Novel three-phase voltage isolation detection circuit

Abstract

The utility model relates to a novel three-phase voltage isolation detection circuit, which comprises a three-phase rectification network, a voltage division network, an isolation and linear amplification unit and a differential amplification unit, one end of the three-phase rectification network is connected with an AC three-phase power supply; the other end of the three-phase rectification network is connected with one end of the voltage division network; the other end of the voltage division network is connected with one end of the isolation and linear amplification unit; and the other end of the isolation and linear amplification unit is connected with the differential amplification unit. According to the novel three-phase voltage isolation detection circuit, voltage waveform detection and calculation can be carried out on three-phase alternating current at the same time through an ingenious current structure without using a voltage sensor, the three-phase alternating current is converted into an analog-digital signal which can be directly recognized and used by a processor, and the novel three-phase voltage isolation detection circuit has the advantages of being small in size, low in cost, high in reliability and the like. And the system can be widely applied to various industrial control and related electric control fields, and has objective practicability and economic characteristics.

Description

Technical Field

[0001] This utility model belongs to the field of fully automated products and relates to a novel three-phase voltage isolation detection circuit. Background Technology

[0002] In industrial control, it is often necessary to detect the voltage of three-phase AC power to provide data for calculation and control in subsequent circuits. For example, in control circuits of PFC power supplies and DC inverters, real-time acquisition and calculation of AC input voltage values ​​are required. When designing circuits and control boards, a unified circuit topology can be used for acquiring the voltage signals for this section.

[0003] When it is necessary to collect three-phase AC voltage, the following methods are often used:

[0004] 1. Voltage sensor;

[0005] 2. Voltage is collected by stepping down the AC voltage using a voltage divider resistor.

[0006] Both methods have their own advantages and disadvantages. Voltage sensor sampling isolation acquires AC voltage, often requiring three voltage sensors to collect data from every two phases when acquiring three-phase AC voltage. This is costly, bulky, and requires external control circuitry for signal acquisition and processing. Furthermore, voltage sensors typically have slow response times. Resistor voltage divider measurement, on the other hand, uses a non-isolated method. To reconstruct the complete three-phase voltage signal, three independent resistor divider networks may be needed. Because it's non-isolated, safety and other related issues must be considered in subsequent circuit design. Utility Model Content

[0007] To address the problem that in the industrial control field, voltage detection of three-phase AC power is widely used in the control of industrial frequency converters, industrial fans, inverters, and solar controllers, and that only voltage sensors can be used in situations requiring high-voltage isolation measurement, these sensors are costly, bulky, and often require the measurement of 2-3 phase-to-phase voltages to achieve complete waveform detection, and the output signal still needs to be filtered and converted by corresponding circuits before it can be used, the technical solution adopted by this utility model is: a novel three-phase voltage isolation detection circuit, including a three-phase rectifier network, a voltage divider network, an isolation and linear amplification unit, and a differential amplification unit;

[0008] One end of the three-phase rectifier network is electrically connected to one end of the three-phase AC power supply.

[0009] The other end of the three-phase rectifier network is electrically connected to one end of the voltage divider network;

[0010] The other end of the voltage divider network is electrically connected to one end of the isolation and linear amplification unit;

[0011] The other end of the isolation and linear amplification unit is electrically connected to the differential amplification unit.

[0012] Furthermore, the three-phase rectifier network includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6;

[0013] The cathode of the first diode D1 is connected to the cathode of the second diode D2 and the cathode of the third diode D3, and the anode of the first diode D1 is connected to phase A of the three-phase power supply and the cathode of the fourth diode D4.

[0014] The anode of the second diode D2 is connected to phase B of the three-phase power supply and the cathode of the fifth diode D5;

[0015] The anode of the fourth diode D4 is connected to the anode of the fifth diode D5 and the anode of the sixth diode D6.

[0016] The anode of the third diode D3 is connected to phase C of the three-phase power supply and the cathode of the sixth diode D6.

[0017] Furthermore, the voltage divider network includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a ninth resistor R9;

[0018] One end of the first resistor is connected to the cathode of the third diode D3. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected in series. The other end of the fourth resistor is connected to one end of the ninth resistor, and the other end of the ninth resistor is connected to the cathode of the sixth diode D6.

[0019] Furthermore, the isolation and linear differential amplification unit includes a fourth capacitor C4, a fifth capacitor C5, a tenth resistor R10, a linear optocoupler IC1, and a third capacitor;

[0020] One end of the fourth capacitor C4 and one end of the fifth capacitor C5 are both connected to the other end of the ninth resistor R9. The other end of the fourth capacitor C4 is connected to the other end of the fourth resistor R4 and the second pin of the linear optocoupler. The other end of the fifth capacitor C5 is connected to the +5V power supply and the first pin of the linear optocoupler IC1. The two ends of the tenth resistor are connected to the third and fourth pins of the linear optocoupler IC1, respectively. One end of the third capacitor is connected to the fifth pin of the linear optocoupler IC1 and ground. The other end of the third capacitor is connected to the +5V power supply.

[0021] Further: The differential amplifier unit includes a sixth resistor R6, a seventh resistor R7, a fifth resistor R5, a first capacitor C1, a second capacitor C2, an eighth resistor R8, a sixth capacitor C6, and an operational amplifier IC2A;

[0022] One end of the sixth resistor R6 is connected to pin 6 of the linear optocoupler IC1, and the other end of the sixth resistor R6 is connected to the positive input terminal of the operational amplifier IC2A, one end of the fifth resistor R5, and one end of the first capacitor C1. The other ends of the fifth resistor R5 and the first capacitor C1 are connected to ground. One end of the seventh resistor R7 is connected to pin 7 of the linear optocoupler, and the other end of the seventh resistor R7 is connected to the negative input terminal of the operational amplifier IC2A, one end of the eighth resistor R8, and one end of the sixth capacitor C6. The other ends of the eighth resistor R8 and the sixth capacitor C6 are connected to the negative output terminal of the operational amplifier IC2A.

[0023] The novel three-phase voltage isolation detection circuit provided by this utility model has the following advantages: The novel three-phase voltage isolation detection circuit mentioned in this invention can simultaneously detect and calculate the voltage waveform of three-phase AC power without using a voltage sensor and through a clever current structure, and convert it into an analog-to-digital signal that can be directly recognized and used by a processor. It has the characteristics of small size, low cost, and easy use, and can be widely used in various industrial control and related electrical control fields, with objective practicality and economic characteristics. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a module diagram of this application;

[0026] Figure 2 This is the circuit schematic diagram of this application;

[0027] Figure 3 This is a practical application of the present application. (a) is a signal detection diagram of the present application, and (b) is an equivalent substitution diagram of the present application.

[0028] Figure labels: 2. Three-phase rectifier network, 3. Voltage divider network, 4. Isolation and linear amplification unit, 5. Differential amplification unit. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Figure 1 This is a module diagram of this application;

[0032] A novel three-phase voltage isolation detection circuit includes a three-phase rectifier network 2, a voltage divider network 3, an isolation and linear amplification unit 4, and a differential amplification unit 5;

[0033] The input voltage signal is introduced into the three-phase rectifier network 2 through the terminals. The three-phase voltage signal is eliminated by the three-phase rectifier network 2 to form a three-phase superimposed positive half-axis combined waveform.

[0034] The voltage signal is then converted to a higher level by the voltage divider network 3, and then enters the isolation and linear differential amplifier unit 4. After being amplified by 8 times the voltage isolation, the corresponding three-phase voltage signal waveform is output. It then enters the differential amplifier unit 5, where the signal undergoes two-stage amplification. By proportionally distributing the resistance of other resistors to the differential input resistor, a 0-4V voltage signal with the same frequency and phase as the three-phase AC voltage source is obtained. This 0-4V voltage signal with the same frequency and phase as the three-phase AC voltage source is then transmitted to an analog-to-digital converter or a processor with similar functions for analysis and calculation.

[0035] Figure 2 This is the circuit schematic diagram of this application;

[0036] The three-phase rectifier network 2 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6;

[0037] The cathode of the first diode D1 is connected to the cathode of the second diode D2 and the cathode of the third diode D3, and the anode of the first diode D1 is connected to phase A of the three-phase power supply and the cathode of the fourth diode D4.

[0038] The anode of the second diode D2 is connected to phase B of the three-phase power supply and the cathode of the fifth diode D5;

[0039] The anode of the fourth diode D4 is connected to the anode of the fifth diode D5 and the anode of the sixth diode D6.

[0040] The anode of the third diode D3 is connected to phase C of the three-phase power supply and the cathode of the sixth diode D6.

[0041] The voltage divider network 3 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a ninth resistor R9;

[0042] One end of the first resistor is connected to the cathode of the third diode D3. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected in series. The other end of the fourth resistor is connected to one end of the ninth resistor, and the other end of the ninth resistor is connected to the cathode of the sixth diode D6.

[0043] The isolation and linear differential amplifier unit 4 includes a fourth capacitor C4, a fifth capacitor C5, a tenth resistor R10, a linear optocoupler IC1, and a third capacitor.

[0044] One end of the fourth capacitor C4 and one end of the fifth capacitor C5 are both connected to the other end of the ninth resistor R9. The other end of the fourth capacitor C4 is connected to the other end of the fourth resistor R4 and the second pin of the linear optocoupler. The other end of the fifth capacitor C5 is connected to the +5V power supply and the first pin of the linear optocoupler. The two ends of the tenth resistor are connected to the third and fourth pins of the linear optocoupler, respectively. One end of the third capacitor is connected to the fifth pin of the linear optocoupler and ground. The other end of the third capacitor is connected to the +5V power supply.

[0045] The differential amplifier unit 5 includes a sixth resistor R6, a seventh resistor R7, a fifth resistor R5, a first capacitor C1, a second capacitor C2, an eighth resistor R8, a sixth capacitor C6, and an operational amplifier IC2A.

[0046] One end of the sixth resistor R6 is connected to pin 6 of the linear optocoupler, and the other end of the sixth resistor R6 is connected to the positive input terminal of the operational amplifier IC2A, one end of the fifth resistor R5, and one end of the first capacitor C1. The other ends of the fifth resistor R5 and the first capacitor C1 are connected to ground. One end of the seventh resistor R7 is connected to pin 7 of the linear optocoupler, and the other end of the seventh resistor R7 is connected to the negative input terminal of the operational amplifier IC2A, one end of the eighth resistor R8, and one end of the sixth capacitor C6. The other ends of the eighth resistor R8 and the sixth capacitor C6 are connected to the negative output terminal of the operational amplifier IC2A.

[0047] Since the operating frequency of three-phase AC voltage used in industrial applications is 50 or 60 Hz, which falls into the low-frequency range, this circuit can not only detect low-frequency voltage signals but also, by modifying diodes D1, D2, D3, D4, D5, and D6 to be high-frequency diodes, detect and reconstruct high-frequency three-phase or other high-frequency voltage signals. The accuracy is generally within 0.5V, and it can completely reflect the waveform of the input voltage signal. Therefore, with the circuit structure designed above, the voltage amplitude and frequency characteristics corresponding to the three-phase AC voltage signal can be calculated. After secondary signal processing, the value is converted from analog to digital. This circuit achieves three-phase AC voltage detection in a safe, accurate, compact, and low-cost manner, and can be widely used in circuits or controllers in various industrial control fields.

[0048] In the fields of industrial frequency converters and industrial fan control, it is necessary to detect the amplitude and phase of the input three-phase voltage. Through the flexible use of this circuit, on the one hand, the amplitude of the three-phase voltage can be precisely detected, and on the other hand, the phase sequence and frequency of the three-phase voltage can be detected in real time. Currently, it has begun to be designed and used in industrial frequency converters of 3KW-20KW, and has achieved good control characteristics and economic benefits.

[0049] Figure 3 This is a practical application of the present application. (a) is a signal detection diagram of the present application, and (b) is an equivalent substitution diagram of the present application.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel three-phase voltage isolation detection circuit, characterized in that: It includes a three-phase rectifier network, a voltage divider network, an isolation and linear amplification unit, and a differential amplification unit; One end of the three-phase rectifier network is electrically connected to one end of the three-phase AC power supply. The other end of the three-phase rectifier network is electrically connected to one end of the voltage divider network; The other end of the voltage divider network is electrically connected to one end of the isolation and linear amplification unit; The other end of the isolation and linear amplification unit is electrically connected to the differential amplification unit.

2. The novel three-phase voltage isolation detection circuit according to claim 1, characterized in that: The three-phase rectifier network includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6; The cathode of the first diode D1 is connected to the cathode of the second diode D2 and the cathode of the third diode D3, and the anode of the first diode D1 is connected to phase A of the three-phase power supply and the cathode of the fourth diode D4. The anode of the second diode D2 is connected to phase B of the three-phase power supply and the cathode of the fifth diode D5; The anode of the fourth diode D4 is connected to the anode of the fifth diode D5 and the anode of the sixth diode D6. The anode of the third diode D3 is connected to phase C of the three-phase power supply and the cathode of the sixth diode D6.

3. The novel three-phase voltage isolation detection circuit according to claim 1, characterized in that: The voltage divider network includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a ninth resistor R9; One end of the first resistor is connected to the cathode of the third diode D3. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are connected in series. The other end of the fourth resistor is connected to one end of the ninth resistor, and the other end of the ninth resistor is connected to the cathode of the sixth diode D6.

4. The novel three-phase voltage isolation detection circuit according to claim 3, characterized in that: The isolation and linear differential amplifier unit includes a fourth capacitor C4, a fifth capacitor C5, a tenth resistor R10, a linear optocoupler IC1, and a third capacitor. One end of the fourth capacitor C4 and one end of the fifth capacitor C5 are both connected to the other end of the ninth resistor R9. The other end of the fourth capacitor C4 is connected to the other end of the fourth resistor R4 and the second pin of the linear optocoupler. The other end of the fifth capacitor C5 is connected to the +5V power supply and the first pin of the linear optocoupler IC1. The two ends of the tenth resistor are connected to the third and fourth pins of the linear optocoupler IC1, respectively. One end of the third capacitor is connected to the fifth pin of the linear optocoupler IC1 and ground. The other end of the third capacitor is connected to the +5V power supply.

5. The novel three-phase voltage isolation detection circuit according to claim 1, characterized in that: The differential amplifier unit includes a sixth resistor R6, a seventh resistor R7, a fifth resistor R5, a first capacitor C1, a second capacitor C2, an eighth resistor R8, a sixth capacitor C6, and an operational amplifier IC2A. One end of the sixth resistor R6 is connected to pin 6 of the linear optocoupler IC1, and the other end of the sixth resistor R6 is connected to the positive input terminal of the operational amplifier IC2A, one end of the fifth resistor R5, and one end of the first capacitor C1. The other ends of the fifth resistor R5 and the first capacitor C1 are connected to ground. One end of the seventh resistor R7 is connected to pin 7 of the linear optocoupler, and the other end of the seventh resistor R7 is connected to the negative input terminal of the operational amplifier IC2A, one end of the eighth resistor R8, and one end of the sixth capacitor C6. The other ends of the eighth resistor R8 and the sixth capacitor C6 are connected to the negative output terminal of the operational amplifier IC2A.

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