A lithium battery pack safety charging protection method and a charging protection circuit thereof

Abstract

The present application relates to a kind of lithium battery pack safety charging protection method and its charging protection circuit, and encoding circuit judges whether at least one "battery without dedicated state lead output state branch" signal abnormality exists according to multiple "battery without dedicated state lead output state branch" signals, and if at least one "battery without dedicated state lead output state branch" signal abnormality, then encoding circuit output end exports abnormal state signal to charging protection chip;Charging protection chip starts protection control;By this, the problem that the number of pins of the state input of conventional charging protection chip in prior art is not enough can be solved, and more preferably, the host computer judges whether battery charging is abnormal based on battery output state data, and the host computer first calculates the discrimination number p, and whether the discrimination number p satisfies threshold value can be directly judged whether charging circuit is abnormal.

Description

TECHNICAL FIELD

[0001] The present application relates to a lithium battery pack safety charging protection method and its charging protection circuit. BACKGROUND

[0002] The related prior art discloses a lithium battery pack safety charging protection circuit such as Figure 1 The charging protection circuit includes five series lithium batteries B1, B2, B3, B4 and B5, each lithium battery corresponds to a corresponding RC filter circuit 1, U1 is a control chip for realizing signal detection processing, the U1 chip corresponds to five pins VC1, VC2, VC3, VC4 and VC5 as detection signal input ends, which are respectively connected to the output ends of the RC filter circuits 1 respectively connected with the lithium batteries B1, B2, B3, B4 and B5, the CO pin of the U1 chip is connected to the first output circuit 3 as a trigger signal output end, the U1 chip also has a power supply input end VDD and a ground end VSS, the connection mode between the U1 chip, the RC filter circuit 1 and the lithium battery pack is a conventional circuit, and the specific line connection mode is shown in Figure 1, the first output circuit 3 and the second output circuit 5 in the figure are two different sampling circuits, the first output circuit 3 is used for resistance sampling, and the second output circuit 5 is used for temperature sampling, the second output circuit 5 is connected in the self-checking circuit 4, the first output circuit 3 comprises a third resistor R3, a fourth resistor R4, a second field effect transistor Q2 and a recognition resistor Rs, the second output circuit 5 comprises a thermistor RT, the self-checking circuit 4 comprises a first field effect transistor Q1, a first resistor R1, a first capacitor C1, a first diode D1, a second resistor R2 and a second capacitor C2, wherein one end of the third resistor R3 is connected with a CO pin of a U1 chip, the other end of the third resistor R3 is connected with a gate of the second field effect transistor Q2 through the fourth resistor R4, one end of the second field effect transistor Q2 is grounded, the other end of the second field effect transistor Q2 is connected with a first input end ID1 of a charger circuit through the recognition resistor Rs, the drain of the first field effect transistor Q1 is connected with an output end of an RC filter circuit 1 corresponding to a lithium battery, when the lithium battery group is connected with the charger, in a normal working state, the charger reads the resistance value of the recognition resistor Rs through the first input end ID1, and then judges whether the lithium battery is overcharged or whether the wire is disconnected, at the same time, the charger reads the temperature value of the thermistor RT through a second input end ID2, to judge whether the lithium battery group is in a normal temperature value range; when the charger outputs a periodic trigger signal from the second input end ID2, after the first field effect transistor Q1 is turned on, the first lithium battery B1 presents a ground open circuit state, at this time, if the CO pin of the U1 chip originally outputs a normal charging signal (low level), after the first lithium battery B1 is short-circuited to the ground, the CO pin of the U1 chip should generate an output signal change (jump to high level), if the CO pin of the U1 chip does not generate the output signal change after the first lithium battery B1 is short-circuited to the ground, it is indicated that the U1 chip itself (the charging protection circuit itself) or other elements in the circuit are faulty (single failure of the element will cause the CO pin of the U1 chip to output a constant high level or a constant low level, if it is a constant high level, it is indicated that the charging is prohibited, and the circuit cannot normally run;If it is always low, it means that the charging is allowed, and the safety of the charging cannot be guaranteed, therefore, when the CO pin of the U1 chip outputs a constant low level, there is a risk of overcharging, and the charging needs to be stopped immediately and an alarm needs to be given, and in summary, the prior art adds a charging self-checking method on the basis of the conventional lithium battery protection circuit, the starting of the trigger signal and the starting of the charger circuit are synchronous, when the battery pack is connected to the charger to start charging, the charger will regularly send a trigger signal to the charging protection circuit to ensure the self-checking of the circuit during the whole charging process, and safety accidents caused by the fault of the protection circuit itself or the wrong output of the interface circuit can be avoided, and similarly, in the prior art, a trigger point is led out from a branch outputting a state outside the battery in series, if the trigger point is not set and a single battery or a single battery in the branch outputting the state outside the battery has a problem, the problem cannot be detected, because in practice, a group of batteries often need to be connected in series, and when the number of batteries connected in series is large, the number of state input pins of a conventional charging protection chip is not enough, if a large number of charging protection chips are set to solve the problem, not only the cost is high, but also the related lead and control logic need to be modified, and this is also very complex. SUMMARY

[0003] The present application aims to provide a lithium battery pack safety charging protection method and a charging protection circuit to solve the problems in the background art.

[0004] In order to solve the above technical problems, the present application provides the following technical solutions: a lithium battery pack safety charging protection circuit, comprising a charging protection chip, the charging protection chip has N charging state judgment input pins, and further comprising a plurality of battery external output state branches, the number of the battery external output state branches is greater than N, the battery external output state branches are divided into two categories, the first category is a battery external output state branch with a dedicated state lead, and the second category is a battery external output state branch without a dedicated state lead, the number of the battery external output state branch with a dedicated state lead is less than or equal to N-1, the input end of the battery external output state branch with a dedicated state lead is connected to the electrode of a battery, the output end of the battery external output state branch with a dedicated state lead is connected to the charging state judgment input pin of the charging protection chip, the input end of the battery external output state branch without a dedicated state lead is connected to the electrode of a battery, the output end of the battery external output state branch without a dedicated state lead is connected to the input end of an encoding circuit, and the output end of the encoding circuit is connected to at least one charging state judgment input pin of the charging protection chip; the encoding circuit is used for judging whether at least one signal of the battery external output state branch without a dedicated state lead is abnormal according to the input signals of a plurality of battery external output state branches without a dedicated state lead, and the encoding circuit outputs an abnormal state signal to the charging protection chip if at least one signal of the battery external output state branch without a dedicated state lead is abnormal.

[0005] The output end of the further battery external output state branch with a dedicated state lead is connected to the input end of the encoding circuit.

[0006] Further comprising a periodic trigger circuit, and the output end of the periodic trigger circuit is connected to the output end of the encoding circuit.

[0007] Further, the encoding circuit adopts an OR gate logic circuit.

[0008] Further comprising a downward communication circuit, an upper computer and an upload communication circuit, the input end of the upload communication circuit is connected to the output end of the battery external output state branch with a dedicated state lead, the input end of the upload communication circuit is also connected to the output end of the battery external output state branch without a dedicated state lead, the upload communication circuit is used for outputting battery external output state data to the upper computer, the upper computer judges whether the battery charging is abnormal based on the battery external output state data, the upper computer is also used for sending trigger signal data to the downward communication circuit when the battery charging is abnormal, the output end of the downward communication circuit is electrically connected to the charging state judgment input pin of the charging protection chip, and the downward communication circuit generates a trigger signal to the charging protection chip based on the trigger signal data.

[0009] Further described host computer judges whether the battery charging is abnormal based on the battery external output state data, specifically:

[0010] The battery external output state data is the measured output voltage value of each battery external output state branch, the host computer sorts the measured output voltage value of each battery external output state branch according to time and fits it into a function, the horizontal coordinate of the function is the time t, and the vertical coordinate of the function is the measured voltage value, in a judgment period, the host computer first calculates the discriminant p:

[0011] Wherein ti is the time variable, a is the coefficient of adjusting the data sampling period, Mi is the coefficient of adjusting the operation precision, Q is the number of batteries, and the discriminant p specifically represents the second product of the integral quantity of the voltage measured value fitting function on each branch, whether the charging circuit is abnormal can be directly judged by calculating whether the discriminant p meets the threshold value.

[0012] A lithium battery pack safety charging protection method, comprising the steps of:

[0013] The output end of the battery external output state branch without a dedicated state lead outputs a signal to the input end of the encoding circuit;

[0014] The encoding circuit judges whether at least one battery external output state branch without a dedicated state lead signal is abnormal according to the signals of multiple battery external output state branches without a dedicated state lead, and outputs an abnormal state signal to the charging protection chip at the output end of the encoding circuit if at least one battery external output state branch without a dedicated state lead signal is abnormal; the charging protection chip starts protection control.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The output end of the battery external output state branch without a dedicated state lead outputs a signal to the input end of the encoding circuit; the encoding circuit judges whether at least one battery external output state branch without a dedicated state lead signal is abnormal according to the signals of multiple battery external output state branches without a dedicated state lead, and outputs an abnormal state signal to the charging protection chip at the output end of the encoding circuit if at least one battery external output state branch without a dedicated state lead signal is abnormal; the charging protection chip starts protection control; in this way, the problem of insufficient number of state input pins of the conventional charging protection chip in the prior art can be solved, and more preferably, the host computer judges whether the battery charging is abnormal based on the battery external output state data, the host computer first calculates the discriminant p, and whether the charging circuit is abnormal can be directly judged by calculating whether the discriminant p meets the threshold value.

[0017] Figure 1 A schematic diagram of a lithium battery pack safety charging protection circuit in the prior art.

[0018] Figure 2 A schematic diagram of a lithium battery pack safety charging protection circuit in the prior art.

[0019] Figure 3 A schematic diagram of a lithium battery pack safety charging protection circuit in the prior art. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0021] The present application discloses a lithium battery pack safety charging protection circuit, such as Figure 2The application relates to a lithium battery pack safety charging protection method, which comprises the following steps: the output end of a battery external output state branch without a special state lead outputs a signal to the input end of an encoding circuit 2; the encoding circuit 2 judges whether at least one signal of the battery external output state branch without a special state lead is abnormal according to the signals of the multiple battery external output state branches without a special state lead; if at least one signal of the battery external output state branch without a special state lead is abnormal, the encoding circuit 2 outputs an abnormal state signal to a charging protection chip 1; and the charging protection chip 1 starts protection control.

[0022] Therefore, the application further discloses a lithium battery pack safety charging protection method, which comprises the following steps: the output end of a battery external output state branch without a special state lead outputs a signal to the input end of an encoding circuit 2; the encoding circuit 2 judges whether at least one signal of the battery external output state branch without a special state lead is abnormal according to the signals of the multiple battery external output state branches without a special state lead; if at least one signal of the battery external output state branch without a special state lead is abnormal, the encoding circuit 2 outputs an abnormal state signal to a charging protection chip 1; and the charging protection chip 1 starts protection control.

[0023] In the preferred implementation, the battery with the dedicated state lead outputs the state branch output to the input of the encoding circuit 2, so that the state of all batteries can be uniformly determined.

[0024] In the preferred implementation, the circuit further comprises a periodic trigger circuit 3, and the output of the periodic trigger circuit 3 is connected to the output of the encoding circuit 2, so that the self-check of the periodic trigger circuit is realized.

[0025] In the preferred implementation, the application discloses a lithium battery pack safety charging protection circuit, as shown in Figure 3 The application further comprises a downward communication circuit 5, a host computer 6 and an upload communication circuit 4, the input of the upload communication circuit 4 is connected to the output of the state branch output of the battery with the dedicated state lead, the input of the upload communication circuit 4 is also connected to the output of the state branch output of the battery without the dedicated state lead, the upload communication circuit 4 is used to output the state data of the battery to the host computer 6, the host computer 6 is used to determine whether the battery charging is abnormal based on the state data of the battery, the host computer 6 is also used to send a trigger signal data to the downward communication circuit 5 when the battery charging is abnormal, the output of the downward communication circuit 5 is electrically connected to the charging state determination input pin of the charging protection chip 1, and the downward communication circuit 5 generates a trigger signal to the charging protection chip 1 based on the trigger signal data. The data operation of the host computer can expand the problem of less local operation resources, and in the application environment with high safety requirements for charging control, only the expansion of the host computer can meet the requirements.

[0026] The host computer 6 determines whether the battery charging is abnormal based on the state data of the battery output, and the specific steps are as follows:

[0027] The state data of the battery output is the measured value of the output voltage of each state branch output of the battery, and the host computer sorts and fits the measured value of the output voltage of each state branch output of the battery according to time in sequence to obtain a function, the abscissa of the function is the time t, and the ordinate of the function is the measured value of the voltage. In a determination period, the host computer first calculates a discrimination number p:

[0028] Wherein ti is time variable, a is the coefficient of adjusting data sampling period, Mi is the coefficient of adjusting operation precision, Q is the number of batteries, the discriminant p specifically represents the second product (accumulation, each variable participating in accumulation is actually an integral quantity) of the integral quantity of the voltage measured value fitting function on each branch, and whether the charging circuit is abnormal can be directly judged by calculating whether the discriminant p satisfies the threshold value. Because the discriminant p specifically represents the second product of the integral quantity of the voltage measured value fitting function on each branch, the integral quantity of the voltage measured value fitting function on any one battery branch is abnormal, and any abnormal integral quantity of the voltage measured value fitting function will also cause the discriminant p to mutate, so it is easy to judge whether the charging circuit is abnormal.

[0029] More preferably, the discriminant p also changes periodically in multiple judgment periods, so in the preferred implementation, the periodic change of the discriminant p conforms to the general function y=sin n x, n is a natural number, that is, the change period of the discriminant p is equal to the change period of the function y=sin n x, and whether the discriminant p is abnormal can be calculated, and whether the overall change pt of multiple periods pi satisfies the threshold value, that is, the calculation: pt= ((n-1) / n)*∫sin n-2 pidpi-(n-1)*sin n- 1 pi*cospi.

Claims

1. A lithium battery pack safety charging protection circuit, comprising a charging protection chip, characterized in that, The charging protection chip has N charging state judgment input pins, and further comprises a plurality of battery external output state branches, the number of the battery external output state branches is greater than N, the battery external output state branches are divided into two categories, the first category is a battery external output state branch with a dedicated state lead, and the second category is a battery external output state branch without a dedicated state lead, the number of the battery external output state branches with the dedicated state lead is less than or equal to N-1, the input end of the battery external output state branch with the dedicated state lead is connected to the electrode of the battery, the output end of the battery external output state branch with the dedicated state lead is connected to the charging state judgment input pin of the charging protection chip, the input end of the battery external output state branch without the dedicated state lead is connected to the electrode of the battery, the output end of the battery external output state branch without the dedicated state lead is connected to the input end of the encoding circuit, and the output end of the encoding circuit is connected to at least one charging state judgment input pin of the charging protection chip; the encoding circuit is used for judging whether at least one signal of the battery external output state branch without the dedicated state lead is abnormal according to the input signals of the plurality of battery external output state branches without the dedicated state lead, and outputs an abnormal state signal to the charging protection chip if at least one signal of the battery external output state branch without the dedicated state lead is abnormal; further comprising a downward communication circuit, an upper computer and an upload communication circuit, the input end of the upload communication circuit is connected to the output end of the battery external output state branch with the dedicated state lead, the input end of the upload communication circuit is further connected to the output end of the battery external output state branch without the dedicated state lead, the upload communication circuit is used for outputting battery external output state data to the upper computer, the upper computer judges whether the battery charging is abnormal based on the battery external output state data, the upper computer is further used for sending trigger signal data to the downward communication circuit when the battery charging is abnormal, the output end of the downward communication circuit is electrically connected to the charging state judgment input pin of the charging protection chip, and the downward communication circuit generates a trigger signal to the charging protection chip based on the trigger signal data.

2. The lithium battery pack safety charging protection circuit according to claim 1, wherein, The output end of the battery external output state branch with the dedicated state lead is connected to the input end of the encoding circuit.

3. The lithium battery pack safety charging protection circuit according to claim 1, wherein, Further comprising a periodic trigger circuit, and the output end of the periodic trigger circuit is connected to the output end of the encoding circuit.

4. The lithium battery pack safety charging protection circuit according to claim 1, wherein, The encoding circuit adopts an OR gate logic circuit.

5. A method for protecting a lithium battery pack from overcharging using the circuit of claim 1, comprising the steps of: the output terminal of the state output branch of the battery without a dedicated state lead outputting a signal to the input terminal of the encoding circuit; the encoding circuit determining whether there is at least one abnormal signal of the state output branch of the battery without a dedicated state lead based on the signals of the plurality of state output branches of the batteries without a dedicated state lead, and outputting an abnormal state signal to the charging protection chip if there is at least one abnormal signal of the state output branch of the battery without a dedicated state lead; and the charging protection chip starting protection control.

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