CN110661313B - Window voltage control storage battery discharge protection circuit based on discrete component - Google Patents

Abstract

The window voltage control battery discharge protection circuit based on discrete components proposed by the present invention includes a first input port, a second input port, an opening unit, an closing unit, and a control unit. The control unit is a MOS tube, the first input port, the second The input port is connected in parallel with the gate of the MOS transistor, and the first input port and the second input port are connected in parallel with the source of the MOS transistor. The opening unit includes a first transistor and a second transistor for setting the upper threshold voltage value. A voltage regulator tube, a first resistor, and a second resistor, the shutdown unit includes a second triode, a second voltage regulator tube for setting the lower threshold voltage value, and a third resistor. In the circuit of the present invention, only some commonly used The discrete components can build the control circuit, and the threshold control can be realized without writing a program, and the threshold can be adjusted, only need to replace the first voltage regulator tube and the second voltage regulator tube, to adapt to different scene requirements, cost Low cost, fast development speed, no maintenance program.

Description

A Window Voltage Control Battery Discharge Protection Circuit Based on Discrete Components

technical field

The invention relates to the technical field of battery protection, in particular to a window voltage control battery discharge protection circuit based on discrete components.

Background technique

The smart community monitoring equipment needs to be turned on by an external 15V mains power supply. The system is equipped with a 12V battery. When the external mains power supply is cut off, the battery can immediately take over the power supply. The voltage of the battery will continue to drop during the discharge process, especially when it is discharged with a large current, the voltage will drop sharply. When the battery stops discharging, the battery voltage will automatically rise. The level of the rebound voltage is related to the charge of the battery. Under certain conditions, after the battery is disconnected and discharged, the voltage returns to the level before discharge, but the battery power is already very low at this time, so repeated discharges will seriously damage the battery life. For this reason, we need a control circuit that is turned on when it is higher than 15V and turned off when it is lower than 12V. I have not found a corresponding control chip or a simple circuit in the relevant information. The existing method is to use a microcontroller or PLC to control the switching and timing of power on and off through programs, which brings inconvenience and burden to rapid development, increases the complexity and costs, and requires a separate maintenance program for power supply timing switching.

Contents of the invention

It is necessary to propose a window voltage control battery discharge protection circuit based on discrete components.

A window voltage control battery discharge protection circuit based on discrete components, including a first input port, a second input port, an opening unit, an closing unit, and a control unit, the control unit is a MOS tube, the first input port, the second input port After being connected in parallel, it is connected to the gate of the MOS tube, after the first input port and the second input port are connected in parallel, it is also connected to the source of the MOS tube, and the drain of the MOS tube is connected to the output port to be connected to the powered device. It includes a first triode, a first regulator for setting the upper threshold voltage, a first resistor, and a second resistor. The base of the first transistor is connected in series with the first regulator, and the first transistor The collector of the transistor is connected in series with the second resistor, the second resistor is connected in parallel with the gate of the MOS transistor and then connected in series with the first resistor, the first resistor and the base of the first triode are also connected in series with the first input port and the second input port , the shutdown unit includes a second triode, a second voltage regulator transistor for setting the lower threshold voltage value, and a third resistor. The base of the second transistor is connected in series with the second voltage regulator transistor, and the third resistor is connected to the first voltage regulator transistor. The collectors of the two transistors are connected in series, the third resistor is connected in parallel with the grid of the MOS transistor and then connected in series with the first resistor, and the base of the second transistor is connected with the drain of the MOS transistor.

Preferably, a backflow prevention diode is connected in series with the first input port, and a backflow prevention diode is connected in series with the second input port.

Preferably, a voltage regulator transistor is connected in series between the gate and the cathode of the MOS transistor as a protection loop.

Preferably, a diode and a capacitor are connected in parallel between the source and drain of the MOS transistor.

In the circuit of the present invention, only some commonly used discrete components are needed to build a control circuit, and the threshold control can be realized without writing a program, and the threshold can be adjusted, and only two of the first regulator tube and the second regulator tube need to be replaced. Devices, adapt to different scene requirements, low cost, fast development speed, no maintenance program.

Description of drawings

Fig. 1 is the circuit diagram of the present invention.

Detailed ways

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. Ordinary technicians can also obtain other drawings based on these drawings on the premise of not paying creative work.

Referring to Fig. 1, an embodiment of the present invention provides a window voltage control battery discharge protection circuit based on discrete components, including a first input port, a second input port, an opening unit, an closing unit, and a control unit. The control unit is a MOS tube , the first input port and the second input port are connected in parallel to the gate of the MOS transistor, the first input port and the second input port are connected in parallel to the source of the MOS transistor, and the drain of the MOS transistor is connected to the output port to Connected to the powered device, the opening unit includes a first triode, a first regulator tube for setting the upper threshold voltage value, a first resistor, a second resistor, the base of the first triode is connected to the first Zener tubes are connected in series, the collector of the first triode is connected in series with the second resistor, the second resistor is connected in parallel with the grid of the MOS transistor and then connected in series with the first resistor, the base of the first resistor and the first triode are also connected with The first input port and the second input port are connected in series, and the shut-off unit includes a second transistor, a second voltage regulator transistor for setting the lower threshold voltage value, and a third resistor, and the base of the second transistor is connected to the second Zener tubes are connected in series, the third resistor is connected in series with the collector of the second triode, the third resistor is connected in parallel with the grid of the MOS tube and then connected in series with the first resistor, the base of the second triode is connected to the drain of the MOS tube connect.

In the present invention, when two inputs exist at the same time, the input with higher voltage supplies power to subsequent equipment. The turn-on unit realizes the judgment of the turn-on voltage, uses the regulated voltage value of the first Zener diode D4 to set the threshold, and controls the gate voltage of Q1 through the switching action of the first triode Q2. The shutdown unit realizes the judgment of the power-off voltage, uses the regulated value of the second Zener diode D5 to set the power-off threshold, and controls the gate voltage of Q1 through the switching function of the second triode Q3. The control unit realizes the on-off control of the power supply of the equipment. When the voltage of the gate of Q1 is equal to the voltage of the source, Q1 is disconnected and no current flows between the source and the drain. When the voltage of the gate of Q1 is lower than the voltage of the source, Q1 conducts the current From source to drain, the output supplies power to the device.

Further, a reverse flow prevention diode is connected in series with the first input port, and a reverse flow prevention diode is connected in series with the second input port.

Further, a voltage regulator tube is connected in series between the gate and the cathode of the MOS tube as a protection circuit.

Further, a diode and a capacitor are connected in parallel between the source and drain of the MOS tube. So as to play the role of freewheeling and buffering the MOS tube.

The working process of using the circuit of the present invention to control battery overdischarge is as follows:

The first input port is VIN1, and the second input port is VIN2. It is assumed that VIN1 is connected to an external AC-to-DC 15V DC power supply, and VIN2 is connected to a 12V battery. Set the opening threshold V1=15V for the external device to work, and the shutdown threshold V2=11V for the device to stop working. This circuit can turn on the device with a voltage higher than 15V, turn off the device with a voltage lower than 12V, and connect the 12V battery separately. It cannot be turned on, because the battery discharge is prohibited when the device is not in use. If the device needs to be turned from the off state to the working state, it must be turned on by a voltage higher than 15V. After turning on, the voltage above 12V can work normally.

A specific embodiment is given as an example below:

VIN1=15V, VIN2=12V, D4 voltage regulator is used to set the upper threshold V1=14V, D5 voltage regulator is used to set the lower threshold V2=11V.

VIN1 is greater than V1 +0.7V, Q2 is turned on, VIN1 flows through the first resistor R1 and the second resistor R2, and is divided by the first resistor R1 and the second resistor R2, and the gate voltage of Q1 decreases, which is lower than the source voltage VIN1 , Q1 is turned on, VIN1 flows from the source of Q1 to the drain, at this time VIN1=15V is greater than V2, Q3 is turned on, the current flows through the first resistor R1, the second resistor R2, the third resistor R3 and divides the voltage to Q1 gate, Q1 continues to conduct.

When VIN1 disappears, it is powered by VIN2 of the 12V battery. At this time, VIN2 is less than V1, transistor Q2 is turned off, VIN2 is greater than V2, transistor Q3 continues to conduct, and Q1 keeps on and continues to output. When the battery voltage VIN2 gradually decreases to VIN2 less than V2+0.7 When V, Q3 is cut off. At this time, there is no current flowing through the second resistor R2 and the third resistor R3. The gate voltage of Q1 rises to a high voltage, which is the same as the source voltage VIN2. Q1 is cut off, and there is no current between the source and the drain. Current flows and the VOUT output is zero.

When VIN1 is greater than V1+0.7V, the system will be powered on again.

If the values of the first Zener diode D4 and the second D5 are adjusted, applications such as 24V battery protection and 36V battery protection can be realized, and it can also be used in the protection application of photovoltaic industry batteries.

This system realizes that the input voltage is higher than V1 to turn on the power supply of the device. After the device is turned on, the input voltage is greater than V2 (V1>V2) and the device is normally powered. V1 and V2 are adjustable, and the corresponding parameters can be determined according to different usage requirements. For example, V1 selects 28V and V2 selects 24V, which can be used to protect the application of 24V batteries and prolong the service life of batteries.

The modules or units in the device of the embodiment of the present invention can be combined, divided and deleted according to actual needs.

What is disclosed above is only a preferred embodiment of the present invention, and certainly cannot limit the scope of rights of the present invention with this. Those of ordinary skill in the art can understand the whole or part of the process of realizing the above-mentioned embodiment, and make according to the claims of the present invention The equivalent changes still belong to the scope covered by the invention.

Claims (4)

1. A window voltage control battery discharge protection circuit based on discrete components, characterized in that: it includes a first input port, a second input port, an opening unit, a closing unit, and a control unit, and the first input port is used to communicate with the outside world A power supply connection, the second input port is used to connect with the second external power supply, the control unit is a MOS tube, the first input port and the second input port are connected in parallel with the gate of the MOS tube, the first input port, the second input port After the port is connected in parallel, it is also connected to the source of the MOS tube, and the drain of the MOS tube is connected to the output port to be connected to the powered device. A voltage tube, a first resistor, a second resistor, the base of the first triode is connected in series with the first regulator tube, the collector of the first triode is connected in series with the second resistor, and the second resistor is connected with the gate of the MOS tube After being connected in parallel, it is connected in series with the first resistor, and the first resistor and the base of the first transistor are also connected in series with the first input port and the second input port. The shutdown unit includes a second transistor for setting the lower threshold voltage value The second voltage regulator tube and the third resistor, the base of the second transistor is connected in series with the second voltage regulator tube, the third resistor is connected in series with the collector of the second transistor, the third resistor is connected with the gate of the MOS tube After being connected in parallel, it is connected in series with the first resistor, and the base of the second triode is connected with the drain of the MOS transistor. 2. The window voltage control battery discharge protection circuit based on discrete components as claimed in claim 1, characterized in that: a diode for preventing backflow is connected in series with the first input port, and a diode for preventing backflow is connected in series with the second input port. diode. 3. The window voltage control battery discharge protection circuit based on discrete components as claimed in claim 1, characterized in that: a voltage regulator tube is connected in series between the grid and the negative pole of the MOS tube as a protection circuit. 4. The window voltage control battery discharge protection circuit based on discrete components as claimed in claim 1, characterized in that a diode and a capacitor are connected in parallel between the source and drain of the MOS transistor.

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