CN203839985U - Cell discharge overcurrent protection circuit - Google Patents
Cell discharge overcurrent protection circuit Download PDFInfo
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- CN203839985U CN203839985U CN201320828682.6U CN201320828682U CN203839985U CN 203839985 U CN203839985 U CN 203839985U CN 201320828682 U CN201320828682 U CN 201320828682U CN 203839985 U CN203839985 U CN 203839985U
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Abstract
The utility model discloses a cell discharge overcurrent protection circuit. The overcurrent protection circuit comprises a discharge switch tube, a discharge control module used for detecting discharge current of a cell in real time and a time-delay module used for determining whether overcurrent timeout occurs by comparing time of overcurrent generation with the preset time-delay time. Whether overcurrent occurs is determined by comparing the detected discharge current with a preset threshold, if the overcurrent does not occur, the discharge switch tube is controlled to open; and if the overcurrent occurs, and the overcurrent timeout occurs, the discharge switch tube is locked in a turn-off state. Through enforcement of the technical scheme, when a load is connected with a cell, the transient current during cell discharge can be reduced, transient energy during cell discharge is effectively restricted, and safety of the cell is improved.
Description
Technical Field
The utility model relates to a battery protection field especially relates to a battery discharge's overcurrent protection circuit.
Background
After the battery of the electronic equipment powered by the battery is replaced for many times, the phenomenon that the contact of the battery pole piece is blackened is mostly generated, so that the electronic equipment is electrified unreliability. The main reason for this is that the discharge current of the battery is not reasonably controlled. For example, when a battery is replaced in an electronic device, a large pulse current is generated at the moment when a battery pole piece is in contact with a battery holder of the electronic device, and a contact of the battery pole piece is ignited to generate high-temperature oxidation, so that the contact of the battery pole piece is blackened. For safety, the handheld electronic device used in some flammable and explosive environments needs to limit the energy discharged by the battery within a certain safety value. The transient large current discharged by the battery has potential safety hazards on storage and use of the battery, so how to reasonably limit the current discharged by the battery within a safe limit value without influencing normal use is an important technical problem to be solved for battery protection.
At present, the current overcurrent protection of battery discharge mainly adopts the following modes: in the idle state of the battery, the discharge switch tube is normally open. In the discharging process, after the protection circuit detects that the discharging current of the battery exceeds a designed threshold value, the discharging switch tube is turned off after delaying for a certain time, and the discharging of the battery is stopped. During the time of the turn-off delay, the discharge switch tube is continuously turned on, and a large pulse current is arranged on a discharge path. The disadvantage of this method is that the safety of battery use is incompatible with the delay time requirements for charging the capacitive load. If the delay time is designed to be shorter, the turn-off delay time is required to be longer when a load containing a large capacitor is electrified, and if the delay time is not enough, the capacitor of the load is not fully charged yet, the battery protection circuit generates current-limiting protection to stop discharging, and the load cannot be normally electrified. If the delay time is designed to be longer, the charging requirement of a large capacitance load is met, but if a discharging port of a battery is suddenly short-circuited, large pulse current can be generated, and the hidden danger of accidents such as fire disasters or human body burns is caused. With such batteries, the equipment often has the phenomenon of poor contact caused by oxidation and blackening of the contacts of the battery pole pieces.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model lies in, can not provide a battery discharge's overcurrent protection circuit with the defect of the electric current restriction of battery discharge in safe limit value to the aforesaid of prior art, can be well with the electric current restriction of battery discharge in safe limit value.
The utility model provides a technical scheme that its technical problem adopted is: an overcurrent protection circuit for battery discharge is constructed, including a discharge switch tube connected in a battery discharge path, the overcurrent protection circuit further comprising:
the device is used for detecting the discharge current of the battery in real time, judging whether overcurrent occurs or not by comparing the detected discharge current with a preset threshold value, and controlling the discharge switch tube to be switched on if the overcurrent does not occur; if the overcurrent happens, the discharge switch tube is controlled to be turned off, and in the overcurrent timeout, the discharge switch tube is locked in a discharge control module in a turn-off state;
and the delay module is connected with the discharge control module and used for judging whether the overcurrent is overtime or not by comparing the time when the overcurrent occurs with the preset delay time.
The battery discharged overcurrent protection circuit in, discharge control module includes battery protection chip, sampling resistor, comparator, current-limiting control switch tube, wherein, sampling resistor's first end connects respectively the negative pole and the ground of battery, sampling resistor's second end connects discharge switch tube's second end reaches the first input of comparator, discharge switch tube's first end connects the negative pole of discharge port, the second input termination reference voltage of comparator, the output termination of comparator current-limiting control switch tube's control end, current-limiting control switch tube's second end ground connection, current-limiting control switch tube's first end connects respectively discharge switch tube's control end with battery protection chip's discharge control end.
In the battery discharging overcurrent protection circuit of the present invention, the discharge control module comprises a battery protection chip, a sampling resistor, a comparator, an amplifier, and a current-limiting control switch tube, wherein a first end of the sampling resistor is connected to the positive electrode of the battery and a first input end of the amplifier, a second end of the sampling resistor is connected to the positive electrode of the discharge port and a second input end of the amplifier, an output end of the amplifier is connected to the first input end of the comparator, a second input end of the comparator is connected to a reference voltage, an output end of the comparator is connected to a control end of the current-limiting control switch tube, a second end of the current-limiting control switch tube is grounded, a first end of the current-limiting control switch tube is connected to the control end of the discharge switch tube and the discharge control end of the battery protection chip, and a first end of the discharge switch tube is connected to the negative electrode of the discharge port, and the second end of the discharge switching tube is respectively connected with the cathode of the battery and the ground.
The battery discharge's overcurrent protection circuit in, discharge control module still includes current-limiting resistor, current-limiting resistor's first end is connected battery protection chip's the control end that discharges, current-limiting resistor's second end is connected discharge switch's control end with current-limiting control switch's first end.
In the battery discharging overcurrent protection circuit of the present invention, the delay module includes a first diode, a first switch tube, a second switch tube, a first capacitor, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein a first end of the first switch tube is connected to the voltage sampling end of the battery protection chip, a second end of the first switch tube and a second end of the second switch tube are respectively grounded, and a control end of the first switch tube and a first end of the second switch tube are connected to the negative electrode of the discharge port through the first resistor; the positive pole of the first diode is connected with the negative pole of the discharge port, the negative pole of the first diode is connected with the first end of the first capacitor and the control end of the second switch tube through the second resistor, the second end of the first capacitor is grounded, the negative pole of the discharge port is connected with the voltage sampling end of the battery protection chip through the third resistor, and the fourth resistor is connected between the negative pole of the first diode and the ground.
In the overcurrent protection circuit for battery discharge of the present invention, the discharge control module comprises a battery protection chip, a sampling resistor, a current-limiting control switch tube, a fifth resistor, a sixth resistor, a second capacitor and a second diode, wherein a first end of the sampling resistor is connected to the negative electrode and the ground of the battery, a second end of the sampling resistor is connected to the second end of the discharge switch tube and the second end of the current-limiting control switch tube, a first end of the discharge switch tube is connected to the negative electrode of the discharge port, a control end of the discharge switch tube is connected to the positive electrode of the second diode, a negative electrode of the second diode is connected to the discharge control end of the battery protection chip, the sixth resistor is connected between the positive electrode and the negative electrode of the second diode, and a first end of the current-limiting control switch tube is connected to the voltage sampling end of the battery protection chip, the first end of the fifth resistor is connected with the discharge control end of the battery protection chip, the second end of the fifth resistor is respectively connected with the control end of the current-limiting control switch tube and the first end of the second capacitor, and the second end of the second capacitor is grounded.
In the overcurrent protection circuit for battery discharge, the delay module includes first diode, second resistor, third resistor, fourth resistor, first electric capacity and second switch tube, wherein, the positive pole of first diode is connected the negative pole of discharge port, the negative pole of first diode passes through second resistor connects the first end of first electric capacity reaches the control end of second switch tube, the second end of first electric capacity reaches the second end ground connection of second switch tube, the first end of second switch tube is connected the control end of current-limiting control switch tube, the negative pole of discharge port still passes through the third resistor connects the voltage sampling end of battery protection chip, the fourth resistor is connected between the negative pole of first diode and ground.
In the overcurrent protection circuit for battery discharge, the discharge control module further includes a third diode and a seventh resistor, wherein the negative electrode of the third diode is connected to the control end of the current-limiting control switch tube, the positive electrode of the third diode is connected to the negative electrode of the discharge port through the seventh resistor.
By implementing the technical scheme of the utility model, after the load is connected into the battery, the discharge current is detected in real time, whether overcurrent occurs or not is judged, and if no overcurrent occurs, the discharge switch tube is controlled to be switched on; if the overcurrent occurs, the discharge switch tube is controlled to be switched off, meanwhile, whether the overcurrent is overtime or not is judged by comparing the time of the overcurrent with the preset delay time, and if the overcurrent is overtime, the discharge switch tube is locked in a switched-off state. Therefore, when overcurrent occurs, if the overcurrent does not time out, the discharge switch tube works in a discontinuous opening mode during the overcurrent occurrence period, and when the overcurrent is finished, the discharge switch tube is continuously opened; if the time is out, the discharge switch tube works in a discontinuous on mode within the delay time, and the discharge switch tube is locked in an off state after the delay time is over. Therefore, when the battery charges the capacitive load, the battery is not charged fully at one time, but is accumulated after being charged for multiple times, so that the transient current of battery discharge can be reduced, the discharge energy of the battery is effectively limited, and the safety of the battery is improved.
Drawings
The invention will be further explained with reference to the drawings and examples, wherein:
fig. 1 is a logic diagram of a first embodiment of the overcurrent protection circuit for battery discharge according to the present invention;
FIG. 2 is a timing diagram of the discharge current and discharge switch tube states and the loading time, respectively, of FIG. 1;
fig. 3 is a circuit diagram of a second embodiment of the over-current protection circuit for battery discharge of the present invention;
fig. 4 is a circuit diagram of a third embodiment of the over-current protection circuit for battery discharge of the present invention;
fig. 5 is a circuit diagram of a fourth embodiment of the over-current protection circuit for battery discharge of the present invention;
fig. 6 is a flowchart of a first embodiment of the over-current protection method for battery discharging according to the present invention.
Detailed Description
Fig. 1 is a logic diagram of a first embodiment of the battery discharging overcurrent protection circuit of the present invention, the battery discharging overcurrent protection circuit includes a discharge switch tube (not shown), a discharge control module 10 and a delay module 20, wherein the discharge switch tube is connected to a battery discharge path, the discharge control module 10 is configured to detect a discharge current of a battery in real time, and determine whether an overcurrent occurs by comparing the detected discharge current with a preset threshold, and if no overcurrent occurs, control the discharge switch tube to open; and if the overcurrent occurs, the discharge switch tube is controlled to be switched off, and the discharge switch tube is locked in a switched-off state when the overcurrent exceeds the time. The delay module 20 is configured to compare the time when the overcurrent occurs with a preset delay time to determine whether the overcurrent is over time.
Referring to fig. 2, when a load is connected to a battery, a discharge current i of the battery starts to be detecteddThereby judging whether overcurrent occurs, i.e. whether the overcurrent exceeds a threshold value i of the currentr. If no overcurrent occurs, the discharge switch tube is controlled to be switched on; if the overcurrent occurs, the discharge switch tube is controlled to be switched off, meanwhile, whether the overcurrent is overtime or not is judged by comparing the time of the overcurrent with the preset delay time, and if the overcurrent is overtime, the discharge switch tube is locked in a switched-off state. For example, if at t1At the moment, overcurrent occurs2The moment overcurrent ends, and the overcurrent has no overtime, i.e. the time (t) of overcurrent2-t1Time period) does not exceed the delay time, the discharge control module 10 controls the discharge switch tube to operate in a discontinuous on mode during the discharge overcurrent period, and controls the discharge switch tube to be continuously on after the discharge overcurrent is finished. It should be noted that the response time t should be considered when controlling the operation of the discharge switch tube0。
As another example, if the battery is discharged at t3An overcurrent occurs at a time t4The moment of time overcurrent has not yet ended, i.e. the time (t) at which overcurrent occurs4-t3Time period of) reaching the delay time tdAt the delay time tdIn the interior, the discharge control module 10 controls the discharge switch tube to operate in discontinuous conduction mode and at the end of the delay time, i.e. at t4And after the moment, the discharge switch tube is locked in an off state.
According to the technical scheme of the embodiment, after the load is connected to the battery, when overcurrent occurs, if the overcurrent is not overtime, the discharge switch tube works in a discontinuous opening mode during the overcurrent occurrence period, and when the overcurrent is ended, the discharge switch tube is continuously opened; if the time is out, the discharge switch tube works in a discontinuous on mode within the delay time, and the discharge switch tube is locked in an off state after the delay time is over. Therefore, when the battery charges the capacitive load, the battery is not fully charged at one time, but is accumulated after being charged for multiple times, so that the discharge transient current of the battery can be reduced, the discharge transient energy of the battery is effectively limited, and the safety of the battery is improved.
Fig. 3 is a circuit diagram of the second embodiment of the over-current protection circuit for battery discharge of the present invention, the battery includes the electric core B1, B2 connected in series, the positive electrode of the electric core B1 is the positive electrode of the battery, the negative electrode of the electric core B2 is the negative electrode of the battery, and the negative electrode of the battery is grounded. The battery discharging overcurrent protection circuit comprises a discharging switch tube, a discharging control module and a time delay module. In addition, the battery is a rechargeable battery, and the overcurrent protection circuit further comprises a charging switch tube. In this embodiment, the discharge switch is a MOS transistor Q2, and the charge switch is a MOS transistor Q1. Of course, if the battery can be a non-rechargeable battery in other embodiments, the charging switch tube can be omitted. The discharge control module and the delay module are specifically described below.
In the discharging control module, the battery protection chip U1 may be a chip with model S8232, and regarding each port of the battery protection chip U1, DO is a discharging control terminal for controlling the MOS transistor Q2. And the CO is a charging control terminal and is used for controlling the MOS transistor Q1. ICT is the timing capacitor link, and this timing capacitor is electric capacity C4, changes the adjustable charge-discharge detection response time of electric capacity C4. VM is a voltage sampling terminal, the input voltage of the port is compared with a reference voltage (for example, 0.3V) set inside the port, and the comparison result is used for threshold control of the current. VC and SENS are cell voltage detection ends of the battery, wherein VC is connected with the anode of a cell B2 through a resistor R3, and SENS is connected with the anode of a cell B1 through a resistor R1. VCC is an IC internal line power supply terminal, and is connected to the positive electrode of the battery cell B1 through a resistor R2. In addition, the terminals VCC, VC and SENS are grounded through capacitors C2, C3 and C1, which serve as voltage stabilizing and filtering functions and can be omitted in other embodiments.
When the battery protection chip U1 works normally, namely no discharging overcurrent or no charging overcurrent occurs, the discharging control end (DO) and the charging control end (CO) of the battery protection chip U1 both output high voltage to control the conduction of the MOS tube Q1 and the MOS tube Q2, so that a charging path or a discharging path is formed. During discharging, if the cell voltage is lower than the discharging voltage threshold or the discharging current exceeds the current threshold, the discharging control end (DO) of the battery protection chip U1 outputs a low voltage to control the MOS transistor Q2 to turn off, and the battery stops discharging. During charging, if the cell voltage exceeds the charging voltage threshold, the charging control terminal (CO) of the battery protection chip U1 outputs a low voltage to control the MOS transistor Q1 to turn off, and the charging of the battery is stopped.
IN the discharging control module, a first end of a sampling resistor R4 is connected with a cathode of the battery cell B2, a second end of the sampling resistor R4 is connected with a source of the MOS tube Q2, a second end of the sampling resistor R4 is further connected with a first input end (IN +) of the comparator U2 through a resistor R10, a second input end (IN-) of the comparator U2 is connected with the reference voltage Verf, a drain of the MOS tube Q2 is connected with a drain of the MOS tube Q1, a source of the MOS tube Q1 is connected with a cathode P of the discharging port, a gate of the MOS tube Q2 is connected with a discharging control end (DO) of the battery protection chip U1 through a resistor R6, and a gate of the MOS tube Q1 is connected with a charging control end (CO) of the battery protection chip U1. The output end of the comparator U2 is connected with the grid of the MOS tube Q3, the source electrode of the MOS tube Q3 is grounded, and the drain electrode of the MOS tube Q3 is connected with the grid of the MOS tube Q2. IN addition, a capacitor C7 is connected between the second input terminal (IN-) of the comparator U2 and the ground, the power supply terminal (VCC) of the comparator U2 is connected to the positive electrode of the cell B1, and a capacitor C5 is connected between the power supply terminal (VCC) of the comparator U2 and the ground. It should be noted that the reference voltage of the comparator U2 can be provided by a voltage regulator chip, and can also be provided by other reference voltage sources. In addition, the capacitors C3, C2, C1, C7 and C5 play a role of voltage stabilization and filtering in this embodiment, and the resistors R10 and R6 play a role of current limiting, and these capacitors and resistors can be omitted in other embodiments.
In the delay module, the source of the MOS transistor Q5 is connected to the voltage sampling terminal (VM) of the battery protection chip U1, the drain of the MOS transistor Q5 is connected to the drain of the MOS transistor Q4, the source of the MOS transistor Q4 and the source of the MOS transistor Q6 are grounded, respectively, the gate of the MOS transistor Q5, the gate of the MOS transistor Q4 and the drain of the MOS transistor Q6 are connected together, and are connected to the negative P-of the discharge port through the resistor R7. The anode of the diode D1 is connected to the cathode P-of the discharge port, the cathode of the diode D1 is connected to the first end of the capacitor C6 and the gate of the MOS transistor Q6 through the resistor R8, the second end of the capacitor C6 is grounded, and the cathode P-of the discharge port is further connected to the voltage sampling end (VM) of the battery protection chip U1 through the resistor R5. In addition, a resistor R9 is connected between the cathode of the diode D1 and the ground, and the resistor R9 provides a discharge path for the C6. In this embodiment, the MOS transistors Q4 and Q5 are connected in parallel with each other in reverse, and therefore, the series connection of the MOS transistors Q4 and Q5 is selected to prevent bidirectional conduction. If MOS tubes without anti-parallel diodes are selected, one MOS tube can be used to replace the MOS tubes Q4 and Q5 which are connected in series.
The operation of the overcurrent protection circuit for battery discharge of this embodiment is explained below: when the load is connected to the discharge port, the charging control terminal (CO) and the discharging control terminal (DO) of the battery protection chip U1 both output high levels, and the MOS transistors Q1 and Q2 are turned on. If the battery cell is in a normal state, namely when no discharging overcurrent occurs, the voltage on the sampling resistor R4 is lower than the reference voltage of the comparator U2, the output end (OUT) of the comparator U2 outputs a low level, the MOS tube Q3 is turned off, the MOS tube Q2 is turned on because the grid voltage of the MOS tube Q2 is pulled up by the high voltage of the discharging control end (DO) of the battery protection chip U1, and at the moment, the output voltage of the battery cell forms a discharging path through the discharging port and the MOS tubes Q1 and Q2.
When discharge overcurrent occurs, the voltage on the sampling resistor R4 is greater than the reference voltage of the comparator U2, the output end (OUT) of the comparator U2 outputs high level, the MOS tube Q3 is turned on, the MOS tube Q2 is turned off because the gate voltage of the MOS tube Q3 is pulled low, and the discharge path is disconnected. When the MOS transistor Q2 is turned off, the voltage across the sampling resistor R4 drops, and when the voltage is lower than the reference voltage of the comparator U2, the comparator U2 outputs a low level again, the MOS transistor Q3 is turned off again, the MOS transistor Q2 is turned on because the gate voltage of the MOS transistor Q2 is pulled high by the high voltage of the discharge control terminal (DO) of the battery protection chip U1, and the discharge path is turned on again. Thus, the MOS transistor Q2 operates in the discontinuous on state.
In addition, during the period that the MOS tube Q2 is turned off after the battery is discharged and overcurrent, the voltage of the negative pole P-of the discharge port is raised, and the voltage controls the MOS tubes Q4 and Q5 to be turned on through the resistor R7, so that the voltage sampling end (VM) of the battery protection chip U1 is grounded. Meanwhile, the high voltage of the cathode P-of the discharge port charges the capacitor C6 through the diode D1 and the resistor R8. Since the MOS transistor Q2 is turned off intermittently during overcurrent, the charging of the capacitor C6 is accumulated several times.
As the voltage of the capacitor C6 increases, the MOS transistor Q2 operates in the off state until the turn-on threshold voltage of the MOS transistor Q6 is reached. If the voltage of the capacitor C6 reaches the turn-on threshold voltage of the MOS transistor Q6, the MOS transistor Q6 is turned on, the MOS transistors Q4 and Q5 are turned off due to the gate voltages thereof being pulled low, and at the same time, the resistor R5 couples the high voltage of the negative pole P-of the discharge port to the voltage sampling terminal (VM) of the battery protection chip U1, and when the voltage is greater than the internal reference voltage (0.3V), the discharge control terminal (DO) of the battery protection chip U1 outputs a low level, the MOS transistor Q2 is turned off due to the loss of the gate voltage, and thereafter, the voltage of the negative pole P-of the discharge port is always applied to the voltage sampling terminal (VM) of the battery protection chip U1 through the resistor R5, so that the discharge control terminal (DO) of the battery protection chip U1 continuously outputs a low voltage, the MOS transistor Q2 is locked in the off state, and the discharge path of the battery is locked in.
In addition, before the charging voltage of the capacitor C6 reaches the gate threshold voltage of the MOS transistor Q6, since the MOS transistors Q4 and Q5 are in the on state, the high voltage of the negative electrode P-of the discharge port cannot be applied to the voltage sampling terminal (VM) of the battery protection chip U1, the discharge control terminal (DO) of the battery protection chip U1 is always at the high voltage, the MOS transistor Q2 is always operated in the intermittent on state due to the control of the MOS transistor Q3, the overcurrent waveform is a continuous pulse train, and the first pulse is higher than the following pulse amplitude.
After the MOS transistor Q2 is locked in the off state, only when the load connected to the discharge port is removed, the voltage of the negative electrode P-of the discharge port is lowered, and if the voltage of the voltage sampling terminal (VM) of the battery protection chip U1 is lowered to be lower than the internal reference voltage (0.3V), the discharge control terminal (DO) of the battery protection chip U1 outputs a high voltage, the MOS transistor Q2 is turned on again because the gate thereof obtains the high voltage, and the discharge path is turned back on. In addition, the resistor R6 is connected in series with the grid of the MOS transistor Q2, so that the turn-on speed of the MOS transistor Q2 can be reduced, and the transient peak current of battery discharge can be further reduced.
Fig. 4 is a circuit diagram of a third embodiment of the overcurrent protection circuit for battery discharge according to the present invention, and compared with the embodiment shown in fig. 3, the embodiment has the same circuit structure of the delay module, and the difference is only in the discharge control module. Only the circuit configuration of the discharge control module of this embodiment will be described below, in which the operational amplifier U2 is a chip of type AD8566, which includes two parts, the first part serving as an amplifier for amplifying the sampled voltage across the sampling resistor R4, and the second part serving as a comparator for comparing the sampled voltage with a reference voltage. Of course, in other embodiments, separate amplifiers and comparators may be used. In addition, in this embodiment, the sampling resistor R4 is connected between the positive electrode P + of the discharge port and the positive electrode of the battery B1, the first end of the sampling resistor R4 is connected to the first INPUT terminal (B-INPUT) of the first portion of the operational amplifier U2 through the resistor R10, the second end of the sampling resistor R4 is connected to the second INPUT terminal (B + INPUT) of the first portion of the operational amplifier U2 through the resistor R22, the resistor R23 is connected between the second INPUT terminal (B + INPUT) of the first portion of the operational amplifier U2 and ground, the OUTPUT terminal (B OUTPUT) of the first portion of the operational amplifier U2 is connected to the first INPUT terminal (a + INPUT) of the second portion of the operational amplifier U2, the second INPUT terminal (a-INPUT) of the second portion of the operational amplifier U2 is connected to the reference voltage Verf, the OUTPUT terminal (a-INPUT) of the second portion of the operational amplifier U6345 is connected to the source terminal of the MOS 85q 25, the source terminal 3 of the MOS transistor Q3, the drain of MOS transistor Q3 is connected to the gate of MOS transistor Q2, the drain of MOS transistor Q2 is connected to the drain of MOS transistor Q1, the source of MOS transistor Q1 is connected to the negative P-of the discharge port, the gate of MOS transistor Q2 is connected to the discharge control terminal (DO) of battery protection chip U1 through resistor R6, and the gate of MOS transistor Q1 is connected to the charge control terminal (CO) of battery protection chip U1. In addition, a capacitor C7 is connected between the second INPUT end (a-INPUT) of the second part of the operational amplifier U2 and the ground, a power supply end (V +) of the operational amplifier U2 is connected to the positive electrode of the battery B1, and a capacitor C5 is connected between the power supply end (V +) of the operational amplifier U2 and the ground.
The working process of the battery discharging overcurrent protection circuit of the embodiment is substantially the same as that of the second embodiment shown in fig. 3, except that the sampling resistor R4 is connected to the positive electrode of the discharge port, and an amplifier is used to obtain the voltage across the sampling resistor R4, so that the interference resistance can be improved. The specific reason is as follows: if the sampling resistor is arranged at the cathode of the discharge port, the cathode of the discharge port is generally directly connected with the grounding shell of the host machine, so that the anti-interference capability is relatively poor.
Fig. 5 is a circuit diagram of a fourth embodiment of the overcurrent protection circuit for battery discharge according to the present invention, and the structures of the discharge control module and the delay module of this embodiment are specifically described below.
In the discharge control module, a first end of a sampling resistor R4 is connected with a negative electrode of a battery cell B2, a second end of the sampling resistor R4 is connected with a source electrode of a MOS tube Q2, a second end of the sampling resistor R4 is also connected with a source electrode of a MOS tube Q3, a drain electrode of the MOS tube Q2 is connected with a drain electrode of the MOS tube Q1, a source electrode of the MOS tube Q1 is connected with a negative electrode P-of a discharge port, a gate electrode of the MOS tube Q1 is connected with a charge control end (CO) of a battery protection chip U1, a gate electrode of the MOS tube Q2 is connected with a positive electrode of a diode D2, a negative electrode of the diode D2 is connected with a discharge control end (DO) of the battery protection chip U1, a drain electrode of the MOS tube Q3 is connected with a voltage sampling end (CO) of the battery protection chip U1 through a resistor R13, a first end of the resistor R11 is connected with a discharge control end (DO) of the battery protection chip U1, and a second end of the resistor R. In addition, the resistor R6 is connected between the discharge control terminal (DO) of the battery protection chip U1 and the gate of the MOS transistor Q2 to reduce the on-speed of the Q2 to reduce the transient current of the battery discharge. The anode of the diode D3 is grounded through a resistor R14, and the cathode of the diode D3 is connected to the gate of the MOS transistor Q3.
In the delay module, the anode of the diode D1 is connected to the cathode P of the discharge port, the cathode of the diode D1 is connected to the first end of the capacitor C6 and the gate of the MOS transistor Q6 through the resistor R8, the second end of the capacitor C6 and the source of the MOS transistor Q6 are grounded, the drain of the MOS transistor Q6 is connected to the gate of the MOS transistor Q3, the cathode P of the discharge port is also connected to the voltage sampling end (VM) of the battery protection chip U1 through the resistor R5, and the resistor R9 is connected between the cathode of the diode D1 and the ground to provide a discharge path for the C6.
The operation of the overcurrent protection circuit for battery discharge of this embodiment is explained below: when the load is connected to the discharge port, the charging control terminal (CO) and the discharging control terminal (DO) of the battery protection chip U1 both output high levels, and the MOS transistors Q1 and Q2 are turned on. At this time, the output voltage of the battery cell forms a discharge path through the discharge port and the MOS transistors Q1, Q2. If the battery protection chip U1 is in a normal state, that is, no discharge overcurrent occurs, when the discharge control terminal (DO) of the battery protection chip U1 outputs a high voltage, the capacitor C7 is charged through the resistor R11, so that the voltage of the capacitor C7 is higher than the gate-on voltage of the MOS transistor Q3, the MOS transistor Q3 is turned on, the voltage across the sampling resistor R4 is coupled to the voltage sampling terminal (VM) of the battery protection chip U1 through the MOS transistor Q3 and the resistor R13, and if the voltage is lower than the internal reference voltage (0.3V) of the battery protection chip U1, the discharge control terminal (DO) of the battery protection chip U1 continuously outputs a high level to maintain a discharge path.
When overcurrent occurs, the voltage on the sampling resistor R4 is higher than the internal reference voltage (0.3V) of the battery protection chip U1, the discharge control end (DO) of the battery protection chip U1 outputs low level, the MOS tube Q2 is turned off, and the discharge path is disconnected. When the MOS transistor Q2 is turned off, the voltage across the sampling resistor R4 drops, and when the voltage is again lower than the reference voltage (0.3V) inside the battery protection chip U1, the discharge control terminal (DO) of the battery protection chip U1 outputs a high level, the MOS transistor Q2 is turned on, and the discharge path is turned on again. Thus, the MOS transistor Q2 operates in the discontinuous on state. It should be noted that, during the off period of the MOS transistor Q2, the voltage of the capacitor C7 does not suddenly decrease, and therefore, the MOS transistor Q3 is continuously turned on. In order to further ensure that the voltage of the capacitor C7 is higher than the gate-on voltage of the MOS transistor Q3 during the off period of the MOS transistor Q2, the high voltage of the negative electrode P-of the discharge port may also be used to charge the capacitor C7 through the resistor R14 and the diode D3.
In addition, during the turn-off of the MOS transistor Q2, the voltage of the negative pole P-of the discharge port is raised, and the voltage charges the capacitor C6 through the diode D1 and the resistor R8. Since the MOS transistor Q2 is turned off intermittently during overcurrent, the charging of the capacitor C6 is accumulated several times. As the voltage of the capacitor C6 increases, the MOS transistor Q2 operates in the off state until the turn-on threshold voltage of the MOS transistor Q6 is reached. If the on-threshold voltage of the MOS transistor Q6 is reached, the MOS transistor Q6 is turned on, the gate voltage of the MOS transistor Q3 is pulled low, meanwhile, the resistor R5 couples the high voltage of the negative pole P-of the discharge port to the voltage sampling terminal (VM) of the battery protection chip U1, when the voltage is greater than the internal reference voltage (0.3V), the discharge control terminal (DO) of the battery protection chip U1 outputs low level, the MOS transistor Q2 is turned off due to the loss of voltage at the gate thereof, and thereafter, the voltage of the negative pole P-of the discharge port is always applied to the voltage sampling terminal (VM) of the battery protection chip U1 through the resistor R5, so that the discharge control terminal (DO) of the battery protection chip U1 continuously outputs low voltage, the MOS transistor Q2 is locked in the off state, and the discharge path of the battery is locked in the off state.
Compared with the embodiment shown in fig. 3 and 4, the battery discharging overcurrent protection circuit of the embodiment can omit a comparator or an amplifier, and the delay module can save some switching tubes (such as MOS tubes Q4 and Q5), so the structure is simpler.
With respect to the several circuit diagrams shown above, it should be understood that these are only several embodiments of the present invention, and in other embodiments, the MOS transistor may be replaced by another type of switching transistor, some resistors for current limiting may be omitted, and some capacitors for voltage stabilizing and filtering may be omitted. Further, the current sensor may be used to convert the current of the positive electrode of the discharge port or the negative electrode of the discharge port into a voltage.
Fig. 6 is a flowchart of a first embodiment of the battery discharging overcurrent protection method of the present invention, where the battery discharging overcurrent protection method includes:
A. detecting the discharge current of the battery in real time, judging whether overcurrent occurs or not by comparing the detected discharge current with a preset threshold value, and if not, executing the step B; if yes, executing the step C;
B. controlling the discharge switch tube to be switched on, and then executing the step A;
C. controlling the discharge switch tube to be turned off, meanwhile, judging whether the overcurrent is overtime or not by comparing the time when the overcurrent occurs with the preset delay time, and if so, executing the step D; if not, executing the step A;
D. and locking the discharge switch tube in an off state, and then finishing.
In step C, whether the overcurrent is over time can be determined by the following method:
when the discharge switch tube is turned off, the high voltage charges the first capacitor through the second resistor, and whether the time is out is judged by judging the voltage of the first capacitor, wherein the preset delay time is related to the resistance value of the second resistor and the capacitance value of the first capacitor.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (6)
1. An overcurrent protection circuit for battery discharge comprises a discharge switch tube connected in a battery discharge path, and is characterized by further comprising a discharge control module and a time delay module connected to the discharge control module; wherein,
the discharging control module comprises a battery protection chip, a sampling resistor, a comparator and a current-limiting control switch tube, wherein the first end of the sampling resistor is respectively connected with the cathode of the battery and the ground, the second end of the sampling resistor is connected with the second end of the discharging switch tube and the first input end of the comparator, the first end of the discharging switch tube is connected with the cathode of a discharging port, the second input end of the comparator is connected with a reference voltage, the output end of the comparator is connected with the control end of the current-limiting control switch tube, the second end of the current-limiting control switch tube is grounded, and the first end of the current-limiting control switch tube is respectively connected with the control end of the discharging switch tube and the discharging control end of the battery protection chip;
the delay module comprises a first diode, a first switch tube, a second switch tube, a first capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein the first end of the first switch tube is connected with the voltage sampling end of the battery protection chip, the second end of the first switch tube and the second end of the second switch tube are respectively grounded, and the control end of the first switch tube and the first end of the second switch tube are connected with the negative electrode of the discharge port through the first resistor; the positive pole of the first diode is connected with the negative pole of the discharge port, the negative pole of the first diode is connected with the first end of the first capacitor and the control end of the second switch tube through the second resistor, the second end of the first capacitor is grounded, the negative pole of the discharge port is connected with the voltage sampling end of the battery protection chip through the third resistor, and the fourth resistor is connected between the negative pole of the first diode and the ground.
2. The battery discharging overcurrent protection circuit of claim 1, wherein the discharge control module further comprises a current-limiting resistor, a first end of the current-limiting resistor is connected to the discharge control end of the battery protection chip, and a second end of the current-limiting resistor is connected to the control end of the discharge switch tube and the first end of the current-limiting control switch tube.
3. An overcurrent protection circuit for battery discharge comprises a discharge switch tube connected in a battery discharge path, and is characterized by further comprising a discharge control module and a time delay module connected to the discharge control module; wherein,
the discharging control module comprises a battery protection chip, a sampling resistor, a comparator, an amplifier and a current-limiting control switch tube, wherein, the first end of the sampling resistor is respectively connected with the anode of the battery and the first input end of the amplifier, the second end of the sampling resistor is respectively connected with the anode of the discharge port and the second input end of the amplifier, the output end of the amplifier is connected with the first input end of the comparator, the second input end of the comparator is connected with a reference voltage, the output end of the comparator is connected with the control end of the current-limiting control switch tube, the second end of the current-limiting control switch tube is grounded, the first end of the current-limiting control switch tube is respectively connected with the control end of the discharge switch tube and the discharge control end of the battery protection chip, the first end of the discharge switch tube is connected with the negative electrode of the discharge port, and the second end of the discharge switch tube is respectively connected with the negative electrode of the battery and the ground;
the delay module comprises a first diode, a first switch tube, a second switch tube, a first capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein the first end of the first switch tube is connected with the voltage sampling end of the battery protection chip, the second end of the first switch tube and the second end of the second switch tube are respectively grounded, and the control end of the first switch tube and the first end of the second switch tube are connected with the negative electrode of the discharge port through the first resistor; the positive pole of the first diode is connected with the negative pole of the discharge port, the negative pole of the first diode is connected with the first end of the first capacitor and the control end of the second switch tube through the second resistor, the second end of the first capacitor is grounded, the negative pole of the discharge port is connected with the voltage sampling end of the battery protection chip through the third resistor, and the fourth resistor is connected between the negative pole of the first diode and the ground.
4. The battery discharging overcurrent protection circuit of claim 3, wherein the discharge control module further comprises a current-limiting resistor, a first end of the current-limiting resistor is connected to the discharge control end of the battery protection chip, and a second end of the current-limiting resistor is connected to the control end of the discharge switch tube and the first end of the current-limiting control switch tube.
5. An overcurrent protection circuit for battery discharge comprises a discharge switch tube connected in a battery discharge path, and is characterized by further comprising a discharge control module and a time delay module connected to the discharge control module; wherein,
the discharging control module comprises a battery protection chip, a sampling resistor, a current-limiting control switch tube, a fifth resistor, a sixth resistor, a second capacitor and a second diode, wherein the first end of the sampling resistor is respectively connected with the negative pole and the ground of the battery, the second end of the sampling resistor is respectively connected with the second end of the discharging switch tube and the second end of the current-limiting control switch tube, the first end of the discharging switch tube is connected with the negative pole of a discharging port, the control end of the discharging switch tube is connected with the positive pole of the second diode, the negative pole of the second diode is connected with the discharging control end of the battery protection chip, the sixth resistor is connected between the positive pole and the negative pole of the second diode, the first end of the current-limiting control switch tube is connected with the voltage sampling end of the battery protection chip, the first end of the fifth resistor is connected with the discharging control end of the battery protection chip, a second end of the fifth resistor is respectively connected with a control end of the current-limiting control switch tube and a first end of the second capacitor, and a second end of the second capacitor is grounded;
the time delay module comprises a first diode, a second resistor, a third resistor, a fourth resistor, a first capacitor and a second switch tube, wherein the anode of the first diode is connected with the cathode of the discharge port, the cathode of the first diode is connected with the first end of the first capacitor and the control end of the second switch tube through the second resistor, the second end of the first capacitor and the second end of the second switch tube are grounded, the first end of the second switch tube is connected with the control end of the current-limiting control switch tube, the cathode of the discharge port is connected with the voltage sampling end of the battery protection chip through the third resistor, and the fourth resistor is connected between the cathode of the first diode and the ground.
6. The battery discharging overcurrent protection circuit of claim 5, wherein the discharge control module further comprises a third diode and a seventh resistor, wherein a cathode of the third diode is connected to the control terminal of the current-limiting control switching tube, and an anode of the third diode is connected to a cathode of the discharge port through the seventh resistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320828682.6U CN203839985U (en) | 2013-12-13 | 2013-12-13 | Cell discharge overcurrent protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320828682.6U CN203839985U (en) | 2013-12-13 | 2013-12-13 | Cell discharge overcurrent protection circuit |
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| CN203839985U true CN203839985U (en) | 2014-09-17 |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103647323A (en) * | 2013-12-13 | 2014-03-19 | 海能达通信股份有限公司 | Cell discharge overcurrent protection circuit and cell discharge overcurrent protection method |
| CN104795807A (en) * | 2015-04-16 | 2015-07-22 | 上海空间电源研究所 | High-reliability current protecting circuit for astronavigation |
| CN105203962A (en) * | 2015-08-31 | 2015-12-30 | 北汽福田汽车股份有限公司 | Vehicle-mounted battery over-current diagnostic method and device |
| US10090689B2 (en) | 2013-12-13 | 2018-10-02 | Hytera Communications Corp., Ltd. | Overcurrent protection circuit and method for limiting discharge current of battery within safety limiting value |
| CN111864819A (en) * | 2019-04-30 | 2020-10-30 | 松下电气机器（北京）有限公司 | Control device and method for storage battery |
| CN114139224A (en) * | 2021-11-20 | 2022-03-04 | 苏州浪潮智能科技有限公司 | Protection device of server and server |
| CN115172912A (en) * | 2022-09-07 | 2022-10-11 | 禹创半导体(深圳)有限公司 | Method for prolonging standby time of battery by battery protection chip |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103647323A (en) * | 2013-12-13 | 2014-03-19 | 海能达通信股份有限公司 | Cell discharge overcurrent protection circuit and cell discharge overcurrent protection method |
| US10090689B2 (en) | 2013-12-13 | 2018-10-02 | Hytera Communications Corp., Ltd. | Overcurrent protection circuit and method for limiting discharge current of battery within safety limiting value |
| CN104795807A (en) * | 2015-04-16 | 2015-07-22 | 上海空间电源研究所 | High-reliability current protecting circuit for astronavigation |
| CN104795807B (en) * | 2015-04-16 | 2018-02-06 | 上海空间电源研究所 | A kind of aerospace high reliability current protecting circuit |
| CN105203962A (en) * | 2015-08-31 | 2015-12-30 | 北汽福田汽车股份有限公司 | Vehicle-mounted battery over-current diagnostic method and device |
| CN111864819A (en) * | 2019-04-30 | 2020-10-30 | 松下电气机器（北京）有限公司 | Control device and method for storage battery |
| CN114139224A (en) * | 2021-11-20 | 2022-03-04 | 苏州浪潮智能科技有限公司 | Protection device of server and server |
| CN114139224B (en) * | 2021-11-20 | 2023-11-21 | 苏州浪潮智能科技有限公司 | Protection device of server and server |
| CN115172912A (en) * | 2022-09-07 | 2022-10-11 | 禹创半导体(深圳)有限公司 | Method for prolonging standby time of battery by battery protection chip |
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