Device for isolated measurement of voltage and current input

Abstract

The utility model discloses a device for isolated measurement of voltage and current input, which belongs to the technical field of current and voltage measurement, and comprises an isolation module, a voltage measurement module, a current measurement module, a control module and an analog-to-digital converter module, the isolation module is respectively connected with the control module and the analog-to-digital converter module, and the analog-to-digital converter module is connected with the isolation module. The voltage measurement module and the current measurement module are respectively connected with the analog-to-digital converter module, and the analog-to-digital converter module comprises a measurement chip U1. According to the utility model, through the isolation module, when current signals and voltage signals are measured, field side signals are electrically isolated from the system, so that the reliability and the stability of the system are improved.

Description

Technical Field

[0001] This utility model relates to the field of voltage and current measurement, and specifically to a device for isolating and measuring voltage and current inputs. Background Technology

[0002] In a DCS (Distributed Control System), it is necessary to measure the input current and voltage.

[0003] In existing technologies, such as CN203745523U, a fast conversion device for acquiring voltage signals on a DCS control system is disclosed. This device includes a field measuring element, a DCS system input card connected to the field measuring element for signal acquisition, and a signal acquisition instrument. The fast conversion device is connected to the connection line between the field measuring element and the DCS system input card. The output of this fast conversion device is connected to the signal acquisition instrument, converting the 4-20mA current signal from the field measuring element into a 1-5V voltage signal before outputting it to the signal acquisition instrument. This solution uses raw data input signals, has a fast refresh rate, data delay of no more than 1 second, does not require defining the output point range, and bypasses the DCS system processor, enabling rapid reflection of changes in measurement data and reducing potential failure points.

[0004] While this solution can acquire current signals, it cannot isolate the field signal side from the system side, resulting in low anti-interference capability. Furthermore, it cannot effectively protect the circuit when encountering surge impacts. Utility Model Content

[0005] This invention aims to solve the aforementioned problems in the prior art by proposing a device for isolating the measurement of voltage and current inputs. This device achieves isolation between the field signal side and the system side, reduces interference, improves the stability of the DCS system, and effectively protects the circuit.

[0006] To achieve the above-mentioned objectives, the technical solution of this utility model is as follows:

[0007] A device for isolating and measuring voltage and current inputs, characterized in that it comprises: an isolation module, a voltage measurement module, a current measurement module, a control module, and an analog-to-digital converter module, wherein the isolation module is connected to the control module and the analog-to-digital converter module respectively, the voltage measurement module and the current measurement module are connected to the analog-to-digital converter module respectively, and the analog-to-digital converter module includes a measurement chip U1.

[0008] In one embodiment, the current measurement module includes a first transient voltage suppression diode TVS1, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a ninth capacitor C9; the fifth pin of the measurement chip U1 is connected to the sixth pin of the measurement chip U1 through the ninth capacitor C9; the fifth pin of the measurement chip U1 is connected to the current input terminal AI1-I through the ninth resistor R9, and the ninth resistor R9 is also grounded through the first transient voltage suppression diode TVS1, the tenth resistor R10, and the eleventh resistor R11 respectively.

[0009] In one embodiment, the voltage measurement module includes a second transient voltage suppression diode (TVS2), an operational amplifier U2, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a thirteenth capacitor C13; the seventh pin of the measurement chip U1 is connected to the eighth pin of the measurement chip U1 through the thirteenth capacitor C13; the seventh pin of the measurement chip U1 is connected to the output terminal of the operational amplifier U2 through the twelfth resistor R12; the output terminal of the operational amplifier U2 is connected to the inverting input terminal, and the non-inverting input terminal of the operational amplifier U2 is connected to the voltage input terminal AI1-V through the fourteenth resistor R14; the non-inverting input terminal of the operational amplifier U2 is also grounded through the second transient voltage suppression diode (TVS2).

[0010] In one embodiment, the isolation module includes a digital isolator U3, a fifteenth capacitor C15, and a sixteenth capacitor C16. Pins 11 to 14 of the digital isolator U3 are connected to pins 15, 3, 1, and 16 of the measurement chip U1, respectively. Pins 3 to 6 of the digital isolator U3 are connected to the control module. Pins 10 and 16 of the digital isolator U3 are connected to pins 15 and 9 of the digital isolator U3, respectively, through the fifteenth capacitor C15. Pins 7 and 1 of the digital isolator U3 are connected to pins 2 and 8 of the digital isolator U3, respectively, through the sixteenth capacitor C16.

[0011] Furthermore, in one embodiment, a voltage reference module is also included. The voltage reference module includes a voltage reference chip U4, a nineteenth capacitor C19, and a twentieth capacitor C20. The sixth and fifth pins of the voltage reference chip U4 are respectively connected to the ninth pin of the measurement chip U1, the second pin of the voltage reference chip U4 is grounded, and the fourth and third pins of the voltage reference chip U4 are respectively connected to the first voltage terminal AI1_5V. The fourth and third pins of the voltage reference chip U4 are grounded through the nineteenth capacitor C19, and the first pin of the voltage reference chip U4 is grounded through the twentieth capacitor C20.

[0012] Furthermore, in one embodiment, the voltage reference module further includes a seventeenth capacitor C17 and an eighteenth capacitor C18, and the ninth pin of the measurement chip U1 is connected to the tenth pin of the measurement chip U1 through the seventeenth capacitor C17 and the eighteenth capacitor C18, respectively.

[0013] Furthermore, in one embodiment, a tenth capacitor C10 and an eleventh capacitor C11 are also included, and the thirteenth and fourteenth pins of the measurement chip U1 are connected to the twelfth pin of the measurement chip U1 through the tenth capacitor C10 and the eleventh capacitor C11, respectively.

[0014] Furthermore, in one embodiment, a first magnetic bead FB1 is also included, and the thirteenth and fourteenth pins of the measurement chip U1 are respectively connected to the first voltage terminal AI1_5V through the first magnetic bead FB1.

[0015] The working principle of this utility model is as follows:

[0016] When a voltage-type analog signal is input, the analog signal is amplified and shaped by an operational amplifier and then fed to the ADC chip.

[0017] When a current-type analog signal is input, the current is converted into a voltage-type analog signal through resistors R10 / R11 and then fed to the ADC chip.

[0018] The voltage reference chip U4 provides the ADC chip with a reference voltage.

[0019] The ADC chip converts analog voltage or current signals into digital signals based on a reference voltage and transmits them to the isolation chip.

[0020] The isolation chip isolates the field side from the system side, preventing field-side interference from reaching the system and affecting system stability.

[0021] The isolated digital signal is transmitted to the control module, which then receives the analog-to-analog conversion value from the field acquisition terminal.

[0022] In summary, this utility model has the following advantages:

[0023] 1. This utility model achieves electrical isolation between the field-side signals and the system when measuring current and voltage signals through an isolation module, thereby improving the reliability and stability of the system;

[0024] 2. This utility model can effectively protect the circuit by using a transient suppression diode, reducing the impact of surge impact;

[0025] 3. This utility model can acquire voltage-type analog quantities or current-type analog quantities through wiring, unifying the two types of analog quantities into one AI acquisition module, simplifying product models and improving production efficiency. Attached Figure Description

[0026] Figure 1 This is a structural block diagram of a device for isolating and measuring voltage and current inputs according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a partial circuit structure of the device for isolating and measuring voltage and current inputs provided in this embodiment of the utility model;

[0028] Figure 3 This is a schematic diagram of the isolation module circuit structure provided in an embodiment of the present invention;

[0029] Figure 4 This is a partial circuit structure diagram of the voltage measurement module provided in this embodiment of the utility model;

[0030] Figure 5 This is a schematic diagram of the circuit structure of the voltage reference module provided in this embodiment of the utility model. Detailed Implementation

[0031] To more clearly illustrate this utility model, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the present invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of this utility model.

[0032] Example 1

[0033] This invention provides a device for isolating voltage and current measurement inputs, such as... Figure 1 As shown, it includes: an isolation module, a voltage measurement module, a current measurement module, a control module, and an ADC (Analog-to-Digital Converter) module. The isolation module is connected to both the control module and the ADC module, and the voltage measurement module and the current measurement module are connected to the ADC module.

[0034] The following is combined Figures 2-5 The various modules of this utility model will be described in detail.

[0035] like Figure 2 As shown, the ADC module includes a measurement chip U1, model number SC3794. The SC3794 is a low-power, low-noise, complete analog front-end for high-precision measurement applications. This chip integrates a low-noise 24-bit Σ-Δ ADC with three differential analog inputs and also integrates an on-chip low-noise instrumentation amplifier, allowing direct input of small signals. The SC3794 also integrates a reference voltage source, clock, and excitation current, greatly simplifying thermocouple system design.

[0036] The SC3794 exhibits a root mean square (RMS) noise of 52 nV at a gain of 64 and an update rate of 4.17 Hz. The device incorporates a precision, low-noise, low-drift internal bandgap reference voltage source, with the option of using an external differential reference voltage. Other features include a programmable drive current source, fuse current control, and a bias voltage generator. The bias voltage generator allows setting the common-mode voltage of a channel to AVDD / 2.

[0037] The SC3794 can operate using either an internal or external clock, and its output data rate can be programmed via software, varying from 4.17Hz to 940Hz. Furthermore, the SC3794 features a shutdown option; in shutdown mode, the entire ADC and its auxiliary functions are disabled, reducing the device's maximum power consumption to 1μA.

[0038] like Figure 2 As shown, the current measurement module includes a first transient voltage suppression diode (TVS1), a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, and a ninth capacitor C9. The fifth pin of the measurement chip U1 is connected to the sixth pin 6 of the measurement chip U1 via the ninth capacitor C9. The fifth pin of the measurement chip U1 is connected to the analog current AI1-I via the ninth resistor R9. The ninth resistor R9 is also grounded via the first transient voltage suppression diode TVS1, the tenth resistor R10, and the eleventh resistor R11. In this embodiment, TVS1 is of type SMF33CA, the ninth resistor R9 is of type 1.5K / 1%, the tenth resistor R10 is of type 100R / 0.1%, the eleventh resistor R11 is of type 100R / 0.1% / NC, and the ninth capacitor C9 is of type 470pF / 50V.

[0039] In this embodiment, the current input is 4-20mA, and the voltage at TP3 is 0.4-2V. TP3 is the test point, and TP3 represents the signal after the current is converted into voltage.

[0040] like Figure 2 , Figure 4As shown, the voltage measurement module includes a second transient voltage suppression diode (TVS2), an operational amplifier U2, a twelfth resistor (R12), a thirteenth resistor (R13), a fourteenth resistor (R14), and a thirteenth capacitor (C13). Pin 7 of the measurement chip U1 is connected to pin 8 of the measurement chip U1 through the thirteenth capacitor (C13). Pin 7 of the measurement chip U1 is connected to the output terminal of the operational amplifier U2 through the twelfth resistor (R12). The output terminal of the operational amplifier U2 is connected to the inverting input terminal. The non-inverting input terminal of the operational amplifier U2 is connected to the analog voltage AI1-V through the fourteenth resistor (R14). The non-inverting input terminal of the operational amplifier U2 is also grounded through the second transient voltage suppression diode (TVS2). In this embodiment, TVS2 is model SMF15CA, operational amplifier U2 is model SGM8251XN5G / TR, twelfth resistor R12 is model 30K / 0.1%, thirteenth resistor R13 is model 7.5K / 0.1%, fourteenth resistor R14 is model 1.5K / 1%, and thirteenth capacitor C13 is model 470pF / 50V.

[0041] In this embodiment, the voltage input is 0-10V, and the voltage at TP4 is 0-2V. The input filter for the voltage input terminals AI1-V is 1kHz. TP4 is the test point terminal, and TP4 represents the processed voltage signal.

[0042] like Figure 2 , Figure 3 As shown, the isolation module includes a digital isolator U3, a fifteenth capacitor C15, and a sixteenth capacitor C16. Pins 11 to 14 of the digital isolator U3 are connected to pins 15, 3, 1, and 16 of the measurement chip U1, respectively. Pins 3 to 6 of the digital isolator U3 are connected to the control module. Pins 10 and 16 of the digital isolator U3 are connected to pins 15 and 9 of the digital isolator U3, respectively, through capacitor C15. Pins 7 and 1 of the digital isolator U3 are connected to pins 2 and 8 of the digital isolator U3, respectively, through capacitor C16. In this embodiment, U3 is model 141M31, and capacitors C15 and C16 are 100nF / 50V.

[0043] Example 2

[0044] As a preferred embodiment of this utility model, based on embodiment 1, a device for isolating and measuring voltage and current inputs further includes a voltage reference module, such as... Figure 2 , Figure 5As shown, the voltage reference module includes a voltage reference chip U4, a nineteenth capacitor C19, and a twentieth capacitor C20. Pins 6 and 5 of the voltage reference chip U4 are connected to pin 9 of the measurement chip U1, pin 2 of the voltage reference chip U4 is grounded, pins 4 and 3 of the voltage reference chip U4 are connected to the first voltage terminal AI1_5V, pins 4 and 3 of the voltage reference chip U4 are grounded through the nineteenth capacitor C19, and pin 1 of the voltage reference chip U4 is grounded through the twentieth capacitor C20. In this embodiment, U4 is model CLREF0625BT, and the nineteenth capacitor C19 and the twentieth capacitor C20 are 100nF / 50V.

[0045] Example 3

[0046] As a preferred embodiment of this utility model, based on embodiment 2, such as Figure 2 As shown, the voltage reference module further includes a seventeenth capacitor C17 and an eighteenth capacitor C18. The ninth pin of the measurement chip U1 is connected to the tenth pin of the measurement chip U1 through the seventeenth capacitor C17 and the eighteenth capacitor C18, respectively. In this embodiment, the seventeenth capacitor C17 is 1uF / 50V, and the eighteenth capacitor C18 is 100nF / 50V.

[0047] Example 4

[0048] As a preferred embodiment of this utility model, such as Figure 2 As shown, based on Embodiment 1, a device for isolating and measuring voltage and current inputs further includes a tenth capacitor C10 and an eleventh capacitor C11. Pins thirteen and fourteen of the measuring chip U1 are connected to pin twelfth of the measuring chip U1 via the tenth capacitor C10 and the eleventh capacitor C11, respectively. In this embodiment, the tenth capacitor C10 is 10uF / 10V, and the eleventh capacitor C11 is 100nF / 50V.

[0049] Example 5

[0050] As a preferred embodiment of this utility model, based on embodiment 1, such as Figure 2 As shown, a device for isolating and measuring voltage and current inputs also includes a first magnetic bead FB1. The thirteenth and fourteenth pins of the measuring chip U1 are connected to the first voltage terminal AI1_5V through the first magnetic bead FB1.

[0051] The working principle of this utility model:

[0052] When a voltage-type analog signal is input, the analog signal is amplified and shaped by an operational amplifier and then fed to the ADC chip.

[0053] When a current-type analog signal is input, the current is converted into a voltage-type analog signal through resistors R10 / R11 and then fed to the ADC chip.

[0054] The voltage reference chip U4 provides the ADC chip with a reference voltage.

[0055] The ADC chip converts analog voltage or current signals into digital signals based on a reference voltage and transmits them to the isolation chip.

[0056] The isolation chip isolates the field side from the system side, preventing field-side interference from reaching the system and affecting system stability.

[0057] The isolated digital signal is transmitted to the control module, which then receives the analog-to-analog conversion value from the field acquisition terminal.

[0058] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A device for isolating and measuring voltage and current input, characterized in that: include: An isolation module, a voltage measurement module, a current measurement module, a control module and an analog-to-digital converter module. The isolation module is connected to the control module and the analog-to-digital converter module respectively. The voltage measurement module and the current measurement module are connected to the analog-to-digital converter module respectively. The analog-to-digital converter module includes a measurement chip U1.

2. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: The current measurement module includes a first transient voltage suppression diode TVS1, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a ninth capacitor C9; the fifth pin of the measuring chip U1 is connected to the sixth pin of the measuring chip U1 through the ninth capacitor C9; the fifth pin of the measuring chip U1 is connected to the current input terminal AI1-I through the ninth resistor R9, and the ninth resistor R9 is also grounded through the first transient voltage suppression diode TVS1, the tenth resistor R10 and the eleventh resistor R11 respectively.

3. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: The voltage measurement module includes a second transient voltage suppression diode TVS2, an operational amplifier U2, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a thirteenth capacitor C13; the seventh pin of the measuring chip U1 is connected to the eighth pin of the measuring chip U1 through the thirteenth capacitor C13; the seventh pin of the measuring chip U1 is connected to the output end of the operational amplifier U2 through the twelfth resistor R12; the output end of the operational amplifier U2 is connected to the inverting input end, the non-inverting input end of the operational amplifier U2 is connected to the voltage input end AI1-V through the fourteenth resistor R14, and the non-inverting input end of the operational amplifier U2 is also grounded through the second transient voltage suppression diode TVS2.

4. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: The isolation module includes a digital isolator U3, a fifteenth capacitor C15 and a sixteenth capacitor C16, and the eleventh to fourteenth pins of the digital isolator U3 are respectively connected to the fifteenth pin, the third pin, the first pin and the sixteenth pin of the measurement chip U1; The third to sixth pins of the digital isolator U3 are respectively connected to the control module, and the tenth and sixteenth pins of the digital isolator U3 are respectively connected to the fifteenth and ninth pins of the digital isolator U3 through the fifteenth capacitor C15; The seventh pin and the first pin of the digital isolator U3 are connected to the second pin and the eighth pin of the digital isolator U3 respectively through the sixteenth capacitor C16.

5. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: It also includes a voltage reference module, which includes a voltage reference chip U4, a nineteenth capacitor C19 and a twentieth capacitor C20; the sixth pin and the fifth pin of the voltage reference chip U4 are respectively connected to the ninth pin of the measurement chip U1, the second pin of the voltage reference chip U4 is grounded, and the fourth pin and the third pin of the voltage reference chip U4 are respectively connected to the first voltage terminal AI1_5V; the fourth pin and the third pin of the voltage reference chip U4 are respectively grounded through the nineteenth capacitor C19, and the first pin of the voltage reference chip U4 is grounded through the twentieth capacitor C20.

6. The device for isolating and measuring voltage and current input according to claim 5, characterized in that: The voltage reference module further includes a seventeenth capacitor C17 and an eighteenth capacitor C18, and the ninth pin of the measuring chip U1 is connected to the tenth pin of the measuring chip U1 through the seventeenth capacitor C17 and the eighteenth capacitor C18 respectively.

7. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: It also includes a tenth capacitor C10 and an eleventh capacitor C11. The thirteenth and fourteenth pins of the measuring chip U1 are connected to the twelfth pin of the measuring chip U1 through the tenth capacitor C10 and the eleventh capacitor C11 respectively.

8. The device for isolating and measuring voltage and current input according to claim 1, characterized in that: It also includes a first magnetic bead FB1, and the thirteenth and fourteenth pins of the measuring chip U1 are respectively connected to the first voltage terminal AI1_5V through the first magnetic bead FB1.

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