Voltage measuring circuit

Abstract

The utility model provides a voltage measuring circuit which is used for measuring the input voltage of a measured product, the circuit comprises an upper computer, a control panel, a measuring device and a power supply, and the power supply is connected to an ADC calibration port of the control panel for power supply; a first ADC acquisition module of the control board is connected with an ADC calibration port to acquire a first voltage of a power supply port; a second ADC acquisition module of the control board is connected with the input port of the tested product to acquire a second voltage of the input port; one end of the measuring device is connected with the ADC calibration port to acquire a third voltage, and the other end sends the third voltage to the upper computer; the control panel sends the first voltage and the second voltage to the upper computer through the communication interface; and the upper computer outputs calibration voltage of the input port of the tested product according to deviation values of the first voltage and the second voltage relative to the third voltage. According to the invention, the power input port and the power supply port of the product are combined for voltage compensation, the actual tripping voltage of the product can be accurately measured, and the stability and safety of a power system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a voltage measurement circuit. Background Art

[0002] In the field of power protection and control, the trip unit is a key component, and accurate measurement of its trip voltage is crucial to ensure the safe operation of the power system. Traditionally, the measurement of the trip voltage is mainly achieved by monitoring the voltage value at the power output port. This method can roughly reflect the trip voltage of the trip unit under ideal conditions. However, in actual applications, due to line losses in power transmission lines, impedance changes between contact points, and various other unforeseen environmental factors, the voltage value measured at the power output port often cannot accurately represent the voltage value actually received by the trip unit and triggers the trip operation.

[0003] This difference will not only affect the accuracy of the release performance evaluation, but may also lead to false operation or refusal to operate, thus endangering the stability and safety of the power system. Utility Model Content

[0004] In order to solve the above problems, the present application provides a voltage measurement circuit that can accurately measure the actual tripping voltage of the release, overcome the measurement errors caused by line loss and contact impedance, and improve the stability and safety of the power system.

[0005] In a first aspect, the present application provides 1. A voltage measurement circuit for measuring the input voltage of a product under test, the circuit comprising a host computer, a control board, a measuring device and a power supply, characterized in that the control board comprises a first ADC acquisition module and a second ADC acquisition module;

[0006] The power supply is connected to the ADC calibration port of the control board for power supply;

[0007] The first ADC acquisition module is connected to the ADC calibration port to acquire the first voltage of the power supply port;

[0008] The second ADC acquisition module is connected to the input port of the product under test and acquires the second voltage of the input port;

[0009] One end of the measuring device is connected to the ADC calibration port to collect the third voltage, and the other end of the measuring device is connected to the host computer to send the third voltage;

[0010] The control board sends the first voltage and the second voltage to the host computer through the communication interface;

[0011] The host computer is used to output a calibration voltage of the input port of the tested product according to a deviation value of the first voltage and the second voltage relative to the third voltage.

[0012] In a possible implementation manner, the first ADC acquisition module includes a plurality of first resistors and a first voltage follower U1A;

[0013] The positive input voltage of the power supply is input to the non-inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R79; the negative input voltage of the power supply is input to the inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R75; the output terminal of the first voltage follower U1A is connected to the communication interface of the control board through the first output resistor R77 to feed back the first voltage;

[0014] The second ADC acquisition module includes a plurality of second resistors and a second voltage follower U1B;

[0015] The positive input voltage provided by the control board is input into the non-inverting input terminal of the second voltage follower U1B through the second voltage-dividing resistor R81; the negative input voltage provided by the control board is input into the inverting input terminal of the second voltage follower U1B through the second voltage-dividing resistor R76; the output terminal of the second voltage follower U1B is connected to the communication interface of the control board through the second output resistor R78 to feed back the second voltage.

[0016] In a possible implementation manner, one end of the output resistor R77 is connected to the output end of the first voltage follower, and the other end is connected to the first clamping diode;

[0017] One end of the second output resistor R78 is connected to the output end of the second voltage follower, and the other end is connected to the second clamping diode.

[0018] In a possible implementation manner, the power input port of the control board is connected to a target voltage, and the target voltage is also used as a power supply voltage of the first voltage follower U1A and the second voltage follower U1B.

[0019] In a possible implementation manner, the invention further includes: a first switch and a first relay, a second switch and a second relay;

[0020] The first switch controls the conduction of the first relay. When the first relay is turned on, the first ADC acquisition module is powered on, collects the first voltage and feeds back the first voltage;

[0021] The second switch controls the conduction of the second relay. When the second relay is turned on, the second ADC acquisition module is powered on, collects the second voltage and feeds it back.

[0022] In a possible implementation manner, serial communication is used between the host computer and the control board and the power supply, and USB communication is used between the host computer and the measuring device.

[0023] In a possible implementation manner, the measuring device is a multimeter, and the multimeter measures the third voltage and feeds back the third voltage to the host computer through a USB interface.

[0024] In a possible implementation manner, the positive pole of the multimeter and the positive pole of the power supply are connected to the ADC calibration port together; the negative pole of the multimeter and the negative pole of the power supply are connected to the ADC calibration port together.

[0025] The technical solution provided by this application includes at least the following technical effects:

[0026] This application combines the product power input port and power supply port for voltage compensation, which can accurately measure the actual tripping voltage of the product, overcome the measurement errors caused by line loss and contact impedance, improve the pass rate of the test, reduce the cost of rework and repair, and improve the stability and safety of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 is a schematic diagram of a voltage measurement circuit provided in an embodiment of the present application;

[0029] Figure 2 is a circuit diagram of an ADC acquisition module provided in an embodiment of the present application;

[0030] Figure 3 is a circuit diagram of an ADC calibration port provided in an embodiment of the present application;

[0031] Figure 4 is a circuit diagram of a control switch provided in an embodiment of the present application;

[0032] Figure 5 is a driving circuit diagram of a product under test provided in an embodiment of the present application;

[0033] Figure 6 is a schematic diagram of another voltage measurement circuit provided in an embodiment of the present application.

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] To further illustrate the various embodiments, the present application provides drawings. These drawings are part of the disclosure of the present application, and are mainly used to illustrate the embodiments, and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and the advantages of the present application. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0036] The present application is now further described in conjunction with the accompanying drawings and specific implementation methods.

[0037] Example 1

[0038] An embodiment of the present application provides a voltage measurement circuit. Figure 1 Schematic diagram of a voltage measurement circuit provided by an embodiment of the present application. Figure 1 The technical solution of the embodiment of the present application is introduced.

[0039] The present application provides a voltage measurement circuit for measuring the input voltage of a product under test. Figure 1 As shown, in the circuit, the power supply supplies power to the control board, the first ADC acquisition module of the control board is connected to the power supply port to measure the first voltage, the second ADC acquisition module of the control board is connected to the product under test to measure the second voltage, and the measuring device is connected to the power supply port to measure the third voltage; the host computer communicates with the control board, the power supply and the measuring device respectively to control the power input and obtain the voltage data; the host computer compensates the voltage based on the obtained voltage data to obtain the calibrated voltage of the product under test.

[0040] The products under test are, for example, releases and related components in electrical equipment and protection devices. These products are usually used to automatically disconnect the circuit under specific voltage conditions to protect equipment and personal safety. For example, circuit breakers, contactors, contact switches, etc.

[0041] In the embodiment of the present application, the circuit includes a host computer, a control board, a measuring device and a power supply. The control board includes a first ADC acquisition module and a second ADC acquisition module.

[0042] The power supply is a direct current (DC) program-controlled power supply, which can change the output power supply parameters in response to program control instructions.

[0043] The host computer is used to control the power supply and the control board, and can read the circuit parameters measured by the control board and the measuring device, such as voltage and current. The host computer is, for example, a personal computer (PC), a workstation (WorkStation), a server (Server), a programmable logic controller (PLC), an embedded system and other computer devices.

[0044] In the embodiment of the present application, the power supply is connected to the ADC calibration port of the control board for power supply. The ADC calibration port provides a set of terminal interfaces connected to the ADC acquisition module. Exemplarily, the ADC calibration port is a terminal board or other forms of connectors and interfaces. For example, a pin connector, a socket connector, an edge connector, a flexible flat cable connector, etc. It can be selected according to the needs of the actual scenario.

[0045] In the embodiment of the present application, the control board is used to control the board to send the first voltage and the second voltage to the upper computer through the communication interface. Exemplarily, the control board is a micro control unit (MCU); it can also be a field programmable logic array (FPGA), an application specific integrated circuit (ASIC) and other control units, and the present application is not limited thereto.

[0046] The first ADC acquisition module is connected to the ADC calibration port to acquire a first voltage at the power supply port, and the second ADC acquisition module is connected to the input port of the product under test to acquire a second voltage at the input port.

[0047] Figure 2 : is a circuit diagram of an ADC acquisition module provided in an embodiment of the present application. Figure 2 The structure of ADC acquisition circuit is introduced.

[0048] In one possible implementation, the entire control board is powered by inputting a target voltage, and the control board accordingly powers two voltage followers. Specifically, the power input port of the control board is connected to the target voltage, and the target voltage is also used as the power supply voltage of the first voltage follower U1A and the second voltage follower U1B. Optionally, the target voltage is a 5V DC voltage (VCC_5V).

[0049] In a possible implementation, the first ADC acquisition module includes a plurality of first resistors and a first voltage follower U1A. Specifically, the positive input voltage of the power supply is input to the non-inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R79; the negative input voltage of the power supply is input to the inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R75; the output terminal of the first voltage follower U1A is connected to the communication interface of the control board through the first output resistor R77 to feed back the first voltage.

[0050] In a possible implementation, a clamping diode is used to protect the IO port of the MCU chip to avoid damage to the control chip in the event of an abnormality. Specifically, one end of the output resistor R77 is connected to the output end of the first voltage follower, and the other end is connected to the first clamping diode.

[0051] like Figure 2 As shown, the positive input voltage ADC0+ of the power supply is input to the in-phase input terminal 3 of the first voltage follower U1A through the first voltage divider resistor R79 with a resistance of 100K, and a 0 ohm jumper resistor R80 is connected in series between R79 and the in-phase input terminal 3; the negative input voltage ADC0- of the power supply is input to the inverting input terminal 2 of the first voltage follower U1A through another first voltage divider resistor R75 with a resistance of 10K. The output terminal 1 of the first voltage follower U1A is connected to the communication interface ADC_0 in the ADC calibration port of the control board through the first output resistor R77 with a resistance of 1K to feed back the first voltage to the control board. Figure 2 As shown, one end of ADC0- is grounded through a 0 ohm cross-border resistor R70; the power input terminal 8 of the first voltage follower U1A inputs the voltage of VCC_5V, and the power terminal 4 of U1A is grounded; the output end of U1A passes through the first output resistor R77 and is connected to a clamping diode, the positive electrode of the clamping diode is connected to the 3.3V VCC power supply, and the negative electrode is grounded.

[0052] In one possible implementation, the second ADC acquisition module includes a plurality of second resistors and a second voltage follower U1B. The positive input voltage provided by the control board is input into the in-phase input terminal of the second voltage follower U1B through the second voltage divider resistor R81; the negative input voltage provided by the control board is input into the inverting input terminal of the second voltage follower U1B through the second voltage divider resistor R76; the output terminal of the second voltage follower U1B is connected to the communication interface of the control board through the second output resistor R78 to feed back the second voltage. One end of the second output resistor R78 is connected to the output terminal of the second voltage follower, and the other end is connected to the second clamping diode.

[0053] like Figure 2 As shown, the positive input voltage ADC1+ provided by the control board is input to the in-phase input terminal 5 of the second voltage follower U1B through the second voltage divider resistor R81 with a resistance of 100K, and a 0-ohm jumper resistor R82 is connected in series between R81 and the in-phase input terminal 5; the negative input voltage ADC1- provided by the control board is input to the inverting input terminal 6 of the second voltage follower U1B through another second voltage divider resistor R76 with a resistance of 10K. The output terminal 7 of U1B is connected to the communication interface ADC_1 in the ADC calibration port of the control board through the second output resistor R78 with a resistance of 1K to feed back the second voltage to the control board. Figure 2As shown, ADC1- is grounded through a 0 ohm cross-border resistor R73; U1B's power input terminal 8 inputs a voltage of VCC_5V, and U1B's power terminal 4 is grounded; U1B's output terminal 7 passes through a second output resistor R78 and is connected to a clamping diode, with the positive electrode of the clamping diode connected to the 3.3V VCC power supply and the negative electrode connected to the ground. Figure 2 As shown, a 100nF filter capacitor C17 is used between the VCC_5V power input terminal and the ground to filter and smooth the DC voltage.

[0054] The embodiment of the present application adopts a voltage follower in the voltage measurement circuit to construct an ADC acquisition circuit. Based on the high input impedance and low output impedance characteristics of the voltage follower, it is possible to achieve impedance matching and signal isolation, improve acquisition accuracy, protect the ADC circuit, and simplify circuit design, thereby comprehensively improving the performance stability and reliability of the entire voltage measurement circuit.

[0055] Among them, one end of the measuring device is connected to the ADC calibration port to collect the third voltage, and the other end of the measuring device is connected to the host computer to send the third voltage. The measuring device is, for example, a multimeter, which can measure the power input voltage with high precision. The third voltage is used as the actual value of the power supply port for calibration. Figure 3 is a circuit diagram of an ADC calibration port provided in an embodiment of the present application, such as Figure 3 As shown, in the voltage measurement circuit, the ADC calibration port is recorded as P5, and P5 includes the positive input voltage port ADC0+ of the power supply, the negative input voltage port ADC0- of the power supply, the positive input voltage ADC1+ provided by the control board, and the negative input voltage ADC1- provided by the control board. Data exchange and voltage input can be completed through the ADC calibration port.

[0056] In a possible implementation, serial communication is used between the host computer and the control board and the power supply, and USB communication is used between the host computer and the measuring device, wherein the serial communication protocol is, for example, a 485 serial communication protocol.

[0057] In one possible implementation, the measuring device is a multimeter, which measures the third voltage and feeds it back to the host computer through a USB interface. Furthermore, the positive pole of the multimeter and the positive pole of the power supply are connected to the ADC calibration port; the negative pole of the multimeter and the negative pole of the power supply are connected to the ADC calibration port. Based on this, the multimeter can achieve high-precision measurement of the voltage at the power supply port. The third voltage is used as a high-precision measurement value to calibrate the first voltage and the second voltage.

[0058] In the embodiment of the present application, the host computer outputs the calibration voltage of the input port of the product under test according to the deviation value of the first voltage and the second voltage relative to the third voltage. Specifically, the host computer controls the power supply to output N voltage values ​​within a preset period, and then reads the third voltage and the first voltage value of the first ADC acquisition module and the second voltage of the second ADC acquisition module through a multimeter for comparison. By calculating the first mean of the first gain and the first offset between the third voltage and the first voltage, and the second mean of the second gain and the second offset between the third voltage and the second voltage under N voltage values. The first mean and the second mean are averaged to obtain the calibration gain and the calibration offset; finally, the calibration gain and the calibration offset are used to calibrate the latest measured second voltage, that is, the calibration voltage of the product under test can be obtained by adding the calibration offset to the result of multiplying the calibration gain and the second voltage.

[0059] In a possible implementation, the circuit further includes a first switch and a first relay, a second switch and a second relay. The first switch controls the conduction of the first relay. When the first relay is conducted, the first ADC acquisition module is powered on, the first voltage is collected and fed back; the second switch controls the conduction of the second relay. When the second relay is conducted, the second ADC acquisition module is powered on, the second voltage is collected and fed back. The use of switches can realize flexible control of different ADC acquisition modules, so that the corresponding module can be quickly turned on when voltage calibration is required.

[0060] Figure 4 is a circuit diagram of a control switch provided in an embodiment of the present application, such as Figure 4 As shown, the first switch K15 controls the conduction of the first relay. When the first relay is conducted, 5V is supplied to the first ADC acquisition module through PORT21 of the control board; the second switch K16 controls the conduction of the second relay. When the second relay is conducted, 5V is supplied to the second ADC acquisition module through PORT22 of the control board; wherein DC+ and DC- supply power to the first ADC acquisition module, and X-DC+ and X-DC- supply power to the second ADC acquisition module. By controlling the opening and closing of K15 and K16, the use of the two ADC acquisition modules can be controlled, and P4 can provide access to the power supply DC and the power supply X-DC.

[0061] Furthermore, a driving circuit diagram of a product under test is provided to illustrate the connection relationship between the above control board and the product under test. Figure 5 is a driving circuit diagram of a product under test provided in an embodiment of the present application, such as Figure 5As shown in the figure, the tested product P1 uses a single N-channel MOSFET to achieve current control; the output OUT of the gate driver U6 (model FAN3111C) is connected to the control pin (gate G) of the MOSFET to drive the MOSFET. The source (S) of the MOSFET is grounded, and the drain (D) is connected to P1. The power supply port VDD of U6 uses a 10V input; the input terminal IN is connected to the input port MCU-PORT of the control board through the resistor R62.

[0062] This application combines the power input port and the power supply port of the product for voltage compensation, and can accurately measure the actual trip voltage of the product, overcome the measurement error caused by line loss and contact impedance, improve the pass rate of the test, reduce the cost of rework and repair, and improve the stability and safety of the power system. Furthermore, the ADC acquisition module is constructed based on the voltage follower to improve the performance stability and reliability of the entire voltage measurement circuit.

[0063] Example 2

[0064] An embodiment of the present application provides another voltage measurement circuit. Figure 6 is a schematic diagram of another voltage measurement circuit provided in an embodiment of the present application.

[0065] The voltage measurement circuit provided in the present application is used to measure the input voltage of the product under test. The DC program-controlled source supplies power to the MCU control board, the first ADC acquisition module of the MCU control board is connected to the power supply port of the DC program-controlled source to measure the first voltage, the second ADC acquisition module of the MCU control board is connected to the product under test to measure the second voltage, and the multimeter is connected to the power supply port of the power supply to measure the third voltage. The PC is respectively connected to the MCU control board, the DC program-controlled source and the multimeter for communication, to control the power input and obtain the voltage data, and the PC performs voltage compensation based on the obtained voltage data to obtain the calibration voltage of the product under test.

[0066] like Figure 6 As shown, the DC program-controlled source is connected to the ADC calibration port P5 of the MCU control board for power supply. The multimeter is connected to the ADC calibration port P5 to collect the third voltage, and the other end of the multimeter is connected to the PC through the USB interface to send the third voltage. P5 includes the positive input voltage port ADC0+ of the power supply, the negative input voltage port ADC0- of the power supply, the positive input voltage ADC1+ provided by the control board, and the negative input voltage ADC1- provided by the control board. Data exchange and voltage input can be completed through the ADC calibration port. 485 serial port communication is used between the PC and the MCU control board and the power supply.

[0067] This application combines the product power input port and power supply port for voltage compensation, which can accurately measure the actual tripping voltage of the product, overcome the measurement errors caused by line loss and contact impedance, improve the pass rate of the test, reduce the cost of rework and repair, and improve the stability and safety of the power system.

[0068] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which this application belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0069] Within the principle, any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of this application. Although the present application is specifically shown and described in conjunction with the preferred embodiment, it should be understood by those skilled in the art that various changes can be made to the present application in form and detail without departing from the spirit and scope of the present application defined by the attached claims, and all of them are within the protection scope of this application.

Claims

1. A voltage measurement circuit for measuring the input voltage of a product under test, the circuit comprising a host computer, a control board, a measuring device and a power supply, characterized in that: The control board includes a first ADC acquisition module and a second ADC acquisition module; The power supply is connected to the ADC calibration port of the control board for power supply; The first ADC acquisition module is connected to the ADC calibration port to acquire the first voltage of the power supply port; The second ADC acquisition module is connected to the input port of the product under test and acquires the second voltage of the input port; One end of the measuring device is connected to the ADC calibration port to collect the third voltage, and the other end of the measuring device is connected to the host computer to send the third voltage; The control board sends the first voltage and the second voltage to the host computer through the communication interface; The host computer is used to output a calibration voltage of the input port of the tested product according to a deviation value of the first voltage and the second voltage relative to the third voltage.

2. The voltage measurement circuit according to claim 1, characterized in that: The first ADC acquisition module includes a plurality of first resistors and a first voltage follower U1A; The positive input voltage of the power supply is input to the non-inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R79; the negative input voltage of the power supply is input to the inverting input terminal of the first voltage follower U1A through the first voltage divider resistor R75; the output terminal of the first voltage follower U1A is connected to the communication interface of the control board through the first output resistor R77 to feed back the first voltage; The second ADC acquisition module includes a plurality of second resistors and a second voltage follower U1B; The positive input voltage provided by the control board is input into the non-inverting input terminal of the second voltage follower U1B through the second voltage-dividing resistor R81; the negative input voltage provided by the control board is input into the inverting input terminal of the second voltage follower U1B through the second voltage-dividing resistor R76; the output terminal of the second voltage follower U1B is connected to the communication interface of the control board through the second output resistor R78 to feed back the second voltage.

3. The voltage measurement circuit according to claim 2, characterized in that: One end of the output resistor R77 is connected to the output end of the first voltage follower, and the other end is connected to the first clamping diode; One end of the second output resistor R78 is connected to the output end of the second voltage follower, and the other end is connected to the second clamping diode.

4. The voltage measurement circuit according to claim 2, characterized in that: The power input port of the control board is connected to a target voltage, and the target voltage is also used as a power voltage of the first voltage follower U1A and the second voltage follower U1B.

5. The voltage measurement circuit according to claim 1, characterized in that: Also includes: a first switch and a first relay, a second switch and a second relay; The first switch controls the conduction of the first relay. When the first relay is turned on, the first ADC acquisition module is powered on, collects the first voltage and feeds back the first voltage; The second switch controls the conduction of the second relay. When the second relay is turned on, the second ADC acquisition module is powered on, collects the second voltage and feeds it back.

6. The voltage measurement circuit according to claim 1, characterized in that: Serial communication is adopted between the host computer and the control board and the power supply, and USB communication is adopted between the host computer and the measuring device.

7. The voltage measurement circuit according to any one of claims 1 to 6, characterized in that: The measuring device is a multimeter, which measures the third voltage and feeds back the third voltage to the host computer through a USB interface.

8. The voltage measurement circuit according to claim 7, characterized in that: The positive pole of the multimeter and the positive pole of the power supply are connected to the ADC calibration port together; the negative pole of the multimeter and the negative pole of the power supply are connected to the ADC calibration port together.

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