Three-phase alternating current power supply reverse phase sequence and open phase detection circuit

Abstract

The invention discloses a three-phase alternating current power supply reverse phase sequence and open phase detection circuit which comprises a differential operation phase shift circuit, a comparison operation circuit and a detection output circuit. The differential operation phase-shifting circuit is connected to the input end of a three-phase alternating-current power supply, and after sampling, filtering and phase shifting are conducted on each phase of the three-phase alternating-current power supply, two phases are taken for differential operation, and differential voltages Ucb and Uab are obtained. The comparison operation circuit is connected to the output end of the differential operation phase shift circuit, and performs comparison operation on the differential voltage Ucb and the differential voltage Uab to obtain a comparison operation output voltage Ucb-ab; the voltage Uout1 is compared with a threshold voltage Uref, and a voltage Uout1 is obtained; and the detection output circuit is connected to the output end of the comparison operation circuit, and when the three-phase alternating-current power supply has the abnormal conditions of reverse phase sequence and open phase and the voltage Uout1 is a rectangular wave pulse voltage, the voltage is subjected to detection processing to obtain a constant high-level output voltage Uout. The circuit detects the abnormal state of the input voltage by performing phase shifting and comparison on a three-phase alternating current power supply.

Description

Technical Field

[0001] The present invention belongs to the field of electronic detection circuits, and particularly relates to the reverse phase sequence and open phase detection of a three-phase AC power supply. Background Art

[0002] For three-phase AC electrical equipment, normal power supply input is a necessary condition for the equipment to normally achieve its functional performance. When abnormal power supply situations such as reverse phase sequence connection or open phase occur in the three-phase AC power supply, the vast majority of electrical equipment cannot operate normally. If detection and protection are not carried out in a timely manner, it will seriously lead to equipment damage and even trigger secondary accidents. Therefore, the detection of reverse phase sequence and open phase of the three-phase AC power supply is particularly crucial and important in the product safety design.

[0003] The existing designs for open phase detection and protection of three-phase AC power supplies mainly have the following two forms: 1) Rectify the three-phase AC power supply, and then perform voltage division, filtering, comparison, etc. For example, patent number CN 113884777A discloses a three-phase power supply open phase detection circuit and a high-voltage frequency converter, which includes a three-phase rectification unit, a differential detection unit, an open phase detection unit, a control unit, etc. The design method and circuit principle of this form are complex, reducing the overall reliability of the system; 2) Directly sample the three-phase AC power supply through devices such as resistor voltage division and optocoupler isolation, and then take measures such as signal processing and comparison to complete open phase detection. For example, patent number CN 114280386A discloses a three-phase power failure and open phase detection circuit, method, and control cabinet. This form can detect power failure and open phase faults, but the detection factors are single and it cannot effectively identify situations such as reverse phase sequence and abnormal power supply frequency. Summary of the Invention

[0004] The present invention provides a reverse phase sequence and open phase detection circuit for a three-phase AC power supply, which detects the abnormal state of the input voltage by means of phase shift and comparison of the three-phase AC power supply.

[0005] A technical solution for a reverse phase sequence and open phase detection circuit of a three-phase AC power supply is as follows: It includes a differential operation phase shift circuit, a comparison operation circuit, and a detection output circuit;

[0006] The differential operation phase shift circuit is connected to the three-phase AC power supply input terminal. After sampling, filtering, and phase shifting each phase of the three-phase AC power supply, two phases are respectively taken for differential operation to obtain differential voltages U cb and U ab , and this differential voltage is a sinusoidal AC voltage;

[0007] The comparison operation circuit is connected to the output terminal of the differential operation phase shift circuit, and performs comparison operation on the differential voltages U cb and U ab to obtain a comparison operation output voltage U cb-ab; Then compare it with the threshold voltage U ref to obtain the voltage U out_1 ; If there are no abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, then the output voltage U cb-ab is less than the threshold voltage U ref , and this voltage U out_1 is at a low level; If there are abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, then the output voltage U cb-ab is greater than the threshold voltage U ref , and this voltage U out_1 is a rectangular pulse voltage;

[0008] The detection output circuit is connected to the output end of the comparison operation circuit. If there are no abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, when the voltage U out_1 is at a low level, the detection output voltage is always at a low level; When there are abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, when the voltage U out_1 is a rectangular wave pulse voltage, perform detection processing on this voltage to obtain a constant high-level output voltage U out .

[0009] Furthermore, the differential operation phase-shifting circuit is composed of a sampling and filtering unit, an operational amplification unit, and a first-order low-pass filtering unit;

[0010] The sampling and filtering unit is composed of resistors R1 to R8 and capacitors C1 to C5. One end of the resistor R1 is connected to the three-phase power input terminal C, and the other end is connected to the common terminal of the resistor R4, the capacitor C1, and the non-inverting input terminal of the operational amplifier U1A. The other end of the resistor R4 and the other end of the capacitor C1 are connected to the bias voltage of 2.5V;

[0011] One end of the resistor R2 is connected to the three-phase power input terminal B, and the other end is connected to the common terminal of the resistor R3, the capacitor C2, and the inverting input terminal of the operational amplifier U1A. The other end of the resistor R3 and the other end of the capacitor C2 are connected to the output terminal of the operational amplifier U1A;

[0012] One end of the resistor R5 is connected to the three-phase power input terminal A, and the other end is connected to the common terminal of the resistor R8, the capacitor C3, and the non-inverting input terminal of the operational amplifier U1B. The other end of the resistor R8 and the other end of the capacitor C3 are connected to the bias voltage of 2.5V;

[0013] One end of the resistor R6 is connected to the three-phase power input terminal B, and the other end is connected to the common terminal of the resistor R7, the capacitor C4, and the inverting input terminal of the operational amplifier U1B. The other end of the resistor R7 and the other end of the capacitor C4 are connected to the output terminal of the operational amplifier U1B;

[0014] The operational amplifier unit consists of operational amplifiers U1A and U1B; the non-inverting input terminal of operational amplifier U1A is connected to the common terminal of resistor R1, resistor R4, and capacitor C1, the inverting input terminal of operational amplifier U1A is connected to the common terminal of resistor R2, resistor R3, and capacitor C2, and the output terminal of operational amplifier U1A is connected to the input terminal of the first-order low-pass filter unit;

[0015] The non-inverting input terminal of operational amplifier U1B is connected to the common terminal of resistor R5, resistor R8, and capacitor C3, the inverting input terminal of operational amplifier U1B is connected to the common terminal of resistor R6, resistor R7, and capacitor C4, and the output terminal of operational amplifier U1B is connected to the input terminal of the comparison operation circuit;

[0016] The first-order low-pass filter unit consists of resistor R9 and capacitor C5. One end of resistor R9 is connected to the output terminal of operational amplifier U1A, the other end is connected to capacitor C5 and also to the input terminal of the comparison operation circuit, and the other end of capacitor C5 is connected to the ground terminal.

[0017] Further, the comparison operation circuit consists of a differential operation unit and a comparison unit;

[0018] The differential operation unit consists of resistors R10 to R13 and operational amplifier U2A; one end of resistor R10 is connected to the output terminal of the first-order low-pass filter unit, the other end is connected to the common terminal of resistor R12 and the non-inverting input terminal of operational amplifier U2A, and the other end of resistor R12 is connected to the ground terminal; one end of resistor R11 is connected to the output terminal of operational amplifier U1B, the other end is connected to the common terminal of resistor R13 and the inverting input terminal of operational amplifier U2A, and the other end of resistor R13 is connected to the output terminal of operational amplifier U2A;

[0019] The comparison unit consists of operational amplifier U2B. The non-inverting input terminal of operational amplifier U2B is connected to the output terminal of operational amplifier U2A, the inverting input terminal is connected to the threshold voltage U ref , and the output terminal is connected to the input terminal of the detection output circuit.

[0020] Further, the detection output circuit consists of a detection unit and an output unit;

[0021] The detection unit consists of diode VD1, resistor R14, resistor R15, and capacitor C6. The anode of diode VD1 is connected to the output terminal of operational amplifier U2B, the cathode is connected to one end of resistor R14, the other end of resistor R14 is connected to the common terminal of resistor R15 and capacitor C16 and also to the input terminal of the output unit; the other end of resistor R15 and the other end of capacitor C16 are commonly connected to the ground terminal;

[0022] The output unit consists of an operational amplifier U3A and a resistor R16; the non-inverting input terminal of the operational amplifier U3A is connected to the output terminal of the detection unit and one end of the resistor R16, the inverting input terminal is connected to the voltage threshold of 2.5V, and the output terminal is connected to the other end of the resistor R16 and serves as the output voltage of the circuit.

[0023] Compared with the existing three-phase AC power supply reverse phase sequence and open-phase detection circuit, the present invention has the following beneficial effects:

[0024] 1. By sampling, filtering, and phase-shifting and comparing the three-phase AC power supply, this processing method can simultaneously detect various power supply abnormalities such as reverse phase sequence, open phase, and frequency abnormality of the three-phase power supply, improving the reliability of electrical equipment.

[0025] 2. The present invention avoids the use of a control chip and software algorithm, and is implemented using an analog circuit. The circuit principle design is simple, with fewer components used, reducing the implementation difficulty and application cost.

[0026] 3. The circuit parameters of the present invention can be adjusted according to the power supply situation, with strong applicability. Description of the Drawings

[0027] Figure 1 Schematic diagram of the circuit structure. Detailed Embodiment

[0028] The present invention will be further described in detail below with reference to the drawings.

[0029] The present invention provides a three-phase AC power supply reverse phase sequence and open-phase detection circuit, which detects the abnormal state of the input voltage by phase-shifting and comparing the three-phase AC power supply.

[0030] As Figure 1 shown, the present invention is implemented as follows: a three-phase AC power supply reverse phase sequence and open-phase detection circuit includes: a differential operation phase-shifting circuit, a comparison operation circuit, and a detection output circuit.

[0031] Differential operation phase-shifting circuit: The differential operation phase-shifting circuit is connected to the three-phase AC power supply input terminal. After sampling, filtering, and phase-shifting each phase of the three-phase AC power supply, two phases are respectively taken for differential operation to obtain differential voltages U cb and U ab , and this differential voltage is a sinusoidal AC voltage;

[0032] Comparison operation circuit: The comparison operation circuit is connected to the output terminal of the differential operation phase-shifting circuit, and compares and operates the differential voltages U cb and U ab to obtain a comparison operation output voltage U cb-ab; and then compare it with the threshold voltage U ref to obtain the voltage U out_1 . If there are no abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, the output voltage U cb-ab is less than the threshold voltage U ref , and this voltage U out_1 is at a low level; if there are abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, the output voltage U cb-ab is greater than the threshold voltage U ref , and this voltage U out_1 is a rectangular pulse voltage;

[0033] Detection output circuit: The detection output circuit is connected to the output end of the comparison operation circuit. If there are no abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, when the voltage U out_1 is at a low level, the detection output voltage is always at a low level; when there are abnormal conditions such as reverse phase sequence or phase loss in the three-phase AC power supply, when the voltage U out_1 is a rectangular wave pulse voltage, the voltage is detected to obtain a constant high-level output voltage U out .

[0034] Furthermore, the differential operation phase-shifting circuit consists of a sampling and filtering unit, an operational amplifier unit, and a first-order low-pass filtering unit; the sampling and filtering unit consists of resistors R1 to R8 and capacitors C1 to C5. One end of resistor R1 is connected to the three-phase power input terminal C, and the other end is connected to the common terminal of resistor R4, capacitor C1, and the non-inverting input terminal of operational amplifier U1A. The other end of resistor R4 and the other end of capacitor C1 are connected to the bias voltage of 2.5V.

[0035] One end of resistor R2 is connected to the three-phase power input terminal B, and the other end is connected to the common terminal of resistor R3, capacitor C2, and the inverting input terminal of operational amplifier U1A. The other end of resistor R3 and the other end of capacitor C2 are connected to the output terminal of operational amplifier U1A.

[0036] One end of resistor R5 is connected to the three-phase power input terminal A, and the other end is connected to the common terminal of resistor R8, capacitor C3, and the non-inverting input terminal of operational amplifier U1B. The other end of resistor R8 and the other end of capacitor C3 are connected to the bias voltage of 2.5V.

[0037] One end of resistor R6 is connected to the three-phase power input terminal B, and the other end is connected to the common terminal of resistor R7, capacitor C4, and the inverting input terminal of operational amplifier U1B. The other end of resistor R7 and the other end of capacitor C4 are connected to the output terminal of operational amplifier U1B.

[0038] The operational amplifier unit consists of operational amplifiers U1A and U1B. The non-inverting input terminal of operational amplifier U1A is connected to the common terminal of resistor R1, resistor R4, and capacitor C1. The inverting input terminal of operational amplifier U1A is connected to the common terminal of resistor R2, resistor R3, and capacitor C2. The output terminal of operational amplifier U1A is connected to the input terminal of the first-order low-pass filter unit.

[0039] The non-inverting input terminal of operational amplifier U1B is connected to the common terminal of resistor R5, resistor R8, and capacitor C3. The inverting input terminal of operational amplifier U1B is connected to the common terminal of resistor R6, resistor R7, and capacitor C4. The output terminal of operational amplifier U1B is connected to the input terminal of the comparison operation circuit.

[0040] The first-order low-pass filter unit consists of resistor R9 and capacitor C5. One end of resistor R9 is connected to the output terminal of operational amplifier U1A, the other end is connected to capacitor C5, and is also connected to the input terminal of the comparison operation circuit. The other end of capacitor C5 is connected to the ground terminal.

[0041] Furthermore, the comparison operation circuit consists of a differential operation unit and a comparison unit. The differential operation unit consists of resistors R10 to R13 and operational amplifier U2A. One end of resistor R10 is connected to the output terminal of the first-order low-pass filter unit, and the other end is connected to the common terminal of resistor R12 and the non-inverting input terminal of operational amplifier U2A. The other end of resistor R12 is connected to the ground terminal. One end of resistor R11 is connected to the output terminal of operational amplifier U1B, and the other end is connected to the common terminal of resistor R13 and the inverting input terminal of operational amplifier U2A. The other end of resistor R13 is connected to the output terminal of operational amplifier U2A.

[0042] The comparison unit consists of operational amplifier U2B. The non-inverting input terminal of operational amplifier U2B is connected to the output terminal of operational amplifier U2A, and the inverting input terminal is connected to the threshold voltage U ref , and the output terminal is connected to the input terminal of the detection output circuit.

[0043] Furthermore, the detection output circuit consists of a detection unit and an output unit. The detection unit consists of diode VD1, resistor R14, resistor R15, and capacitor C6. The anode of diode VD1 is connected to the output terminal of operational amplifier U2B, the cathode is connected to one end of resistor R14, and the other end of resistor R14 is connected to the common terminal of resistor R15 and capacitor C16, and is also connected to the input terminal of the output unit. The other end of resistor R15 and the other end of capacitor C16 are jointly connected to the ground terminal.

[0044] The output unit consists of operational amplifier U3A and resistor R16. The non-inverting input terminal of operational amplifier U3A is connected to the output terminal of the detection unit and one end of resistor R16. The inverting input terminal is connected to the voltage threshold of 2.5V, and the output terminal is connected to the other end of resistor R16 and serves as the output voltage of the circuit.

[0045] A three-phase AC power supply reverse phase sequence and open-phase detection circuit provided by the present invention can timely and efficiently detect the reverse phase sequence and open-phase conditions of the three-phase power supply through processing of sampling and filtering, phase shift comparison, and detection output of the three-phase power input, and output a high-level signal to facilitate further circuit protection. This circuit is implemented using analog circuits, avoiding the use of control chips and software algorithms. At the same time, the circuit principle design is simple, with fewer components used, low cost and easy to implement, and can detect various power supply abnormalities such as reverse phase sequence, open phase, and frequency abnormality of the three-phase power supply, greatly improving the reliability and safety of electrical equipment.

[0046] The key improvement points of the present invention:

[0047] 1. The present invention innovatively proposes a processing method of phase shift comparison after sampling and filtering the three-phase AC power supply. This processing method can detect various power supply abnormalities such as reverse phase sequence, open phase, and frequency abnormality of the three-phase power supply, greatly improving the reliability and safety of electrical equipment;

[0048] 2. By adjusting the sampling, filtering, and phase shift parameters, the present invention can adapt to different three-phase AC power supplies, so the present invention has strong applicability;

[0049] The above specific embodiments are only for explaining and illustrating the technical solution of the present invention, but do not constitute a limitation on the protection scope of the claims. Those skilled in the art should understand that any new technical solution obtained by making any simple deformation or replacement on the basis of the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A three-phase AC power supply reverse phase sequence and phase loss detection circuit, characterized in that: It includes a differential operation phase shift circuit, a comparison operation circuit, and a detection output circuit; The differential operation phase shift circuit is connected to the input end of the three-phase AC power supply. After sampling, filtering and phase shifting each phase of the three-phase AC power supply, two phases are taken for differential operation to obtain a differential voltage U cb and U ab , the differential voltage is a sinusoidal AC voltage; The comparison operation circuit is connected to the output end of the differential operation phase shift circuit to convert the differential voltage U cb and U ab Perform comparison operation to obtain the comparison operation output voltage U cb-ab ; Then with the threshold voltage U ref By comparison, we get voltage U out_1 ; If the three-phase AC power supply does not have abnormal conditions such as reverse phase sequence and phase loss, the output voltage U cb-ab Less than the threshold voltage U ref , the voltage U out_1 is low level; if the three-phase AC power supply has reverse phase sequence or phase loss abnormality, the output voltage U cb-ab Greater than the threshold voltage U ref , the voltage U out_1 is a rectangular pulse voltage; The detection output circuit is connected to the output end of the comparison operation circuit. If there is no reverse phase sequence or phase loss abnormality in the three-phase AC power supply, the voltage U out_1 When the three-phase AC power supply has a reverse phase sequence or a phase loss, the voltage U out_1 When it is a rectangular wave pulse voltage, the voltage is detected to obtain a constant high-level output voltage U out .

2. A three-phase AC power supply reverse phase sequence and phase loss detection circuit according to claim 1, characterized in that: The differential operational phase shift circuit is composed of a sampling filter unit, an operational amplifier unit and a first-order low-pass filter unit; The sampling filter unit is composed of resistors R1 to R8 and capacitors C1 to C5. One end of the resistor R1 is connected to the three-phase power input terminal C, and the other end is connected to the common end of the resistor R4, the capacitor C1, and the in-phase input terminal of the operational amplifier U1A. The other end of the resistor R4 and the other end of the capacitor C1 are connected to the bias voltage 2.5V. One end of the resistor R2 is connected to the three-phase power supply input terminal B, and the other end is connected to the common end of the resistor R3, the capacitor C2, and the inverting input terminal of the operational amplifier U1A. The other end of the resistor R3 and the other end of the capacitor C2 are connected to the output terminal of the operational amplifier U1A. One end of the resistor R5 is connected to the three-phase power input terminal A, and the other end is connected to the common end of the resistor R8, the capacitor C3, and the in-phase input terminal of the operational amplifier U1B. The other end of the resistor R8 and the other end of the capacitor C3 are connected to the bias voltage 2.5V; One end of the resistor R6 is connected to the three-phase power input terminal B, and the other end is connected to the common end of the resistor R7, the capacitor C4, and the inverting input terminal of the operational amplifier U1B. The other end of the resistor R7 and the other end of the capacitor C4 are connected to the output terminal of the operational amplifier U1B. The operational amplifier unit is composed of an operational amplifier U1A and an operational amplifier U1B; the non-inverting input terminal of the operational amplifier U1A is connected to the common terminal of the resistor R1, the resistor R4 and the capacitor C1, the inverting input terminal of the operational amplifier U1A is connected to the common terminal of the resistor R2, the resistor R3 and the capacitor C2, and the output terminal of the operational amplifier U1A is connected to the input terminal of the first-order low-pass filter unit; The non-inverting input terminal of the operational amplifier U1B is connected to the common terminal of the resistor R5, the resistor R8, and the capacitor C3, the inverting input terminal of the operational amplifier U1B is connected to the common terminal of the resistor R6, the resistor R7, and the capacitor C4, and the output terminal of the operational amplifier U1B is connected to the input terminal of the comparison operation circuit; The first-order low-pass filter unit is composed of a resistor R9 and a capacitor C5. One end of the resistor R9 is connected to the output end of the operational amplifier U1A, and the other end is connected to the capacitor C5 and to the input end of the comparison operation circuit. The other end of the capacitor C5 is connected to the ground.

3. A three-phase AC power supply reverse phase sequence and phase loss detection circuit according to claim 1, characterized in that: The comparison operation circuit is composed of a differential operation unit and a comparison unit; The differential operation unit is composed of resistors R10 to R13 and an operational amplifier U2A; one end of the resistor R10 is connected to the output end of the first-order low-pass filter unit, and the other end is connected to the common end of the resistor R12 and the in-phase input end of the operational amplifier U2A, and the other end of the resistor R12 is connected to the ground; one end of the resistor R11 is connected to the output end of the operational amplifier U1B, and the other end is connected to the common end of the resistor R13 and the inverting input end of the operational amplifier U2A, and the other end of the resistor R13 is connected to the output end of the operational amplifier U2A; The comparison unit is composed of an operational amplifier U2B, the non-inverting input terminal of the operational amplifier U2B is connected to the output terminal of the operational amplifier U2A, and the inverting input terminal is connected to the threshold voltage U ref , the output end is connected to the input end of the detection output circuit.

4. A three-phase AC power supply reverse phase sequence and phase loss detection circuit according to claim 1, characterized in that: The detection output circuit is composed of a detection unit and an output unit; The detection unit is composed of a diode VD1, a resistor R14, a resistor R15, and a capacitor C6. The anode of the diode VD1 is connected to the output end of the operational amplifier U2B, and the cathode is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the common end of the resistor R15 and the capacitor C16, and is connected to the input end of the output unit; the other end of the resistor R15 and the other end of the capacitor C16 are connected to the ground together; The output unit is composed of an operational amplifier U3A and a resistor R16; the non-inverting input terminal of the operational amplifier U3A is connected to the output terminal of the detection unit and one end of the resistor R16, the inverting input terminal is connected to the voltage threshold 2.5V, and the output terminal is connected to the other end of the resistor R16 and serves as the circuit output voltage.

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