A power grid voltage power failure detection circuit and power failure detection method

Abstract

The present invention relates to the field of power electronic technology, and provides a power grid voltage power failure detection circuit and a power failure detection method. The present invention converts alternating current into a steamed wave voltage through a rectifier bridge circuit, and processes the steamed wave voltage through multiple unit circuits in a signal processing circuit. Specifically, the steamed wave voltage is compared with a reference voltage through a comparator. When the current voltage of the steamed wave voltage is greater than the reference voltage, the comparator outputs a high level to a pulse generator, and the pulse generator generates a pulse signal and sends it to a counter. The counter counts the pulse signals sent by multiple units in the signal processing circuit, and then can judge whether the power grid is powered off according to the statistical results of the counter. The present invention only requires hardware to realize power failure detection. At the same time, the power grid voltage power failure detection circuit that performs power failure detection through a comparator, a pulse generator and a counter can accurately detect whether the power grid voltage is powered off within half an alternating current cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a power grid voltage power failure detection circuit and a power failure detection method. Background Art

[0002] With the continuous development of information electronic technology, in AC-powered electronic equipment systems, especially in some important power-consuming occasions, the requirements of power-consuming equipment for AC power supply stability are getting higher and higher. To ensure the stability of power-consuming equipment, it is necessary to ensure that the power-consuming system can quickly detect the occurrence of power outages in the power grid. When the power grid is out of power, it is difficult to maintain the system operation by relying solely on the DC bus energy. If the power-consuming equipment is to be guaranteed not to be powered off, the system needs to quickly detect the power outage in a short time and switch the backup power supply to the power-consuming equipment to power the equipment to ensure that the system is always in working condition. Some traditional power-off detection circuits output a pulse signal once in half a power frequency cycle to indicate that the power grid has been powered off. In this case, it is difficult to accurately detect the power outage in the power grid within half a power frequency cycle. Generally, multiple power frequency cycles are required to accurately detect the power outage in the power grid. Although the time is very short, for some equipment with special requirements for power supply, the time will still cause power outage problems, which brings instability to the system. Therefore, in order to meet the power-off detection needs of more demanding equipment, it is necessary to further improve the existing power-off detection circuit of the power grid so that the system can more accurately detect the power outage in the power grid within half a power frequency cycle.

[0003] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a power grid voltage power failure detection circuit and a power failure detection method, so as to solve the problems that some traditional power grid power failure detection circuits need multiple power frequency cycles to detect power grid power failure, the power failure detection time is long, and some traditional power failure detection circuits have inaccurate power failure detection.

[0005] In a first aspect, the present invention provides a power grid voltage power failure detection circuit, comprising a rectifier bridge circuit, a signal processing circuit and a counter, wherein the power grid voltage power failure detection circuit is suitable for AC power failure detection, wherein:

[0006] The rectifier bridge circuit is used to connect to the AC power grid and is suitable for rectifying the AC power and outputting a steamed wave voltage;

[0007] The signal processing circuit comprises a plurality of unit circuits, all of which are connected in parallel, and each of which comprises a comparator and a pulse generator;

[0008] The first input terminal of the comparator is coupled to the output terminal of the rectifier bridge circuit, and is suitable for inputting the steamed wave voltage into the comparator; the second input terminal of each comparator is connected to a reference voltage, and is suitable for comparing the current voltage of the steamed wave voltage with the reference voltage, and then determining to output a high level or a low level according to the comparison result; wherein the reference voltage connected to the second input terminal of each comparator is different;

[0009] In each of the unit circuits, the input terminal of the pulse generator is coupled to the output terminal of the comparator, and is adapted to generate a pulse signal according to a high level output by the comparator;

[0010] The input end of the counter is coupled to the output end of the pulse generator, and is suitable for performing statistics on the pulse signal, and judging whether a power outage occurs in the power grid according to the statistical result.

[0011] Furthermore, the grid voltage power failure detection circuit also includes a voltage divider circuit, wherein:

[0012] The input end of the voltage divider circuit is coupled to the output end of the rectifier bridge circuit, and is suitable for reducing the amplitude of the steamed wave voltage, thereby obtaining the steamed wave voltage with a low amplitude;

[0013] The voltage divider circuit includes two voltage divider resistors, and the middle point of the two voltage divider resistors is coupled to the signal processing circuit, so that the signal processing circuit can process the steamed bun wave voltage with low amplitude;

[0014] One end of one of the voltage-dividing resistors is coupled to the output end of the rectifier bridge circuit, and the other end of the voltage-dividing resistor is connected to one end of another voltage-dividing resistor; the other end of the other voltage-dividing resistor is grounded.

[0015] Furthermore, each unit circuit of the signal processing circuit further includes an anti-reverse diode, wherein:

[0016] The input end of the anti-reverse diode is coupled to the output end of the pulse generator, and the output end of the anti-reverse diode is coupled to the input end of the counter.

[0017] Furthermore, a plurality of different reference voltages are preset, the plurality of reference voltages correspond to a plurality of voltages within one cycle of the steamed-wave voltage, and the reference voltage connected to the second input terminal of each comparator is different.

[0018] Furthermore, the counter is adapted to perform statistics on the pulse signal, and determine whether a power outage occurs in the power grid according to the statistical result, wherein:

[0019] The counter is used to count the number of pulse signals to determine whether a power outage occurs in the power grid; within a complete steamed wave voltage cycle, when the steamed wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of the reference voltage, it is determined that a power outage occurs in the power grid;

[0020] Alternatively, the counter is used to count the time intervals of pulse signal transmissions, and when the time intervals do not meet preset requirements, it is determined that a power outage occurs in the power grid.

[0021] Furthermore, the counter is adapted to perform statistics on the pulse signal, and determine whether a power outage occurs in the power grid according to the statistical result, wherein:

[0022] The counter is set with a target pulse number, and the counter is used to determine whether a power outage occurs in the power grid based on the target pulse number and the counted number of pulse signals. When the number of pulse signals counted by the counter is less than the target pulse number, it is determined that a power outage occurs in the power grid.

[0023] Further, the pulse generator is adapted to generate a pulse signal according to the high level output by the comparator, wherein:

[0024] When the comparator transmits a high level to the pulse generator, the pulse generator detects the rising edge of the high level and immediately starts to generate a pulse signal, so as to ensure that each of the pulse generators generates only one pulse signal within a period of the steamed wave voltage;

[0025] The pulse signal generated by the pulse generator is a narrow pulse, and the starting point of the narrow pulse is located in the first half cycle of the steamed bun wave voltage.

[0026] In a second aspect, the present invention further provides a method for detecting power failure of a power grid voltage. The method for detecting power failure of a power grid voltage is based on the power grid voltage power failure detection circuit of the first aspect and is used for detecting power failure of a power grid, comprising:

[0027] The rectifier bridge circuit rectifies the alternating current and outputs a steamed wave voltage;

[0028] The comparator compares the current voltage of the steamed-wave voltage with the reference voltage connected to the comparator, and then determines to output a high level or a low level according to the comparison result;

[0029] The pulse generator generates a pulse signal according to the high level output by the comparator;

[0030] The input end of the counter is coupled to the output end of the pulse generator, and is suitable for performing statistics on the pulse signal, and judging whether a power outage occurs in the power grid according to the statistical result.

[0031] Furthermore, the counter performs statistics on the pulse signal, and judging whether a power outage occurs in the power grid according to the statistical result includes:

[0032] The counter counts the number of pulse signals to determine whether a power outage occurs in the power grid; within a complete steamed-wave voltage cycle, when the steamed-wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of the reference voltage, it is determined that a power outage occurs in the power grid;

[0033] Alternatively, the counter is set with a target pulse number, and when the number of pulse signals counted by the counter is less than the target pulse number, it is determined that a power outage occurs in the power grid.

[0034] Furthermore, the counter performs statistics on the pulse signal, and judging whether a power outage occurs in the power grid according to the statistical result includes:

[0035] The counter counts the time intervals between pulse signal transmissions, and when the next pulse signal is not received within a preset time interval, it is determined that a power outage has occurred in the power grid.

[0036] The embodiment of the present invention converts AC power into a steamed-wave voltage through a rectifier bridge circuit, and processes the steamed-wave voltage through multiple unit circuits in a signal processing circuit. Specifically, the steamed-wave voltage is compared with a reference voltage through a comparator. When the current voltage of the steamed-wave voltage is greater than the reference voltage, the comparator outputs a high level to the pulse generator, and the pulse generator generates a pulse signal and sends it to a counter. The counter counts the pulse signals sent by multiple units in the signal processing circuit, and can then determine whether the power grid is powered off according to the statistical results of the counter. The power grid voltage power-off detection circuit provided by the embodiment of the present invention is a power grid voltage power-off detection circuit that performs power-off detection through a comparator, a pulse generator, and a counter, and can accurately detect whether the power grid voltage is powered off within half an AC power cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1a It is a circuit diagram of a power grid voltage drop detection circuit provided by an embodiment of the present invention;

[0039] Figure 1b It is a circuit diagram of another grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0040] Figure 2It is a schematic diagram comparing an alternating current voltage waveform and a steamed-wave voltage waveform provided by an embodiment of the present invention;

[0041] Figure 3 This is a first principle schematic diagram of power failure detection of a power grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0042] Figure 4 It is a second principle schematic diagram of power failure detection of a power grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0043] Figure 5 It is a third principle schematic diagram of power failure detection of a power grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0044] Figure 6 It is a fourth principle schematic diagram of power failure detection of a power grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0045] Figure 7 It is a seventh principle schematic diagram of power failure detection of a power grid voltage power failure detection circuit provided by an embodiment of the present invention;

[0046] Figure 8 The present invention is a flowchart of a method for detecting power failure of a power grid provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] In the description of the present invention, the terms "inside", "outside", "longitudinal", "lateral", "upper", "lower", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0049] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0050] Embodiment 1:

[0051] Embodiment 1 of the present invention provides a power grid voltage drop detection circuit, such as Figure 1a As shown, it includes a rectifier bridge circuit, a signal processing circuit and a counter, and the grid voltage power failure detection circuit is suitable for AC grid power failure detection.

[0052] The rectifier bridge circuit is used to connect to the AC power grid and is suitable for rectifying the AC power and outputting a steamed wave voltage.

[0053] The signal processing circuit includes a plurality of unit circuits, all of which are connected in parallel, and each of which includes a comparator and a pulse generator.

[0054] The first input terminal of the comparator is coupled to the output terminal of the rectifier bridge circuit, and is suitable for inputting the steamed bun wave voltage into the comparator; the second input terminal of each comparator is connected to a reference voltage, and is suitable for comparing the current voltage of the steamed bun wave voltage with the reference voltage, and then determining the output high level or low level according to the comparison result; wherein, the reference voltage connected to the second input terminal of each comparator is different.

[0055] In each unit circuit, the input end of the pulse generator is coupled to the output end of the comparator, and is suitable for generating a pulse signal according to the high level output by the comparator.

[0056] The input end of the counter is coupled to the output end of the pulse generator, and is suitable for counting pulse signals and judging whether a power outage occurs in the power grid according to the statistical results. All the pulse generators input pulse signals into the same counter to count pulse signals.

[0057] The alternating current voltage is rectified by the rectifier bridge circuit to obtain the steamed bun wave voltage, wherein one steamed bun wave voltage cycle is half an alternating current cycle. The waveform diagram of the alternating current voltage and the waveform diagram of the steamed bun wave voltage obtained after rectification by the rectifier bridge circuit are shown in FIG. Figure 2 shown.

[0058] The embodiment of the present invention converts AC power into a steamed-wave voltage through a rectifier bridge circuit, and processes the steamed-wave voltage through multiple unit circuits in a signal processing circuit. Specifically, the steamed-wave voltage is compared with a reference voltage through a comparator. When the current voltage of the steamed-wave voltage is greater than the reference voltage, the comparator outputs a high level to the pulse generator, and the pulse generator generates a pulse signal and sends it to a counter. The counter counts the pulse signals sent by multiple units in the signal processing circuit, and can then determine whether the power grid is powered off according to the statistical results of the counter. The power grid voltage power-off detection circuit provided by the embodiment of the present invention only requires hardware to realize power-off detection. At the same time, the power grid voltage power-off detection circuit that performs power-off detection through a comparator, a pulse generator and a counter can accurately detect whether the power grid voltage is powered off within half an AC power cycle.

[0059] In order to convert the steamed-wave voltage output by the rectifier bridge circuit into a low-amplitude steamed-wave voltage for processing by the signal processing unit, Figure 1bAs shown, the grid voltage power failure detection circuit also includes a voltage divider circuit.

[0060] The input end of the voltage divider circuit is coupled to the output end of the rectifier bridge circuit, and is suitable for reducing the amplitude of the steamed bun wave voltage, thereby obtaining the steamed bun wave voltage with a low amplitude.

[0061] The voltage divider circuit includes two voltage divider resistors, and the middle point of the two voltage divider resistors is coupled to the signal processing circuit so that the signal processing circuit can process the low-amplitude steamed bun wave voltage. One end of one of the voltage divider resistors is coupled to the output end of the rectifier bridge circuit, and the other end of the voltage divider resistor is connected to one end of another voltage divider resistor; the other end of the other voltage divider resistor is grounded.

[0062] by Figure 1b For example, the voltage divider circuit includes voltage divider resistors R1 and R2, the connection point between the voltage divider resistor R1 and the voltage divider resistor R2 is the middle point of the two voltage divider resistors, and the signal processing circuit is coupled to the middle point of the two voltage divider resistors. One end of the voltage divider resistor R1 is coupled to the output end of the rectifier bridge circuit, the other end of the voltage divider resistor R1 is connected to one end of the voltage divider resistor R2, and the other end of the voltage divider resistor R2 is grounded.

[0063] In order to prevent the current from flowing back into each unit circuit of the signal processing unit, each unit circuit of the signal processing circuit further includes an anti-reverse diode, wherein:

[0064] The input end of the anti-reverse diode is coupled to the output end of the pulse generator, and the output end of the anti-reverse diode is coupled to the input end of the counter. The anti-reverse diode is suitable for preventing current from flowing from a pulse generator to another pulse generator, and preventing current from flowing from the counter to the signal processing circuit. Figure 1b For example, diode D1 and diode D2 are anti-reverse diodes.

[0065] In order to perform power-off detection more accurately, in the grid voltage power-off detection circuit, multiple different reference voltages are preset, and the multiple reference voltages correspond to multiple voltages within one cycle of the steamed bun wave voltage. The reference voltage connected to the second input terminal of each comparator is different.

[0066] Specifically, in the first half of the steamed wave voltage cycle, multiple reference voltages are set, and the number of reference voltages is the same as the number of unit circuits of the signal processing unit, that is, each reference voltage corresponds to a certain steamed wave voltage value in the first half of the steamed wave voltage cycle, such as Figure 3As shown, at this time, 10 reference voltage values ​​Ref1 to Ref10 are set in the first half of the steamed wave voltage cycle, corresponding to 10 comparators in the signal processing unit, that is, among these 10 comparators, the reference voltage connected to the second input terminal of each comparator is different.

[0067] Among them, the reason for setting all the reference voltages in the first half of the mantou wave voltage cycle is that, in a mantou wave voltage cycle, the first half cycle and the second half cycle are symmetrical about the central axis, that is, a voltage value in the second half cycle of the mantou wave voltage must be able to find the same value in the first half cycle, and when the comparator compares the reference voltage with the mantou wave voltage, it must first compare the voltage value of the first half cycle of the mantou wave voltage. Therefore, it is not very meaningful to set the reference voltage in the second half cycle of the mantou wave voltage.

[0068] In order to determine whether the power grid is powered off, the counter is suitable for counting the pulse signal, and judging whether the power grid is powered off according to the statistical result, wherein:

[0069] The counter is used to count the number of pulse signals to determine whether a power outage occurs in the power grid; within a complete steamed wave voltage cycle, when the steamed wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of reference voltages, it is determined that a power outage occurs in the power grid; or, the counter is used to count the time interval for pulse signal transmission, and when the time interval does not meet the preset requirements, it is determined that a power outage occurs in the power grid.

[0070] When judging whether the power grid has lost power based on the number of pulse signals, specifically, Figure 3 As shown in the figure, since 10 different reference voltages Ref1 to Ref10 are set, when the steamed wave voltage cycle is halfway through, the counter counts 10 pulse signals, and then determines that the power grid is normal, and then the counter is reset to start the next round of counting. Among them, the second half of the current steamed wave voltage cycle and the first half of the next steamed wave voltage cycle can be used as a counting cycle, such as Figure 2 As shown, a counting cycle is equal to a steamed bun wave voltage cycle or half an AC voltage cycle in time. Setting the counting cycle in this way can ensure that the second half cycle of the steamed bun wave can also be detected, ensuring that the power-off detection is completed within half a cycle of the AC voltage.

[0071] When the power grid loses power, the waveform of the steamed-wave voltage changes, and the number of pulse signals counted by the counter in a counting cycle is less than the preset reference voltage number, then it is determined that the power grid loses power. Figure 3 and Figure 4As shown, in the case where a power outage occurs in the power grid, the counter can only count 7 pulse signals, which is less than the preset reference voltage number 10, and thus it can be determined that a power outage occurs in the power grid.

[0072] A special case is that when the power failure occurs after the last reference voltage comparison is completed, the comparator has emitted a high level, and the pulse generator has received the high level and emitted a pulse signal, the counter will count the number of pulse signals corresponding to the number of reference voltages, so that it is not possible to determine whether the power grid has a power failure in the current counting cycle, and it is not possible to determine whether the power grid has a power failure until the next counting cycle, thereby prolonging the judgment time of the power grid power failure. A solution is to set the last reference voltage as close to the maximum value of the steamed bun wave voltage as possible, that is, the last reference voltage is set as close to the end point of the counting cycle as possible, thereby reducing the probability of this situation occurring.

[0073] Except for the above special circumstances, regardless of whether the power outage occurs in the first half or the second half of the steamed wave voltage cycle, the power grid voltage power outage detection circuit can determine whether the power grid has a power outage within one counting cycle, that is, within half an AC power cycle.

[0074] In an optional embodiment, a complete steamed-wave voltage cycle is used as a counting cycle. At this time, it is equivalent to that the counter starts counting when a steamed-wave voltage cycle starts, and the counter completes counting when a steamed-wave voltage cycle ends, and then judges whether the power grid has a power outage based on the number of pulse signals counted by the counter. The disadvantage of selecting this counting cycle is that in the worst case, that is, when the power outage occurs in the second half of the steamed-wave voltage cycle, since the counter has counted the number of pulse signals that is consistent with the reference voltage number, it is not possible to judge whether the power grid has a power outage in the current counting cycle, and it is necessary to determine whether the power grid has a power outage in the next counting cycle, that is, it takes an AC power cycle to judge whether the power grid has a power outage.

[0075] When judging whether the power grid has lost power based on the time interval, judging whether the power grid has lost power is based on the time interval between multiple signal pulses. Specifically, the reference voltage setting method can also be understood as selecting multiple reference voltages on a steamed wave voltage cycle according to a preset time interval. Therefore, when the power grid does not lose power, the time between the pulse signals is a fixed value. By detecting whether the time interval between the pulse signals meets the preset requirements, it can be judged whether the power grid has lost power. Figure 5As shown, five different reference voltages Ref1 to Ref5 are set. In the steamed wave voltage cycle, the time intervals between the reference voltages are t1 to t5 respectively, starting from the time the counter receives the first pulse signal. If the counter does not receive the next pulse signal after t1 time, it is determined that the power grid has a power outage. If a pulse signal is received, the timing is restarted. If the counter does not receive the next pulse signal after t2 time, it is determined that the power grid has a power outage. If a pulse signal is received, the timing is restarted and waits for the next pulse signal, and so on.

[0076] The method of judging whether the power grid has lost power based on the time interval has the advantage that even in the worst case, it is possible to judge whether the power grid has lost power within half an AC power cycle. When the power grid loses power in the first half of the steamed wave voltage cycle, it is possible to judge whether the power grid has lost power in a very short time. The specific time depends on the setting of the reference voltage, that is, it depends on the preset time between the reference voltages in the steamed wave voltage cycle. Figure 5 As shown in the figure, in the worst case, when the power outage occurs in the t5 time period, it takes t5 time to confirm that the power outage has occurred. When the power outage occurs in the t3 time period, it takes t3 time to confirm that the power outage has occurred. The method of judging whether the power outage has occurred based on the time interval can accurately detect whether the power grid voltage has been lost within half an AC power cycle, meeting the power outage detection requirements of some demanding equipment.

[0077] In order to prevent the power-off detection circuit from misjudging the power-off of the power grid due to power-off distortion, the counter counts the pulse signals, and when judging whether the power grid has lost power based on the statistical results, the counter is provided with a target number of pulses; the counter is used to judge whether the power grid has lost power based on the target number of pulses and the number of pulse signals counted, and when the number of pulse signals counted by the counter is less than the target number of pulses, it is determined that the power grid has lost power.

[0078] Specifically, Figure 7 As shown, when grid distortion occurs, the grid does not lose power, but no anti-misjudgment setting is performed. In one counting cycle, the number of pulse signals counted by the counter is 8, which is less than the number of reference voltages 10. The grid voltage power-off detection circuit will determine that the grid has lost power, which is obviously a misjudgment. Therefore, it is necessary to prevent the power-off detection circuit from misjudging the grid power-off due to grid distortion. In this embodiment, the purpose of anti-misjudgment is achieved by setting a target number of pulses. As long as the number of pulse signals counted by the counter is not less than the target number of pulses, it will not be considered that the grid has lost power. For example, if the target number of pulses is set to 8, Figure 7 In the case of grid distortion as shown, a grid power failure will not be misjudged.

[0079] The setting of the target pulse number is actually a balance between the power failure detection time and the prevention of power failure misjudgment. Under the condition of a certain reference voltage, the smaller the target pulse number is set, the lower the probability of misjudging the power failure in the case of power grid distortion, but the greater the probability of needing multiple counting cycles to detect the power failure. Figure 3 and Figure 4 To illustrate, if the target pulse number is set to 7 and the reference voltage number is 10, Figure 4 In the case shown, the number of pulse signals counted by the counter is 7. In this counting cycle, the grid voltage power-off detection circuit determines that the grid does not power off. It will not detect the power off of the grid until the next counting cycle. In fact, the grid has already power off in this counting cycle. This is obviously a misjudgment. This misjudgment prolongs the power-off detection time. Obviously, the closer the target pulse number is to the reference voltage number, the lower the probability of such misjudgment. However, in the case of grid distortion, the probability of misjudging the grid power off is greater. Therefore, the target pulse number is reasonably set according to the duration of common grid distortion and the power supply demand of electrical equipment.

[0080] In an optional embodiment, when judging whether a power outage has occurred in the power grid based on the time interval, a target time interval can also be set to prevent a misjudgment of a power outage in the power grid when the power grid is distorted. When the pulse counter does not receive a pulse signal within the target time interval, it is judged that a power outage has occurred in the power grid. At this time, the target time interval judgment is not performed during the duration from the last reference voltage of the current steamed wave cycle to the first reference voltage of the next steamed wave cycle. Figure 5 , that is, the target time interval judgment is not performed in the t5 time period, but the power failure detection judgment is also performed in the t5 time period.

[0081] In order to facilitate the counter to count the pulse signal, the pulse generator is suitable for generating a pulse signal according to the high level output by the comparator, such as Figure 6 When the comparator transmits a high level to the pulse generator, the pulse generator detects the rising edge of the high level and immediately starts to generate a pulse signal to ensure that each pulse generator only generates one pulse signal within one cycle of the steamed wave voltage; and the pulse signal generated by the pulse generator is a narrow pulse, and the starting point of the narrow pulse is located in the first half cycle of the steamed wave voltage.

[0082] In a steamed wave voltage cycle, the pulse generator will generate a pulse signal only when it detects the rising edge of the high level, ensuring that the pulse generator can only generate one narrow pulse in a steamed wave cycle, and the pulse generator generates a narrow pulse with a relatively small duty cycle, which can reduce the influence between pulse signals when counting pulse signals, so that the counter can accurately count pulse signals. The grid voltage power-off detection circuit provided by the embodiment of the present invention only needs hardware to realize power-off detection, and the grid voltage power-off detection circuit that performs power-off detection through a comparator, a pulse generator and a counter can accurately detect whether the grid voltage is powered off within half an AC power cycle.

[0083] Embodiment 2:

[0084] Embodiment 2 of the present invention provides a method for detecting power failure of a power grid voltage. The method for detecting power failure of a power grid voltage is based on the power grid voltage power failure detection circuit of the first aspect and is used to detect power failure of a power grid. Figure 8 As shown, including:

[0085] Step 101: the rectifier bridge circuit rectifies the alternating current and outputs a steamed wave voltage;

[0086] Step 102: the comparator compares the current voltage of the steamed wave voltage with the reference voltage connected to the comparator, and then determines to output a high level or a low level according to the comparison result;

[0087] Step 103: the pulse generator generates a pulse signal according to the high level output by the comparator;

[0088] Step 104: the counter performs statistics on the pulse signal, and determines whether the grid voltage has a power failure according to the statistical result.

[0089] The embodiment of the present invention converts AC power into a steamed-wave voltage through a rectifier bridge circuit, and processes the steamed-wave voltage through multiple unit circuits in a signal processing circuit. Specifically, the steamed-wave voltage is compared with a reference voltage through a comparator. When the current voltage of the steamed-wave voltage is greater than the reference voltage, the comparator outputs a high level to the pulse generator, and the pulse generator generates a pulse signal and sends it to a counter. The counter counts the pulse signals sent by multiple units in the signal processing circuit, and can then determine whether the power grid is powered off according to the statistical results of the counter. The power grid voltage power-off detection method provided by the embodiment of the present invention only requires hardware to realize power-off detection. At the same time, power-off detection is performed by a comparator, a pulse generator and a counter, so that it can accurately detect whether the power grid voltage is powered off within half an AC power cycle.

[0090] Specifically, in step 102, multiple reference voltages are set within the first half of the steamed wave voltage cycle, and the number of reference voltages is the same as the number of unit circuits of the signal processing unit, and each reference voltage corresponds to a certain steamed wave voltage value within the first half of the steamed wave voltage cycle, such as Figure 3 As shown, at this time, 10 reference voltage values ​​Ref1 to Ref10 are set in the first half of the steamed wave voltage cycle, corresponding to 10 comparators in the signal processing unit, that is, among these 10 comparators, the reference voltage connected to the second input terminal of each comparator is different.

[0091] In step 103, the pulse generator generates a pulse signal according to the high level output by the comparator, wherein the pulse signal generated by the pulse generator is a narrow pulse to ensure that each pulse generator generates only one pulse signal within a period of the steamed wave voltage. At the same time, when the comparator transmits a high level to the pulse generator, the pulse generator immediately starts to generate the narrow pulse, and the starting point of the narrow pulse is located in the first half period of the steamed wave voltage, so that the counter can count the pulse signal.

[0092] In step 104, the counter counts the pulse signal and determines whether the grid voltage has a power outage based on the statistical results, specifically including: the counter counts the number of pulse signals to determine whether the grid has a power outage, or the counter counts the time interval between pulse signal emissions to determine whether the grid has a power outage.

[0093] Specifically, within a complete steamed-wave voltage cycle, when the steamed-wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of reference voltages, it is determined that a power outage has occurred in the power grid; the counter counts the time interval of pulse signal emission, and when the time interval does not meet the preset requirements, it is determined whether a power outage has occurred in the power grid, or the counter is set with a target number of pulses, and when the number of pulse signals counted by the counter is less than the target number of pulses, it is determined that a power outage has occurred in the power grid. Among them, the time interval of pulse signal emission can be understood as the time interval between the counter receiving adjacent pulse signals.

[0094] When judging whether the power grid has lost power based on the number of pulse signals, specifically, Figure 3 As shown in the figure, since 10 different reference voltages Ref1 to Ref10 are set, when the steamed wave voltage cycle is halfway through, the counter counts 10 pulse signals, and then determines that the power grid is normal, and then the counter is reset to start the next round of counting. Among them, the second half of the current steamed wave voltage cycle and the first half of the next steamed wave voltage cycle are taken as a counting cycle, as shown in the figure. Figure 2As shown, one counting cycle is equal to one steamed bun voltage cycle or half an AC voltage cycle in time.

[0095] When judging whether a power outage occurs in the power grid based on the time interval of pulse signal transmission, judging whether a power outage occurs is based on the time interval between multiple signal pulses, that is, the counter counts the time interval of pulse signal transmission, and when the next pulse signal is not received within the preset time interval, it is determined that a power outage occurs in the power grid.

[0096] Specifically, the reference voltage determination method can also be understood as selecting multiple reference voltages in a steamed wave voltage cycle according to a preset time interval. Therefore, when the power grid is not powered off, the time between the pulse signals is a fixed value. By detecting whether the time interval between the pulse signals meets the preset requirements, it can be determined whether the power grid is powered off. Figure 5 As shown, five different reference voltages Ref1 to Ref5 are set. In the steamed wave voltage cycle, the time intervals between the reference voltages are t1 to t5 respectively, starting from when the counter receives the first pulse signal. If the counter does not receive the next pulse signal after t1 time, it is determined that the power grid has lost power. If a pulse signal is received, the counter will restart the timing. If the counter does not receive the next pulse signal after t2 time, it is determined that the power grid has lost power. If a pulse signal is received, the counter will restart the timing and wait for the next pulse signal, and so on.

[0097] Further supporting explanations on the grid voltage power failure detection method can be specifically combined with the aforementioned embodiment 1, which will not be repeated here.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power grid voltage drop detection circuit, characterized in that: The power grid voltage power failure detection circuit comprises a rectifier bridge circuit, a signal processing circuit and a counter. The power grid voltage power failure detection circuit is suitable for AC power grid power failure detection, wherein: The rectifier bridge circuit is used to connect to the AC power grid and is suitable for rectifying the AC power and outputting a steamed wave voltage; The signal processing circuit comprises a plurality of unit circuits, all of which are connected in parallel, and each of which comprises a comparator and a pulse generator; The first input terminal of the comparator is coupled to the output terminal of the rectifier bridge circuit, and is suitable for inputting the steamed wave voltage into the comparator; the second input terminal of each comparator is connected to a reference voltage, and is suitable for comparing the current voltage of the steamed wave voltage with the reference voltage, and then determining to output a high level or a low level according to the comparison result; wherein the reference voltage connected to the second input terminal of each comparator is different; In each of the unit circuits, the input terminal of the pulse generator is coupled to the output terminal of the comparator, and is adapted to generate a pulse signal according to a high level output by the comparator; The input end of the counter is coupled to the output end of the pulse generator, and is suitable for performing statistics on the pulse signal, and judging whether a power outage occurs in the power grid according to the statistical result.

2. The grid voltage drop detection circuit according to claim 1, characterized in that: The grid voltage power failure detection circuit also includes a voltage divider circuit, wherein: The input end of the voltage divider circuit is coupled to the output end of the rectifier bridge circuit, and is suitable for reducing the amplitude of the steamed wave voltage, thereby obtaining the steamed wave voltage with a low amplitude; The voltage divider circuit includes two voltage divider resistors, and the middle point of the two voltage divider resistors is coupled to the signal processing circuit, so that the signal processing circuit can process the steamed bun wave voltage with low amplitude; One end of one of the voltage-dividing resistors is coupled to the output end of the rectifier bridge circuit, and the other end of the voltage-dividing resistor is connected to one end of another voltage-dividing resistor; the other end of the other voltage-dividing resistor is grounded.

3. The grid voltage drop detection circuit according to claim 1, characterized in that: Each unit circuit of the signal processing circuit further includes an anti-reverse diode, wherein: The input end of the anti-reverse diode is coupled to the output end of the pulse generator, and the output end of the anti-reverse diode is coupled to the input end of the counter.

4. The grid voltage drop detection circuit according to claim 1, characterized in that: A plurality of different reference voltages are preset, and the plurality of reference voltages correspond to a plurality of voltages within one cycle of the steamed-wave voltage, and the reference voltage connected to the second input terminal of each of the comparators is different.

5. The grid voltage drop detection circuit according to claim 1, characterized in that: The counter is suitable for counting pulse signals and judging whether a power outage occurs in the power grid according to the statistical results, wherein: The counter is used to count the number of pulse signals to determine whether a power outage occurs in the power grid; within a complete steamed-wave voltage cycle, when the steamed-wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of the reference voltage, it is determined that a power outage occurs in the power grid; Alternatively, the counter is used to count the time intervals of pulse signal transmissions, and when the time intervals do not meet preset requirements, it is determined that a power outage occurs in the power grid.

6. The grid voltage drop detection circuit according to claim 5, characterized in that: The counter is suitable for counting pulse signals and judging whether a power outage occurs in the power grid according to the statistical results, wherein: The counter is set with a target pulse number, and the counter is used to determine whether a power outage occurs in the power grid based on the target pulse number and the counted number of pulse signals. When the number of pulse signals counted by the counter is less than the target pulse number, it is determined that a power outage occurs in the power grid.

7. The grid voltage drop detection circuit according to any one of claims 1 to 6, characterized in that: The pulse generator is adapted to generate a pulse signal according to the high level output by the comparator, wherein: When the comparator transmits a high level to the pulse generator, the pulse generator detects the rising edge of the high level and immediately starts to generate a pulse signal, so as to ensure that each of the pulse generators generates only one pulse signal within a period of the steamed wave voltage; The pulse signal generated by the pulse generator is a narrow pulse, and the starting point of the narrow pulse is located in the first half cycle of the steamed bun wave voltage.

8. A method for detecting power failure of a power grid, characterized in that: The grid voltage power failure detection method is applied to the grid voltage power failure detection circuit according to any one of claims 1 to 7, comprising: The rectifier bridge circuit rectifies the alternating current and outputs a steamed wave voltage; The comparator compares the current voltage of the steamed-wave voltage with the reference voltage connected to the comparator, and then determines to output a high level or a low level according to the comparison result; The pulse generator generates a pulse signal according to the high level output by the comparator; The counter counts the pulse signal and determines whether a power outage occurs in the power grid according to the statistical result.

9. The method for detecting power failure of a power grid according to claim 8, characterized in that: The counter performs statistics on the pulse signal, and judging whether the power grid has a power failure according to the statistical result includes: The counter counts the number of pulse signals to determine whether a power outage occurs in the power grid; In a complete steamed-wave voltage cycle, when the steamed-wave voltage cycle is halfway through, when the number of pulse signals counted by the counter is less than the number of the reference voltage, it is determined that a power outage occurs in the power grid; Alternatively, the counter is set with a target pulse number, and when the number of pulse signals counted by the counter is less than the target pulse number, it is determined that a power outage occurs in the power grid.

10. The method for detecting power grid voltage drop according to claim 9, characterized in that: The counter performs statistics on the pulse signal, and judging whether the power grid has a power failure according to the statistical result includes: The counter counts the time intervals between pulse signal transmissions, and when the next pulse signal is not received within a preset time interval, it is determined that a power outage has occurred in the power grid.

Images