Multi-section measuring range type constant-voltage constant-current test circuit

Abstract

The utility model discloses a multi-section range type constant-voltage constant-current test circuit, which mainly solves the problem of high design cost of the existing single-section full-range constant-voltage constant-current test circuit. The circuit comprises a single-chip microcomputer control module, and a power supply module, a constant-voltage constant-current module, a power amplification module and a communication and external control module which are connected with the single-chip microcomputer control module. Through the design, the full range is designed into a multi-section range (voltage: 150V gear, 50V gear and 18V gear; according to the invention, the design precision of the maximum gear is the same as the design precision of the full-scale gear, and although other gears have the same resolution with the full-scale gear, the lower the gear is, the smaller the division value corresponding to each unit resolution is, so that the design precision is improved, and the design cost is reduced. Therefore, the method is suitable for popularization.

Description

Technical Field

[0001] The utility model belongs to the technical field of constant voltage and constant current test circuits, in particular to a multi-range constant voltage and constant current test circuit. Background Art

[0002] Most of the existing constant voltage and constant current technology solutions adopt a single-segment full-range method. Under the conditions of large range and limited DAC / ADC resolution of traditional solutions, when setting small voltage or small current, the accuracy is often difficult to meet the design requirements. In order to meet the design, it is necessary to increase the number of bits of DAC / ADC resolution to achieve it. High-resolution DAC / ADC is expensive, which undoubtedly increases the design cost. Utility Model Content

[0003] The utility model aims to provide a multi-range constant voltage and constant current test circuit, which mainly solves the problem of high design cost of the existing single-range full-range constant voltage and constant current test circuit.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0005] A multi-range constant voltage and constant current test circuit comprises a single-chip control module, and a power module, a constant voltage and constant current module, a power amplifier module, and a communication and external control module all connected to the single-chip control module; the single-chip control module controls and exchanges information with other functional modules to ensure coordinated operation between the modules and monitor the working status of each module in real time; the power module provides power to each module to ensure the normal operation of each functional module; the power amplifier module constantly adjusts the input voltage or current from the constant voltage and constant current module; the communication and external control module is used to control the single-chip control module through a host computer.

[0006] Furthermore, in the utility model, the constant voltage and constant current module includes a voltage gear switching circuit, a current gear switching circuit, a voltage feedback circuit and a constant voltage and constant current setting circuit, all of which are connected to the single-chip microcomputer control module; a current feedback circuit connected to the current gear switching circuit, a sum-and-difference operation circuit connected to the constant voltage and constant current setting circuit, a current readback circuit connected to the sum-and-difference operation circuit, and a voltage readback circuit connected to both the voltage feedback circuit and the sum-and-difference operation circuit; wherein the voltage feedback circuit is also connected to the voltage gear switching circuit.

[0007] Further, in the utility model, the voltage gear switching circuit includes an optocoupler isolation chip U206 whose first port is connected to the single-chip control module via a resistor R242, MOS tubes V203 and V204 whose two gates are connected to the two output ends of the optocoupler isolation chip U206, and resistors R220, R219, R222 and R221 whose two ends are connected in series to a +12V voltage and a -12V voltage, respectively; wherein the sources of the MOS tubes V203 and V204 are interconnected, the common ends of the resistors R220 and R219 are connected to the gate of the MOS tube V203, the common ends of R222 and R221 are connected to the gate of the MOS tube V204, and the common ends of R219 and R222 are connected to the source of the MOS tube V203; the drain of the MOS tube V203 and the drain of V204 are connected to the voltage feedback circuit via resistors R218 and R217, respectively.

[0008] Furthermore, in the utility model, the current gear switching circuit includes a transistor V202 whose base is connected to the single-chip control module via a resistor R206 and whose emitter is grounded, a MOS transistor V201 whose gate is connected to the collector of the transistor V202, a resistor R205 whose one end is connected to the collector of the transistor V202 and whose other end is connected to a 5V voltage, and a resistor R203 connected between the drain and source of the MOS transistor V201; wherein the source of the MOS transistor V201 is grounded, and the drain of the MOS transistor V201 is connected to the sum and difference operation circuit.

[0009] Further, in the utility model, the voltage feedback circuit includes a transistor V205 whose base is connected to the single-chip control module via a resistor R227 and whose emitter is grounded, a resistor R110 whose one end is connected to the port connected to the single-chip control module by the resistor R227 and whose other end is grounded, a switch K2 of model HFD3 / 12 whose 8th port is connected to the collector of the transistor V205, a diode D201 whose positive electrode is connected to the 8th port of the switch K2 and whose negative electrode is connected to the 1st port of the switch K2, a resistor R229 connected between the 6th and 7th ports of the switch K2, a resistor R228 connected between the 2nd and 3rd ports of the switch K2, a wiring port JP202 whose 1st and 3rd ports are respectively connected to the 5th and 4th ports of the switch K2, a wiring port JP201 whose 1st and 3rd ports are respectively connected to the 7th and 2nd ports of the switch K2, and after series connection, one end is connected to the 6th port of the switch K2 and the other end is grounded. Resistors R207, R209, R211, R213, and R215; an operational amplifier U202 whose non-inverting input terminal is connected to the common terminal of resistors R213 and R215, and resistors R208, R210, R211, R212, and R214 whose one end is connected in series to the third port of switch K2 and the other end is connected to the inverting input terminal of the operational amplifier U202; a resistor R216 connected between the inverting input terminal and the output terminal of the operational amplifier U202, and capacitors C204 and C205 respectively connected to the positive and negative power supply terminals of the operational amplifier U202 and grounded; wherein the common end of resistors R211 and R213 is connected to the other end of resistor R217 in the voltage gear switching circuit; the common end of resistors R212 and R214 is connected to the other end of resistor R218 in the voltage gear switching circuit; the output terminal of the operational amplifier U202 is connected to the voltage readback circuit.

[0010] Furthermore, in the utility model, the current feedback circuit includes an operational amplifier U201 whose inverting input terminal is connected to the drain of the MOS tube V201 in the current gear switching circuit via a resistor R202, a resistor R201 whose one end is connected to the non-inverting input terminal of the operational amplifier U201 and the other end is grounded, a resistor R204 and a capacitor C203 whose two ends are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U201, and capacitors C201 and C202 which are respectively connected to the positive and negative power supply terminals of the operational amplifier U201 and are grounded; wherein the output terminal of the operational amplifier U201 is connected to the sum and difference operation circuit.

[0011] Furthermore, in the utility model, the constant voltage and constant current setting circuit includes an operational amplifier U205A whose positive input terminal is connected to the single-chip control module via a resistor R239, an operational amplifier U204A whose positive input terminal is connected to the single-chip control module via a resistor R238, a capacitor C217 whose one end is connected to the positive input terminal of the operational amplifier U205A and the other end is grounded, a capacitor C216 whose one end is connected to the positive input terminal of the operational amplifier U204A and the other end is grounded, a capacitor C218 whose one end is connected to the positive power supply terminal of the operational amplifier U205A and the other end is grounded, and capacitors C204 and C215 which are respectively connected to the positive and negative power supply terminals of the operational amplifier U205A and grounded; wherein, the inverting input terminal of the operational amplifier U205A is connected to the output terminal, the inverting input terminal of the operational amplifier U204A is connected to the output terminal, and the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U204A are both connected to the sum and difference operation circuit.

[0012] Furthermore, in the present invention, the sum-difference operation circuit includes an operational amplifier U301A whose inverting input terminal is connected to the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U201 via a resistor R310 and a non-inverting input terminal via a resistor R311, respectively; a resistor R313 and a capacitor C310 connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U301A; capacitors C308 and C309 connected to the positive and negative power supply terminals of the operational amplifier U301A and grounded, respectively; an operational amplifier U301B whose non-inverting input terminal is connected to the output terminal of the operational amplifier U205A via a resistor R308; a capacitor C303 connected between the inverting input terminal and the output terminal of the operational amplifier U301B; and capacitors C303 connected in series to the operational amplifier U301B. Resistor R306 and capacitor C304 are connected between the inverting input and output ends of the operational amplifier U301B; resistor R304 having one end connected to the inverting input of the operational amplifier U301B and the other end grounded, resistor R305 having one end connected to the inverting input of the operational amplifier U301B and the other end connected to a -12V voltage, resistors R307 and R309 having one end connected to the non-inverting input of the operational amplifier U301B, and capacitor C306 connected to the other end of resistor R309; wherein the other end of capacitor C306 is connected to the other end of resistor R307 and then connected to a voltage readback circuit; the common end of resistor R311 connected to the operational amplifier U201 is connected to a current readback circuit; the output end of the operational amplifier U301A and the output end of the operational amplifier U301B are output to an external isolation circuit.

[0013] Further, in the present invention, the voltage readback circuit includes an analog switch chip U2 of model ADG419BRZ-REEL, a resistor R7 connected between the second port of the analog switch chip U2 and the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit, an operational amplifier U203A having an inverting input terminal connected to the first port of the analog switch chip U2, and a resistor R23 having one end connected to the inverting input terminal of the operational amplifier U203A and the other end connected to the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit. 5, a resistor R233 having one end connected to the non-inverting input terminal of the operational amplifier U203A and the other end connected to ground, a resistor R234 having one end connected to the non-inverting input terminal of the operational amplifier U203A and the other end connected to a 5V voltage, and two ends connected in parallel to a resistor R236 and a capacitor C211 connected to the inverting input terminal and the output terminal of the operational amplifier U203A, and a capacitor C213 having one end connected to the positive power supply terminal of the operational amplifier U203A and the other end connected to ground; wherein, the output terminal of the operational amplifier U203A is connected to the single-chip control module via a resistor R237.

[0014] Furthermore, in the present invention, the current readback circuit includes an operational amplifier U203B whose non-phase input terminal is connected to one end of a resistor R311 in a sum-difference operation circuit via a resistor R230, a resistor R231 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a capacitor C209 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a resistor R232 whose one end is connected to the output terminal of the operational amplifier U203B, and a capacitor C210 whose one end is connected to the other end of the resistor R232 and whose other end is grounded; wherein, the inverting input terminal of the operational amplifier U203B is connected to the output terminal; and the common end of the resistor R232 and the capacitor C210 is connected to the single-chip control module.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] The test circuit of the utility model is under the limited condition of certain DAC / ADC resolution (for example, in order to save costs, it is often necessary to use the DAC / ADC built into the microcontroller, but the resolution of the DAC / ADC built into most microcontrollers cannot meet the accuracy design requirements.), if the accuracy of the full-scale design cannot meet the design requirements in the small voltage and small current range, the full-scale is designed into multiple ranges (voltage: 150V gear, 50V gear, 18V gear; current: full-scale 40A gear, 4A gear). From the results, the maximum gear has the same design accuracy as the full-scale gear. Although the other gears have the same resolution as the full-scale gear, the lower the gear, the smaller the division value corresponding to each unit resolution, thereby improving the design accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a principle block diagram of the utility model.

[0018] Figure 2 This is a principle block diagram of the constant voltage and constant current module in the utility model.

[0019] Figure 3 for Figure 2 Schematic diagram of the medium voltage gear switching circuit and voltage feedback circuit.

[0020] Figure 4 for Figure 2 Schematic diagram of the current gear switching circuit and current feedback circuit.

[0021] Figure 5 for Figure 2 Schematic diagram of the constant voltage and constant current setting circuit and the sum and difference operation circuit.

[0022] Figure 6 for Figure 2 Schematic diagram of the medium voltage readback circuit.

[0023] Figure 7 for Figure 2 Schematic diagram of the current readback circuit.

[0024] Figure 8 The schematic diagram of the circuit of the system power supply in the power module in the embodiment of the utility model.

[0025] Fig. 9 The schematic diagram of the circuit of the fan power supply in the power module in the embodiment of the utility model is shown in FIG.

[0026] Fig.10 This is a circuit schematic diagram of the single-chip microcomputer control module in the embodiment of the utility model.

[0027] Fig.11 This is a circuit schematic diagram of the power amplifier module in the embodiment of the utility model.

[0028] Fig.12 This is a circuit schematic diagram of communication and external control in an embodiment of the utility model. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The present invention includes but is not limited to the following embodiments.

[0030] Example

[0031] like Figure 1As shown, the utility model discloses a multi-range constant voltage and constant current test circuit, including a single-chip microcomputer control module, and a power supply module, a constant voltage and constant current module, a power amplifier module and a communication and external control module connected to the single-chip microcomputer control module; the single-chip microcomputer control module controls and exchanges information with other functional modules to ensure coordinated operation between the modules and monitor the working status of each module in real time; the power supply module provides power to each module to ensure the normal operation of each functional module; the power amplifier module constantly adjusts the input voltage or current from the constant voltage and constant current module; the communication and external control module is used to control the single-chip microcomputer control module through a host computer.

[0032] In this embodiment, the power module includes a system power supply and a fan power supply; the system power supply is used to power each functional module, and the fan power supply is used to power the fan control circuit in the single-chip control module. This part adopts the existing circuit, and one implementation circuit is as follows Figure 8 , 9 shown.

[0033] In this embodiment, the single-chip control module is mainly composed of a single-chip minimum system, NTC temperature detection, isolated communication, fan control and other circuits. The single-chip minimum system serves as the core control unit, controls and exchanges information with other functional modules, ensures coordinated operation between modules, and monitors the working status of each module in real time. Fig.10 As shown, it is the circuit principle diagram of the single chip control module in this embodiment.

[0034] In this embodiment, the power amplifier module is composed of a linear amplifier circuit and a high-power MOS tube. The linear amplifier circuit is composed of an integrated operational amplifier to build a negative feedback loop. The output of the post-stage operational amplifier is connected to the MOS tube G level to drive the MOS tube switch, thereby achieving constant regulation of the input voltage or current. The module circuit adopts the existing technology, and one implementation circuit is as follows Fig.11 shown.

[0035] In this embodiment, the voltage feedback circuit and the current feedback circuit also serve as a voltage sampling circuit and a current sampling circuit, respectively. The voltage sampling circuit reduces the current voltage by a certain proportion through the form of resistor voltage division, and then sends it to the differential proportional amplifier circuit, forming a closed-loop negative feedback loop with the constant voltage module to control the constant voltage input of the power amplifier module. The current sampling circuit is a manganese copper resistor with a small nominal resistance and low temperature drift, which is connected in series with the high-power MOS tube of the power amplifier module. The manganese copper resistor will be used as a current sampling resistor. When the current sampling resistor is used, the potential at both ends of the sampling resistor is taken and sent to the differential proportional amplifier circuit, forming a closed-loop negative feedback loop with the constant current module to control the constant current input of the power amplifier module. Through the IO output of the single-chip microcomputer, the amplification factor of the differential proportional amplifier circuit is controlled and adjusted, and multiple gears are set to achieve the purpose of switching the voltage or current gear.

[0036] In this embodiment, the communication and external control module is composed of RS232, RS485 and external isolation control signal circuit. The RS232 and RS485 are serial communication. The single-chip microcomputer can receive the host computer instructions through the serial communication interface. The single-chip microcomputer sends relevant IO control information according to the instructions to control and schedule the orderly operation of the entire system. The external isolation control signal is a related signal sent by an external device through the external isolation control signal interface. After receiving the signal, the single-chip microcomputer executes the corresponding control command. This module circuit adopts the existing technology, and one of the implementation circuits is as follows Fig.12 shown.

[0037] like Figure 2 As shown, in this embodiment, the constant voltage and constant current module includes a voltage gear switching circuit, a current gear switching circuit, a voltage feedback circuit and a constant voltage and constant current setting circuit, all of which are connected to the single-chip control module; a current feedback circuit connected to the current gear switching circuit, a sum-difference operation circuit connected to the constant voltage and constant current setting circuit, a current readback circuit connected to the sum-difference operation circuit, and a voltage readback circuit connected to both the voltage feedback circuit and the sum-difference operation circuit; wherein the voltage feedback circuit is also connected to the voltage gear switching circuit. The current / voltage gear switching circuit adjusts the voltage division of the voltage sampling resistor and the voltage division of the current sampling resistor by controlling the MOS tube and the analog switch of the single-chip microcomputer, and the voltage division is superimposed with the output of the voltage follower in the DAC constant voltage setting circuit, and sent to the post-stage operational amplifier together.

[0038] like Figure 3 As shown, in this embodiment, the voltage gear switching circuit includes an optocoupler isolation chip U206 whose first port is connected to the single-chip control module via a resistor R242, MOS tubes V203 and V204 whose two gates are connected to the two output ends of the optocoupler isolation chip U206, and resistors R220, R219, R222 and R221 whose two ends are connected in series and connected to a +12V voltage and a -12V voltage respectively; wherein, the sources of the MOS tubes V203 and V204 are interconnected, the common end of the resistors R220 and R219 is connected to the gate of the MOS tube V203, the common end of R222 and R221 is connected to the gate of the MOS tube V204, and the common end of R219 and R222 is connected to the source of the MOS tube V203; the drain of the MOS tube V203 and the drain of V204 are connected to the voltage feedback circuit via resistors R218 and R217 respectively.

[0039] like Figure 4As shown, in this embodiment, the current gear switching circuit includes a transistor V202 whose base is connected to the single-chip control module through a resistor R206 and whose emitter is grounded, a MOS tube V201 whose gate is connected to the collector of the transistor V202, a resistor R205 whose one end is connected to the collector of the transistor V202 and whose other end is connected to a 5V voltage, and a resistor R203 connected between the drain and source of the MOS tube V201; wherein the source of the MOS tube V201 is grounded, and the drain of the MOS tube V201 is connected to the sum-difference operation circuit. The current multi-segment range is realized by the current gear switching circuit, and the collector output of the transistor V202 is controlled by the single-chip IO, thereby controlling the on and off of the switch MOS tube V201, so as to achieve the purpose of connecting R203 to the current sampling circuit or stripping the current sampling circuit, thereby realizing the gear switching. In the 40A gear, R203 strips the current sampling circuit; in the 4A gear, R203 connects to the current sampling circuit.

[0040] like Figure 3 As shown, in this embodiment, the voltage feedback circuit includes a transistor V205 whose base is connected to the single-chip control module via a resistor R227 and whose emitter is grounded, a resistor R110 whose one end is connected to the port connected to the single-chip control module by the resistor R227 and whose other end is grounded, a switch K2 of model HFD3 / 12 whose 8th port is connected to the collector of the transistor V205, a diode D201 whose positive electrode is connected to the 8th port of the switch K2 and whose negative electrode is connected to the 1st port of the switch K2, a resistor R229 connected between the 6th and 7th ports of the switch K2, a resistor R228 connected between the 2nd and 3rd ports of the switch K2, a wiring port JP202 whose 1st and 3rd ports are respectively connected to the 5th and 4th ports of the switch K2, a wiring port JP201 whose 1st and 3rd ports are respectively connected to the 7th and 2nd ports of the switch K2, and a series connection with one end connected to the 6th port of the switch K2 and whose other end is grounded. Resistors R207, R209, R211, R213, and R215; an operational amplifier U202 whose non-inverting input terminal is connected to the common terminal of resistors R213 and R215, and resistors R208, R210, R211, R212, and R214, one end of which is connected in series to the third port of switch K2 and the other end is connected to the inverting input terminal of the operational amplifier U202; a resistor R216 connected between the inverting input terminal and the output terminal of the operational amplifier U202, and capacitors C204 and C205 respectively connected to the positive and negative power supply terminals of the operational amplifier U202 and grounded; wherein the common end of resistors R211 and R213 is connected to the other end of resistor R217 in the voltage gear switching circuit; the common end of resistors R212 and R214 is connected to the other end of resistor R218 in the voltage gear switching circuit; the output terminal of the operational amplifier U202 is connected to the voltage readback circuit.

[0041] like Figure 4 As shown, in this embodiment, the current feedback circuit includes an operational amplifier U201 whose inverting input terminal is connected to the drain of the MOS tube V201 in the current gear switching circuit via a resistor R202, a resistor R201 whose one end is connected to the non-inverting input terminal of the operational amplifier U201 and the other end is grounded, a resistor R204 and a capacitor C203 whose two ends are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U201, and capacitors C201 and C202 respectively connected to the positive and negative power supply terminals of the operational amplifier U201 and grounded; wherein the output terminal of the operational amplifier U201 is connected to the sum and difference operation circuit.

[0042] like Figure 5 As shown, in this embodiment, the constant voltage and constant current setting circuit includes an operational amplifier U205A whose positive input terminal is connected to the single-chip control module via a resistor R239, an operational amplifier U204A whose positive input terminal is connected to the single-chip control module via a resistor R238, a capacitor C217 whose one end is connected to the positive input terminal of the operational amplifier U205A and the other end is grounded, a capacitor C216 whose one end is connected to the positive input terminal of the operational amplifier U204A and the other end is grounded, a capacitor C218 whose one end is connected to the positive power supply terminal of the operational amplifier U205A and the other end is grounded, and capacitors C204 and C215 respectively connected to the positive and negative power supply terminals of the operational amplifier U205A and grounded; wherein, the inverting input terminal of the operational amplifier U205A is connected to the output terminal, the inverting input terminal of the operational amplifier U204A is connected to the output terminal, and the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U204A are both connected to the sum and difference operation circuit.

[0043] like Figure 5As shown, in this embodiment, the sum-difference operation circuit includes an operational amplifier U301A whose inverting input terminal is connected to the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U201 via a resistor R310, and whose non-inverting input terminal is connected to the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U201 via a resistor R311 respectively; a resistor R313 and a capacitor C310 connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U301A; capacitors C308 and C309 connected to the positive and negative power supply terminals of the operational amplifier U301A and grounded respectively; an operational amplifier U301B whose non-inverting input terminal is connected to the output terminal of the operational amplifier U205A via a resistor R308; a capacitor C303 connected between the inverting input terminal and the output terminal of the operational amplifier U301B; and capacitors C304 connected in series to the positive and negative power supply terminals of the operational amplifier U301B. Resistor R306 and capacitor C304 are connected between the inverting input terminal and the output terminal; resistor R304 having one end connected to the inverting input terminal of the operational amplifier U301B and the other end grounded, resistor R305 having one end connected to the inverting input terminal of the operational amplifier U301B and the other end connected to a -12V voltage, resistors R307 and R309 having one end connected to the non-inverting input terminal of the operational amplifier U301B, and capacitor C306 connected to the other end of resistor R309; wherein the other end of capacitor C306 is connected to the other end of resistor R307 and then connected to a voltage readback circuit; the common end of resistor R311 connected to the operational amplifier U201 is connected to a current readback circuit; the output terminal of the operational amplifier U301A and the output terminal of the operational amplifier U301B are output to an external isolation circuit.

[0044] like Figure 6As shown, in this embodiment, the voltage readback circuit includes an analog switch chip U2 of model ADG419BRZ-REEL, a resistor R7 connected between the second port of the analog switch chip U2 and the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit, an operational amplifier U203A whose inverting input end is connected to the first port of the analog switch chip U2, a resistor R235 whose one end is connected to the inverting input end of the operational amplifier U203A and the other end is connected to the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit, A resistor R233 with one end connected to the positive input of the operational amplifier U203A and the other end connected to the ground, a resistor R234 with one end connected to the positive input of the operational amplifier U203A and the other end connected to a 5V voltage, a resistor R236 and a capacitor C211 connected in parallel between the inverting input and output of the operational amplifier U203A, and a capacitor C213 with one end connected to the positive power supply of the operational amplifier U203A and the other end connected to the ground; wherein the output of the operational amplifier U203A is connected to the single-chip control module via a resistor R237. The voltage readback circuit and the voltage gear switching circuit are used to realize a multi-stage voltage range. R242 in the voltage gear switching circuit is connected to the single-chip control module, and the output of the optical coupler U206 is controlled through the single-chip IO, thereby controlling the on and off of the switch MOS tubes V203 and V204, so as to achieve the purpose of connecting the resistors R217 and R218 to the voltage feedback circuit or stripping the voltage feedback circuit, thereby realizing gear switching. Similarly, in the voltage readback circuit, the S1 channel of the analog switch chip U2 is controlled by the MCU IO to connect R7 to the readback circuit or remove the readback circuit, thereby realizing the gear switching. In the 150V gear, R217 and R218 are connected to the voltage sampling circuit, and R7 is removed from the readback circuit; in the 50V gear, R217 and R218 are removed from the voltage sampling circuit, and R7 is removed from the readback circuit; in the 18V gear, R217 and R218 are removed from the voltage sampling circuit, and R7 is connected to the readback circuit.

[0045] like Figure 7 As shown, in this embodiment, the current readback circuit includes an operational amplifier U203B whose non-phase input terminal is connected to one end of a resistor R311 in the sum-difference operation circuit via a resistor R230, a resistor R231 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a capacitor C209 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a resistor R232 whose one end is connected to the output terminal of the operational amplifier U203B, and a capacitor C210 whose one end is connected to the other end of the resistor R232 and whose other end is grounded; wherein, the inverting input terminal of the operational amplifier U203B is connected to the output terminal; and the common end of the resistor R232 and the capacitor C210 is connected to the single-chip control module.

[0046] Through the above design, the utility model designs the full range into multiple ranges (voltage: 150V gear, 50V gear, 18V gear; current: full range 40A gear, 4A gear). From the results, the maximum gear has the same design accuracy as the full range gear. Although the other gears have the same resolution as the full range gear, the lower the gear, the smaller the division value corresponding to each unit resolution, thereby improving the design accuracy.

[0047] The above embodiment is only one of the preferred implementation modes of the present utility model and should not be used to limit the protection scope of the present utility model. Any changes or modifications that are made to the main design concept and spirit of the present utility model without any substantive significance, as long as the technical problems solved are still consistent with the present utility model, should be included in the protection scope of the present utility model.

Claims

1. A multi-range constant voltage and constant current test circuit, characterized in that: It includes a single-chip control module, and a power supply module, a constant voltage and constant current module, a power amplifier module, and a communication and external control module all connected to the single-chip control module; the single-chip control module controls and exchanges information with other functional modules to ensure coordinated operation between the modules and monitor the working status of each module in real time; the power supply module provides power to each module to ensure the normal operation of each functional module; the power amplifier module constantly adjusts the input voltage or current from the constant voltage and constant current module; the communication and external control module is used to control the single-chip control module through a host computer.

2. A multi-range constant voltage and constant current test circuit according to claim 1, characterized in that: The constant voltage and constant current module includes a voltage gear switching circuit, a current gear switching circuit, a voltage feedback circuit and a constant voltage and constant current setting circuit, all of which are connected to the single-chip microcomputer control module; a current feedback circuit connected to the current gear switching circuit, a sum-and-difference operation circuit connected to the constant voltage and constant current setting circuit, a current readback circuit connected to the sum-and-difference operation circuit, and a voltage readback circuit connected to both the voltage feedback circuit and the sum-and-difference operation circuit; wherein the voltage feedback circuit is also connected to the voltage gear switching circuit.

3. A multi-range constant voltage and constant current test circuit according to claim 2, characterized in that: The voltage gear switching circuit includes an optocoupler isolation chip U206 whose first port is connected to the single-chip control module via a resistor R242, MOS tubes V203 and V204 whose two gates are connected to the two output ends of the optocoupler isolation chip U206, and resistors R220, R219, R222 and R221 whose two ends are connected in series and connected to a +12V voltage and a -12V voltage respectively; wherein the sources of the MOS tubes V203 and V204 are interconnected, the common end of the resistors R220 and R219 is connected to the gate of the MOS tube V203, the common end of R222 and R221 is connected to the gate of the MOS tube V204, and the common end of R219 and R222 is connected to the source of the MOS tube V203; the drain of the MOS tube V203 and the drain of V204 are connected to the voltage feedback circuit via resistors R218 and R217 respectively.

4. A multi-range constant voltage and constant current test circuit according to claim 3, characterized in that: The current gear switching circuit includes a transistor V202 whose base is connected to the single-chip control module via a resistor R206 and whose emitter is grounded, a MOS transistor V201 whose gate is connected to the collector of the transistor V202, a resistor R205 whose one end is connected to the collector of the transistor V202 and whose other end is connected to a 5V voltage, and a resistor R203 connected between the drain and source of the MOS transistor V201; wherein the source of the MOS transistor V201 is grounded, and the drain of the MOS transistor V201 is connected to the sum-difference operation circuit.

5. A multi-range constant voltage and constant current test circuit according to claim 4, characterized in that: The voltage feedback circuit includes a transistor V205 whose base is connected to the single-chip control module via a resistor R227 and whose emitter is grounded, a resistor R110 whose one end is connected to the port connected to the single-chip control module by the resistor R227 and whose other end is grounded, a switch K2 of model HFD3 / 12 whose eighth port is connected to the collector of the transistor V205, a diode D201 whose positive electrode is connected to the eighth port of the switch K2 and whose negative electrode is connected to the first port of the switch K2, a resistor R229 connected between the sixth and seventh ports of the switch K2, a resistor R228 connected between the second and third ports of the switch K2, a wiring port JP202 whose first and third ports are respectively connected to the fifth and fourth ports of the switch K2, a wiring port JP201 whose first and third ports are respectively connected to the seventh and second ports of the switch K2, and a resistor R20 connected in series whose one end is connected to the sixth port of the switch K2 and whose other end is grounded.

7. R209, R211, R213, R215; an operational amplifier U202 whose non-inverting input terminal is connected to the common terminal of resistors R213 and R215, and resistors R208, R210, R211, R212, and R214 whose one end is connected in series to the third port of switch K2 and the other end is connected to the inverting input terminal of the operational amplifier U202; a resistor R216 connected between the inverting input terminal and the output terminal of the operational amplifier U202, and capacitors C204 and C205 respectively connected to the positive and negative power supply terminals of the operational amplifier U202 and grounded; wherein the common end of resistors R211 and R213 is connected to the other end of resistor R217 in the voltage gear switching circuit; the common end of resistors R212 and R214 is connected to the other end of resistor R218 in the voltage gear switching circuit; the output terminal of the operational amplifier U202 is connected to the voltage readback circuit.

6. A multi-range constant voltage and constant current test circuit according to claim 5, characterized in that: The current feedback circuit includes an operational amplifier U201 whose inverting input terminal is connected to the drain of the MOS tube V201 in the current gear switching circuit via a resistor R202, a resistor R201 whose one end is connected to the non-inverting input terminal of the operational amplifier U201 and whose other end is grounded, a resistor R204 and a capacitor C203 whose two ends are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U201, and capacitors C201 and C202 which are respectively connected to the positive and negative power supply terminals of the operational amplifier U201 and are grounded; wherein the output terminal of the operational amplifier U201 is connected to the sum and difference operation circuit.

7. A multi-range constant voltage and constant current test circuit according to claim 6, characterized in that: The constant voltage and constant current setting circuit includes an operational amplifier U205A whose positive input terminal is connected to the single-chip control module via a resistor R239, an operational amplifier U204A whose positive input terminal is connected to the single-chip control module via a resistor R238, a capacitor C217 whose one end is connected to the positive input terminal of the operational amplifier U205A and whose other end is grounded, a capacitor C216 whose one end is connected to the positive input terminal of the operational amplifier U204A and whose other end is grounded, a capacitor C218 whose one end is connected to the positive power supply terminal of the operational amplifier U205A and whose other end is grounded, and capacitors C204 and C215 which are respectively connected to the positive and negative power supply terminals of the operational amplifier U205A and are grounded; wherein, the inverting input terminal of the operational amplifier U205A is connected to the output terminal, the inverting input terminal of the operational amplifier U204A is connected to the output terminal, and the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U204A are both connected to the sum and difference operation circuit.

8. A multi-range constant voltage and constant current test circuit according to claim 7, characterized in that: The sum-difference operation circuit includes an operational amplifier U301A whose inverting input terminal is connected to the output terminal of the operational amplifier U205A and the output terminal of the operational amplifier U201 via a resistor R310 and a non-inverting input terminal via a resistor R311, respectively; a resistor R313 and a capacitor C310 connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U301A; capacitors C308 and C309 connected to the positive and negative power supply terminals of the operational amplifier U301A and grounded, respectively; an operational amplifier U301B whose non-inverting input terminal is connected to the output terminal of the operational amplifier U205A via a resistor R308; a capacitor C303 connected between the inverting input terminal and the output terminal of the operational amplifier U301B; and a capacitor C303 connected in series to the inverting input terminal of the operational amplifier U301B. Resistor R306 and capacitor C304 are connected to the output end; resistor R304 with one end connected to the inverting input end of the operational amplifier U301B and the other end grounded, resistor R305 with one end connected to the inverting input end of the operational amplifier U301B and the other end connected to a -12V voltage, resistors R307 and R309 with one end connected to the non-inverting input end of the operational amplifier U301B, and capacitor C306 connected to the other end of resistor R309; wherein the other end of capacitor C306 is connected to the other end of resistor R307 and then connected to a voltage readback circuit; the common end of resistor R311 connected to the operational amplifier U201 is connected to a current readback circuit; the output end of the operational amplifier U301A and the output end of the operational amplifier U301B are output to an external isolation circuit.

9. A multi-range constant voltage and constant current test circuit according to claim 8, characterized in that: The voltage readback circuit includes an analog switch chip U2 of model ADG419BRZ-REEL, a resistor R7 connected between the second port of the analog switch chip U2 and the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit, an operational amplifier U203A whose inverting input end is connected to the first port of the analog switch chip U2, a resistor R235 whose one end is connected to the inverting input end of the operational amplifier U203A and the other end is connected to the common end of the capacitor C306 and the resistor R307 in the sum-difference operation circuit, and one end is connected to the operational amplifier U203A. A resistor R233 is connected to the non-inverting input terminal of the amplifier U203A and the other end is grounded, a resistor R234 has one end connected to the non-inverting input terminal of the operational amplifier U203A and the other end is connected to a 5V voltage, and after being connected in parallel, the two ends are connected to a resistor R236 and a capacitor C211 between the inverting input terminal and the output terminal of the operational amplifier U203A, and a capacitor C213 has one end connected to the positive power supply terminal of the operational amplifier U203A and the other end is grounded; wherein, the output terminal of the operational amplifier U203A is connected to the single-chip control module via a resistor R237.

10. A multi-range constant voltage and constant current test circuit according to claim 9, characterized in that: The current readback circuit includes an operational amplifier U203B whose non-phase input terminal is connected to one end of a resistor R311 in a sum-difference operation circuit via a resistor R230, a resistor R231 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a capacitor C209 whose one end is connected to the non-phase input terminal of the operational amplifier U203B and whose other end is grounded, a resistor R232 whose one end is connected to the output terminal of the operational amplifier U203B, and a capacitor C210 whose one end is connected to the other end of the resistor R232 and whose other end is grounded; wherein, the inverting input terminal of the operational amplifier U203B is connected to the output terminal; and the common end of the resistor R232 and the capacitor C210 is connected to a single-chip control module.

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