A rapid detection circuit for airborne AC power failure

Abstract

This utility model discloses an airborne AC power supply failure rapid detection circuit, including a transformer circuit, an operational amplifier, a voltage comparator, and a linear regulator. The transformer circuit is connected to the operational amplifier, and the voltage comparator is connected to both the linear regulator and the operational amplifier. The transformer circuit rectifies the high-voltage AC power into low-voltage DC power and obtains an electrical signal. The operational amplifier amplifies the electrical signal and compares it with a reference voltage generated by the linear regulator in the voltage comparator. The AC transformer in the transformer circuit is a high-precision voltage transformer with a response speed within 20μs. The second resistor can reduce interference caused by input fluctuations. The full-bridge rectification composed of four ultra-low reverse leakage diodes improves efficiency by 100% compared to half-wave rectification. A COG filter capacitor with a good temperature coefficient is used to avoid the signal collected by the filter capacitor being affected by the environment. The detection circuit can control the protection logic action time within 10ms, enabling the transformer circuit to respond quickly.

Description

Technical Field

[0001] This utility model belongs to the field of power failure detection technology, specifically relating to a rapid detection circuit for airborne AC power failure. Background Technology

[0002] Power failure detection is a protective measure to prevent damage to critical components, electromagnetic interference, and malfunctions of related equipment caused by a sudden drop in output voltage when the power supply to the power module is disconnected. A common detection method is the AC Good Sing (AC-GD) signal detection method. This method generates its signal internally within the power module to monitor the input voltage status. While it offers fast signal response, it requires a storage capacitor to maintain the detection loop's normal operation. According to the formula for calculating the storage capacitor: P*t=0.5C*(Vi²-Vm²), larger capacitors are needed for higher power outputs. However, large-capacity capacitors are bulky, resulting in low space utilization for the AC-GD method. Another detection method involves rectifying the input AC power to DC power and then detecting it via an optocoupler. The detection time of this method depends on the peak, trough, or zero-crossing point of the AC input waveform at the moment of power failure, leading to a wide fluctuation range and poor consistency. Utility Model Content

[0003] The purpose of this invention is to provide an airborne AC power failure rapid detection circuit. An operational amplifier, voltage comparator, and linear regulator are connected to the downstream of the transformer circuit. The AC transformer in the transformer circuit is a high-precision voltage transformer with a response speed within 20μs. The second resistor reduces interference caused by input fluctuations. The full-bridge rectifier composed of four ultra-low reverse leakage diodes improves efficiency by nearly 100% compared to half-wave rectification. A COG filter capacitor with a good temperature coefficient is used to avoid the signal collected by the filter capacitor being affected by the environment. The detection circuit can control the protection logic action time within 10ms, enabling the transformer circuit to respond quickly.

[0004] This utility model is achieved through the following technical solution: A rapid detection circuit for airborne AC power failure includes a transformer circuit, an operational amplifier, a voltage comparator, and a linear regulator. The transformer circuit is connected to the operational amplifier, and the voltage comparator is connected to both the linear regulator and the operational amplifier. The transformer circuit rectifies high-voltage AC power into low-voltage DC power to obtain an electrical signal. The operational amplifier amplifies the electrical signal and compares it with a reference voltage generated by the linear regulator in the voltage comparator.

[0005] Preferably, the transformer circuit includes a transformer unit, an anti-interference unit, a rectifier unit, and a filter unit. The anti-interference unit is located between the transformer unit and the rectifier unit, and the filter unit is connected to the rear end of the rectifier unit. The filter unit is used to convert low-voltage DC power into an electrical signal.

[0006] Preferably, the transformer unit includes a first resistor and an AC transformer, with one end of the first resistor connected to the high-voltage AC input terminal and the other end connected to the AC transformer.

[0007] Preferably, the anti-interference unit includes a second resistor, which is connected in parallel with the AC transformer.

[0008] Preferably, the rectifier unit includes a first diode group and a second diode group, the first diode group is located between the second diode group and the second resistor, the first diode group is connected in parallel with the second diode group and the second resistor, and the filter unit is connected to the first diode group and the second diode group.

[0009] Preferably, the first diode group includes a first rectifier diode and a second rectifier diode, the anode of the first rectifier diode is connected to one end of a second resistor, the anode of the second rectifier diode is connected to the other end of a second resistor, and the cathodes of the first rectifier diode and the second rectifier diode are connected in series.

[0010] Preferably, the second diode group includes a third rectifier diode and a fourth rectifier diode, wherein the anode of the third rectifier diode is connected in series with the anode of the fourth rectifier diode.

[0011] Preferably, the filtering unit includes a filtering capacitor, one end of which is connected between the first rectifier diode and the second rectifier diode, and the other end of which is connected between the third rectifier diode and the fourth rectifier diode. The filtering capacitor is connected to ground and the operational amplifier.

[0012] Compared with the prior art, this utility model has the following advantages and beneficial effects: 1) In this utility model, an operational amplifier, a voltage comparator, and a linear regulator are connected to the back end of the transformer circuit. The AC transformer in the transformer circuit is a high-precision voltage transformer with a response speed within 20μs. The second resistor can reduce the interference caused by input fluctuations. The full-bridge rectifier composed of four ultra-low reverse leakage diodes improves the efficiency by 1 times compared to half-wave rectification. A COG filter capacitor with a good temperature coefficient is used to avoid the signal collected by the filter capacitor being affected by the environment. The detection circuit can control the protection logic action time within 10ms, enabling the transformer circuit to respond quickly.

[0013] 2) In this utility model, the AC transformer transmits signals through coupling, and there is no direct electrical connection between the primary and secondary sides, which completely avoids the risk of high voltage entering the low voltage control circuit. The magnetic saturation characteristic of the iron core can absorb the primary surge voltage and resist transient interference. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the airborne AC power supply failure rapid detection circuit in this utility model.

[0016] Where: R1 - first resistor, T - AC transformer, R2 - second resistor, D1 - first rectifier diode, D2 - second rectifier diode, D3 - third rectifier diode, D4 ​​- fourth rectifier diode, C - filter capacitor, U1 - operational amplifier, U2 - linear regulator, U3 - comparator. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0018] Example 1: A rapid detection circuit for airborne AC power failure, such as Figure 1As shown, the system includes a transformer circuit, operational amplifier U1, voltage comparator U3, and linear regulator U2. The transformer circuit is connected to operational amplifier U1, and voltage comparator U3 is connected to both linear regulator U2 and operational amplifier U1. The transformer circuit rectifies high-voltage AC power into low-voltage DC power to obtain the electrical signal V-TEST. Operational amplifier U1 can boost the amplitude of the low-voltage DC voltage to a specified value. After amplifying the electrical signal V-TEST, operational amplifier U1 compares it with the reference voltage generated by linear regulator U2 in voltage comparator U3. The reference voltage generated by linear regulator U2 is 4.4V. If the value of the electrical signal is greater than that of linear regulator U2... When the reference voltage is 4.4V, the power supply is determined to be disconnected. At this time, comparator U3 will generate and output a voltage shutdown signal V-CTRL to control the shutdown MOSFET at the output terminal to achieve rapid power-off of the output and protect the downstream circuit. The transformer circuit includes a transformer unit, an anti-interference unit, a rectifier unit, and a filter unit. The anti-interference unit is located between the transformer unit and the rectifier unit, and the filter unit is connected to the rear end of the rectifier unit. The transformer unit couples high-voltage AC to low-voltage AC. The anti-interference unit can reduce the interference caused by input fluctuations. The rectifier bridge composed of the rectifier unit rectifies the low-voltage AC to low-voltage DC. The filter unit is used to convert the low-voltage DC into the electrical signal V-TEST.

[0019] Example 2: This embodiment, based on the above embodiment, further defines the transformer circuit. The transformer unit includes a first resistor R1 and an AC transformer T. The first resistor R1 acts as a voltage divider resistor to balance the voltage across the AC transformer T. The AC transformer T is a high-precision voltage transformer with a response speed within 20μs. One end of the first resistor R1 is connected to the high-voltage AC input terminal of the power module, and the other end is connected to the AC transformer T. The anti-interference unit includes a second resistor R2, which is connected in parallel with the AC transformer T. The second resistor R2 can reduce the interference caused by input fluctuations. The rectifier unit includes a first diode group and a second diode group. The first diode group is located between the second diode group and the second resistor R2. The first diode group is connected in parallel with the second diode group and the second resistor R2. The filter unit is connected in parallel with the first diode group and the second resistor R2. A diode group and a second diode group are connected. The first diode group includes a first rectifier diode D1 and a second rectifier diode D2. The anode of the first rectifier diode D1 is connected to one end of the second resistor R2, and the anode of the second rectifier diode D2 is connected to the other end of the second resistor R2. The cathodes of the first rectifier diode D1 and the second rectifier diode D2 are connected in series. The second diode group includes a third rectifier diode D3 and a fourth rectifier diode D4. The anodes of the third rectifier diode D3 and the fourth rectifier diode D4 are connected in series. The first rectifier diode D1, the second rectifier diode D2, the third rectifier diode D3, and the fourth rectifier diode D4 are all ultra-low reverse leakage diodes. The rectifier bridge formed by the four ultra-low reverse leakage diodes can rectify the AC power at the front end into DC power. The actual application scenarios of the detection circuit have a wide temperature range, usually between -55℃ and +105℃. Although the traditional Schottky diode has a low rectified voltage, it has a large reverse leakage current in low current detection applications. At high temperatures, the leakage current of the traditional diode increases, and the rectified detection circuit will fail as the temperature rises. Therefore, ultra-low reverse leakage current diodes are used to avoid the problem of detection circuit failure.

[0020] The filtering unit includes a filter capacitor C, which is a COG ceramic capacitor. C has extremely high stability and low loss characteristics, ensuring a fast response from the detection circuit while filtering. The detection circuit uses full-wave rectification, requiring a suitable filter capacitor C. Full-wave rectification reduces DC ripple after rectification; a larger output rectifier capacitor results in smaller DC ripple, improving the accuracy of AC power failure detection. However, a larger rectifier capacitor leads to a longer voltage drop time for the filter capacitor C after AC power failure, resulting in a longer detection time. Therefore, the capacitance of the filter capacitor C cannot be too large and must be selected in conjunction with the downstream operational amplifier comparator circuit to avoid slow voltage drop affecting the judgment speed. Since the COG ceramic capacitor capacitance cannot be too large, and operational amplifier compression and saturation amplification are used, the detection comparison thresholds for different input ranges can be standardized.

[0021] One end of the filter capacitor C is connected between the first rectifier diode D1 and the second rectifier diode D2, and the other end is connected between the third rectifier diode D3 and the fourth rectifier diode D4. The filter capacitor C is connected to ground and operational amplifier U1. The electrical signal V-TEST generated by the filter capacitor C enters operational amplifier U1, is amplified, and then enters comparator U3 to compare with the reference voltage generated by linear regulator U2 to determine whether the power module is powered off, thereby determining whether to output a shutdown signal to protect the back-end circuit. In the actual detection process, the operational amplifier compresses and saturates the DC with a certain ripple before sending it to the comparator. This allows for the use of a comparison threshold for both the lowest and highest voltages when the AC input amplitude changes, such as when it changes by 115VAC±20%. This method is more reliable and faster than the traditional method of using the lowest voltage as the reference threshold. The other parts of this embodiment are the same as those in the above embodiment and will not be repeated here.

[0022] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use. They are only used to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this utility model does not imply that the components are required to be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0025] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. An on-board AC power supply outage quick detection circuit, characterized by, The system includes a transformer circuit, an operational amplifier, a voltage comparator, and a linear regulator. The transformer circuit is connected to the operational amplifier, and the voltage comparator is connected to both the linear regulator and the operational amplifier. The transformer circuit rectifies high-voltage AC power into low-voltage DC power to obtain an electrical signal. The operational amplifier amplifies the electrical signal and compares it with a reference voltage generated by the linear regulator in the voltage comparator. The AC transformer in the transformer circuit is a high-precision voltage transformer. The transformer circuit includes a transformer unit, an anti-interference unit, a rectifier unit, and a filter unit. The anti-interference unit is located between the transformer unit and the rectifier unit, and the filter unit is connected to the rear end of the rectifier unit. The filter unit is used to convert low-voltage DC power into an electrical signal. The transformer unit includes a first resistor and an AC transformer. One end of the first resistor is connected to the high-voltage AC input terminal, and the other end is connected to the AC transformer. The anti-interference unit includes a second resistor, which is connected in parallel with the AC transformer. The rectifier unit includes a first diode group and a second diode group. The first diode group is located between the second diode group and the second resistor. The first diode group is connected in parallel with the second diode group and the second resistor. The filter unit is connected to the first diode group and the second diode group. The first diode group includes a first rectifier diode and a second rectifier diode. The anode of the first rectifier diode is connected to one end of a second resistor, and the anode of the second rectifier diode is connected to the other end of the second resistor. The cathodes of the first rectifier diode and the second rectifier diode are connected in series. The second diode group includes a third rectifier diode and a fourth rectifier diode. The anodes of the third rectifier diode and the fourth rectifier diode are connected in series. The first rectifier diode, the second rectifier diode, the third rectifier diode, and the fourth rectifier diode are all the same ultra-low reverse leakage diode.

2. The on-board AC power supply outage quick detection circuit of claim 1, wherein, The filtering unit includes a filtering capacitor. One end of the filtering capacitor is connected between the first rectifier diode and the second rectifier diode, and the other end of the filtering capacitor is connected between the third rectifier diode and the fourth rectifier diode. The filtering capacitor is connected to ground and the operational amplifier.

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