Isolated power supply AC voltage acquisition circuit

Abstract

The utility model discloses an isolation power supply AC voltage acquisition circuit, comprising a resistance-capacitance isolation step-down circuit unit which uses a capacitor to isolate 220V power from a main control board and uses a resistor to divide the isolated power into millivolt AC voltage; and the differential amplification circuit unit filters and amplifies the millivolt-level alternating-current voltage signal by using an operational amplifier and sends the millivolt-level alternating-current voltage signal to a sampling end. According to the utility model, the resistance-capacitance isolation step-down circuit unit is arranged, a capacitance isolation mode is adopted, a special isolation circuit is not needed, the structure is simple, the anti-interference capability is strong, safety accidents are not easy to occur, and the isolation is safer; aC impedance is large and power consumption is small.

Description

Technical Field

[0001] The utility model relates to the technical field of isolated power supply voltage collection, in particular to an isolated power supply AC voltage collection circuit. Background Art

[0002] There are two main ways to sample AC in existing isolated power supplies. One is isolation through a transformer. The primary side of the transformer uses resistors to limit the current, and the secondary side uses resistors to divide the voltage, reducing the AC power to a small signal. The other is through resistors to divide the voltage, which usually needs to pass through a metering chip and also needs to be isolated by an optocoupler.

[0003] The cost of using a transformer for isolation is high, and if no transformer is used, communication isolation is required, which also requires high costs; building a current loop on L and N will result in a small voltage divider impedance and high power consumption. The present invention has a large AC impedance and low power consumption. At the same time, the cost of capacitor isolation using the present invention is reduced.

[0004] Patent document No. CN 217590583 U discloses an isolated power supply output sampling circuit, and the disclosed solution has the effect of enabling the isolated power supply to adjust the output voltage in time according to the consumption change of the load. However, it can be seen that it uses mutual inductor isolation, and the cost of the entire circuit is relatively high. Utility Model Content

[0005] The utility model aims to provide an isolated power supply AC voltage acquisition circuit, which adopts a capacitor isolation method, has a simple structure, low production cost, and can be better applied to isolated power supply sampling.

[0006] The purpose of the utility model can be achieved through the following technical solutions: an isolated power supply AC voltage acquisition circuit, comprising:

[0007] The RC isolation step-down circuit unit uses capacitors to isolate the 220V power from the main control board, and uses resistors to divide the isolated power into millivolt AC voltage;

[0008] The differential amplifier circuit unit uses an operational amplifier to filter and amplify the millivolt-level AC voltage signal and sends it to the sampling end.

[0009] Optionally, the RC isolation step-down circuit unit includes capacitors C1 and C2, and resistors R1, R4, R9 and R7;

[0010] Among them, one end of C1 is connected to the positive electrode of V1, and the other end is connected to one end of R4, the other end of R4 is connected to one end of R1 and the differential amplifier circuit unit, and the other end of R1 is grounded;

[0011] Among them, one end of C2 is connected to the negative electrode of V1, and the other end is connected to one end of R7, the other end of R7 is connected to one end of R9 and the differential amplifier circuit unit, and the other end of R9 is grounded.

[0012] Optionally, the differential amplifier circuit unit includes resistors R5, R8, R10 and R2 and an operational amplifier U1;

[0013] Among them, one end of R5 is connected to R1 and R4, the other end of R5 is connected to one end of R2 and the in-phase input end of U1, and the other end of R2 is grounded;

[0014] Among them, one end of R8 is connected to R7 and R9, the other end of R8 is connected to one end of R10 and the inverting input end of U1, and the other end of R10 is connected to the output end of U1;

[0015] The positive power supply terminal of U1 is connected to the VCC power supply, the negative power supply terminal of U1 is grounded, and the output terminal of U1 is connected to the sampling terminal.

[0016] Optionally, it further includes a voltage regulating circuit unit, wherein the voltage regulating circuit unit includes resistors R3 and R6;

[0017] Among them, one end of R6 is connected to the output end of U1, the other end of R6 is connected to one end of R3 and the sampling end, and the other end of R3 is connected to the 3V3 power supply.

[0018] Optionally, it further includes a follower circuit unit, wherein the follower circuit unit includes a voltage follower U2;

[0019] Among them, the non-inverting input terminal of U2 is connected to R3 and R6 or the output terminal of U1, the inverting input terminal of U2 is connected to the output terminal of U2, the positive power supply terminal of U2 is connected to the VCC power supply, the negative power supply terminal of U2 is grounded, and the output terminal of U2 is connected to the sampling terminal.

[0020] Optionally, the RC isolation step-down circuit unit, the differential amplifier circuit unit and the follower circuit unit are all connected to an oscilloscope.

[0021] Beneficial effects of the utility model:

[0022] 1. The utility model sets a resistor-capacitor isolation step-down circuit unit and adopts a capacitor isolation method, which does not require a special isolation circuit, has a simple structure, strong anti-interference ability, is not prone to safety accidents, and has safer isolation; the AC impedance is large and the power consumption is small.

[0023] 2. The utility model sets a voltage regulating circuit unit and a follower circuit unit, and the output voltage is an AC voltage, which can pull the signal up to between 0 and 3.3V; U2 is a voltage follower, which increases the input impedance, reduces the output impedance, is isolated from the subsequent circuit, protects the subsequent circuit, and can perform better sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural schematic diagram of an isolated power supply AC voltage acquisition circuit of the utility model;

[0025] Figure 2This is another structural schematic diagram of an isolated power supply AC voltage acquisition circuit of the utility model;

[0026] Figure 3 This is another structural schematic diagram of an isolated power supply AC voltage acquisition circuit of the utility model. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0028] like Figure 1-3 As shown, the utility model discloses an isolated power supply AC voltage acquisition circuit, including.

[0029] Embodiment 1: Figure 1 As shown:

[0030] An isolated power supply AC voltage collection circuit, comprising: a resistor-capacitor isolation step-down circuit unit, which uses a capacitor to isolate 220V electricity from a main control board, and uses a resistor to divide the isolated electricity into a millivolt AC voltage;

[0031] The differential amplifier circuit unit uses an operational amplifier to filter and amplify the millivolt-level AC voltage signal and sends it to the sampling end.

[0032] The RC isolation step-down circuit unit includes capacitors C1 and C2, and resistors R1, R4, R9 and R7;

[0033] Among them, one end of C1 is connected to the positive electrode of V1, and the other end is connected to one end of R4, the other end of R4 is connected to one end of R1 and the differential amplifier circuit unit, and the other end of R1 is grounded;

[0034] Among them, one end of C2 is connected to the negative electrode of V1 and one end of the switch S1, and the other end is connected to one end of R7. The other end of R7 is connected to one end of R9 and the differential amplifier circuit unit. The other end of R9 is grounded, and the other end of S1 is grounded.

[0035] The differential amplifier circuit unit includes resistors R5, R8, R10 and R2 and an operational amplifier U1;

[0036] Among them, one end of R5 is connected to R1 and R4, the other end of R5 is connected to one end of R2 and the in-phase input end of U1, and the other end of R2 is grounded;

[0037] Among them, one end of R8 is connected to R7 and R9, the other end of R8 is connected to one end of R10 and the inverting input end of U1, and the other end of R10 is connected to the output end of U1;

[0038] The positive power supply terminal of U1 is connected to the VCC power supply, the negative power supply terminal of U1 is grounded, and the output terminal of U1 is connected to the sampling terminal.

[0039] The RC isolation and voltage step-down circuit unit formed by C1, C2, R1, R4, R9 and R7 plays the role of RC isolation and voltage step-down. C1 and C2 isolate the 220V AC power from the main control board, and R1, R4, R9 and R7 divide the 220V AC power into millivolt AC voltage.

[0040] Embodiment 2: Figure 2 As shown:

[0041] On the basis of the first embodiment, a voltage regulating circuit unit is connected, the voltage regulating circuit unit includes resistors R3 and R6; wherein one end of R6 is connected to the output end of U1, the other end of R6 is connected to one end of R3 and the sampling end, and the other end of R3 is connected to a 3V3 power supply.

[0042] By connecting the voltage regulating circuit unit, R3 can pull up the signal at the output end of U1 to between 0 and 3V3, so that the AC voltage signal at the output end of U1 can be better detected.

[0043] Embodiment 3: Figure 3 As shown:

[0044] On the basis of Embodiment 1 or Embodiment 2, a follower circuit unit is connected, and the follower circuit unit includes a voltage follower U2; the in-phase input terminal of U2 is connected to one end of the intersection of R3 and R6, or connected to the output terminal of U1, the inverting input terminal of U2 is connected to the output terminal of U2, the positive power supply terminal of U2 is connected to the VCC power supply, the negative power supply terminal of U2 is grounded, and the output terminal of U2 is connected to the sampling terminal.

[0045] The follower circuit unit can increase the input impedance and reduce the output impedance, and can be isolated from the subsequent circuit to protect the subsequent circuit. It can also be deleted under low-cost control. The output end can be connected to the ADC sampling port of the microcontroller.

[0046] Further, such as Figure 1-3 As shown, the power supply V1 is connected to an oscilloscope XSC1, the RC isolation step-down circuit unit is connected to an oscilloscope XSC2, the differential amplifier circuit unit is connected to an oscilloscope XSC3, and the follower circuit unit is connected to an oscilloscope XSC4.

[0047] By observing with an oscilloscope, you can better view the changes in the voltage waveform, which is conducive to sampling.

[0048] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes according to the technical scheme and concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0049] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. An isolated power supply AC voltage acquisition circuit, characterized in that: include: The RC isolation step-down circuit unit uses capacitors to isolate the 220V power from the main control board, and uses resistors to divide the isolated power into millivolt AC voltage; The differential amplifier circuit unit uses an operational amplifier to filter and amplify the millivolt-level AC voltage signal and sends it to the sampling end.

2. The isolated power supply AC voltage acquisition circuit according to claim 1, characterized in that: The RC isolation step-down circuit unit includes capacitors C1 and C2, and resistors R1, R4, R9 and R7; Among them, one end of C1 is connected to the positive electrode of V1, and the other end is connected to one end of R4, the other end of R4 is connected to one end of R1 and the differential amplifier circuit unit, and the other end of R1 is grounded; Among them, one end of C2 is connected to the negative electrode of V1, and the other end is connected to one end of R7, the other end of R7 is connected to one end of R9 and the differential amplifier circuit unit, and the other end of R9 is grounded.

3. The isolated power supply AC voltage acquisition circuit according to claim 2, characterized in that: The differential amplifier circuit unit includes resistors R5, R8, R10 and R2 and an operational amplifier U1; Among them, one end of R5 is connected to R1 and R4, the other end of R5 is connected to one end of R2 and the in-phase input end of U1, and the other end of R2 is grounded; Among them, one end of R8 is connected to R7 and R9, the other end of R8 is connected to one end of R10 and the inverting input end of U1, and the other end of R10 is connected to the output end of U1; The positive power supply terminal of U1 is connected to the VCC power supply, the negative power supply terminal of U1 is grounded, and the output terminal of U1 is connected to the sampling terminal.

4. The isolated power supply AC voltage acquisition circuit according to claim 3, characterized in that: It also includes a voltage regulating circuit unit, and the voltage regulating circuit unit includes resistors R3 and R6; Among them, one end of R6 is connected to the output end of U1, the other end of R6 is connected to one end of R3 and the sampling end, and the other end of R3 is connected to the 3V3 power supply.

5. The isolated power supply AC voltage acquisition circuit according to claim 3 or 4, characterized in that: It also includes a follower circuit unit, wherein the follower circuit unit includes a voltage follower U2; Among them, the non-inverting input terminal of U2 is connected to R3 and R6 or the output terminal of U1, the inverting input terminal of U2 is connected to the output terminal of U2, the positive power supply terminal of U2 is connected to the VCC power supply, the negative power supply terminal of U2 is grounded, and the output terminal of U2 is connected to the sampling terminal.

6. The isolated power supply AC voltage acquisition circuit according to claim 5, characterized in that: The RC isolation step-down circuit unit, the differential amplifier circuit unit and the follower circuit unit are all connected to an oscilloscope.

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