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

Abstract

A solid-state low-power-consumption high-precision insulation resistance test circuit disclosed by the present invention 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, the A / D converter is connected with the voltage acquisition and amplification circuit, and the embedded microprocessor is connected with the RS485 bus interface module. 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 invention, 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] The present invention relates to the technical field of pyrotechnic performance testing, and in particular to a solid-state low-power consumption high-precision insulation resistance testing circuit, in particular to a solid-state low-power consumption high-precision insulation resistance testing circuit for pyrotechnic performance testing. Background Art

[0002] Explosives are key components of bridge circuits or detonation control systems, and are also an important part of the technical preparation of weapon systems. The insulation resistance performance requirements are: to withstand a large current in a short period of time, and the resistance value does not change within the rated time, and to quickly reach a very high temperature and disconnect after the rated time. Therefore, the accuracy of the resistance power-on time test is very important. However, when testing existing test circuits, most mechanical relays are used to control the start and stop of external power switches. Due to factors such as poor contact of relay contacts and arcing, it will cause the relay to start with difficulty, and the power cannot be cut off in time, resulting in serious time deviations. Therefore, the existing test circuit cannot meet the performance test requirements of insulation resistance. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a solid-state low-power consumption 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 test circuit, comprising:

[0005] A high-voltage access circuit has a high-voltage optocoupler circuit, and the high-voltage optocoupler circuit is used to connect the circuit to be tested to the output end of the high-voltage power supply to input a test voltage to the circuit to be tested;

[0006] A voltage acquisition and amplification circuit, connected to the circuit to be tested, for acquiring a test voltage signal of the circuit to be tested and adjusting it to a preset range;

[0007] An A / D converter, 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, for receiving the digital signal uploaded by the A / D converter and controlling the on / off of the high-voltage optocoupler circuit;

[0009] The RS485 bus interface module is connected to the embedded microprocessor through a signal isolation driver, and the signal isolation driver is used to isolate the interference signal in the test result output by the embedded microprocessor, so as to output the isolated test result 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, the input end of the secondary power supply module is connected to the output end of the high voltage power supply;

[0012] A power boost module, the input end of the power boost module is connected to the output end of the secondary power module, and the output end of the power boost module is connected to the input end of the high-voltage optocoupler circuit, for adjusting the output voltage of the secondary power module to be consistent with the test voltage of the circuit to be tested, and inputting it into the high-voltage optocoupler circuit.

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

[0014] An optical coupler relay having a plurality of input and output channels, wherein the anode of the optical coupler relay is connected to a 3.3V power supply, the cathode of the optical coupler relay is connected to the embedded microprocessor via a signal line, the collector of the optical coupler relay is connected to the output end of the high-voltage power supply, and the emitter of the optical coupler relay is connected to the input end of the circuit to be tested;

[0015] A first resistor R1 is arranged in series on a connection line between the anode of the photocoupler relay and the 3.3V power supply;

[0016] A second resistor R2 is arranged in series on a connection line between the collector of the optical coupling relay and the output end of the high voltage power supply;

[0017] The diode D1 is connected in reverse parallel at the input end of the circuit to be tested.

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

[0019] The resistance bridge circuit is a third resistor R3, a short-circuit protection resistor RX, a first adjustable resistor and a second adjustable resistor which are sequentially connected in series, the other end of the third resistor R3 is connected in series to the output end of the circuit to be tested, and the other end of the second adjustable resistor is connected in series to the common end of the high-voltage power supply;

[0020] The input end of one of the amplifier circuits is connected in series to the first adjustable resistor, the input end of the remaining amplifier circuit is connected in parallel to the second adjustable resistor, and the output ends of the two amplifier circuits are connected to the input ends of the A / D converter respectively;

[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, wherein the first pin and the eighth pin of the operational amplifier are connected to an adjustment resistor, the second pin and the third pin 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 electrode of a 5V power supply, the fifth pin of the operational amplifier is grounded, and a connection line between the fifth pin of the operational amplifier and the ground end and a connection line between the fourth pin and the negative electrode of the 5V power supply are connected in series to a second capacitor C2, the sixth pin of the operational amplifier is connected to the input end of the A / D converter, the seventh pin of the operational amplifier is connected to the positive electrode of the 5V power supply, and a third capacitor C3 is connected in series between the connection line between the seventh pin of the operational amplifier and the positive electrode of the 5V power supply and the ground end;

[0025] A fifth resistor R5 and a sixth resistor R6 are connected in series in sequence on a 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] A seventh resistor R7 and an eighth resistor R8 are sequentially connected in series on a connection line between the first capacitor C1 and the third pin of the operational amplifier, and the other end of the eighth resistor R8 is grounded;

[0027] a fourth capacitor C4, wherein the fourth capacitor C4 is connected in parallel to the first adjustable resistor or the second adjustable resistor;

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

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

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

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

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

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

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

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

[0036] RS485 bus interface, connected to the RS485 bus driver.

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

[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 terminal interface of the A / D converter.

[0042] The beneficial effects that the present invention can produce include:

[0043] The present invention provides a solid-state low-power consumption high-precision insulation resistance test circuit, in which high voltage is used during insulation resistance testing. In order to ensure test safety, a voltage acquisition and amplification circuit is designed to monitor the test voltage so that when the test voltage exceeds a preset value, a high-voltage optocoupler circuit is driven to disconnect the high-voltage source to perform a protection action. Specifically, by designing a high-voltage optocoupler circuit to replace the previous mechanical relay, faults caused by contact wear or damage can be reduced, and the test reliability of pyrotechnics can be improved. At the same time, the on-time and off-time of the high-voltage optocoupler circuit are stable, and the high-voltage source can be disconnected quickly and timely to avoid time deviations. The state changes of the insulation resistance can be detected in a timely and effective manner to meet the performance test requirements of the insulation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of a solid-state low-power and high-precision insulation resistance test circuit of the present invention;

[0045] Figure 2 For the present invention Figure 1 Structural diagram of a high-voltage optocoupler circuit;

[0046] Figure 3 For the present invention Figure 1 A schematic diagram of the structure of a voltage acquisition and amplification circuit;

[0047] Figure 4 For the present invention Figure 1 Schematic diagram of signal transmission of A / D converter, embedded microprocessor, signal isolation driver and RS485 bus interface module;

[0048] In the figure: 1. embedded microprocessor, 2. high-voltage optocoupler circuit, 3. circuit to be tested, 4. voltage acquisition and amplification circuit, 5. A / D converter, 6. signal isolation driver, 7. RS485 bus interface module. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] See also Figure 1-Figure 4As shown, the present invention provides a solid-state low-power consumption and high-precision insulation resistance test 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 optical coupling circuit 2, the high-voltage optical coupling circuit 2 is used to connect the circuit to be tested 3 (i.e., the insulation resistance) to the output end of the high-voltage power supply to input a test voltage to the circuit to be tested 3; the voltage acquisition and amplification circuit 4 is connected to the circuit to be tested 3, and is used to collect the test voltage signal of the circuit to be tested 3 and adjust it to a preset range; the A / D converter 5 is connected to the circuit to be tested 3, and ... The embedded microprocessor 1 is connected to the A / D converter 5 and the high-voltage access circuit to receive the digital signal uploaded by the A / D converter 5 and control the on / off of the high-voltage optocoupler circuit 2; the RS485 bus interface module 7 is connected to the embedded microprocessor 1 through the signal isolation driver 6, and the signal isolation driver 6 is used to isolate the interference signal in the test result output by the embedded microprocessor 1, so as to output the isolated test result to the display terminal through the RS485 bus interface module 7. In the above, a high voltage is used during the insulation resistance test. In order to ensure the safety of the test, the test voltage is monitored by designing a voltage acquisition and amplification circuit 4 so that 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; wherein, by designing a high-voltage optocoupler circuit 2 to replace the previous mechanical relay, it is possible to reduce failures caused by contact wear or damage and improve the test reliability of pyrotechnics; at the same time, the on-time and off-time of the high-voltage optocoupler circuit 2 are stable, and the high-voltage source can be disconnected quickly and timely to avoid time deviations, and the state changes of the insulation resistance can be detected in a timely and effective manner to meet the performance test 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 end of the secondary power supply module is connected to the output end of the high-voltage power supply to provide a stable voltage source for the test circuit; the input end of the power boost module is connected to the output end of the secondary power supply module, and the output end of the power boost module is connected to the input end of the high-voltage optocoupler circuit 2, which is used to adjust the output voltage of the secondary power supply module to be consistent with the test voltage of the circuit to be tested 3, and input it into 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 model of the optocoupler relay is TLP227G, which has two input and 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, so as to control the conduction and disconnection of the optocoupler relay by sending a control signal through the embedded microprocessor 1; the collector of the optocoupler relay is connected to the output end of the high-voltage power supply, and the emitter of the optocoupler relay is connected to the input end of the circuit to be tested 3; the first resistor R1 is arranged in series on the connection line between the anode of the optocoupler relay and the 3.3V power supply, and the second resistor R2 is arranged in series on the connection line between the collector of the optocoupler relay and the output end of the high-voltage power supply. The first resistor R1 and the second resistor R2 are used as current-limiting resistors to adjust the current passing through the circuit and limit the current within a preset range to protect other components in the circuit from being damaged by excessive current; the diode D1 is arranged in reverse parallel at the input end of the circuit to be tested 3. In the above, as Figure 2 As shown, one input and output channel of the optocoupler relay is connected to the test circuit, wherein the optocoupler relay can be used to transmit small signals, and its maximum current for triggering the LED is 3mA, which means that it can be turned on to detect the insulation performance without triggering the pyrotechnics; at the same time, the maximum conduction current is 120mA, which means that the power consumed during the test is low, which helps to extend the service life of the pyrotechnics and reduce energy consumption; and, a diode D1 of model M4007 is reversely connected in parallel at the input end of the circuit 3 to be tested to prevent damage to the optocoupler relay due to abnormal input signals.

[0053] In this embodiment, the voltage acquisition and amplification circuit 4 includes a resistance bridge circuit and two amplification and sampling circuits; the resistance bridge circuit is a third resistor R3, a short-circuit protection resistor RX, a first adjustable resistor and a second adjustable resistor which are arranged in series in sequence, and the other end of the third resistor R3 is connected in series to the output end of the circuit to be measured 3, and the other end of the second adjustable resistor is connected in series to the common end of the high-voltage power supply; the input end of one of the amplification and sampling circuits is connected in series to the first adjustable resistor, and the input end of the remaining amplification and sampling circuit is connected in parallel to the second adjustable resistor, and the output ends of the two amplification and sampling circuits are respectively connected to the input ends of the A / D converter 5; wherein the resistance value of the third resistor R3 is 5MΩ; the resistance value of the short-circuit protection resistor RX is 1MΩ-1GΩ. Specifically, the amplification sampling circuit includes an operational amplifier, the first pin and the eighth pin of the operational amplifier are connected to the adjustment resistor, the second pin and the third pin of the operational amplifier are connected in parallel to the first capacitor C1, the fourth pin of the operational amplifier is connected to the negative electrode of the 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 end and the connection line between the fourth pin and the negative electrode of the 5V power supply are connected in series with the second capacitor C2, the sixth pin of the operational amplifier is connected to the input end of the A / D converter 5, the seventh pin of the operational amplifier is connected to the positive electrode of the 5V power supply, and the connection line between the seventh pin of the operational amplifier and the positive electrode of the 5V power supply and the ground end is connected in series with the third capacitor C3; the connection line between the first capacitor C1 and the second pin of the operational amplifier is connected in series with the fifth resistor R5 and the sixth resistor R6, and the sixth resistor R7 is connected in series with the fifth resistor R8. The other end of the resistor R6 is connected to the ground; the seventh resistor R7 and the eighth resistor R8 are connected in series in sequence on the connection line between the first capacitor C1 and the third pin of the operational amplifier, and the other end of the eighth resistor R8 is connected to the ground; the 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 and the connection line between the seventh resistor R7 and the eighth resistor R8 are connected in parallel to the second adjustable resistor, or the connection line between the fifth resistor R5 and the sixth resistor R6 is connected to the common end 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 end of the first adjustable resistor; the connection line between the sixth pin of the operational amplifier and the input end 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 end of the A / D converter 5 and the ground end is connected in series with the fifth capacitor C5. Among them, the first adjustable resistor and the second adjustable resistor are respectively provided with a sliding variable resistor P and a fourth resistor R4 connected in series with each other; the resistance value of the sliding variable resistor P is 20-100kΩ; the resistance value of the fourth resistor R4 is 116-286KΩ. In the above, if 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 end of the high-voltage power supply.

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

[0055] In the above, the model of the operational amplifier is IN128AN, and the input voltage of the resistance bridge circuit is input to the IN+ terminal and the IN- terminal of the operational amplifier, so that the voltage difference between the IN+ terminal and the IN- terminal is appropriately adjusted by the operational amplifier; wherein, the amplification factor of the operational amplifier is G=1+50K / Rg, such as Figure 2 As shown, in the circuit diagram, Rg = ∞, so the gain of the operational amplifier G = 1, and the potential difference U O =U + -U - , assuming the interference signal is U X When it interferes with the IN+ terminal of the operational amplifier, it will also interfere with the IN- terminal of the operational amplifier. When there is interference, 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 - , which effectively eliminates the interference signal.

[0056] In the above, assuming that the resistance range of the circuit 3 to be measured is 1MΩ~1GΩ, the design method of the resistance 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 resistance bridge circuit, and estimate the value range of the second adjustable resistor according to the sampling voltage of the operational amplifier. Assume that the sampling resistance value of the second adjustable resistor is X, the minimum value of the sampling voltage is 100mV, and the maximum value is 4.75V;

[0058] When the resistance of the circuit 3 to be tested is 1MΩ, the formula is:

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

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

[0061] When the resistance of the circuit 3 to be tested is 1GΩ, the formula is:

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

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

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

[0065] Step 2: Select a resistance bridge circuit according to the calculation result of step 1, and calculate the channel range of each of the two amplifying and sampling circuits; assuming that the resistance value of the amplifying and sampling circuit is Y, the insulation resistance test range of the second amplifying and sampling circuit on the second adjustable resistor is:

[0066] 250V / (402kΩ+5MΩ+Y)=100mV / 116KΩ, and Y=284.5MΩ.

[0067] 250V / (402kΩ+5MΩ+Y)=4.75 / 116KΩ, and Y=703kΩ.

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

[0069] 250V / (402kΩ+5MΩ+Y)=100mV / 402kΩ, and Y=999.5MΩ.

[0070] 250V / (402kΩ+5MΩ+Y)=4.75 / 402kΩ, and 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 is 284.5MΩ~999.5MΩ; wherein, the measuring range of 15.7MΩ~284.5MΩ can be measured jointly by the two amplification sampling circuits. In this embodiment, the resistance sampling of the circuit 3 to be tested 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; and the RS485 bus interface is connected to the RS485 bus driver.

[0073] In this embodiment, the embedded microprocessor 1 is a STM32F103CBT6 chip, and the embedded microprocessor 1 has an SPI interface, which is used to access an A / D converter 5. The model of the A / D converter 5 is ADS1256. Figure 3 As shown, the PB12 interface of the embedded microprocessor 1 is connected to the clock interface of the A / D converter 5; the PA8 interface of the embedded microprocessor 1 is connected to the chip select interface of the A / D converter 5; the PB14 interface of the embedded microprocessor 1 is connected to the data output interface of the A / D converter 5; and the PB13 interface of the embedded microprocessor 1 is connected to the data input interface of the A / D converter 5. In the above, the ADS1256 type A / D converter 5 provides up to 24-bit resolution, can capture the change of tiny signals, and is suitable for high-precision measurement and signal processing; and combines the front-stage precision sampling resistor bridge circuit to sample the input voltage signal to ensure that the voltage signal is within the input range of the A / D converter 5. Among them, the STM32F103CBT6 chip is used as the main control chip to process the sampled data, and is responsible for SPI communication with the A / D converter 5 to ensure high-speed and stable data transmission; at the same time, the embedded microprocessor 1 and the signal isolation driver 6 are respectively connected to the secondary power supply module to ensure that the power supply of the test circuit is stable and avoid inaccurate data collection due to power supply fluctuations.

Claims

1. A solid-state low-power high-precision insulation resistance test circuit, characterized in that: include: A high-voltage access circuit comprises a high-voltage optical coupling circuit (2), wherein the high-voltage optical coupling circuit (2) is used to connect a circuit to be tested (3) to an output end of a high-voltage power supply so as to input a test voltage to the circuit to be tested (3); A voltage collection and amplification circuit (4) is connected to the circuit to be tested (3) and is used to collect a test voltage signal of the circuit to be tested (3) and adjust it to a preset range; An A / D converter (5) connected to the voltage acquisition and amplification circuit (4) to convert the test voltage signal output by the voltage acquisition and amplification circuit (4) into a digital signal; An embedded microprocessor (1) is connected to the A / D converter (5) and the high-voltage access circuit, and is used to receive the digital signal uploaded by the A / D converter (5) and control the on / off of the high-voltage optical coupling circuit (2); The RS485 bus interface module (7) is connected to the embedded microprocessor (1) via a signal isolation driver (6), wherein the signal isolation driver (6) is used to isolate interference signals in the test results output by the embedded microprocessor (1), so as to output the isolated test results to a display terminal via the RS485 bus interface module (7).

2. A solid-state low-power consumption high-precision insulation resistance test circuit according to claim 1, characterized in that: The high voltage access circuit also includes: A secondary power supply module, the input end of the secondary power supply module is connected to the output end of the high voltage power supply; A power boost module, the input end of the power boost module is connected to the output end of the secondary power module, and the output end of the power boost module is connected to the input end of the high-voltage optocoupler circuit (2), and is used to adjust the output voltage of the secondary power module to be consistent with the test voltage of the circuit to be tested (3), and input it into the high-voltage optocoupler circuit (2).

3. A solid-state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that: The high-voltage optocoupler circuit (2) comprises: An optical coupler relay having a plurality of input and output channels, wherein the anode of the optical coupler relay is connected to a 3.3V power supply, the cathode of the optical coupler relay is connected to the embedded microprocessor (1) via a signal line, the collector of the optical coupler relay is connected to the output end of the high-voltage power supply, and the emitter of the optical coupler relay is connected to the input end of the circuit to be tested (3); A first resistor R1 is arranged in series on a connection line between the anode of the photocoupler relay and the 3.3V power supply; A second resistor R2 is arranged in series on a connection line between the collector of the optical coupling relay and the output end of the high voltage power supply; The diode D1 is arranged in reverse parallel at the input end of the circuit to be tested (3).

4. A solid-state low power consumption high precision insulation resistance test circuit according to claim 1, characterized in that: 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 which are sequentially connected in series, the other end of the third resistor R3 being connected in series to the output end of the circuit to be tested (3), and the other end of the second adjustable resistor being connected in series to the common end of the high-voltage power supply; The input end of one of the amplifier circuits is connected in series to the first adjustable resistor, the input end of the remaining amplifier circuit is connected in parallel to the second adjustable resistor, and the output ends of the two amplifier circuits are respectively connected to the input ends of the A / D converter (5); The resistance of the third resistor R3 is 5MΩ; The resistance of the short-circuit protection resistor RX is 1MΩ-1GΩ.

5. A 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, wherein the first pin and the eighth pin of the operational amplifier are connected to an adjustment resistor, the second pin and the third pin 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 electrode of a 5V power supply, the fifth pin of the operational amplifier is grounded, and a connection line between the fifth pin of the operational amplifier and the ground end and a connection line between the fourth pin and the negative electrode of the 5V power supply are connected in series to a second capacitor C2, the sixth pin of the operational amplifier is connected to an input end of the A / D converter (5), the seventh pin of the operational amplifier is connected to the positive electrode of the 5V power supply, and a third capacitor C3 is connected in series between the connection line between the seventh pin of the operational amplifier and the positive electrode of the 5V power supply and the ground end; A fifth resistor R5 and a sixth resistor R6 are connected in series in sequence on a 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; A seventh resistor R7 and an eighth resistor R8 are sequentially connected in series on a connection line between the first capacitor C1 and the third pin of the operational amplifier, and the other end of the eighth resistor R8 is grounded; a fourth capacitor C4, wherein the fourth capacitor C4 is connected in parallel to the first adjustable resistor or the second adjustable resistor; The connection line of the fifth resistor R5 and the sixth resistor R6 and the connection line of the seventh resistor R7 and the eighth resistor R8 are connected in parallel to the second adjustable resistor, or the connection line of the fifth resistor R5 and the sixth resistor R6 are connected to the common end of the high-voltage power supply, and the connection line of the seventh resistor R7 and the eighth resistor R8 are connected in series to the input end of the first adjustable resistor; A ninth resistor R9 is connected in series to the connection line between the sixth pin of the operational amplifier and the input end of the A / D converter (5); A fifth capacitor C5 is connected in series between the connection line between the ninth resistor R9 and the input end of the A / D converter (5) and the ground end.

6. A 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 sliding rheostat P and a fourth resistor R4 connected in series with each other; The resistance of the sliding resistor P is 20-100 kΩ; The resistance of the fourth resistor R4 is 116-286KΩ.

7. A 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); RS485 bus interface, connected to the RS485 bus driver.

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

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