Battery power supply output protection circuit

Abstract

The utility model discloses a battery power supply output protection circuit, which can realize output current-limiting protection and turn-off self-locking functions, and realizes the detection of a current-limiting signal of a voltage signal of a current sampling resistor through a signal amplification and voltage comparison circuit consisting of a first operational amplifier, a second operational amplifier, a corresponding resistor and a stabilizing diode. A current limiting signal realizes on-off and self-locking of power supply output through a self-locking switch circuit composed of a first triode, a fourth triode, a relay and corresponding resistors and capacitors, and alarms through an alarm circuit composed of a third triode and a buzzer. A charge discharge circuit composed of a second triode, a fifth triode, a second diode, a third electrolytic capacitor, a seventh resistor and a tenth resistor performs charge discharge on a filter capacitor of the voltage conversion chip. According to the utility model, current-limiting protection of any current can be effectively realized, and rapid discharge can be realized when the power supply is shut down, so that continuous back-and-forth switching of power supply output in two states of closing and opening is avoided, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of power supply current limiting protection, and more specifically to a battery output current limiting protection and shutdown self-locking circuit. Background Art

[0002] When a battery is used as a power supply, an excessive output current may cause battery failure and, in severe cases, accidents such as fires. Therefore, current limiting protection is very important. In a common overcurrent protection circuit, the output is turned off when overcurrent occurs. Since the circuit is in a non-overcurrent state when the output is turned off, the power supply output is automatically turned on again, causing the power supply output to continuously switch between the off and on states, resulting in circuit instability and damaging the circuit and equipment. Although an overcurrent protection circuit with a self-locking function can solve this problem, it can only achieve overcurrent protection when the current suddenly increases infinitely, and it is impossible to set the current limiting protection for any current magnitude. In addition, in the existing solutions, due to the presence of filter capacitors in the output power supply, there is a fluctuating state of continuous shutdown and startup during overcurrent protection action, and the reliability is not high. Utility Model Content

[0003] The purpose of the present invention is to propose a current limiting protection and shutdown self-locking circuit for the above-mentioned existing technical problems, which can set the magnitude of the current limiting protection while ensuring high reliability.

[0004] To achieve the above object, the present utility model adopts the following technical solutions:

[0005] A battery power output protection circuit includes a current sampling resistor, a first resistor to an eleventh resistor, a first capacitor, a second capacitor, a third electrolytic capacitor, a first operational amplifier, a second operational amplifier, a first transistor to a fifth transistor, a first diode, a second diode, a first zener diode, a buzzer, a relay, a voltage conversion chip, and a fourth electrolytic capacitor.

[0006] The output terminal of the battery power supply is connected to the input terminal of the voltage conversion chip. The output terminal of the voltage conversion chip is connected to one end of the first resistor, the fifth resistor, and the current sampling resistor, and is connected to the positive electrode of the fourth electrolytic capacitor. The negative electrode of the fourth electrolytic capacitor is grounded. The other end of the current sampling resistor is connected to one end of the second resistor and the operating side of the relay. The other end of the first resistor is connected to one end of the third resistor and the positive input terminal of the first operational amplifier. The other end of the third resistor is grounded. The other end of the second resistor is connected to one end of the sixth resistor and the negative input of the first operational amplifier. The output terminal of the first operational amplifier is connected to the other end of the sixth resistor and the positive input terminal of the second operational amplifier. The power supply pin of the first operational amplifier is connected to the working voltage, and the ground pin of the first operational amplifier is connected to the working ground. The negative input terminal of the second operational amplifier is connected to the eighth resistor and the negative electrode of the first zener diode. The other end of the eighth resistor is connected to the working voltage, and the positive electrode of the first zener diode is connected to the working ground. The output terminal of the second operational amplifier is connected to the collector of the first triode, the base of the fourth triode, the ninth resistor, and one end of the second capacitor. The ninth resistor and the other end of the second capacitor are grounded. The emitter of the first triode is connected to the positive pole of the first diode, the fourth resistor, the first capacitor, and one end of the control side of the relay. The other end of the control side of the relay is connected to the working voltage and the negative pole of the first diode. The base of the first triode is connected to the collector of the fourth triode, one end of the eleventh resistor, and the other end of the fourth resistor and the first capacitor. The emitter of the fourth triode is grounded. The other end of the eleventh resistor is connected to the base of the third triode. The emitter of the third triode is connected to the negative pole of the buzzer, and the positive pole of the buzzer is connected to the working voltage. The collector of the third triode is grounded;

[0007] The other end of the fifth resistor is connected to the collector of the fifth triode. The emitter of the fifth triode is grounded. The base of the fifth triode is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to the collector of the second triode. The base of the second triode is connected to one end of the seventh resistor. The other end of the seventh resistor is connected to the output terminal of the battery power supply. The emitter of the second triode is connected to the positive extreme of the third electrolytic capacitor, the negative electrode of the second diode. The positive electrode of the second diode is connected to the output terminal of the battery power supply. The negative extreme of the third electrolytic capacitor is grounded.

[0008] Furthermore, the first triode, the second triode, and the third triode are PNP triodes, the fourth triode and the fifth triode are NPN triodes, and the first operational amplifier and the second operational amplifier are two operational amplifier units in the same operational amplifier chip.

[0009] The beneficial effects of the present utility model are as follows: It can set the current limit protection of the current size arbitrarily, overcome the disadvantage that the traditional overcurrent protection can only perform overcurrent protection when the current suddenly increases infinitely, and is suitable for a wider range of scenarios. At the same time, it can reliably and effectively prevent the circuit from being in an unstable state of repeated protection and activation, and realizes an effective current limit protection function. Description of the Drawings

[0010] Appendix Figure 1 It is a circuit diagram for protecting the output of a battery power supply. Specific Embodiments

[0011] The present utility model will be further described below in conjunction with the description of the drawings and embodiments:

[0012] As Figure 1 shown, a battery power output protection circuit includes a current sampling resistor Rs, a first resistor to an eleventh resistor (R1~R11), a first capacitor, a second capacitor (C1, C2), a third electrolytic capacitor C3, a first operational amplifier, a second operational amplifier (U1A, U1B), a first transistor to a fifth transistor (Q1~Q5), a first diode, a second diode (D1, D2), a first voltage regulator diode Z1, a buzzer MK1, a relay K1, a voltage conversion chip U2, and a fourth electrolytic capacitor C4.

[0013] The output terminal Vin of the battery power supply is connected to the input terminal of the voltage conversion chip U2. The output terminal of the voltage conversion chip U2 is connected to one end of the first resistor R1, the fifth resistor R5, and the current sampling resistor Rs, and is connected to the positive electrode of the fourth electrolytic capacitor C4. The negative electrode of the fourth electrolytic capacitor C4 is grounded. The other end of the current sampling resistor Rs is connected to one end of the second resistor R2 and the operating side of the relay K1. The other end of the first resistor R1 is connected to one end of the third resistor R3 and the positive input terminal of the first operational amplifier U1A. The other end of the third resistor R3 is grounded. The other end of the second resistor R2 is connected to one end of the sixth resistor R6 and the negative input of the first operational amplifier U1A. The output terminal of the first operational amplifier U1A is connected to the other end of the sixth resistor R6 and the positive input terminal of the second operational amplifier U1B. The power supply pin of the first operational amplifier U1A is connected to the operating voltage VCC, and the ground pin of the first operational amplifier U1A is connected to the operating ground. The negative input terminal of the second operational amplifier U1B is connected to the eighth resistor R8 and the negative electrode of the first zener diode Z1. The other end of the eighth resistor R8 is connected to the operating voltage VCC, and the positive electrode of the first zener diode Z1 is connected to the operating ground. The output terminal of the second operational amplifier U1B is connected to the collector of the first transistor Q1, the base of the fourth transistor Q4, one end of the ninth resistor R9, and one end of the second capacitor C2. The other ends of the ninth resistor R9 and the second capacitor C2 are grounded. The emitter of the first transistor Q1 is connected to the positive electrode of the first diode D1, the fourth resistor R4, one end of the first capacitor C1, and one end of the control side of the relay K1. The other end of the control side of the relay K1 is connected to the operating voltage VCC and the negative electrode of the first diode D1. The base of the first transistor Q1 is connected to the collector of the fourth transistor Q4, one end of the eleventh resistor R11, and the other ends of the fourth resistor R4 and the first capacitor C1. The emitter of the fourth transistor Q4 is grounded. The other end of the eleventh resistor R11 is connected to the base of the third transistor Q3. The emitter of the third transistor Q3 is connected to the negative electrode of the buzzer MK1. The positive electrode of the buzzer MK1 is connected to the operating voltage VCC. The collector of the third transistor Q3 is grounded;

[0014] The other end of the fifth resistor R5 is connected to the collector of the fifth transistor Q5. The emitter of the fifth transistor Q5 is grounded. The base of the fifth transistor Q5 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is connected to the collector of the second transistor Q2. The base of the second transistor Q2 is connected to one end of the seventh resistor R7. The other end of the seventh resistor R7 is connected to the output terminal Vin of the battery power supply. The emitter of the second transistor Q2 is connected to the positive terminal of the third electrolytic capacitor C3, the negative electrode of the second diode D2, the positive electrode of the second diode D2 is connected to the output terminal Vin of the battery power supply, and the negative terminal of the third electrolytic capacitor C3 is grounded.

[0015] Further, the first triode Q1, the second triode Q2, and the third triode Q3 are PNP triodes, the fourth triode Q4 and the fifth triode Q5 are NPN triodes, and the first operational amplifier and the second operational amplifier are two operational amplifier units in the same operational amplifier chip.

[0016] In the working state, the operating side of the relay K1 is in the normally closed state. After the output terminal Vin of the battery power supply is converted by the voltage conversion chip U2, it passes through the current sampling resistor Rs, and the required power supply voltage is output from the output voltage terminal Vout of the operating side of the relay K1.

[0017] The voltage across the current sampling resistor Rs is amplified by an amplifier circuit composed of the first resistor R1, the second resistor R2, the third resistor R3, the sixth resistor R6, and the first operational amplifier U1A, and then compared with the reference voltage at the negative input terminal of the second operational amplifier U1B. In the normal state, the second operational amplifier U1B outputs a low level, the fourth triode Q4 is cut off, the base of the third triode Q3 is at a high level, and the buzzer MK1 does not alarm; when the current through the current sampling resistor Rs is too large, the second operational amplifier U1B outputs a high level, the first triode Q1 and the fourth triode Q4 conduct, the control side of the relay K1 is attracted, the operating side of the relay K1 is in the off state, the output terminal Vin of the battery power supply and the output voltage terminal Vout are disconnected, the base of the third triode Q3 is at a low level, the third triode Q3 conducts, and the buzzer MK1 alarms. At this time, the current through the current sampling resistor Rs disappears, the second operational amplifier U1B outputs a low level, but the first triode Q1 has conducted, the base of the third triode Q3 is at a low level, and the buzzer MK1 remains in the alarm state, thus realizing the self-locking function. The current magnitude threshold for overcurrent action in the circuit is adjusted by the first voltage stabilizing diode Z1 and the resistance value of the eighth resistor R8. By changing the resistance values of the first voltage stabilizing diode Z1 and the eighth resistor R8 with different voltage stabilizing parameter models to adjust the reference voltage at the negative input terminal of the second operational amplifier U1B, the adjustment of the current magnitude threshold can be achieved.

[0018] The output end of the voltage conversion chip U2 has a large-capacity fourth electrolytic capacitor C4 for filtering, and the current limiting protection circuit is prone to malfunction when the power is turned off and powered on after self-locking. For this reason, a fast capacitor charge discharge circuit is formed by the fifth resistor R5, the fifth triode Q5, the tenth resistor R10, the second triode Q2, the seventh resistor R7, the third electrolytic capacitor C3 and the second diode D2 to prevent malfunction. When powered on, the output end Vin of the battery power supply charges the third electrolytic capacitor C3 through the second diode D2, the base and emitter of the second triode Q2 are at a high level, the second triode Q2 cannot be turned on, and the fifth triode Q5 is turned off. When the power is off, the third electrolytic capacitor C3 discharges through the second triode Q2, the fifth triode Q5 is turned on, and the charge of the fourth electrolytic capacitor C4 connected to the output end of the voltage conversion chip U2 is quickly released, thereby avoiding malfunction of the current limiting protection circuit when the power is turned off and powered on after self-locking.

[0019] In addition to being used for battery power supplies, the utility model can also be applied to current limiting protection and shutdown self-locking of various common power supplies.

[0020] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A battery power output protection circuit, characterized in that: It includes a current sampling resistor, the first to the eleventh resistors, the first capacitor, the second capacitor, the third electrolytic capacitor, the first operational amplifier, the second operational amplifier, the first to the fifth triodes, the first diode, the second diode, the first zener diode, a buzzer, a relay, a voltage conversion chip, and the fourth electrolytic capacitor; The output terminal of the battery power supply is connected to the input terminal of the voltage conversion chip. The output terminal of the voltage conversion chip is connected to one end of the first resistor, the fifth resistor, and the current sampling resistor, and is also connected to the positive electrode of the fourth electrolytic capacitor. The negative electrode of the fourth electrolytic capacitor is grounded. The other end of the current sampling resistor is connected to one end of the second resistor and the operating side of the relay. The other end of the first resistor is connected to one end of the third resistor and the positive input terminal of the first operational amplifier. The other end of the third resistor is grounded. The other end of the second resistor is connected to one end of the sixth resistor and the negative input of the first operational amplifier. The output terminal of the first operational amplifier is connected to the other end of the sixth resistor and the positive input terminal of the second operational amplifier. The power supply pin of the first operational amplifier is connected to the working voltage, and the ground pin of the first operational amplifier is connected to the working ground. The negative input terminal of the second operational amplifier is connected to the eighth resistor and the negative electrode of the first zener diode. The other end of the eighth resistor is connected to the working voltage, and the positive electrode of the first zener diode is connected to the working ground. The output terminal of the second operational amplifier is connected to the collector of the first triode, the base of the fourth triode, the ninth resistor, and one end of the second capacitor. The ninth resistor and the other end of the second capacitor are grounded. The emitter of the first triode is connected to the positive electrode of the first diode, the fourth resistor, the first capacitor, and one end of the control side of the relay. The other end of the control side of the relay is connected to the working voltage and the negative electrode of the first diode. The base of the first triode is connected to the collector of the fourth triode, one end of the eleventh resistor, and is also connected to the other end of the fourth resistor and the first capacitor. The emitter of the fourth triode is grounded. The other end of the eleventh resistor is connected to the base of the third triode. The emitter of the third triode is connected to the negative electrode of the buzzer, and the positive electrode of the buzzer is connected to the working voltage. The collector of the third triode is grounded; The other end of the fifth resistor is connected to the collector of the fifth triode. The emitter of the fifth triode is grounded. The base of the fifth triode is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to the collector of the second triode. The base of the second triode is connected to one end of the seventh resistor. The other end of the seventh resistor is connected to the output terminal of the battery power supply. The emitter of the second triode is connected to the positive extreme of the third electrolytic capacitor, the negative electrode of the second diode. The positive electrode of the second diode is connected to the output terminal of the battery power supply. The negative extreme of the third electrolytic capacitor is grounded.

2. The battery power output protection circuit according to claim 1, wherein: The first triode, the second triode, and the third triode are PNP triodes. The fourth triode and the fifth triode are NPN triodes. The first operational amplifier and the second operational amplifier are two operational amplifier units in the same operational amplifier chip.

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