Three-phase electrical detection method and circuit

Abstract

The present application discloses a three-phase electrical detection method and circuit, the method comprising: obtaining a pulsating DC signal, the pulsating DC signal being obtained by rectifying an input electrical signal; comparing the pulsating DC signal with a preset first threshold voltage to obtain a first comparison signal; comparing the pulsating DC signal with a preset second threshold voltage to obtain a second comparison signal; determining whether the input electrical signal is over-voltage and phase-missing according to the first comparison signal; and determining whether the input electrical signal is under-voltage and phase-missing according to the second comparison signal.

Description

Technical Field

[0001] The present application relates to the technical field of power supply equipment, and in particular to a three-phase power detection method and circuit. Background Art

[0002] In a switching power supply, in order to protect the switching power supply from damage caused by fluctuations in the external power grid, it is often necessary to set an over-voltage and under-voltage detection protection circuit at the input end. The over-voltage and under-voltage detection protection circuit rectifies the three-phase AC power and converts it into a pulsating DC signal. After filtering by a capacitor, a relatively smooth DC signal is obtained as a detection signal, and the over-voltage and under-voltage are determined based on the DC signal. When a phase loss occurs in a live wire of the three-phase AC power, the voltage peak of the three-phase AC power remains unchanged, while the voltage of the filtered DC signal decreases. Since the over-voltage and under-voltage detection protection circuit detects the DC signal, it is determined to be an undervoltage state and the undervoltage protection is triggered, and the switching power supply stops working.

[0003] However, in some specific occasions, the switching power supply still needs to maintain a certain load-carrying capacity when the three-phase AC power is in a phase-loss state, and the existing over-voltage and under-voltage detection protection circuit cannot meet the requirements of the switching power supply in the phase-loss state. Summary of the invention

[0004] The present application aims to propose a three-phase power detection method and circuit that can meet the needs of a switching power supply operating in the event of a phase loss.

[0005] In a first aspect, an embodiment of the present application provides a three-phase electrical detection method, comprising:

[0006] Acquiring a pulsating DC signal, wherein the pulsating DC signal is obtained by rectifying an input electrical signal;

[0007] Comparing the pulsating DC signal with a preset first threshold voltage to obtain a first comparison signal;

[0008] Comparing the pulsating DC signal with a preset second threshold voltage to obtain a second comparison signal;

[0009] Determine whether the input electrical signal is over-voltage or phase-lost according to the first comparison signal;

[0010] Whether the input electrical signal is under-voltage and phase-lost is determined according to the second comparison signal.

[0011] According to some embodiments of the present application, the first threshold voltage is obtained by the following formula:

[0012]

[0013] Among them, V H is the first threshold voltage, V rms-H is the overvoltage protection point voltage, and k is the attenuation coefficient.

[0014] According to some embodiments of the present application, the second threshold voltage is obtained by the following formula:

[0015]

[0016] Among them, V L is the second threshold voltage, V rms-L is the undervoltage protection point voltage, and k is the attenuation coefficient.

[0017] According to some embodiments of the present application, determining whether the input electrical signal is over-voltage and phase-lost according to the first comparison signal includes:

[0018] If the first comparison signal is always at a low level, it is confirmed that the input electrical signal is over-voltage and has no phase loss;

[0019] If the first comparison signal is always at a high level, it is confirmed that the input electrical signal is not over-voltage;

[0020] If the frequency of the first comparison signal is the first preset frequency, it is confirmed that the input electrical signal is phase-deficient and over-voltage;

[0021] If the frequency of the first comparison signal is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not over-voltage.

[0022] According to some embodiments of the present application, determining whether the input electrical signal is undervoltage and phase-lost according to the second comparison signal includes:

[0023] If the second comparison signal is always at a high level, it is confirmed that the input electrical signal is not under-voltage and has no phase loss;

[0024] If the second comparison signal is always at a low level, it is confirmed that the input electrical signal is under-voltage;

[0025] If the frequency of the second comparison signal is the first preset frequency, it is confirmed that the input electrical signal is missing a phase and is not undervoltage;

[0026] If the frequency of the second comparison signal is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not under-voltage.

[0027] In a second aspect, an embodiment of the present application provides a three-phase power detection circuit, including:

[0028] A rectifier unit, the rectifier unit is used to rectify the input electrical signal to obtain a pulsating DC signal;

[0029] a first comparison unit, the first comparison unit being connected to the rectification unit, and being used for comparing the pulsating DC signal with a preset first threshold voltage, and outputting a first comparison signal;

[0030] a second comparing unit, the second comparing unit being connected to the rectifying unit, and being used for comparing the pulsating DC signal with a preset second threshold voltage, and outputting a second comparison signal;

[0031] The first comparison signal and the second comparison signal are used to determine whether the input electrical signal is undervoltage and phase-lost.

[0032] According to some embodiments of the present application, the first comparing unit includes:

[0033] A first comparator, wherein the non-inverting input terminal of the first comparator is used to input the first threshold voltage, the inverting input terminal of the first comparator is connected to the rectifier unit, and the output terminal of the first comparator outputs the first comparison signal.

[0034] According to some embodiments of the present application, the second comparing unit includes:

[0035] A second comparator, wherein the non-inverting input terminal of the second comparator is connected to the rectifier unit, the inverting input terminal of the second comparator is used to input the second threshold voltage, and the output terminal of the second comparator outputs the second comparison signal.

[0036] According to some embodiments of the present application, the rectifying unit includes:

[0037] A first end, a second end and a third end for inputting the input electrical signal;

[0038] a first diode, wherein an anode of the first diode is connected to the first end, and a cathode of the first diode is connected to the first comparing unit and the second comparing unit respectively;

[0039] a second diode, wherein an anode of the second diode is connected to the second end, and a cathode of the second diode is connected to the first comparing unit and the second comparing unit respectively;

[0040] a third diode, wherein an anode of the third diode is connected to the third end, and a cathode of the third diode is connected to the first comparing unit and the second comparing unit respectively;

[0041] a fourth diode, wherein a cathode of the fourth diode is connected to the first end, and an anode of the fourth diode is connected to the first comparing unit and the second comparing unit respectively;

[0042] a fifth diode, wherein a cathode of the fifth diode is connected to the second end, and an anode of the fifth diode is connected to the first comparing unit and the second comparing unit respectively;

[0043] A sixth diode, wherein a cathode of the sixth diode is connected to the third end, and an anode of the sixth diode is respectively connected to the first comparing unit and the second comparing unit.

[0044] According to some embodiments of the present application, it further includes:

[0045] a first resistor, wherein a first end of the first resistor is respectively connected to a cathode of the first diode, a cathode of the second diode, and a cathode of the third diode, and a second end of the first resistor is respectively connected to the first comparing unit and the second comparing unit;

[0046] A second resistor, wherein a first end of the second resistor is connected to a second end of the first resistor, and a second end of the second resistor is respectively connected to an anode of the fourth diode, an anode of the fifth diode, and an anode of the sixth diode.

[0047] In an embodiment of the present application, over-voltage, under-voltage and phase loss detection is performed on the pulsating DC signal obtained after rectifying the input electrical signal. Since the magnitude of the pulsating DC signal is the peak voltage of the input electrical signal, the peak voltage of the input electrical signal is the same in both phase loss and non-phase loss conditions. Therefore, the under-voltage judgment will not be affected by the phase loss, so as to maintain the load capacity of the switching power supply in the case of phase loss.

[0048] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0050] Figure 1 A flowchart of an embodiment of a three-phase electrical detection method provided by the present application;

[0051] Figure 2 A circuit diagram of an embodiment of a three-phase electrical detection circuit provided by the present application. DETAILED DESCRIPTION

[0052] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0053] In the description of the present application, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0054] In the description of this application, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0055] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0056] Refer to the following Figure 1 to Figure 2 A three-phase electrical detection method and circuit according to an embodiment of the present application are described.

[0057] An embodiment of the present application provides a three-phase electrical detection method, such as Figure 1 As shown, including:

[0058] Step S100, obtaining a pulsating DC signal, where the pulsating DC signal is obtained by rectifying an input electrical signal;

[0059] Step S200, comparing the pulsating DC signal with a preset first threshold voltage VH to obtain a first comparison signal VH1;

[0060] Step S300, comparing the pulsating DC signal with a preset second threshold voltage VL to obtain a second comparison signal VL1;

[0061] Step S400, determining whether the input electrical signal is over-voltage and phase-lost according to the first comparison signal VH1;

[0062] Step S500: Determine whether the input electrical signal is undervoltage and phase-lost according to the second comparison signal VL1.

[0063] In an embodiment of the present application, over-voltage, under-voltage and phase loss detection is performed on the pulsating DC signal obtained after rectifying the input electrical signal. Since the magnitude of the pulsating DC signal is the peak voltage of the input electrical signal, the peak voltage of the input electrical signal is the same in both phase loss and non-phase loss conditions. Therefore, the under-voltage judgment will not be affected by the phase loss, so as to maintain the load capacity of the switching power supply in the case of phase loss.

[0064] When judging overvoltage and undervoltage, the pulsating DC signal is compared with the first threshold voltage VH and the second threshold voltage VL to determine whether it is undervoltage or overvoltage.

[0065] Since the three-phase electrical signal is a DC signal after rectification and filtering, the corresponding voltage effective values ​​are different in the two cases of phase loss and phase non-loss. Therefore, to determine whether there is undervoltage, it is necessary to set two different threshold voltages for the two cases of phase loss and phase non-loss for judgment. Similarly, to determine whether there is overvoltage, it is also necessary to set two different threshold voltages for the two cases of phase loss and phase non-loss for judgment. In this embodiment, since the size of the pulsating DC signal is the peak voltage of the input electrical signal, the peak voltage of the input electrical signal is the same in both the cases of phase loss and phase non-loss. Therefore, it is only necessary to determine whether there is overvoltage based on the first threshold voltage VH, and to determine whether there is undervoltage based on the second threshold voltage VL.

[0066] In order to better illustrate a three-phase electrical detection method and circuit according to an embodiment of the present application, the input electrical signal is analyzed below.

[0067] The three-phase voltage is:

[0068]

[0069]

[0070]

[0071] Three-phase line voltage:

[0072]

[0073]

[0074]

[0075] Where f0 is the phase voltage frequency, V rms is the effective value of the phase voltage.

[0076] When the three-phase voltages of the input electrical signal are normal, the pulsating DC signal obtained after rectification will be a "steamed bun wave", and its peak voltage is the peak voltage of the two-phase line voltage, so:

[0077]

[0078] Among them, V 0max is the peak voltage of the pulsating DC signal.

[0079] The minimum value of the pulsating DC signal is obtained when the two-phase voltages are equal, that is:

[0080] V a =V b ,

[0081]

[0082]

[0083] It can be obtained that the minimum value of the pulsating DC signal is:

[0084]

[0085] Among them, V 0min is the minimum value of the pulsating DC signal.

[0086] The pulsating DC signal will experience V in one cycle. a >V b 、V a <V b 、V b >V c 、V b <V c 、V a >V c 、V a <V c There are six situations, so the frequency of the pulsating DC signal will be 6 times that of the input electrical signal, and the frequency of the pulsating DC signal is 6f0.

[0087] From the above, we can see that when the input electrical signal is normal, the voltage range of the pulsating DC signal after rectification is The frequency is 6f0.

[0088] When one phase of the input electrical signal is missing, the peak voltage of the pulsating DC signal after rectification is the peak voltage of the two-phase line voltage, that is:

[0089]

[0090] The minimum value of the pulsating DC signal is obtained when the two-phase voltages are equal, that is:

[0091] V 0min =0,

[0092] The pulsating DC signal will experience V in the absence of phase c within one cycle. a >V b 、V a <V b In the case of lack of other phases, the same two situations will be experienced, so the frequency will be twice that of three-phase electricity, and the frequency will be 2f0

[0093] Therefore, when one phase of the input electrical signal is missing, the voltage range of the rectified pulsating DC signal is The frequency is 2f0.

[0094] In some embodiments of the present application, the first threshold voltage VH is obtained by the following formula:

[0095]

[0096] Among them, V H is the first threshold voltage VH, V rms-H is the overvoltage protection point voltage, and k is the attenuation coefficient.

[0097] In this embodiment, the maximum value of the pulsating DC signal is proportional to the effective value of the phase voltage, that is, Therefore, the input electrical signal can be judged as undervoltage or overvoltage based on the maximum value of the pulsating DC signal. In other words, the maximum value of the pulsating DC signal is divided by Then compare it with the overvoltage protection point voltage, or multiply the overvoltage protection point voltage by By comparing it with the maximum value of the pulsating DC signal, it can be determined whether the input electrical signal is overvoltage.

[0098] Generally, the pulsating DC signal will be attenuated by the resistor before being compared with the first threshold voltage VH. Therefore, the first threshold voltage VH should also be reduced in proportion to the attenuation coefficient k. Therefore, the first threshold voltage VH is Furthermore, whether the input electrical signal is over-voltage can be determined according to the first threshold voltage VH and the pulsating DC signal.

[0099] In this implementation, the overvoltage protection point voltage is a threshold voltage for determining whether an input electrical signal is overvoltage, and the overvoltage protection point voltage can be set according to actual application scenarios.

[0100] In some embodiments of the present application, the second threshold voltage VL is obtained by the following formula:

[0101]

[0102] Among them, V L is the second threshold voltage VL, V rms-L is the undervoltage protection point voltage, and k is the attenuation coefficient.

[0103] In this embodiment, the maximum value of the pulsating DC signal is proportional to the effective value of the phase voltage, that is, Therefore, the input electrical signal can be judged as undervoltage or overvoltage according to the maximum value of the pulsating DC signal. In other words, the maximum value of the pulsating DC signal is divided by Then compare it with the undervoltage protection point voltage, or multiply the undervoltage protection point voltage by By comparing it with the maximum value of the pulsating DC signal, it can be determined whether the input electrical signal is undervoltage.

[0104] Generally, the pulsating DC signal will be attenuated by the resistor before being compared with the second threshold voltage VL. Therefore, the second threshold voltage VL should also be reduced in proportion to the attenuation coefficient k. Therefore, the second threshold voltage VL is Furthermore, whether the input electrical signal is under-voltage can be determined according to the second threshold voltage VL and the pulsating DC signal.

[0105] In this implementation, the undervoltage protection point voltage is a threshold voltage for determining whether the input electrical signal is undervoltage, and the undervoltage protection point voltage can be set according to actual application scenarios.

[0106] In some embodiments of the present application, the step S400 of “determining whether the input electrical signal is over-voltage and phase-lost according to the first comparison signal VH1” is further described, and the step S400 includes:

[0107] Step S410: If the first comparison signal VH1 is always at a low level, it is confirmed that the input electrical signal is over-voltage and has no phase loss;

[0108] Step S420: If the first comparison signal VH1 is always at a high level, it is confirmed that the input electrical signal is not over-voltage;

[0109] Step S430: If the frequency of the first comparison signal VH1 is the first preset frequency, it is confirmed that the input electrical signal is phase-lost and over-voltage;

[0110] Step S440 : If the frequency of the first comparison signal VH1 is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not over-voltage.

[0111] In this embodiment, the first comparison signal VH1 is always at a low level, indicating that the voltage of the pulsating DC signal is greater than the first threshold voltage VH, confirming that the input electrical signal is over-voltage and not missing phase. If the first comparison signal VH1 is always at a high level, indicating that the voltage of the pulsating DC signal is less than the first threshold voltage VH, confirming that the input electrical signal is not over-voltage.

[0112] When the first comparison signal VH1 is neither constantly at a high level nor constantly at a low level, it indicates that the voltage of the pulsating DC signal is greater than the first threshold voltage VH, that is, the input electrical signal is overvoltage. If the frequency of the first comparison signal VH1 is the first preset frequency, it is confirmed that the input electrical signal is phase-deficient and overvoltage. If the frequency of the first comparison signal VH1 is the second preset frequency, it is confirmed that the input electrical signal is not phase-deficient and overvoltage.

[0113] In some embodiments of the present application, the first preset frequency is 6f0, the second preset frequency is 2f0, and f0 is the frequency of the input electrical signal.

[0114] In some embodiments of the present application, the step S500 of “determining whether the input electrical signal is undervoltage and phase-lost according to the second comparison signal VL1” is further described, and the step S500 includes:

[0115] Step S510: If the second comparison signal VL1 is always at a high level, it is confirmed that the input electrical signal is not under-voltage and has no phase loss;

[0116] Step S520: If the second comparison signal VL1 is always at a low level, it is confirmed that the input electrical signal is under-voltage;

[0117] Step S530: If the frequency of the second comparison signal VL1 is the first preset frequency, it is confirmed that the input electrical signal is phase-lost and not undervoltage;

[0118] Step S540 : If the frequency of the second comparison signal VL1 is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not under-voltage.

[0119] In this embodiment, the second comparison signal VL1 is always at a high level, indicating that the voltage of the pulsating DC signal is greater than the second threshold voltage VL, confirming that the input electrical signal is not under-voltage and has no phase loss. The second comparison signal VL1 is always at a low level, indicating that the voltage of the pulsating DC signal is less than the second threshold voltage VL, confirming that the input electrical signal is under-voltage.

[0120] When the second comparison signal VL1 is neither constantly at a high level nor constantly at a low level, if the frequency of the second comparison signal VL1 is the first preset frequency, it is confirmed that the input electrical signal is phase-deficient and not under-voltage; if the frequency of the second comparison signal VL1 is the second preset frequency, it is confirmed that the input electrical signal is not phase-deficient and not under-voltage.

[0121] In addition, the embodiment of the present application provides a three-phase power detection circuit, such as Figure 2 As shown, including:

[0122] A rectifier unit, which is used to rectify the input electrical signal to obtain a pulsating DC signal;

[0123] A first comparison unit, the first comparison unit is connected to the rectification unit, and the first comparison unit is used to compare the pulsating DC signal with a preset first threshold voltage VH, and output a first comparison signal VH1;

[0124] a second comparison unit, the second comparison unit is connected to the rectification unit, and is used for comparing the pulsating DC signal with a preset second threshold voltage VL, and outputting a second comparison signal VL1;

[0125] The first comparison signal VH1 and the second comparison signal VL1 are used to determine whether the input electrical signal is under-voltage and phase-lost.

[0126] In this embodiment, over-voltage, under-voltage and phase loss detection is performed on the pulsating DC signal obtained after rectifying the input electrical signal. Since the magnitude of the pulsating DC signal is the peak voltage of the input electrical signal, the peak voltage of the input electrical signal is the same in both phase loss and non-phase loss conditions. Therefore, the under-voltage judgment will not be affected by the phase loss, so as to maintain the load capacity of the switching power supply in the case of phase loss.

[0127] When judging overvoltage and undervoltage, the pulsating DC signal is compared with the first threshold voltage VH and the second threshold voltage VL to determine whether it is undervoltage or overvoltage.

[0128] Since the three-phase electrical signal is a DC signal after rectification and filtering, the corresponding voltage effective values ​​are different in the two cases of phase loss and phase non-loss. Therefore, to determine whether there is undervoltage, it is necessary to set two different threshold voltages for the two cases of phase loss and phase non-loss for judgment. Similarly, to determine whether there is overvoltage, it is also necessary to set two different threshold voltages for the two cases of phase loss and phase non-loss for judgment. In this embodiment, since the size of the pulsating DC signal is the peak voltage of the input electrical signal, the peak voltage of the input electrical signal is the same in both the cases of phase loss and phase non-loss. Therefore, it is only necessary to determine whether there is overvoltage based on the first threshold voltage VH, and to determine whether there is undervoltage based on the second threshold voltage VL.

[0129] In some embodiments of the present application, Figure 2 As shown, the first comparison unit includes:

[0130] The first comparator U1 has a non-inverting input terminal for inputting a first threshold voltage VH, an inverting input terminal of the first comparator U1 is connected to a rectifying unit, and an output terminal of the first comparator U1 outputs a first comparison signal VH1.

[0131] In this embodiment, the first comparator U1 compares the first threshold voltage VH with the pulsating DC signal to obtain a first comparison signal VH1.

[0132] In some embodiments of the present application, Figure 2 As shown, the second comparison unit includes:

[0133] The second comparator U2 has a non-inverting input terminal connected to the rectifier unit, an inverting input terminal of the second comparator U2 is used to input a second threshold voltage VL, and an output terminal of the second comparator U2 outputs a second comparison signal VL1.

[0134] In this embodiment, the second comparator U2 compares the second threshold voltage VL with the pulsating DC signal to obtain a second comparison signal VL1.

[0135] In some embodiments of the present application, Figure 2 As shown, the rectifier unit includes:

[0136] a first terminal, a second terminal and a third terminal for inputting an input electrical signal;

[0137] A first diode D1, wherein an anode of the first diode D1 is connected to the first end, and a cathode of the first diode D1 is connected to the first comparing unit and the second comparing unit respectively;

[0138] a second diode D2, wherein an anode of the second diode D2 is connected to the second end, and a cathode of the second diode D2 is connected to the first comparing unit and the second comparing unit respectively;

[0139] a third diode D3, wherein an anode of the third diode D3 is connected to the third end, and a cathode of the third diode D3 is connected to the first comparing unit and the second comparing unit respectively;

[0140] a fourth diode D4, wherein a cathode of the fourth diode D4 is connected to the first end, and an anode of the fourth diode D4 is connected to the first comparing unit and the second comparing unit respectively;

[0141] a fifth diode D5, wherein a cathode of the fifth diode D5 is connected to the second end, and an anode of the fifth diode D5 is connected to the first comparing unit and the second comparing unit respectively;

[0142] A sixth diode D6, wherein a cathode of the sixth diode D6 is connected to the third end, and an anode of the sixth diode D6 is connected to the first comparing unit and the second comparing unit respectively.

[0143] In this embodiment, the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, the fifth diode D5 and the sixth diode D6 form a rectifier bridge, and the input electrical signal is rectified by the rectifier bridge to obtain a pulsating DC signal.

[0144] According to some embodiments of the present application, Figure 2 As shown, it also includes:

[0145] a first resistor R1, wherein a first end of the first resistor R1 is respectively connected to a cathode of the first diode D1, a cathode of the second diode D2, and a cathode of the third diode D3, and a second end of the first resistor R1 is respectively connected to a first comparing unit and a second comparing unit;

[0146] The second resistor R2 has a first end connected to the second end of the first resistor R1 , and a second end connected to the anode of the fourth diode D4 , the anode of the fifth diode D5 , and the anode of the sixth diode D6 .

[0147] In this embodiment, the first resistor R1 and the second resistor R2 attenuate the pulsating DC signal, and input the attenuated pulsating DC signal into the first comparison unit and the second comparison unit.

[0148] The attenuation coefficient is calculated using the following formula:

[0149]

[0150] Where k is the attenuation coefficient, R i1 is the resistance value of the first resistor R1, R i2 is the resistance value of the second resistor R2.

[0151] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A three-phase electrical detection method, characterized in that: include: Acquiring a pulsating DC signal, wherein the pulsating DC signal is obtained by rectifying an input electrical signal; Comparing the pulsating DC signal with a preset first threshold voltage to obtain a first comparison signal; Comparing the pulsating DC signal with a preset second threshold voltage to obtain a second comparison signal; Determine whether the input electrical signal is over-voltage or phase-lost according to the first comparison signal; Whether the input electrical signal is under-voltage and phase-lost is determined according to the second comparison signal.

2. The three-phase electrical detection method according to claim 1, characterized in that: The first threshold voltage is obtained by the following formula: Among them, V H is the first threshold voltage, V rms-H is the overvoltage protection point voltage, and k is the attenuation coefficient.

3. The three-phase electrical detection method according to claim 1, characterized in that: The second threshold voltage is obtained by the following formula: Among them, V L is the second threshold voltage, V rms-L is the undervoltage protection point voltage, and k is the attenuation coefficient.

4. The three-phase electrical detection method according to claim 1, characterized in that: The determining, according to the first comparison signal, whether the input electrical signal is over-voltage or phase-lost comprises: If the first comparison signal is always at a low level, it is confirmed that the input electrical signal is over-voltage and has no phase loss; If the first comparison signal is always at a high level, it is confirmed that the input electrical signal is not over-voltage; If the frequency of the first comparison signal is the first preset frequency, it is confirmed that the input electrical signal is phase-deficient and over-voltage; If the frequency of the first comparison signal is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not over-voltage.

5. The three-phase electrical detection method according to claim 1, characterized in that: The determining whether the input electrical signal is undervoltage and phase-lost according to the second comparison signal comprises: If the second comparison signal is always at a high level, it is confirmed that the input electrical signal is not under-voltage and has no phase loss; If the second comparison signal is always at a low level, it is confirmed that the input electrical signal is under-voltage; If the frequency of the second comparison signal is the first preset frequency, it is confirmed that the input electrical signal is missing a phase and is not undervoltage; If the frequency of the second comparison signal is the second preset frequency, it is confirmed that the input electrical signal is not missing a phase and is not under-voltage.

6. A three-phase electrical detection circuit, characterized in that: include: A rectifier unit, the rectifier unit is used to rectify the input electrical signal to obtain a pulsating DC signal; a first comparison unit, the first comparison unit being connected to the rectification unit, and being used for comparing the pulsating DC signal with a preset first threshold voltage, and outputting a first comparison signal; a second comparing unit, the second comparing unit being connected to the rectifying unit, and being used for comparing the pulsating DC signal with a preset second threshold voltage, and outputting a second comparison signal; The first comparison signal and the second comparison signal are used to determine whether the input electrical signal is undervoltage and phase-lost.

7. The three-phase electrical detection circuit according to claim 6, characterized in that: The first comparison unit comprises: A first comparator, wherein the non-inverting input terminal of the first comparator is used to input the first threshold voltage, the inverting input terminal of the first comparator is connected to the rectifier unit, and the output terminal of the first comparator outputs the first comparison signal.

8. The three-phase electrical detection circuit according to claim 6, characterized in that: The second comparison unit comprises: A second comparator, wherein the non-inverting input terminal of the second comparator is connected to the rectifier unit, the inverting input terminal of the second comparator is used to input the second threshold voltage, and the output terminal of the second comparator outputs the second comparison signal.

9. The three-phase electrical detection circuit according to claim 6, characterized in that: The rectifying unit comprises: A first end, a second end and a third end for inputting the input electrical signal; a first diode, wherein an anode of the first diode is connected to the first end, and a cathode of the first diode is connected to the first comparing unit and the second comparing unit respectively; a second diode, wherein an anode of the second diode is connected to the second end, and a cathode of the second diode is connected to the first comparing unit and the second comparing unit respectively; a third diode, wherein an anode of the third diode is connected to the third end, and a cathode of the third diode is connected to the first comparing unit and the second comparing unit respectively; a fourth diode, wherein a cathode of the fourth diode is connected to the first end, and an anode of the fourth diode is connected to the first comparing unit and the second comparing unit respectively; a fifth diode, wherein a cathode of the fifth diode is connected to the second end, and an anode of the fifth diode is connected to the first comparing unit and the second comparing unit respectively; A sixth diode, wherein a cathode of the sixth diode is connected to the third end, and an anode of the sixth diode is connected to the first comparing unit and the second comparing unit respectively.

10. The three-phase electrical detection circuit according to claim 9, characterized in that: Also includes: a first resistor, wherein a first end of the first resistor is respectively connected to a cathode of the first diode, a cathode of the second diode, and a cathode of the third diode, and a second end of the first resistor is respectively connected to the first comparing unit and the second comparing unit; A second resistor, wherein a first end of the second resistor is connected to a second end of the first resistor, and a second end of the second resistor is respectively connected to an anode of the fourth diode, an anode of the fifth diode, and an anode of the sixth diode.

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