28V output anti-delay protection circuit

Abstract

The invention discloses a 28V output anti-delay protection circuit, which comprises a 28V input source, a first reference comparison circuit, a second reference comparison circuit, a quick discharge circuit and an anti-delay reference change circuit, the first reference comparison circuit is composed of a first voltage division circuit, a comparator U2A, a first charging capacitor, a comparator U2B, an overvoltage signal overturning circuit and an overvoltage protection signal locking circuit, and the second reference comparison circuit is provided with a second voltage division circuit, a comparator U28A, a resistor R453, a diode D38 and a second charging capacitor. The rapid discharging circuit is used for rapidly discharging the second charging capacitor; the reference chip, the operational amplifier comparison circuit and the RC delay circuit are adopted to form an anti-delay protection circuit, the larger the output voltage is, the shorter the response time of the protection circuit is, the shorter the time of the enabling signal of the power module controlled by the finally output signal and the action time of the protection circuit is, and therefore the situation that on-board 28V electric equipment is damaged due to the too high input voltage is avoided.

Description

Technical Field

[0001] This invention relates to the field of protection circuits for aviation secondary power converters, specifically a 28V output inverse delay protection circuit. Background Technology

[0002] In the secondary power supply subsystem of the aircraft power supply subsystem, overvoltage faults in the output of the 270V (540V) / 28V power converter pose a significant threat to downstream electrical loads and the secondary power supply subsystem itself. Given that the output of the 270V (540V) / 28V power converter is a low voltage of 28VDC, existing output protection circuits for the 28V power converter suffer from problems such as power circuit faults or loop control faults leading to excessively high output voltages that damage downstream electrical equipment and exacerbate aircraft malfunctions. Therefore, a 28V output inverse delay protection circuit is proposed. Summary of the Invention

[0003] The purpose of this invention is to provide a 28V output inverse delay protection circuit to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a 28V output inverse delay protection circuit, comprising... 28V input source The first reference comparator circuit consists of a voltage divider circuit, comparator U2A, a charging capacitor, comparator U2B, an overvoltage signal flipping circuit, and an overvoltage protection signal lockout circuit. The voltage divider circuit divides the 28V input source and compares it with the reference voltage VREF3 of comparator U2A. When the non-inverting input of comparator U2A is higher than the reference voltage VREF3, the output of comparator U2A outputs a high level VDD and charges the charging capacitor through resistor R246. One end of the charging capacitor is connected to the non-inverting input of comparator U2B. When the voltage of the charging capacitor exceeds the reference voltage of comparator U2B, the overvoltage protection signal lockout circuit is activated. The second reference comparator circuit has a second voltage divider circuit, a comparator U28A, a resistor R453, a diode D38, and a second charging capacitor. The second voltage divider circuit is used to divide the 28V input source and compare it with the reference voltage VREF3 of the comparator U28A. A fast discharge circuit is used to quickly discharge the second charging capacitor. The fast discharge circuit consists of Zener diode Z1, Zener diode Z6, resistor R468, resistor R467, resistor R466 and transistor Q51. Zener diode Z6 is connected in series with Zener diode Z1 and the reverse terminal of Zener diode Z6 is connected to a 28V input source. The inverse delay reference change circuit has a third operational amplifier and a third comparator. The third operational amplifier is used to amplify the 28V input source. The output voltage of the third operational amplifier enters the non-inverting input of the third comparator through resistor R454 to serve as the reference voltage of the third comparator. The inverting input of the third comparator is connected to the second charging capacitor.

[0005] Furthermore, the overvoltage signal flipping circuit includes a comparator U29B, and the overvoltage protection signal locking circuit consists of resistors R455, R461, R321, capacitor C312, resistor R460, and transistor Q50. The output terminal of comparator U29B is connected to resistors R461 and R321. The non-inverting input terminal of comparator U29B is connected to the output terminal of the third comparator through resistor R456 and diode D39. The base of transistor Q50 is connected between resistors R461 and R321, and the collector of transistor Q50 is connected to the inverting input terminal of comparator U29B through resistor R462.

[0006] Furthermore, the base of transistor Q51 is connected to a charging capacitor C316, resistor R468, and resistor R467. When the output voltage of the second charging capacitor is lower than 34V, transistor Q51 cannot conduct. When the output voltage of the second charging capacitor exceeds 34V, as the output voltage increases, it breaks down Zener diodes Z6 and Z1, and then conducts through the voltage divider between resistors R468 and R467, causing transistor Q51 to conduct. The faster the charging speed of the charging capacitor C316, the faster the transistor Q51 conducts.

[0007] The beneficial effects of this invention are as follows: This invention uses a reference chip + operational amplifier comparator circuit + RC delay circuit to form an anti-delay protection circuit. As the output voltage increases, the response time of the protection circuit is faster. The final output signal controls the enable signal of the power module, and the protection circuit operates faster, thereby avoiding damage to the 28V electrical equipment on the machine due to excessive input voltage. It can adapt to abnormal loop and power circuit conditions and can be used at the output of various 28V low-voltage DC electronic equipment. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the 28V output anti-delay protection circuit of the present invention; Figure 2 This is a schematic diagram of the 28V output anti-delay protection circuit architecture of the present invention.

[0009] In the diagram: 1. First reference comparator circuit; 11. Voltage divider circuit 1; 12. Charging capacitor 1; 13. Fixed delay circuit; 14. Overvoltage signal flip circuit; 15. Overvoltage protection signal lockout circuit; 2. Second reference comparator circuit; 21. Voltage divider circuit 2; 3. 28V input source; 4. Charging capacitor 2; 5. Fast discharge circuit; 6. Third operational amplifier; 7. Third comparator. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] Please see Figure 1-2 This invention provides a technical solution: a 28V output anti-delay protection circuit, comprising a 28V input source 3, a first reference comparator circuit 1, a second reference comparator circuit 2, a fast discharge circuit 5, and an anti-delay reference change circuit. The first reference comparator circuit 1 consists of a voltage divider circuit 11, a comparator U2A, a charging capacitor 12, a comparator U2B, an overvoltage signal flipping circuit 14, and an overvoltage protection signal locking circuit 15. The voltage divider circuit 11 is used to divide the 28V input source 3 and compare it with the reference voltage VREF3 of the comparator U2A. When the non-inverting input of comparator U2A is higher than the reference voltage VREF3, the output of comparator U2A outputs a high level VDD and charges the first charging capacitor 12 through resistor R246. One end of the first charging capacitor 12 is connected to the non-inverting input of comparator U2B. When the voltage of the first charging capacitor 12 exceeds the reference voltage of comparator U2B, the overvoltage protection signal lockout circuit 15 is entered. Among them, comparator U2A, the first charging capacitor 12, and comparator U2B constitute a fixed delay circuit 13. The first charging capacitor 12 can be marked as capacitor C130.

[0012] The second reference comparison circuit 2 includes a second voltage divider circuit 21, a comparator U28A, a resistor R453, a diode D38, and a second charging capacitor 4. The second voltage divider circuit 21 is used to divide the 28V input source 3 and compare it with the reference voltage VREF3 of the comparator U28A. The fast discharge circuit 5 is used to quickly discharge the second charging capacitor 4. The fast discharge circuit 5 consists of Zener diodes Z1 and Z6, resistors R468, R467, and R466, and transistor Q51. Zener diodes Z6 and Z1 are connected in series, and the inverting terminal of Zener diode Z6 is connected to the 28V input source 3. The base of transistor Q51 is connected to charging capacitor C316, resistors R468 and R467. When the output voltage of the second charging capacitor is lower than 34V, transistor Q51 cannot conduct. When the output voltage of the second charging capacitor exceeds 34V, as the output voltage increases, Zener diodes Z6 and Z1 break down and conduct. Then, the voltage is divided by resistors R468 and R467 to make transistor Q51 conduct. The faster the charging speed of charging capacitor C316, the faster transistor Q51 conducts. The inverse delay reference change circuit includes a third operational amplifier 6 and a third comparator 7. The third operational amplifier 6 is used to amplify the 28V input source 3. The output voltage of the third operational amplifier 6 enters the non-inverting input of the third comparator 7 through resistor R454 to serve as the reference voltage of the third comparator 7. The inverting input of the third comparator 7 is connected to the second charging capacitor 4.

[0013] In this embodiment, the overvoltage signal switching circuit 14 has a comparator U29B, and the overvoltage protection signal locking circuit 15 consists of resistors R455, R461, R321, capacitor C312, resistor R460, and transistor Q50. The output terminal of the comparator U29B is connected to resistors R461 and R321. The non-inverting input terminal of the comparator U29B is connected to the output terminal of the third comparator 7 through resistor R456 and diode D39. The base of the transistor Q50 is connected between resistors R461 and R321, and the collector of the transistor Q50 is connected to the inverting input terminal of the comparator U29B through resistor R462. The third operational amplifier 6 can be labeled as operational amplifier U28B, and the third comparator 7 can be labeled as comparator U29A.

[0014] The 28V output inverse delay protection circuit consists of a voltage divider circuit 11 composed of parallel resistors R243, R244, and R23. The first reference comparator circuit 1 divides the 28V input source 3 through the voltage divider circuit 11 and compares it with the reference voltage VREF3. When the voltage at pin 3 of comparator U2A is higher than the voltage at pin 2, it enters the fixed delay circuit 13. The high level output VDD from pin 1 of comparator U2A charges the charging capacitor C130 through resistor R246. When the charging voltage is higher than the voltage at pin 6 of comparator U2B, the high level output from pin 7 of comparator U2B is entered. Then, it enters the overvoltage signal flipping circuit 14, which makes the voltage at pin 5 of comparator U29B higher than the voltage at pin 6. The high level output from pin 7 of comparator U29B is entered. Finally, it enters the overvoltage protection signal locking circuit 15, which divides the voltage through resistors R461 and R321 to turn on transistor Q50, pulling the sixth pin of comparator U29B low to achieve overvoltage protection signal locking. The second reference comparator circuit 2's second voltage divider circuit 21 consists of parallel resistors R448, R398, and R465. The second voltage divider circuit 21 divides the 28V input source 3 and compares it with the reference voltage VREF3. When the voltage at pin 3 of comparator U28A is higher than the voltage at pin 2, pin 1 of comparator U28A outputs a high level. Diode D38 and resistor R453 quickly charge capacitor C311, causing the voltage at pin 2 of comparator U28A to approximately reach the AVCCS voltage value. When the overvoltage protection circuit is triggered, the voltage at pin 3 of comparator U28A falls below the voltage at pin 2, and pin 1 of comparator U28A outputs a low level. Capacitor C311 discharges through resistors R452 and R457, and simultaneously discharges through the fast discharge circuit 5. When the output voltage is below 34V, transistor Q51 cannot conduct, and the discharge circuit is ineffective. When the output voltage exceeds 34V, as the voltage increases, Zener diodes Z6 and Z1 break down and conduct. Through resistors R468 and R467, a voltage divider is formed, causing transistor Q51 to conduct. When transistor Q51 is in the amplification region, the higher the voltage, the greater the current in transistor Ib and Ic, resulting in a faster discharge speed, until transistor Q51 enters the saturation region. Although this no longer affects the discharge circuit speed, the higher the output voltage, the more the charging capacitor C31... The faster the charging speed of 6, the faster the transistor Q51 turns on, and the faster the newly added discharge circuit is connected to discharge. Among them, the inverse delay reference change circuit amplifies the output voltage through operational amplifier U28B. As the output voltage increases, the voltage at pin 5 of operational amplifier U28B increases synchronously, and the voltage at pin 7 of operational amplifier U28B increases synchronously. Pin 7 of operational amplifier U28B is connected to pin 3 of comparator U29A through resistor R454, serving as the reference voltage for comparator U29A. The higher the output voltage, the higher the reference voltage.

[0015] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0016] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be understood that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. In the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can refer to a mechanical connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. Among these, there are various ways of detachable installation, such as by using a combination of plug-in and snap-fit, or by using bolt connections, etc.

[0017] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A 28V output inverse delay protection circuit, characterized in that, Including a 28V input source, The first reference comparator circuit consists of a voltage divider circuit, comparator U2A, a charging capacitor, comparator U2B, an overvoltage signal flipping circuit, and an overvoltage protection signal lockout circuit. The voltage divider circuit divides the 28V input source and compares it with the reference voltage VREF3 of comparator U2A. When the non-inverting input of comparator U2A is higher than the reference voltage VREF3, the output of comparator U2A outputs a high level VDD and charges the charging capacitor through resistor R246. One end of the charging capacitor is connected to the non-inverting input of comparator U2B. When the voltage of the charging capacitor exceeds the reference voltage of comparator U2B, the overvoltage protection signal lockout circuit is activated. The second reference comparator circuit has a second voltage divider circuit, a comparator U28A, a resistor R453, a diode D38, and a second charging capacitor. The second voltage divider circuit is used to divide the 28V input source and compare it with the reference voltage VREF3 of the comparator U28A. A fast discharge circuit is used to quickly discharge the second charging capacitor. The fast discharge circuit consists of Zener diode Z1, Zener diode Z6, resistor R468, resistor R467, resistor R466 and transistor Q51. Zener diode Z6 is connected in series with Zener diode Z1 and the reverse terminal of Zener diode Z6 is connected to a 28V input source. The inverse delay reference change circuit has a third operational amplifier and a third comparator. The third operational amplifier is used to amplify the 28V input source. The output voltage of the third operational amplifier enters the non-inverting input of the third comparator through resistor R454 to serve as the reference voltage of the third comparator. The inverting input of the third comparator is connected to the second charging capacitor.

2. The 28V output inverse delay protection circuit according to claim 1, characterized in that: The overvoltage protection signal lockout circuit consists of comparator U29B, resistors R455, R461, R321, capacitor C312, resistor R460, and transistor Q50. The output terminal of comparator U29B is connected to resistors R461 and R321. The non-inverting input terminal of comparator U29B is connected to the output terminal of a third comparator through resistor R456 and diode D39. The base of transistor Q50 is connected between resistors R461 and R321, and the collector of transistor Q50 is connected to the inverting input terminal of comparator U29B through resistor R462.

3. The 28V output inverse delay protection circuit according to claim 1, characterized in that: The base of transistor Q51 is connected to a charging capacitor C316, resistors R468 and R467. When the output voltage of the second charging capacitor is below 34V, transistor Q51 cannot conduct. When the output voltage of the second charging capacitor exceeds 34V, as the output voltage increases, it breaks down Zener diodes Z6 and Z1, and then conducts through the voltage divider between resistors R468 and R467, turning on transistor Q51. The faster the charging capacitor C316 charges, the faster transistor Q51 turns on.

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