DC voltage detection circuit based on optocoupler isolation

Abstract

The utility model discloses a direct-current voltage detection circuit based on optocoupler isolation. A traditional voltage division circuit is simple in structure and low in cost, but is low in sampling precision and resolution ratio, and needs a precisely matched resistor, which is often difficult to realize in practical application. The circuit comprises an input circuit, a protection circuit and an optical coupler isolation circuit, the output end of the input circuit is connected with the input end of the protection circuit, and the output end of the protection circuit is connected with the input end of the optical coupler isolation circuit. And an output signal of the optocoupler isolation circuit passes through the phase inverter and then is used as output of direct-current voltage sampling. The direct-current voltage detection device is used for direct-current voltage detection of optocoupler isolation.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of voltage detection technical field in device, especially about a kind of direct current voltage detection circuit based on photo-coupler isolation. BACKGROUND

[0002] In the industrial control field, it is essential to accurately sample the direct current voltage of a device or a component. Although the traditional voltage dividing circuit is simple in structure and low in cost, its sampling accuracy and resolution are low, and it requires precisely matched resistors, which is often difficult to achieve in practical applications. In addition, due to the special requirements for personnel and equipment safety, reliability, and stable operation, using an isolated detection method to sample the direct current voltage is a more reasonable and safe choice. Although this method increases the sampling cost and may have a slower response speed due to the use of optical isolation devices, it can effectively improve the reliability of equipment operation. SUMMARY

[0003] The utility model aims to make up for the shortcomings of the prior art and provides a direct current voltage detection circuit based on photo-coupler isolation.

[0004] The above-mentioned purpose is achieved by the following technical solutions:

[0005] A direct current voltage detection circuit based on photo-coupler isolation, which comprises an input circuit, a protection circuit, and a photo-coupler isolation circuit. The output end of the input circuit is connected to the input end of the protection circuit, the output end of the protection circuit is connected to the input end of the photo-coupler isolation circuit, and the output signal of the photo-coupler isolation circuit is sent to the output of the direct current voltage sampling after passing through an inverter.

[0006] The input circuit of the direct current voltage detection circuit based on photo-coupler isolation comprises a third diode, which is connected to the negative pole of the direct current input end, with its anode connected to the fourth resistor.

[0007] One pin of the second resistor is connected to the positive pole of the input voltage, and the other end is connected to the cathode of the voltage stabilizing diode and one end of the third resistor. The other end of the third resistor is connected to the second resistor and the fourth resistor, and it is also the output end of the input circuit.

[0008] The protection circuit of the direct current voltage detection circuit based on photo-coupler isolation comprises a voltage stabilizing diode, a second diode, and a second capacitor. The anode of the voltage stabilizing diode is connected to the cathode of the second diode, and the cathode is connected to the connection point of the third resistor and the second resistor. The anode of the second diode is connected to the common connection point of the third resistor and the fourth resistor of the input circuit.

[0009] The second capacitor and the second diode are connected in parallel and are connected as the output of the protection circuit and the optical coupling isolation circuit.

[0010] The optical coupling isolation circuit comprises an isolation optical coupling, a first resistor and a first capacitor.

[0011] The first pin of the isolation optical coupling is connected with the anode of the voltage stabilizing diode, the second pin is connected with GND, the fourth pin is connected with the first resistor, and the third pin is connected with digital ground.

[0012] The inverter is connected with the first resistor; the first resistor R1 is connected with a 5V power supply, and the first capacitor is connected with 5V. Advantages

[0013] 1. The utility model discloses a device for converting a direct current voltage signal into a digital analog signal by using an optical coupling and an inverter, for voltage detection, improving the operation reliability of the equipment, and by optimizing the circuit design, the slow response speed of the optical isolation device can be compensated to some extent, faster and more accurate voltage sampling is realized, and the performance and efficiency of the industrial control system are improved while ensuring safety.

[0014] 2. The third diode D3 of the utility model is placed for voltage reverse connection, and when the input direct current voltage is connected correctly, the third diode is normally turned on, the voltage dividing circuit normally works, and has a certain protection effect.

[0015] 3. The second capacitor C2 and the second diode D2 of the utility model are connected in parallel and are connected as the output of the protection circuit and the optical coupling isolation circuit; the voltage stabilizing diode D1 works in reverse breakdown when the reverse voltage reaches a specified value, the second diode D2 plays a role in protecting the optical coupling in the optical coupling isolation circuit; and the second capacitor C2 is mainly used for filtering and then outputting a voltage signal to the optical coupling.

[0016] 4. The optical coupling isolation circuit of the utility model pulls up the output of the optical coupling side through the first resistor R1, when the isolation optical coupling does not have a conduction signal, the high level of the first resistor R1 side is output as low level 0 through the inverter, when the isolation optical coupling is turned on, the fourth pin of the isolation optical coupling is pulled down, and the low level is changed into high level output 1 through the inverter. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are provided to further illustrate the utility model. Figure 1 It is the schematic diagram of the utility model.

[0018] In the drawings: W, input circuit; X, protection circuit; Y, optical coupling isolation circuit; Z, inverter. DETAILED DESCRIPTION

[0019] Reference is made to Figure 1A direct current voltage detection circuit based on optical coupling isolation, which consists of input circuit W, protection circuit X and optical coupling isolation circuit Y, the output of the input circuit is connected with the input of the protection circuit, the output of the protection circuit is connected with the input of the optical coupling isolation circuit, and the output signal of the optical coupling isolation circuit is connected with the output of the direct current voltage sampling after the inverter Z.

[0020] The input circuit comprises a third diode D3, a second resistor R2, a third resistor R3 and a fourth resistor R4, the third diode is connected to the negative pole of the direct current input, and the anode thereof is connected with the fourth resistor R4.

[0021] One pin of the second resistor R2 is connected with the positive pole of the input voltage, the other end is connected with the cathode of the voltage stabilizing diode D1 and one end of the third resistor R3, and the other end of the third resistor R3 is connected with the fourth resistor R4, which is also the output of the input circuit.

[0022] The third diode D3 is used to prevent voltage reverse connection, when the positive and negative poles of the input direct current voltage are correctly connected, the diode is normally turned on, the voltage dividing circuit works normally, and has a certain protection effect.

[0023] The direct current input is selected as 200VDC for implementation verification.

[0024] The protection circuit comprises a voltage stabilizing diode D1, a second diode D2 and a second capacitor C2, the anode of the voltage stabilizing diode D1 is connected with the cathode of the second diode D2, the cathode is connected with the connection point of the third resistor R3 and the second resistor R2, and the anode of the second diode D2 is connected with the common connection point of the third resistor R3 and the fourth resistor R4 of the input circuit.

[0025] The second capacitor C2 and the second diode D2 are connected in parallel and are also connected with the output of the protection circuit and the optical coupling isolation circuit.

[0026] The voltage stabilizing diode D1 works in reverse breakdown mode after the reverse voltage reaches the specified value, the second diode D2 protects the optical coupling in the optical coupling isolation circuit, and the second capacitor C2 is mainly used for filtering and then outputting the voltage signal to the optical coupling isolation.

[0027] The optical coupling isolation circuit comprises an isolation optical coupling UC2, a first resistor R1 and a first capacitor C1.

[0028] The first pin of the isolation optical coupling is connected with the anode of the voltage stabilizing diode D1, the second pin is connected with GND, the fourth pin is connected with the first resistor R1, and the third pin is connected with the digital ground.

[0029] The inverter is connected with the first resistor R1; the first resistor R1 is connected with a 5V power supply, and the first capacitor C1 is connected with the 5V power supply.

[0030] The optical coupling isolation circuit pulls up the output of the isolation optical coupling side through the first resistor R1; when the isolation optical coupling does not conduct a signal, the high level of the first resistor R1 side outputs a low level 0 through the inverter; when the isolation optical coupling is turned on, the fourth pin of the isolation optical coupling is pulled low, and the low level becomes a high level output 1 after passing through the inverter;

[0031] The isolation optical coupling selects a type TLP627-1, and the 5V power supply is electrically isolated.

[0032] The utility model discloses a direct current voltage detection circuit based on optical coupling isolation, and the direct current signal detection has remarkable effect, and the reliability of equipment work is improved.

Claims

1. A DC voltage detection circuit based on opto-coupler isolation, characterized by: Its composition includes: input circuit, protection circuit and optocoupler isolation circuit, the output of the input circuit is connected with the input of the protection circuit, the output of the protection circuit is connected with the input of the optocoupler isolation circuit, the output signal of the optocoupler isolation circuit is connected with the input of the inverter and then as the output of DC voltage sampling.

2. The DC voltage detection circuit based on optical coupling isolation according to claim 1, characterized in that: The input circuit includes a third diode, the third diode is connected to the negative pole of the DC input, and the anode is connected with the fourth resistor; One pin of the second resistor is connected to the positive pole of the input voltage, the other end is connected to the cathode of the voltage stabilizing diode and one end of the third resistor; one end of the third resistor is connected with the second resistor, and the other end is connected with the fourth resistor, which is also the output of the input circuit.

3. The DC voltage detection circuit based on optical coupling isolation according to claim 2, characterized in that: The protection circuit includes a voltage stabilizing diode, a second diode and a second capacitor, the anode of the voltage stabilizing diode is connected with the cathode of the second diode, the cathode is connected with the connection point of the third resistor and the second resistor, and the anode of the second diode is connected with the common connection point of the third resistor and the fourth resistor of the input circuit; The second capacitor and the second diode are connected in parallel and also as the output of the protection circuit and the optocoupler isolation circuit.

4. The DC voltage detection circuit based on optical coupling isolation according to claim 3, characterized in that: The optocoupler isolation circuit includes an isolation optocoupler, a first resistor and a first capacitor; The first pin of the isolation optocoupler is connected with the anode of the voltage stabilizing diode, the second pin is connected with GND, the fourth pin is connected with the first resistor, and the third pin is connected with the digital ground; The inverter is connected with the first resistor; the first resistor R1 is connected with the 5V power supply, and the first capacitor is connected with the 5V power supply.

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