safety redundancy is superposed, the withstand voltage value of the protection switch of the single battery is set to be 13V, which is far smaller than the withstand voltage value of the switching device in the first scheme. Based on the condition that all the protection switches can be turned off at the same time, analysis shows that the 13V voltage-resistant charge-discharge switch device is used in each series battery, so that the lithium ion series battery with the voltage as high as 420V can be protected. In practical application, the turn-off signal level shift module 2 has time delay difference of hundreds of nanoseconds to microseconds, so that all switches can be turned off, and the protection reliability is affected by the burr voltage caused by the large-current turn-off.

In order to avoid the time delay difference existing in the turn-off signal level shift module 2 from causing huge voltage difference on two sides of a protection switch of a certain battery when large current is applied, a high-voltage large capacitor (voltage transient suppression module 3) is connected between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack so as to suppress the transient voltage change caused by short-circuit current of hundreds of amperes. According to the withstand voltage value of the protection switch, the capacitance value of the high-voltage large capacitor is calculated as follows: assuming that the charging and discharging current limit or the short-circuit current limit is increased from 1A to 500A instantaneously, the delay time difference of the turn-off signal level shift module 2 is 2 μ s, the protection switch withstand voltage value of each battery protection module is 13V, the voltage of a single battery is 4.2V, and the capacitance value C ═ Δ I ═ t/Δ V of the high-voltage large capacitor is (500A-1A) × 2us/(13V-4.2V) ═ 113.4 μ F according to the formula Δ I × t ═ C ═ Δ V. And (4) considering factors such as fluctuation of the capacitance value caused by the ambient temperature and attenuation of the capacitance value in long-time use, reserving 100% redundancy calculation, and selecting the high-voltage large capacitor with the value of 220 muF. Of course, other devices can be selected for realizing the function of suppressing voltage transient of the utility model, and the utility model still belongs to the scope of the patent claims.

220 muF large capacitors are connected in parallel between the positive electrode PK + of the battery pack and the negative electrode PK-of the battery pack, so long as the switching devices on all the batteries connected in series are in an off state within the time difference of 2 mus, and after 100 voltage-withstanding switch protection devices (including a protection switch or a discharging switch and a charging switch connected in series) and a single battery form the same unit connected in series, the protection of the batteries connected in series at high voltage of 400V can be realized.

To sum up, the utility model provides a series battery protection circuit, include: the battery module comprises a plurality of stages of battery modules, a turn-off signal level displacement module and a voltage transient suppression module, wherein the battery modules are connected between the anode of the battery pack and the cathode of the battery pack in series; each level of battery module comprises a single battery, a protection switch and a single battery protection module; the single battery is connected with the protection switch in series, the single battery protection module generates a turn-off signal based on a detection signal of the current battery module or an output signal of the turn-off signal level shift module, and controls the protection switch based on the turn-off signal to protect the current battery module; the shutdown signal level shifting module is connected with each level of battery module and is used for transmitting the shutdown signal of any level of battery module to other levels of battery modules so as to enable each level of battery module to adopt protection operation; the voltage transient suppression module is connected between the positive pole of the battery pack and the negative pole of the battery pack and used for absorbing burr voltage and slowing down the change speed of the total voltage between the positive pole of the battery pack and the negative pole of the battery pack. The utility model discloses reliably realize based on lower withstand voltage charge-discharge switch device protects the function of higher voltage series battery, and under the condition that is close with current scheme cost, the utility model discloses both protected series battery (or series battery group) wholly, protected every series battery (or every series battery group) again, compared current scheme and increased protect the function, promoted the security performance of series battery (or series battery group) by a wide margin. Meanwhile, the problem that short circuit between series-connected batteries cannot be protected in the existing mainstream protection scheme is solved. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (13)

1. A series battery protection circuit, characterized in that it comprises at least:

the battery module comprises a plurality of stages of battery modules, a turn-off signal level displacement module and a voltage transient suppression module, wherein the battery modules are connected between the anode of the battery pack and the cathode of the battery pack in series;

each level of battery module comprises a single battery, a protection switch and a single battery protection module; the single battery is connected with the protection switch in series, the single battery protection module generates a turn-off signal based on a detection signal of the current battery module or an output signal of the turn-off signal level shift module, and controls the protection switch based on the turn-off signal to protect the current battery module;

the shutdown signal level shifting module is connected with each level of battery module and is used for transmitting the shutdown signal of any level of battery module to other levels of battery modules so as to enable each level of battery module to adopt protection operation;

the voltage transient suppression module is connected between the positive pole of the battery pack and the negative pole of the battery pack and used for absorbing burr voltage and slowing down the change speed of the total voltage between the positive pole of the battery pack and the negative pole of the battery pack.

2. The series battery protection circuit of claim 1, wherein: the single battery protection module comprises a detection unit and a logic processing unit; the detection unit receives the detection signal and generates a corresponding protection signal; the logic processing unit is connected with the detection unit and the output end of the turn-off signal level shift module, and generates a turn-off signal of the current-stage battery module based on the protection signal or the turn-off signals of other-stage battery modules.

3. The series battery protection circuit of claim 2, wherein: the detection unit comprises one or more combinations of an under-voltage detection subunit, an over-temperature detection subunit, a discharge over-current detection subunit and a charge over-current detection subunit.

4. The series battery protection circuit of claim 1, wherein: each battery module also comprises a bypass diode connected in parallel at two ends of the series structure of the single battery and the protection switch; and the anode of the bypass diode is connected with the protection switch, and the cathode of the bypass diode is connected with the single battery.

5. The series battery protection circuit of claim 1, wherein: each battery module also comprises a divider resistor connected in parallel at two ends of the protection switch.

6. The series battery protection circuit of claim 1, wherein: each battery module further comprises a bypass capacitor, and the bypass capacitors are connected in parallel at two ends of the protection switch, or the bypass capacitors are connected in parallel at two ends of a series structure of the single battery and the protection switch.

7. The series battery protection circuit of claim 1, wherein: the turn-off signal level displacement module comprises a first resistor, a second resistor, a Darlington current amplifier and transistors which correspond to the battery modules one to one; the first end of each transistor is connected with the anode of a single battery in the corresponding battery module, the second end of each transistor is connected with the cathode of the battery pack through the first resistor, and the control end of each transistor is connected with the turn-off signal of the corresponding battery module; the first end of the Darlington current amplifier is connected with the corresponding battery module and is connected with the anode of the battery pack through the second resistor, the second end of the Darlington current amplifier is connected with the cathode of the battery pack, and the control end of the Darlington current amplifier is connected with the second end of each transistor; wherein, each transistor is a PNP triode or a PMOS tube.

8. The series battery protection circuit of claim 7, wherein: the turn-off signal level displacement module also comprises voltage limiting units which correspond to the battery modules one by one, and each voltage limiting unit comprises a current limiting resistor and a Zener diode; the first end of the current limiting resistor is connected with the first end of the Darlington current amplifier, and the second end of the current limiting resistor is connected with the corresponding battery module; and the cathode of the Zener diode is connected with the second end of the current-limiting resistor, and the anode of the Zener diode is connected with the cathode of a single battery in the corresponding battery module.

9. The series battery protection circuit of claim 7, wherein: the first end and the control end of each transistor are respectively connected with the corresponding ports through a resistor.

10. The series battery protection circuit of claim 7, wherein: the Darlington current amplifier is replaced by an NPN triode or an NMOS tube.

11. The series battery protection circuit of claim 1, wherein: the voltage transient suppression module comprises a capacitor, or a series-parallel connection structure of the capacitor and a resistor, or a series-parallel connection structure of the capacitor and an inductor.

12. The series battery protection circuit according to any one of claims 1 to 11, characterized in that: the protection switch is replaced by a discharge switch and a charge switch which are connected in series; the shutdown signal level displacement module is replaced by a discharge shutdown signal level displacement module and a charge shutdown signal level displacement module which are connected in parallel, the discharge shutdown signal level displacement module receives a shutdown signal of the discharge switch in any one stage of battery module and transmits the shutdown signal to other stages of battery modules, and the charge shutdown signal level displacement module receives a shutdown signal of the charge switch in any one stage of battery module and transmits the shutdown signal to other stages of battery modules.

13. The series battery protection circuit of claim 12, wherein: each protection switch, each discharge switch and each charge switch comprise a plurality of switches connected in parallel.

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