Method for fault detection of AC input voltage, detection device and power supply system

Abstract

The present disclosure relates to a method for fault detection of an alternating current (AC) input voltage, the method comprising: comparing the AC input voltage with a first reference voltage; comparing the AC input voltage with a second reference voltage less than the first reference voltage; and determining whether the AC input voltage has failed based on a result of the comparison, including: determining the AC input voltage to be normal if an absolute value of the AC input voltage is greater than a first reference voltage; if the absolute value of the AC input voltage remains within a range less than the second reference voltage for longer than a threshold time, the AC input voltage is determined to be malfunctioning; and if an absolute value of the AC input voltage is greater than or equal to the second reference voltage and less than or equal to the first reference voltage, and an absolute value of a rate of change of the AC input voltage remains within a range less than a voltage rate of change threshold for longer than a predetermined time delay, determining that the AC input voltage is malfunctioning.

Description

Technical Field

[0001] The present disclosure relates to a power supply fault detection technology, and more particularly, to a method, a detection device and a power supply system for detecting a fault of an alternating current (AC) input voltage. Background Art

[0002] Power converters usually use a sinusoidal AC input source as input power, and input voltage fault detection is critical to alert users of system power outages and take necessary actions. For power systems with automatic transfer switch (ATS) inputs, two AC sources are connected to one power converter. When the main input source fails, the ATS quickly switches the power converter input to another source before the power converter shuts down. These functions need to be implemented with fast AC voltage fault detection.

[0003] The present disclosure provides a fast AC voltage fault detection method by comparing the input voltage with an absolute threshold and comparing the voltage change rate with a minimum change rate threshold. Summary of the invention

[0004] The purpose of the embodiments of the present disclosure is to provide an effective solution for fault detection of an AC input voltage. Specifically, the embodiments of the present disclosure provide a method, a detection device and a power supply system for fault detection of an AC input voltage.

[0005] According to a first aspect of the present disclosure, a method for detecting faults of an alternating current (AC) input voltage is proposed, the method comprising: comparing the AC input voltage with a first reference voltage; comparing the AC input voltage with a second reference voltage that is smaller than the first reference voltage; and determining whether the AC input voltage is faulty based on a result of the comparison, comprising: if the absolute value of the AC input voltage is greater than the first reference voltage, the AC input voltage is determined to be normal; if the absolute value of the AC input voltage remains within a range less than the second reference voltage for a time longer than a threshold, the AC input voltage is determined to be faulty; and if the absolute value of the AC input voltage is greater than or equal to the second reference voltage and less than or equal to the first reference voltage, and the absolute value of the rate of change of the AC input voltage remains within a range less than a voltage change rate threshold for a time delay longer than a predetermined time, the AC input voltage is determined to be faulty.

[0006] In some embodiments, the threshold time is set to the sum of a time during which an absolute value of the AC input voltage is kept within a range less than the second reference voltage under normal circumstances and a time margin.

[0007] In some embodiments, the time margin is determined based on a maximum allowed time delay for reporting that the AC input voltage has failed.

[0008] In some embodiments, the voltage change rate threshold is set to the lowest voltage change rate of the AC input voltage under normal conditions minus an input voltage change rate margin.

[0009] In some embodiments, the input voltage change rate margin is determined according to a difference between a waveform of the AC input voltage under normal conditions and a pure sinusoidal waveform.

[0010] In some embodiments, the lowest voltage change rate is a voltage change rate at which the AC input voltage is the first reference voltage when the AC input voltage rises from the second reference voltage to the first reference voltage under normal circumstances.

[0011] In some embodiments, the waveform of the AC input voltage is a sine wave.

[0012] According to the second aspect of the present disclosure, there is also provided a detection device for performing fault detection on an AC input voltage, comprising: one or more processors; and one or more memories, wherein the one or more memories store computer executable instructions, and when the computer executable instructions are executed by the one or more processors, the one or more processors execute any of the above methods.

[0013] According to a third aspect of the present disclosure, a power supply system is also provided, comprising: a first AC input power supply; a second AC input power supply; a power converter connected to the first AC input power supply and the second AC input power supply; and a detection device according to the second aspect of the present disclosure, wherein when the detection device detects that the first AC input power supply fails, the power converter switches the input power to the second AC input power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present disclosure, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 1 is a waveform diagram showing a sinusoidal AC input voltage under normal conditions;

[0016] Figure 2 is a schematic flow chart showing a method for detecting a fault of an AC input voltage according to an embodiment of the present disclosure;

[0017] Figure 3 is a flowchart showing a specific implementation of a method for detecting a fault of an AC input voltage according to an embodiment of the present disclosure;

[0018] Figure 4 is a schematic block diagram showing a device for detecting a fault of an alternating current (AC) input voltage according to an embodiment of the present disclosure;

[0019] Figure 5 The embodiment according to the present disclosure includes Figure 4 Schematic block diagram of the power supply system of the device shown. DETAILED DESCRIPTION

[0020] Other aspects, advantages and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the disclosure taken in conjunction with the accompanying drawings.

[0021] In this disclosure, the terms "include" and "including" and their derivatives mean inclusion without limitation; the term "or" is inclusive, meaning and / or.

[0022] In this specification, the various embodiments described below for describing the principles of the present disclosure are merely illustrative and should not be interpreted in any way as limiting the scope of the disclosure. The following description with reference to the accompanying drawings is used to help fully understand the exemplary embodiments of the present disclosure as defined by the claims and their equivalents. The following description includes a variety of specific details to aid understanding, but these details should be considered merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, for the sake of clarity and brevity, descriptions of well-known functions and structures are omitted. In addition, throughout the accompanying drawings, the same figure numerals are used for similar functions and operations.

[0023] Figure 1 is a diagram showing a waveform of a sinusoidal AC input voltage under normal conditions.

[0024] like Figure 1 As shown, taking a sine wave as an example, the voltage value of the AC input voltage under normal conditions can be given by the following equation:

[0025] V in =V pk sin(2πFt)

[0026] Among them, V in Indicates the sinusoidal AC input voltage value, V pk represents the sinusoidal alternating current (AC) input peak voltage, F represents the sinusoidal alternating current (AC) input frequency, and t represents time.

[0027] Figure 2 is a schematic flow chart showing a method 200 for detecting a fault of an alternating current (AC) input voltage according to an embodiment of the present disclosure.

[0028] like Figure 2 As shown, the method 200 for detecting a fault of an AC input voltage according to an embodiment of the present disclosure may include:

[0029] Step S201: AC input voltage V in With the first reference voltage V th1 Make comparisons;

[0030] Step S202: The AC input voltage V in and the second reference voltage V th2 Make comparisons; and

[0031] Step S203: Determine the AC input voltage V according to the comparison result. in Whether a fault occurs.

[0032] Among them, the first reference voltage V th1 The second reference voltage V th2 It is the voltage level at which it is assumed that the power supply cannot draw enough power from the input and its output power is maintained only by the internal storage capacitors. Figure 3 is a flow chart showing a specific implementation of a method for detecting faults of an alternating current (AC) input voltage according to an embodiment of the present disclosure.

[0033] When the AC input voltage V in The absolute value of the first reference voltage V th1 When, that is, V in >V th1 or V in <-V th1 , it can be considered that the AC input voltage is sufficient to maintain continuous power supply operation, so the AC input voltage V in Determined as normal.

[0034] When the AC input voltage V in The absolute value of the second reference voltage V th2 When, that is, -V th2 <V in <V th2 , because the power supply cannot obtain enough power from the input, its output power is only maintained by the internal storage capacitor, and the power supply cannot work for a long time. Therefore, if the AC input voltage V in In-V th2 <V in <V th2 The stay time in the range exceeds the threshold time T acfail_th2 , then the AC input voltage V in is determined to be a fault. Among them, the threshold time Tacfail_th2 Determined according to the method described below.

[0035] AC input voltage V in From 0V to V th2 The time is T th2 (See Figure 1 ), then T th2 This can be derived from the following equation:

[0036]

[0037] Therefore, the AC input voltage V in Under normal circumstances, keep at -V th2 <Vin<V th2 The times in the range are:

[0038]

[0039] In order to pass V th2 To detect AC input voltage failure, the power supply can be considered to be able to operate at the minimum input RMS voltage, the peak voltage of which is V pk_min Assume that the AC input voltage has a minimum AC frequency F under normal conditions. min , and T within_th2 At the minimum AC frequency F min The longest one.

[0040] In order to have a certain design margin and avoid erroneously triggering the judgment of AC input voltage fault, T within_th2 Add the time margin ΔT to get T acfail_th2 The absolute value of the measured AC input voltage is less than V th2 If the time is longer than T acfail_th2 , it is considered that the AC input voltage fails. Among them, T acfail_th2 This can be derived from the following equation:

[0041]

[0042] The time margin ΔT may be determined based on the maximum allowable time delay for reporting an AC input voltage fault when the AC input voltage drops to 0 V. If it is required to report an AC input voltage fault before the power supply is powered off, the time margin ΔT may be determined based on the time the power supply output is maintained after the AC input voltage drops to 0 V (i.e., the time the internal storage capacitor maintains the power supply output power).

[0043] When the AC input voltage V inThe absolute value of the second reference voltage V th2 and is less than or equal to the first reference voltage V th1 When, that is, V th2 ≤V in ≤V th1 or -V th1 ≤V in ≤-V th2 For a sinusoidal AC input voltage, the voltage change rate under normal conditions is relatively high, which can be obtained from the following equation:

[0044]

[0045] If the input voltage rises or falls too slowly, the AC input voltage V in It will be determined as a fault. The rate of change of the input voltage is lowest at the minimum input RMS voltage and the minimum AC frequency. When the AC input voltage V in From V th2 Rising to V th1 The lowest voltage change rate will occur when the voltage is V th1 The minimum voltage change rate can be obtained from the following equation:

[0046] VCR min_th1_2 =2πF min ×V pk_min cos(2πF min T th1 )

[0047] in,

[0048]

[0049] When the AC input voltage V in From -V th2 Down to -V th1 When the voltage change rate is negative, the highest voltage change rate will occur when the voltage is -V th1 The maximum voltage change rate can be obtained from the following equation:

[0050] -VCR min_th1_2 =-(2πF min ×V pk_min cos(2πF min T th1 ))

[0051] Therefore, when the AC input voltage V in In V th2 ≤V in ≤V th1 or -V th1≤V in ≤-V th2 The input voltage change rate should not remain within the range of + / -VCR min_th1_2 Otherwise, the AC input voltage V in will be identified as a failure.

[0052] In order to have a certain design margin and avoid erroneously triggering the judgment of AC input voltage fault, the voltage change rate threshold VCR can be determined. acfail_th1_2 Subtract the voltage change rate margin ΔVCR from the voltage change rate threshold VCR. acfail_th1_2 This can be derived from the following equation:

[0053] VCR acfail_th1_2 =VCR min_th1_2 -ΔVCR

[0054] It should be noted that the AC input voltage V in The waveform is not necessarily a sine wave, it can also be other waveforms (such as square waves, etc.), and the above description only takes the sine wave as an example. Therefore, here, the voltage change rate margin ΔVCR is based on the AC input voltage V in The difference between the waveform under normal conditions and a pure sine waveform (crest factor = 1.414) is determined. In some cases, the power supply is required to operate within the range of input voltage crest factor of 1.1 to 1.6. Inputs with different voltage waveforms can be used to check the power supply operation, and a higher voltage change rate margin ΔVCR may be required.

[0055] When the AC input voltage V in In order to avoid falsely triggering the judgment of AC input voltage fault when there are some short spikes, sags or noises that do not affect the operation of the power converter, there should be a predefined time delay T acfail_th1_2 To determine the AC input voltage V in Is there a fault? As with the ΔT mentioned above, T acfail_th1_2 It should be defined based on the maximum time delay allowed for reporting an AC input voltage fault and the power supply output hold-up time.

[0056] For negative AC voltage cycles, the voltage rate of change considerations are the same, only the input voltage is reversed.

[0057] Therefore, when V th2 ≤V in ≤V th1 or -V th1 ≤V in ≤-V th2 If the AC input voltage V inThe absolute value of the voltage change rate is kept below the voltage change rate threshold VCR acfail_th1_2 within the range, that is,

[0058]

[0059] Reaching a delay longer than the preset time T acfail_th1_2 , then the AC input voltage V in Determined to be faulty.

[0060] Figure 4 4 is a schematic block diagram showing a device 400 for detecting faults of an alternating current (AC) input voltage according to an embodiment of the present disclosure. Figure 4 The device shown can be any device with processing capability. Figure 4 The device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0061] like Figure 4 As shown, the device 400 according to this embodiment includes one or more processors 401_1, 401_2, ..., 401_n and one or more memories 402_1, 402_2, ..., 402_n. The process or method described above with reference to the flowchart can be implemented as a computer executable instruction. The processor can execute the above method defined in the embodiment of the present application according to the computer executable instructions stored in the memory.

[0062] Computer executable instructions for implementing the various embodiments of the present disclosure may be stored on a computer storage medium. The corresponding functions may be implemented by enabling a computer system to read the computer executable instructions on the computer storage medium and execute these instructions. The so-called "computer system" herein may be a computer system embedded in the device, which may include an operating system or hardware (such as a peripheral device). The computer storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared or semiconductor system, device or device, or any combination of the above. More specific examples of computer storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present disclosure, a computer storage medium may be any tangible medium that contains or stores computer executable instructions. The instructions contained on the computer storage medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable or RF, etc., or any suitable combination of the above.

[0063] The various features or functional modules of the devices used in the above embodiments can be implemented or executed by circuits (e.g., monolithic or multi-chip integrated circuits). Circuits designed to perform the functions described in this specification may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above devices. The general-purpose processor may be a microprocessor, or any existing processor, controller, microcontroller, or state machine. The above circuits may be digital circuits or analog circuits. In the case where new integrated circuit technologies have emerged to replace existing integrated circuits due to advances in semiconductor technology, one or more embodiments of the present disclosure may also be implemented using these new integrated circuit technologies.

[0064] Figure 5 The embodiment according to the present disclosure includes Figure 4 A schematic block diagram of a power supply system 500 of the device is shown. Figure 5 The system shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0065] like Figure 5 As shown, the power supply system 500 according to this embodiment includes a first AC input power supply 501, a second AC input power supply 502, a power converter 503, and Figure 4 The device 504 shown in FIG. 5 is a device 504. The power converter 503 is respectively connected to the first AC input power source 501, the second AC input power source 502 and the device 504. When the device 504 detects that the first AC input power source 504 fails, the power converter 503 switches the input power source to the second AC input power source 502. This function needs to be implemented by the above-mentioned method for detecting the fault of the AC input voltage.

[0066] As described above, the method of the present disclosure and the devices and systems involved have been described in detail with reference to the accompanying drawings. However, it should be understood by those skilled in the art that the embodiments of the present disclosure are exemplary only and not restrictive. The methods shown herein are not limited to the steps and sequences shown. The devices shown herein may include more modules, for example, modules that can be developed or developed in the future and can be used for the device, etc. In addition, those skilled in the art may make various improvements, modifications and substitutions to the present disclosure within the scope of the claims.

Claims

1. A method for detecting a fault in an AC input voltage, the method comprising: comparing the AC input voltage to a first reference voltage; comparing the AC input voltage to a second reference voltage that is less than the first reference voltage; as well as Based on the comparison result, determining whether the AC input voltage fails comprises: If the absolute value of the AC input voltage is greater than the first reference voltage, the AC input voltage is determined to be normal; If the absolute value of the AC input voltage remains within a range less than the second reference voltage for longer than a threshold time, the AC input voltage is determined to be faulty; and If the absolute value of the AC input voltage is greater than or equal to the second reference voltage and less than or equal to the first reference voltage, and the absolute value of the rate of change of the AC input voltage remains within a range less than a voltage change rate threshold for longer than a predetermined time delay, the AC input voltage is determined to be faulty.

2. The method according to claim 1, wherein: The threshold time is set to the sum of a time during which the absolute value of the AC input voltage is kept within a range smaller than the second reference voltage under normal circumstances and a time margin.

3. The method according to claim 2, wherein: The time margin is determined based on a maximum allowed time delay for reporting a fault in the AC input voltage.

4. The method according to claim 1, wherein: The voltage change rate threshold is set to the lowest voltage change rate of the AC input voltage under normal conditions minus an input voltage change rate margin.

5. The method according to claim 4, wherein: The input voltage change rate margin is determined according to the difference between a waveform of the AC input voltage under normal conditions and a pure sinusoidal waveform.

6. The method according to claim 5, wherein: The lowest voltage change rate is a voltage change rate at which the AC input voltage is the first reference voltage when the AC input voltage rises from the second reference voltage to the first reference voltage under normal circumstances.

7. The method according to any one of claims 1 to 6, wherein: The waveform of the AC input voltage is a sine wave.

8. A device for detecting faults in an AC input voltage, comprising: one or more processors; as well as One or more memories storing computer executable instructions which, when executed by the one or more processors, cause the one or more processors to perform the method according to any one of claims 1 to 7.

9. A computer storage medium having computer executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the method according to any one of claims 1 to 7.

10. A power supply system, comprising: A first AC input power source; Second AC input power supply; A power converter connected to the first AC input power source and the second AC input power source; as well as According to the device of claim 8, when the device detects that the first AC input power fails, the power converter switches the input power to the second AC input power.

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