Solid-state low-power-consumption high-precision insulation resistance test circuit

Abstract

The utility model discloses a solid-state low-power-consumption high-precision insulation resistance test circuit which comprises a high-voltage access circuit, a voltage acquisition and amplification circuit, an A / D converter, an embedded microprocessor and an RS485 bus interface module, the high-voltage access circuit is provided with a high-voltage optocoupler circuit, the voltage acquisition and amplification circuit is connected with a loop to be tested, and the A / D converter is connected with the embedded microprocessor. The A / D converter is connected with the voltage acquisition and amplification circuit, the embedded microprocessor is connected with the A / D converter and the high-voltage access circuit, and the RS485 bus interface module is connected to the embedded microprocessor through the signal isolation driver. According to the utility model, the high-voltage optocoupler circuit is designed to replace a conventional mechanical relay, so that faults caused by contact abrasion or damage can be reduced, and the test reliability of the initiating explosive device is improved; meanwhile, the on time and the off time of the high-voltage optocoupler circuit are stable, a high-voltage source can be quickly and timely disconnected, time out-of-tolerance is avoided, and the state change of the insulation resistor can be timely and effectively detected, so that the performance test requirement of the insulation resistor is met.

Description

Technical Field

[0001] This utility model relates to the field of pyrotechnic performance testing technology, specifically a solid-state low-power high-precision insulation resistance testing circuit, and more particularly a solid-state low-power high-precision insulation resistance testing circuit for pyrotechnic performance testing. Background Technology

[0002] Pyrotechnic devices are key components of bridge circuits or detonation control systems, and an important part of weapon system technical preparation. Their insulation resistance performance requirements are: to withstand a large current for a short period without changing the resistance value within the rated time, and to rapidly reach a very high temperature and disconnect after the rated time. Therefore, the accuracy of resistance current-carrying time testing is crucial. However, existing test circuits mostly use mechanical relays to control the start and stop of the external power switch. Due to poor contact and arcing of the relay contacts, this can lead to difficulties in relay starting and failure to disconnect power in time, resulting in severe time deviations. Therefore, existing test circuits cannot meet the performance testing requirements for insulation resistance. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a solid-state low-power high-precision insulation resistance test circuit to solve the technical problems mentioned in the prior art.

[0004] A solid-state, low-power, high-precision insulation resistance testing circuit includes:

[0005] The high-voltage access circuit includes a high-voltage optocoupler circuit, which is used to connect the circuit under test to the output terminal of the high-voltage power supply so as to input a test voltage to the circuit under test.

[0006] A voltage acquisition and amplification circuit is connected to the circuit under test and is used to acquire the test voltage signal of the circuit under test and adjust it to a preset range;

[0007] An A / D converter is connected to the voltage acquisition and amplification circuit to convert the test voltage signal output by the voltage acquisition and amplification circuit into a digital signal.

[0008] An embedded microprocessor, connected to the A / D converter and the high-voltage access circuit, is used to receive the digital signal uploaded by the A / D converter and control the connection / disconnection of the high-voltage optocoupler circuit;

[0009] The RS485 bus interface module is connected to the embedded microprocessor via a signal isolation driver. The signal isolation driver is used to isolate interference signals in the test results output by the embedded microprocessor, so that the isolated test results can be output to the display terminal through the RS485 bus interface module.

[0010] Optionally, the high-voltage access circuit further includes:

[0011] A secondary power supply module, wherein the input terminal of the secondary power supply module is connected to the output terminal of the high-voltage power supply;

[0012] A power boost module is provided, with its input terminal connected to the output terminal of the secondary power module and its output terminal connected to the input terminal of the high-voltage optocoupler circuit. The power boost module is used to adjust the output voltage of the secondary power module to match the test voltage of the circuit under test and input it to the high-voltage optocoupler circuit.

[0013] Optionally, the high-voltage optocoupler circuit includes:

[0014] An optocoupler relay has several input / output channels. The anode of the optocoupler relay is connected to a 3.3V power supply, the cathode of the optocoupler relay is connected to the embedded microprocessor via a signal line, the collector of the optocoupler relay is connected to the output terminal of the high-voltage power supply, and the emitter of the optocoupler relay is connected to the input terminal of the circuit under test.

[0015] The first resistor R1 is connected in series on the connection line between the anode of the optocoupler relay and the 3.3V power supply;

[0016] The second resistor R2 is connected in series on the connection line between the collector of the optocoupler relay and the output terminal of the high-voltage power supply.

[0017] Diode D1 is connected in reverse parallel at the input terminal of the circuit under test.

[0018] Optionally, the voltage acquisition and amplification circuit includes a resistor bridge circuit and two amplification and sampling circuits;

[0019] The resistor bridge circuit consists of a third resistor R3, a short-circuit protection resistor RX, a first adjustable resistor, and a second adjustable resistor connected in series. The other end of the third resistor R3 is connected in series to the output terminal of the circuit under test, and the other end of the second adjustable resistor is connected in series to the common terminal of the high-voltage power supply.

[0020] One of the amplifier circuits is connected in series with the first adjustable resistor, and the other amplifier circuit is connected in parallel with the second adjustable resistor. The outputs of the two amplifier circuits are respectively connected to the input of the A / D converter.

[0021] The resistance of the third resistor R3 is 5MΩ;

[0022] The resistance of the short-circuit protection resistor RX is 1MΩ-1GΩ.

[0023] Optionally, the amplification sampling circuit includes:

[0024] An operational amplifier is provided, wherein the first and eighth pins of the operational amplifier are connected to an adjustment resistor; the second and third pins of the operational amplifier are connected in parallel to a first capacitor C1; the fourth pin of the operational amplifier is connected to the negative terminal of a 5V power supply; the fifth pin of the operational amplifier is grounded; and the connection line between the fifth pin of the operational amplifier and the ground terminal is connected in series with the connection line between the fourth pin and the negative terminal of the 5V power supply to a second capacitor C2; the sixth pin of the operational amplifier is connected to the input terminal of the A / D converter; the seventh pin of the operational amplifier is connected to the positive terminal of the 5V power supply; and the connection line between the seventh pin of the operational amplifier and the positive terminal of the 5V power supply to the ground terminal is connected in series with a third capacitor C3.

[0025] A fifth resistor R5 and a sixth resistor R6 are connected in series on the connection line between the first capacitor C1 and the second pin of the operational amplifier, and the other end of the sixth resistor R6 is grounded.

[0026] The first capacitor C1 is connected to the third pin of the operational amplifier by a seventh resistor R7 and an eighth resistor R8 in series, and the other end of the eighth resistor R8 is grounded.

[0027] The fourth capacitor C4 is connected in parallel to either the first adjustable resistor or the second adjustable resistor;

[0028] The connection lines of the fifth resistor R5 and the sixth resistor R6 are connected in parallel with the connection lines of the seventh resistor R7 and the eighth resistor R8 to the second adjustable resistor, or the connection lines of the fifth resistor R5 and the sixth resistor R6 are connected to the common terminal of the high voltage power supply, and the connection lines of the seventh resistor R7 and the eighth resistor R8 are connected in series to the input terminal of the first adjustable resistor.

[0029] A ninth resistor R9 is connected in series on the connection line between the sixth pin of the operational amplifier and the input terminal of the A / D converter.

[0030] A fifth capacitor C5 is connected in series between the ninth resistor R9 and the connection line between the input terminal of the A / D converter and the ground terminal.

[0031] Optionally, the first adjustable resistor and the second adjustable resistor are respectively provided with a sliding rheostat P and a fourth resistor R4 connected in series.

[0032] The resistance of the sliding rheostat P is 20-100kΩ;

[0033] The resistance of the fourth resistor R4 is 116-286KΩ.

[0034] Optionally, the RS485 bus interface module includes:

[0035] An RS485 bus driver is connected to the signal isolation driver;

[0036] The RS485 bus interface is connected to the RS485 bus driver.

[0037] Optionally, the embedded microprocessor is an STM32F103CBT6 chip, and the embedded microprocessor has an SPI interface, which is used to connect to the A / D converter;

[0038] The PB12 interface of the embedded microprocessor is connected to the clock interface of the A / D converter;

[0039] The PA8 interface of the embedded microprocessor is connected to the chip select interface of the A / D converter;

[0040] The PB14 interface of the embedded microprocessor is connected to the data output interface of the A / D converter;

[0041] The PB13 interface of the embedded microprocessor is connected to the data input interface of the A / D converter.

[0042] The beneficial effects that this utility model can produce include:

[0043] This invention provides a solid-state, low-power, high-precision insulation resistance testing circuit. During insulation resistance testing, a high voltage is used. To ensure testing safety, a voltage acquisition and amplification circuit is designed to monitor the test voltage. When the test voltage exceeds a preset value, a high-voltage optocoupler circuit is driven to disconnect the high-voltage source, thus executing a protection action. By replacing the traditional mechanical relay with a high-voltage optocoupler circuit, faults caused by contact wear or damage are reduced, improving the reliability of pyrotechnic device testing. Simultaneously, the high-voltage optocoupler circuit has stable conduction and cutoff times, enabling rapid and timely disconnection of the high-voltage source, avoiding time errors, and allowing for timely and effective detection of insulation resistance changes to meet insulation resistance performance testing requirements. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the architecture of a solid-state low-power high-precision insulation resistance testing circuit according to the present invention.

[0045] Figure 2 In this utility model Figure 1 A schematic diagram of the high-voltage optocoupler circuit;

[0046] Figure 3 In this utility model Figure 1A schematic diagram of the voltage acquisition and amplification circuit;

[0047] Figure 4 In this utility model Figure 1 A schematic diagram of signal transmission for an A / D converter, embedded microprocessor, signal isolation driver, and RS485 bus interface module;

[0048] In the diagram: 1. Embedded microprocessor, 2. High-voltage optocoupler circuit, 3. Circuit under test, 4. Voltage acquisition and amplification circuit, 5. A / D converter, 6. Signal isolation driver, 7. RS485 bus interface module. Detailed Implementation

[0049] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0050] Please see Figures 1-4As shown, this utility model provides a solid-state low-power high-precision insulation resistance testing circuit, including a high-voltage access circuit, a voltage acquisition and amplification circuit 4, an A / D converter 5, an embedded microprocessor 1, a signal isolation driver 6, and an RS485 bus interface module 7. The high-voltage access circuit has a high-voltage optocoupler circuit 2, which is used to connect the circuit under test 3 (i.e., insulation resistance) to the output terminal of the high-voltage power supply to input a test voltage to the circuit under test 3. The voltage acquisition and amplification circuit 4 is connected to the circuit under test 3 and is used to acquire the test voltage signal of the circuit under test 3 and adjust it to a preset range. The A / D converter 5 is connected to... Voltage acquisition and amplification circuit 4 converts the test voltage signal output by voltage acquisition and amplification circuit 4 into a digital signal; embedded microprocessor 1 is connected to A / D converter 5 and high voltage access circuit, used to receive the digital signal uploaded by A / D converter 5 and control the on / off of high voltage optocoupler circuit 2; RS485 bus interface module 7 is connected to embedded microprocessor 1 through signal isolation driver 6, which is used to isolate interference signals in the test results output by embedded microprocessor 1, so that the isolated test results can be output to the display terminal through RS485 bus interface module 7. In the above, high voltage is used during insulation resistance testing. To ensure testing safety, a voltage acquisition and amplification circuit 4 is designed to monitor the test voltage. When the test voltage exceeds a preset value (set to be greater than 10% of the specified value in this embodiment), the high-voltage optocoupler circuit 2 is driven to disconnect the high-voltage source to perform a protection action. By designing the high-voltage optocoupler circuit 2 to replace the conventional mechanical relay, faults caused by contact wear or damage can be reduced, improving the testing reliability of pyrotechnics. At the same time, the conduction and cutoff times of the high-voltage optocoupler circuit 2 are stable, enabling it to quickly and timely disconnect the high-voltage source, avoiding time deviations, and allowing for timely and effective detection of changes in the state of the insulation resistance to meet the performance testing requirements of the insulation resistance.

[0051] In this embodiment, the high-voltage access circuit also includes a secondary power supply module and a power boost module. The input terminal of the secondary power supply module is connected to the output terminal of the high-voltage power supply to provide a stable voltage source for the test circuit. The input terminal of the power boost module is connected to the output terminal of the secondary power supply module, and the output terminal of the power boost module is connected to the input terminal of the high-voltage optocoupler circuit 2 to adjust the output voltage of the secondary power supply module to be consistent with the test voltage of the circuit under test 3, and input it to the high-voltage optocoupler circuit 2.

[0052] In this embodiment, the high-voltage optocoupler circuit 2 includes an optocoupler relay, a first resistor R1, a second resistor R2, and a diode D1. The optocoupler relay is a TLP227G model, which has two input / output channels. The anode of the optocoupler relay is connected to a 3.3V power supply, and the cathode of the optocoupler relay is connected to an embedded microprocessor 1 via a signal line. The embedded microprocessor 1 sends control signals to control the conduction and disconnection of the optocoupler relay. The collector of the optocoupler relay is connected to the output terminal of the high-voltage power supply, and the emitter of the optocoupler relay is connected to the input terminal of the circuit under test 3. The first resistor R1 is connected in series in the connection line between the anode of the optocoupler relay and the 3.3V power supply, and the second resistor R2 is connected in series in the connection line between the collector of the optocoupler relay and the output terminal of the high-voltage power supply. The first resistor R1 and the second resistor R2 act as current-limiting resistors to adjust the current flowing through the circuit and limit the current within a preset range to protect other components in the circuit from damage due to excessive current. The diode D1 is connected in reverse parallel at the input terminal of the circuit under test 3. In the above, as... Figure 2 As shown, one input / output channel of the optocoupler relay is connected to the test circuit. The optocoupler relay can be used to transmit small signals. Its maximum triggering current for the LED is 3mA, which means that it can conduct without triggering the pyrotechnic device to test the insulation performance. At the same time, the maximum conduction current is 120mA, which means that the power consumption during the test is low, which helps to extend the service life of the pyrotechnic device and reduce energy consumption. In addition, a diode D1 of model M4007 is connected in reverse parallel at the input terminal of the circuit under test 3 to prevent the optocoupler relay from being damaged due to abnormal input signal.

[0053] In this embodiment, the voltage acquisition and amplification circuit 4 includes a resistor bridge circuit and two amplification and sampling circuits. The resistor bridge circuit consists of a third resistor R3, a short-circuit protection resistor RX, a first adjustable resistor, and a second adjustable resistor connected in series. The other end of the third resistor R3 is connected in series to the output terminal of the circuit under test 3, and the other end of the second adjustable resistor is connected in series to the common terminal of the high-voltage power supply. The input terminal of one amplification and sampling circuit is connected in series to the first adjustable resistor, and the input terminal of the remaining amplification and sampling circuit is connected in parallel to the second adjustable resistor. The output terminals of the two amplification and sampling circuits are respectively connected to the input terminals of the A / D converter 5. The resistance of the third resistor R3 is 5MΩ, and the resistance of the short-circuit protection resistor RX is 1MΩ-1GΩ. Specifically, the amplification sampling circuit includes an operational amplifier. The first and eighth pins of the operational amplifier are connected to adjustment resistors. The second and third pins of the operational amplifier are connected in parallel to a first capacitor C1. The fourth pin of the operational amplifier is connected to the negative terminal of a 5V power supply. The fifth pin of the operational amplifier is grounded, and the connection line between the fifth pin and the ground terminal and the connection line between the fourth pin and the negative terminal of the 5V power supply is connected in series with a second capacitor C2. The sixth pin of the operational amplifier is connected to the input terminal of the A / D converter 5. The seventh pin of the operational amplifier is connected to the positive terminal of the 5V power supply, and the connection line between the seventh pin and the positive terminal of the 5V power supply and the ground terminal is connected in series with a third capacitor C3. A fifth resistor R5 and a sixth resistor R6 are connected in series on the connection line between the first capacitor C1 and the second pin of the operational amplifier. The other end of resistor R6 is grounded; the connection line between the first capacitor C1 and the third pin of the operational amplifier is connected in series with the seventh resistor R7 and the eighth resistor R8, the other end of the eighth resistor R8 being grounded; the fourth capacitor C4 is connected in parallel to either the first or second adjustable resistor; the connection line between the fifth resistor R5 and the sixth resistor R6 is connected in parallel with the connection line between the seventh resistor R7 and the eighth resistor R8 to the second adjustable resistor, or the connection line between the fifth resistor R5 and the sixth resistor R6 is connected to the common terminal of the high-voltage power supply, and the connection line between the seventh resistor R7 and the eighth resistor R8 is connected in series to the input terminal of the first adjustable resistor; the connection line between the sixth pin of the operational amplifier and the input terminal of the A / D converter 5 is connected in series with the ninth resistor R9; the connection line between the ninth resistor R9 and the input terminal of the A / D converter 5 and the ground terminal is connected in series with the fifth capacitor C5. The first and second adjustable resistors are respectively equipped with a sliding rheostat P and a fourth resistor R4 connected in series; the resistance of the sliding rheostat P is 20-100kΩ; the resistance of the fourth resistor R4 is 116-286kΩ. In the above, such as Figure 3 As shown, a resistor R0 with a resistance of 0 is connected in series between the sixth resistor R6 of the second amplification sampling circuit and the fourth resistor R42 of the second adjustable resistor, so that the sixth resistor R6 is connected in parallel to the common terminal of the high voltage power supply.

[0054] In the above, the resistor bridge circuit uses a 1% high-precision sampling resistor for voltage acquisition. The short-circuit protection resistor RX has a resistance of 5MΩ, the fourth resistor R4 of the first adjustable resistor has a resistance of 286kΩ, the fourth resistor R4 of the second adjustable resistor has a resistance of 116KΩ, and the sliding rheostat P of the second adjustable resistor has a resistance of 20KΩ, used to adjust the resistance value of the small-range resistor bridge circuit. The sliding rheostat P of the first adjustable resistor has a resistance of 100KΩ, used to adjust the resistance value of the large-range resistor bridge circuit, so that the resistor bridge circuit can input different voltages to the two amplification sampling circuits.

[0055] In the above, the operational amplifier is model IN128AN. The input voltage of the resistor bridge circuit is input to the IN+ and IN- terminals of the operational amplifier to appropriately adjust the voltage difference between the IN+ and IN- terminals. The amplification factor of the operational amplifier is G = 1 + 50K / Rg. Figure 2 As shown in the circuit diagram, Rg = ∞, therefore the operational amplifier gain G = 1, and the operational amplifier potential difference U... O =U + -U - Assuming the interference signal is U X When interference occurs at the IN+ pin of the operational amplifier, it will also interfere with the IN- pin. When interference is present, the voltage input to the third pin of the operational amplifier is U. + +U X Because the operational amplifier is a differential operational amplifier, as shown in the voltage differential operation formula: (U + +U X )-(U - +U X )=U + -U - This effectively eliminated the interference signal.

[0056] In the above, assuming the resistance range of the circuit under test 3 is 1MΩ to 1GΩ, the design method of the resistor bridge circuit and the channel range design method of the two amplification sampling circuits include the following steps:

[0057] The first step is to calculate the resistance value of the resistor bridge circuit and estimate the range of the second adjustable resistor based on the sampling voltage of the operational amplifier. Assume that the sampling resistance value of the second adjustable resistor is X, and the minimum sampling voltage is 100mV and the maximum value is 4.75V.

[0058] When the resistance of the circuit under test 3 is 1MΩ, then the formula is:

[0059] 250V / (5MΩ+1MΩ+X)=100mV / X, so X=2.4kΩ can be calculated;

[0060] 250V / (5MΩ+1MΩ+X)=4.75V / X, so X=116kΩ;

[0061] When the resistance of the circuit under test 3 is 1 GΩ, then the formula is:

[0062] 250V / (5MΩ+1GΩ+X)=100mV / X, so X=402kΩ can be calculated;

[0063] 250V / (5MΩ+1GΩ+X)=4.75V / X, so X=19.4MΩ can be calculated;

[0064] Therefore, the sampling resistor value of the second adjustable resistor is selected as 116KΩ, and the sampling resistor value of the first adjustable resistor is selected as 402kΩ-116kΩ=286kΩ.

[0065] Step 2: Based on the calculation results in Step 1, select the appropriate resistor bridge circuit and calculate the range of each channel of the two amplification sampling circuits. Assuming the resistance of the amplification sampling circuit is Y, the insulation resistance test range of the second amplification sampling circuit on the second adjustable resistor is:

[0066] 250V / (402kΩ+5MΩ+Y)=100mV / 116KΩ, so Y=284.5MΩ can be calculated;

[0067] 250V / (402kΩ+5MΩ+Y)=4.75 / 116KΩ, so Y=703kΩ can be calculated;

[0068] Insulation resistance test range of the first amplification sampling circuit on the first adjustable resistor.

[0069] 250V / (402kΩ+5MΩ+Y)=100mV / 402kΩ, so Y=999.5MΩ can be calculated;

[0070] 250V / (402kΩ+5MΩ+Y)=4.75 / 402kΩ, so Y=15.7MΩ;

[0071] The operational amplifier adjusts the insulation resistance test range of the second amplification sampling circuit to 703kΩ~15.7MΩ, and the insulation resistance test range of the first amplification sampling circuit to 284.5MΩ~999.5MΩ; wherein, the range of 15.7MΩ~284.5MΩ can be measured by both amplification sampling circuits. In this embodiment, the resistance sampling of the circuit under test 3 is measured by the second amplification sampling circuit.

[0072] In this embodiment, the RS485 bus interface module 7 includes an RS485 bus driver and an RS485 bus interface. The RS485 bus driver is connected to the signal isolation driver 6; the RS485 bus interface is connected to the RS485 bus driver.

[0073] In this embodiment, the embedded microprocessor 1 is an STM32F103CBT6 chip. The embedded microprocessor 1 has an SPI interface, which is used to connect to the A / D converter 5. The A / D converter 5 is an ADS1256. For example... Figure 3 As shown, the PB12 interface of embedded microprocessor 1 is connected to the clock interface of A / D converter 5; the PA8 interface of embedded microprocessor 1 is connected to the chip select interface of A / D converter 5; the PB14 interface of embedded microprocessor 1 is connected to the data output interface of A / D converter 5; and the PB13 interface of embedded microprocessor 1 is connected to the data input interface of A / D converter 5. In this configuration, the ADS1256 A / D converter 5 provides up to 24-bit resolution, capable of capturing minute signal changes, and is suitable for high-precision measurement and signal processing. It is combined with a pre-stage precision sampling resistor bridge circuit to sample the input voltage signal, ensuring that the voltage signal is within the input range of A / D converter 5. The STM32F103CBT6 chip serves as the main control chip to process the sampled data and is responsible for SPI communication with A / D converter 5 to ensure high-speed and stable data transmission. Simultaneously, embedded microprocessor 1 and signal isolation driver 6 are connected to the secondary power supply module to ensure stable power supply for the test circuit and avoid inaccurate data acquisition due to power fluctuations.

Claims

1. A solid state low power consumption high precision insulation resistance test circuit, characterized in that, The application relates to a high-voltage access circuit, which comprises the following components: a high-voltage optical coupling circuit (2) for connecting a to-be-tested circuit (3) to the output end of a high-voltage power supply to input a test voltage to the to-be-tested circuit (3); a voltage acquisition and amplification circuit (4) connected to the to-be-tested circuit (3) for acquiring the test voltage signal of the to-be-tested circuit (3) and adjusting the test voltage signal to a preset range; an A / D converter (5) connected to the voltage acquisition and amplification circuit (4) for converting the test voltage signal output by the voltage acquisition and amplification circuit (4) into a digital signal; an embedded microprocessor (1) connected to the A / D converter (5) and the high-voltage access circuit for receiving the digital signal uploaded by the A / D converter (5) and controlling the on / off of the high-voltage optical coupling circuit (2); and an RS485 bus interface module (7) connected to the embedded microprocessor (1) through a signal isolation driver (6), wherein the signal isolation driver (6) is used for isolating interference signals in the test results output by the embedded microprocessor (1) to output the test results after isolation to a display terminal through the RS485 bus interface module (7). The high-voltage access circuit further comprises: a secondary power supply module, the input end of which is connected to the output end of the high-voltage power supply; and a power supply voltage boosting module, the input end of which is connected to the output end of the secondary power supply module, the output end of which is connected to the input end of the high-voltage optical coupling circuit (2) and used for adjusting the output voltage of the secondary power supply module to be consistent with the test voltage of the to-be-tested circuit (3) and inputting the high-voltage optical coupling circuit (2). The high-voltage optical coupling circuit (2) comprises: an optical coupling relay with a plurality of input and output channels, the anode of the optical coupling relay being connected to a 3.3V power supply, the cathode of the optical coupling relay being connected to the embedded microprocessor (1) through a signal line, the collector of the optical coupling relay being connected to the output end of the high-voltage power supply, and the emitter of the optical coupling relay being connected to the input end of the to-be-tested circuit (3); a first resistor R1 arranged in series on the connection line between the anode of the optical coupling relay and the 3.3V power supply; a second resistor R2 arranged in series on the connection line between the collector of the optical coupling relay and the output end of the high-voltage power supply; and a diode D1 arranged in reverse parallel on the input end of the to-be-tested circuit (3). The voltage acquisition and amplification circuit (4) comprises a resistance bridge circuit and two-way amplification and sampling circuits. The resistance bridge circuit comprises a third resistor R3, a short-circuit protection resistor RX, a first adjustable resistor and a second adjustable resistor arranged in series, one end of the third resistor R3 being connected to the output end of the to-be-tested circuit (3) in series, and one end of the second adjustable resistor being connected to the common end of the high-voltage power supply in series. ​ 2. The solid-state low-power high-precision insulation resistance test circuit according to claim 1, characterized in that, ​ ​ ​ 3. The solid state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that, ​ ​ ​ ​ ​ 4. The solid state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that, ​ ​ One input end of the amplification circuit is connected in series with the first adjustable resistor, and the remaining input end of the amplification circuit is connected in parallel with the second adjustable resistor, and the output ends of the two amplification circuits are respectively connected to the input end of the A / D converter (5); The third resistor R3 has a resistance of 5MΩ; The short-circuit protection resistor RX has a resistance of 1MΩ-1GΩ.

5. The solid state low power consumption high precision insulation resistance test circuit according to claim 4, characterized in that, The amplification sampling circuit comprises: An operational amplifier, a first pin and an eighth pin of the operational amplifier are connected to an adjusting resistor, a second pin and a third pin of the operational amplifier are connected in parallel to a first capacitor C1, a fourth pin of the operational amplifier is connected to a negative pole of a 5V power supply, a fifth pin of the operational amplifier is grounded, a connection line between the fifth pin and the ground is connected in series with a second capacitor C2 on a connection line between the fourth pin and the negative pole of the 5V power supply, a sixth pin of the operational amplifier is connected to an input end of the A / D converter (5), a seventh pin of the operational amplifier is connected to a positive pole of the 5V power supply, and a connection line between the seventh pin and the positive pole of the 5V power supply is connected in series with a third capacitor C3 between the ground; The first capacitor C1 is connected in series with a fifth resistor R5 and a sixth resistor R6 on a connection line between the second pin and the ground of the operational amplifier, and the other end of the sixth resistor R6 is grounded; The first capacitor C1 is connected in series with a seventh resistor R7 and an eighth resistor R8 on a connection line between the third pin and the ground of the operational amplifier, and the other end of the eighth resistor R8 is grounded; A fourth capacitor C4 is connected in parallel to the first adjustable resistor or the second adjustable resistor; The connection line between the fifth resistor R5 and the sixth resistor R6 is connected in parallel with the connection line between the seventh resistor R7 and the eighth resistor R8 to the second adjustable resistor, or the connection line between the fifth resistor R5 and the sixth resistor R6 is connected to a common end of a high-voltage power supply, and the connection line between the seventh resistor R7 and the eighth resistor R8 is connected in series to the input end of the first adjustable resistor; The sixth pin of the operational amplifier is connected in series with a ninth resistor R9 on a connection line between the sixth pin and the input end of the A / D converter (5); The ninth resistor R9 and the input end of the A / D converter (5) are connected in series with a fifth capacitor C5 between the ground.

6. The solid state low power consumption high precision insulation resistance test circuit according to claim 4, characterized in that, The first adjustable resistor and the second adjustable resistor are respectively provided with a slide rheostat P and a fourth resistor R4 connected in series; The slide rheostat P has a resistance of 20-100kΩ; The fourth resistor R4 has a resistance of 116-286KΩ.

7. The solid state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that, The RS485 bus interface module (7) comprises: An RS485 bus driver connected to the signal isolation driver (6); An RS485 bus interface connected to the RS485 bus driver.

8. The solid state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that, The embedded microprocessor (1) is an STM32F103CBT6 chip, the embedded microprocessor (1) has an SPI interface, and the SPI interface is used to access the A / D converter (5). The PB12 interface of the embedded microprocessor (1) is connected with the clock interface of the A / D converter (5); The PA8 interface of the embedded microprocessor (1) is connected with the chip selection interface of the A / D converter (5); The PB14 interface of the embedded microprocessor (1) is connected with the data output terminal interface of the A / D converter (5); The PB13 interface of the embedded microprocessor (1) is connected with the data input terminal interface of the A / D converter (5).

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