CN114336885B

CN114336885B - Overvoltage and overcurrent charging protection device and lead-acid battery charging circuit

Info

Publication number: CN114336885B
Application number: CN202210017073.6A
Authority: CN
Inventors: 张玉良; 郑冬冬; 付照德; 杨俊鹏
Original assignee: Henan Muyuan Intelligent Technology Co Ltd
Current assignee: Henan Muyuan Intelligent Technology Co Ltd
Priority date: 2022-01-07
Filing date: 2022-01-07
Publication date: 2024-05-14
Anticipated expiration: 2042-01-07
Also published as: CN114336885A

Abstract

The invention discloses an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit, wherein a control module in the device charges when a first controllable switch module is turned off and the output end of a charging power supply is not overvoltage or overcurrent, and controls the first controllable switch module to be turned on after the charging is finished, so that the delay charging of the charging power supply to a battery is realized; discharging is performed when the first controllable switch module is conducted and the output end of the charging power supply is over-voltage and/or over-current, and the first controllable switch module is controlled to be turned off after discharging is finished, so that the delay power-off of the charging power supply to the battery is realized. According to the scheme, the situation that the output voltage of the charging power supply fluctuates at a critical point, the output voltage of the charging power supply fluctuates greatly due to the damage of the charging power supply and the output current of the charging power supply flows excessively is avoided through the delay processing on the premise of ensuring the charge protection of the battery, and the practicability and the stability of the overvoltage and overcurrent charging protection device are enhanced.

Description

Overvoltage and overcurrent charging protection device and lead-acid battery charging circuit

Technical Field

The invention relates to the field of circuit protection, in particular to an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit.

Background

Lead acid batteries currently occupy a considerable portion of the market as a low cost and high safety battery. For charging of lead acid batteries, the following methods are generally used in the prior art: the method is characterized in that a charger or a direct current power supply is used for directly charging the lead-acid battery, however, the technical indexes of the charger and the direct current power supply are uneven, and if the charger or the direct current power supply is improperly selected or damaged in use, the lead-acid battery is easy to be subjected to long-time overvoltage or overcurrent charging due to the fact that a corresponding protection circuit is not arranged in the method, so that the service life of the lead-acid battery is seriously influenced.

The second mode is to add a charging protection circuit on the charging circuit of the lead-acid battery. Thus, referring to fig. 1, fig. 1 shows a charging circuit of a lead-acid battery in the prior art for the input voltage and input current of a charger or a dc power supply. In the charging circuit, the output voltage of the charger is sampled through two voltage dividing resistors and the sampling result is transmitted to a comparator A1, and the comparator A1 immediately controls a switching tube Q to be turned off when the output voltage of the charger is over-voltage so that the lead-acid battery cannot be charged; the output current of the charger is sampled through the sampling resistor and the sampling result is transmitted to the comparator A2, and the comparator A2 immediately controls the switch tube Q to be turned off when the output current of the charger flows, so that the lead-acid battery cannot be charged, and the protection of charging the lead-acid battery is completed. However, there are many problems in this way, one is that when the charging voltage fluctuates at the overvoltage critical point or the charger is damaged, the output voltage of the comparator A1 will immediately respond to control the switching tube Q to turn on and off, this frequent action causes frequent charging of the lead-acid battery, and when the output current is larger, the switching tube Q will generate larger switching loss, which is likely to be thermally broken down; secondly, when the output current of the charger flows, the comparator A2 immediately responds to control the switching tube Q to be turned on and off, and the frequent action also causes frequent charging of the lead-acid battery, and meanwhile, when the output current is larger, the switching tube Q generates larger switching loss and is likely to be thermally broken down.

Disclosure of Invention

The invention aims to provide an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit, which avoid frequent on and off of a first controllable switch module through delay treatment on the premise of ensuring the charging protection of a battery and enhance the practicability and the stability of the overvoltage and overcurrent charging protection device.

In order to solve the technical problems, the invention provides an overvoltage and overcurrent charging protection device, which comprises a voltage detection module, a current detection module, a sampling resistor, a control module and a first controllable switch module;

The charging power supply is connected with the battery to form a charging loop, the first controllable switch module and the sampling resistor are arranged on the charging loop, and the voltage detection module is respectively connected with the charging power supply and the control module; the current detection module is respectively connected with the sampling resistor and the control module;

The control module is also connected with the control end of the first controllable switch module and is used for charging when the first controllable switch module is turned off, the voltage detection module judges that the output end of the charging power supply is not over-voltage, the current detection module judges that the output end of the charging power supply is not over-current, and the first controllable switch module is controlled to be turned on after the charging is finished; the first controllable switch module is conducted, the voltage detection module judges that the output end of the charging power supply is over-voltage and/or the current detection module judges that the output end of the charging power supply is over-current, and discharges and controls the first controllable switch module to be turned off after the discharge is finished; and when the first controllable switch module is conducted, the voltage detection module judges that the output end of the charging power supply is not over-voltage, and the current detection module judges that the output end of the charging power supply is not over-current, the first controllable switch module is kept controlled to be conducted.

Preferably, the current detection module includes a first comparator;

The anode of the first comparator is connected with one end of the sampling resistor, the cathode of the first comparator is connected with the control module, the reference end of the first comparator is connected with the other end of the sampling resistor, and the first comparator is used for conducting when the output end of the charging power supply is judged to be over-current according to the voltage at the two ends of the sampling resistor, and is used for switching off when the output end of the charging power supply is judged to be not over-current according to the voltage at the two ends of the sampling resistor.

Preferably, the voltage detection module comprises a first resistor, a second resistor, a third resistor, a first zener diode and a second comparator;

One end of the first resistor is respectively connected with the positive electrode of the charging power supply, the positive electrode of the battery and one end of the third resistor, the other end of the first resistor is connected with one end of the second resistor, the connected common end of the first resistor is connected with the reference end of the second comparator, the other end of the second resistor is respectively connected with the negative electrode of the charging power supply, the anode of the second comparator, the anode of the first zener diode and one end of the sampling resistor, and the cathode of the second comparator is connected with the other end of the third resistor, and the connected common end of the second resistor is respectively connected with the cathode of the first zener diode and the control module;

the second comparator is used for being conducted when the voltage at two ends of the second resistor is used for judging that the output end of the charging power supply is overvoltage, and being turned off when the voltage at two ends of the second resistor is used for judging that the output end of the charging power supply is not overvoltage; the first voltage stabilizing diode is used for stabilizing voltage when the first comparator and the second comparator are both turned off, and is turned off when the second comparator and/or the first comparator are/is turned on.

Preferably, the voltage detection module further comprises a fourth resistor and a first controllable switch;

One end of the fourth resistor is connected with one end of the second resistor, and the other end of the fourth resistor is connected with the first end of the first controllable switch;

The second end of the first controllable switch is connected with the other end of the second resistor, and the control end of the first controllable switch is connected with the control end of the first controllable switch module and is used for being turned on when the first controllable switch module is turned on and turned off when the first controllable switch module is turned off;

the method comprises the steps of conducting when the voltage of the two ends of the second resistor is used for judging that the output end of the charging power supply is overvoltage, and conducting when the voltage of the two ends of the second resistor is used for judging that the output end of the charging power supply is not overvoltage, and comprising the following steps:

the power supply is turned on when the overvoltage of the output end of the charging power supply is judged according to the voltage of the two ends of the equivalent resistor after the second resistor and the fourth resistor are connected in parallel, and turned off when the overvoltage of the output end of the charging power supply is judged according to the voltage of the two ends of the second resistor.

Preferably, the voltage detection module further comprises a fifth resistor, a second zener diode, a third zener diode, an optocoupler, a second controllable switch and a sixth resistor;

one end of the fifth resistor is connected with one end of the first resistor and the cathode of the second zener diode respectively, and the other end of the fifth resistor is connected with the first end of the second controllable switch;

The light emitting diode of the optocoupler is connected between the other end of the third resistor and the cathode of the second comparator, the anode of the light emitting diode is respectively connected with the other end of the third resistor and the cathode of the first zener diode, the cathode of the light emitting diode is connected with the cathode of the second comparator, the collector of the phototriode of the optocoupler is connected with the anode of the third zener diode, the emitter of the phototriode is connected with one end of the sixth resistor, and the light emitting diode is used for being turned on when the second comparator is turned on, and is turned off when the second comparator is turned off; the phototriode is used for being switched on when the light emitting diode is switched on and being switched off when the light emitting diode is switched off;

the other end of the sixth resistor is connected with the anode of the second comparator; the second voltage stabilizing diode is used for stabilizing voltage; the third zener diode is used for stabilizing voltage;

The second end of the second controllable switch is respectively connected with the other end of the first resistor and the reference end of the second comparator, and the control end of the second controllable switch is respectively connected with the anode of the second zener diode and the cathode of the third zener diode and is used for being conducted when the phototriode is conducted and being turned off when the phototriode is turned off.

Preferably, the first controllable switch module comprises a third controllable switch and a fourth zener diode;

The control end of the third controllable switch is connected with the cathode of the fourth voltage stabilizing diode and the public end connected with the cathode of the fourth voltage stabilizing diode is used as the control end of the first controllable switch module, the first end of the third controllable switch is connected with the anode of the fourth voltage stabilizing diode and the public end connected with the anode of the fourth voltage stabilizing diode is connected with the other end of the sampling resistor, and the second end of the third controllable switch is connected with the cathode of the battery.

Preferably, the control module comprises a first diode, a capacitor, a fourth controllable switch, a seventh resistor, an eighth resistor, a fifth zener diode, a fifth controllable switch and a sixth controllable switch;

The cathode of the first diode is respectively connected with the cathode of the first zener diode, the cathode of the first comparator, the first end of the sixth controllable switch and one end of the seventh resistor, and the anode of the first diode is connected with the control end of the fourth controllable switch and is used for being turned on when the second comparator and/or the first comparator are turned on and turned off when the second comparator and the first comparator are turned off;

The other end of the seventh resistor is connected with one end of the capacitor, a public end connected with the other end of the seventh resistor is connected with the first end of the fourth controllable switch and the cathode of the fifth voltage stabilizing diode respectively, the other end of the capacitor is connected with the other end of the sampling resistor, one end of the eighth resistor and the second end of the fifth controllable switch respectively, and the capacitor is used for charging when the first controllable switch module is turned off, the first comparator is turned off, and the second comparator is turned off; discharging when the first controllable switch module is turned on and the first comparator is turned on and/or the second comparator is turned on;

the second end of the fourth controllable switch is connected with the other end of the eighth resistor and is used for being turned on when the first diode is turned on and turned off when the first diode is turned off;

The fifth zener diode is used for being turned on when the capacitor is charged, turned off when the capacitor is discharged, and kept on when the first controllable switch module is turned on, the first comparator is turned off, and the second comparator is turned off;

The control end of the fifth controllable switch is connected with the anode of the fifth zener diode, and the first end of the fifth controllable switch is connected with the control end of the sixth controllable switch and is used for being turned on when the fifth zener diode is turned on and turned off when the fifth zener diode is turned off;

the control end of the sixth controllable switch is connected with the control end of the first controllable switch module, and is used for being conducted when the fifth controllable switch is conducted to control the first controllable switch module to be conducted, and being turned off when the fifth controllable switch is turned off to control the first controllable switch module to be turned off.

Preferably, the circuit further comprises a ninth resistor, a tenth resistor, an eleventh resistor and a sixth zener diode;

one end of the ninth resistor is connected with the positive electrode of the charging power supply, the other end of the ninth resistor is connected with one end of the tenth resistor, a connected common end of the ninth resistor is connected with the cathode of the sixth zener diode, the other end of the tenth resistor is connected with one end of the eleventh resistor, the connected common end of the tenth resistor is connected with the reference end of the first comparator, the other end of the eleventh resistor is respectively connected with the other end of the sampling resistor and the anode of the sixth zener diode, and the zener diode is used for providing stable voltage;

The method for judging whether the output end of the charging power supply is over-current or not according to the voltage of the two ends of the sampling resistor comprises the steps of:

And the output end of the charging power supply is turned on when the overcurrent of the output end of the charging power supply is judged according to the sum of the voltages of the two ends of the sampling resistor and the voltage of the two ends of the eleventh resistor, and the output end of the charging power supply is turned off when the overcurrent of the output end of the charging power supply is judged according to the sum of the voltages of the two ends of the sampling resistor and the voltage of the two ends of the eleventh resistor.

Preferably, the circuit further comprises a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a third comparator;

The reference end of the third comparator is connected with the cathode of the third comparator, and the connected common end is respectively connected with one end of the twelfth resistor and one end of the thirteenth resistor for providing stable voltage;

The other end of the twelfth resistor is connected with the positive electrode of the charging power supply, the other end of the thirteenth resistor is connected with one end of the fourteenth resistor, the connected common end is connected with the reference end of the first comparator, and the other end of the fourteenth resistor is respectively connected with the other end of the sampling resistor and the anode of the third comparator;

And the output end of the charging power supply is turned on when the over-current is judged according to the sum of the voltages of the two ends of the sampling resistor and the voltage of the two ends of the fourteenth resistor, and the output end of the charging power supply is turned off when the over-current is not judged according to the sum of the voltages of the two ends of the sampling resistor and the voltage of the two ends of the fourteenth resistor.

In order to solve the technical problems, the invention also provides a lead-acid battery charging circuit which comprises a lead-acid battery, a charging power supply, and the overvoltage and overcurrent charging protection device, wherein the charging power supply, the overvoltage and overcurrent charging protection device and the lead-acid battery are connected in sequence.

The invention provides an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit, wherein the charging of a battery by a charging power supply can be realized when a first controllable switch module in the device is conducted, so that a control module in the device is used for charging when the first controllable switch module is turned off, a voltage detection module judges that the output end of the charging power supply is not overvoltage, and a current detection module judges that the output end of the charging power supply is not overcurrent, and the first controllable switch module is controlled to be conducted after the charging is finished, thereby realizing the delay charging of the battery by the charging power supply; when the first controllable switch module is conducted and the voltage detection module judges that the output end of the charging power supply is overvoltage and/or the current detection module judges that the output end of the charging power supply is overcurrent, discharging is carried out first, and the first controllable switch module is controlled to be turned off after discharging is finished, so that the delay power-off of the charging power supply to the battery is realized. Compared with the prior art, the scheme aims at three conditions of fluctuation of the output voltage of the charging power supply at a critical point, large fluctuation of the output voltage of the charging power supply caused by damage of the charging power supply and overcurrent of the output current of the charging power supply, and on the premise of ensuring the charge protection of a battery, frequent on and off of the first controllable switch module are avoided through the delay processing, and the practicability and the stability of the overvoltage overcurrent charging protection device are enhanced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the prior art and the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a prior art charging circuit for a lead acid battery;

Fig. 2 is a schematic structural diagram of an overvoltage and overcurrent charging protection device provided by the invention;

fig. 3 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the invention;

fig. 4 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the invention;

Fig. 5 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the invention;

fig. 6 is a schematic diagram of a lead-acid battery charging circuit according to the present invention.

Detailed Description

The core of the invention is to provide an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit, which avoid frequent on and off of a first controllable switch module through delay treatment on the premise of ensuring the charging protection of a battery, and enhance the practicability and the stability of the overvoltage and overcurrent charging protection device.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1 and 2, fig. 1 is a charging circuit of a lead-acid battery in the prior art; fig. 2 is a schematic structural diagram of an overvoltage and overcurrent charging protection device provided by the invention.

The overvoltage and overcurrent charging protection device comprises a voltage detection module 1, a current detection module 2, a sampling resistor 3, a control module 4 and a first controllable switch module 5;

The charging power supply is connected with the battery to form a charging loop, the first controllable switch module 5 and the sampling resistor 3 are arranged on the charging loop, and the voltage detection module 1 is respectively connected with the charging power supply and the control module 4; the current detection module 2 is respectively connected with the sampling resistor 3 and the control module 4;

The control module 4 is further connected to the control end of the first controllable switch module 5, and is configured to charge when the first controllable switch module 5 is turned off, the voltage detection module 1 determines that the output end of the charging power supply is not over-voltage, and the current detection module 2 determines that the output end of the charging power supply is not over-current, and control the first controllable switch module 5 to be turned on after the charging is finished; discharging when the first controllable switch module 5 is conducted and the voltage detection module 1 judges that the output end of the charging power supply is overvoltage and/or the current detection module 2 judges that the output end of the charging power supply is overcurrent, and controlling the first controllable switch module 5 to be turned off after the discharging is finished; when the first controllable switch module 5 is turned on and the voltage detection module 1 determines that the output end of the charging power supply is not over-voltage and the current detection module 2 determines that the output end of the charging power supply is not over-current, the first controllable switch module 5 is kept controlled to be turned on.

In the embodiment, as described in the background art, the service life of the lead-acid battery is easily reduced by directly charging the lead-acid battery when the charging power supply is improperly selected or damaged; the lead-acid battery charging protection circuit shown in fig. 1 is adopted, when the output voltage of the charging power supply fluctuates at a critical point, the charging power supply is damaged, so that the output voltage of the charging power supply fluctuates greatly, and the output current of the charging power supply flows through, the switching tube Q acts frequently, frequent charging of the lead-acid battery is caused, and the switching tube Q is also easy to thermally break down. In order to solve the technical problems, the application provides an overvoltage and overcurrent charging protection device which avoids frequent charging of a lead-acid battery through delay processing on the premise of ensuring the charging protection of the battery.

Specifically, as shown in fig. 2, when the first controllable switch module 5 is turned on, the charging power source can charge the battery, where the battery can be a lead-acid battery, and the charging power source can be a charger or a direct-current power source, and the application is not limited in particular herein; the voltage detection module 1 is used for judging whether overvoltage occurs at the output end of the charging power supply, the current detection module 2 is used for judging whether overcurrent occurs at the output end of the charging power supply, and then when the first controllable switch module 5 is turned off and the voltage detection module 1 judges that the output end of the charging power supply is not overvoltage and the current detection module 2 judges that the output end of the charging power supply is not overcurrent, the control module 4 firstly charges and controls the first controllable switch module 5 to be turned on after the charging is finished so as to realize the charging of the battery by the charging power supply; when the first controllable switch module 5 is turned on and the voltage detection module 1 determines that the output end of the charging power source is over-voltage and/or the current detection module 2 determines that the output end of the charging power source is over-current, it is stated that the output of the charging power source is abnormal at this time, the control module 4 will firstly discharge and control the first controllable switch module 5 to be turned off after the discharge is finished, when the first controllable switch module 5 is turned on and the voltage detection module 1 determines that the output end of the charging power source is not over-voltage and the current detection module 2 determines that the output end of the charging power source is not over-current, it is stated that the output of the charging power source is normal at this time, then the control module 4 keeps controlling the first controllable switch module 5 to be turned off to stop charging the battery when the first controllable switch module 5 is turned off and the voltage detection module 1 determines that the output end of the charging power source is over-voltage and/or the current detection module 2 determines that the output end of the charging power source is over-current.

It should be noted that, the charging circuit formed by the charging power source and the battery may further include a normally open button for starting charging, and when the user presses the button, the charging circuit is turned on to further ensure the safety of charging, and the application is not limited in particular herein; the time required for the control module 4 to start charging and the time required for the control module 4 to start discharging and the time required for the control module 4 to end discharging are not particularly limited herein, and are determined by the specific circuit configuration set by the user according to actual requirements.

Compared with the prior art, the overvoltage and overcurrent charging protection device provided by the application has the advantages that the frequent on and off of the first controllable switch module 5 are avoided by the charge delay processing and the power-off delay processing on the premise of ensuring the charge protection of the battery, and the practicability and the stability of the overvoltage and overcurrent charging protection device are enhanced aiming at three conditions that the output voltage of the charging power supply fluctuates at a critical point and the output voltage of the charging power supply fluctuates greatly due to the damage of the charging power supply.

Based on the above embodiments:

referring to fig. 3, fig. 3 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the present invention.

As a preferred embodiment, the current detection module 2 comprises a first comparator U1;

The anode of the first comparator U1 is connected with one end of the sampling resistor 3, the cathode of the first comparator U1 is connected with the control module 4, the reference end of the first comparator U1 is connected with the other end of the sampling resistor 3, and is used for being conducted when the output end of the charging power supply is judged to be over-current according to the voltage of the two ends of the sampling resistor 3, and being turned off when the output end of the charging power supply is judged to be not over-current according to the voltage of the two ends of the sampling resistor 3.

In the present application, the current detection module 2 may include a first comparator U1. Specifically, as shown in fig. 3, since the sampling resistor 3 is connected in series in the charging circuit for charging the battery by the charging power supply, the current flowing through the sampling resistor 3 is the current at the output end of the charging power supply. The first comparator U1 is then configured to collect the voltages across the sampling resistor 3 and determine whether the output terminal of the charging source is over-current according to the voltages. Specifically, the determination of whether the output end of the charging power source is over-current can be realized according to the voltages at the two ends of the sampling resistor 3 and the first preset protection threshold value of the first comparator U1, and it is to be noted that the first preset protection threshold value can be determined by reasonably selecting the type of the first comparator U1, and the over-current protection point of the output current of the charging power source can be adjusted by adjusting the resistance value of the sampling resistor 3 and matching with the reasonably selecting the type of the first comparator U1.

It should be noted that, the first comparator U1 may be the controllable precision voltage stabilizing source TL431, which is not particularly limited herein.

It should be further noted that the current detection module 2 may further include a first filter capacitor C1 to implement filtering, where one end of the first filter capacitor C1 is connected to the reference end of the first comparator U1, and the other end of the first filter capacitor C1 is connected to the anode of the first comparator U1.

In this way, it is possible to detect the current at the output of the charging source in a simple and reliable manner, in order to activate the following control module 4.

As a preferred embodiment, the voltage detection module 1 includes a first resistor R1, a second resistor R2, a third resistor R3, a first zener diode DZ1, and a second comparator U2;

One end of the first resistor R1 is respectively connected with the positive electrode of the charging power supply, the positive electrode of the battery and one end of the third resistor R3, the other end of the first resistor R1 is connected with one end of the second resistor R2, the connected common end is connected with the reference end of the second comparator U2, the other end of the second resistor R2 is respectively connected with the negative electrode of the charging power supply, the anode of the second comparator U2, the anode of the first zener diode DZ1 and one end of the sampling resistor 3, and the cathode of the second comparator U2 is connected with the other end of the third resistor R3, and the connected common end is respectively connected with the cathode of the first zener diode DZ1 and the control module 4;

The second comparator U2 is used for being turned on when the voltage of the two ends of the second resistor R2 is used for judging that the output end of the charging power supply is overvoltage, and turned off when the voltage of the two ends of the second resistor R2 is used for judging that the output end of the charging power supply is not overvoltage; the first zener diode DZ1 is used for stabilizing voltage when the first comparator U1 and the second comparator U2 are both turned off, and is turned off when the second comparator U2 and/or the first comparator U1 are turned on.

In the present application, the voltage detection module 1 may include a first resistor R1, a second resistor R2, a third resistor R3, a first zener diode DZ1, and a second comparator U2.

The first resistor R1 and the second resistor R2 divide the voltage of the output end of the charging power supply, the voltage collected by the second comparator U2 is the voltage of the two ends of the second resistor R2, whether the output end of the charging power supply is overvoltage or not is judged according to the voltage, and the third resistor R3 is used for limiting current. Specifically, as shown in fig. 3, when the output end of the charging power supply is not over-voltage, the second comparator U2 is turned off, and at this time, the first zener diode DZ1 is turned on to protect the second comparator U2 from breakdown and damage; when the output end of the charging power supply is over-voltage, the voltage division at two ends of the second resistor R2 is increased, the voltage of the voltage division is larger than a second preset protection threshold value of the second comparator U2, the second comparator U2 is conducted so that the subsequent control module 4 acts, the voltage output by the voltage detection module 1 to the control module 4 is clamped at the conducting voltage between the cathode and the anode of the second comparator U2, and the first voltage stabilizing diode DZ1 is turned off. More specifically, the determination of whether the output end of the charging power source is over-voltage can be realized according to the voltage at the two ends of the second resistor R2 and the second preset protection threshold of the second comparator U2, and it should be noted that the second preset protection threshold can be determined by reasonably selecting the second comparator U2, and the over-voltage protection point of the output voltage of the charging power source can be adjusted by adjusting the resistance value of the first resistor R1 and the resistance value of the second resistor R2 in combination with reasonably selecting the second comparator U2.

It should be noted that, the second comparator U2 may be a controllable precision voltage stabilizing source TL431, and by reasonably selecting the first voltage stabilizing diode DZ1, the voltage across the second comparator U2 may be clamped when the second comparator U2 is not turned on, and the clamping voltage may be 36V.

It should be further noted that the voltage detection module 1 may further include a second filter capacitor C2 to implement filtering, where one end of the second filter capacitor C2 is connected to the reference end of the second comparator U2, and the other end of the second filter capacitor C2 is connected to the anode of the second comparator U2.

In this way, it is possible to detect the voltage at the output of the charging source in a simple and reliable manner, in order to activate the following control module 4.

As a preferred embodiment, the voltage detection module 1 further comprises a fourth resistor R4 and a first controllable switch Q1;

one end of a fourth resistor R4 is connected with one end of a second resistor R2, and the other end of the fourth resistor R4 is connected with the first end of the first controllable switch Q1;

The second end of the first controllable switch Q1 is connected with the other end of the second resistor R2, and the control end of the first controllable switch Q1 is connected with the control end of the first controllable switch module 5 and is used for being turned on when the first controllable switch module 5 is turned on and turned off when the first controllable switch module 5 is turned off;

The switching on when judging that the output end of the charging power supply is overvoltage according to the voltage of the two ends of the second resistor R2, and the switching off when judging that the output end of the charging power supply is not overvoltage according to the voltage of the two ends of the second resistor R2 comprises the following steps:

the voltage detection circuit is turned on when the voltage of the two ends of the equivalent resistor is used for judging that the output end of the charging power supply is overvoltage according to the voltage of the two ends of the second resistor R2 and the voltage of the four ends of the equivalent resistor R4 which are connected in parallel, and turned off when the voltage of the two ends of the second resistor R2 is not overvoltage.

In this embodiment, the inventor further aims at the situation that the output voltage of the charging power supply fluctuates at the critical point, and the voltage detection module 1 may further include a fourth resistor R4 and a first controllable switch Q1.

Specifically, when the output end of the charging power supply is not over-voltage and does not over-current, the first controllable switch module 5 is turned on to realize charging of the charging power supply to the battery, at this time, the first controllable switch Q1 is also turned on, then the fourth resistor R4 is connected in parallel with the second resistor R2, the second comparator U2 determines whether the output end of the charging power supply is over-voltage according to the voltages at two ends of the equivalent resistor after the second resistor R2 and the fourth resistor R4 are connected in parallel, more specifically, at this time, the determination of whether the output end of the charging power supply is over-voltage can be realized according to the voltages at two ends of the equivalent resistor after the second resistor R2 and the fourth resistor R4 are connected in parallel and the second preset protection threshold of the second comparator U2, and it is required to be noted that the second preset protection threshold can be determined by reasonably selecting the second comparator U2, and the protection point for over-voltage of the charging power supply can be adjusted by adjusting the resistance value of the first resistor R1, the resistance value of the second resistor R2, and the resistance value of the fourth resistor R4 in cooperation with the reasonable selection of the second comparator U2. Then when the output end of the charging power supply is over-voltage and not over-current, the first controllable switch module 5 is still in a conducting state, the second comparator U2 judges that the output end of the charging power supply is over-voltage and conducting according to the voltage at two ends of the equivalent resistor after the second resistor R2 and the fourth resistor R4 are connected in parallel, the control module 4 firstly discharges and controls the first controllable switch module 5 to turn off after the discharging is finished, at this time, the first controllable switch Q1 is also turned off, the fourth resistor R4 is cut off from the circuit, and then the second comparator U2 judges whether the output end of the charging power supply is not over-voltage any more only according to the voltage at two ends of the second resistor R2, so that the voltage at two ends of the second resistor R2 can be reduced only to lower voltage values to enable the second comparator U2 to turn off, and it is to be noted that the regulation of the voltage value which needs to be reduced to be at most when the charging is recovered can be achieved by regulating the resistance value of the second resistor R2. If the output terminal of the charging power supply is not over-voltage and not over-current, the control module 4 will charge and control the first controllable switch module 5 to be turned on after the charging is finished so as to resume the charging of the battery by the charging power supply.

It should be noted that, the first controllable switch Q1 may be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, metal-Oxide semiconductor field effect transistor), the gate of the MOSFET is used as the control terminal of the first controllable switch Q1, the source of the MOSFET is used as the second terminal of the first controllable switch Q1, the drain of the MOSFET is used as the first terminal of the first controllable switch Q1, and the MOSFET may further include a body diode to drain the energy remaining when the MOSFET is turned off.

Therefore, the method can realize reliable protection of overvoltage condition of the output end of the charging power supply, better solves the problem of battery charging protection of the output voltage of the charging power supply under the fluctuation of the critical point, ensures that the overvoltage protection is more stable, and has simple circuit.

Referring to fig. 4, fig. 4 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the present invention.

As a preferred embodiment, the voltage detection module 1 further includes a fifth resistor R5, a second zener diode DZ2, a third zener diode DZ3, an optocoupler U3, a second controllable switch Q2, and a sixth resistor R6;

One end of a fifth resistor R5 is respectively connected with one end of the first resistor R1 and the cathode of the second zener diode DZ2, and the other end of the fifth resistor R5 is connected with the first end of the second controllable switch Q2;

The light emitting diode of the optocoupler U3 is connected between the other end of the third resistor R3 and the cathode of the second comparator U2, the anode of the light emitting diode is respectively connected with the other end of the third resistor R3 and the cathode of the first zener diode DZ1, the cathode of the light emitting diode is connected with the cathode of the second comparator U2, the collector of the phototriode of the optocoupler U3 is connected with the anode of the third zener diode DZ3, the emitter of the phototriode is connected with one end of the sixth resistor R6, and the light emitting diode is used for being turned on when the second comparator U2 is turned on, and turned off when the second comparator U2 is turned off; the phototriode is used for being conducted when the light emitting diode is conducted, and being turned off when the light emitting diode is turned off;

The other end of the sixth resistor R6 is connected with the anode of the second comparator U2; the second zener diode DZ2 is used for voltage stabilization; the third zener diode DZ3 is used for voltage stabilization;

The second end of the second controllable switch Q2 is respectively connected with the other end of the first resistor R1 and the reference end of the second comparator U2, and the control end of the second controllable switch Q2 is respectively connected with the anode of the second zener diode DZ2 and the cathode of the third zener diode DZ3, and is used for being conducted when the phototriode is conducted and being turned off when the phototriode is turned off.

In this embodiment, the inventor further aims at the situation that the output voltage of the charging power source fluctuates at the critical point, and the voltage detection module 1 may further include a fifth resistor R5, a second zener diode DZ2, a third zener diode DZ3, an optocoupler U3, a second controllable switch Q2, and a sixth resistor R6.

Specifically, as shown in fig. 4, when the output end of the charging power supply is not over-voltage, the second comparator U2 is turned off to turn off the light emitting diode of the optocoupler U3, the phototransistor of the optocoupler U3 is turned off, the second controllable switch Q2 is turned off, the fifth resistor R5 does not participate in voltage sampling, and at this time, the resistor for voltage sampling only has the first resistor R1 and the second resistor R2;

When the output end of the charging power supply is over-voltage, the second comparator U2 is conducted, so that the light emitting diode of the optocoupler U3 is conducted, the phototriode of the optocoupler U3 is conducted, the second controllable switch Q2 is conducted, the fifth resistor R5 is connected with the first resistor R1 in parallel to participate in voltage sampling, and further the voltage at the two ends of the second resistor R2 is further increased to form positive feedback, so that protection at an over-voltage critical point of the output voltage of the charging power supply is more stable, more specifically, whether the output end of the charging power supply is over-voltage or not can be judged according to the voltage at the two ends of the second resistor R2 and a second preset protection threshold of the second comparator U2, and the fact that the second preset protection threshold can be determined through reasonable selection of the second comparator U2 can be achieved, and the over-voltage protection point of the output voltage of the charging power supply can be adjusted through adjusting the resistance value of the first resistor R1, the resistance value of the second resistor R2 and the resistance value of the fifth resistor R5 in cooperation with reasonable selection of the second comparator U2 is needed; it should be noted that, the adjustment of the voltage value that needs to be reduced by at most a large value when the charging is resumed can be achieved by adjusting the resistance value of the fifth resistor R5, and the present application is not limited in particular herein; the second zener diode DZ2 is used for stabilizing voltage to protect the second controllable switch Q2; the third zener diode DZ3 is used for stabilizing voltage to protect the optocoupler U3; the sixth resistor R6 is used for current limiting.

It should be further noted that, the voltage detection module 1 may further include a fifteenth resistor R15, where one end of the fifteenth resistor R15 is connected to the cathode of the second zener diode DZ2, and the other end of the fifteenth resistor R15 is connected to the anode of the second zener diode DZ2, so as to pull the control end and the first end of the second controllable switch Q2 to an equipotential value to ensure that the second controllable switch Q2 is stably turned off when the optocoupler U3 is not turned on; it should be further noted that, the second controllable switch Q2 may be a MOSFET, where a gate of the MOSFET is used as a control terminal of the second controllable switch Q2, a source of the MOSFET is used as a first terminal of the second controllable switch Q2, a drain of the MOSFET is used as a second terminal of the second controllable switch Q2, and the MOSFET may further include a body diode to drain energy remaining when the MOSFET itself is turned off, and the present application is not limited herein.

Therefore, the positive feedback of the voltage can be added in the mode, so that the output voltage of the charging power supply needs to be reduced to a lower output voltage when the output end of the charging power supply is overvoltage so as to restore the charging of the battery, the problem of battery charging protection of the output voltage of the charging power supply under the fluctuation of a critical point is better solved, and the overvoltage protection is more stable.

As a preferred embodiment, the first controllable switch module 5 includes a third controllable switch Q3 and a fourth zener diode DZ4;

the control end of the third controllable switch Q3 is connected with the cathode of the fourth zener diode DZ4, the public end connected with the cathode of the fourth zener diode DZ4 is used as the control end of the first controllable switch module 5, the first end of the third controllable switch Q3 is connected with the anode of the fourth zener diode DZ4, the public end connected with the anode of the fourth zener diode DZ4 is connected with the other end of the sampling resistor 3, and the second end of the third controllable switch Q3 is connected with the cathode of the battery.

In this embodiment, the first controllable switch module 5 may include a third controllable switch Q3 and a fourth zener diode DZ4, where the third controllable switch Q3 may be a MOSFET, a gate of the MOSFET is used as a control terminal of the third controllable switch Q3, a source of the MOSFET is used as a first terminal of the third controllable switch Q3, a drain of the MOSFET is used as a second terminal of the third controllable switch Q3, and the MOSFET may further include a body diode to drain energy remaining when the MOSFET is turned off.

The fourth zener diode DZ4 may realize voltage stabilization, and in order to further stabilize the voltage between the gate and the source when the third controllable switch Q3 is turned on, the first controllable switch module 5 may further include a sixteenth resistor R16, one end of the sixteenth resistor R16 is connected to the cathode of the fourth zener diode DZ4, and the other end of the sixteenth resistor R16 is connected to the anode of the fourth zener diode DZ 4.

It can be seen that in this way the control logic of the first controllable switch module 5 can be implemented simply and reliably.

As a preferred embodiment, the control module 4 includes a first diode D1, a capacitor E, a fourth controllable switch Q4, a seventh resistor R7, an eighth resistor R8, a fifth zener diode DZ5, a fifth controllable switch Q5, and a sixth controllable switch Q6;

The cathode of the first diode D1 is respectively connected with the cathode of the first zener diode DZ1, the cathode of the first comparator U1, the first end of the sixth controllable switch Q6 and one end of the seventh resistor R7, the anode of the first diode D1 is connected with the control end of the fourth controllable switch Q4, and is used for being turned on when the second comparator U2 and/or the first comparator U1 are turned on, and turned off when the second comparator U2 and the first comparator U1 are turned off;

The other end of the seventh resistor R7 is connected with one end of a capacitor E, a public end connected with the capacitor E is respectively connected with the first end of the fourth controllable switch Q4 and the cathode of the fifth voltage stabilizing diode DZ5, the other end of the capacitor E is respectively connected with the other end of the sampling resistor 3, one end of the eighth resistor R8 and the second end of the fifth controllable switch Q5, and the capacitor E is used for charging when the first controllable switch module 5 is turned off, the first comparator U1 is turned off, and the second comparator U2 is turned off; discharging when the first controllable switch module 5 is turned on and the first comparator U1 is turned on and/or the second comparator U2 is turned on;

The second end of the fourth controllable switch Q4 is connected with the other end of the eighth resistor R8 and is used for being turned on when the first diode D1 is turned on and turned off when the first diode D1 is turned off;

The fifth zener diode DZ5 is configured to be turned on when the capacitor E is charged and turned off when the capacitor E is discharged and remain turned on when the first controllable switch Q1, the first controllable switch module 5, the first comparator U1, and the second comparator U2 are turned off;

The control end of the fifth controllable switch Q5 is connected with the anode of the fifth zener diode DZ5, and the first end of the fifth controllable switch Q5 is connected with the control end of the sixth controllable switch Q6 and is used for being turned on when the fifth zener diode DZ5 is turned on and turned off when the fifth zener diode DZ5 is turned off;

The control end of the sixth controllable switch Q6 is connected to the control end of the first controllable switch module 5 of the first controllable switch Q1, and is used for being turned on when the fifth controllable switch Q5 is turned on to control the first controllable switch module 5 to be turned on, and turned off when the fifth controllable switch Q5 is turned off to control the first controllable switch module 55 to be turned off.

In the present application, the control module 4 may include a first diode D1, a capacitor E, a fourth controllable switch Q4, a seventh resistor R7, an eighth resistor R8, a fifth zener diode DZ5, a fifth controllable switch Q5, and a sixth controllable switch Q6.

Specifically, when the first controllable switch module 5 is turned off and the output end of the charging power supply is not over-voltage and not over-current, the first comparator U1 is turned off, the second comparator U2 is turned off, the charging power supply charges the capacitor E through the third resistor R3 and the seventh resistor R7, and the charging time of the capacitor E depends on the resistance values of the third resistor R3 and the seventh resistor R7 and the capacitance of the capacitor E. Along with the rising of the voltage at two ends of the capacitor E, when the voltage at two ends of the capacitor E is larger than the breakdown voltage of the fifth zener diode DZ5, the fifth zener diode DZ5 is conducted, so that the fifth controllable switch Q5 is conducted in a delayed mode, the sixth controllable switch Q6 is conducted in a delayed mode, the first controllable switch module 5 is controlled to conduct in a delayed mode, and the battery is charged in a delayed mode by the charging power supply; it should be noted that, when the output end of the charging power supply is not over-voltage and not over-current all the time, the negative voltage of the first diode D1 will not be smaller than the positive voltage of the capacitor E all the time, so the first diode D1 and the fourth controllable switch Q4 remain turned off all the time.

When the first controllable switch module 5 is turned on and the output terminal of the charging power source is over-voltage and/or over-current, please refer to fig. 4, the control process is described by taking the case that the output terminal of the charging power source is over-voltage and not over-current as an example: at this time, the second comparator U2 is turned on, the light emitting diode of the optocoupler U3 is turned on, so that the first diode D1 is turned on, the fourth controllable switch Q4 is turned on, at this time, the capacitor E forms a first discharge loop through the fourth controllable switch Q4 and the eighth resistor R8 to perform the first discharge, then, the second discharge loop is further formed by the first diode D1, the anode and the cathode of the light emitting diode of the optocoupler U3, the cathode and the anode of the second comparator U2, and the fourth resistor R4 to perform the second discharge, and finally, the voltage at two ends of the capacitor E is clamped to be the sum of the turn-on voltage drop of the light emitting diode of the optocoupler U3 and the turn-on voltage drop of the cathode and the anode of the second comparator U2, at this time, the clamping voltage at two ends of the capacitor E is smaller than the reverse breakdown voltage of the fifth diode DZ5 through reasonably selecting the fifth diode DZ5, so that the fifth diode DZ5 is turned off, and the fifth controllable switch Q5 and the sixth controllable switch Q6 are turned off, thereby realizing the time delay of the power supply turn-off of the first controllable switch 5.

It should be noted that, the fourth controllable switch Q4 may be a PNP-type triode, where a base electrode of the PNP-type triode is used as a control end of the fourth controllable switch Q4, an emitter electrode of the PNP-type triode is used as a first end of the fourth controllable switch Q4, and a collector electrode of the PNP-type triode is used as a second end of the fourth controllable switch Q4; the fifth controllable switch Q5 may be an NPN-type triode, a base electrode of the NPN-type triode is used as a control end of the fifth controllable switch Q5, an emitter electrode of the NPN-type triode is used as a second end of the fifth controllable switch Q5, and a collector electrode of the NPN-type triode is used as a first end of the fifth controllable switch Q5, and it should be noted that, in order to ensure stable conduction of the NPN-type triode, the control module 4 may further include a seventeenth resistor R17, one end of the seventeenth resistor R17 is connected with the base electrode of the NPN-type triode, and the other end of the seventeenth resistor R17 is connected with the emitter electrode of the NPN-type triode; the sixth controllable switch Q6 may be a PNP-type triode, the base of the PNP-type triode is used as the control terminal of the sixth controllable switch Q6, the emitter of the PNP-type triode is used as the first terminal of the sixth controllable switch Q6, and the collector of the PNP-type triode is used as the second terminal of the sixth controllable switch Q6, and it should be noted that, in order to ensure stable conduction of the PNP-type triode, the control module 4 may further include an eighteenth resistor R18, one end of the eighteenth resistor R18 is connected to the base of the PNP-type triode, and the other end of the eighteenth resistor R18 is connected to the emitter of the PNP-type triode.

It should be noted that, the seventh resistor R7 has a relatively large resistance, so that the charging time of the capacitor E can be delayed, and the eighth resistor R8 has a relatively small resistance, so that the discharging of the capacitor E can be realized.

It can be seen that in this way the control logic of the control module 4 can be implemented stably and reliably to implement the delay processing of charging and de-charging the battery by the charging source.

As a preferred embodiment, the circuit further comprises a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a sixth zener diode DZ6;

one end of a ninth resistor R9 is connected with the positive electrode of the charging power supply, the other end of the ninth resistor R9 is connected with one end of a tenth resistor R10, the connected common end is connected with the cathode of a sixth zener diode DZ6, the other end of the tenth resistor R10 is connected with one end of an eleventh resistor R11, the connected common end is connected with the reference end of a first comparator U1, the other end of the eleventh resistor R11 is respectively connected with the other end of a sampling resistor 3 and the anode of the sixth zener diode DZ6, and the zener diode is used for providing stable voltage;

The switching on when judging that the output end of the charging power supply is over-current according to the voltage of the two ends of the sampling resistor 3, and the switching off when judging that the output end of the charging power supply is not over-current according to the voltage of the two ends of the sampling resistor 3 comprises the following steps:

The power supply is turned on when the output end of the charging power supply is judged to be overcurrent according to the sum of the voltages of the two ends of the sampling resistor 3 and the voltages of the two ends of the eleventh resistor R11, and turned off when the output end of the charging power supply is judged to be not overcurrent according to the sum of the voltages of the two ends of the sampling resistor 3 and the voltages of the two ends of the eleventh resistor R11.

In this embodiment, the inventor further considers that in the lead-acid battery charging protection circuit shown in fig. 1 in the prior art, the resistance value of the sampling resistor is difficult to determine, and if the resistance value of the sampling resistor is selected to be too small, a comparison voltage larger than a preset comparison reference of the comparator A2 may not be provided when the output current of the charger flows excessively, so that the overcurrent protection is disabled; when the resistance value of the sampling resistor is excessively large, the voltage and the power consumption at two ends of the sampling resistor can be large during normal charging, so that the charging of the lead-acid battery is influenced, and even the lead-acid battery cannot be charged. In order to solve the above technical problem, the overvoltage/overcurrent charging protection device of the present application may further include a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a sixth zener diode DZ6.

Specifically, the ninth resistor R9 is used for limiting current, the sixth zener diode DZ6 can provide stable voltage during operation, the tenth resistor R10 and the eleventh resistor R11 divide the stable voltage, so when the first comparator U1 determines whether the output end of the charging power supply is over-current or not according to the sum of the voltages at the two ends of the sampling resistor 3 and the voltages at the two ends of the eleventh resistor R11, this makes reasonable selection of the resistance value of the tenth resistor R10, the resistance value of the eleventh resistor R11 and the magnitude of the stable voltage which can be provided by the sixth zener diode DZ6, the resistance value of the sampling resistor 3 can be selected to be smaller, more specifically, the determination whether the output end of the charging power supply is over-current or not can be realized according to the sum of the voltages at the two ends of the sampling resistor 3 and the voltages at the two ends of the eleventh resistor R11 and the first preset protection threshold of the first comparator U1, it is necessary to be explained that the first preset protection threshold can be determined whether the output end of the charging power supply is over-current or not through reasonable selection of the sampling resistor U1, the resistance value of the eleventh resistor R11 and the value of the eleventh resistor R11 can be adjusted by reasonably selecting the magnitude of the stable voltage which can be provided by adjusting the resistance value of the tenth resistor R10 and the resistance value of the eleventh resistor R6.

It can be seen that the function of the current detection module 2 is realized in this way, and the sampling resistor 3 can be made to select a smaller value to reduce the power consumption and voltage during normal operation thereof, so as to reduce the influence on the charging of the lead-acid battery as much as possible.

Referring to fig. 5, fig. 5 is a schematic structural diagram of another overvoltage and overcurrent charging protection device provided by the present invention.

As a preferred embodiment, the circuit further comprises a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a third comparator U4;

the reference end of the third comparator U4 is connected with the cathode of the third comparator U4, and the connected common end is respectively connected with one end of the twelfth resistor R12 and one end of the thirteenth resistor for providing stable voltage;

The other end of the twelfth resistor R12 is connected with the positive electrode of the charging power supply, the other end of the thirteenth resistor R13 is connected with one end of the fourteenth resistor R14, the connected common end is connected with the reference end of the first comparator U1, and the other end of the fourteenth resistor R14 is respectively connected with the other end of the sampling resistor 3 and the anode of the third comparator U4;

The power supply is turned on when the output end of the charging power supply is judged to be overcurrent according to the sum of the voltages of the two ends of the sampling resistor 3 and the voltages of the two ends of the fourteenth resistor R14, and turned off when the output end of the charging power supply is judged to be not overcurrent according to the sum of the voltages of the two ends of the sampling resistor 3 and the voltages of the two ends of the fourteenth resistor R14.

In this embodiment, the inventor provides another solution to the problem that the resistance of the sampling resistor 3 is difficult to determine in the prior art, that is, the overvoltage/overcurrent charging protection device may further include a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a third comparator U4.

Specifically, the twelfth resistor R12 is used for limiting current, the third comparator U4 is connected in such a manner that it can provide a stable voltage during operation, the thirteenth resistor R13 and the fourteenth resistor R14 divide the stable voltage, so when the first comparator U1 determines whether the output end of the charging power supply is over-current or not according to the sum of the voltages at both ends of the sampling resistor 3 and the voltages at both ends of the fourteenth resistor R14, this makes a reasonable choice between the resistance value of the thirteenth resistor R13, the resistance value of the fourteenth resistor R14 and the stable voltage that can be provided by the third comparator U4, the resistance value of the sampling resistor 3 can be selected to be smaller, more specifically, the first preset protection threshold of the first comparator U1 can determine whether the output end of the charging power supply is over-current or not according to the sum of the voltages at both ends of the sampling resistor 3 and the voltages at both ends of the fourteenth resistor R14, it needs to be explained that the first preset protection threshold of the first comparator U1 can reasonably decide whether the output end of the charging power supply is over-current or not through the first comparator U1, and the value of the thirteenth resistor R13, the resistance value of the thirteenth resistor R14 can be reasonably adjusted by adjusting the resistance value of the sampling resistor U1 and the third comparator U4.

It can be seen that the function of the current detection module 2 is also realized in this way, and the sampling resistor 3 can select a smaller value to reduce the power consumption and the voltage during the normal operation of the sampling resistor, so as to reduce the influence on the charging of the lead-acid battery as much as possible, and the voltage stabilizing performance is better in a third comparator U4 manner, so that the precision of the stable voltage provided by the sampling resistor is improved, and the overcurrent protection of the output current of the charging power supply is more accurate.

It should be noted that, the third comparator U4 may be the controllable precision voltage stabilizing source TL431, and the present application is not limited thereto.

Referring to fig. 6, fig. 6 is a schematic structural diagram of a charging circuit for a lead-acid battery according to the present invention.

The lead-acid battery charging circuit comprises a lead-acid battery and a charging power supply, and further comprises the overvoltage and overcurrent charging protection device 6, wherein the charging power supply, the overvoltage and overcurrent charging protection device 6 and the lead-acid battery are connected in sequence.

For the introduction of the lead-acid battery charging circuit provided by the present invention, please refer to the embodiment of the above-mentioned overvoltage and overcurrent charging protection device 6, and the disclosure is not repeated here.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

It should also be noted that in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

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

Claims

1. The overvoltage and overcurrent charging protection device is characterized by comprising a voltage detection module, a current detection module, a sampling resistor, a control module and a first controllable switch module;

2. The overvoltage/overcurrent charge protection device of claim 1, wherein the current detection module includes a first comparator;

3. The device of claim 2, wherein the voltage detection module comprises a first resistor, a second resistor, a third resistor, a first zener diode, and a second comparator;

4. The overvoltage/overcurrent charge protection device of claim 3 wherein the voltage detection module further includes a fourth resistor and a first controllable switch;

And the output end of the charging power supply is judged to be over-voltage according to the voltage of the two ends of the equivalent resistor after the second resistor and the fourth resistor are connected in parallel, and the output end of the charging power supply is judged to be not over-voltage according to the voltage of the two ends of the second resistor.

5. The device of claim 3, wherein the voltage detection module further comprises a fifth resistor, a second zener diode, a third zener diode, an optocoupler, a second controllable switch, and a sixth resistor;

6. The overvoltage/overcurrent charge protection device according to any one of claims 2 to 5, wherein the first controllable switch module includes a third controllable switch and a fourth zener diode;

7. The overvoltage/overcurrent charge protection device according to any one of claims 3 to 5, wherein the control module includes a first diode, a capacitor, a fourth controllable switch, a seventh resistor, an eighth resistor, a fifth zener diode, a fifth controllable switch, and a sixth controllable switch;

8. The overvoltage/overcurrent charge protection device according to any one of claims 3 to 5, further comprising a ninth resistor, a tenth resistor, an eleventh resistor, and a sixth zener diode;

9. The overvoltage/overcurrent charge protection device according to any one of claims 3 to 5, further comprising a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a third comparator;

10. A lead-acid battery charging circuit comprising a lead-acid battery and a charging power supply, and further comprising an overvoltage and overcurrent charging protection device according to any one of claims 1 to 9, wherein the charging power supply, the overvoltage and overcurrent charging protection device and the lead-acid battery are connected in sequence.