AC / DC insulation detection method in energy storage system

Abstract

The invention discloses an AC / DC insulation detection method in an energy storage system, and relates to the technical field of power electronics, and the method comprises the following steps: 1, regularly detecting the insulation resistance of high-voltage DC and AC in a PCS, and guaranteeing the normal operation of equipment and personal safety; the relays can be switched to detect the insulation resistance of the direct current positive and negative electrode pair casing, the insulation resistance of the direct current negative electrode pair casing and the insulation resistance of the alternating current live wire pair casing respectively. According to the alternating current and direct current insulation detection method in the energy storage system, the direct current side can be detected, meanwhile, insulation detection can be carried out on the alternating current side, high-voltage alternating current and direct current insulation resistance can be detected at the same time through independent power supply detection, insulation detection can be carried out on the system when high voltage exists or not, sampled data are accurate, and detection accuracy is high. The sampling response is fast, the sampling time can be set, detection is carried out before power-on, and modular integration can be carried out.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to an AC / DC insulation detection method in an energy storage system. Background Art

[0002] Industrial and commercial energy storage equipment is developing rapidly. With the increasing demand of industrial and commercial users for power stability and cost control, the demand for energy storage equipment has increased significantly. Industrial and commercial energy storage systems can not only improve the absorption rate of clean energy, but also reduce power transmission losses, help achieve the dual carbon goals, and continuously improve energy storage technology. Among them, PCS is a vital AC-to-DC or DC-to-AC power conversion equipment in industrial and commercial energy storage equipment (hereinafter collectively referred to as "PCS"). If the insulation of AC and DC does not meet the actual working conditions, there are certain hidden dangers to the safety of equipment and personnel. DC insulation belongs to the insulation resistance between the positive or negative pole and the casing, and AC insulation belongs to the insulation resistance between the L phase and the casing. These insulation problems will also reduce the efficiency of power supply to energy storage equipment.

[0003] The existing solutions have the following problems:

[0004] 1. The current transformer injection solution in the prior art has increased costs, is too large in size, cannot be integrated and modularized, and the detection branch is only a single type of voltage detection, and the detection data is not accurate enough;

[0005] 2. In the prior art, the basic method of the voltage-to-ground method is to add resistance between the housing and the positive and negative electrodes of the high-voltage DC. This method requires the presence of high voltage to perform insulation monitoring, because there is a ground connection here, which often has a certain impact on the insulation system of the entire system. When the entire system is subjected to a withstand voltage test, this part of the circuit must be disconnected or improved, because the measurement switch used in this part generally adopts a tube optocoupler relay, which generally has a low withstand voltage and cannot withstand such a high voltage, which will cause circuit damage. Generally, PCS will adopt this solution for insulation resistance design;

[0006] 3. In general, the PCS of energy storage systems only tests the insulation of the DC end, but does not test the insulation of the AC end, which may also pose certain safety hazards. Summary of the invention

[0007] 1. Technical issues to be solved

[0008] In view of the shortcomings of the prior art, the present invention provides an AC / DC insulation detection method in an energy storage system, which has the advantages of low cost, modular integration, strong anti-interference ability, and small footprint. It solves the problem of the current transformer injection solution in the prior art, which has increased cost, large size, and cannot be integrated and modularized. The detection branch is only a single type of voltage detection, and the detection data is not accurate enough. The ground voltage type in the prior art basically adds resistance between the casing and the positive and negative poles of the high-voltage DC. This method must have a high voltage to perform insulation monitoring, because there is a ground connection here, which often has a certain impact on the insulation system of the entire system. When the entire system is subjected to a withstand voltage test, this part of the circuit must be disconnected or improved, because the measurement switch used in this part generally adopts a tube optocoupler relay, and this relay generally has a low withstand voltage and cannot withstand such a high voltage, which will cause circuit damage. Most PCSs in energy storage systems are designed using this solution.

[0009] (II) Technical solution

[0010] To achieve the above object, the present invention provides the following technical solution: a method for detecting AC / DC insulation in an energy storage system, comprising the following steps:

[0011] Step 1: Regularly test the insulation resistance of high-voltage DC and AC inside the PCS to ensure normal operation of the equipment and personal safety;

[0012] Step 2: By controlling the detection voltage, the relay can be switched to detect the insulation resistance of the DC positive and negative poles to the casing, the DC negative pole to the casing, and the AC live wire to the casing;

[0013] Step 3: The energy storage AC / DC insulation detection system circuit includes: insulation detection circuit of DC positive pole to casing, insulation detection circuit of DC negative pole to casing, insulation resistance detection of AC live wire and casing, DC positive and negative pole AC live wire switching circuit, isolated power supply circuit, MCU detection circuit, isolation module circuit, BOOST boost isolation circuit, CAN communication module, second-order filtering circuit, isolation sampling circuit, and operational amplifier differential sampling circuit.

[0014] Preferably, the isolated power supply circuit supplies power to the MCU circuit through the isolation module to separate the high and low voltage systems, the BOOST boost isolation circuit and the voltage divider sampling circuit are connected to the microprocessor, and the MCU circuit sends instructions through the communication module to control the BOOST boost isolation circuit to generate a DC24V to DC100V isolated power supply voltage, and the DC100V isolated power supply voltage is the power supply for the voltage divider sampling circuit, wherein the GND in the DC100V is connected to the casing to form a separate loop in the system.

[0015] Preferably, the isolation module circuit is converted from 24V power supply to isolated power supply 5V power supply, and the voltage standards generated are +5V1 and GND1, which is mainly used to power the insulating sampling chip while ensuring the isolation and safety of the high voltage GND1 and the MCU power supply voltage SGND.

[0016] Preferably, in the insulation detection circuit of the DC positive pole to the housing, 6 parallel and 6 series resistors are connected to test point A in the DC100V isolated power supply, and test point A is then connected to test point B through a fixed resistor R13, and test point B is short-circuited with GND1 at the same time. GND1 is connected to the high-voltage DC positive pole through a resistor R14 through a positive pole switching circuit, and then connected in series with an insulation resistor R16 between the high-voltage insulation detection positive pole and the housing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the housing. Test point A is connected to the 2-pin VIN voltage value sampling of the U1 sampling chip through a resistor, and test point B is short-circuited with GND1, which is the negative power supply pole of the sampling chip U1. At this time, the sampling chip U1 can obtain the voltage value U1 at both ends of test point A and test point B through sampling. In the DC100V insulation sampling circuit loop, R16 is the DC positive terminal insulation resistance value which is an unknown number, and other resistors are fixed resistors. The insulation resistance value of R16 can be calculated through the sampling value U1.

[0017] Preferably, in the insulation detection circuit of the DC negative pole to the housing, 6 parallel and 6 series resistors are connected to the test point C in the DC100V isolated power supply, and the test point C is then connected to the test point D through the fixed resistor R33, and the test point D is short-circuited with GND1 at the same time. The GND1 is connected to the high-voltage DC negative pole through the resistor R33 through the negative pole switching circuit, and then connected in series with the insulation resistor R34 between the high-voltage insulation detection negative pole and the housing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the housing. Test point A is connected to the 2-pin VIN voltage value sampling of the U2 sampling chip through a resistor, and the test point D is short-circuited with GND1, and GND1 is the power supply negative pole of the sampling chip U2. At this time, the sampling chip U2 can obtain the voltage value U2 at both ends of the test point C and the test point D through sampling. In the DC100V negative insulation sampling circuit loop, R36 is the DC negative terminal insulation resistance value which is an unknown number, and the other resistors are fixed resistors. The insulation resistance value of R36 can be calculated through the sampling value U2.

[0018] Preferably, when the insulation resistance between the AC live wire and the housing is detected, a 6-parallel and 6-series resistor is connected to the test point E in the DC100V isolated power supply, and the test point E is then connected to the test point F through the fixed resistor R33, and the test point F is short-circuited with GND1 at the same time. The GND1 is connected to the AC live wire through the resistor R54 through the AC live wire switching circuit, and then connected in series through the insulation resistor R56 between the AC live wire and the housing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the housing. The test point E is filtered out of the AC cosine wave signal in the DC voltage through the second-order filtering circuit to obtain a pure DC signal connected to the 2-pin VIN voltage value of the U3 sampling chip for sampling, and the test point F is short-circuited with GND1, and GND1 is the negative power supply electrode of the sampling chip U3. At this time, the sampling chip U3 can obtain the voltage value U3 at both ends of the test point E and the test point F through sampling. In the DC100V AC live wire insulation sampling circuit loop, R56 is the insulation resistance value of the AC live wire end and is an unknown number. Other resistors are fixed resistors. The insulation resistance value of R56 can be calculated through the sampling value U3.

[0019] Preferably, the second-order filtering circuit is only used in AC live wire insulation sampling. First, a first-order filtering circuit is formed by resistor R80 and capacitor C4, and then a second-order filtering circuit is formed by resistor R81 and capacitor C5. A complete filtering circuit can be formed to filter the AC signal into a pure DC signal.

[0020] Preferably, the MCU control circuit comprises three IO pins, CTL1, CTL2, and CTL3, wherein the three IO pins are interlocked, and any two IO pins cannot be at a high level at the same time; when any one IO pin is at a high level, the other two IO pins are at a low level.

[0021] Preferably, in the DC positive switching circuit, the MCU control circuit IO pin CTL1 controls the MOS tube gate to ensure that the high-voltage DC positive pole at pin 15 in the high-voltage relay K1 is connected to or disconnects the isolated power supply module GND1 at pin 13 in K1, and GND1 is connected in series to the DC100V isolated power supply circuit through a resistor.

[0022] Preferably, in the DC negative pole switching circuit, the MCU control circuit IO pin CTL2 controls the MOS tube gate to ensure that the high-voltage DC positive pole at pin 15 of the high-voltage relay K2 is connected to or disconnects the isolated power supply module GND1 at pin 13 of K2, and GND1 is connected in series to the DC100V isolated power supply circuit through a resistor.

[0023] Preferably, in the AC live wire switching circuit, the MCU control circuit IO pin CTL3 controls the MOS tube gate to ensure that the high-voltage DC positive pole at pin 15 of the high-voltage relay K3 is connected to or disconnects the isolated power supply module GND1 at pin 13 of K3, and GND1 is connected in series to the DC100V isolated power supply circuit through a resistor.

[0024] Preferably, in the isolated sampling circuit, the voltages U1 and U2 at both ends of the insulated positive and negative insulation detection circuit and the voltage U3 at both ends of the test point in the AC live wire insulation detection circuit are connected in series to the isolated voltage sampling chip through resistors, wherein the sampling chip pins 1 and 4 are powered by the isolated voltage module, where the high voltage end is connected, and the sampling chip pins 5 and 8 are powered by the MCU power supply, where the low voltage is connected. The U1, U2, and U3 sampling voltages are transmitted to the 6th and 7th pins of the chip through the chip 1:1, and then directly connected to the ADC sampling port in the MCU chip through the differential op amp sampling circuit.

[0025] Preferably, the differential sampling circuit is mainly connected to the isolated sampling voltage chip. After the voltage is output to the differential circuit, it is transmitted to the ADC detection port of the MCU through a resistor of 1:1. The voltage passing through the differential sampling circuit is more stable and will not be affected by external electromagnetic interference, and denoising processing is performed.

[0026] Preferably, the CAN communication module mainly provides sound and light alarm prompts when the insulation resistance value is abnormal.

[0027] (III) Beneficial effects

[0028] Compared with the prior art, the present invention provides a method for detecting AC and DC insulation in an energy storage system, which has the following beneficial effects:

[0029] The AC / DC insulation detection method in the energy storage system can detect not only the DC side but also the AC side. The independent power supply detection of the present invention can detect the high-voltage AC / DC insulation resistance at the same time. Whether there is high voltage or not, the system can be tested for insulation. The sampled data is accurate and the sampling response is fast. The sampling time can be set and the detection is performed before power-on to ensure the safety of equipment use and the safety of personal and property. The present invention can be modularly integrated, small in size, and cost-reduced. The problem of system insulation detection accuracy is solved and the problem of insulation detection requiring high voltage is solved. The present invention can be used in various high and low voltage working environments in industry and commerce and is suitable for various voltage types. The present invention can be used in various high and low voltage working environments in industry and commerce and is suitable for various voltage types. The present invention can detect the insulation resistance of the system at any time to ensure the safe operation of the equipment and personal safety. The sampling data of the present invention is accurate when in use because the sampling circuit uses an independent module power supply for sampling and does not use the original bus voltage for sampling, so inaccurate sampling results will not be caused by voltage fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the overall frame structure of insulation resistance sampling in an AC / DC insulation detection method system in an energy storage system proposed by the present invention;

[0031] Figure 2 A schematic diagram of the DC positive insulation resistance sampling circuit structure of an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0032] Figure 3 A schematic diagram of the DC negative electrode insulation resistance sampling circuit structure of an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0033] Figure 4 A schematic diagram of the AC live wire insulation resistance sampling circuit structure of an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0034] Figure 5 A schematic diagram of the structure of a BOOST boost isolated power supply circuit in an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0035] Figure 6 A schematic diagram of a detection circuit structure of an operational amplifier differential method for AC / DC insulation detection in an energy storage system proposed by the present invention;

[0036] Figure 7 A schematic diagram of the structure of a second-order filter circuit for AC insulation resistance sampling in an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0037] Figure 8 A schematic diagram of the structure of an electrical control circuit for detecting the insulation of the positive pole of a DC power supply in an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0038] Fig. 9 A schematic diagram of the structure of an electrical control circuit for detecting the insulation of the negative pole of a DC power supply in an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0039] Fig.10 A schematic diagram of the structure of an AC live wire insulation detection circuit of an AC / DC insulation detection method in an energy storage system proposed by the present invention;

[0040] Fig.11 A simplified block diagram of a DC positive insulation detection method in an energy storage system proposed by the present invention;

[0041] Fig.12 A simplified block diagram of a DC negative pole insulation detection method in an energy storage system proposed by the present invention;

[0042] Fig.13 A simplified block diagram of an AC / DC insulation detection method and an AC live wire insulation detection method in an energy storage system proposed by the present invention. DETAILED DESCRIPTION

[0043] 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.

[0044] See also Figure 1-13 , specific embodiment 1:

[0045] The AC and DC insulation resistance detection device in the PCS system of the energy storage system, such as Figure 1 As shown, it includes AC / DC insulation detection system, insulation detection circuit of DC positive pole to casing, insulation detection of DC negative pole to casing, insulation resistance detection of AC live wire and casing, DC positive and negative pole AC live wire switching circuit, isolated power supply circuit, MCU circuit, isolation module, BOOST boost isolation circuit, CAN communication module, second-order filtering circuit, voltage divider sampling circuit, isolation sampling circuit, operational amplifier differential sampling circuit, wherein the control power can be provided by peripheral equipment.

[0046] The power control circuit supplies power to the MCU circuit through the isolation module. The BOOST boost isolation circuit and the voltage-dividing sampling circuit are connected to the microprocessor. The MCU circuit sends instructions through the CAN communication module to control the BOOST boost isolation circuit to generate a DC24V to DC100V isolated power supply voltage. The DC100V isolated power supply voltage is the power supply for the voltage-dividing sampling circuit. The GND in the DC100V is connected to the casing to form a separate loop in the system. The DC100V power supply has a certain voltage resistance, which can ensure the system voltage resistance requirements.

[0047] like Figure 2As shown in the figure, it is the overall block diagram for testing the insulation resistance between the DC positive pole and the housing. DC100V belongs to the isolated power supply voltage, where R1 is connected in parallel with R7, R2 is connected in parallel with R8, R3 is connected in parallel with R9, R4 is connected in parallel with R10, R5 is connected in parallel with R11, and R6 is connected in parallel with R12. Then, they are connected in series to the test point A. The test point A is connected to one end of the resistor R13, and the other end of R13 is connected to GND1. GND1 is short-circuited with the test point B, and GND1 is connected to the DC positive pole of the other contact of the high-voltage relay K1 through the resistor R14, where R16 is the insulation resistance between the DC positive pole and the housing. At this time, a complete loop is formed from DC100V to DC100V_GND, and the voltages at the two ends of the test points A and B can be sampled by the chip, and the resistance value of the insulation resistor R16 can be calculated by the sampled voltage. At the same time, test point A is connected to one end of R15, and the other end of R15 is connected to pin 2 of U1 chip. Pin 1 of U1 chip is connected to the isolated power supply +5V1 power supply, and pins 3 and 4 of U1 chip are connected to GND1. At this time, the voltages at the two ends of test point A and test point B can be detected by chip U1. Pins 8 and 1 of U1 chip are connected to the 5V power supply in the control power supply, and pin 6 of U1 chip is connected to one end of resistor R17, and the other end is connected to the reverse end of pin 4 of the op amp. Pin 7 of U1 chip is connected to one end of resistor R18, and the other end is connected to the positive end of pin 3 of op amp U2. The positive end of pin 3 of op amp U2 is connected to one end of resistor R20, and the other end of R20 is connected to SGND. The reverse end of pin 4 of op amp U2 is connected to one end of resistor R21, and the other end of resistor R21 is connected to pin 1 of U2. Pin 1 of op amp U2 is connected to one end of resistor R19, and the other end of R19 is directly connected to ADC1 and one end of capacitor C1, and the other end of capacitor C1 is connected to SGND. The differential sampling circuit voltage constructed in this way is anti-interference in the sampling voltage, and the filtering processing voltage value sampling is more accurate and stable.

[0048] like Figure 3As shown in the figure, it is the overall block diagram for testing the insulation resistance between the DC negative pole and the housing. DC100V belongs to the isolated power supply voltage, where R20 is connected in parallel with R26, R21 is connected in parallel with R27, R22 is connected in parallel with R28, R23 is connected in parallel with R30, R24 is connected in parallel with R31, and R25 is connected in parallel with R32. Then, they are connected in series to the test point C. The test point C is connected to one end of the resistor R33, and the other end of R33 is connected to GND1. GND1 is short-circuited with the test point D, and GND1 is connected to the DC negative pole of the high-voltage relay K2 through the resistor R34, where R36 is the insulation resistance between the DC negative pole and the housing. At this time, a complete loop is formed from DC100V to DC100V_GND. The voltages at the two ends of the test point C and the test point D can be sampled by the chip, and the resistance value of the insulation resistor R36 can be calculated by the sampled voltage. At the same time, test point C is connected to one end of R35, and the other end of R35 is connected to pin 2 of U2 chip. Pin 1 of U2 chip is connected to the isolated power supply +5V1 power supply, and pins 3 and 4 of U2 chip are connected to GND1. At this time, the voltage at the two ends of test point C and test point D can be detected by chip U1. Pins 8 and 1 of U2 chip are connected to the 5V power supply in the control power supply, and pin 6 of U2 chip is connected to one end of resistor R38, and the other end is connected to the reverse end of pin 4 of op amp. Pin 7 of U4 chip is connected to one end of resistor R37, and the other end is connected to the positive end of pin 3 of op amp U4. The positive end of pin 3 of op amp U4 is connected to one end of resistor R38, and the other end of R38 is connected to SGND. The reverse end of pin 4 of op amp U4 is connected to one end of resistor R40, and the other end of resistor R40 is connected to pin 1 of U4. Pin 1 of op amp U4 is connected to one end of resistor R41, and the other end of R41 is directly connected to ADC2 and one end of capacitor C2, and the other end of capacitor C2 is connected to SGND. The differential sampling circuit voltage constructed in this way is anti-interference for the sampling voltage, and the filtering processing sampling value will be more accurate and stable.

[0049] like Figure 4As shown in the figure, it is the overall block diagram for testing the insulation resistance between the AC live wire and the housing. DC100V belongs to the isolated power supply voltage, where R42 is connected in parallel with R48, R43 is connected in parallel with R49, R44 is connected in parallel with R50, R45 is connected in parallel with R51, R46 is connected in parallel with R52, R47 is connected in parallel with R53, and then two are connected in series to the test point E. The test point E is connected to one end of the resistor R54, and the other end of R54 is connected to GND1. GND1 is short-circuited with the test point F, and GND1 is connected to the DC negative pole of the high-voltage relay K3 through the resistor R55, where R56 is the insulation resistance between the AC live wire and the housing. At this time, a complete loop is formed from DC100V to DC100V_GND, and the voltages at the two ends of the test points E and F can be sampled by the chip, and the resistance value of the insulation resistor R56 can be calculated by the sampled voltage. At this time, since the DC signal contains an AC signal, filtering is required. Test point C is connected to one end of R35, and the other end of R35 is connected to the input end of the second-order filter circuit. The output end of the second-order filter circuit is connected to pin 2 of the U5 chip. The second-order filter circuit is connected in series to the entire loop to filter and eliminate the AC signal. Pin 1 of the U5 chip is connected to the isolation power supply +5V1 power supply, and pins 3 and 4 of the U5 chip are connected to GND1. At this time, the voltages at the two ends of test points E and F can be detected by chip U5. Pins 8 and 1 of the U5 chip are connected to the 5V power supply in the control power supply. Pin 6 of the U5 chip is connected to one end of resistor R59, and the other end is connected to the reverse end of pin 4 of the op amp. Pin 7 of the U5 chip is connected to one end of resistor R58, and the other end is connected to the positive end of pin 3 of the op amp U6. The positive end of pin 3 of the op amp U6 is connected to one end of resistor R60, and the other end of R60 is connected to SGND. The reverse end of pin 4 of op amp U6 is connected to one end of resistor R61, the other end of resistor R61 is connected to pin 1 of U6, pin 1 of op amp U6 is connected to one end of resistor R62, the other end of R62 is directly connected to ADC3 and one end of capacitor C3, and the other end of capacitor C3 is connected to SGND. The differential sampling circuit voltage constructed in this way is anti-interference for sampling voltage, and the sampling value of filtering processing will be more accurate and stable.

[0050] like Figure 5As shown, the BOOST boost isolation power supply circuit is the main part of the PCS equipment detection system. The CN1 connector is connected to the 24V input, the ceramic capacitors C1 and C2 are connected to the 24V positive pole at one end, the 24V negative pole at one end, the 24V positive pole is connected to one end of the inductor L1, and the other end is connected to the anode of the diode D1. The anode of the diode outputs DC100V. Pin 1 of the power chip U1 is connected to the anode of the diode D1, pin 2 is connected to the 24V power supply GND, pin 3 is the feedback pin connected to DC100_GND, and pin 4 is the control pin of the boost circuit, which can be used for control. The resistors R1 and R2 in the circuit are connected in series. One end of R1 is connected to the positive pole of the output DC100V, and one end of R2 is connected to DC100V_GND. The main function is to perform feedback protection. When the voltage exceeds the preset value, it will automatically protect itself. One end of the ceramic capacitors C3 and C4 is connected to the positive pole of DC100V and the other end is connected to the negative pole of DC100V_GND for filtering. The DC100V power supply voltage is an independent isolation voltage, in which DC100V_GND is short-circuited with the casing, mainly to form a voltage loop, and the DC100V isolated power supply has a certain voltage resistance, and will not produce voltage fluctuations due to the influence of the system, and the sampling value will be more accurate.

[0051] like Figure 6 As shown, it is a differential operational amplifier circuit diagram applicable to the entire insulation detection, which is used for DC positive, DC negative, and AC live wire insulation sampling detection of the chassis. The voltages VIN+ and VIN- pass through the operational amplifier U1. Pins 2 and 5 of the operational amplifier are respectively powered by 5V of the isolated power supply. Pin 3 is connected to the input voltage VIN- after being connected to the series resistor R2, and is grounded after being connected to the series resistor R4. Pin 4 is connected to the input voltage VIN+ after being connected to the series resistor R1. The output voltage is connected to the series resistor R5 at pin 1 of the operational amplifier, forming a differential discharge circuit. The output voltage is pin 1 of the operational amplifier. The output voltage of pin 1 passes through R3 to form a protection connection to the ADC1 pin of the MCU for sampling voltage.

[0052] like Figure 7As shown in the figure, it is a second-order filter circuit diagram in AC live wire insulation detection. At this time, the sampled voltage contains AC cosine wave noise. Unlike DC, filtering is required here. At this time, the second-order filter circuit can filter out the influence of the cosine wave on the sampled voltage. As shown in the figure, pin 1 of U10 is the output voltage of the operational amplifier and short-circuited with the positive feedback of pin 3. Pin 4 of U10 is connected to one end of the series resistor R81, and the other end of R81 is connected to one end of R80, and the other end of R80 is connected to the cathode of diode D7. R80 and capacitor C4 form a first-order filter circuit, and R81 metal film resistor and electrolytic capacitor C5 form a second-order filter circuit. The cathode of diode D4 is connected to R80 and the connection end with R81, the anode of diode D4 is connected to the anode of diode D5, and the cathode of diode D5 is connected to pin 1 of switching diode D6. Pin 3 of switching diode D6 is connected to the positive end of pin 4 of operational amplifier U10, and pin 2 is connected to the power supply +5V. The circuit composed of D4, D5, and D6 can not only effectively protect the operational amplifier U10 from the influence of the AC signal, but also can effectively filter and eliminate the cosine wave with the second-order filter circuit, making the sampling value more stable.

[0053] like Figure 8 As shown, it is a DC positive insulation detection switching circuit. CTL1 controls the signal. The series resistor R70 controls whether the MOS tube Q1 is turned on. When CTL1 is at a high level, the MOS tube is turned on, the DC relay K1 is energized, and the DC positive series resistor R73 is connected to the GND1 test point. GND1 is the negative power supply of the sampling chip. When K1 is energized, Fig. 9 , Fig.10 K2 and K2 in the circuit are not energized. The purpose is not only to detect the insulation resistance of the DC positive pole, but also to avoid short circuit.

[0054] like Fig. 9 As shown, it is a DC negative pole insulation detection switching circuit. CTL2 controls the signal. The series resistor R74 controls whether the MOS tube Q2 is turned on. When CTL2 is at a high level, the MOS tube is turned on, the DC relay K2 is energized, and the DC negative pole series resistor R76 is connected to the GND1 test point. GND1 is the negative power supply pole of the sampling chip. When K2 is energized, Figure 8 , Fig.10 K1 and K2 in the circuit are not energized, so as to detect the insulation resistance of the DC negative pole without causing a short circuit.

[0055] like Fig.10 As shown in the figure, it is an AC live wire insulation detection switching circuit. CTL3 controls the signal, and the series resistor R77 controls whether the MOS tube Q3 is turned on. When CTL3 is at a high level, the MOS tube is turned on, and the AC relay K3 is energized. The AC live wire series resistor R79 is connected to the GND1 test point. GND1 is the negative power supply of the sampling chip. When K3 is energized, Figure 8, Fig. 9 K1 and K2 in the circuit are not energized, so as to detect the insulation resistance of the AC live wire without causing a short circuit.

[0056] The relay selected in the system is a high-voltage resistant relay, and has an interlocking function when controlled by MCU, which prevents the relays from being controlled simultaneously. Through the above, the insulation resistance of the positive and negative poles of the DC of the PCS in the energy storage system can be detected, as well as the insulation detection of L in the AC. Specific embodiment 2:

[0058] The above insulation detection system can be compared with the AC and DC system insulation detection method of PCS equipment. The above is a specific scheme for the insulation resistance detection of each circuit of the PCS system, and the AC and DC insulation detection method. The specific steps are as follows:

[0059] 1: Detect the insulation resistance of the positive pole of the DC voltage to the housing, such as Fig.11 As shown, when the high-voltage relay K1 is energized, a DC100V circuit is formed, in which the voltage U1 at points A and B at both ends of R101 is the sampling voltage.

[0060] I1=100V / (R100+R101+R102+R103),

[0061] U1=R101×I1

[0062] U1=R101 / (R100+R101+R102+R103)×100V

[0063] At this time, U1 can obtain a specific value from the sampling chip, R100, R101, and R102 are fixed resistance values, and R103 is the insulation resistance value that needs to be calculated.

[0064] So: R103 = R101 × 100V / U1-R100-R101-R102

[0065] It can be calculated that the insulation resistance value of the DC positive electrode is R103

[0066] 2: Detect the insulation resistance of the negative pole of the DC voltage to the housing, such as Fig.12 As shown, when the high-voltage relay K2 is energized, a DC100V circuit is formed, in which the voltage U2 at points C and D at both ends of R107 is the sampling voltage.

[0067] I2=100V / (R106+R107+R108+R104),

[0068] U2=R107×I1

[0069] U2=R107 / (R106+R107+R108+R104)×100V

[0070] At this time, U2 can obtain a specific value from the sampling chip, R106, R107, and R108 are fixed resistance values, and R104 is the insulation resistance value that needs to be calculated.

[0071] So: R104 = R107 × 100V / U2-R106-R107-R108

[0072] It can be calculated that the insulation resistance value of the DC negative pole is R104

[0073] 3: Check the insulation resistance of the AC live wire to the housing, such as Fig.13 As shown, when the high-voltage relay K3 is energized, a DC100V circuit is formed, in which the voltage U3 at points E and F at both ends of R113 is the sampling voltage.

[0074] I3=100V / (R112+R113+R114+R105),

[0075] U3=R113×I1

[0076] U3=R113 / (R112+R113+R114+R105)×100V

[0077] At this time, U3 can obtain a specific value from the sampling chip, R112, R113, and R114 are fixed resistance values, and R105 is the insulation resistance value that needs to be calculated.

[0078] So: R105 = R107 × 100V / U2-R106-R107-R108

[0079] It can be calculated that the insulation resistance value of the AC live wire is R105

[0080] In the above, when the insulation resistance of R103, R104, and R105 tends to +∞, if the insulation resistance value of the sampling value of U1, U2, and U3 does not meet the set conditions, the sampling values ​​of the sampling voltages U2, U3, and U4 are different, and an audible and visual alarm can be given through the MCU control circuit. If the insulation resistance value is small enough, the circuit protection can be directly performed through the MCU control circuit. The present invention can detect the insulation resistance value at any time, has a small size, and has accurate sampling data.

[0081] The above is a preferred embodiment of the sampling of the present invention on PCS, and is not any form of limitation on the present invention. Although the present invention has been disclosed as above in the preferred embodiment, it does not limit the invention to only a specific implementation method. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

[0082] The electrical components mentioned in this article are all connected to an external main controller and 220V mains electricity, and the main controller can be a conventional known device for controlling a computer or the like.

[0083] In summary, the AC / DC insulation detection method in the energy storage system, when in use, can not only detect the DC, but also perform insulation detection on the AC side. The sampling independent power supply detection of the present invention can simultaneously detect the high-voltage AC / DC insulation resistance. Whether there is high voltage or not, the system can be insulation-detected, and the sampled data is accurate, the sampling response is fast, the sampling time can be set, and the detection is performed before power-on to ensure the safety of equipment use and the safety of personal and property. The present invention can be modularly integrated, small in size, and cost-reduced, and solves the problem of system insulation detection accuracy, and solves the problem that insulation detection must be performed with high voltage. The present invention can be used in various high and low voltage working environments in industry and commerce, and is suitable for various voltage types. The present invention can be used in various high and low voltage working environments in industry and commerce, and is suitable for various voltage types. The present invention can detect the insulation resistance of the system at any time, ensuring the safe operation of the equipment and personal safety. The sampling data of the present invention is accurate when in use, because the sampling circuit is an independent module power supply for sampling, and the original bus voltage is not used for sampling, and the sampling result will not be inaccurate due to voltage fluctuations.

[0084] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise one" do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0085] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting AC and DC insulation in an energy storage system. Features: The following steps are involved: Step 1: Regularly test the insulation resistance of high-voltage DC and AC inside the PCS to ensure normal operation of the equipment and personal safety; Step 2: By controlling the detection voltage, the relay can be switched to detect the insulation resistance of the DC positive and negative poles to the casing, the DC negative pole to the casing, and the AC live wire to the casing; Step 3: The energy storage AC / DC insulation detection system circuit includes: insulation detection circuit of DC positive pole to casing, insulation detection of DC negative pole to casing, insulation resistance detection of AC live wire and casing, DC positive and negative pole AC live wire switching circuit, isolated power supply circuit, MCU detection circuit, isolation module circuit, BOOST boost isolation circuit, CAN communication module, second-order filtering circuit, voltage divider sampling circuit, isolation sampling circuit, and operational amplifier differential sampling circuit.

2. A method for detecting AC and DC insulation in an energy storage system according to claim 1, Features: The isolated power supply circuit supplies power to the MCU circuit through the isolation module to separate the high and low voltage systems. The BOOST boost isolation circuit and the voltage-dividing sampling circuit are connected to the microprocessor. The MCU circuit sends instructions through the communication module to control the BOOST boost isolation circuit to generate a DC24V to DC100V isolated power supply voltage. The DC100V isolated power supply voltage is the power supply for the voltage-dividing sampling circuit, wherein the GND in the DC100V is connected to the casing to form a separate loop in the system.

3. The AC / DC insulation detection method in an energy storage system according to claim 2, Features: In the insulation detection circuit of the DC positive electrode to the casing, 6 parallel and 6 series resistors are connected to the test point A in the DC100V isolated power supply, and the test point A is then connected to the test point B through the fixed resistor R13, and the test point B is short-circuited with GND1. The GND1 is connected to the high-voltage DC positive electrode through the resistor R14 through the positive switching circuit, and then connected in series with the insulation resistor R16 between the high-voltage insulation detection positive electrode and the casing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the casing, and the test point A is connected to the 2-pin VIN voltage value sampling of the U1 sampling chip through a resistor, and the test point B is short-circuited with GND1, and GND1 is the negative power supply electrode of the sampling chip U1. At this time, the sampling chip U1 can obtain the voltage value U1 at both ends of the test point A and the test point B through sampling.

4. The AC / DC insulation detection method in an energy storage system according to claim 3, Features: In the insulation detection circuit of the DC negative pole to the casing, 6 parallel and 6 series resistors are connected to the test point C in the DC100V isolated power supply, and the test point C is then connected to the test point D through the fixed resistor R33, and the test point D is short-circuited with GND1. The GND1 is connected to the high-voltage DC negative pole through the resistor R33 through the negative pole switching circuit, and then connected in series with the insulation resistor R34 between the high-voltage insulation detection negative pole and the casing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the casing, and the test point A is connected to the 2-pin VIN voltage value sampling of the U2 sampling chip through a resistor, and the test point D is short-circuited with GND1, and GND1 is the power supply negative pole of the sampling chip U2. At this time, the sampling chip U2 can obtain the voltage value U2 at both ends of the test point C and the test point D through sampling.

5. The AC / DC insulation detection method in an energy storage system according to claim 4, Features: When the insulation resistance between the AC live wire and the casing is detected, 6 parallel and 6 series resistors are connected to the test point E in the DC100V isolated power supply, and the test point E is then connected to the test point F through the fixed resistor R33. At the same time, the test point F is short-circuited with GND1, and the GND1 is connected to the AC live wire through the resistor R54 through the AC live wire switching circuit, and then connected in series through the insulation resistor R56 between the AC live wire and the casing, thereby forming a DC100V to DC100V_GND loop, wherein DC100V_GND is short-circuited with the casing, and the test point E is filtered out the AC cosine wave signal in the DC voltage through the second-order filtering circuit to obtain a pure DC signal connected to the 2-pin VIN voltage value of the U3 sampling chip for sampling, and the test point F is short-circuited with GND1, and GND1 is the negative power supply electrode of the sampling chip U3. At this time, the sampling chip U3 can obtain the voltage value U3 at both ends of the test point E and the test point F through sampling.

6. A method for detecting AC and DC insulation in an energy storage system according to claim 5, Features: In the insulation detection circuit of the DC positive electrode to the casing, DC100V belongs to the isolated power supply voltage, wherein R1 is connected in parallel with R7, R2 is connected in parallel with R8, R3 is connected in parallel with R9, R4 is connected in parallel with R10, R5 is connected in parallel with R11, R6 is connected in parallel with R12, and then two of them are connected in series to the test point A, the test point A is connected to one end of the resistor R13, the other end of R13 is connected to GND1, GND1 is short-circuited with the test point B, GND1 is connected to the DC positive electrode of the other contact of the high-voltage relay K1 through the resistor R14, wherein R16 is the insulation resistance between the DC positive electrode and the casing, at this time, a complete loop is formed from DC100V to DC100V_GND, the voltages at the two ends of the test point A and the test point B can be sampled by the chip, and the resistance value of the insulation resistor R16 can be calculated by the sampled voltage, and at the same time, the test point A is connected to one end of R15, R15 The other end is connected to pin 2 of U1 chip, pin 1 of U1 chip is connected to the isolated power supply +5V1, pins 3 and 4 of U1 chip are connected to GND1, at this time, the voltage at the two ends of test point A and test point B can be detected by chip U1, pins 8 and 1 of U1 chip are connected to the 5V power supply in the control power supply, pin 6 of U1 chip is connected to one end of resistor R17, and the other end is connected to the reverse end of pin 4 of the op amp, pin 7 of U1 chip is connected to one end of resistor R18, and the other end is connected to the positive end of pin 3 of op amp U2, the positive end of pin 3 of op amp U2 is connected to one end of resistor R20, and the other end of R20 is connected to SGND, the reverse end of pin 4 of op amp U2 is connected to one end of resistor R21, and the other end of resistor R21 is connected to pin 1 of U2, pin 1 of op amp U2 is connected to one end of resistor R19, the other end of R19 is directly connected to ADC1 and one end of capacitor C1, and the other end of capacitor C1 is connected to SGND.

7. The AC / DC insulation detection method in an energy storage system according to claim 5, Features: In the insulation detection circuit of the DC negative electrode to the casing, R20 is connected in parallel with R26, R21 is connected in parallel with R27, R22 is connected in parallel with R28, R23 is connected in parallel with R30, R24 is connected in parallel with R31, and R25 is connected in parallel with R32, and then two of them are connected in series to the test point C, the test point C is connected to one end of the resistor R33, the other end of R33 is connected to GND1, GND1 is short-circuited with the test point D, and GND1 is connected to the DC negative electrode of the high-voltage relay K2 through the resistor R34, wherein R36 is the insulation resistance between the DC negative electrode and the casing, and at this time a complete loop is formed from DC100V to DC100V_GND, the voltages at the two ends of the test point C and the test point D can be sampled by the chip, and the resistance value of the insulation resistor R36 can be calculated by the sampled voltage, and at the same time, the test point C is connected to one end of R35, and the other end of R35 is connected to Pin 2 of U2 chip and pin 1 of U2 chip are connected to the isolated power supply +5V1, pins 3 and 4 of U2 chip are connected to GND1, at this time, the voltage at the two ends of test point C and test point D can be detected by chip U1, pins 8 and 1 of U2 chip are connected to the 5V power supply in the control power supply, pin 6 of U2 chip is connected to one end of resistor R38, and the other end is connected to the reverse end of pin 4 of op amp, pin 7 of U4 chip is connected to one end of resistor R37, and the other end is connected to the positive end of pin 3 of op amp U4, the positive end of pin 3 of op amp U4 is connected to one end of resistor R38, and the other end of R38 is connected to SGND, the reverse end of pin 4 of op amp U4 is connected to one end of resistor R40, and the other end of resistor R40 is connected to pin 1 of U4, pin 1 of op amp U4 is connected to one end of resistor R41, and the other end of R41 is directly connected to ADC2 and one end of capacitor C2, and the other end of capacitor C2 is connected to SGND.

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