A power-down detection circuit and device

Abstract

The application discloses a power-off detection circuit and equipment, wherein the power-off detection circuit comprises a filter circuit, a rectifier circuit, an operational amplifier circuit and a comparison circuit; the filter circuit is used for filtering an input alternating current signal; the rectifier circuit is connected with the filter circuit and is used for rectifying the filtered alternating current signal to output a first voltage signal; the operational amplifier circuit is used for amplifying the first voltage signal to output a second voltage signal; and the comparison circuit is used for comparing the input second voltage signal with a reference voltage signal to output level indication information. The application reduces the output voltage by using the filter circuit at the alternating current input end, increases the isolation capacity, uses the rectifier circuit to stabilize the waveform, reduces the waveform fluctuation range, uses the operational amplifier circuit to amplify the voltage signal, improves the precision and sensitivity, and finally uses the comparison circuit to output the level indication information, so that the voltage abnormal condition can be accurately and quickly detected.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more specifically, to a power failure detection circuit and device. Background Technology

[0002] With the continuous development of information and electronic technology, in AC-powered electronic equipment systems, especially in some important power-consuming situations, the requirements for the stability of AC power supply are becoming increasingly higher. To ensure the stability of the equipment, it is necessary to ensure that the power system can quickly detect the occurrence of power grid failure.

[0003] However, some current power failure detection circuits often require multiple power frequency cycles to accurately detect power failures. Although the time is very short, it is still insufficient for some devices with special power supply requirements, leading to system instability. In some cases, abnormal power failures can cause file or data corruption, affecting boot times or causing data loss, which greatly impacts the user experience. Summary of the Invention

[0004] To address the aforementioned issues, embodiments of this application provide a power failure detection circuit and device.

[0005] In a first aspect, embodiments of this application provide a power-down detection circuit, which includes: a filter circuit, a rectifier circuit, an operational amplifier circuit, and a comparator circuit;

[0006] The filtering circuit is used to filter the input AC signal.

[0007] The rectifier circuit is connected to the filter circuit and is used to rectify the filtered AC signal and output a first voltage signal.

[0008] The operational amplifier circuit is used to amplify the first voltage signal and output a second voltage signal.

[0009] The comparison circuit is used to compare the input second voltage signal and the reference voltage signal, and output indication level information.

[0010] Preferably, it also includes a protection circuit located between the filter circuit and the rectifier circuit;

[0011] The protection circuit includes a current-limiting resistor and a current-type voltage transformer, used to reduce the voltage corresponding to the AC signal input to the rectifier circuit.

[0012] Preferably, the rectifier circuit includes a rectifier bridge, an intermediate resistor, and an intermediate capacitor;

[0013] The rectifier bridge is used to rectify the filtered AC signal.

[0014] The intermediate resistor is used to perform current-to-voltage conversion and output an intermediate voltage signal;

[0015] The intermediate capacitor is used to regulate the intermediate voltage signal and output a first voltage signal.

[0016] Preferably, the input terminal of the operational amplifier circuit is coupled to the output terminal of the rectifier circuit, which is used to amplify the amplitude of the first voltage signal to a preset multiple and output the second voltage signal.

[0017] Preferably, the preset multiplier corresponding to the operational amplifier circuit satisfies a preset mapping relationship with the intermediate resistor and the intermediate capacitor.

[0018] Preferably, if the indicator level information output by the comparison circuit is high, and the high level is not a square wave, it indicates that the input second voltage signal is greater than the reference voltage signal, and the AC power supply output is normal.

[0019] Preferably, if the indicator level information output by the comparison circuit changes directly from the high level to the low level, it indicates that the input second voltage signal is less than the reference voltage signal, and the AC power supply has lost power.

[0020] Preferably, if the indicator level information output by the comparison circuit is high, and the high level is a square wave, it indicates that the input second voltage signal fluctuates around the reference voltage, and the AC power supply is undervoltage.

[0021] Preferably, if the indicator level information output by the comparison circuit is a square wave and the duty cycle of the square wave gradually decreases, it indicates that the AC power supply is undervoltage or power failure.

[0022] Secondly, embodiments of this application provide a power failure detection device, including the power failure detection circuit described in any of the first aspects.

[0023] The beneficial effects of this invention are as follows: by using a filter circuit at the AC input terminal to reduce the output voltage and increase the isolation capability, then using a rectifier circuit to stabilize the waveform and reduce the waveform fluctuation range, and then using an operational amplifier circuit to amplify the voltage signal to improve accuracy and sensitivity, and finally using a comparator circuit to output indicator level information, it is possible to accurately and quickly detect abnormal voltage conditions, and then notify the processor to perform relevant data processing by means of a hardware interrupt, so as to prevent the device from malfunctioning due to abnormal power loss. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a power-down detection circuit provided in an embodiment of this application;

[0026] Figure 2 This is a circuit diagram of a power-down detection circuit provided in an embodiment of this application. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0028] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The following description provides multiple embodiments of this application, which can be substituted or combined with each other. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0029] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0030] To better understand this invention, the meanings of the terms used in this document will be explained before describing the invention.

[0031] A power outage is a situation that occurs when a photovoltaic inverter is powered on DC but not AC. In this application, a power outage refers to a situation where electrical equipment cannot function properly due to a power failure, loss of power, or insufficient power quality, such as the AC power supply ceasing to output voltage.

[0032] Filtering is the process of removing specific frequency bands from a signal, and it is an important measure to suppress and prevent interference. A filter can be a circuit that allows only signal components within a certain frequency range to pass through while blocking other frequency components, or it can use the frequency characteristics of a circuit to select the frequency components in a signal.

[0033] Rectification is the process of converting alternating current (AC) into direct current (DC).

[0034] See Figure 1 , Figure 1 This is a schematic diagram of a power-down detection circuit provided in an embodiment of this application. In this embodiment, the power-down detection circuit includes: a filter circuit 110, a rectifier circuit 120, an operational amplifier circuit 130, and a comparator circuit 140.

[0035] The filter circuit 110 is used to filter the input AC signal;

[0036] The rectifier circuit 120 is connected to the filter circuit 110 and is used to rectify the filtered AC signal and output the first voltage signal.

[0037] The operational amplifier circuit 130 is used to amplify the first voltage signal and output the second voltage signal;

[0038] The comparator circuit 140 is used to compare the input second voltage signal and the reference voltage signal, and output indication level information.

[0039] In this embodiment, the AC power is filtered by the filter circuit 110, reducing high-frequency interference signals in the AC signal. The output terminal of the filter circuit 110 is coupled to the input terminal of the rectifier circuit 120. The filtered AC signal is converted into a DC signal by the rectifier circuit 120, and a first voltage signal is output to the operational amplifier circuit 130. The operational amplifier circuit 130 can amplify the input first voltage signal to a preset factor and output a second voltage signal.

[0040] In one example, the reference voltage signal is 183V. If the output second voltage signal is less than 183V, the comparator circuit 140 outputs a first indication level information; if the output second voltage signal is not less than 183V, the comparator circuit 140 outputs a second indication level information. Here, the first indication level information and the second indication level information can be different types of indication levels.

[0041] It should be noted that the indication level information may include not only the first and second indication level information, but also other types of indication level information, which are used to indicate different AC power conditions at the output terminal. When an abnormality occurs in the AC power at the output terminal, the second voltage signal input to the comparator circuit 140 will change accordingly, and this change will be reflected in the indication level information. Therefore, the specific abnormality of the output voltage can be accurately and quickly determined, and a processing strategy can be rapidly formulated to reduce losses caused by voltage abnormalities.

[0042] In one possible implementation, a protection circuit located between the filter circuit and the rectifier circuit is also included;

[0043] The protection circuit includes a current-limiting resistor and a current-type voltage transformer, which are used to reduce the voltage corresponding to the AC signal input to the rectifier circuit.

[0044] In this embodiment, the current-limiting resistor is used to limit the magnitude of the current in the circuit to prevent damage to other electrical components. Its specific resistance value can be determined based on factors such as allowable power consumption, circuit voltage, current, resistor accuracy, and temperature coefficient, and is not limited here.

[0045] In one possible implementation, the rectifier circuit 120 includes a rectifier bridge, an intermediate resistor, and an intermediate capacitor;

[0046] A rectifier bridge is used to rectify filtered AC signals.

[0047] The intermediate resistor is used for current-to-voltage conversion to output an intermediate voltage signal.

[0048] The intermediate capacitor is used to regulate the intermediate voltage signal and output the first voltage signal.

[0049] The principle of a rectifier bridge is to use the unidirectional conductivity of diodes to convert alternating current (AC) into pulsating direct current (DC). A rectifier bridge can consist of four diodes, each with forward conduction and reverse cutoff characteristics to achieve rectification. When AC current is forward-clamped through the rectifier bridge, current can be emitted through the diodes to the reverse clamp, forming a reverse current, thus forming a complete rectifier bridge. The intermediate resistor acts as a sampling resistor, converting the current signal into a voltage signal. The voltage drop across the intermediate resistor is proportional to the resistance value; that is, the smaller the resistance value, the smaller the voltage drop. Therefore, the smaller the intermediate resistor, the faster the detection speed. The intermediate capacitor has the ability to store and release charge. When the input voltage increases, the intermediate capacitor stores more charge, causing its voltage to rise. When the voltage exceeds a preset value, the voltage regulator circuit reduces the current by adjusting the corresponding resistor, thereby limiting the charge storage in the intermediate capacitor and preventing the voltage from rising further. When the input voltage decreases, the intermediate capacitor releases charge, causing its voltage to drop.

[0050] In one possible implementation, the input terminal of the operational amplifier circuit 130 is coupled to the output terminal of the rectifier circuit to amplify the amplitude of the first voltage signal to a preset multiple and output the second voltage signal.

[0051] As described in the above embodiments, considering the detection speed, the resistance value of the intermediate resistor will not be very large, and therefore, the voltage value of the output first voltage signal will not be very large either. Here, the amplitude of the first voltage signal is amplified by an operational amplifier circuit to output a second voltage signal of normal magnitude.

[0052] In one possible implementation, the preset multiplier corresponding to the operational amplifier circuit 130 satisfies a preset mapping relationship with the intermediate resistor and the intermediate capacitor.

[0053] In this embodiment, the intermediate resistor and capacitor utilize the voltage divider principle; the smaller the resistance value, the smaller the voltage division ratio. Therefore, by adjusting the values ​​of the intermediate resistor and capacitor to a preset multiple corresponding to the operational amplifier circuit, the actual voltage of the current circuit can be output.

[0054] In one example, voltage sampling is performed through an intermediate resistor, with the sampling expected to be one-fifth of the circuit voltage. Correspondingly, the preset multiplier of the operational amplifier circuit is 5. Thus, the output second voltage signal can reflect the true voltage of the current circuit, thereby ensuring an accurate voltage signal output while ensuring a fast detection speed.

[0055] In one possible implementation, if the indicator level information output by the comparator circuit is high, and the high level is not a square wave, it indicates that the input second voltage signal is greater than the reference voltage signal, and the AC power supply output is normal.

[0056] In digital circuits, high and low voltage levels typically represent logic "1" and logic "0," respectively. Specifically, a high level indicates that a signal or state is on or activated, while a low level indicates that a signal or state is off or inactive. The output signal of a power-down detection circuit also follows this rule. When the power supply is working normally, the output signal of the power-down detection circuit is high; when the power supply malfunctions or loses power, the output signal becomes low. Here, if the comparator circuit outputs a high level indicator, and this high level is not a square wave, it indicates that the AC power supply output is normal.

[0057] In one possible implementation, if the indicator level information output by the comparator circuit changes directly from high level to low level, it indicates that the input second voltage signal is less than the reference voltage signal, and the AC power supply is cut off.

[0058] In this embodiment, when the AC power supply fails, the voltage on both sides of the intermediate resistor and the second voltage signal output by the operational amplifier circuit will be lower than the normal voltage, i.e. the reference voltage signal. Therefore, the indication level information output by the comparator circuit will change directly from high level to low level.

[0059] In one possible implementation, if the indicator level information output by the comparator circuit is high, and the high level is a square wave, it indicates that the input second voltage signal fluctuates around the reference voltage, and the AC power supply is undervoltage.

[0060] In this embodiment, when the AC power supply experiences undervoltage, the input signal voltage fluctuates around the reference voltage. Specifically, when the peak value of the fluctuation is greater than the reference voltage and the trough value is less than the reference voltage, the feedback loop in the comparator pulls up the voltage at the non-inverting input, causing the comparator's output to switch from low to high. By continuously switching the output level, a square wave signal is generated. Therefore, if the indication level information output by the comparator circuit is a square wave, and the input second voltage signal fluctuates around the reference voltage, it can be determined that the AC power supply is undervoltage. It should be noted that under normal AC power supply output conditions, the voltage fluctuation trough value is greater than the reference voltage.

[0061] In one possible implementation, if the indicator level information output by the comparison circuit is a square wave and the duty cycle of the square wave gradually decreases, it indicates that the AC power supply is undervoltage or has lost power.

[0062] Duty cycle refers to the proportion of the on-time relative to the total time within a pulse cycle. Here, as the input voltage of the AC power supply continues to decrease, the duty cycle of the square wave gradually decreases until it reaches zero, indicating that the on-time gradually decreases until the square wave becomes completely low. Therefore, if the indicator level information output by the comparator circuit is a square wave, and the duty cycle of the square wave gradually decreases, it can be determined that the AC power supply is undervoltage. When the duty cycle of the square wave decreases to zero, it can be determined that the AC power supply has lost power.

[0063] In one specific embodiment, please refer to Figure 2 , Figure 2 This is a circuit diagram of a power failure detection circuit provided in an embodiment of this application. The input electrical signal from the AC power supply passes through... Figure 2The capacitors C1, L1, and C2 in the circuit filter reduce high-frequency interference signals in the electrical signal. The voltage is then reduced by a current-type voltage transformer T1. Using a current-type voltage transformer T1 avoids the impact of varying voltage drops in the rectifier bridge T2 at high and low temperatures on accuracy. R1 acts as a current-limiting resistor for T1. The current output from T1 is rectified by the rectifier bridge T2 and then converted into a voltage signal V1 by resistor R2. Capacitor C3 stabilizes the waveform of the voltage signal V1, minimizing fluctuations and ensuring the minimum voltage approaches the effective value. Furthermore, for rapid detection, R2 and C3 can be set to relatively small values. The voltage across R2 and C3 is amplified by an operational amplifier U1, resulting in an output voltage V2. This voltage is then compared with the reference voltage Vref of comparator U2, and the power-down signal is output to the processor for processing.

[0064] When AC power fails, the voltage across C3 discharges through R2, causing the output voltage V2 of op-amp U1 to decrease. When V2 drops below the reference voltage, the comparator output changes from high to low. At this point, the control unit MCU can determine that AC power has failed and perform relevant processing. Simultaneously, the sensitivity can be adjusted by changing the values ​​of R2 and C3 and the amplification factor of op-amp U1.

[0065] When there is no AC power loss but undervoltage, the lowest point of the voltage waveform V1 across capacitor C3 decreases. At this time, when the lowest point V2 of the output voltage of op-amp U1 is lower than the reference voltage of comparator U2, a square wave is output. As the AC voltage continues to decrease, the duty cycle of the square wave gradually decreases until it becomes completely low. Here, different duty cycles can be flexibly selected to determine whether there is undervoltage or power loss according to the sensitivity requirements; there is no specific limitation.

[0066] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0067] In one possible implementation, this application also provides a power failure detection device, which includes a power failure detection circuit as described in any of the preceding claims.

[0068] This application embodiment reduces the output voltage and increases isolation capability by using a filter circuit at the AC input terminal, stabilizes the waveform and reduces the waveform fluctuation range by using a rectifier circuit, amplifies the voltage signal by using an operational amplifier circuit to improve accuracy and sensitivity, and finally uses a comparator circuit to output indicator level information, thereby enabling accurate and rapid detection of voltage anomalies.

[0069] In one possible implementation, this application embodiment also provides a power failure detection method, which includes the following steps:

[0070] Obtain the first sampled voltage;

[0071] The first sampled voltage is amplified to obtain the second sampled voltage;

[0072] The second sampled voltage is input to the comparator for comparison, and the indication level information output by the comparator is obtained.

[0073] It should be noted that the sampling voltage here can be obtained by sampling the filtered and rectified power supply voltage through a sampling resistor. The specific sampling process can be referred to the above embodiment, and will not be repeated here. Based on the indication level information, voltage anomalies can be detected accurately and quickly. That is, if the indication level information output by the comparator circuit is high, and the high level is not a square wave, it indicates that the input second voltage signal is greater than the reference voltage signal, and the AC power supply output is normal. If the indication level information output by the comparator circuit changes directly from high to low, it indicates that the input second voltage signal is less than the reference voltage signal, and the AC power supply has lost power. If the indication level information output by the comparator circuit is high, and the high level is a square wave, or the indication level information output by the comparator circuit gradually changes from a square wave to a low level, it indicates that the input second voltage signal is less than the reference voltage signal, and the AC power supply is undervoltage.

[0074] This section only shows the parts relevant to the embodiments of this application. For specific technical details not disclosed, please refer to this application. Figure 1 and Figure 2 The example shown.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed circuits and devices can be implemented in other ways. For example, multiple units or components can be combined or integrated into another system, or some features can be omitted or not performed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed can be indirect coupling or communication connection through some service interface, device, or unit, and can be electrical or other forms.

[0076] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0077] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A power-down detection circuit, characterized in that, include: Filtering circuits, rectifier circuits, operational amplifier circuits, and comparator circuits; The filtering circuit is used to filter the input AC signal. The rectifier circuit is connected to the filter circuit and is used to rectify the filtered AC signal and output a first voltage signal. The operational amplifier circuit is used to amplify the first voltage signal and output a second voltage signal. The comparison circuit is used to compare the input second voltage signal and the reference voltage signal, and output indication level information; The power failure detection circuit also includes a protection circuit located between the filter circuit and the rectifier circuit; The protection circuit includes a current-limiting resistor and a current-type voltage transformer, used to reduce the voltage corresponding to the AC signal input to the rectifier circuit; The rectifier circuit includes a rectifier bridge, an intermediate resistor, and an intermediate capacitor. The rectifier bridge is used to rectify the filtered AC signal. The intermediate resistor is used to perform current-to-voltage conversion and output an intermediate voltage signal; The intermediate capacitor is used to regulate the intermediate voltage signal and output a first voltage signal. The input terminal of the operational amplifier circuit is coupled to the output terminal of the rectifier circuit, and is used to amplify the amplitude of the first voltage signal to a preset multiple and output the second voltage signal. The preset multiplier corresponding to the operational amplifier circuit satisfies a preset mapping relationship with the intermediate resistor and the intermediate capacitor; If the indicator level information output by the comparison circuit is high, and the high level is not a square wave, it indicates that the input second voltage signal is greater than the reference voltage signal, and the AC power supply output is normal. If the indicator level information output by the comparison circuit changes directly from high level to low level, it indicates that the input second voltage signal is less than the reference voltage signal, and the AC power supply is lost. If the indicator level information output by the comparison circuit is high, and the high level is a square wave, it indicates that the input second voltage signal fluctuates around the reference voltage, and the AC power supply is undervoltage. If the indicator level information output by the comparison circuit is a square wave, and the duty cycle of the square wave gradually decreases, it indicates that the AC power supply is undervoltage or has lost power.

2. A power failure detection device, characterized in that, Includes the power failure detection circuit according to claim 1.

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