A three-phase power supply input open-phase detection circuit

Abstract

The utility model provides a kind of three-phase power input open-phase detection circuit, including input power unit, uncontrolled rectification unit and open-phase detection unit;The input power unit is connected with uncontrolled rectification unit, open-phase detection unit respectively, wherein, input power unit is configured as output voltage to uncontrolled rectification unit, uncontrolled rectification unit is as the load end of input power unit, the open-phase detection unit is configured as the output voltage of detection input power unit, and output comparison signal to external control unit;Open-phase detection unit includes diode D7, D8, D9, voltage dividing resistor circuit, resistance R7, R8, voltage dividing resistor R6, R9, R10, capacitor C2, C3 and comparator U1A;The circuit is by setting open-phase detection unit, and by the input voltage difference of voltage open-phase when and normal working time of input power unit, to carry out voltage dividing sampling, the value of comparator is pre-set to judge whether open-phase, it has circuit simple, low in cost, reliability and so on advantages.

Description

Technical Field

[0001] This utility model relates to the field of electronic power technology, and in particular to a three-phase power input phase loss detection circuit. Background Technology

[0002] In three-phase power input devices, a missing phase can cause an imbalance in the three-phase power supply, leading to equipment damage. Therefore, phase loss detection of the three-phase input power supply is necessary. Existing three-phase input power supply phase loss detection circuits suffer from drawbacks such as high cost, complex circuitry, increased equipment costs, and reduced equipment reliability. For example, Chinese invention patent publication number CN119986172A discloses a phase loss detection method, device, and frequency converter for three-phase power supplies. The method includes: acquiring the three-phase voltage composite vector of the three-phase power supply under test; acquiring the composite vector statistical value of the three-phase voltage composite vector within a preset time period; comparing the composite vector statistical value with a preset standard voltage composite result; and determining a phase loss threshold based on the comparison result and a preset comparison threshold; and generating a warning signal for a phase loss in the three-phase power supply under test when the three-phase voltage composite vector is detected to be less than the phase loss threshold at any given moment. While this method can improve detection accuracy, it is relatively complex.

[0003] Therefore, in view of the problems existing in the prior art, it is of great importance to provide a three-phase power input phase loss detection circuit technology that is highly reliable, reduces hardware costs, and has a simple circuit structure. Utility Model Content

[0004] The purpose of this invention is to avoid the shortcomings of the prior art and to provide a three-phase power input phase loss detection circuit. This circuit detects whether the voltage of the input power unit is missing a phase by setting up a phase loss detection unit and through a specific detection circuit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A three-phase power input phase loss detection circuit includes an input power supply unit, an uncontrolled rectifier unit, and a phase loss detection unit. The input power supply unit is connected to the uncontrolled rectifier unit and the phase loss detection unit, respectively. The input power supply unit is configured to output voltage to the uncontrolled rectifier unit, which serves as the load terminal of the input power supply unit. The phase loss detection unit is configured to detect the output voltage of the input power supply unit and output a comparison signal to an external control unit.

[0007] The phase loss detection unit includes diodes D7, D8, and D9, a voltage divider resistor circuit, resistors R7 and R8, voltage divider resistors R6, R9, and R10, capacitors C2 and C3, and comparator U1A.

[0008] The voltage divider resistor circuit is formed by connecting one or more voltage divider resistors in series. The anodes of diodes D7, D8, and D9 are connected to the output terminals of the input power supply unit to sample the output voltage of the input power supply unit. The leads of diodes D7, D8, and D9 connected together are connected to the voltage divider resistor circuit, and the connection point of the circuit after connecting the cathodes of diodes D7, D8, and D9 is used to connect to an external oscilloscope to obtain the voltage waveform at that connection point. The other end of the voltage divider resistor circuit is connected to resistor R7, and the other end of resistor R7 is connected to capacitor C2. The inverting input of comparator U1A is connected to the voltage divider resistor R6 in parallel across the connection line between resistor R7 and capacitor C2; the non-inverting input of comparator U1A is connected to voltage divider resistors R9 and R10 respectively, with the other end of voltage divider resistor R9 grounded and the other end of R10 connected to power supply VCC; the output of comparator U1A is connected to resistor R8, with the other end of resistor R8 connected to capacitor C3, and the other end of capacitor C3 grounded; a connection point is taken on the connection line between resistor R8 and capacitor C3 for connection to an external oscilloscope to obtain the waveform of the output comparison signal of comparator U1A;

[0009] The resistor R7 and capacitor C2, and the resistor R8 and capacitor C3 respectively form a first-order low-pass filter, which is used to filter out signal noise in the circuit.

[0010] The voltage divider resistor circuit described above is formed by four voltage divider resistors R1, R3, R4, and R5 connected in series. Voltage divider resistor R1 serves as the input terminal of the voltage divider resistor circuit and is connected to the circuit after the negative terminals of diodes D7, D8, and D9 are connected. Voltage divider resistor R5 serves as the output terminal of the voltage divider resistor circuit and is connected to resistor R7.

[0011] The above-mentioned input power supply unit includes three-phase power input terminals V1, V2, and V3, and the three-phase power input terminals V1, V2, and V3 are respectively connected to the positive terminals of diodes D7, D8, and D9.

[0012] The circuits connecting the three-phase power input terminals V1, V2, and V3 to the positive terminals of diodes D7, D8, and D9 are also equipped with switches S1A, S1B, and S1C, respectively, to control the on / off state of the circuits.

[0013] The uncontrolled rectifier unit described above includes six high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A, a capacitor C1, and an equivalent resistor R2. The cathodes of the high-voltage rectifier diodes D3A, D1A, and D2A are connected together to form a common cathode group, and the anodes of the high-voltage rectifier diodes D4A, D6A, and D5A are connected together and grounded to form a common anode group. The anode of the high-voltage rectifier diode D3A is connected to the cathode of D4A, and its lead is connected to the three-phase power input terminal V1. The anode of the high-voltage rectifier diode D1A is connected to the cathode of D6A, and its lead is connected to the three-phase power input terminal V2. The anode of the high-voltage rectifier diode D2A is connected to the cathode of D5A, and its lead is connected to the three-phase power input terminal V3.

[0014] After the capacitor C1 is connected in parallel with the equivalent resistance R2, its two ends are connected in parallel to the cathode of the high-voltage rectifier diode D2A and the anode of D5A.

[0015] Preferably, the high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A are of model DF10S / 45.

[0016] Preferably, the diodes D7, D8, and D9 are of model 1N4007-E3 / 54.

[0017] Preferably, the comparator U1A is model LM2903DG.

[0018] The beneficial effects of this utility model are:

[0019] This utility model provides a three-phase power input phase loss detection circuit. The circuit sets up a phase loss detection unit and performs voltage division sampling by measuring the difference between the input voltage of the power supply unit when a phase is lost and when it is working normally. The value of the comparator is preset to determine whether a phase is lost. It has the advantages of simple circuit, low cost and high reliability. Attached Figure Description

[0020] Figure 1 A circuit module structure diagram of the three-phase power input phase loss detection circuit provided in this embodiment of the utility model;

[0021] Figure 2 A circuit structure diagram of a three-phase power input phase loss detection circuit provided for an embodiment of this utility model;

[0022] Figure 3 Example diagram of the voltage waveform at node 6 of the three-phase power input phase loss detection circuit under normal input conditions, provided for an embodiment of this utility model;

[0023] Figure 4Example diagram of voltage waveform at node 6 in the input phase loss state of the three-phase power input phase loss detection circuit provided in this embodiment of the utility model;

[0024] Figure 5 A waveform example of the comparator U1A output signal in the normal state of the three-phase input of the three-phase power input phase loss detection circuit provided in this embodiment of the utility model;

[0025] Figure 6 This is an example waveform diagram of the comparator U1A output signal in the three-phase input phase loss detection circuit provided in this embodiment of the utility model. Detailed Implementation

[0026] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0027] like Figure 1-2 As shown, this embodiment provides a three-phase power input phase loss detection circuit, including an input power supply unit, an uncontrolled rectifier unit, and a phase loss detection unit; the input power supply unit is connected to the uncontrolled rectifier unit and the phase loss detection unit respectively, wherein the input power supply unit is configured to output voltage to the uncontrolled rectifier unit, the uncontrolled rectifier unit serves as the load terminal of the input power supply unit, and the phase loss detection unit is configured to detect the output voltage of the input power supply unit and output a comparison signal to an external control unit;

[0028] In this embodiment, the input power unit includes three-phase power input terminals V1, V2, and V3, and the three-phase power input terminals V1, V2, and V3 are respectively connected to the positive terminals of diodes D7, D8, and D9; furthermore, switches S1A, S1B, and S1C are respectively provided on the lines connecting the three-phase power input terminals V1, V2, and V3 to the positive terminals of diodes D7, D8, and D9 to control the on / off state of the lines.

[0029] The uncontrolled rectifier unit includes six high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A, a capacitor C1, and an equivalent resistor R2. The cathodes of high-voltage rectifier diodes D3A, D1A, and D2A are connected together to form a common cathode group, and the anodes of high-voltage rectifier diodes D4A, D6A, and D5A are connected together and grounded to form a common anode group. The anode of high-voltage rectifier diode D3A is connected to the cathode of D4A, and its lead is connected to the three-phase power input terminal V1. The anode of high-voltage rectifier diode D1A is connected to the cathode of D6A, and its lead is connected to the three-phase power input terminal V2. The anode of high-voltage rectifier diode D2A is connected to the cathode of D5A, and its lead is connected to the three-phase power input terminal V3. After capacitor C1 and equivalent resistor R2 are connected in parallel, their two ends are connected in parallel to the cathode of high-voltage rectifier diode D2A and the anode of high-voltage rectifier diode D5A. In this circuit structure, the high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A are model DF10S / 45.

[0030] The phase loss detection unit includes diodes D7, D8, and D9, a voltage divider resistor circuit (four voltage divider resistors R1, R3, R4, and R5 connected in series), resistors R7 and R8, voltage divider resistors R6, R9, and R10, capacitors C2 and C3, and comparator U1A.

[0031] The anodes of diodes D7, D8, and D9 are connected to the output terminals of the input power supply unit to sample the output voltage of the input power supply unit. The leads of diodes D7, D8, and D9 connected together are connected to the voltage divider resistor R1. The connection point of the circuit after connecting the cathodes of diodes D7, D8, and D9 is shown in the figure. Figure 2 The node labeled 6 (as shown) is used to connect to an external oscilloscope to obtain the connection point ( Figure 2 The voltage waveform diagram of node 6 is shown in Figure 6. The other end of the voltage divider resistor R1 is connected in series with R3, R4, and R5. The other end of the voltage divider resistor R5 is connected to resistor R7. The other end of resistor R7 is connected to capacitor C2 and the inverting input of comparator U1A. The voltage divider resistor R6 is connected in parallel across the connection line between resistor R7 and capacitor C2. The non-inverting input of comparator U1A is connected to voltage divider resistors R9 and R10. The other end of voltage divider resistor R9 is grounded, and the other end of R10 is connected to power supply VCC. The output of comparator U1A is connected to resistor R8. The other end of resistor R8 is connected to capacitor C3, and the other end of capacitor C3 is grounded. A connection point is taken on the connection line between resistor R8 and capacitor C3 (the point is shown in Figure 6). Figure 2As shown by reference numeral 15 "Node 15", it is used to connect to an external oscilloscope to obtain the waveform of the output comparison signal of comparator U1A; resistor R7 and capacitor C2, and resistor R8 and capacitor C3 respectively form a first-order low-pass filter, which is used to filter out signal noise in the circuit. In this circuit, diodes D7, D8, and D9 are model 1N4007-E3 / 54; comparator U1A is model LM2903DG.

[0032] In this embodiment, the input power supply unit uses a 380V three-phase voltage input, with a waveform of a sine wave with a 120° phase difference between the three phases. The peak line voltage is 537.32V. When the input voltage is normal, such as Figure 3 As shown, the voltage fluctuation at node 6 of the phase loss detection unit is relatively small. The voltage waveform at this point detected by the oscilloscope is shown in the figure below. Figure 3 As shown in the diagram. When a phase is missing from the input, the voltage at node 6 of the phase loss detection unit fluctuates significantly. It determines whether a phase is missing by detecting the minimum value and comparing it with the preset value of comparator U1A. The voltage waveform at node 6 detected by the oscilloscope when a phase is missing is shown in the diagram. Figure 4 As shown.

[0033] The working principle of this embodiment is as follows: In a 380V three-phase input power supply system, the line voltage VL = 380V, the phase voltage Vphase = 220V, the maximum output bus voltage of the three-phase input uncontrolled rectifier unit is Ubus_max = 1.414*VL, Ubus_max = 537.32V, the minimum bus voltage is Ubus_min = 2.34*VL / 2, Ubus_min = 444.6V.

[0034] When one phase is lost, the maximum bus voltage remains unchanged at Ubus_max = 537.32V. However, due to the loss of one phase, two sets of line voltages are missing within one cycle, leaving only one set of line voltage, i.e., a sinusoidal voltage with a peak value of 380V, which has a zero-crossing point and a minimum value of zero. Considering voltage fluctuations, the comparison voltage Vp at the non-inverting input of comparator U1A is set to Vp = 5*R9 / (R10+R9), where the resistance of R9 can be 1K, the resistance of R10 can be 4.7K, Vp = 0.877V, the voltage divider resistors R1, R3, R4, and R5 are 470K, and R6 is 6.2K. The voltage at the inverting input of comparator U1A is Vn = Vbb*R6 / (R1+R3+R4+R5+R6), meaning that the voltage at node 6 of the phase loss detection unit is Vbb = 266V.

[0035] When the three-phase input voltage is normal and there is no phase loss, Ubus_min > threshold value 266V (i.e., Vbb). At this time, the comparison result of comparator U1A is Vn > Vp, and the output terminal of comparator U1A (i.e., at node 15) outputs a continuous low level. The output waveform of comparator U1A is shown in Figure 5 as follows. In this Figure 5 , Channel A (i.e., channel A) is the voltage waveform at node 6 in the phase-loss detection unit, and Channel B (i.e., channel B) is the waveform at the output terminal of comparator U1A. When there is a phase loss in the input, the minimum bus voltage Ubus_min < threshold value 266V, and the comparison result of comparator U1A is Vn < Vp. The output signal of comparator U1A (i.e., at node 15) is a square-wave waveform. The output waveform of comparator U1A is shown in Figure 6 as follows. In this technical solution, by detecting whether there is a high level in the output waveform of comparator U1A, it is used to judge whether there is a phase loss in the input. It has the advantages of simple circuit, low cost, high reliability, etc.

[0036] According to the disclosure and teaching of the above specification, those skilled in the art of the present utility model can also make changes and modifications to the above embodiments. Therefore, the present utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the utility model should also fall within the protection scope of the claims of the present utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.

Claims

1. A three-phase power input phase loss detection circuit, characterized in that, It includes an input power supply unit, an uncontrolled rectifier unit, and a phase loss detection unit; the input power supply unit is connected to the uncontrolled rectifier unit and the phase loss detection unit respectively, wherein the input power supply unit is configured to output voltage to the uncontrolled rectifier unit, the uncontrolled rectifier unit serves as the load terminal of the input power supply unit, and the phase loss detection unit is configured to detect the output voltage of the input power supply unit and output a comparison signal to an external control unit. The phase loss detection unit includes diodes D7, D8, and D9, a voltage divider resistor circuit, resistors R7 and R8, voltage divider resistors R6, R9, and R10, capacitors C2 and C3, and comparator U1A. The voltage divider resistor circuit is formed by connecting one or more voltage divider resistors in series. The anodes of diodes D7, D8, and D9 are connected to the output terminals of the input power supply unit to sample the output voltage of the input power supply unit. The leads of diodes D7, D8, and D9 connected together are connected to the voltage divider resistor circuit, and the connection point of the circuit after connecting the cathodes of diodes D7, D8, and D9 is used to connect to an external oscilloscope to obtain the voltage waveform at that connection point. The other end of the voltage divider resistor circuit is connected to resistor R7, and the other end of resistor R7 is connected to capacitor C2. The inverting input of comparator U1A is connected to the voltage divider resistor R6 in parallel across the connection line between resistor R7 and capacitor C2; the non-inverting input of comparator U1A is connected to voltage divider resistors R9 and R10 respectively, with the other end of voltage divider resistor R9 grounded and the other end of R10 connected to power supply VCC; the output of comparator U1A is connected to resistor R8, with the other end of resistor R8 connected to capacitor C3, and the other end of capacitor C3 grounded; a connection point is taken on the connection line between resistor R8 and capacitor C3 for connection to an external oscilloscope to obtain the waveform of the output comparison signal of comparator U1A; The resistor R7 and capacitor C2, and the resistor R8 and capacitor C3 respectively form a first-order low-pass filter, which is used to filter out signal noise in the circuit.

2. The three-phase power input phase loss detection circuit according to claim 1, characterized in that, The voltage divider resistor circuit is formed by four voltage divider resistors R1, R3, R4, and R5 connected in series. Voltage divider resistor R1 serves as the input terminal of the voltage divider resistor circuit and is connected to the circuit after the negative terminals of diodes D7, D8, and D9 are connected. Voltage divider resistor R5 serves as the output terminal of the voltage divider resistor circuit and is connected to resistor R7.

3. The three-phase power input phase loss detection circuit according to claim 1, characterized in that, The input power unit includes three-phase power input terminals V1, V2, and V3, and the three-phase power input terminals V1, V2, and V3 are respectively connected to the positive terminals of diodes D7, D8, and D9.

4. The three-phase power input phase loss detection circuit according to claim 3, characterized in that, Switches S1A, S1B, and S1C are respectively installed on the lines where the three-phase power input terminals V1, V2, and V3 are connected to the positive terminals of diodes D7, D8, and D9, respectively, to control the on / off state of the lines.

5. The three-phase power input phase loss detection circuit according to claim 3, characterized in that, The uncontrolled rectifier unit includes six high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A, a capacitor C1, and an equivalent resistor R2. The cathodes of the high-voltage rectifier diodes D3A, D1A, and D2A are connected together to form a common cathode group, and the anodes of the high-voltage rectifier diodes D4A, D6A, and D5A are connected together and grounded to form a common anode group. The anode of high-voltage rectifier diode D3A is connected to the cathode of D4A, and its lead is connected to the three-phase power input terminal V1. The anode of high-voltage rectifier diode D1A is connected to the cathode of D6A, and its lead is connected to the three-phase power input terminal V2. The anode of high-voltage rectifier diode D2A is connected to the cathode of D5A, and its lead is connected to the three-phase power input terminal V3. After the capacitor C1 is connected in parallel with the equivalent resistance R2, its two ends are connected in parallel to the cathode of the high-voltage rectifier diode D2A and the anode of D5A.

6. The three-phase power input phase loss detection circuit according to claim 5, characterized in that, The high-voltage rectifier diodes D1A, D2A, D3A, D4A, D5A, and D6A are model DF10S / 45.

7. The three-phase power input phase loss detection circuit according to claim 1, characterized in that, The diodes D7, D8, and D9 are model number 1N4007-E3 / 54.

8. The three-phase power input phase loss detection circuit according to claim 1, characterized in that, The comparator U1A is model LM2903DG.

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