Three-phase phase sequence detection circuit, method and system

Abstract

The invention discloses a three-phase phase sequence detection circuit, method and system, and relates to the field of phase sequence detection.The circuit is connected between any phase line and a zero line of a three-phase power supply and comprises a voltage limiting module, a protection module, an optical coupling isolator and a signal output module; one end of the voltage limiting module is connected with any phase line of the three-phase power supply; the input end of the protection module is connected with the other end of the voltage limiting module; the first end of the optical coupling isolator is connected with the output end of the protection module, the second end of the optical coupling isolator is connected with the signal output module, accurate pre-detection of the three-phase phase sequence is achieved through the circuit, and the risk of equipment damage is avoided.

Description

Technical Field

[0001] This invention relates to the field of phase sequence detection, and in particular to a three-phase phase sequence detection circuit, method and system. Background Technology

[0002] The correctness of the phase sequence of a three-phase power supply directly affects the safe operation of industrial electrical equipment. After the three-phase equipment is transported to the site and connected to a three-phase power supply, the phase sequence of the input power supply should, in principle, be the same as that during the production and commissioning phase. Otherwise, differences in phase sequence may cause overcurrent in the circuit, equipment failure, or even equipment burnout.

[0003] Traditional methods typically rely on brief power-on testing to determine phase sequence, but this method carries high operational risks and poses significant safety hazards to mechanical equipment that cannot tolerate malfunctions, failing to meet the high reliability and safety requirements of industrial equipment.

[0004] Therefore, how to achieve secure sequencing and improve equipment debugging efficiency has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a three-phase sequence detection circuit, method, and system to solve the problem of how to achieve phase sequence identification by connecting a microcontroller through current-limiting resistors and optocoupler isolation, thereby avoiding the potential risks caused by trial and error in phase sequence circuits.

[0006] To solve the above-mentioned technical problems, embodiments of the present invention provide a three-phase phase sequence detection circuit, which is connected between any phase line and the neutral line of a three-phase power supply, including: a voltage limiting module, a protection module, an optocoupler isolator, and a signal output module; One end of the voltage limiting module is connected to any phase line of a three-phase power supply; The input terminal of the protection module is connected to the other end of the voltage limiting module; The first end of the optocoupler is connected to the output end of the protection module, and the second end of the optocoupler is connected to the signal output module.

[0007] Furthermore, the voltage limiting module is composed of several voltage limiting resistors connected in series.

[0008] Furthermore, the protection module consists of diodes.

[0009] Furthermore, the circuit also includes resistor-capacitor components connected in parallel between the output terminal of the protection module and the first terminal of the optocoupler isolator.

[0010] Furthermore, the signal output module includes a transistor and a filter capacitor connected in parallel with the transistor.

[0011] Furthermore, the transistor is an NPN transistor.

[0012] Furthermore, the number of voltage-limiting resistors is five.

[0013] Another embodiment of the present invention provides a three-phase sequence detection method, characterized in that it includes: The original voltage signal provided by the three-phase power supply is converted into three square wave pulse signals; Within a preset acquisition period, the timing of the transition edges of each of the square wave pulse signals is captured; The phase sequence detection result of the three-phase power supply is determined based on the timing of the transition edges.

[0014] Another embodiment of the present invention provides a three-phase sequence detection system for performing the above-described three-phase sequence detection method, comprising: a processor and three sets of the three-phase sequence detection circuits connected to the processor.

[0015] Furthermore, the processor is a microcontroller.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following: This invention comprises a phase sequence detection circuit consisting of an optocoupler isolator, a voltage limiting module, a protection module, and an output module connected in sequence. The integrated optocoupler isolator significantly improves the safety and signal anti-interference capability of non-invasive phase sequence detection. Connecting the voltage limiting module directly in series with the phase line effectively protects the optocoupler. Connecting the protection module in series in the circuit effectively prevents high voltage from damaging the optocoupler, improving the durability of the detection circuit. Furthermore, the signal output module reduces signal detection delay, providing accurate data support for subsequent judgment. The collaborative action of multiple modules enables accurate pre-detection of the three-phase sequence without starting the load, avoiding the risk of equipment damage. Attached Figure Description

[0017] Figure 1 This is a block diagram of the overall structure of a three-phase sequence detection circuit in one embodiment of the present invention; Figure 2 This is a set of phase sequence detection circuit diagrams in one embodiment of the present invention; Figure 3 This is a circuit diagram of a three-phase phase sequence detection circuit applied to a three-phase power supply in one embodiment of the present invention; Figure 4 This is a normal waveform diagram of the three-phase input provided by the present invention; Figure 5 It is the square wave pulse signal of phases A and B of the three-phase power supply provided by this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] One embodiment of the present invention provides a three-phase phase sequence detection circuit. For details, please refer to [link to specific documentation]. Figure 1 , Figure 1 The diagram shown illustrates a three-phase sequence detection circuit structure according to one embodiment of the present invention, comprising the following steps: The detection circuit is located between the phase lines and the neutral line of the three-phase power supply. In some embodiments of the present invention, the three phase lines of the three-phase power supply (phase A, phase B, and phase C) are all connected to a detection circuit. In this embodiment, taking a detection circuit as an example, it includes a voltage limiting module 1, a protection module 2, an optocoupler isolator 3, and a signal output module 4.

[0023] The voltage limiting module 1 consists of several voltage limiting resistors connected in series. One end of the module is connected to any phase of the three-phase power supply, and the other end is connected to the input terminal of the protection module 2. It is used to reduce the AC voltage and limit the current supplied by the three-phase power supply. In this embodiment, preferably, the number and resistance value of the voltage limiting resistors connected in series are configured such that, under the highest operating voltage of the circuit, the actual power consumption of each resistor is less than 70% of its rated power consumption, and its actual withstand voltage is less than 50% of its rated withstand voltage. Based on this, five 1206 packaged voltage limiting resistors can preferably be connected in series. For details, please refer to... Figure 2 A set of detection circuit diagrams is shown. It can be seen that the voltage limiting module 1 is composed of voltage limiting resistors R70, R120, R123, R72 and R73 connected in series. During the three-phase sequencing process, one end of R70 serves as the input terminal of the voltage limiting module 1 and is connected to one phase of the three-phase power supply.

[0024] Understandably, the power consumption of each voltage-limiting resistor is calculated based on the maximum allowable operating voltage (i.e., the rated voltage AC 264V between the three-phase input phase line and the neutral line of the low-voltage power supply grid). Taking five voltage-limiting resistors as an example (each voltage-limiting resistor has a design value of 16KΩ and a rated power consumption of 250mW), under extreme operating conditions, if their total power consumption Pw = 856.7mW is calculated, then the power consumption allocated to each current-limiting resistor is 171mW, which is 68.4% < 70%. Under normal voltage conditions, this proportion will be even lower than 70%. This means that the voltage-limiting module designed in this embodiment will not be damaged due to overheating, leaving a large safety margin.

[0025] For voltage withstand capability, for example, at the rated voltage AC 264V, the voltage allocated to each voltage-limiting resistor must also be lower than the peak voltage, where [(AC264V - diode voltage drop) × 1.414] / number of resistors = peak voltage.

[0026] In this embodiment, a diode is used as the circuit protection module 2, such as... Figure 2 As shown, the preferred diode is model M7, with a reverse withstand voltage of 1000V and a forward conduction current of 1A. It protects the entire circuit by reversing the high voltage coming from the neutral line.

[0027] In this circuit, the output terminal of protection module 2 is connected to the first terminal of optocoupler isolator 3. To further ensure reliable circuit operation, a resistor-capacitor (RC) element is connected in parallel between the output terminal of protection module 2 and the first terminal of optocoupler isolator 3 for interference suppression. Specifically, the parallel capacitor and resistor elements eliminate some noise in the circuit, accelerate the optocoupler's shutdown speed, and protect the optocoupler using the reverse cutoff voltage of the diode when the AC voltage reverses. It should be understood that in this embodiment, the first terminal of optocoupler isolator 3 refers to the input terminal of its built-in diode, and the second terminal is the output terminal of its built-in transistor.

[0028] Furthermore, the second terminal of the optocoupler 3 is connected to the signal output module 4, wherein the signal output module 4 includes a transistor and a filter capacitor connected in parallel with the transistor. Preferably, the transistor is an NPN transistor, such as... Figure 2 The NPN transistor T20 and filter capacitor C12 shown can reduce the delay time of the rising and falling edges of the output waveform, thereby improving the waveform fidelity.

[0029] It should be understood that the output terminal of signal output module 4 is connected to the processor, thereby enabling the detection of phase sequence.

[0030] In summary, this circuit design is used to connect between any phase line and neutral line of a three-phase power supply. Following the signal flow direction, it includes: a voltage limiting module, a protection module, an optocoupler isolator, and a signal output module. The first end of the voltage limiting module is connected to the phase line, and its second end is connected to the input terminal of the protection module. The output terminal of the protection module is connected to the first terminal of the optocoupler isolator. The second terminal of the optocoupler isolator is finally connected to the signal output module. This circuit structure together constitutes a circuit that draws power from the high-voltage side, performs electrical isolation and signal shaping, and finally outputs a square wave signal that can be recognized by the processor, improving the efficiency and accuracy of non-invasive three-phase phase sequence measurement.

[0031] An embodiment of the present invention also provides a three-phase sequence detection system, which includes: a processor and three sets of three-phase sequence detection circuits connected to the processor. The processor may be a microcontroller with a built-in timer. In this embodiment, the microcontroller is provided with signal input interfaces that are respectively connected to the input terminals of the three sets of detection circuits, which can realize the phase sequence determination of the voltage signals output by the A, B, and C phases of the three-phase power supply.

[0032] Based on this, an embodiment of the present invention provides a three-phase sequence detection method, which specifically includes the following steps: S1. Convert the original voltage signal provided by the three-phase power supply into three square wave pulse signals.

[0033] S2. Within the preset acquisition period, capture the timing of the transition edges of each square wave pulse signal.

[0034] S3. Determine the phase sequence detection result of the three-phase power supply based on the timing of the transition edges.

[0035] It should be understood that when the phase sequence of the three-phase power supply is correct, the phase difference between the current and voltage signals should be 120 degrees, while when the phase sequence is incorrect, the phase difference will deviate from 120 degrees.

[0036] For an example, please refer to the three-phase detection circuit diagram applied to a three-phase power supply. Figure 3 As shown, after the three-phase detection circuit converts the original AC voltage signal provided by the three-phase power supply, the processor collects three square wave pulse signals at a specific period, and then calculates the timing of the transition edges of these three square wave pulse signals, that is, the time difference between the rising edge or the falling edge of the pulse.

[0037] Specifically, when the three-phase input is normal, the phase waveforms of the three-phase input are shown below. Figure 4 As shown, the power cycle can be divided into 6 equal parts, namely T1, T2, T3, T4, T5, and T6. The time difference between phase A and phase B at the same point in time can be calculated, expressed as: Similarly, the time difference between phase B and phase C was calculated to be 6.66 ms.

[0038] For example, the microcontroller's timer is configured to have a 1ms acquisition period. During this period, the microcontroller receives three square wave pulse signals from the receiving circuit, records the rising or falling edges of these signals, and then calculates the time differences between phases A and B, and between phases B and C. If the time differences are all close to 6.66ms, the phase sequence is correct; otherwise, the phase sequence is incorrect. Taking phases A and B of a three-phase power supply as an example, the square wave pulse signals acquired by the microcontroller are as follows: Figure 5 As shown, the oscilloscope displays the square wave waveforms of phase A (blue line) and phase B (yellow line). It can be seen that the rising edge of phase B is delayed by about 6.66ms compared to the rising edge of phase A.

[0039] By analyzing the timing of the transition edges of the remaining phases in the same manner, it can be determined whether the phase sequence of the current three-phase power supply is correct. It should be understood that during the sequencing process in this embodiment, the load of the three-phase power supply does not need to be started, and it can be determined in a very short time whether the phase sequence of the three-phase input lines is consistent with the factory setting.

[0040] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A three-phase phase sequence detection circuit, characterized in that, Connected between any phase line and the neutral line of a three-phase power supply, including: a voltage limiting module, a protection module, an optocoupler isolator, and a signal output module; One end of the voltage limiting module is connected to any phase line of a three-phase power supply; The input terminal of the protection module is connected to the other end of the voltage limiting module; The first end of the optocoupler is connected to the output end of the protection module, and the second end of the optocoupler is connected to the signal output module.

2. The three-phase sequence detection circuit as described in claim 1, characterized in that, The voltage limiting module is composed of several voltage limiting resistors connected in series.

3. The three-phase sequence detection circuit as described in claim 1, characterized in that, The protection module consists of diodes.

4. The three-phase sequence detection circuit as described in claim 1, characterized in that, The circuit also includes resistor-capacitor components connected in parallel between the output terminal of the protection module and the first terminal of the optocoupler isolator.

5. The three-phase sequence detection circuit as described in claim 1, characterized in that, The signal output module includes a transistor and a filter capacitor connected in parallel with the transistor.

6. The three-phase sequence detection circuit as described in claim 5, characterized in that, The transistor is an NPN type transistor.

7. The three-phase sequence detection circuit as described in claim 2, characterized in that, The number of voltage-limiting resistors is five.

8. A three-phase sequence detection method, characterized in that, include: The original voltage signal provided by the three-phase power supply is converted into three square wave pulse signals; Within a preset acquisition period, the timing of the transition edges of each of the square wave pulse signals is captured; The phase sequence detection result of the three-phase power supply is determined based on the timing of the transition edges.

9. A three-phase sequence detection system, characterized in that, The method for performing the three-phase sequence detection method as described in claim 8 includes: a processor and three sets of three-phase sequence detection circuits as described in any one of claims 1 to 7 connected to the processor.

10. The three-phase sequence detection system as described in claim 9, characterized in that, The processor is a microcontroller.

Images