Three-phase voltage, frequency and phase sequence detection circuit

Abstract

The utility model discloses a three-phase voltage, frequency and phase sequence detection circuit, and belongs to the technical field of electric power detection. The three-phase voltage, frequency and phase sequence detection circuit comprises an MCU control unit, an A-phase detection circuit, a B-phase detection circuit and a C-phase detection circuit, wherein the A-phase detection circuit, the B-phase detection circuit and the C-phase detection circuit have the same structure. Each detection circuit comprises a voltage sampling circuit and a frequency detection circuit. According to the utility model, the operational amplifier is used for scaling down the input voltage, and the input voltage is skillfully raised to a range which can be accurately sampled by the MCU, compared with a traditional transformer detection method, the size and the weight are greatly reduced, the waveform distortion is extremely small, the characteristics of an original voltage signal are accurately reflected, and the detection precision is greatly improved. The effects of small size, light weight, low cost and high detection precision can be simultaneously achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a three -phase voltage, frequency and phase sequence detection circuit belongs to electric power detection technical field. BACKGROUND

[0002] In recent years, with the rapid development of power technology and the continuous improvement of people's requirements for power stability and safety, dual power conversion system as an important power guarantee equipment, its application is increasingly widespread. The system can quickly switch to standby power supply when the main power supply fails, ensuring the continuity of power supply, which is crucial for maintaining the normal operation of critical equipment. However, with the continuous expansion and deepening of application fields, the performance requirements of dual power conversion system are becoming increasingly strict, especially in terms of voltage, phase, frequency and other key parameters of the power supply, users expect to obtain more accurate and reliable detection results.

[0003] The existing dual power conversion system product usually adopts transformer for voltage measurement, and then measures the voltage after voltage reduction. However, this measurement method has many shortcomings. On the one hand, the transformer itself has certain energy loss and voltage fluctuation, which will affect the accuracy of the measurement result. On the other hand, the voltage waveform after voltage reduction may be distorted, resulting in deviation between the measurement result and the actual situation. These problems not only affect the performance of the dual power conversion system, but also limit its promotion and application in high-precision and high-reliability application fields. Therefore, it is necessary to improve and innovate the existing dual power conversion system detection technology to meet the needs of users for high-quality power guarantee. INVENTION CONTENTS

[0004] In order to solve the above problems, the utility model provides a kind of three -phase voltage, frequency and phase sequence detection circuit, the circuit includes MCU control unit and the same structure A-phase detection circuit, B-phase detection circuit, C-phase detection circuit, each detection circuit includes: voltage sampling circuit and frequency detection circuit;

[0005] In the A-phase detection circuit, the voltage sampling circuit includes resistors R1, resistors R2, resistors R3, resistors R4 and operational amplifier U1A, the voltage to be measured is connected to the negative input terminal of the operational amplifier U1A through the resistor R1;The reference voltage is connected to the positive input terminal of the operational amplifier U1A through the resistor R3 and the resistor R2 in turn, and is connected to the N-phase;The resistor R4 is connected between the negative input terminal and the output terminal of the operational amplifier U1A;

[0006] The frequency detection circuit comprises a resistor R6 and an operational amplifier U1B, the positive input end of the operational amplifier U1B is connected with the output end of the operational amplifier U1A, and the negative input end is connected with a reference voltage; the resistor R6 is connected between the positive input end and the output end of the operational amplifier U1B;

[0007] The ADC (analog-to-digital conversion) pin of the MCU control unit is connected with the voltage sampling circuits Ua, Ub and Uc of the three-phase A, B and C respectively; the interrupt pin of the MCU is connected with the output ends PHASE_A, PHASE_B and PHASE_C of the frequency detection circuit.

[0008] In an embodiment, the positive input end of the operational amplifier U1B is connected with the output end of the operational amplifier U1A through a resistor R5.

[0009] In an embodiment, the resistance values of the resistor R1 and the resistor R2 are equal, and the resistance values of the resistor R3 and the resistor R4 are equal.

[0010] In an embodiment, the sampling voltage output by the voltage sampling circuit is:

[0011] U a = -R3 / R1*U AN +V ref

[0012] In which, U AN represents the voltage to be measured, and V ref represents a reference voltage.

[0013] In an embodiment, the B-phase detection circuit comprises a B-phase voltage sampling circuit and a B-phase frequency detection circuit.

[0014] The B-phase voltage sampling circuit comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14 and an operational amplifier U2A, the voltage to be sampled is connected with the negative input end of the operational amplifier U2A through the resistor R11; the reference voltage is connected with the positive input end of the operational amplifier U2A through the resistor R13 and the resistor R12 in sequence and is connected with the N-phase; the resistor R14 is connected between the negative input end and the output end of the operational amplifier U2A;

[0015] The B-phase frequency detection circuit comprises a resistor R16 and an operational amplifier U2B, the positive input end of the operational amplifier U2B is connected with the output end of the operational amplifier U2A, and the negative input end is connected with a reference voltage; the resistor R16 is connected between the positive input end and the output end of the operational amplifier U1B.

[0016] In an embodiment, the resistance R11 and the resistance R12 have the same resistance value, and the resistance R13 and the resistance R14 have the same resistance value.

[0017] In an embodiment, the C-phase detection circuit comprises a C-phase voltage sampling circuit and a C-phase frequency detection circuit.

[0018] The C-phase voltage sampling circuit comprises a resistance R21, a resistance R22, a resistance R23, a resistance R24 and an operational amplifier U3A, the voltage to be detected is connected to the negative input terminal of the operational amplifier U3A through the resistance R21; a reference voltage is connected to the positive input terminal of the operational amplifier U3A through the resistance R23 and the resistance R22 in sequence, and is connected to the N-phase; the resistance R24 is connected between the negative input terminal and the output terminal of the operational amplifier U3A.

[0019] The C-phase frequency detection circuit comprises a resistance R26 and an operational amplifier U3B, the positive input terminal of the operational amplifier U3B is connected to the output terminal of the operational amplifier U3A, and the negative input terminal is connected to a reference voltage; the resistance R26 is connected between the positive input terminal and the output terminal of the operational amplifier U3B.

[0020] In an embodiment, the resistance R21 and the resistance R22 have the same resistance value, and the resistance R23 and the resistance R24 have the same resistance value.

[0021] The utility model discloses the advantages are:

[0022] The utility model discloses the advantages are:

[0023] More importantly, the detection circuit of the utility model can accurately restore the voltage waveform, ensure that the waveform distortion is very small when processing the voltage signal, accurately reflect the characteristics of the original voltage signal, and this characteristic makes the utility model have obvious advantages in occasions requiring high-precision voltage detection.

[0024] In conclusion, the utility model discloses the advantages are: BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1The utility model discloses three -phase voltage, frequency and phase sequence detection circuit structure diagram for dual power change over switch of the utility model embodiment 1.

[0026] Figure 2 The utility model discloses the connection drawing of MCU and sampling circuit in the utility model embodiment 1. Specific implementation

[0027] The following is to carry out specific description to the utility model.

[0028] Embodiment 1:

[0029] As Figure 1 Shown, it is three -phase voltage, frequency and phase sequence detection circuit structure diagram for dual power change over switch of the utility model, including: A phase voltage sampling circuit, A phase frequency detection circuit, B phase voltage sampling circuit, B phase frequency detection circuit, C phase voltage sampling circuit, C phase frequency detection circuit.

[0030] As Figure 1 Shown, A phase voltage sampling circuit includes resistance R1, R2, R3, R4 and operational amplifier U1A, in this embodiment, for the convenience of calculation, set R1=R2, R3=R4, then A phase sampling voltage U a =-R3 / R1*U AN +V ref , wherein U AN Indicate A phase voltage.

[0031] A phase frequency detection circuit includes resistance R5, R6 and operational amplifier U1B, U1B and R6 constitute comparison circuit, compare A phase sampling voltage U a With reference voltage V ref , and output square wave PHASE_A, when U a Greater than V ref , when U a Less than V ref , output low level, and the frequency of square wave PHASE_A is detected by MCU, namely A phase frequency.

[0032] B phase voltage sampling circuit includes resistance R11, R12, R13, R14 and operational amplifier U2A, in this embodiment, for the convenience of calculation, set R11=R12, R13=R14, then B phase sampling voltage U b =-R13 / R11*U BN +V ref , wherein U BN Indicate B phase voltage.

[0033] B phase frequency detection circuit includes resistance R15, R16 and operational amplifier U2B, U2B and R16 constitute comparison circuit, compare B phase sampling voltage U band the reference voltage V ref is compared, and a square wave PHASE_B is outputted, when U b is greater than V ref , a high level is outputted, when U b is less than V ref , a low level is outputted, and the MCU detects the frequency of the square wave PHASE_B to obtain the B phase frequency.

[0034] The C phase voltage sampling circuit comprises resistors R21, R22, R23 and R24 and an operational amplifier U3A, in the embodiment, for the convenience of calculation, R21=R22, R23=R24 are set, then the C phase sampling voltage U c =-R23 / R21*U CN +V ref , wherein U CN represents the C phase voltage.

[0035] The C phase frequency detection circuit comprises resistors R25 and R26 and an operational amplifier U3B, U3B and R26 constitute a comparison circuit, the C phase sampling voltage U c is compared with the reference voltage V ref , and a square wave PHASE_C is outputted, when U c is greater than V ref , a high level is outputted, when U c is less than V ref , a low level is outputted, and the MCU detects the frequency of the square wave PHASE_C to obtain the C phase frequency.

[0036] The MCU detects the ADC sampling of U a , U b and U c to accurately obtain the voltages of the A, B and C three phases; the MCU detects the frequency of the square wave PHASE_A to obtain the A phase frequency, detects the frequency of the square wave PHASE_B to obtain the B phase frequency, and detects the frequency of the square wave PHASE_C to obtain the C phase frequency, and detects the timing of PHASE_A, PHASE_B and PHASE_C to obtain the phase sequence of the A, B and C.

[0037] Although the utility model has disclosed as above with preferred embodiments, it is not used to limit the utility model, anyone familiar with the technology can make various changes and modifications without departing from the spirit and scope of the utility model, therefore the protection scope of the utility model should be defined by the claims.

Claims

1. A three-phase voltage, frequency and phase sequence detection circuit, characterized by, The circuit comprises an MCU control unit and A-phase detection circuit, B-phase detection circuit and C-phase detection circuit which are of the same structure, each detection circuit comprising a voltage sampling circuit and a frequency detection circuit; In the A-phase detection circuit, the voltage sampling circuit comprises resistors R1, R2, R3, R4 and an operational amplifier U1A, the voltage to be measured is connected to the negative input terminal of the operational amplifier U1A through the resistor R1; a reference voltage is connected to the positive input terminal of the operational amplifier U1A through the resistor R3 and the N-phase in turn through the resistor R3 and resistor R2; and the resistor R4 is connected between the negative input terminal and the output terminal of the operational amplifier U1A; The frequency detection circuit comprises a resistor R6 and an operational amplifier U1B, the positive input terminal of the operational amplifier U1B is connected to the output terminal of the operational amplifier U1A, and the negative input terminal is connected to a reference voltage; and the resistor R6 is connected between the positive input terminal and the output terminal of the operational amplifier U1B. The ADC pin of the MCU control unit is connected to the output terminals Ua, Ub and Uc of the voltage sampling circuits of the A-phase, B-phase and C-phase respectively; and the interrupt pin of the MCU is connected to the output terminals PHASE_A, PHASE_B and PHASE_C of the frequency detection circuits.

2. The three-phase voltage, frequency and phase sequence detection circuit of claim 1, wherein, The positive input terminal of the operational amplifier U1B is connected to the output terminal of the operational amplifier U1A through the resistor R5.

3. The three-phase voltage, frequency and phase sequence detection circuit of claim 1, wherein, The resistors R1 and R2 have the same resistance value, and the resistors R3 and R4 have the same resistance value.

4. The three-phase voltage, frequency and phase sequence detection circuit of claim 3, wherein, The sampling voltage output by the voltage sampling circuit is: U a = -R3 / R1*U AN +V ref wherein U AN represents the voltage to be sampled, V ref represents the reference voltage.

5. The three-phase voltage, frequency, and phase sequence detection circuit of claim 1, wherein, The B-phase detection circuit comprises a B-phase voltage sampling circuit and a B-phase frequency detection circuit; The B-phase voltage sampling circuit comprises resistors R11, R12, R13, R14 and an operational amplifier U2A, the voltage to be measured is connected to the negative input terminal of the operational amplifier U2A through the resistor R11; a reference voltage is connected to the positive input terminal of the operational amplifier U2A through the resistor R13 and the N-phase in turn through the resistor R13 and resistor R12; and the resistor R14 is connected between the negative input terminal and the output terminal of the operational amplifier U2A; The B-phase frequency detection circuit comprises a resistor R16 and an operational amplifier U2B, the positive input terminal of the operational amplifier U2B is connected to the output terminal of the operational amplifier U2A, and the negative input terminal is connected to a reference voltage; and the resistor R16 is connected between the positive input terminal and the output terminal of the operational amplifier U1B.

6. The three-phase voltage, frequency, and phase sequence detection circuit of claim 5, wherein, The resistors R11 and R12 have the same resistance value, and the resistors R13 and R14 have the same resistance value.

7. The three-phase voltage, frequency, and phase sequence detection circuit of claim 1, wherein, The C-phase detection circuit comprises a C-phase voltage sampling circuit and a C-phase frequency detection circuit; The C-phase voltage sampling circuit comprises resistors R21, R22, R23, R24 and an operational amplifier U3A, the voltage to be measured is connected to the negative input terminal of the operational amplifier U3A through the resistor R21; a reference voltage is connected to the positive input terminal of the operational amplifier U3A through the resistor R23 and then through the resistor R22 to the N-phase; and the resistor R24 is connected between the negative input terminal and the output terminal of the operational amplifier U3A. The C-phase frequency detection circuit comprises a resistor R26 and an operational amplifier U3B, the positive input terminal of the operational amplifier U3B is connected to the output terminal of the operational amplifier U3A, and the negative input terminal is connected to a reference voltage; and the resistor R26 is connected between the positive input terminal and the output terminal of the operational amplifier U3B.

8. The three-phase voltage, frequency, and phase sequence detection circuit of claim 7, wherein, The resistors R21 and R22 have the same resistance value, and the resistors R23 and R24 have the same resistance value.

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