Three-phase AC input power supply open-phase detection circuit, system and method

Abstract

The invention provides an open-phase detection circuit for a three-phase alternating-current input power supply. The open-phase detection circuit comprises a rectifying module, a coupling module and a charging and discharging module, wherein the rectification module is electrically connected with a three-phase alternating current power supply so as to rectify and combine three-phase alternating current signals of the three-phase alternating current power supply into a combined rectification signal; the rectification module is electrically connected with the coupling module so as to couple and transmit the combined rectification signal to the charging and discharging module through the coupling module to obtain a charging and discharging signal; and the charging and discharging module performs charging and discharging processes under the charging and discharging signals to generate detection voltage, so that the detection voltage is obtained, and open-phase detection is performed based on the detection voltage and a preset normal range to obtain an open-phase detection result. According to the open-phase detection circuit, system and method for the three-phase alternating-current input power supply, open-phase detection is carried out through simple circuit rectification, coupling and charging and discharging, the cost of components is reduced, and the design of the open-phase detection circuit for the three-phase alternating-current power supply is simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit detection, and in particular to a three-phase AC input power supply phase loss detection circuit, system and method. Background Art

[0002] Traditional three-phase AC input PFC switching power supply phase loss detection methods are usually divided into the following two types: when the detection object is a three-phase four-wire AC input power supply, the N line of the four lines is generally required as a reference for the detection circuit, and after sampling the phase voltage, it can be determined whether there is a phase loss; when the detection object is a three-phase three-wire AC input power supply, it is necessary to additionally design a virtual N line reference point, or directly sample the line voltage, and then use DSP processing to determine whether there is a phase loss after obtaining the line voltage.

[0003] For three-phase four-wire and three-phase three-wire detection circuits, three identical detection circuits are generally required to detect the phase voltage or line voltage for phase loss judgment, and the operational amplifier of the detection circuit needs to be powered by negative voltage or increase DC bias, which makes the circuit design cumbersome and complicated, increases the cost and volume of components, and there are also problems such as the three-phase four-wire phase loss detection circuit cannot be applied to the three-phase three-wire AC input power supply circuit, and the input voltage detection range is reduced when the three-phase three-wire detection circuit directly samples the line voltage. Summary of the invention

[0004] The present invention aims to provide a three-phase AC input power phase loss detection circuit to solve the above technical problems and simplify the design of the three-phase AC input power phase loss detection circuit.

[0005] In order to solve the above technical problems, the present invention provides a three-phase AC input power supply phase loss detection circuit, comprising: a rectifier module, a coupling module and a charge and discharge module; wherein:

[0006] The rectifier module includes an input terminal for electrically connecting to a three-phase AC power source to rectify and combine the three-phase AC signals of the three-phase AC power source into a combined rectified signal;

[0007] The rectifier module is electrically connected to the first input terminal of the coupling module through the positive output terminal, and is electrically connected to the second input terminal of the coupling module through the negative input terminal. The first output terminal of the coupling module is electrically connected to the positive input terminal of the charge-discharge module, and the second output terminal is electrically connected to the negative input terminal of the charge-discharge module, so as to couple and transmit the combined rectifier signal to the charge-discharge module through the coupling module to obtain a charge-discharge signal.

[0008] The charge and discharge module contains a voltage detection interface. The charge and discharge module performs charging and discharging processes under the charge and discharge signal to generate a detection voltage, thereby obtaining the detection voltage through the voltage detection interface, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0009] The above scheme rectifies the three-phase AC power output into one signal through simple circuit rectification, coupling, and charging and discharging, without the need to design an additional virtual N-line reference point, to achieve phase loss detection in the three-phase AC circuit, thereby reducing component costs and avoiding excessive size of the detection circuit, thereby simplifying the design of the three-phase AC input power phase loss detection circuit.

[0010] Further, the rectifier module includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; wherein:

[0011] The anode of the first diode serves as the first input end of the rectifier module and is electrically connected to the first input end of the three-phase AC input power supply, and the anode of the first diode is electrically connected to the cathode of the fourth diode;

[0012] The anode of the second diode serves as the second input end of the rectifier module and is electrically connected to the second input end of the three-phase AC input power supply, and the anode of the second diode is electrically connected to the cathode of the fifth diode;

[0013] The anode of the third diode serves as the third input terminal of the rectifier module and is electrically connected to the third input terminal of the three-phase AC input power supply. The anode of the third diode is electrically connected to the cathode of the sixth diode.

[0014] The cathode of the first diode is electrically connected to the cathode of the second diode, the cathode of the second diode is electrically connected to the cathode of the third diode, and the cathode of the third diode serves as a positive output end of the rectifier module and is electrically connected to the first input end of the coupling module;

[0015] The anode of the fourth diode is electrically connected to the anode of the fifth diode, the anode of the fifth diode is electrically connected to the anode of the sixth diode, and the anode of the sixth diode serves as a negative output end of the rectifier module and is electrically connected to the second input end of the coupling module.

[0016] The above scheme forms a rectifier circuit through six diodes, and is connected to the power supply to be detected through different interfaces, so that the rectifier module receives each phase AC signal of the three-phase AC input power supply and rectifies it into one signal, providing a signal basis for the charging and discharging module to perform detection, and there is no need for three-way separate detection, which simplifies the detection circuit.

[0017] Furthermore, the coupling module includes an optical coupler, and the optical coupler includes a first input end, a second input end, a first output end, and a second output end; wherein:

[0018] The first input end of the optical coupler serves as the first input end of the coupling module and is electrically connected to the positive output end of the rectifier module;

[0019] The second input end of the optical coupler serves as the second input end of the coupling module and is electrically connected to the negative output end of the rectifier module;

[0020] The first output end of the optical coupler serves as the first output end of the coupling module and is electrically connected to the positive input end of the charge and discharge module;

[0021] The second output end of the optical coupler serves as the second output end of the coupling module and is electrically connected to the negative input end of the charge and discharge module.

[0022] In the above solution, the coupling module realizes signal transmission through an optical coupler to provide signals for the charging and discharging module.

[0023] Furthermore, the coupling module also includes: a current limiting resistor, wherein: a first end of the current limiting resistor is electrically connected to the positive output end of the rectifier module, and a second end of the current limiting resistor is electrically connected to the first input end of the optocoupler, so as to scale the combined rectified signal, so that the optocoupler is in a preset working state, and generates the required charge and discharge signals.

[0024] In the above scheme, the coupling module adjusts the combined rectified signal through the current limiting resistor to put the optical coupler in the best working state and lays the foundation for a simpler and more intuitive detection and analysis method for phase loss detection.

[0025] Furthermore, the charging and discharging module includes: a DC resistor, a seventh diode, a charging and discharging resistor and a detection capacitor; wherein:

[0026] The first end of the DC resistor is electrically connected to the anode of the seventh diode, and the second end of the DC resistor is electrically connected to the second end of the detection capacitor;

[0027] The cathode of the seventh diode is electrically connected to the first end of the charge and discharge resistor;

[0028] The first end of the charge-discharge resistor is electrically connected to the first end of the detection capacitor, and the second end of the charge-discharge resistor is electrically connected to the second end of the detection capacitor;

[0029] The anode of the seventh diode is used as the positive input terminal of the charge-discharge module and electrically connected to the first output terminal of the coupling module;

[0030] The second end of the charge-discharge resistor is used as a charge-discharge negative input end and is electrically connected to the second output end of the coupling module;

[0031] The two ends of the detection capacitor are used as the voltage detection interface.

[0032] In the above scheme, a charge and discharge circuit is designed through a DC resistor, a seventh diode, a charge and discharge capacitor and a detection capacitor, so that the charge and discharge module performs the charging and discharging process in a preset manner under the action of the charge and discharge signal, thereby performing phase loss detection based on the detection voltage generated at both ends of the detection capacitor, and the analysis of the detection results is simple and intuitive.

[0033] The above scheme designs the rectifier module, coupling module and charge and discharge module separately, and finally obtains a phase loss detection circuit with simple circuit, convenient and intuitive detection and analysis, which reduces the cost of components and avoids the detection circuit from being too large.

[0034] The present invention provides a three-phase AC input power supply phase loss detection system, comprising a three-phase AC input power supply phase loss detection circuit, a detection power supply unit and a result detection unit, wherein:

[0035] The detection power supply unit includes a three-phase AC input power supply required for detection, and is used to provide a three-phase AC signal for the phase loss detection circuit;

[0036] The phase loss detection circuit is used to rectify and merge the three-phase AC signal into a combined rectified signal through the rectifier module, and couple the combined rectified signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, so that the charge and discharge module performs a charging and discharging process under the charge and discharge signal to generate a detection voltage;

[0037] The result detection unit is used to obtain the detection voltage in real time, and perform phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0038] The phase loss detection system provided by the above scheme performs simple power signal rectification, coupling, charging and discharging through the phase loss detection circuit to realize the phase loss detection of the power supply, and provides a system with a simple and convenient structure for phase loss detection.

[0039] Furthermore, the phase loss detection circuit also includes: a device for rectifying and combining the three-phase AC signals into a combined rectified signal through a rectifier module, and performing current limiting based on the combined rectified signal to obtain a coupling signal, so as to couple the coupling signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, thereby enabling the charge and discharge module to perform a charging and discharging process under the charge and discharge signal to generate a detection voltage.

[0040] In the above scheme, the combined rectified signal is further processed so that the phase loss detection circuit is in a preset working state, so that the generated detection voltage result is more accurate and intuitive.

[0041] Furthermore, the phase loss detection system also includes: a result verification unit, which is used to adjust the coupling transmission parameters in the phase loss detection circuit according to a preset adjustment method, so that the phase loss detection circuit generates a new detection voltage based on the three-phase AC signal, so that the result detection unit performs phase loss detection based on the new detection voltage and a preset normal range to obtain a new phase loss detection result, so as to complete the result verification based on the phase loss detection result and the new phase loss detection result and obtain the final phase loss detection result.

[0042] The above scheme solves the problem of large errors in detection results caused by environmental factors in practical applications by adjusting parameters and re-verifying, thereby enhancing the robustness and reliability of the system.

[0043] The system proposed in the above scheme has a simple structure and is easy to implement. It obtains detection data through signal conversion processing through a simple phase loss detection circuit, and adjusts circuit parameters according to actual conditions during application to enhance the robustness and reliability of the detection circuit, making the system more reliable and improving detection accuracy.

[0044] The present invention also provides a three-phase AC input power supply phase loss detection method, which uses a three-phase AC input power supply phase loss detection system as described in the above scheme, comprising the following steps:

[0045] Performing rectification and merging based on three-phase AC signals of a three-phase AC power supply to obtain a combined rectified signal;

[0046] Based on the combined rectified signal, coupled transmission is performed to obtain the charging and discharging signal;

[0047] The charging and discharging process is performed based on the charge and discharge signal to generate a detection voltage, thereby obtaining the detection voltage in real time, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0048] The above scheme realizes the conversion of power supply AC signal through rectification and merging, coupled transmission and charging and discharging process, thereby realizing phase loss detection.

[0049] Further, the coupling transmission based on the combined rectified signal to obtain the charge and discharge signal includes: current limiting based on the combined rectified signal to obtain the coupling signal, and obtaining the charge and discharge signal based on the coupling signal.

[0050] The above solution adds a current limiting process to make the coupled transmission signal more in line with ideal requirements and provide a basis for simple and convenient phase loss detection.

[0051] The phase loss detection method provided in the above scheme realizes the conversion of power supply AC signal through simple signal rectification and merging, coupled transmission and charging and discharging process, without the need for additional design of virtual reference points or other processing, thereby simplifying the phase loss detection of three-phase AC power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A schematic diagram of a three-phase AC input power phase loss detection circuit structure provided by an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of a three-phase AC input power phase loss detection circuit provided by an embodiment of the present invention;

[0054] Figure 3 A schematic diagram of a three-phase AC input power phase loss detection system provided by an embodiment of the present invention;

[0055] Figure 4 A schematic diagram of a three-phase AC input power phase loss detection simulation circuit provided by an embodiment of the present invention;

[0056] Figure 5 A schematic diagram of the waveforms of the rectified voltage and the detected voltage when there is no phase in a three-phase AC input power supply provided by an embodiment of the present invention;

[0057] Figure 6 A schematic diagram of the waveforms of the rectified voltage and the detected voltage when a three-phase AC input power supply is missing a phase provided by an embodiment of the present invention;

[0058] Figure 7 A schematic diagram of a simulation waveform when a three-phase AC input power source has no phase after parameter adjustment provided by an embodiment of the present invention;

[0059] Figure 8 A schematic diagram of a simulation waveform when a three-phase AC input power supply is missing a phase after parameter adjustment provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Embodiment 1:

[0062] This embodiment provides a three-phase AC input power phase loss detection circuit. Figure 1 As shown, it includes: a rectifier module, a coupling module and a charge and discharge module; wherein:

[0063] The rectifier module includes an input terminal for electrically connecting to a three-phase AC power source to rectify and combine the three-phase AC signals of the three-phase AC power source into a combined rectified signal;

[0064] The rectifier module is electrically connected to the first input terminal of the coupling module through the positive output terminal, and is electrically connected to the second input terminal of the coupling module through the negative input terminal. The first output terminal of the coupling module is electrically connected to the positive input terminal of the charge-discharge module, and the second output terminal is electrically connected to the negative input terminal of the charge-discharge module, so as to couple and transmit the combined rectifier signal to the charge-discharge module through the coupling module to obtain a charge-discharge signal.

[0065] The charge and discharge module contains a voltage detection interface. The charge and discharge module performs charging and discharging processes under the charge and discharge signals to generate a detection voltage, thereby obtaining the detection voltage through the voltage detection interface, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0066] In the specific implementation process, through simple circuit rectification, coupling, charging and discharging, there is no need to design a virtual N-line reference point additionally, and the three-phase AC power output is rectified into one signal to realize the phase loss detection of the three-phase AC circuit, thereby reducing the cost of components and avoiding the detection circuit from being too large, thereby simplifying the design of the three-phase AC input power phase loss detection circuit.

[0067] Optionally, the rectifier module includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; wherein:

[0068] The anode of the first diode serves as the first input end of the rectifier module and is electrically connected to the first input end of the three-phase AC input power supply. The anode of the first diode is electrically connected to the cathode of the fourth diode.

[0069] The anode of the second diode serves as the second input end of the rectifier module and is electrically connected to the second input end of the three-phase AC input power supply. The anode of the second diode is electrically connected to the cathode of the fifth diode.

[0070] The anode of the third diode serves as the third input terminal of the rectifier module and is electrically connected to the third input terminal of the three-phase AC input power supply. The anode of the third diode is electrically connected to the cathode of the sixth diode.

[0071] The cathode of the first diode is electrically connected to the cathode of the second diode, the cathode of the second diode is electrically connected to the cathode of the third diode, and the cathode of the third diode serves as a positive output end of the rectifier module and is electrically connected to the first input end of the coupling module;

[0072] The anode of the fourth diode is electrically connected to the anode of the fifth diode, the anode of the fifth diode is electrically connected to the anode of the sixth diode, and the anode of the sixth diode serves as the negative output end of the rectifier module and is electrically connected to the second input end of the coupling module.

[0073] In the specific implementation process, six diodes are used to form a rectifier circuit, and they are connected to the power supply to be detected through different interfaces, so that the rectifier module receives the AC signal of each phase of the three-phase AC input power supply and rectifies it into a signal, providing a signal basis for the charge and discharge module to detect, and there is no need to detect three paths separately, which simplifies the detection circuit. When the three-phase AC input power supply is not missing a phase, the voltage of the three-phase AC voltage after passing through the rectifier circuit in the rectifier module is a DC voltage with a small amount of AC component; when the three-phase AC input power supply is missing a phase, the three-phase AC voltage is a rectified sine wave after passing through the rectifier circuit.

[0074] Optionally, the coupling module includes an optical coupler, and the optical coupler includes a first input end, a second input end, a first output end, and a second output end; wherein:

[0075] The first input end of the optical coupler serves as the first input end of the coupling module and is electrically connected to the positive output end of the rectifier module;

[0076] The second input end of the optical coupler serves as the second input end of the coupling module and is electrically connected to the negative output end of the rectifier module;

[0077] The first output end of the optical coupler serves as the first output end of the coupling module and is electrically connected to the positive input end of the charge and discharge module;

[0078] The second output end of the optical coupler serves as the second output end of the coupling module and is electrically connected to the negative input end of the charge and discharge module.

[0079] In the specific implementation process, the coupling module realizes signal transmission through the optical coupler to provide signals for the charging and discharging module.

[0080] Optionally, the coupling module also includes: a current limiting resistor, wherein: a first end of the current limiting resistor is electrically connected to the positive output end of the rectifier module, and a second end of the current limiting resistor is electrically connected to the first input end of the optocoupler, so as to scale the combined rectified signal, so that the optocoupler is in a preset working state, and generates the required charging and discharging signals.

[0081] In the specific implementation process, the coupling module adjusts the combined rectified signal through the current limiting resistor to put the optical coupler in the best working state and lays the foundation for a simpler and more intuitive detection and analysis method for phase loss detection.

[0082] Optionally, the charge and discharge module includes: a DC resistor, a seventh diode, a charge and discharge resistor and a detection capacitor; wherein:

[0083] The first end of the DC resistor is electrically connected to the anode of the seventh diode, and the second end of the DC resistor is electrically connected to the second end of the detection capacitor;

[0084] The cathode of the seventh diode is electrically connected to the first end of the charge and discharge resistor;

[0085] The first end of the charge-discharge resistor is electrically connected to the first end of the detection capacitor, and the second end of the charge-discharge resistor is electrically connected to the second end of the detection capacitor;

[0086] The anode of the seventh diode is used as the positive input terminal of the charge-discharge module and is electrically connected to the first output terminal of the coupling module;

[0087] The second end of the charge-discharge resistor is used as a charge-discharge negative input end and is electrically connected to the second output end of the coupling module;

[0088] The two ends of the detection capacitor are used as voltage detection interfaces.

[0089] During the specific implementation process, a charge and discharge circuit is designed through a DC resistor, a seventh diode, a charge and discharge capacitor and a detection capacitor, so that the charge and discharge module performs the charging and discharging process in a preset manner under the action of the charge and discharge signal, thereby performing phase loss detection based on the detection voltage generated at both ends of the detection capacitor, and the analysis of the detection results is simple and intuitive.

[0090] In the specific implementation process, the phase loss detection circuit obtained by the above scheme is as follows Figure 2 As shown, D1-D6 represent the diodes that make up the rectifier module, U1 represents the optical coupler in the coupling module, R1 represents the current limiting resistor, R2 represents the DC resistor, D7 represents the seventh diode, R3 represents the charge and discharge resistor, and C1 represents the detection capacitor. VCC is used for low-voltage power supply, wherein the second end of the DC resistor is electrically connected to the positive electrode of VCC, the second end of the detection capacitor is electrically connected to the negative electrode of VCC, and is grounded. That is, D1-D6 constitutes a three-phase rectifier circuit; R1 is a current limiting resistor; U1 is an optical coupler; R2, D7, R3, and C1 constitute a charge and discharge circuit; the detection circuit determines whether the three-phase input power supply has a phase loss by detecting the voltage across the capacitor C1. When the three-phase input power supply is not phase-lost, the voltage across C1 is approximately equal to 0V; when the three-phase input power supply is phase-lost, the voltage across C1 increases, and the specific voltage value depends on the circuit parameters.

[0091] This embodiment designs the rectifier module, the coupling module and the charge and discharge module separately, and finally obtains a phase loss detection circuit with simple circuits and convenient and intuitive detection and analysis, which reduces the cost of components and avoids the detection circuit from being too large.

[0092] Embodiment 2:

[0093] This embodiment provides a three-phase AC input power phase loss detection system. Figure 3 As shown, it includes a three-phase AC input power phase loss detection circuit, a detection power supply unit and a result detection unit, wherein:

[0094] The detection power supply unit includes a three-phase AC input power supply required for detection, and is used to provide a three-phase AC signal for the phase loss detection circuit;

[0095] The phase loss detection circuit is used to rectify and merge the three-phase AC signal into a combined rectified signal through the rectifier module, and couple the combined rectified signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, so that the charge and discharge module performs a charging and discharging process under the charge and discharge signal to generate a detection voltage;

[0096] The result detection unit is used to obtain the detection voltage in real time, and perform phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0097] In the specific implementation process, the phase loss detection system provided in this embodiment performs simple power signal rectification, coupling, charging and discharging through the phase loss detection circuit to realize the phase loss detection of the power supply, providing a system with a simple and convenient structure for phase loss detection.

[0098] Optionally, the phase loss detection circuit also includes: rectifying and combining the three-phase AC signals into a combined rectified signal through a rectifier module, and limiting the current based on the combined rectified signal to obtain a coupling signal, so as to couple the coupling signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, so that the charge and discharge module performs a charging and discharging process under the charge and discharge signal to generate a detection voltage.

[0099] In the specific implementation process, in the above scheme, the combined rectified signal is further processed so that the phase loss detection circuit is in a preset working state, so that the generated detection voltage result is more accurate and intuitive.

[0100] In the specific implementation process, the phase loss detection circuit simulation in the system is as follows Figure 4 As shown, the power supply voltage is 3.3V at this time. After the three-phase AC voltage passes through the rectifier circuit composed of D1-D6, the voltage is represented by Vrec:

[0101] (1) When the three-phase AC input power supply is not missing a phase, the voltage after the three-phase AC voltage passes through the rectifier circuit composed of D1-D6 is represented by Vrec, which is a DC voltage with a small AC component. It is applied to R1 and the photodiode of U1. The current of the photodiode is IF, and its magnitude is IF = (Vrec-Vf) / R1, and Vf is the voltage drop of the photodiode. At this time, the current IC of the phototransistor of U1 is CTR*IF, where CTR is the current transfer ratio of the optocoupler. The current IC is provided by the DC power supply VCC through the resistor R2, and the voltage drop on the resistor R2 is V2 = VCC-Vce, where Vce is the voltage across the phototransistor of U1. At this time, the phototransistor needs to work in a saturated state, so the value of R2 needs to be greater than (VCC-Vcesat)*IC, where Vcesat is the saturated operating voltage of the phototransistor. At this time, the voltage across the capacitor C1 is Vcesat minus the voltage drop of the diode D7, which is approximately equal to 0V.

[0102] (2) When the three-phase AC input power is missing a phase, the three-phase AC input power is a rectified sine wave after passing through the rectifier circuit composed of D1-D6, which is applied to both ends of the photodiode of R1 and U1. The current of the photodiode is IF, and its magnitude is IF = (Vrec-Vf) / R1. The magnitude of IF gradually decreases as Vrec decreases. When Vrec drops below Vf, the value of current IF is equal to 0A. The current of U1 phototransistor is IC = CTR*IF, and the magnitude of IC also changes with the voltage Vrec. When Vrec decreases from the maximum value to 0V, the value of IC also gradually decreases from a certain maximum value to zero. When IC gradually decreases, the phototransistor will exit saturation operation. state, at this time Vce will gradually increase, and start to charge C1 and R3 through D7, and its charging current is equal to (VCC-Vce) / R1-IC; and when Vrec gradually increases, IC starts to increase, Vce gradually decreases, and the phototransistor will enter the saturated working state again. When Vce gradually decreases to the point where D7 is turned off, C1 will discharge through R3, and the discharge current is VC1 / R3; the voltage of capacitor C1 will repeat the above charging and discharging process as the voltage Vrec changes periodically, and gradually increase until the charging and discharging reaches a balance; at this time, in order to make the VC1 value gradually increase and quickly reach a balanced state, the charging current needs to be greater than the discharging current, so the value of resistor R3 needs to be much larger than the value of resistor R2;

[0103] Based on the above analysis, when the three-phase AC input power supply is missing a phase, the voltage across C1 will increase. The voltage across capacitor C1 can be detected to determine whether the three-phase AC input power supply is missing a phase.

[0104] Optionally, the phase loss detection system also includes: a result verification unit, which is used to adjust the coupling transmission parameters in the phase loss detection circuit according to a preset adjustment method, so that the phase loss detection circuit generates a new detection voltage based on the three-phase AC signal, so that the result detection unit performs phase loss detection based on the new detection voltage and a preset normal range to obtain a new phase loss detection result, so as to complete the result verification based on the phase loss detection result and the new phase loss detection result and obtain the final phase loss detection result.

[0105] In the specific implementation process, by adjusting parameters and re-verifying, the problem of large errors in detection results caused by environmental factors in actual applications was solved, and the robustness and reliability of the system were enhanced.

[0106] In the specific implementation process, the measured three-phase AC input power phase voltage is 100VAC / 50Hz, the value of R1 is 50k, the voltage drop of the optocoupler photodiode is 1.1V, the current transfer ratio CTR is 0.2, the saturation voltage is 0.15V, the value of resistor R2 is 5k, the value of resistor R3 is 511k, and the value of capacitor C1 is 0.47u. When the three-phase AC input source has no missing phase, the rectified voltage and the detection voltage simulation waveform are as follows Figure 5 As shown, VC1 is approximately equal to 50mv; when the three-phase AC input source has no missing phase, the rectified voltage and detection voltage simulation waveforms are as follows Figure 6 As shown in the figure, VC1 is approximately equal to 2.7v, so the voltage of VC1 can be used to detect whether the three-phase AC input source is missing a phase. However, in actual applications, the transmission ratio CTR of the optocoupler will change with temperature. In order to verify the robustness and reliability of the circuit, the transmission ratio CTR of the optocoupler is increased by 3 times and re-verified; when the three-phase AC input source is not missing a phase, the simulation waveform is as follows Figure 7 , VC1 is approximately equal to 50mv; when the three-phase AC input source has no missing phase, the simulation waveform is as follows Figure 8 , VC1 is approximately equal to 2.4V; therefore, the phase loss detection circuit has good reliability and robustness, and can determine that the three-phase AC input is phase-lost when the value of VC1 is greater than 1.5V.

[0107] The system structure proposed in this embodiment is simple and easy to implement. The phase loss detection circuit does not require an N-line reference and is applicable to both three-phase three-wire AC input power and three-phase four-wire AC input power. The circuit is simple, requiring only a three-phase rectifier bridge, three resistors, a capacitor, an optocoupler, and a diode. The power supply is simple, requiring only a low-voltage VCC power supply, which can be shared with the control circuit in the system (such as the 3.3V power supply of the MCU), without the need for negative voltage or DC flat-type power supply. The phase loss detection circuit is used to perform signal conversion processing to obtain detection data, and the circuit parameters are adjusted according to actual conditions during application to enhance the robustness and reliability of the detection circuit, make the system more reliable, and improve detection accuracy.

[0108] Embodiment three:

[0109] This embodiment provides a three-phase AC input power phase loss detection method, which is applied to a three-phase AC input power phase loss detection system, including the following steps:

[0110] Performing rectification and merging based on three-phase AC signals of a three-phase AC power supply to obtain a combined rectified signal;

[0111] Based on the combined rectified signal, coupled transmission is performed to obtain the charging and discharging signal;

[0112] The charging and discharging process is performed based on the charge and discharge signal to generate a detection voltage, thereby obtaining the detection voltage in real time, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

[0113] The above scheme realizes the conversion of power supply AC signal through rectification and merging, coupled transmission and charging and discharging process, thereby realizing phase loss detection.

[0114] Optionally, coupling transmission is performed based on the combined rectified signal to obtain the charge and discharge signal, including: current limiting based on the combined rectified signal to obtain the coupling signal, and obtaining the charge and discharge signal based on the coupling signal.

[0115] The phase loss detection method provided in this embodiment realizes the conversion of power supply AC signals through simple signal rectification and merging, coupled transmission and charging and discharging processes, without the need for additional design of virtual reference points or other processing, thereby simplifying the phase loss detection of three-phase AC power supply.

[0116] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A three-phase AC input power supply phase loss detection circuit, characterized in that: include: Rectification module, coupling module and charging and discharging module; wherein: The rectifier module includes an input terminal for electrically connecting to a three-phase AC power source to rectify and combine the three-phase AC signals of the three-phase AC power source into a combined rectified signal; The rectifier module is electrically connected to the first input terminal of the coupling module through the positive output terminal, and is electrically connected to the second input terminal of the coupling module through the negative input terminal. The first output terminal of the coupling module is electrically connected to the positive input terminal of the charge-discharge module, and the second output terminal is electrically connected to the negative input terminal of the charge-discharge module, so as to couple and transmit the combined rectifier signal to the charge-discharge module through the coupling module to obtain a charge-discharge signal. The charge and discharge module contains a voltage detection interface. The charge and discharge module performs charging and discharging processes under the charge and discharge signal to generate a detection voltage, thereby obtaining the detection voltage through the voltage detection interface, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

2. A three-phase AC input power supply phase loss detection circuit according to claim 1, characterized in that: The rectifier module comprises: a first diode, a second diode, a third diode, a fourth diode, a fifth diode and a sixth diode; wherein: The anode of the first diode serves as the first input end of the rectifier module and is electrically connected to the first input end of the three-phase AC input power supply, and the anode of the first diode is electrically connected to the cathode of the fourth diode; The anode of the second diode serves as the second input end of the rectifier module and is electrically connected to the second input end of the three-phase AC input power supply, and the anode of the second diode is electrically connected to the cathode of the fifth diode; The anode of the third diode serves as the third input terminal of the rectifier module and is electrically connected to the third input terminal of the three-phase AC input power supply. The anode of the third diode is electrically connected to the cathode of the sixth diode. The cathode of the first diode is electrically connected to the cathode of the second diode, the cathode of the second diode is electrically connected to the cathode of the third diode, and the cathode of the third diode serves as a positive output end of the rectifier module and is electrically connected to the first input end of the coupling module; The anode of the fourth diode is electrically connected to the anode of the fifth diode, the anode of the fifth diode is electrically connected to the anode of the sixth diode, and the anode of the sixth diode serves as a negative output end of the rectifier module and is electrically connected to the second input end of the coupling module.

3. A three-phase AC input power supply phase loss detection circuit according to claim 1, characterized in that: The coupling module comprises: an optical coupler, wherein the optical coupler comprises a first input end, a second input end, a first output end, and a second output end; wherein: The first input end of the optical coupler serves as the first input end of the coupling module and is electrically connected to the positive output end of the rectifier module; The second input end of the optical coupler serves as the second input end of the coupling module and is electrically connected to the negative output end of the rectifier module; The first output end of the optical coupler serves as the first output end of the coupling module and is electrically connected to the positive input end of the charge and discharge module; The second output end of the optical coupler serves as the second output end of the coupling module and is electrically connected to the negative input end of the charge and discharge module.

4. A three-phase AC input power supply phase loss detection circuit according to claim 3, characterized in that: The coupling module also includes: a current limiting resistor, wherein: a first end of the current limiting resistor is electrically connected to the positive output end of the rectifier module, and a second end of the current limiting resistor is electrically connected to the first input end of the optical coupler, so as to scale the combined rectified signal, put the optical coupler in a preset working state, and generate the required charging and discharging signals.

5. A three-phase AC input power supply phase loss detection circuit according to claim 1, characterized in that: The charging and discharging module includes: a DC resistor, a seventh diode, a charging and discharging resistor and a detection capacitor; wherein: The first end of the DC resistor is electrically connected to the anode of the seventh diode, and the second end of the DC resistor is electrically connected to the second end of the detection capacitor; The cathode of the seventh diode is electrically connected to the first end of the charge and discharge resistor; The first end of the charge-discharge resistor is electrically connected to the first end of the detection capacitor, and the second end of the charge-discharge resistor is electrically connected to the second end of the detection capacitor; The anode of the seventh diode is used as the positive input terminal of the charge-discharge module and electrically connected to the first output terminal of the coupling module; The second end of the charge-discharge resistor is used as a charge-discharge negative input end and is electrically connected to the second output end of the coupling module; The two ends of the detection capacitor are used as the voltage detection interface.

6. A three-phase AC input power phase loss detection system, characterized in that: The invention comprises a three-phase AC input power supply phase loss detection circuit, a detection power supply unit and a result detection unit as claimed in any one of claims 1 to 5, wherein: The detection power supply unit includes a three-phase AC input power supply required for detection, and is used to provide a three-phase AC signal for the phase loss detection circuit; The phase loss detection circuit is used to rectify and merge the three-phase AC signal into a combined rectified signal through the rectifier module, and couple the combined rectified signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, so that the charge and discharge module performs a charging and discharging process under the charge and discharge signal to generate a detection voltage; The result detection unit is used to obtain the detection voltage in real time, and perform phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

7. A three-phase AC input power supply phase loss detection system according to claim 6, characterized in that: The phase loss detection circuit also includes: a device for rectifying and merging the three-phase AC signals into a combined rectified signal through a rectifier module, and performing current limiting based on the combined rectified signal to obtain a coupling signal, so as to couple and transmit the coupling signal to the charge and discharge module through the coupling module to obtain a charge and discharge signal, so that the charge and discharge module performs a charging and discharging process under the charge and discharge signal to generate a detection voltage.

8. A three-phase AC input power supply phase loss detection system according to claim 6, characterized in that: It also includes: a result verification unit, which is used to adjust the coupling transmission parameters in the phase loss detection circuit according to a preset adjustment method, so that the phase loss detection circuit generates a new detection voltage based on the three-phase AC signal, so that the result detection unit performs phase loss detection based on the new detection voltage and the preset normal range to obtain a new phase loss detection result, so as to complete the result verification based on the phase loss detection result and the new phase loss detection result and obtain the final phase loss detection result.

9. A three-phase AC input power supply phase loss detection method, using a three-phase AC input power supply phase loss detection system as claimed in any one of claims 6 to 8, characterized in that: The following steps are involved: Performing rectification and merging based on three-phase AC signals of a three-phase AC power supply to obtain a combined rectified signal; Based on the combined rectified signal, coupled transmission is performed to obtain the charging and discharging signal; The charging and discharging process is performed based on the charge and discharge signal to generate a detection voltage, thereby obtaining the detection voltage in real time, and performing phase loss detection based on the detection voltage and a preset normal range to obtain a phase loss detection result.

10. A three-phase AC input power supply phase loss detection method according to claim 9, characterized in that: The method of performing coupling transmission based on the combined rectified signal to obtain the charge and discharge signal includes: performing current limiting based on the combined rectified signal to obtain the coupling signal, and obtaining the charge and discharge signal based on the coupling signal.

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