A DCDC power module output overcurrent self-locking isolation protection circuit

Abstract

The present invention discloses an overcurrent self-locking isolation protection circuit for the output of a DCDC power module, which includes a current sampling circuit and a signal amplification circuit, and also includes a signal comparison circuit, an isolation control circuit and a self-locking protection circuit. Among them, the input end of the current sampling circuit is connected to the output end of the DCDC power module, and the current sampling circuit, the signal amplification circuit, the signal comparison circuit, the isolation control circuit and the self-locking protection circuit are connected in sequence. The output end of the self-locking protection circuit is connected to the control pin of the DCDC power module. By connecting the current sampling circuit, the signal amplification circuit, the signal comparison circuit, the isolation control circuit and the self-locking protection circuit in sequence, the present invention can control the control pin of the power module when the output current of the DCDC power module increases, so that the power module shuts off the output. It can protect the power module from damage, and after normal power-on again, the power module can work normally.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly relates to an overcurrent self-locking isolation protection circuit for the output of a DCDC power module. Background Art

[0002] With the continuous development of power electronics technology, the performance requirements of airborne electrical equipment for power modules are getting higher and higher. The power module needs to continuously supply power to the airborne electrical equipment. During the operation of the airborne electrical equipment, the required supply current may suddenly increase. At this time, it may exceed the output current capacity of the power module, resulting in damage to the power module or reduction of the service life of the power module. The existing overcurrent protection circuits cannot simultaneously achieve the functions of isolation control and overcurrent self-locking protection. Summary of the Invention

[0003] The purpose of the present invention is to provide an overcurrent self-locking isolation protection circuit for the output of a DCDC power module to solve the problem that the existing overcurrent protection circuits cannot simultaneously achieve the functions of isolation control and overcurrent self-locking protection.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] An overcurrent self-locking isolation protection circuit for the output of a DCDC power module includes a current sampling circuit and a signal amplification circuit, and further includes a signal comparison circuit, an isolation control circuit and a self-locking protection circuit. Among them, the input end of the current sampling circuit is connected to the output end of the DCDC power module, and the current sampling circuit, the signal amplification circuit, the signal comparison circuit, the isolation control circuit and the self-locking protection circuit are connected in sequence. The output end of the self-locking protection circuit is connected to the control pin of the DCDC power module;

[0006] The current sampling circuit is used for signal acquisition of the output current of the DCDC power module; the signal amplification circuit is used for amplifying the signal obtained by the current sampling circuit; the signal comparison circuit is used for comparing the signal amplified by the signal amplification circuit with a reference signal and sending the signal obtained after comparison to the isolation control circuit; the isolation control circuit is used for generating a control signal according to the signal obtained after comparison sent by the signal comparison circuit and transmitting the control signal to the self-locking protection circuit; the self-locking protection circuit is used for controlling the self-locking protection circuit with the control signal of the isolation control circuit to achieve self-locking when an overcurrent signal comes.

[0007] Further, the current sampling circuit includes a resistor R10, a resistor R11, a voltage stabilizing diode Z1, and a capacitor C3. One end of the resistor R10 is connected to one end of the resistor R11, and the connection point serves as the input end of the current sampling circuit and is connected to the output end of the DCDC power module. The other end of the resistor R10 is commonly connected to one end of the voltage stabilizing diode Z1 and one end of the capacitor C3, and this connection point serves as the input end of the current sampling circuit and is connected to the input end of the signal amplification circuit. The other end of the resistor R11, the other end of the voltage stabilizing diode Z1, and the other end of the capacitor C3 are commonly grounded.

[0008] Further, the signal amplification circuit includes an operational amplifier U3, a resistor R8, and a resistor R9. The 3-pin of the operational amplifier U3 serves as the input end of the signal amplification circuit and is connected to the output end of the current sampling circuit. The 4-pin of the operational amplifier U3 is commonly connected to one end of the resistor R8 and one end of the resistor R9. The 2-pin of the operational amplifier U3 serves as the first output end of the signal amplification circuit and is connected to the first input end of the signal comparison circuit. The other end of the resistor R8 is connected to the 1-pin of the operational amplifier U3, and this connection point serves as the second output end of the signal amplification circuit and is connected to the second input end of the signal comparison circuit. The 5-pin of the operational amplifier U3 is grounded.

[0009] Further, the signal comparison circuit includes a resistor R5, a resistor R6, a resistor R7, a diode D2, and an operational amplifier U2. One end of the resistor R6 is commonly connected to the 2-pin of the operational amplifier U2 and one end of the resistor R5, and this connection point serves as the first input end of the signal comparison circuit and is connected to the first output end of the signal amplification circuit. The other end of the resistor R6 is commonly connected to one end of the resistor R7 and the 4-pin of the operational amplifier U2, and the other end of the resistor R7 is grounded. The 3-pin of the operational amplifier U2 serves as the second input end of the signal comparison circuit and is connected to the second output end of the signal amplification circuit. The 5-pin of the operational amplifier U2 is grounded. The 1-pin of the operational amplifier U2 is commonly connected to one end of the resistor R5 and the anode of the diode D2, and the anode of the diode D2 serves as the output end of the signal comparison circuit and is connected to the input end of the isolation control circuit.

[0010] Further, the isolation control circuit includes a resistor R4 and an optocoupler U1. One end of the resistor R4 serves as the input end of the isolation control circuit and is connected to the output end of the signal comparison circuit. The other end of the resistor R4 is connected to the 1-pin of the optocoupler U1. The 2-pin of the optocoupler U1 is grounded. The 3-pin of the optocoupler U1 is connected to the first input end of the self-locking protection circuit, and the 4-pin of the optocoupler U1 is connected to the second input end of the self-locking protection circuit.

[0011] Further, the self-locking protection circuit includes resistor R1, resistor R2, resistor R3, capacitor C1, capacitor C2, diode D1, triode Q1, and MOS transistor Q2. Among them, the cathode of diode D1 is commonly connected to one end of capacitor C1, one end of resistor R2, the base of triode Q1, and the drain of MOS transistor Q2, and this connection point serves as the first input terminal of the self-locking protection circuit and is connected to the isolation control circuit; the anode of diode D1 serves as the output terminal of the self-locking protection circuit and is connected to the control pin of the DCDC power supply module; the other end of capacitor C1 is commonly connected to one end of resistor R1, the other end of resistor R2, and the emitter of triode Q1; the other end of resistor R1 is connected to the positive input terminal; the collector of triode Q1 is commonly connected to one end of capacitor C2, one end of resistor R3, and the gate of MOS transistor Q2; the other end of capacitor C2 is commonly connected to the other end of resistor R3 and the source of MOS transistor Q2, and this connection point serves as the second input terminal of the self-locking protection circuit and is commonly connected to the ground terminal with the isolation control circuit.

[0012] Compared with the prior art, the technical effects of the present invention are as follows:

[0013] (1) By sequentially connecting the current sampling circuit, signal amplification circuit, signal comparison circuit, isolation control circuit, and self-locking protection circuit, and reasonably setting the parameters of the circuit components, the present invention can control the control pin of the power supply module to turn off the output when the output current of the DC-DC power supply module increases. This can protect the power supply module from damage, and after normal power-on again, the power supply module can work normally.

[0014] (2) The circuit structure of the present invention is easy to implement and has low cost. The over-current point of the module output current can be flexibly and conveniently set according to the sampling circuit, which is applicable to most DC-DC power supply modules. It can effectively prevent the DC-DC power conversion module from being damaged or unable to work normally when the output current increases, improving the safety and reliability of the power supply module. It is an over-current self-locking isolation protection circuit with excellent performance, simplicity, and practicality.

[0015] (3) Each circuit of the present invention is composed of discrete components, and the over-current point can be set according to needs, which is flexible, convenient to use, and has low cost. Description of the Drawings

[0016] Figure 1 It is a structural block diagram of the over-current self-locking isolation protection circuit for the DCDC power supply module output of the present invention.

[0017] Figure 2 It is the circuit schematic diagram of the embodiment of the present invention. Detailed Embodiment

[0018] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0019] As Figure 1 shown, the over-current self-locking isolation protection circuit for the output of the DCDC power module provided by the present invention includes a current sampling circuit 1, a signal amplification circuit 2, a signal comparison circuit 3, an isolation control circuit 4, and a self-locking protection circuit 5. Among them, the input end of the current sampling circuit 1 is connected to the output end of the DCDC power module. The current sampling circuit 1, the signal amplification circuit 2, the signal comparison circuit 3, the isolation control circuit 4, and the self-locking protection circuit 5 are connected in sequence. The output end of the self-locking protection circuit 5 is connected to the control pin of the DCDC power module.

[0020] In the above technical solution, the current sampling circuit 1 is used to collect the signal of the output current of the DCDC power module; the signal amplification circuit 2 is used to amplify the signal obtained by the current sampling circuit 1; the signal comparison circuit 3 is used to compare the signal amplified by the signal amplification circuit 2 with the reference signal, and send the signal obtained after the comparison to the isolation control circuit 4; the isolation control circuit 4 is used to generate a control signal according to the signal obtained after the comparison sent by the signal comparison circuit 3, and transmit the control signal to the self-locking protection circuit 5; the self-locking protection circuit 5 is used to control the self-locking protection circuit 5 with the control signal of the isolation control circuit 4 to achieve self-locking when the over-current signal comes.

[0021] Embodiment 1:

[0022] This embodiment is a preferred embodiment of the present invention. Please refer to Figure 2 , in the over-current self-locking isolation protection circuit for the output of the DCDC power module given in this embodiment, the circuits are set as follows:

[0023] The current sampling circuit 1 includes a resistor R10, a resistor R11, a voltage regulator diode Z1, and a capacitor C3. Among them, one end of the resistor R10 is connected to one end of the resistor R11, and this connection point serves as the input end of the current sampling circuit 1 and is connected to the output end of the DCDC power module (terminal A, current signal); the other end of the resistor R10 is commonly connected to one end of the voltage regulator diode Z1 and one end of the capacitor C3, and this connection point serves as the input end of the current sampling circuit 1 and is connected to the input end of the signal amplification circuit 2; the other end of the resistor R11, the other end of the voltage regulator diode Z1, and the other end of the capacitor C3 are commonly grounded.

[0024] The signal amplification circuit 2 includes an operational amplifier U3, a resistor R8, and a resistor R9. Among them, the 3rd pin of the operational amplifier U3 serves as the input terminal of the signal amplification circuit 2 and is connected to the output terminal of the current sampling circuit 1; the 4th pin of the operational amplifier U3 is commonly connected to one end of the resistor R8 and one end of the resistor R9; the 2nd pin of the operational amplifier U3 serves as the first output terminal VCC of the signal amplification circuit 2 and is connected to the first input terminal of the signal comparison circuit 3; the other end of the resistor R8 is connected to the 1st pin of the operational amplifier U3, and this connection point serves as the second output terminal of the signal amplification circuit 2 and is connected to the second input terminal of the signal comparison circuit 3; the 5th pin of the operational amplifier U3 is grounded.

[0025] The signal comparison circuit 3 includes a resistor R5, a resistor R6, a resistor R7, a diode D2, and an operational amplifier U2. Among them, one end of the resistor R6 is commonly connected to the 2nd pin of the operational amplifier U2 and one end of the resistor R5, and this connection point serves as the first input terminal of the signal comparison circuit 3 and is connected to the first output terminal VCC of the signal amplification circuit 2; the other end of the resistor R6 is commonly connected to one end of the resistor R7 and the 4th pin of the operational amplifier U2, and the other end of the resistor R7 is grounded; the 3rd pin of the operational amplifier U2 serves as the second input terminal of the signal comparison circuit 3 and is connected to the second output terminal of the signal amplification circuit 2; the 5th pin of the operational amplifier U2 is grounded; the 1st pin of the operational amplifier U2 is commonly connected to one end of the resistor R5 and the anode of the diode D2, and the anode of the diode D2 serves as the output terminal of the signal comparison circuit 3 and is connected to the input terminal of the isolation control circuit 4.

[0026] The isolation control circuit 4 includes a resistor R4 and an optocoupler U1. Among them, one end of the resistor R4 serves as the input terminal of the isolation control circuit 4 and is connected to the output terminal of the signal comparison circuit 3; the other end of the resistor R4 is connected to the 1st pin of the optocoupler U1; the 2nd pin of the optocoupler U1 is grounded; the 3rd pin of the optocoupler U1 is connected to the first input terminal of the self-locking protection circuit 5, and the 4th pin of the optocoupler U1 is connected to the second input terminal of the self-locking protection circuit 5.

[0027] The self-locking protection circuit 5 includes a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, a diode D1, a triode Q1, and a MOS transistor Q2. Among them, the cathode of the diode D1 is commonly connected to one end of the capacitor C1, one end of the resistor R2, the base of the triode Q1, and the drain of the MOS transistor Q2, and this connection point serves as the first input terminal of the self-locking protection circuit 5 and is connected to the isolation control circuit 4; the anode of the diode D1 serves as the output terminal of the self-locking protection circuit 5 and is connected to the control pin EN of the DCDC power supply module; the other end of the capacitor C1 is commonly connected to one end of the resistor R1, the other end of the resistor R2, and the emitter of the triode Q1; the other end of the resistor R1 is connected to the positive power supply terminal VIN+ of the circuit of the present invention; the collector of the triode Q1 is commonly connected to one end of the capacitor C2, one end of the resistor R3, and the gate of the MOS transistor Q2; the other end of the capacitor C2 is commonly connected to the other end of the resistor R3 and the source of the MOS transistor Q2, and this connection point serves as the second input terminal of the self-locking protection circuit 5 and is commonly connected to the ground terminal VIN- of the isolation control circuit 4.

[0028] To clearly understand the structural composition and overall operation mode of the present invention, the detailed working process of the present invention is described as follows:

[0029] The current signal A is connected to the current sampling circuit 1 composed of the resistor R10, the resistor R11, the voltage regulator Z1 and the capacitor C3. The sampled signal is given to the signal amplifying circuit 2. The signal amplifying circuit 2 is used to amplify the obtained signal in a certain proportion and compare the amplified signal with the reference signal of the signal comparison circuit 3. When the amplified signal value is higher than the reference signal, the signal comparison circuit 3 outputs a high-level voltage, and the high-level voltage is transmitted to the isolation control circuit 4. The resistor R4 in the isolation control circuit 4 limits the current and then gives it to the optocoupler U1. The light-emitting diode inside the optocoupler U1 works to turn on the triode inside the optocoupler U1, thereby realizing the isolation control in the output overcurrent isolation self-locking protection circuit of the present invention. The isolation control circuit 4 transmits the control signal to the self-locking protection circuit 5. The diode D1 in the self-locking protection circuit 5 connects the power supply The control terminal EN of the module is pulled down to a low level, the DCDC power module is turned off at this time, the base of the transistor Q1 in the self-locking protection circuit 5 is also at a low level, the transistor Q1 works in the on state, the positive power supply terminal VIN+ passes through the transistor Q1 to the gate of the MOS tube Q2, at this time the gate of the MOS tube Q2 is at a high level, the MOS tube Q2 works in the on state, and the control terminal EN of the DCDC power module connected to the diode D1 is also pulled down to a low level, and the base of the transistor Q1 is also pulled down to a low level, if the overcurrent signal A is cancelled at this time, since there is always a voltage at the positive power supply terminal VIN+, the transistor Q1 and the MOS tube Q2 will always be in the on state, the EN terminal of the DCDC power module connected to the diode D1 is also always at a low level, and the DCDC power module is in the off state. Only after the positive power supply terminal VIN+ is turned off and then powered on again, the self-locking protection circuit 5 will be released from the working state, thereby realizing the self-locking protection function in the output overcurrent isolation self-locking protection circuit of the present invention.

[0030] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be thought of by any technician familiar with the field within the technical scope disclosed by the present invention without creative work should be covered within the protection scope of the present invention.

Claims

1. A DCDC power module output overcurrent self-locking isolation protection circuit, comprising a current sampling circuit (1) and a signal amplification circuit (2), characterized in that: It also includes a signal comparison circuit (3), an isolation control circuit (4) and a self-locking protection circuit (5), wherein the input end of the current sampling circuit (1) is connected to the output end of the DCDC power module, the current sampling circuit (1), the signal amplification circuit (2), the signal comparison circuit (3), the isolation control circuit (4) and the self-locking protection circuit (5) are connected in sequence, and the output end of the self-locking protection circuit (5) is connected to the control pin of the DCDC power module; The current sampling circuit (1) is used to collect the signal of the output current of the DCDC power module; the signal amplification circuit (2) is used to amplify the signal obtained by the current sampling circuit (1); the signal comparison circuit (3) is used to compare the signal amplified by the signal amplification circuit (2) with a reference signal, and transmit the signal obtained after the comparison to the isolation control circuit (4); the isolation control circuit (4) is used to generate a control signal according to the signal obtained after the comparison sent by the signal comparison circuit (3), and transmit the control signal to the self-locking protection circuit (5); the self-locking protection circuit (5) is used to realize self-locking when receiving an overcurrent signal; The isolation control circuit (4) comprises a resistor R4 and an optical coupler U1, wherein one end of the resistor R4 is connected to the output end of the signal comparison circuit (3) as the input end of the isolation control circuit (4); the other end of the resistor R4 is connected to pin 1 of the optical coupler U1; pin 2 of the optical coupler U1 is grounded; pin 3 of the optical coupler U1 is connected to the first input end of the self-locking protection circuit (5), and pin 4 of the optical coupler U1 is connected to the second input end of the self-locking protection circuit (5); The self-locking protection circuit (5) comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, a diode D1, a transistor Q1 and a MOS transistor Q2, wherein the cathode of the diode D1 is commonly connected to one end of the capacitor C1, one end of the resistor R2, the base of the transistor Q1 and the drain of the MOS transistor Q2, and the connection point is connected to the isolation control circuit (4) as the second input end of the self-locking protection circuit (5); the anode of the diode D1 is connected to the DCDC circuit as the output end of the self-locking protection circuit (5). The control pin of the source module is connected; the other end of the capacitor C1 is connected to one end of the resistor R1, the other end of the resistor R2, and the emitter of the transistor Q1; the other end of the resistor R1 is connected to the input positive terminal; the collector of the transistor Q1 is connected to one end of the capacitor C2, one end of the resistor R3, and the gate of the MOS transistor Q2; the other end of the capacitor C2 is connected to the other end of the resistor R3 and the source of the MOS transistor Q2, and the connection point is connected to the ground terminal together with the isolation control circuit (4) as the first input terminal of the self-locking protection circuit (5).

2. The DCDC power module output overcurrent self-locking isolation protection circuit according to claim 1, characterized in that: The current sampling circuit (1) comprises a resistor R10, a resistor R11, a voltage regulator Z1 and a capacitor C3, wherein one end of the resistor R10 is connected to one end of the resistor R11, and the connection point is connected to the output end of the DCDC power module as the input end of the current sampling circuit (1); the other end of the resistor R10 is commonly connected to one end of the voltage regulator Z1 and one end of the capacitor C3, and the connection point is connected to the input end of the signal amplification circuit (2) as the output end of the current sampling circuit (1); the other end of the resistor R11, the other end of the voltage regulator Z1 and the other end of the capacitor C3 are commonly grounded.

3. The DCDC power module output overcurrent self-locking isolation protection circuit according to claim 2, characterized in that: The signal amplification circuit (2) comprises an operational amplifier U3, a resistor R8 and a resistor R9, wherein the pin 3 of the operational amplifier U3 is connected to the output end of the current sampling circuit (1) as the input end of the signal amplification circuit (2); the pin 4 of the operational amplifier U3 is connected to one end of the resistor R8 and one end of the resistor R9; the pin 2 of the operational amplifier U3 is connected to the first input end of the signal comparison circuit (3); the other end of the resistor R8 is connected to the pin 1 of the operational amplifier U3, and the connection point is connected to the second input end of the signal comparison circuit (3) as the output end of the signal amplification circuit (2); and the pin 5 of the operational amplifier U3 is grounded.

4. The DCDC power module output overcurrent self-locking isolation protection circuit according to claim 3, characterized in that: The signal comparison circuit (3) comprises a resistor R5, a resistor R6, a resistor R7, a diode D2 and an operational amplifier U2, wherein one end of the resistor R6 is connected to pin 2 of the operational amplifier U2 and one end of the resistor R5, and the connection point is connected to the signal amplification circuit (2) as a first input end of the signal comparison circuit (3); the other end of the resistor R6 is connected to one end of the resistor R7 and pin 4 of the operational amplifier U2, and the other end of the resistor R7 is grounded; pin 3 of the operational amplifier U2 is connected to the output end of the signal amplification circuit (2) as a second input end of the signal comparison circuit (3); pin 5 of the operational amplifier U2 is grounded; pin 1 of the operational amplifier U2 is connected to the other end of the resistor R5 and the anode of the diode D2, and the anode of the diode D2 is connected to the input end of the isolation control circuit (4) as the output end of the signal comparison circuit (3).

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