Insulation monitor for high-voltage direct-current equipment

Abstract

The utility model relates to the field of electric energy detection, in particular to an insulation monitor for high-voltage direct-current equipment, and the monitor comprises a resistance detection module which is used for detecting the resistance value of an HVPos end to the ground and the resistance value of an HVNeg end to the ground; and the voltage detection module is used for detecting the voltage of the high-voltage loop. The method has the effects of realizing higher reaction speed and reducing the cost.

Description

Technical Field

[0001] This application relates to the field of electrical energy detection, and in particular to an insulation monitoring instrument for high-voltage DC equipment. Background Technology

[0002] With the rise of the new energy industry, high-voltage DC charging piles and string photovoltaic systems are being used more and more. Their DC voltage can reach 800V-1000V or even higher. To ensure their safe use, it is necessary to monitor the insulation status and voltage of their high-voltage busbars. Once an abnormality occurs, the insulation monitoring instrument can quickly upload data to alert users and ensure the safety of relevant users and other personnel.

[0003] Currently available insulation testing equipment suffers from insufficient electrical clearance between high and low voltage levels, leading to significant measurement errors when there is substantial capacitance in the line. Fluctuations in the voltage source, interference, damage to the current sensor, or reduced sensitivity can all cause large deviations in the measurement results. Utility Model Content

[0004] To address this issue, this application provides an insulation monitoring instrument for high-voltage DC equipment.

[0005] This application provides an insulation monitoring instrument for high-voltage DC equipment, which adopts the following technical solution:

[0006] An insulation monitoring instrument for high-voltage direct current equipment includes:

[0007] The resistance detection module is used to detect the resistance value of the HV_Pos terminal to ground and the resistance value of the HV_Neg terminal to ground.

[0008] The voltage detection module is used to detect the voltage in the high-voltage circuit.

[0009] By adopting the above technical solution, the resistance and voltage values ​​can be detected.

[0010] Optionally, the resistance detection module includes:

[0011] The measurement unit is used to measure the voltage drop to ground at the HV_Pos terminal or the voltage drop to ground at the HV_Neg terminal to obtain the InAMC_P signal;

[0012] The isolation differential unit receives the InAMC_P signal, performs power isolation, and then performs differential operation to obtain the Diff_P differential signal and the Diff_N differential signal.

[0013] The differential-to-single-ended unit receives the Diff_P differential signal and the Diff_N differential signal, performs calculations to obtain the ADC_Insu signal, and thus obtains the resistance value of the HV_Pos terminal to ground or the resistance value of the HV_Neg terminal to ground.

[0014] By adopting the above technical solution, isolation is performed on the high-voltage side, a differential signal is generated on the low-voltage side, and then the resistance value is measured by converting the differential signal to a single-ended signal. At the same time, isolation is performed to improve circuit safety.

[0015] Optionally, the measurement unit includes a chip U1 and a resistor R11. The eleventh pin of the chip U1 is electrically connected to the HV_Pos terminal, the third pin of the chip U1 is electrically connected to the Switch_Pos terminal, the resistor R11 is connected in series with the ninth pin of the chip U1, and the InAMC_P signal is output between the ninth pin of the chip U1 and the resistor R11.

[0016] By adopting the above technical solution, the HV_Pos terminal is sampled through chip U1.

[0017] Optionally, the measurement unit further includes a chip U2, the ninth pin of which is electrically connected to the HV_Neg terminal, the third pin of which is electrically connected to the Switch_Neg terminal, and the eleventh pin of which is electrically connected between the ninth pin of the chip U1 and the resistor R11, and outputs the InAMC_P signal.

[0018] By adopting the above technical solution, sampling the HV_Neg terminal through chip U2, and realizing the monitoring of insulation resistance in two ways, it is possible to achieve second-level monitoring under the condition of large capacitance value, while greatly reducing cost.

[0019] Optionally, the isolation differential unit includes a chip U3, the sixth pin of the chip U3 receives the InAMC_P signal, the chip U3 performs isolation, the tenth pin of the chip U3 outputs the Diff_N differential signal, and the eleventh pin of the chip U3 outputs the Diff_P differential signal.

[0020] By adopting the above technical solution, high voltage isolation is achieved through chip U3, thereby improving the safety of the circuit.

[0021] Optionally, the differential-to-single-ended unit includes an operational amplifier U4, a resistor R22, a capacitor C3, and a capacitor C56. The inverting input of the operational amplifier U4 receives the Diff_N differential signal, and the non-inverting input of the operational amplifier U4 receives the Diff_P differential signal. The resistor R22 is electrically connected between the inverting input and the output of the operational amplifier U4. The capacitor C3 is connected in parallel with the resistor R22. The capacitor C56 is electrically connected between the output of the operational amplifier U4 and the ground terminal GND. The output of the operational amplifier U4 outputs the ADC_Insu signal.

[0022] By adopting the above technical solution, differential signal to single-ended signal conversion can be achieved.

[0023] Optionally, the voltage detection module includes:

[0024] The sampling differential unit is used to sample the voltage of the high-voltage circuit, and after power isolation, calculate the Diff_P_Bat differential signal and the Diff_N_Bat differential signal.

[0025] The voltage-to-single-ended unit receives the Diff_P_Bat differential signal and the Diff_N_Bat differential signal, performs calculations to obtain the ADC_Bat signal, and thus obtains the high voltage value.

[0026] By adopting the above technical solution, the voltage value can be detected.

[0027] Optionally, the sampling differential unit includes a chip U5 and a resistor R42. The resistor R42 is connected in series in the high-voltage circuit. The sixth pin of the chip U5 is electrically connected to one end of the resistor R42. The seventh and eighth pins of the chip U5 are connected in parallel and then electrically connected to the other end of the resistor R42. The chip U5 provides isolation. The tenth pin of the chip U5 outputs the Diff_N_Bat differential signal, and the eleventh pin of the chip U5 outputs the Diff_P_Bat differential signal.

[0028] By adopting the above technical solution, the voltage of the high-voltage circuit is sampled through resistor R42, and then isolated through chip U5 to obtain a differential signal.

[0029] Optionally, the voltage-to-single-ended unit includes an operational amplifier U6, capacitor C57, capacitor C15, and resistor R35. The inverting input of the operational amplifier U6 receives the Diff_N_Bat differential signal, and the non-inverting input of the operational amplifier U6 receives the Diff_P_Bat differential signal. Resistor R35 is electrically connected between the inverting input and output of the operational amplifier U6. Capacitor C15 is connected in parallel with resistor R35. Capacitor C57 is electrically connected between the output of the operational amplifier U6 and ground GND. The output of the operational amplifier U6 outputs the ADC_Bat signal.

[0030] By adopting the above technical solution, the voltage value can be calculated by converting the differential signal to a single-ended signal.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] 1. It can achieve second-level monitoring with a large capacitance value, while keeping the cost relatively low.

[0033] 2. To achieve the detection of resistance and voltage values. Attached Figure Description

[0034] Figure 1 This is a circuit diagram of a resistance detection module for an insulation monitoring instrument used in high-voltage DC equipment, according to an embodiment of this application.

[0035] Figure 2 This is a circuit diagram highlighting the measurement unit.

[0036] Figure 3 This is a circuit diagram of the voltage detection module.

[0037] Explanation of reference numerals in the attached diagram: 1. Measurement unit; 2. Isolation differential unit; 3. Differential to single-ended unit; 4. Sampling differential unit; 5. Voltage to single-ended unit. Detailed Implementation

[0038] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0039] This application discloses an insulation monitoring instrument for high-voltage DC equipment. (Refer to...) Figure 1 The insulation monitoring instrument for high voltage DC equipment includes a resistance detection module and a voltage detection module. The resistance detection module is used to detect the resistance value of the HV_Pos terminal to ground and the resistance value of the HV_Neg terminal to ground, and the voltage detection module is used to detect the voltage of the high voltage circuit.

[0040] Reference Figure 1 and Figure 2The resistance detection module includes a measurement unit 1, an isolation differential unit 2, and a differential-to-single-ended unit 3. Measurement unit 1 includes chip U1, chip U2, capacitor C1, resistors R10, R11, R1, R64, R2, R3, R4, R5, R6, R7, R8, capacitors C2 and C51, resistors R12, R65, R13, R14, R15, R16, and R17. Resistors R18, R19, and R9; sockets P1, P2, and P3; the first pin of chip U1 receives a +5V power supply; the eighth pin of chip U1 is electrically connected to ground GND; capacitor C1 is connected in parallel between the first and eighth pins of chip U1; the second pin of chip U1 is connected in parallel to the eighth pin; one end of resistor R10 is connected in series to the third pin of chip U1; and the other end of resistor R10 is electrically connected to the Switch_Pos terminal. Resistors R1, R64, R2, R3, R4, R5, R6, R7, and R8 are connected in series between pin 11 of chip U1 and pin 1 of connector P1. Pin 2 of connector P1 is connected in parallel to pin 1. Connector P1 provides electrical connection for the device under test. Resistor R11 is connected in series between chip U1 and pin 1 of connector P2. Pin 2 of connector P2 is connected in parallel to pin 1. Ground terminal PE is connected in parallel to pin 1 of connector P2. Chip U1 outputs the InAMC_P signal between resistor R11 and chip U1. The first pin of chip U2 receives a +5V power supply. The eighth pin of chip U2 is electrically connected to ground (GND). Capacitor C2 is connected in parallel between the first and eighth pins of chip U1. The second pin of chip U2 is connected in parallel to the eighth pin. Capacitor C51 is connected in parallel between the first and eighth pins of chip U1. One end of resistor R12 is connected in series with the third pin of chip U1, and the other end of resistor R12 is electrically connected to the Switch_Neg pin. Resistors R65, R13, R14, R15, R16, and R17... Resistors R18 and R19 are connected in series between the ninth pin of chip U2 and the first pin of power strip P3. The second pin of power strip P3 is connected in parallel to the first pin. Power strip P3 provides electrical connection for the device under test. The first and second pins of power strip P3 are connected in parallel to the HV_Neg terminal. The eleventh pin of chip U2 outputs the InAMC_P signal and is connected in parallel between the ninth pin of chip U1 and resistor R11. Chips U1 and U2 are of model TPSI2140QDWQRQ1, and power strips P1, P2, and P3 are of model Header 2H.

[0041] Reference Figure 1The isolation differential unit 2 includes chip U3, capacitors C6, C7, C8, C4, C9, C10, C12, C13, and C14, and resistor R24. One end of resistor R24 ​​is connected in series with the sixth pin of chip U3, and the other end of resistor R24 ​​receives the InAMC_P signal. Chip U3 performs isolation. The tenth pin of chip U3 outputs the Diff_N differential signal, and the eleventh pin of chip U3 outputs the Diff_P differential signal. Capacitor C6 is connected in parallel between the first and second pins of chip U3, capacitor C7 is connected in parallel between the first and second pins of chip U3, capacitor C8 is connected in parallel between the third and second pins of chip U3, the first and third pins of chip U3 are connected in parallel, and the second pin of chip U3 is electrically connected to the ground terminal PE. Capacitor C12 is connected in parallel between pins 5 and 8 of chip U3; capacitor C13 is connected in parallel between pins 5 and 8 of chip U3; capacitor C14 is connected in parallel between pins 6 and 8 of chip U3; pin 7 of chip U3 is connected in parallel to pin 8; pin 8 of chip U3 is electrically connected to ground (PE); pin 15 of chip U3 is electrically connected to ground (GND); pins 13 and 16 of chip U3 are electrically connected; capacitor C4 is connected in parallel between pins 16 and 15 of chip U3; pin 12 of chip U3 receives +5V power; pin 9 of chip U3 is electrically connected to ground (GND); capacitor C9 is connected in parallel between pins 9 and 12 of chip U3; capacitor C10 is connected in parallel between pins 9 and 12 of chip U3. Chip U3 is an AMC3330DWE model.

[0042] Reference Figure 1The differential-to-single-ended converter 3 includes an operational amplifier U4, resistors R22, R23, R25, and R26, and capacitors C11, C5, C49, C3, and C56. One end of resistor R23 is connected in series with the inverting input of operational amplifier U4, and the other end of resistor R23 receives the Diff_N differential signal. One end of resistor R25 is connected in series with the non-inverting input of operational amplifier U4, and the other end of resistor R25 receives the Diff_P differential signal. Resistor R22 is connected in parallel between the inverting input and output of operational amplifier U4. Capacitor C3 is connected in parallel with resistor R22. The second pin of operational amplifier U4 is electrically connected to ground (GND). Capacitor C56 is electrically connected to operational amplifier U4. Between the output terminal and the second pin, the fifth pin of operational amplifier U4 receives a +3.3V power supply. One end of capacitor C5 and one end of capacitor C49 are connected in parallel to the fifth pin of operational amplifier U4. The other end of capacitor C5 and the other end of capacitor C49 are connected in parallel to the ground terminal GND. The output terminal of operational amplifier U4 outputs the ADC_Insu signal. One end of capacitor C11 is connected in parallel to the non-inverting input terminal of operational amplifier U4. One end of resistor R26 is connected in parallel to the non-inverting input terminal of operational amplifier U4. The other end of capacitor C11 and the other end of resistor R26 are connected in parallel to the +1.65V power supply terminal. Operational amplifier U4 is a TLV6001 model. The ADC_Insu signal output is sent to the MCU ADC for sampling and measurement, and the resistance value can be obtained.

[0043] Reference Figure 3The voltage detection module includes a differential sampling unit 4 and a voltage-to-single-ended conversion unit 5. The differential sampling unit 4 includes a chip U5, resistors R33, R32, R31, R30, R29, R28, R27, R34, R36, R37, R40, R45, capacitors C18, C19, C20, C24, C25, C26, C17, C21, and C22, and resistors R42, R33, R32, R31, R30, R29, and R28. Resistors R27, R34, R36, R37, and R42 are connected in series in the high-voltage circuit. One end of resistor R30 is connected in series to pin 6 of chip U5, and the other end of resistor R30 is connected in parallel between resistors R42 and R29. Resistor R45 is connected in series to pin 8 of chip U5, and the other end of resistor R45 is connected in parallel between resistors R42 and R28. Pin 7 of chip U5 is connected in parallel to pin 8, and chip U5 provides isolation. Pin 10 of chip U5 outputs a Diff_N_Bat differential signal, and pin 11 of chip U5 outputs a Diff_P_Bat differential signal. The remaining circuitry is identical to that of chip U3, with capacitor C18 replacing capacitor C6, capacitor C19 replacing capacitor C7, capacitor C20 replacing capacitor C8, capacitor C25 replacing capacitor C14, capacitor C24 replacing capacitor C12, capacitor C26 replacing capacitor C13, capacitor C17 replacing capacitor C4, capacitor C21 replacing capacitor C9, and capacitor C22 replacing capacitor C10. Chip U5 uses the AMC3330DWE model.

[0044] Reference Figure 3The voltage-to-single-ended converter 5 includes an operational amplifier U6, resistors R41, R43, R44, R39, R38, capacitors C57, C15, C16, C50, C23, and resistor R35. One end of resistor R38 is connected in series with the inverting input of operational amplifier U6, and the other end of resistor R38 receives the Diff_N_Bat differential signal. One end of resistor R39 is connected in series with the non-inverting input of operational amplifier U6, and the other end of resistor R39 receives the Diff_P_Bat differential signal. Resistor R35 is electrically connected between the inverting input and output of operational amplifier U6. Capacitor C15 is connected in parallel with resistor R35. The second pin of operational amplifier U6 is electrically connected to ground (GND). Capacitor C56 is electrically connected between the output and the second pin of operational amplifier U4. Pin 5 receives a +3.3V power supply. One end of capacitor C16 and one end of capacitor C50 are connected in parallel to pin 5 of operational amplifier U6. The other end of capacitor C16 and the other end of capacitor C50 are connected in parallel to ground GND. Operational amplifier U6 outputs the ADC_Bat signal. One end of capacitor C23 is connected in parallel to the non-inverting input of operational amplifier U4. One end of resistor R41 is connected in parallel to the non-inverting input of operational amplifier U6. The other end of capacitor C23 and the other end of resistor R41 are connected in parallel to one end of resistor R44. The other end of resistor R44 is electrically connected to ground GND. One end of resistor R43 is connected in parallel between resistor R41 and capacitor C23. The other end of resistor R43 is electrically connected to the +1.65V power supply. Operational amplifier U6 is a TLV6001 model. The ADC_Bat signal output is sent to the MCU ADC for sampling and measurement to obtain the high voltage value.

[0045] The implementation principle of an insulation monitoring instrument for high-voltage DC equipment according to an embodiment of this application is as follows: Chip U1 is selected to measure the voltage drop across resistor R11 on the HV_Pos terminal to ground, obtaining the InAMC_P signal. The InAMC_P signal isolates the high and low voltages through chip U3. Chip U3 has a built-in isolation power supply module that detects the voltage drop across resistor R11 on the high-voltage side, generating a Diff_P differential signal and a Diff_N differential signal on the low-voltage side. These signals are then converted from differential to single-ended by operational amplifier U4 and sampled by the MCU ADC. The voltage value can be used to determine the resistance value of the HV_Pos terminal to ground according to the algorithm. Chip U2 is then selected to measure the resistance value of the HV_Neg terminal to ground (PE).

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An insulation monitoring instrument for high-voltage DC equipment, characterized in that, include: The resistance detection module is used to detect the resistance value of the HV_Pos terminal to ground and the resistance value of the HV_Neg terminal to ground. The voltage detection module is used to detect the voltage in the high-voltage circuit.

2. An insulation monitoring instrument for high-voltage DC equipment according to claim 1, characterized in that, The resistance detection module includes: The measurement unit (1) is used to measure the voltage drop to ground at the HV_Pos terminal or the voltage drop to ground at the HV_Neg terminal to obtain the InAMC_P signal; The isolation differential unit (2) receives the InAMC_P signal, performs power isolation, and then performs differential operation to obtain the Diff_P differential signal and the Diff_N differential signal. The differential-to-single-ended unit (3) receives the Diff_P differential signal and the Diff_N differential signal, performs calculations to obtain the ADC_Insu signal, and thus obtains the resistance value of the HV_Pos terminal to ground or the resistance value of the HV_Neg terminal to ground.

3. An insulation monitoring instrument for high-voltage DC equipment according to claim 2, characterized in that: The measurement unit (1) includes a chip U1 and a resistor R11. The eleventh pin of the chip U1 is electrically connected to the HV_Pos terminal, the third pin of the chip U1 is electrically connected to the Switch_Pos terminal, and the resistor R11 is connected in series to the ninth pin of the chip U1. The InAMC_P signal is output between the ninth pin of the chip U1 and the resistor R11.

4. An insulation monitoring instrument for high-voltage DC equipment according to claim 3, characterized in that: The measurement unit (1) also includes a chip U2, the ninth pin of which is electrically connected to the HV_Neg terminal, the third pin of which is electrically connected to the Switch_Neg terminal, and the eleventh pin of which is electrically connected between the ninth pin of the chip U1 and the resistor R11, and outputs the InAMC_P signal.

5. An insulation monitoring instrument for high-voltage DC equipment according to claim 4, characterized in that: The isolation differential unit (2) includes a chip U3. The sixth pin of the chip U3 receives the InAMC_P signal. The chip U3 performs isolation. The tenth pin of the chip U3 outputs the Diff_N differential signal. The eleventh pin of the chip U3 outputs the Diff_P differential signal.

6. An insulation monitoring instrument for high-voltage DC equipment according to claim 5, characterized in that: The differential-to-single-ended unit (3) includes an operational amplifier U4, a resistor R22, a capacitor C3, and a capacitor C56. The inverting input terminal of the operational amplifier U4 receives the Diff_N differential signal, and the non-inverting input terminal of the operational amplifier U4 receives the Diff_P differential signal. The resistor R22 is electrically connected between the inverting input terminal and the output terminal of the operational amplifier U4. The capacitor C3 is connected in parallel with the resistor R22. The capacitor C56 is electrically connected between the output terminal of the operational amplifier U4 and the ground terminal GND. The output terminal of the operational amplifier U4 outputs the ADC_Insu signal.

7. An insulation monitoring instrument for high-voltage DC equipment according to claim 1, characterized in that, The voltage detection module includes: The sampling differential unit (4) is used to sample the voltage of the high voltage circuit and, after power isolation, calculate the Diff_P_Bat differential signal and the Diff_N_Bat differential signal. The voltage to single-ended unit (5) receives the Diff_P_Bat differential signal and the Diff_N_Bat differential signal, performs calculations to obtain the ADC_Bat signal, and thus obtains the high voltage value.

8. An insulation monitoring instrument for high-voltage DC equipment according to claim 7, characterized in that: The sampling differential unit (4) includes a chip U5 and a resistor R42. The resistor R42 is connected in series in the high voltage circuit. The sixth pin of the chip U5 is electrically connected to one end of the resistor R42. The seventh and eighth pins of the chip U5 are connected in parallel and then electrically connected to the other end of the resistor R42. The chip U5 is isolated. The tenth pin of the chip U5 outputs the Diff_N_Bat differential signal, and the eleventh pin of the chip U5 outputs the Diff_P_Bat differential signal.

9. An insulation monitoring instrument for high-voltage DC equipment according to claim 8, characterized in that: The voltage-to-single-ended unit (5) includes an operational amplifier U6, a capacitor C57, a capacitor C15, and a resistor R35. The inverting input terminal of the operational amplifier U6 receives the Diff_N_Bat differential signal, and the non-inverting input terminal of the operational amplifier U6 receives the Diff_P_Bat differential signal. The resistor R35 is electrically connected between the inverting input terminal and the output terminal of the operational amplifier U6. The capacitor C15 is connected in parallel with the resistor R35. The capacitor C57 is electrically connected between the output terminal of the operational amplifier U6 and the ground terminal GND. The output terminal of the operational amplifier U6 outputs the ADC_Bat signal.

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