Three-phase alternating voltage detection method, device, equipment and power system

Abstract

The application relates to a three-phase alternating voltage detection method, device, equipment and power system. First, a first voltage signal, a second voltage signal and a third voltage signal are acquired, the first voltage signal is from a first optocoupler, the first optocoupler is connected to a first-phase alternating voltage through a first current limiting circuit; the second voltage signal is from a second optocoupler, the second optocoupler is connected to a second-phase alternating voltage through a second current limiting circuit; the third voltage signal is from a third optocoupler, the third optocoupler is connected to a third-phase alternating voltage through a third current limiting circuit; then, the time between the rising edge and the falling edge of a square wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain a voltage timing time; and then, the first-phase alternating voltage, the second-phase alternating voltage and the third-phase alternating voltage are detected according to the voltage timing time. The method can realize the detection of the three-phase alternating voltage through one single-chip microcomputer pin, saves the single-chip microcomputer pin resources and improves the detection efficiency.

Description

Technical Field

[0001] This application relates to the field of three-phase AC voltage detection technology, and in particular to a three-phase AC voltage detection method, device, equipment and power system. Background Technology

[0002] With the development of science and technology, various electrical devices have emerged, bringing great convenience to people's work and life. Three-phase alternating current (AC) is a power system composed of three AC circuits with the same frequency, equal potential amplitude, and a phase difference of 120°. Three-phase AC is widely used in various electrical devices and is an important guarantee for their normal operation. However, in actual use, if the three-phase AC is abnormal, it may damage the electrical equipment or even become a safety hazard. Therefore, it is very important to test the three-phase AC.

[0003] Traditional methods for detecting three-phase AC power use three external interrupt ports on a microcontroller for voltage input and detection. However, this method consumes too many pin resources of the microcontroller, resulting in resource waste and low detection efficiency. Summary of the Invention

[0004] Therefore, it is necessary to provide a three-phase AC voltage detection method, device, equipment, and power system that can save detection resources and improve detection efficiency in order to address the above-mentioned technical problems.

[0005] Firstly, this application provides a method for detecting three-phase AC voltage. The method includes:

[0006] Acquire a first voltage signal, a second voltage signal, and a third voltage signal; the first voltage signal comes from a first optocoupler, which is connected to a first phase AC voltage through a first current limiting circuit; the second voltage signal comes from a second optocoupler, which is connected to a second phase AC voltage through a second current limiting circuit; the third voltage signal comes from a third optocoupler, which is connected to a third phase AC voltage through a third current limiting circuit.

[0007] The voltage timing time is obtained by timing the time between the rising edge and the falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal;

[0008] The first phase AC voltage, the second phase AC voltage, and the third phase AC voltage are detected based on the voltage timing time.

[0009] In one embodiment, the voltage timing includes a first voltage timing, a second voltage timing, a third voltage timing, a fourth voltage timing, and a fifth voltage timing. The step of timing the time between the rising and falling edges of the square waves in the first, second, and third voltage signals to obtain the voltage timing includes:

[0010] The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the first voltage timing time.

[0011] The time between the rising edge of the first square wave and the rising edge of the second square wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the second voltage timing time;

[0012] The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the third voltage timing time.

[0013] The time between the rising edge of the first square wave and the third rising edge of the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the fourth voltage timing time.

[0014] The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the fifth voltage timing time.

[0015] In one embodiment, detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes:

[0016] The conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler are calculated based on the voltage timing time.

[0017] The phase sequence of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage is detected based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler.

[0018] In one embodiment, detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes:

[0019] The conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler are calculated based on the voltage timing time.

[0020] Based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler, calculate the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage.

[0021] In one embodiment, calculating the voltage values ​​of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler includes:

[0022] Substituting the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler into the standard sine curve expression, we obtain the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage.

[0023] In one embodiment, detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes:

[0024] Calculate the time difference between the midpoints of adjacent voltage signals among the first voltage signal, the second voltage signal, and the third voltage signal based on the voltage timing.

[0025] Based on the time difference at the midpoint, detect whether the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage are missing a phase.

[0026] Secondly, this application also provides a three-phase AC voltage detection device. The device includes:

[0027] A voltage signal acquisition module is used to acquire a first voltage signal, a second voltage signal, and a third voltage signal; the first voltage signal comes from a first optocoupler, which is connected to a first phase AC voltage through a first current limiting circuit; the second voltage signal comes from a second optocoupler, which is connected to a second phase AC voltage through a second current limiting circuit; the third voltage signal comes from a third optocoupler, which is connected to a third phase AC voltage through a third current limiting circuit.

[0028] The timing module is used to time the time between the rising edge and the falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal, to obtain the voltage timing time.

[0029] The voltage detection module is used to detect the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage based on the voltage timing time.

[0030] Thirdly, this application also provides a three-phase AC voltage detection device, including a first current limiting circuit, a second current limiting circuit, a third current limiting circuit, a first optocoupler, a second optocoupler, a third optocoupler, and a controller. The input side of the first optocoupler is connected to the first current limiting circuit, the input side of the second optocoupler is connected to the second current limiting circuit, the input side of the third optocoupler is connected to the third current limiting circuit, and the output sides of the first optocoupler, the second optocoupler, and the third optocoupler are all connected to the controller.

[0031] The first optocoupler is connected to the first phase AC voltage through the first current limiting circuit and transmitted to the controller. The second optocoupler is connected to the second phase AC voltage through the second current limiting circuit and transmitted to the controller. The third optocoupler is connected to the third phase AC voltage through the third current limiting circuit and transmitted to the controller. The controller detects the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage according to the above method.

[0032] Fourthly, this application also provides an electrical system, including electrical equipment and a three-phase AC voltage detection device as described above.

[0033] The aforementioned three-phase AC voltage detection method, device, equipment, and power system first acquire a first voltage signal, a second voltage signal, and a third voltage signal. The first voltage signal comes from a first optocoupler, which is connected to the first phase AC voltage through a first current-limiting circuit. The second voltage signal comes from a second optocoupler, which is connected to the second phase AC voltage through a second current-limiting circuit. The third voltage signal comes from a third optocoupler, which is connected to the third phase AC voltage through a third current-limiting circuit. Then, the time between the rising and falling edges of the square waves in the first, second, and third voltage signals is timed to obtain the voltage timing time. The first, second, and third phase AC voltages are then detected based on the voltage timing time. This method, based on the acquired first, second, and third voltage signals, obtains the voltage timing time, thereby realizing the detection of three-phase AC voltage. The detection of three-phase AC voltage can be achieved through a single microcontroller pin, saving microcontroller pin resources and improving detection efficiency. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a three-phase AC voltage detection method in one embodiment;

[0035] Figure 2 This is a schematic diagram of the structure of a three-phase AC voltage detection device in one embodiment;

[0036] Figure 3 This is a schematic diagram of the process for obtaining voltage timing in one embodiment;

[0037] Figure 4 This is a schematic diagram of the voltage timing and optocoupler conduction time in one embodiment;

[0038] Figure 5 This is a schematic diagram of the process for detecting the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage in one embodiment;

[0039] Figure 6 This is a schematic diagram of the process for detecting the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage in another embodiment;

[0040] Figure 7 This is a flowchart illustrating the detection of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage in yet another embodiment.

[0041] Figure 8 This is a flowchart illustrating the detection of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage in another embodiment.

[0042] Figure 9 This is a structural block diagram of a three-phase AC voltage detection device in one embodiment;

[0043] Figure 10 This is a detailed flowchart of a three-phase AC voltage detection method in one embodiment;

[0044] Figure 11 This is a schematic diagram illustrating the time difference between the midpoints of a square wave in one embodiment.

[0045] Figure 12 A detailed flowchart of a three-phase AC voltage detection method in another embodiment;

[0046] Figure 13 This is a schematic diagram illustrating the relationship between the on-state voltage and time of an optocoupler in one embodiment. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0048] The three-phase AC voltage detection method provided in this application is used to detect three-phase AC voltage. The three-phase AC voltage includes a first-phase AC voltage, a second-phase AC voltage, and a third-phase AC voltage. The first-phase, second-phase, and third-phase AC voltages have the same frequency, equal potential amplitude, and a phase difference of 120° between them. The three-phase AC voltage detection method can be executed by a controller, which can be a microcontroller.

[0049] In one embodiment, such as Figure 1 As shown, a three-phase AC voltage detection method is provided, including the following steps:

[0050] Step 102: Obtain the first voltage signal, the second voltage signal, and the third voltage signal.

[0051] The first voltage signal comes from the first optocoupler U8, which is connected to the first phase AC voltage through the first current limiting circuit 110; the second voltage signal comes from the second optocoupler U12, which is connected to the second phase AC voltage through the second current limiting circuit 120; and the third voltage signal comes from the third optocoupler U13, which is connected to the third phase AC voltage through the third current limiting circuit 130.

[0052] like Figure 2 As shown, the input side of the first optocoupler U8 is connected to the first current limiting circuit 110, the input side of the second optocoupler U12 is connected to the second current limiting circuit 120, and the input side of the third optocoupler U13 is connected to the third current limiting circuit 130. The output sides of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 are all connected to the controller, and all are connected to the same pin of the controller, such as the Port pin. This allows the controller to receive the first voltage signal, the second voltage signal, and the third voltage signal at a single pin, and then process the received three voltage signals, saving the controller's pin resources.

[0053] The first optocoupler U8 is connected to the first phase AC voltage through the first current limiting circuit 110 and outputs a first voltage signal to the controller. The second optocoupler U12 is connected to the second phase AC voltage through the second current limiting circuit 120 and outputs a second voltage signal to the controller. The third optocoupler U13 is connected to the third phase AC voltage through the third current limiting circuit 130 and outputs a third voltage signal to the controller. Specifically, the side of the first current limiting circuit 110 not connected to the first optocoupler U8, the side of the second current limiting circuit 120 not connected to the second optocoupler U12, and the side of the third current limiting circuit 130 not connected to the third optocoupler U13 can all be connected to an air conditioner. They can also be connected to an air conditioner through a data interface to receive the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage from the air conditioner, respectively.

[0054] After the first current limiting circuit 110 receives the first phase AC voltage, it limits the current of the received first phase AC voltage and transmits it to the first optocoupler U8. The first optocoupler U8 turns on when the first phase AC voltage received on the input side is greater than the optocoupler's turn-on voltage, or when the received current is greater than the optocoupler's turn-on current. The first optocoupler U8 outputs a first voltage signal to the controller on the output side.

[0055] After the second phase AC voltage is connected to the second current limiting circuit 120, the second phase AC voltage is current-limited and then transmitted to the second optocoupler U12. The second optocoupler U12 conducts when the second phase AC voltage connected to the input side is greater than the optocoupler's turn-on voltage, or when the connected current is greater than the optocoupler's turn-on current. The second optocoupler U12 outputs a second voltage signal to the controller on the output side.

[0056] After the third phase AC voltage is connected to the third current limiting circuit 130, the current limiting circuit limits the connected third phase AC voltage before transmitting it to the third optocoupler U13. The third optocoupler U13 conducts when the third phase AC voltage connected to the input side is greater than the optocoupler's turn-on voltage, or when the connected current is greater than the optocoupler's turn-on current. The third optocoupler U13 outputs a third voltage signal to the controller on the output side.

[0057] Furthermore, the first current limiting circuit 110, the second current limiting circuit 120, and the third current limiting circuit 130 have different current limiting degrees for the input voltage. Since the first current limiting circuit 110, the second current limiting circuit 120, and the third current limiting circuit 130 have different current limiting degrees for the input voltage, and the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 have the same conduction current, the square wave outputs by the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 have the same period, but different widths. The controller will receive three square waves with different pulse widths, namely the first voltage signal, the second voltage signal, and the third voltage signal.

[0058] Step 104: The time between the rising edge and falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the voltage timing time.

[0059] Specifically, the first, second, and third voltage signals are all square wave signals. Upon receiving these signals, the controller detects the falling and rising edges of the square waves, triggering an interrupt and starting a timer to calculate the voltage timing. The voltage timing includes the time between the rising and falling edges, as well as the time between the rising edge and the rising and falling edges of the subsequent square waves.

[0060] Step 106: Detect the AC voltage of the first phase, the AC voltage of the second phase, and the AC voltage of the third phase based on the voltage timing time.

[0061] After obtaining the voltage timing time, the first-phase AC voltage, second-phase AC voltage, and third-phase AC voltage can be detected based on the voltage timing time. Specifically, since the voltage timing time includes the time between the rising edge and the falling edge, information such as the pulse width and phase of the square wave can be obtained from the voltage timing time. Based on this information, the time and position of the square wave can be determined, thereby determining whether the phase sequence of the first-phase AC voltage, second-phase AC voltage, and third-phase AC voltage is normal, or whether a phase is missing, thus realizing the detection of the first-phase AC voltage, second-phase AC voltage, and third-phase AC voltage.

[0062] In the above three-phase AC voltage detection method, a first voltage signal, a second voltage signal, and a third voltage signal are first acquired. The first voltage signal comes from a first optocoupler U8, which is connected to the first phase AC voltage through a first current limiting circuit 110. The second voltage signal comes from a second optocoupler U12, which is connected to the second phase AC voltage through a second current limiting circuit 120. The third voltage signal comes from a third optocoupler U13, which is connected to the third phase AC voltage through a third current limiting circuit 130. Then, the time between the rising and falling edges of the square waves in the first, second, and third voltage signals is timed to obtain the voltage timing time. The first, second, and third phase AC voltages are then detected based on the voltage timing time. This method, based on the acquired first, second, and third voltage signals, obtains the voltage timing time, thereby realizing the detection of three-phase AC voltage. The detection of three-phase AC voltage can be achieved through a single microcontroller pin, saving microcontroller pin resources and improving detection efficiency.

[0063] In one embodiment, the voltage timing time includes a first voltage timing time, a second voltage timing time, a third voltage timing time, a fourth voltage timing time, and a fifth voltage timing time, such as... Figure 3 As shown, step 104 includes steps 304 to 308.

[0064] Step 304: The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the first voltage timing time.

[0065] Step 305: The time between the rising edge of the first square wave and the second rising edge of the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the second voltage timing time.

[0066] Step 306: The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the timing time of the third voltage.

[0067] Step 307: The time between the rising edge of the first square wave and the rising edge of the third voltage wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the fourth voltage timing time.

[0068] Step 308: The time between the rising edge of the first square wave and the falling edge of the third voltage wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the fifth voltage timing time.

[0069] The controller can identify the rising and falling edges of a square wave. When the controller detects the falling and rising edges of the square wave, the program enters an interrupt, starts a timer, and obtains the voltage timing time. For example, Figure 4 As shown, the time between the rising edge and the falling edge of the first square wave is timed to obtain the first voltage timing time, denoted as T1. The time between the rising edge and the second rising edge of the first square wave is timed to obtain the second voltage timing time, denoted as T2. The time between the rising edge and the second falling edge of the first square wave is timed to obtain the third voltage timing time, denoted as T3. The time between the rising edge and the third rising edge of the first square wave is timed to obtain the fourth voltage timing time, denoted as T4. The time between the rising edge and the third falling edge of the first square wave is timed to obtain the fifth voltage timing time, denoted as T5. Based on the first, second, third, fourth, and fifth voltage timing times, the times of the rising and falling edges of the three square wave signals within a complete cycle can be obtained, thus obtaining the complete three-phase AC voltage signal.

[0070] In one embodiment, such as Figure 5 As shown, step 106 includes steps 506 and 507.

[0071] Step 506: Calculate the conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler based on the voltage timing time.

[0072] The voltage timing time is the time between the rising and falling edges of the square wave, including the positions where the rising and falling edges occur. The conduction time of the first optocoupler U8 is the time between the first rising and first falling edges of the square wave, the conduction time of the second optocoupler U12 is the time between the second rising and second falling edges of the square wave, and the conduction time of the third optocoupler U13 is the time between the third rising and third falling edges of the square wave. Therefore, the conduction times of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 are calculated based on the voltage timing time.

[0073] For example, when the voltage timing time includes the first voltage timing time, the second voltage timing time, the third voltage timing time, the fourth voltage timing time, and the fifth voltage timing time, the conduction time of the first optocoupler U8 is equal to the first voltage timing time, the conduction time of the second optocoupler U12 is the difference between the third voltage timing time and the second voltage timing time, and the conduction time of the third optocoupler U13 is the difference between the fifth voltage timing time and the fourth voltage timing time.

[0074] Step 507: Detect whether the phase sequence of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage is normal based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler.

[0075] Specifically, the phase sequence of the first, second, and third phase AC voltages can be determined by judging the conduction times of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13. Generally, the conduction time of the first optocoupler U8 is longer than that of the second optocoupler U12, and the conduction time of the second optocoupler U12 is longer than that of the third optocoupler U13. Therefore, if the conduction times of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 are not in this order, an abnormal phase sequence is considered. In this case, a shutdown command can be further sent to the electrical equipment connected to the current-limiting circuit, such as sending a stop command to an air conditioner. The shutdown command is used to control the electrical equipment to stop operating, preventing damage to the equipment caused by abnormal three-phase AC voltage.

[0076] Furthermore, when an abnormal phase sequence is detected in the first, second, and third phase AC voltages, a phase loss fault can be reported to the host computer, which can be a server or a client terminal, to remind the user to handle the abnormal situation promptly. Moreover, when an abnormal phase sequence is detected in the first, second, and third phase AC voltages, the fault code for the abnormal phase sequence can be saved in the controller's storage medium for subsequent processing.

[0077] The above-described method for detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage can detect whether the phase sequence of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage is normal through a single controller pin, thereby achieving three-phase AC voltage phase sequence detection.

[0078] In one embodiment, such as Figure 6 As shown, step 106 includes steps 606 and 608.

[0079] Step 606: Calculate the conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler based on the voltage timing time.

[0080] The voltage timing time is the time between the rising and falling edges of the square wave, including the positions where the rising and falling edges occur. The conduction time of the first optocoupler U8 is the time between the first rising and first falling edges of the square wave, the conduction time of the second optocoupler U12 is the time between the second rising and second falling edges of the square wave, and the conduction time of the third optocoupler U13 is the time between the third rising and third falling edges of the square wave. Therefore, the conduction times of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 are calculated based on the voltage timing time.

[0081] For example, when the voltage timing includes a first voltage timing, a second voltage timing, a third voltage timing, a fourth voltage timing, and a fifth voltage timing, the conduction time of the first optocoupler U8 is equal to the first voltage timing, the conduction time of the second optocoupler U12 is the difference between the third and second voltage timing, and the conduction time of the third optocoupler U13 is the difference between the fifth and fourth voltage timing. This step is the same as step 406 in the previous embodiment.

[0082] Step 608: Calculate the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler.

[0083] Let I represent the conduction current of the optocoupler. The optocoupler conducts when the current connected to it is greater than I. As the voltage of the first phase AC voltage, the second phase AC voltage, or the third phase AC voltage changes sinusoidally, the current flowing through the optocoupler also changes. The conduction current of each optocoupler is equal, but the current flowing through each optocoupler is not equal.

[0084] The first, second, and third phase AC voltages are generally sinusoidal curves. The expression for the first phase AC voltage can be solved using the on-state voltage and corresponding on-time of the first optocoupler U8, thus obtaining its voltage value. Similarly, the expression for the second phase AC voltage can be solved using the on-state voltage and corresponding on-time of the second optocoupler U12, thus obtaining its voltage value. The expression for the third phase AC voltage can be solved using the on-state voltage and corresponding on-time of the third optocoupler U13, thus obtaining its voltage value.

[0085] The method described above for detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage can calculate the voltage values ​​of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage through a single controller pin.

[0086] In one embodiment, such as Figure 7 As shown, step 608 includes step 708.

[0087] Step 708: Substitute the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler into the standard sinusoidal curve expression to obtain the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage.

[0088] Specifically, taking the calculation of the first phase AC voltage based on the conduction time and conduction voltage of the first optocoupler U8 as an example, when the current flowing through the first optocoupler U8 is greater than the conduction current of the first optocoupler U8, the first optocoupler U8 conducts and outputs a square wave. Therefore, the conduction voltage Uron = Ir * R is derived; where Uron is the conduction voltage of the optocoupler, Ir is the current flowing through the first optocoupler U8, and R is the equivalent resistance of the first current limiting circuit 110.

[0089] The phase difference between the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage is 120 degrees. Each 120 degrees is T, and one cycle is 360 degrees, which is 3T.

[0090] The standard sinusoidal curve expression is y = Asin(wx + φ), with a period of 3T. After calculating the conduction time of the first optocoupler U8, to simplify the calculation, let φ = 0, resulting in y = Asin(wx). Substituting this into the point (x, y) ((3T / 4 - Tr / 2), Uron), we can find the value of A, where Tr is the conduction time of the first optocoupler U8. Then, the first phase AC voltage Ur = A / 1.414. Similarly, the second phase AC voltage can be calculated based on the conduction time and voltage of the second optocoupler U12, and the third phase AC voltage can be calculated based on the conduction time and voltage of the third optocoupler U13. The specific process is similar to that of calculating the first phase AC voltage and will not be repeated here.

[0091] In one embodiment, such as Figure 8 As shown, step 106 includes steps 806 and 808.

[0092] Step 806: Calculate the time difference between the midpoints of adjacent voltage signals among the first, second, and third voltage signals based on the voltage timing.

[0093] The time difference between the midpoints of adjacent voltage signals among the first, second, and third voltage signals refers to the time difference between the midpoint of the square wave of the first voltage signal and the midpoint of the square wave of the second voltage signal, or the time difference between the midpoint of the square wave of the second voltage signal and the midpoint of the square wave of the third voltage signal.

[0094] With T 中 Let T represent the time difference between the midpoints of adjacent voltage signals among the first, second, and third voltage signals. Then, based on the voltage timing, the time difference between the midpoints of adjacent voltage signals among the first, second, and third voltage signals can be calculated as: T 中 =T5 / 3, where T5 is the fifth voltage timing time. It is understood that in other embodiments, the time difference between the midpoints of adjacent voltage signals among the first, second, and third voltage signals can also be calculated based on other voltage timing times, provided that it is feasible for those skilled in the art.

[0095] Step 808: Detect whether the first phase AC voltage, second phase AC voltage, and third phase AC voltage are missing based on the time difference at the midpoint.

[0096] After obtaining the time difference at the midpoint, three times that time difference is the period of the three-phase AC voltage. By determining the number of square waves within the period of the three-phase AC voltage, it can be determined whether the first, second, and third phases of the AC voltage are missing a phase. For example, if there are three square waves within the period of the three-phase AC voltage, it is considered that the first, second, and third phases of the AC voltage are not missing a phase. If there are two or one square wave within the period of the three-phase AC voltage, it is considered that the first, second, and third phases of the AC voltage are missing a phase.

[0097] The above-described method for detecting the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage can detect whether the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage are missing through a single controller pin, thereby achieving three-phase AC voltage phase loss detection.

[0098] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0099] Based on the same inventive concept, this application also provides a three-phase AC voltage detection device for implementing the three-phase AC voltage detection method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the three-phase AC voltage detection device provided below can be found in the limitations of the three-phase AC voltage detection method described above, and will not be repeated here.

[0100] In one embodiment, such as Figure 9 As shown, a three-phase AC voltage detection device is provided, including: a voltage signal acquisition module 910, a timing module 920, and a voltage detection module 930, wherein:

[0101] The voltage signal acquisition module 910 is used to acquire a first voltage signal, a second voltage signal, and a third voltage signal; the first voltage signal comes from the first optocoupler U8, which is connected to the first phase AC voltage through the first current limiting circuit 110; the second voltage signal comes from the second optocoupler U12, which is connected to the second phase AC voltage through the second current limiting circuit 120; the third voltage signal comes from the third optocoupler U13, which is connected to the third phase AC voltage through the third current limiting circuit 130.

[0102] The timing module 920 is used to time the time between the rising edge and the falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal, so as to obtain the voltage timing time.

[0103] The voltage detection module 930 is used to detect the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage based on the voltage timing time.

[0104] Each module in the aforementioned three-phase AC voltage detection device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0105] In one embodiment, a three-phase AC voltage detection device is provided, such as... Figure 2 As shown, the circuit includes a first current limiting circuit 110, a second current limiting circuit 120, a third current limiting circuit 130, a first optocoupler U8, a second optocoupler U12, a third optocoupler U13, and a controller. The input side of the first optocoupler U8 is connected to the first current limiting circuit 110, the input side of the second optocoupler U12 is connected to the second current limiting circuit 120, and the input side of the third optocoupler U13 is connected to the third current limiting circuit 130. The output sides of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 are all connected to the controller.

[0106] The first optocoupler U8 is connected to the first phase AC voltage through the first current limiting circuit 110 and transmitted to the controller. The second optocoupler U12 is connected to the second phase AC voltage through the second current limiting circuit 120 and transmitted to the controller. The third optocoupler U13 is connected to the third phase AC voltage through the third current limiting circuit 130 and transmitted to the controller. The controller detects the first, second, and third phase AC voltages according to the above method. The controller can be a control chip in the electrical equipment connected to the three-phase AC voltage detection device to save hardware costs, or it can be a standalone controller for ease of use.

[0107] In one embodiment, such as Figure 2 As shown, the first current-limiting circuit 110 includes a first diode D5 and a first current-limiting resistor R28. The anode of the first diode D5 is used to connect to the first phase AC voltage, and the cathode of the first diode D5 is connected to the input side of the first optocoupler U8 through the first current-limiting resistor R28. The second current-limiting circuit 120 includes a second diode D7 and a second current-limiting resistor R35. The anode of the second diode D7 is used to connect to the second phase AC voltage, and the cathode of the second diode D7 is connected to the input side of the second optocoupler U12 through the second current-limiting resistor R35. The third current-limiting circuit 130 includes a third diode D9 and a third current-limiting resistor R40. The anode of the third diode D9 is used to connect to the third phase AC voltage, and the cathode of the third diode D9 is connected to the input side of the third optocoupler U13 through the third current-limiting resistor R40.

[0108] The negative voltage in the first phase AC voltage is filtered out by the first diode D5, and the positive voltage is transmitted to the input side of the first optocoupler U8 after passing through the first current-limiting resistor R28. The negative voltage in the second phase AC voltage is filtered out by the second diode D7, and the positive voltage is transmitted to the input side of the second optocoupler U12 after passing through the second current-limiting resistor R35. The negative voltage in the third phase AC voltage is filtered out by the third diode D9, and the positive voltage is transmitted to the input side of the third optocoupler U13 after passing through the third current-limiting resistor R40.

[0109] Because the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 have the same on-state current, and the first current-limiting resistor R28, the second current-limiting resistor R35, and the third current-limiting resistor R40 have different resistance values, the currents flowing through them are different. Therefore, the square waves output by the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 have the same period, but different widths. Consequently, the pins of the controller connected to the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 will receive three square waves with different pulse widths. By detecting the timing of these three square waves, the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage can be detected.

[0110] In one embodiment, an electrical system is provided, including electrical equipment and a three-phase AC voltage detection device as described above. The electrical equipment is connected to the three-phase AC voltage detection device, which can detect the three-phase AC voltage of the electrical equipment.

[0111] To better understand the above embodiments, a detailed explanation is provided below with reference to a specific embodiment. In one embodiment, as follows... Figure 2 As shown, the three-phase AC voltage detection device includes a first current limiting circuit 110, a second current limiting circuit 120, a third current limiting circuit 130, a first optocoupler U8, a second optocoupler U12, a third optocoupler U13, and a controller. The controller is used to execute the three-phase AC voltage detection method in the above embodiment.

[0112] The three-phase AC voltage detection device also includes a first output control circuit 210, a second output control circuit 220, and a third output control circuit 230. The first output control circuit 210 connects the output side of the first optocoupler U8 to the common terminal of the controller; the second output control circuit 220 connects the output side of the second optocoupler U12 to the common terminal of the controller; and the third output control circuit 230 connects the output side of the third optocoupler U13 to the common terminal of the controller. The first output control circuit 210, the second output control circuit 220, and the third output control circuit 230 can process the output voltages of the first optocoupler U8, the second optocoupler U12, and the third optocoupler U13 respectively, improving signal quality.

[0113] Specifically, the first output control circuit 210 includes resistors R29 and R30 and capacitor C19. The first ends of resistors R29 and R30 are both connected to the output terminal of the first optocoupler U8. The second end of resistor R29 is connected to the power supply. The second end of resistor R30 is connected to the controller. The first end of capacitor C19 is connected to the common terminal of the second end of resistor R30 and the controller. The second end of capacitor C19 is grounded.

[0114] The second output control circuit 220 includes resistors R36 and R37 and capacitor C21. The first ends of resistors R36 and R37 are both connected to the output end of the first optocoupler U8. The second end of resistor R36 is connected to the power supply. The second end of resistor R37 is connected to the controller. The first end of capacitor C21 is connected to the common terminal of the second end of resistor R37 and the controller. The second end of capacitor C21 is grounded.

[0115] The third output control circuit 230 includes resistors R41 and R43 and capacitor C22. The first ends of resistors R41 and R43 are both connected to the output end of the first optocoupler U8. The second end of resistor R41 is connected to the power supply. The second end of resistor R43 is connected to the controller. The first end of capacitor C22 is connected to the common terminal of the second end of resistor R43 and the controller. The second end of capacitor C22 is grounded.

[0116] The first current limiting circuit 110 includes a first diode D5 and a first current limiting resistor R28, the second current limiting circuit 120 includes a second diode D7 and a second current limiting resistor R35, and the third current limiting circuit 130 includes a third diode D9 and a third current limiting resistor R40.

[0117] Taking an air conditioner as an example, the three-phase AC voltage detection device also includes terminal CN2, which is connected to the power cord of the air conditioner, diodes D5, D7 and D9. The controller can be the control chip of the air conditioner, specifically a microcontroller. The port pin of the control chip of the air conditioner is connected to resistors R30, R37 and R43.

[0118] The negative voltages in the first, second, and third phase AC voltages are filtered out by the unidirectional conduction of diodes D5, D7, and D9. Since the resistance values ​​of resistors R28, R35, and R40 are different, the conduction current of the optocoupler is the same, resulting in the same period of the output square wave, but different widths. Therefore, three square waves with different pulse widths will be received at the Port pin. The time points in the figure are obtained by detecting the time of each of these three square waves.

[0119] The microcontroller enters an interrupt by recognizing the falling and rising edges of the square wave, and starts the timer. Figure 4In the diagram, T1 is the time from the rising edge to the falling edge of the first square wave, T2 is the time from the first rising edge to the second rising edge, T3 is the time from the first rising edge to the second falling edge, T4 is the time from the first rising edge to the third rising edge, T5 is the time from the first rising edge to the third falling edge, T6 is the time from the first rising edge to the fourth rising edge, Tr is the time when the first optocoupler U8 is turned on, Ts is the time when the second optocoupler U12 is turned on, and Tt is the time when the third optocoupler U13 is turned on.

[0120] like Figure 10 As shown, after the air conditioner is powered on, the times T1, T2, T3, T4, and T5 are acquired, and then the times Tr, Ts, and Tt are calculated. Because the resistance values ​​of resistors R28, R35, and R40 are different, the times Tr, Ts, and Tt are also different, appearing in descending order. If the acquired times are not in descending order, it indicates a phase sequence problem. Specifically, the phase sequence is determined by comparing the durations of Tr, Ts, and Tt. If Tr > Ts > Tt, the three-phase AC voltage phase sequence is abnormal. In this case, the unit can be immediately shut down and a phase sequence abnormality fault report can be issued, with the fault code saved in the storage medium.

[0121] In addition, such as Figure 11 and 12 As shown, after acquiring the times T1, T2, T3, T4, and T5, the controller calculates the time difference T between the intermediate points based on the measured times. 中 T 中 =T5 / 3. Then, based on the time difference at the center point, determine whether the three-phase voltage is missing a phase. Specifically, determine whether the three-phase voltage is missing a phase by judging the number of square waves within 3T. If a phase is missing, immediately control the machine to stop and report a phase loss fault, and save the fault code in the storage medium.

[0122] Furthermore, when the current flowing through the first optocoupler U8 is greater than the conduction current of the first optocoupler U8, the first optocoupler U8 conducts and outputs a square wave. Therefore, the conduction voltage Uron = Ir * R is derived. The conduction voltage refers to the voltage at a certain moment when the optocoupler outputs the rising or falling edge of a sinusoidal voltage. Where Uron is the conduction voltage of the optocoupler, Ir is the current flowing through the first optocoupler U8, and R is the equivalent resistance of the first current-limiting circuit 110.

[0123] The phase difference between the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage is 120 degrees. Each 120 degrees is T, and one cycle is 360 degrees, which is 3T.

[0124] like Figure 13As shown, the standard sinusoidal curve expression is y = Asin(wx + φ), with a period of 3T. After calculating the conduction time of the first optocoupler U8, to simplify the calculation, let φ = 0, resulting in y = Asin(wx). Substituting the value of A into the point (x, y) ((3T / 4 - Tr / 2), Uron), where Tr is the conduction time of the first optocoupler U8, the first phase AC voltage Ur = A / 1.414. Following a similar method, the second and third phase AC voltages can be calculated. The specific process is similar to that of calculating the first phase AC voltage, and will not be repeated here.

[0125] The aforementioned three-phase AC voltage detection device can detect the phase sequence, phase loss, and voltage value of three-phase AC voltage using only one controller pin, without occupying too much of the controller's external interrupt resources and pin resources.

[0126] The aforementioned three-phase AC voltage detection method, device, equipment, and power system first acquire a first voltage signal, a second voltage signal, and a third voltage signal. The first voltage signal comes from a first optocoupler U8, which is connected to the first phase AC voltage through a first current limiting circuit 110. The second voltage signal comes from a second optocoupler U12, which is connected to the second phase AC voltage through a second current limiting circuit 120. The third voltage signal comes from a third optocoupler U13, which is connected to the third phase AC voltage through a third current limiting circuit 130. Then, the time between the rising and falling edges of the square waves in the first, second, and third voltage signals is timed to obtain the voltage timing time. The first, second, and third phase AC voltages are then detected based on the voltage timing time. This method, based on the acquired first, second, and third voltage signals, obtains the voltage timing time, thereby realizing the detection of three-phase AC voltage. The detection of three-phase AC voltage can be achieved through a single microcontroller pin, saving microcontroller pin resources and improving detection efficiency.

[0127] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0128] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0129] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0130] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0131] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for detecting three-phase AC voltage, characterized in that, The method includes: A first voltage signal, a second voltage signal, and a third voltage signal are acquired at a single pin. The first voltage signal originates from a first optocoupler, which is connected to a first-phase AC voltage via a first current-limiting circuit. The second voltage signal originates from a second optocoupler, which is connected to a second-phase AC voltage via a second current-limiting circuit. The third voltage signal originates from a third optocoupler, which is connected to a third-phase AC voltage via a third current-limiting circuit. The first, second, and third current-limiting circuits limit the current of the connected voltages to different degrees. The first, second, and third optocouplers have the same on-state current. The voltage timing time is obtained by timing the time between the rising edge and the falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal; The first phase AC voltage, the second phase AC voltage, and the third phase AC voltage are detected based on the voltage timing time.

2. The method according to claim 1, characterized in that, The voltage timing includes a first voltage timing, a second voltage timing, a third voltage timing, a fourth voltage timing, and a fifth voltage timing. The step of timing the time between the rising and falling edges of the square waves in the first, second, and third voltage signals to obtain the voltage timing includes: The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the first voltage timing time. The time between the rising edge of the first square wave and the rising edge of the second square wave in the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the second voltage timing time; The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the third voltage timing time. The time between the rising edge of the first square wave and the third rising edge of the first voltage signal, the second voltage signal and the third voltage signal is timed to obtain the fourth voltage timing time. The time between the rising edge and the falling edge of the first square wave in the first voltage signal, the second voltage signal, and the third voltage signal is timed to obtain the fifth voltage timing time.

3. The method according to claim 1, characterized in that, The detection of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes: The conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler are calculated based on the voltage timing time. The phase sequence of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage is detected based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler.

4. The method according to claim 1, characterized in that, The detection of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes: The conduction time of the first optocoupler, the conduction time of the second optocoupler, and the conduction time of the third optocoupler are calculated based on the voltage timing time. Based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler, calculate the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage.

5. The method according to claim 4, characterized in that, The step of calculating the voltage values ​​of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler includes: Substituting the conduction time of the first optocoupler, the conduction time of the second optocoupler, the conduction time of the third optocoupler, the conduction voltage of the first optocoupler, the conduction voltage of the second optocoupler, and the conduction voltage of the third optocoupler into the standard sine curve expression, we obtain the voltage values ​​of the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage.

6. The method according to claim 1, characterized in that, The detection of the first-phase AC voltage, the second-phase AC voltage, and the third-phase AC voltage based on the voltage timing time includes: Calculate the time difference between the midpoints of adjacent voltage signals among the first voltage signal, the second voltage signal, and the third voltage signal based on the voltage timing. Based on the time difference at the midpoint, detect whether the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage are missing a phase.

7. A three-phase AC voltage detection device, characterized in that, The device includes: A voltage signal acquisition module is used to acquire a first voltage signal, a second voltage signal, and a third voltage signal; the first voltage signal comes from a first optocoupler, which is connected to a first phase AC voltage through a first current limiting circuit; the second voltage signal comes from a second optocoupler, which is connected to a second phase AC voltage through a second current limiting circuit; the third voltage signal comes from a third optocoupler, which is connected to a third phase AC voltage through a third current limiting circuit. The timing module is used to time the time between the rising edge and the falling edge of the square wave in the first voltage signal, the second voltage signal and the third voltage signal, to obtain the voltage timing time. The voltage detection module is used to detect the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage based on the voltage timing time.

8. A three-phase AC voltage detection device, characterized in that, The device includes a first current limiting circuit, a second current limiting circuit, a third current limiting circuit, a first optocoupler, a second optocoupler, a third optocoupler, and a controller. The input side of the first optocoupler is connected to the first current limiting circuit, the input side of the second optocoupler is connected to the second current limiting circuit, the input side of the third optocoupler is connected to the third current limiting circuit, and the output sides of the first optocoupler, the second optocoupler, and the third optocoupler are all connected to the controller. The first optocoupler is connected to the first phase AC voltage through the first current limiting circuit and transmitted to the controller; the second optocoupler is connected to the second phase AC voltage through the second current limiting circuit and transmitted to the controller; the third optocoupler is connected to the third phase AC voltage through the third current limiting circuit and transmitted to the controller; the controller detects the first phase AC voltage, the second phase AC voltage, and the third phase AC voltage according to the method of any one of claims 1-6.

9. The three-phase AC voltage detection device according to claim 8, characterized in that, The first current limiting circuit includes a first diode and a first current limiting resistor. The anode of the first diode is used to connect to the first phase AC voltage, and the cathode of the first diode is connected to the input side of the first optocoupler through the first current limiting resistor. The second current limiting circuit includes a second diode and a second current limiting resistor. The anode of the second diode is used to connect to the second phase AC voltage, and the cathode of the second diode is connected to the input side of the second optocoupler through the second current limiting resistor. The third current-limiting circuit includes a third diode and a third current-limiting resistor. The anode of the third diode is used to connect to the third phase AC voltage, and the cathode of the third diode is connected to the input side of the third optocoupler through the third current-limiting resistor.

10. An electrical system, characterized in that, This includes electrical equipment and the three-phase AC voltage detection device as described in claim 8.

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