CN114336885A

CN114336885A - Overvoltage and overcurrent charging protection device and lead-acid battery charging circuit

Info

Publication number: CN114336885A
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: 2022-04-12
Anticipated expiration: 2042-01-07
Also published as: CN114336885B

Abstract

The invention discloses an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit.A control module in the device is used for charging when a first controllable switch module is switched off and the output end of a charging power supply is not overvoltage and overcurrent, and controlling the first controllable switch module to be switched on after the charging is finished, so that the delayed charging of the charging power supply on a battery is realized; and discharging when the first controllable switch module is switched on and the output end of the charging power supply is in overvoltage and/or overcurrent, and controlling the first controllable switch module to be switched off after the discharging is finished, so that the delayed power-off of the charging power supply to the battery is realized. According to the scheme, the output voltage of the charging power supply fluctuates at a critical point, the charging power supply is damaged, the output voltage fluctuates greatly, and the output current of the charging power supply overflows, on the premise that the charging protection of the battery is guaranteed, the first controllable switch module is prevented from being frequently switched on and off through the time delay processing, 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 significant portion of the market as a low-cost and relatively safe battery. For charging lead-acid batteries, the following methods are generally adopted in the prior art: one is to use a charger or a direct current power supply to directly charge the lead-acid battery, however, the technical indexes of the charger and the direct current power supply are different, if the charger or the direct current power supply is improperly selected or the lead-acid battery is damaged in use, because the method has no corresponding protection circuit, the lead-acid battery is easily subjected to overvoltage or overcurrent charging for a long time, and the service life of the lead-acid battery is seriously influenced.

The second mode is to add a charging protection circuit on the charging loop of the lead-acid battery. Therefore, referring to fig. 1, fig. 1 is a charging circuit of a lead-acid battery in the prior art for 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 in overvoltage 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 switching tube Q to be turned off when the output current of the charger is over-current so that the lead-acid battery cannot be charged, and therefore the protection of the charging of the lead-acid battery is completed. However, this method has many problems, one of which is that when the charging voltage fluctuates at the overvoltage critical point or the charger is damaged, the comparator a1 immediately responds to control the switching tube Q to turn on and off, which results in frequent charging of the lead-acid battery, and when the output current is large, the switching tube Q will generate large switching loss, which is likely to be thermally broken down; secondly, when the output current of the charger is overcurrent, the comparator a2 immediately responds to control the on and off of the switching tube Q, and this frequent action also causes frequent charging of the lead-acid battery, and when the output current is large, the switching tube Q will generate large 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 time delay processing on the premise of ensuring the charging protection of a battery, and enhance the practicability and stability of the overvoltage and overcurrent charging protection device.

In order to solve the technical problem, 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, wherein the voltage detection module is used for detecting the voltage of the voltage detection module;

the charging power supply is connected with a 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 and the voltage detection module determines that the output end of the charging power supply is not overvoltage and the current detection module determines that the output end of the charging power supply is not overcurrent and controlling the first controllable switch module to be turned on after the charging is finished; when the first controllable switch module is switched on and the voltage detection module judges that the output end of the charging power supply is in overvoltage and/or the current detection module judges that the output end of the charging power supply is in overcurrent, discharging is carried out, and the first controllable switch module is controlled to be switched off after the discharging 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 overvoltage, and the current detection module judges that the output end of the charging power supply is not overcurrent, the first controllable switch module is kept to be conducted.

Preferably, the current detection module comprises 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 being switched on when the output end of the charging power supply is judged to be overcurrent according to the voltages at the two ends of the sampling resistor and being switched off when the output end of the charging power supply is judged not to be overcurrent according to the voltages at the two ends of the sampling resistor.

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

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

the second comparator is used for conducting when the output end of the charging power supply is judged to be overvoltage according to the voltage at the two ends of the second resistor, and switching off when the output end of the charging power supply is judged to be not overvoltage according to the voltage at the two ends of the second resistor; 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 switched on when the first controllable switch module is switched on and being switched off when the first controllable switch module is switched off;

the switch-on is carried out when the output end of the charging power supply is judged to be overvoltage according to the voltage at two ends of the second resistor, and the switch-off is carried out when the output end of the charging power supply is judged to be not overvoltage according to the voltage at two ends of the second resistor, and the switch-off comprises the following steps:

the charging power supply is connected with the first resistor and the second resistor in parallel, the output end of the charging power supply is connected with the second resistor, the second resistor is connected with the fourth resistor in parallel, the output end of the charging power supply is connected with the second resistor, the first resistor is connected with the second resistor, the second resistor is connected with the fourth resistor in parallel, the output end of the charging power supply is connected with the second resistor in parallel, the output end of the charging power supply is connected with the fourth resistor in parallel, and the output end of the charging power supply is connected with the fourth resistor in parallel.

Preferably, the voltage detection module further includes a fifth resistor, a second voltage regulator diode, a third voltage regulator 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 voltage stabilizing 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 voltage stabilizing 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 voltage stabilizing diode, the emitter of the phototriode is connected with one end of the sixth resistor, and the light emitting diode is used for being switched on when the second comparator is switched on and switched off when the second comparator is switched off; the phototriode is used for being conducted when the light emitting diode is conducted 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 voltage stabilizing diode is used for stabilizing voltage;

the second end of the second controllable switch is connected with the other end of the first resistor and the reference end of the second comparator respectively, and the control end of the second controllable switch is connected with the anode of the second voltage stabilizing diode and the cathode of the third voltage stabilizing diode respectively and used for conducting when the phototriode is conducted and switching off when the phototriode is switched off.

Preferably, the first controllable switch module includes 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, the connected public end of the control end of the third controllable switch 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, the connected public end of the third controllable switch 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 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;

the cathode of the first diode is respectively connected with the cathode of the first voltage stabilizing diode, the cathode of the first comparator, the first end of the sixth controllable switch and one end of the seventh resistor, the anode of the first diode is connected with the control end of the fourth controllable switch, and the first diode 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 connected common end of the seventh resistor is respectively connected with a first end of the fourth controllable switch and a cathode of the fifth voltage-stabilizing diode, the other end of the capacitor is respectively connected with the other end of the sampling resistor, one end of the eighth resistor and a second end of the fifth controllable switch, 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;

a 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 voltage stabilizing diode is used for being conducted when the capacitor is charged, being turned off when the capacitor is discharged, and being kept conducted when the first controllable switch module is conducted, the first comparator is turned off and the second comparator is turned off;

a control end of the fifth controllable switch is connected with an anode of the fifth voltage-stabilizing diode, and a first end of the fifth controllable switch is connected with a control end of the sixth controllable switch, and is used for conducting when the fifth voltage-stabilizing diode is conducted and for turning off when the fifth voltage-stabilizing diode is turned off;

and 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 switched on when the fifth controllable switch is switched on to control the first controllable switch module to be switched on, and being switched off when the fifth controllable switch is switched off to control the first controllable switch module to be switched 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 anode of the charging power supply, the other end of the ninth resistor is connected with one end of the tenth resistor, the connected common end of the ninth resistor and the tenth resistor is connected with the cathode of the sixth voltage-stabilizing 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 and the eleventh 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 voltage-stabilizing diode, and the voltage-stabilizing diode is used for providing stable voltage;

the output end of the charging power supply is conducted when overcurrent is judged according to the voltages at the two ends of the sampling resistor, and the output end of the charging power supply is turned off when overcurrent is judged according to the voltages at the two ends of the sampling resistor, and the method comprises the following steps:

and the charging circuit is switched on when the output end of the charging power supply is judged to be overcurrent according to the sum of the voltages at the two ends of the sampling resistor and the voltage at the two ends of the eleventh resistor, and is switched off when the output end of the charging power supply is judged to be not overcurrent according to the sum of the voltages at the two ends of the sampling resistor and the voltage at 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;

a reference end of the third comparator is connected with a cathode of the third comparator, and a 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 public end of the thirteenth resistor 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 positive electrode of the third comparator;

and the charging circuit is switched on when the output end of the charging power supply is judged to be overcurrent according to the sum of the voltages at the two ends of the sampling resistor and the voltage at the two ends of the fourteenth resistor, and is switched off when the output end of the charging power supply is judged to be not overcurrent according to the sum of the voltages at the two ends of the sampling resistor and the voltage at the two ends of the fourteenth resistor.

In order to solve the technical problem, the invention further 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 sequentially connected.

The invention provides an overvoltage and overcurrent charging protection device and a lead-acid battery charging circuit, wherein a charging power supply can charge a battery when a first controllable switch module in the device is switched on, so that a control module in the device charges when the first controllable switch module is switched 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 switched on after the charging is finished, so that the charging power supply can charge the battery in a delayed manner; when the first controllable switch module is switched on and the voltage detection module judges that the output end of the charging power supply is in overvoltage and/or the current detection module judges that the output end of the charging power supply is in overcurrent, the first controllable switch module is controlled to be switched off after the discharging is finished, and therefore the delayed power-off of the charging power supply to the battery is realized. Compared with the prior art, the scheme has the advantages that the output voltage of the charging power supply fluctuates at a critical point, the charging power supply is damaged, the output voltage fluctuates greatly, and the output current of the charging power supply overflows, so that the first controllable switch module is prevented from being frequently switched on and off through the time delay processing on the premise of ensuring the charging protection of the battery, and the practicability and the stability of the overvoltage and overcurrent charging protection device are enhanced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

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

fig. 2 is a schematic structural diagram of an overvoltage/overcurrent charging protection device provided by the present invention;

fig. 3 is a schematic structural diagram of another over-voltage and over-current charging protection device provided by the present invention;

fig. 4 is a schematic structural diagram of another over-voltage over-current charging protection device provided by the present invention;

fig. 5 is a schematic structural diagram of another over-voltage over-current charging protection device provided by the present invention;

fig. 6 is a schematic structural diagram of a charging circuit for a lead-acid battery 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-off of a first controllable switch module through time delay processing on the premise of ensuring the charging protection of a battery, and enhance the practicability and stability of the overvoltage and overcurrent charging protection device.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and fig. 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/overcurrent charging protection device provided by the present 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 with a control end of the first controllable switch module 5, and is used for charging 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 supply is not overvoltage and the current detection module 2 determines that the output end of the charging power supply is not overcurrent, and controlling the first controllable switch module 5 to be turned on after the charging is finished; when the first controllable switch module 5 is switched on and the voltage detection module 1 judges that the output end of the charging power supply is in overvoltage and/or the current detection module 2 judges that the output end of the charging power supply is in overcurrent, discharging is carried out, and the first controllable switch module 5 is controlled to be switched off after 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 overvoltage and the current detection module 2 determines that the output end of the charging power supply is not overcurrent, the first controllable switch module 5 is kept controlled to be turned on.

In the present embodiment, it is considered that, as described in the background art, when the type of the charging power supply is improperly selected or the charging power supply itself is damaged, directly using it to charge the lead-acid battery easily reduces the service life of the lead-acid battery; in the lead-acid battery charging protection circuit shown in fig. 1, in the face of three conditions that the output voltage of a charging power supply fluctuates at a critical point, the output voltage of the charging power supply fluctuates greatly due to damage of the charging power supply, and the output current of the charging power supply is overcurrent, a switching tube Q can frequently act, so that the lead-acid battery is frequently charged, and the switching tube Q is easily subjected to thermal breakdown. In order to solve the technical problem, the application provides an overvoltage and overcurrent charging protection device, and the device avoids frequent charging of a lead-acid battery through time delay processing on the premise of ensuring charging protection of the battery.

Specifically, as shown in fig. 2, when the first controllable switch module 5 is turned on, the charging power supply may charge the battery, where the battery may be a lead-acid battery, and the charging power supply may be a charger or a dc power supply, and the application is not particularly limited herein; the voltage detection module 1 is used for judging whether the output end of the charging power supply is overvoltage or not, the current detection module 2 is used for judging whether the output end of the charging power supply is overcurrent or not, and then when the first controllable switch module 5 is turned off, 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 can firstly carry out charging 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 charging power supply to the battery; 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 over-voltage and/or the current detection module 2 determines that the output end of the charging power supply is over-current, it is described that the output of the charging power supply is abnormal at this time, the control module 4 will first 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 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, it is described that the output of the charging power supply is normal at this time, so that the control module 4 keeps controlling the first controllable switch module 5 to be turned on, and it is described that, 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 supply is over-voltage and/or the current detection module 2 determines that the output end of the charging power supply is over-current, the control module 4 will keep controlling the first controllable switch module 5 to switch off to stop charging the battery by the charging power supply.

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

The application provides an excessive pressure overflows charging protection device, compared with the prior art, this scheme is undulant at the critical point to charging source's output voltage, charging source damages to lead to its output voltage to take place to fluctuate by a wide margin and charging source's output current overflows three kinds of circumstances, under the prerequisite of having guaranteed the charging protection to the battery, handle and the outage time delay through foretell charging time delay, avoided the frequent switch-on and turn-off of first controllable switch module 5, strengthened this excessive pressure overflows charging protection device's practicality and stability.

On the basis of the above-described embodiment:

referring to fig. 3, fig. 3 is a schematic structural diagram of another over-voltage and over-current charging protection device provided by the present invention.

As a preferred embodiment, the current detection module 2 includes 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 the first comparator U1 is used for being turned on when the output end of the charging power supply is judged to be overcurrent according to the voltage at the two ends of the sampling resistor 3, and turned off when the output end of the charging power supply is judged not to be overcurrent according to the voltage at 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, the sampling resistor 3 is connected in series in a charging loop of the charging power supply for charging the battery, so that the current flowing through the sampling resistor 3 is the current at the output terminal of the charging power supply. The first comparator U1 is then used to collect the voltage across the sampling resistor 3 and determine whether the output of the charging power supply is over-current based on the voltage. Specifically, the judgment of whether the output end of the charging power supply is overcurrent or not can be realized according to the voltage at the two ends of the sampling resistor 3 and the first preset protection threshold of the first comparator U1, it should be noted that the first preset protection threshold here can be determined by reasonably selecting the type of the first comparator U1, and the overcurrent protection point of the output current of the charging power supply can be adjusted by adjusting the resistance value of the sampling resistor 3 in cooperation with the reasonable type selection of the first comparator U1.

It should be further noted that the first comparator U1 may be a controllable precision voltage regulator TL431, and the application is not limited herein.

It should be further noted that the current detection module 2 may further include a first filter capacitor C1 to implement filtering, one end of the first filter capacitor C1 is connected to the reference terminal 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 power supply in a simple and reliable manner for the subsequent actuation of the 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 a first resistor R1 is connected with the anode of the charging power supply, the anode of the battery and one end of a third resistor R3 respectively, the other end of the first resistor R1 is connected with one end of a second resistor R2 and the connected common end is connected with the reference end of a second comparator U2, the other end of the second resistor R2 is connected with the cathode of the charging power supply, the anode of a second comparator U2, the anode of a first voltage-stabilizing diode DZ1 and one end of a sampling resistor 3 respectively, the cathode of the second comparator U2 is connected with the other end of the third resistor R3 and the connected common end is connected with the cathode of the first voltage-stabilizing diode DZ1 and the control module 4 respectively;

the second comparator U2 is used for switching on when the output end of the charging power supply is judged to be overvoltage according to the voltage at two ends of the second resistor R2 and switching off when the output end of the charging power supply is judged to be not overvoltage according to the voltage at two ends of the second resistor R2; the first zener diode DZ1 is used to stabilize the voltage when the first comparator U1 and the second comparator U2 are both off, and is turned off when the second comparator U2 and/or the first comparator U1 are 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 at the output terminal of the charging power supply, and then the voltage collected by the second comparator U2 is the voltage across the second resistor R2, and determines whether the output terminal of the charging power supply is overvoltage or not according to the voltage, and the third resistor R3 is used for limiting the current. Specifically, as shown in fig. 3, when the output terminal of the charging power supply is not over-voltage, the second comparator U2 is turned off, and 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 divided voltage at the two ends of the second resistor R2 increases and is greater than the second preset protection threshold of the second comparator U2, the second comparator U2 is turned on to facilitate the subsequent operation of the control module 4, the voltage output by the voltage detection module 1 to the control module 4 is clamped at the on-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 judgment of whether the output end of the charging power supply is overvoltage or not 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, it should be noted that the second preset protection threshold here can be determined by reasonably selecting the type of the second comparator U2, and the overvoltage protection point of the output voltage of the charging power supply can be adjusted by adjusting the resistance value of the first resistor R1 and the resistance value of the second resistor R2 in cooperation with the reasonably selecting type of the second comparator U2.

It should be noted that the second comparator U2 may be a controllable precision voltage regulator TL431, and through a proper type selection of the first zener diode DZ1, the voltage across the second comparator U2 may be clamped when the second comparator U2 is not turned on, where the clamped voltage may be 36V, and the application is not limited herein.

It should be further noted that the voltage detection module 1 may further include a second filter capacitor C2 to implement filtering, one end of the second filter capacitor C2 is connected to the reference terminal 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 power supply in a simple and reliable manner for the subsequent actuation of the control module 4.

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

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

a second end of the first controllable switch Q1 is connected to the other end of the second resistor R2, and a control end of the first controllable switch Q1 is connected to a control end of the first controllable switch module 5, and is configured to be 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 switch is turned on when the output end of the charging power supply is judged to be overvoltage according to the voltage of the two ends of the second resistor R2, and is turned off when the output end of the charging power supply is judged to be not overvoltage according to the voltage of the two ends of the second resistor R2, and the switch comprises:

the charging circuit is turned on when the overvoltage of the output end of the charging power supply is judged according to the voltage of two ends of the equivalent resistor after the second resistor R2 and the fourth resistor R4 are connected in parallel, and is turned off when the overvoltage of the output end of the charging power supply is judged according to the voltage of two ends of the second resistor R2.

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 overvoltage or overcurrent, the first controllable switch module 5 is turned on to charge the battery by the charging power supply, and at this time, the first controllable switch Q1 is also turned on, 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 overvoltage according to the voltage across 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 overvoltage can be achieved according to the voltage across 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, it should be noted that the second preset protection threshold here can be determined by reasonably selecting the resistance of the second comparator U2, and the reasonably selecting the output voltage of the charging power supply by adjusting the resistance of the first resistor R1, the resistance of the second resistor R2, the resistance of the fourth resistor R4, and the second comparator U2 And pressing a protection point. Then, when the output end of the charging power supply is in overvoltage and not in overcurrent, the first controllable switch module 5 is still in a conducting state at this time, the second comparator U2 determines that the output end of the charging power supply is in overvoltage and is conducted 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 discharges firstly and controls the first controllable switch module 5 to turn off after the discharge is finished, at this time, the first controllable switch Q1 is also turned off, the fourth resistor R4 is switched out of the circuit, so that the second comparator U2 determines whether the output end of the charging power supply is no longer in overvoltage according to the voltage at two ends of the second resistor R2, which enables the voltage at two ends of the second resistor R2 to be reduced only when the output voltage of the charging power supply is reduced to a lower voltage value so as to turn off the second comparator U2, it should be noted that the adjustment of the voltage value which is reduced to a maximum when the charging is resumed can be achieved by adjusting the resistance value of the second resistor R2, the present application is not particularly limited herein. If the output end of the charging power supply is no longer overvoltage and overcurrent, the control module 4 will perform charging and control the first controllable switch module 5 to be turned on after the charging is finished so as to recover the charging of the charging power supply to the battery.

It should be noted that, the first controllable switch Q1 herein may be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a gate of the MOSFET serves as a control terminal of the first controllable switch Q1, a source of the MOSFET serves as a second terminal of the first controllable switch Q1, a drain of the MOSFET serves as a first terminal of the first controllable switch Q1, and the MOSFET may further include a body diode to discharge energy remaining when the MOSFET itself is turned off, which is not particularly limited herein.

Therefore, the reliable protection of the overvoltage condition of the output end of the charging power supply can be realized through the mode, the problem of battery charging protection of the output voltage of the charging power supply under the critical point fluctuation is solved better, the overvoltage protection is more stable, and the circuit is simple.

Referring to fig. 4, fig. 4 is a schematic structural diagram of another over-voltage and over-current 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 voltage stabilizing diode DZ2, and the other end of the fifth resistor R5 is connected with the first end of a second controllable switch Q2;

a 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 voltage stabilizing diode DZ1, the cathode of the light emitting diode is connected with the cathode of the second comparator U2, the collector of a phototriode of the optocoupler U3 is connected with the anode of the third voltage stabilizing 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 switched on when the second comparator U2 is switched on and being switched off when the second comparator U2 is switched off; the phototriode is used for conducting when the light emitting diode is conducted and shutting off when the light emitting diode is shut off;

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

a second end of the second controllable switch Q2 is connected to the other end of the first resistor R1 and the reference end of the second comparator U2, respectively, and a control end of the second controllable switch Q2 is connected to an anode of the second zener diode DZ2 and a cathode of the third zener diode DZ3, respectively, and is configured to be turned on when the phototransistor is turned on and turned off when the phototransistor is turned off.

In this embodiment, the inventor further aims at the condition that the output voltage of the charging power supply 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 optical coupler 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 overvoltage, 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 resistors for voltage sampling only include the first resistor R1 and the second resistor R2;

when the output end of the charging power supply is in overvoltage, 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, so that the fifth resistor R5 and the first resistor R1 are connected in parallel to participate in voltage sampling, and further, the voltage across the second resistor R2 is further increased, forming a positive feedback, so that the protection at the overvoltage critical point of the output voltage of the charging power supply is more stable, and more specifically, the judgment of whether the output terminal of the charging power supply 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, it should be noted that, the second predetermined protection threshold here may be determined by appropriate selection of the second comparator U2, the overvoltage protection point of the output 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 fifth resistor R5 in cooperation with the reasonable model selection of the second comparator U2; it should be noted that the adjustment of the voltage value which needs to be reduced to a maximum value when the charging is resumed can be realized by adjusting the resistance value of the fifth resistor R5, and the application is not particularly limited herein; the second voltage stabilizing diode DZ2 is used for stabilizing voltage to protect the second controllable switch Q2; the third voltage stabilizing diode DZ3 is used for stabilizing voltage to protect an optical coupler 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, 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 that when the optical coupler U3 is not turned on, the control terminal and the first terminal of the second controllable switch Q2 are pulled to an equal potential value to ensure that the second controllable switch Q2 is stably turned off; it should be further noted that, here, the second controllable switch Q2 may be a MOSFET, a gate of the MOSFET serves as a control terminal of the second controllable switch Q2, a source of the MOSFET serves as a first terminal of the second controllable switch Q2, a drain of the MOSFET serves as a second terminal of the second controllable switch Q2, and the MOSFET may further include a body diode to discharge energy remaining when the MOSFET itself is turned off, which is not particularly limited herein.

Therefore, by adding a voltage positive feedback, when the output end of the charging power supply is in overvoltage, the output voltage of the charging power supply needs to be reduced to a lower output voltage to recover 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 comprises a third controllable switch Q3 and a fourth zener diode DZ 4;

the control end of the third controllable switch Q3 is connected with the cathode of the fourth zener diode DZ4, and the connected common end 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, and the connected common end 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 serves as a control terminal of the third controllable switch Q3, a source of the MOSFET serves as a first terminal of the third controllable switch Q3, a drain of the MOSFET serves as a second terminal of the third controllable switch Q3, and the MOSFET may further include a body diode to discharge energy remaining when the MOSFET is turned off, which is not limited herein.

The fourth zener diode DZ4 can achieve voltage stabilization, and in order to further stabilize the gate-source voltage when the third controllable switch Q3 is turned on, the first controllable switch module 5 can 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;

a cathode of the first diode D1 is connected to a cathode of the first zener diode DZ1, a cathode of the first comparator U1, a first end of the sixth controllable switch Q6, and one end of the seventh resistor R7, respectively, and an anode of the first diode D1 is connected to a control end of the fourth controllable switch Q4, and is configured to be 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, and a common end of the seventh resistor R7 is connected with the first end of the fourth controllable switch Q4 and the cathode of the fifth zener diode DZ5, the other end of the capacitor E is 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, respectively, 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;

a second terminal of the fourth controllable switch Q4 is connected to the other terminal of the eighth resistor R8, and is 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 turn on when the charging of the capacitor E is finished, turn off when the discharging of the capacitor E is finished, and keep turning on when the first controllable switch Q1 turns on the first controllable switch module 5, the first comparator U1 turns off, and the second comparator U2 turns off;

a control terminal of the fifth controllable switch Q5 is connected to an anode of the fifth zener diode DZ5, and a first terminal of the fifth controllable switch Q5 is connected to a control terminal of the sixth controllable switch Q6, for turning on when the fifth zener diode DZ5 is turned on, and for turning off when the fifth zener diode DZ5 is turned off;

a control terminal of the sixth controllable switch Q6 is connected to the control terminal of the first controllable switch Q1 and the first controllable switch module 5, and is configured to be 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 this 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 terminal of the charging power supply is not over-voltage or 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. With the rise of the voltage at the two ends of the capacitor E, when the voltage at the two ends of the capacitor E is greater than the breakdown voltage of the fifth zener diode DZ5, the fifth zener diode DZ5 is turned on, so that the fifth controllable switch Q5 is turned on in a delayed manner, and further the sixth controllable switch Q6 is turned on in a delayed manner, so that the first controllable switch module 5 is controlled to be turned on in a delayed manner, and the delayed charging of the battery by the charging power supply is realized; it should be noted that, when the output terminal of the charging power supply is not over-voltage and not over-current all the time, the voltage of the cathode of the first diode D1 will be no less than the voltage of the anode of the capacitor E all the time, so the first diode D1 and the fourth controllable switch Q4 are always kept off.

When the first controllable switch module 5 is turned on and the output terminal of the charging power supply is over-voltage and/or over-current, please refer to fig. 4, which illustrates the control process by taking the case that the output terminal of the charging power supply is over-voltage and not over-current as an example: at the moment, the second comparator U2 is turned on, the light emitting diode of the optical coupler U3 is turned on, so that the first diode D1 is turned on, the fourth controllable switch Q4 is turned on, at the moment, the capacitor E forms a first discharge loop through the fourth controllable switch Q4 and the eighth resistor R8 to perform first discharge, then, the capacitor E also forms a second discharge loop through the first diode D1, the anode and the cathode of the light emitting diode of the optical coupler U3, the cathode and the anode of the second comparator U2, and the fourth resistor R4 to perform second discharge, finally, the voltage across the capacitor E is clamped to the sum of the conduction voltage drop of the light emitting diode of the optical coupler U3 and the conduction voltage drop of the cathode and the anode of the second comparator U2, at the moment, the discharge is finished, the clamping voltage across the capacitor E is smaller than the reverse breakdown voltage of the fifth voltage stabilizing diode DZ5 through the reasonable type selection of the fifth stabilizing diode DZ5, so that the fifth stabilizing diode DZ5 is turned off, and further, the fifth controllable switch Q5 and the sixth controllable switch Q6 are turned off in a delayed manner, and the first controllable switch module 5 is turned off, so that the delayed power-off of the charging power supply to the battery is realized.

It should be noted that, here, the fourth controllable switch Q4 may be a PNP transistor, a base of the PNP transistor serves as a control terminal of the fourth controllable switch Q4, an emitter of the PNP transistor serves as a first terminal of the fourth controllable switch Q4, and a collector of the PNP transistor serves as a second terminal of the fourth controllable switch Q4; the fifth controllable switch Q5 may be an NPN type triode, a base of the NPN type triode serves as a control terminal of the fifth controllable switch Q5, an emitter of the NPN type triode serves as a second terminal of the fifth controllable switch Q5, and a collector of the NPN type triode serves as a first terminal of the fifth controllable switch Q5, 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 to the base of the NPN type triode, and the other end of the seventeenth resistor R17 is connected to the emitter of the NPN type triode; the sixth controllable switch Q6 may be a PNP transistor, a base of the PNP transistor serves as a control terminal of the sixth controllable switch Q6, an emitter of the PNP transistor serves as a first terminal of the sixth controllable switch Q6, and a collector of the PNP transistor serves as a second terminal of the sixth controllable switch Q6, it should be noted that, in order to ensure stable conduction of the PNP transistor, 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 transistor, and the other end of the eighteenth resistor R18 is connected to the emitter of the PNP transistor, which is not limited herein.

It should be further noted that, the seventh resistor R7 herein has a larger resistance value, which can delay the charging time of the capacitor E, and the eighth resistor R8 herein has a smaller resistance value, which can realize the discharging of the capacitor E.

It can be seen that in this way, the control logic of the control module 4 can be stably and reliably implemented to implement the delay processing of charging and powering off the battery by the charging power supply.

As a preferred embodiment, the voltage regulator further comprises a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a sixth zener diode DZ 6;

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

switch on when judging charging source's output according to the voltage at sampling resistor 3 both ends and overflowing, turn off when judging charging source's output according to the voltage at sampling resistor 3 both ends and not overflowing, include:

the charging circuit is turned on when the output end of the charging power supply is judged to be overcurrent according to the sum of the voltage at the two ends of the sampling resistor 3 and the voltage at the two ends of the eleventh resistor R11, and is turned off when the output end of the charging power supply is judged not to be overcurrent according to the sum of the voltage at the two ends of the sampling resistor 3 and the voltage at 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 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 is overcurrent, thereby causing overcurrent protection failure; if the resistance value of the sampling resistor is selected to be too large, the voltage and the power consumption at two ends of the sampling resistor are large during normal charging, the charging of the lead-acid battery is influenced, and even the charging cannot be carried out. In order to solve the above technical problem, the overvoltage/overcurrent charging protection device in the present application may further include a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a sixth zener diode DZ 6.

Specifically, the ninth resistor R9 is used for current limiting, the sixth zener diode DZ6 can provide a stable voltage during operation, the tenth resistor R10 and the eleventh resistor R11 divide the stable voltage, so that when the first comparator U1 determines whether the output terminal of the charging power supply is overcurrent, the first comparator U1 determines according to the sum of the voltage across the sampling resistor 3 and the voltage across the eleventh resistor R11, so that the resistance value of the sampling resistor 3 can be selected to be a small value by reasonably selecting the resistance value of the tenth resistor R10, the resistance value of the eleventh resistor R11, and the magnitude of the stable voltage provided by the sixth zener diode DZ6, more specifically, the determination of whether the output terminal of the charging power supply is overcurrent can be achieved according to the sum of the voltage across the sampling resistor 3 and the voltage across the eleventh resistor R11 and the first preset protection threshold of the first comparator U1, it should be noted that the first preset protection threshold may be determined by reasonably selecting the type of the first comparator U1, and the overcurrent protection point for the output current of the charging power supply may be adjusted by adjusting the resistance value of the sampling resistor 3, the resistance value of the tenth resistor R10, the resistance value of the eleventh resistor R11, and the type selection of the sixth zener diode DZ6, in cooperation with the reasonably selecting the type of the first comparator U1.

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

Referring to fig. 5, fig. 5 is a schematic structural diagram of another over-voltage and over-current charging protection device provided by the present invention.

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

a reference terminal of the third comparator U4 is connected with the cathode of the third comparator U4, and a common terminal of the third comparator U4 is connected with one end of the twelfth resistor R12 and one end of the thirteenth resistor respectively, so as to provide a 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 connected with the other end of the sampling resistor 3 and the anode of the third comparator U4 respectively;

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

In this embodiment, the inventor provides another solution to the problem in the prior art that the resistance value of the sampling resistor 3 is difficult to determine, that is, the overvoltage and 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 current limiting, the third comparator U4 is connected in such a way that it can provide a stable voltage when it works, the thirteenth resistor R13 and the fourteenth resistor R14 divide the stable voltage, so that when the first comparator U1 determines whether the output end of the charging power supply is overcurrent, it determines according to the sum of the voltage at the two ends of the sampling resistor 3 and the voltage at the two ends of the fourteenth resistor R14, so that the resistance value of the sampling resistor 3 can be selected to be a smaller value by reasonably selecting the resistance value of the thirteenth resistor R13, the resistance value of the fourteenth resistor R14, and the magnitude of the stable voltage that the third comparator U4 can provide, more specifically, it can be determined whether the output end of the charging power supply is overcurrent according to the sum of the voltage at the two ends of the sampling resistor 3 and the voltage at the two ends of the fourteenth resistor R14 and the first preset protection threshold value of the first comparator U1, it should be noted that the first preset protection threshold may be determined by reasonably selecting the type of the first comparator U1, and the overcurrent protection point for the output current of the charging power supply may be adjusted by adjusting the resistance value of the sampling resistor 3, the resistance value of the thirteenth resistor R13, the resistance value of the fourteenth resistor R14, and the type selection of the third comparator U4, in cooperation with the reasonably selecting the type of the first comparator U1.

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

It should be noted that the third comparator U4 may be a controllable precision voltage regulator TL431, and the application is not limited herein.

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 sequentially connected.

For the introduction of the lead-acid battery charging circuit provided by the present invention, please refer to the above embodiment of the over-voltage and over-current charging protection device 6, and the present invention is not described herein again.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

It is further noted that, in the present 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. Also, 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 an … …" does not exclude the presence of other identical 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 over-voltage and over-current charging protection device according to claim 1, wherein the current detection module comprises a first comparator;

3. The over-voltage and over-current charging protection device according to 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 over-voltage and over-current charging protection device according to claim 3, wherein the voltage detection module further comprises a fourth resistor and a first controllable switch;

and the charging circuit is switched on when the output end of the charging power supply is judged to be overvoltage according to the voltages at the two ends of the equivalent resistor after the second resistor and the fourth resistor are connected in parallel, and is switched off when the output end of the charging power supply is judged to be not overvoltage according to the voltages at the two ends of the second resistor.

5. The over-voltage and over-current charging protection device according to claim 2, 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 over-voltage and over-current charging protection device according to any one of claims 2 to 5, wherein the first controllable switch module comprises a third controllable switch and a fourth zener diode;

7. The over-voltage and over-current charging protection device according to any one of claims 3 to 5, wherein 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;

8. The over-voltage and over-current charging 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 over-voltage and over-current charging 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 the overvoltage and overcurrent charging protection device as claimed in 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.