Battery over-discharge protection circuit

Abstract

The utility model discloses a battery over-discharge protection circuit, which relates to the technical field of battery protection and comprises a power supply input end, a power supply output end, a battery electric quantity detection circuit, a threshold judgment unit, a delay protection circuit and a power connection switch. The over-discharge degree of the battery is judged according to the preset first voltage threshold value and the preset second voltage threshold value, when the voltage of the battery is lower than the preset second voltage threshold value, the time-delay protection circuit is controlled to be connected into the main circuit, and when the voltage of the battery is not lower than the preset second voltage threshold value, the time-delay protection circuit and the main circuit are controlled to be in an open-circuit state. When the voltage of the battery is lower than a preset second voltage threshold value, the power connection switch is controlled to be switched off, when the voltage of the battery is not lower than the preset second voltage threshold value, the power connection switch is controlled to be switched on, battery over-discharge protection is achieved through the combined action of the delay protection circuit and the power connection switch, and the effects of reducing the cost and reducing the failure rate are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery protection, in particular to a battery over-discharge protection circuit. Background Art

[0002] Over discharge refers to the behavior of a battery continuing to discharge after releasing its internal charge. Over discharge of a battery may cause irreversible consequences to the battery. If over discharge increases the internal pressure of the battery, the capacity of the battery will be greatly attenuated. The discharge cut-off voltage is usually determined according to the discharge current. Over discharge of a battery may bring catastrophic consequences to the battery, especially over discharge with high current, or repeated over discharge will have a greater impact on the battery.

[0003] Generally speaking, overdischarge will increase the internal pressure of the battery, and the reversibility of the positive and negative active materials will be impaired. Even if the charge is only partially restored, the capacity will be greatly reduced. With the increase in the penetration rate of handheld devices, the demand for charging multi-cell lithium or sodium batteries has increased year by year, especially in the fields of power tools, sweepers, vacuum cleaners, floor scrubbers, etc. Taking ternary lithium batteries as an example, their overvoltage point is around 4.25V and the undervoltage point is around 2.5-2.7V, so for the charger, the output constant current range is required to be around 58% of the constant voltage point. However, users often consider that normal charging can be performed under the premise that the battery has a certain amount of overdischarge, so the actual required undervoltage point may be around 2.0V-2.3V. At this time, the required charger constant current range is as low as 40%-50% of the constant voltage point.

[0004] Therefore, how to ensure a battery over-discharge protection circuit with reasonable structure, good stability and high safety is an urgent problem to be solved by technicians in this field. Utility Model Content

[0005] The utility model provides a battery over-discharge protection circuit, which has the advantage of improving battery stability, so as to solve the problem that over-discharge will increase the internal pressure of the battery, thereby greatly attenuating the capacity of the battery.

[0006] In order to achieve the purpose of improving battery stability, the utility model provides the following technical solutions: a battery over-discharge protection circuit, which is connected in series between the battery and the power supply branch of the electronic system, comprises a power input terminal, a power output terminal, a battery power detection circuit, a threshold judgment unit, a delay protection circuit and a power switch;

[0007] The first end of the battery power detection circuit is connected to the power input end, the second end of the battery power detection circuit is connected to the power output end, the battery power detection circuit is used to sample the power of the battery, and the second end is grounded through a first resistor R16;

[0008] The threshold judgment unit judges that the voltage of the battery is lower than a preset first voltage threshold, generates a first control signal and sends it to the control module delay protection circuit;

[0009] When the voltage of the battery is lower than a preset second voltage threshold, the delay protection circuit is controlled to be connected to the main circuit; when the voltage of the battery is not lower than the preset second voltage threshold, the delay protection circuit and the main circuit are controlled to be in an open circuit state;

[0010] The threshold judgment unit judges that the voltage of the battery is lower than a preset second voltage threshold, generates a second control signal and sends it to the control module.

[0011] When the voltage of the battery is lower than a preset second voltage threshold, the power switch is controlled to be turned off, and when the voltage of the battery is not lower than the preset second voltage threshold, the power switch is controlled to be turned on.

[0012] As a preferred technical solution of the present utility model, the battery power detection circuit includes a rectifier diode, which is connected in parallel with a first resistor R15, which is connected in series with a first resistor R13, which is connected in parallel with a first resistor R14, which is coupled with a first resistor R14, and which is coupled with a power switch through a capacitor C33.

[0013] As a preferred technical solution of the present utility model, the threshold judgment unit is connected in parallel with the third resistor R31, and the third resistor R31 is connected in series with the second resistor R21.

[0014] As a preferred technical solution of the utility model, the control module is used to control the extension circuit to access the main circuit and control the power switch to cut off the power.

[0015] As a preferred technical solution of the present utility model, the first resistor R11, the first resistor R12, the first resistor R13, the first resistor R14, the first resistor R15 and the first resistor R16 are all pull-up resistors.

[0016] As a preferred technical solution of the present utility model, the second resistor R21 and the second resistor R22 are current limiting resistors.

[0017] As a preferred technical solution of the present utility model, the third resistor R31 and the third resistor R32 are anti-interference resistors.

[0018] Compared with the prior art, the utility model provides a battery over-discharge protection circuit, which has the following beneficial effects: the battery over-discharge protection circuit judges the battery over-discharge degree according to a preset first voltage threshold and a second voltage threshold; when the battery voltage is lower than the preset second voltage threshold, the time delay protection circuit is controlled to be connected to the main circuit; when the battery voltage is not lower than the preset second voltage threshold, the time delay protection circuit and the main circuit are controlled to be in an open circuit state; when the battery voltage is lower than the preset second voltage threshold, the power switch is controlled to be turned off; when the battery voltage is not lower than the preset second voltage threshold, the power switch is controlled to be turned on; the battery over-discharge protection is realized by the joint action of the time delay protection circuit and the power switch, thereby achieving the effect of reducing costs and reducing failure rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the circuit connection structure of the utility model. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] See also Figure 1 The utility model discloses a battery over-discharge protection circuit, which is connected in series between a battery and a power supply branch of an electronic system, and comprises a power input terminal, a power output terminal, a battery power detection circuit, a threshold judgment unit, a delay protection circuit and a power switch;

[0022] A first end of the battery power detection circuit is connected to the power input end, a second end of the battery power detection circuit is connected to the power output end, the battery power detection circuit is used to sample the battery power, and the second end is grounded through a first resistor R16;

[0023] The threshold judgment unit judges that the voltage of the battery is lower than a preset first voltage threshold, generates a first control signal and sends it to the control module delay protection circuit;

[0024] When the voltage of the battery is lower than the preset second voltage threshold, the control delay protection circuit is connected to the main circuit, and when the voltage of the battery is not lower than the preset second voltage threshold, the control delay protection circuit and the main circuit are in an open circuit state;

[0025] The threshold determination unit determines that the voltage of the battery is lower than a preset second voltage threshold, generates a second control signal and sends it to the control module.

[0026] When the voltage of the battery is lower than the preset second voltage threshold, the power switch is controlled to be turned off, and when the voltage of the battery is not lower than the preset second voltage threshold, the power switch is controlled to be turned on.

[0027] Specifically, the battery power detection circuit includes a rectifier diode, which is connected in parallel with the first resistor R15, the first resistor R15 is connected in series with the first resistor R13, the first resistor R13 is connected in parallel with the first resistor R14, the first resistor 14 is coupled with the first resistor R16, and the first resistor R14 is coupled with the power switch through the capacitor C33.

[0028] Specifically, the threshold determination unit is connected in parallel with the third resistor R31, and the third resistor R31 is connected in series with the second resistor R21.

[0029] Specifically, the control module is used to control the extension circuit to access the main circuit and control the power switch to cut off the power.

[0030] Specifically, the first resistor R11 , the first resistor R12 , the first resistor R13 , the first resistor R14 , the first resistor R15 , and the first resistor R16 are all pull-up resistors.

[0031] Specifically, the second resistor R21 and the second resistor R22 are current limiting resistors.

[0032] Specifically, the third resistor R31 and the third resistor R32 are anti-interference resistors.

[0033] The working principle and use process of the utility model are as follows: the over-discharge degree of the battery is judged according to the preset first voltage threshold and the second voltage threshold. When the voltage of the battery is lower than the preset second voltage threshold, the control delay protection circuit is connected to the main circuit. When the voltage of the battery is not lower than the preset second voltage threshold, the control delay protection circuit and the main circuit are in an open circuit state;

[0034] When the battery voltage is lower than the preset second voltage threshold, the power switch is controlled to be turned off. When the battery voltage is not lower than the preset second voltage threshold, the power switch is controlled to be turned on. The battery over-discharge protection is achieved through the cooperation of the delay protection circuit and the power switch.

[0035] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A battery over-discharge protection circuit, connected in series between the battery and the power supply branch of the electronic system, characterized in that: It includes a power input terminal, a power output terminal, a battery power detection circuit, a threshold judgment unit, a delay protection circuit and a power switch; The first end of the battery power detection circuit is connected to the power input end, the second end of the battery power detection circuit is connected to the power output end, the battery power detection circuit is used to sample the power of the battery, and the second end is grounded through a first resistor R16; The threshold judgment unit judges that the voltage of the battery is lower than a preset first voltage threshold, generates a first control signal and sends it to the control module delay protection circuit; The threshold judgment unit judges that the voltage of the battery is lower than a preset second voltage threshold, generates a second control signal and sends it to the control module.

2. A battery over-discharge protection circuit according to claim 1, characterized in that: The battery power detection circuit includes a rectifier diode, which is connected in parallel with a first resistor R15, which is connected in series with a first resistor R13, which is connected in parallel with a first resistor R14, which is coupled with a first resistor R16, and which is coupled with a power switch via a capacitor C33.

3. A battery over-discharge protection circuit according to claim 2, characterized in that: The threshold determination unit is connected in parallel with the third resistor R31, and the third resistor R31 is connected in series with the second resistor R21.

4. A battery over-discharge protection circuit according to claim 2, characterized in that: The control module is used to control the extension circuit to access the main circuit and control the power switch to cut off the power.

5. The battery over-discharge protection circuit according to claim 1, characterized in that: The first resistor R11 , the first resistor R12 , the first resistor R13 , the first resistor R14 , the first resistor R15 and the first resistor R16 are all pull-up resistors.

6. A battery over-discharge protection circuit according to claim 3, characterized in that: The second resistor R21 and the second resistor R22 are current limiting resistors.

7. A battery over-discharge protection circuit according to claim 3, characterized in that: The third resistor R31 and the third resistor R32 are anti-interference resistors.

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