Output isolation MOS tube anti-backflow control circuit

Abstract

The invention discloses an output isolation MOS tube anti-backflow control circuit, and belongs to the technical field of secondary power supplies of spacecrafts. The circuit comprises a power control power supply U1, resistors R1 to R3, diodes D1 to D2, triodes Q1 to Q2, a capacitor C0 and an MOS tube M1, the MOS tube M1 is cut off by sampling voltages at two ends of the MOS tube M1 when the voltage of a source S of the MOS tube is lower than the voltage of a drain D, so that the secondary power supply output without faults is prevented from being reversely injected into the faulted secondary power supply, and the normal work of the output voltage after the secondary power supplies are connected in parallel is protected.

Description

Technical Field

[0001] The invention relates to an output isolation MOS tube backflow prevention control circuit, belonging to the technical field of spacecraft secondary power supplies. Background Art

[0002] Spacecraft secondary power supplies are crucial devices that provide various power supplies for individual electronic components. Due to the high reliability requirements of aerospace, secondary power supply outputs often utilize a primary / backup redundant design. Therefore, isolation between the primary and backup secondary power supply outputs is required. When the secondary power supply output current is low, diode isolation can be used. While this isolation method is simple and reliable, it generates significant heat dissipation, making it unsuitable for high-current isolation circuits. Due to the low on-resistance of power MOSFETs, they are often used for output isolation in situations with high output currents to reduce heat dissipation and improve conversion efficiency. Furthermore, as spacecraft platform and payload capabilities continue to increase, power demands are also rising. Secondary power supplies often utilize multiple units connected in parallel to meet these high-power output requirements. Therefore, when the output current is high, MOSFETs are used as isolation transistors for the parallel outputs to reduce heat dissipation.

[0003] When using MOS transistors as output isolation transistors, if an output short circuit occurs in a secondary power supply, the isolation MOS transistor of the faulty secondary power supply cannot be turned off in time, causing the output voltage of the parallel-connected module to flow back to the faulty module, causing the output bus power supply to lose power, affecting the normal operation of the subsequent electronic equipment. In serious cases, it can cause the spacecraft to fail to perform its mission.

[0004] After searching relevant domestic and foreign literature, no output isolation and anti-backflow control circuit related to the present invention was found. Summary of the Invention

[0005] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and propose an output isolation MOS tube backflow prevention control circuit for preventing backflow caused by secondary power failure and protecting connected load devices.

[0006] The technical solution of the present invention is:

[0007] An output isolation MOS tube anti-backflow control circuit includes a control power supply U1, resistors R1-R3, diodes D1-D2, transistors Q1-Q2, capacitor C0, and MOS tube M1;

[0008] The positive electrode of the control power supply U1 is connected to the resistor R1 and the resistor R2 respectively; the other end of the resistor R1 is connected to the collector of the transistor Q1, the capacitor C0, the resistor R3, and the gate of the MOS transistor M1 respectively; the other end of the resistor R2 is connected to the collector and base of the transistor Q2 and the base of the transistor Q1 respectively;

[0009] The emitter of transistor Q1 is connected to the anode of diode D1;

[0010] The emitter of transistor Q2 is connected to the anode of diode D2;

[0011] The negative electrode of the control power supply U1, the other end of the resistor R3, the cathode of the diode D1, the source gate of the MOS tube M1, and the other end of the capacitor C0 are all connected to the output positive line of the secondary power supply;

[0012] The drain of the MOS tube M1 is connected to the cathode of the diode D2 and serves as the output end of the output isolation MOS tube anti-backflow control circuit to be connected to the load.

[0013] Furthermore, the resistor R1, the resistor R2, the transistor Q1, the transistor Q2, the diode D1 and the diode D2 form a current mirror circuit to sample the voltage between the source and the drain of the isolation MOS transistor M1.

[0014] Furthermore, the resistor R1, the resistor R3 and the output filter capacitor of the secondary power supply form a driving circuit of the MOS transistor M1.

[0015] Furthermore, the gate driving voltage of the MOS transistor M1 is greater than 7V.

[0016] Furthermore, the control power supply U1 provides power for the anti-backflow control circuit, and the power supply voltage range is between 10V and 15V.

[0017] Furthermore, transistors Q1 and Q2 are selected to have the same temperature characteristics.

[0018] Furthermore, the diode D1 and the diode D2 are selected to have the same temperature characteristics.

[0019] Furthermore, the specifications of the resistors R1 and R2 are consistent, and the recommended resistance range is 2kΩ to 5.1kΩ; the resistance of the resistor R3 is more than 5 times the resistance of the resistor R1, and the recommended resistance range is 10kΩ to 50kΩ.

[0020] Furthermore, if there are multiple secondary power supplies connected in parallel to supply power to the load, an output isolation MOS tube backflow prevention control circuit is first connected to the output end of each secondary power supply before supplying power to the load.

[0021] The advantages of the present invention compared with the prior art are:

[0022] (1) In the present invention, the output isolation MOS tube backflow prevention control circuit samples the voltage across the isolation MOS tube M1, with high sampling accuracy and fast response speed. When protection occurs, the output voltage Uo drops by more than 5% of the rated output. In the prior art, when a fault mode occurs, the output voltage drops to zero.

[0023] (2) The present invention uses common passive devices such as MOS tubes, diodes, transistors, capacitors, resistors, etc. as the components of the circuit, which is simple, small in size, and has low circuit implementation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0025] Figure 1 This is a structural diagram of an output isolation MOS tube backflow prevention control circuit according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the application of an output isolation MOS tube backflow prevention control circuit after multiple secondary power supply output ports are connected in parallel in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0028] The present invention proposes an output isolation MOS tube anti-backflow control circuit, such as Figure 1 As shown, it includes a control power supply U1, resistors R1~R3, diodes D1~D2, transistors Q1~Q2, capacitor C0, and MOS tube M1.

[0029] The control power supply U1 supplies power to the output isolation MOS tube anti-backflow control circuit. The positive electrode is connected to resistors R1 and R2, and the negative electrode is connected to the output positive line of the secondary power supply. At the same time, it is connected to one end of resistor R3, the cathode of diode D1, the source gate of MOS tube M1, and one end of capacitor C0; the other end of resistor R1 is connected to the collector of transistor Q1, the other end of capacitor C0, the other end of resistor R3, and the gate of MOS tube M1; the other end of resistor R2 is connected to the collector and base of transistor Q2, and the base of transistor Q1; the emitter of transistor Q1 is connected to the anode of diode D1; the emitter of transistor Q2 is connected to the anode of diode D2; the drain of MOS tube M1 is connected to the cathode of diode D2 and the output load R L Capacitor C1 is the output filter capacitor of the secondary power supply, and resistor RL is the output load of the secondary power supply.

[0030] The supply voltage range of the control power supply U1 is between 10V and 15V.

[0031] Resistors R1 and R2, transistors Q1 and Q2, diodes D1 and D2 form a current mirror circuit to sample the voltage between the source and drain of isolation MOS transistor M1. Transistors Q1 and Q2, and diodes D1 and D2 must have consistent temperature characteristics; paired transistors are recommended.

[0032] Resistors R1, R3, and C1 form the drive circuit for the isolated MOS transistor. During design, it is necessary to ensure that the gate drive voltage of the isolated MOS transistor is greater than 7V.

[0033] Figure 2 This is an application circuit for an output isolation backflow prevention control circuit. N secondary power supplies are connected in parallel through the output isolation backflow prevention control circuit. The output isolation backflow prevention control circuit collects the voltage between the source and drain of the output isolation MOS transistor. During normal operation, the source S voltage of the isolation MOS transistor M1 is higher than the drain D voltage, the isolation MOS transistor M1 conducts, and each secondary power supply outputs normally. If one or more secondary power supplies experience an output short circuit fault, the source S voltage of the isolation MOS transistor is lower than the drain D voltage, and the isolation MOS transistor M1 is turned off. This prevents the output of the intact secondary power supply from backflowing into the faulty secondary power supply, thereby protecting the normal operation of the output voltage Uo of the N secondary power supplies connected in parallel.

[0034] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. An output isolation MOS tube anti-backflow control circuit, characterized in that: Including control power supply U1, resistors R1~R3, diodes D1~D2, transistors Q1~Q2, capacitor C0, MOS tube M1; The positive electrode of the control power supply U1 is connected to the resistor R1 and the resistor R2 respectively; the other end of the resistor R1 is connected to the collector of the transistor Q1, the capacitor C0, the resistor R3, and the gate of the MOS transistor M1 respectively; the other end of the resistor R2 is connected to the collector and base of the transistor Q2 and the base of the transistor Q1 respectively; The emitter of transistor Q1 is connected to the anode of diode D1; The emitter of transistor Q2 is connected to the anode of diode D2; The negative electrode of the control power supply U1, the other end of the resistor R3, the cathode of the diode D1, the source gate of the MOS tube M1, and the other end of the capacitor C0 are all connected to the output positive line of the secondary power supply; The drain of the MOS tube M1 is connected to the cathode of the diode D2 and serves as the output end of the output isolation MOS tube anti-backflow control circuit to be connected to the load.

2. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: Resistor R1, resistor R2, transistor Q1, transistor Q2, diode D1 and diode D2 form a current mirror circuit to sample the voltage between the source and drain of the isolation MOS transistor M1.

3. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: The resistor R1, the resistor R3 and the output filter capacitor of the secondary power supply form a driving circuit of the MOS tube M1.

4. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: The gate drive voltage of the MOS tube M1 is greater than 7V.

5. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: The control power supply U1 provides power for the anti-backflow control circuit, and the power supply voltage range is between 10V and 15V.

6. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: Transistor Q1 and transistor Q2 are selected to have the same temperature characteristics.

7. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: The diodes D1 and D2 are selected to have the same temperature characteristics.

8. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: The resistors R1 and R2 have the same specifications, and the resistance of the resistor R3 is more than 5 times the resistance of the resistor R1.

9. The output isolation MOS tube anti-backflow control circuit according to claim 1, characterized in that: If there are multiple secondary power supplies connected in parallel to supply power to the load, then the output end of each secondary power supply is first connected to an output isolation MOS tube anti-backflow control circuit before supplying power to the load.

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