A phase sequence detection circuit without external power supply

Abstract

A phase sequence detection circuit without external power supply, three input ports of three-phase alternating current power supply are connected with input ends of two optocoupler relays respectively, two detection channels are formed between the three input ports, and then output channels outputting phase sequence detection signals to external circuits are formed through output ends of the two optocoupler relays, when three-phase phase sequence is normal, input ends of the two optocoupler relays are turned on at the same time, so that output ends of the two optocoupler relays are turned on at the same time, and phase sequence detection signals can be output to external circuits, when three-phase phase sequence is abnormal, input ends of the two optocoupler relays cannot be turned on at the same time, so that output ends of the two optocoupler relays cannot be turned on at the same time, and phase sequence detection signals cannot be output to external circuits at this time, whether three-phase phase sequence of three-phase alternating current power supply exists abnormality can be judged through whether phase sequence detection signals can be output, and three-phase alternating current power supply electric signals no longer need to be received and processed by an additional power supply intelligent chip.

Description

Technical Field

[0001] This invention relates to the field of phase sequence detection, and more particularly to a phase sequence detection circuit that does not require an external power supply. Background Technology

[0002] A three-phase AC power supply consists of three AC potentials with the same frequency, equal amplitude, and phases differing by 120° sequentially. Under normal operating conditions, the three-phase input phase sequence of a three-phase AC power supply must be correct. Therefore, it is necessary to detect the input three-phase phase sequence to promptly identify any abnormalities. Existing phase sequence detection circuits receive the electrical signals from the three-phase AC power supply using a smart chip, then process the signals to determine if the three-phase sequence is normal. This detection method requires an external power supply to the smart chip, leading to a complex circuit structure, reduced reliability, and higher cost for the smart chip. Furthermore, the smart chip may misjudge during operation, making it impractical. Summary of the Invention

[0003] To address the problem that existing phase sequence detection circuits rely on externally powered smart chips, this invention provides a phase sequence detection circuit that does not require an external power supply.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a phase sequence detection circuit that does not require external power supply, comprising two optocoupler relays; the input port A of the three-phase AC power supply is connected to the positive input terminal a of the first optocoupler relay, and the input port B of the three-phase AC power supply is connected to the negative input terminal b of the first optocoupler relay, forming an AB detection path between input port A and input port B; the input port B of the three-phase AC power supply is also connected to the positive input terminal a of the second optocoupler relay, and the input port C of the three-phase AC power supply is connected to the negative input terminal b of the second optocoupler relay, forming a BC detection path between input port B and input port C; an AB current limiting component, an AB rectification component, and an AB filtering component are connected to the AB detection path, and a BC current limiting component, a BC rectification component, and a BC filtering component are connected to the BC detection path;

[0005] The positive output terminal c of the first optocoupler relay can output a positive electrical signal to an external circuit, and the negative output terminal d of the second optocoupler relay can output a negative electrical signal to an external circuit. The negative output terminal d of the first optocoupler relay and the positive output terminal c of the second optocoupler relay are connected to each other. When the positive input terminal a and the negative input terminal b of the first optocoupler relay are energized, the positive output terminal c and the negative output terminal d of the first optocoupler relay can switch from a normally open state to a closed state. When the positive input terminal a and the negative input terminal b of the second optocoupler relay are energized, the positive output terminal c and the negative output terminal d of the second optocoupler relay can switch from a normally open state to a closed state, thereby forming an output path that can output a phase sequence detection signal to an external circuit.

[0006] Preferably, the AB current limiting component includes a first resistor, a first Zener diode, a second Zener diode, a second resistor, a third resistor, and a fourth resistor; the AB rectifier component includes a diode A; the AB filter component includes a first capacitor; the first resistor is connected to input port A; the first resistor, the first Zener diode, the second Zener diode, the diode A, the second resistor, and the third resistor are connected in series; the third resistor is also connected to the positive input terminal a of the first optocoupler relay; the negative input terminal b of the first optocoupler relay is connected to the fourth resistor; the fourth resistor is also connected to input port B; and the two ends of the first capacitor are respectively connected to the negative input terminal b of the first optocoupler relay and the output terminal of the second resistor.

[0007] The BC current limiting component includes a fourth resistor, a third Zener diode, a fourth Zener diode, a fifth resistor, a sixth resistor, and a seventh resistor. The BC rectifier component includes a diode C. The BC filter component includes a second capacitor. The fourth resistor, the third Zener diode, the fourth Zener diode, the diode C, the fifth resistor, and the sixth resistor are connected in series. The sixth resistor is also connected to the positive input terminal a of the second optocoupler relay. The negative input terminal b of the second optocoupler relay is connected to the seventh resistor. The seventh resistor is also connected to the input port C. The two ends of the second capacitor are connected to the negative input terminal b of the second optocoupler relay and the output terminal of the fifth resistor, respectively.

[0008] Preferably, a diode B is connected between the positive input terminal a and the negative input terminal b of the first optocoupler relay to limit the negative voltage from the negative input terminal b to the positive input terminal a of the first optocoupler relay to not exceed 0.7V; a diode D is connected between the positive input terminal a and the negative input terminal b of the second optocoupler relay to limit the negative voltage from the negative input terminal b to the positive input terminal a of the second optocoupler relay to not exceed 0.7V.

[0009] According to the above technical solution, the beneficial effects of the present invention are:

[0010] The phase sequence detection circuit of this invention connects the three input ports of a three-phase AC power supply to the input terminals of two optocoupler relays, forming two detection paths between the three input ports. The output terminals of the two optocoupler relays then form an output path for outputting a phase sequence detection signal to an external circuit. Only when the phase differences of all three input ports are normal, i.e., the three-phase input sequence of the three-phase AC power supply is normal, will the input terminals of the two optocoupler relays conduct simultaneously, thus enabling the output terminals of the two optocoupler relays to conduct simultaneously and output a phase sequence detection signal to the external circuit. Conversely, when the three-phase input sequence of the three-phase AC power supply is abnormal, the phase differences of the three input ports will also be incorrect, and the input terminals of the two optocoupler relays will not conduct simultaneously. Therefore, the output terminals of the two optocoupler relays will also not conduct simultaneously, and in this case, a phase sequence detection signal cannot be output to the external circuit. This invention utilizes the phase difference between the three-phase input phases and its own driving capability to determine whether the input terminal of the optocoupler relay is conducting normally. The detection accuracy is adjusted by the capacitor connected in parallel to the input terminal of the optocoupler relay. It eliminates the need for a smart chip to receive and process the electrical signals of the three-phase AC power supply. The presence or absence of a phase sequence detection signal can be used to determine whether there is an abnormality in the three-phase phase sequence of the three-phase AC power supply. Therefore, it eliminates the need for an external power supply to the smart chip, simplifies the structure of the detection circuit, reduces costs, avoids the working errors of the smart chip, and improves the reliability of the detection circuit. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the present invention.

[0012] The markings in the diagram are: 1. First resistor, 2. First Zener diode, 3. Second Zener diode, 4. Diode A, 5. Second resistor, 6. Third resistor, 7. First capacitor, 8. Diode B, 9. First optocoupler relay, 10. Fourth resistor, 11. Third Zener diode, 12. Fourth Zener diode, 13. Diode C, 14. Fifth resistor, 15. Sixth resistor, 16. Second capacitor, 17. Diode D, 18. Second optocoupler relay, 19. Seventh resistor. Detailed Implementation

[0013] Referring to the attached diagram, the specific implementation method is as follows:

[0014] A phase sequence detection circuit that requires no external power supply includes two optocoupler relays. The input port A of the three-phase AC power supply is connected to the positive input terminal a of the first optocoupler relay 9, and the input port B of the three-phase AC power supply is connected to the negative input terminal b of the first optocoupler relay 9, forming an AB detection path between input port A and input port B. The input port B of the three-phase AC power supply is also connected to the positive input terminal a of the second optocoupler relay 18, and the input port C of the three-phase AC power supply is connected to the negative input terminal b of the second optocoupler relay 18, forming a BC detection path between input port B and input port C.

[0015] The positive output terminal c of the first optocoupler relay 9 can output a positive electrical signal to an external circuit, and the negative output terminal d of the second optocoupler relay 18 can output a negative electrical signal to an external circuit. The negative output terminal d of the first optocoupler relay 9 and the positive output terminal c of the second optocoupler relay 18 are connected to each other.

[0016] When the positive input terminal a and the negative input terminal b of the first optocoupler relay 9 are energized, the positive output terminal c and the negative output terminal d of the first optocoupler relay 9 can switch from the normally open state to the closed state. When the positive input terminal a and the negative input terminal b of the second optocoupler relay 18 are energized, the positive output terminal c and the negative output terminal d of the second optocoupler relay 18 can switch from the normally open state to the closed state, thereby forming an output path that can output a phase sequence detection signal to an external circuit.

[0017] The AB detection path is connected to an AB current limiting component, an AB rectification component, and an AB filter component. The BC detection path is connected to a BC current limiting component, a BC rectification component, and a BC filter component. The AB current limiting component includes a first resistor 1, a first Zener diode 2, a second Zener diode 3, a second resistor 5, a third resistor 6, and a fourth resistor 10. The AB rectification component includes a diode A4. The AB filter component includes a first capacitor 7. The first resistor 1 is connected to input port A. The first resistor 1, the first Zener diode 2, the second Zener diode 3, the diode A4, the second resistor 5, and the third resistor 6 are connected in series. The third resistor 6 is also connected to the positive input terminal a of the first optocoupler relay 9. The negative input terminal b of the first optocoupler relay 9 is connected to the fourth resistor 10. The fourth resistor 10 is also connected to input port B. The two ends of the first capacitor 7 are connected to the negative input terminal b of the first optocoupler relay 9 and the output terminal of the second resistor 5, respectively.

[0018] The BC current limiting component includes a fourth resistor 10, a third Zener diode 11, a fourth Zener diode 12, a fifth resistor 14, a sixth resistor 15, and a seventh resistor 19. The BC rectifier component includes a diode C13, and the BC filter component includes a second capacitor 16. As described above, the fourth resistor 10 is connected to the input port B. Then, the fourth resistor 10, the third Zener diode 11, the fourth Zener diode 12, the diode C13, the fifth resistor 14, and the sixth resistor 15 are connected in series. The sixth resistor 15 is also connected to the positive input terminal a of the second optocoupler relay 18. The negative input terminal b of the second optocoupler relay 18 is connected to the seventh resistor 19. The seventh resistor 19 is also connected to the input port C. The two ends of the second capacitor 16 are respectively connected to the negative input terminal b of the second optocoupler relay 18 and the output terminal of the fifth resistor 14.

[0019] A diode B8 is connected between the positive input terminal a and the negative input terminal b of the first optocoupler relay 9 to limit the negative voltage from the negative input terminal b to the positive input terminal a of the first optocoupler relay 9 to not exceed 0.7V. A diode D17 is connected between the positive input terminal a and the negative input terminal b of the second optocoupler relay 18 to limit the negative voltage from the negative input terminal b to the positive input terminal a of the second optocoupler relay 18 to not exceed 0.7V.

[0020] The working method of this embodiment is as follows: when the three-phase input phase sequence is normal, the phase difference between input port A and input port B is limited by the first resistor 1, the first Zener diode 2, the second Zener diode 3, the second resistor 5, and the third resistor 6, rectified by the diode A4, and filtered by the first capacitor 7, and then drives the input terminal of the first optocoupler relay 9 to conduct.

[0021] The phase difference between input port B and input port C, after being limited by the fourth resistor 10, the third Zener diode 11, the fourth Zener diode 12, the fifth resistor 14, and the sixth resistor 15, rectified by the diode C13, and filtered by the second capacitor 16, drives the input terminal of the second optocoupler relay 18 to conduct.

[0022] When the input terminals of the first optocoupler relay 9 and the second optocoupler relay 18 are simultaneously turned on, the corresponding output terminals of the first optocoupler relay 9 and the second optocoupler relay 18 are also simultaneously turned on, thus enabling the output of a phase sequence detection signal to an external circuit.

[0023] When the three-phase input phase sequence is abnormal, the input terminals of the first optocoupler relay 9 and the second optocoupler relay 18 cannot be turned on simultaneously, so the output terminals of the first optocoupler relay 9 and the second optocoupler relay 18 cannot be turned on simultaneously either. At this time, the phase sequence detection signal cannot be output to the external circuit, and it can be determined that there is an error in the phase sequence of the three-phase AC power.

Claims

1. A phase sequence detection circuit that requires no external power supply, characterized in that: It includes two optocoupler relays. The input port A of the three-phase AC power supply is connected to the positive input terminal a of the first optocoupler relay (9), and the input port B of the three-phase AC power supply is connected to the negative input terminal b of the first optocoupler relay (9), forming an AB detection path between input port A and input port B. The input port B of the three-phase AC power supply is also connected to the positive input terminal a of the second optocoupler relay (18), and the input port C of the three-phase AC power supply is connected to the negative input terminal b of the second optocoupler relay (18), forming a BC detection path between input port B and input port C. An AB current limiting component, an AB rectification component, and an AB filter component are connected on the AB detection path, and a BC current limiting component, a BC rectification component, and a BC filter component are connected on the BC detection path. The positive output terminal c of the first optocoupler relay (9) can output a positive electrical signal to an external circuit, and the negative output terminal d of the second optocoupler relay (18) can output a negative electrical signal to an external circuit. The negative output terminal d of the first optocoupler relay (9) and the positive output terminal c of the second optocoupler relay (18) are connected to each other. When the positive input terminal a and the negative input terminal b of the first optocoupler relay (9) are energized, the positive output terminal c and the negative output terminal d of the first optocoupler relay (9) can switch from the normally open state to the closed state. When the positive input terminal a and the negative input terminal b of the second optocoupler relay (18) are energized, the positive output terminal c and the negative output terminal d of the second optocoupler relay (18) can switch from the normally open state to the closed state, thereby forming an output path that can output a phase sequence detection signal to an external circuit. The AB current limiting component includes a first resistor (1), a first Zener diode (2), a second Zener diode (3), a second resistor (5), a third resistor (6), and a fourth resistor (10). The AB rectifier component includes a diode A (4). The AB filter component includes a first capacitor (7). The first resistor (1) is connected to the input port A. The first resistor (1), the first Zener diode (2), the second Zener diode (3), the diode A (4), the second resistor (5), and the third resistor (6) are connected in series. The third resistor (6) is also connected to the positive input terminal a of the first optocoupler relay (9). The negative input terminal b of the first optocoupler relay (9) is connected to the fourth resistor (10). The fourth resistor (10) is also connected to the input port B. The two ends of the first capacitor (7) are respectively connected to the negative input terminal b of the first optocoupler relay (9) and the output terminal of the second resistor (5). The BC current limiting component includes a fourth resistor (10), a third Zener diode (11), a fourth Zener diode (12), a fifth resistor (14), a sixth resistor (15), and a seventh resistor (19). The BC rectifier component includes a diode C (13). The BC filter component includes a second capacitor (16). The fourth resistor (10), the third Zener diode (11), the fourth Zener diode (12), the diode C (13), the fifth resistor (14), and the sixth resistor (15) are connected in series. The sixth resistor (15) is also connected to the positive input terminal a of the second optocoupler relay (18). The negative input terminal b of the second optocoupler relay (18) is connected to the seventh resistor (19). The seventh resistor (19) is also connected to the input port C. The two ends of the second capacitor (16) are connected to the negative input terminal b of the second optocoupler relay (18) and the output terminal of the fifth resistor (14), respectively.

2. The phase sequence detection circuit that requires no external power supply according to claim 1, characterized in that: A diode B (8) is connected between the positive input terminal a and the negative input terminal b of the first optocoupler relay (9) to limit the negative voltage from the negative input terminal b to the positive input terminal a of the first optocoupler relay (9) to not exceed 0.7V; a diode D (17) is connected between the positive input terminal a and the negative input terminal b of the second optocoupler relay (18) to limit the negative voltage from the negative input terminal b to the positive input terminal a of the second optocoupler relay (18) to not exceed 0.7V.

Images