Energy storage converter insulation resistance detection circuit and detection method

Abstract

The present invention belongs to the technical field of electronic circuits, and discloses an energy storage converter insulation resistance detection circuit and detection method. The circuit includes a signal acquisition circuit, a signal processing circuit, a relay drive circuit and a microcontroller. In the signal acquisition circuit, one end of the first resistance unit is connected to the positive bus, and the other end is connected to one end of the second resistance unit; the other end of the second resistance unit is connected to the negative bus through the third resistance unit; one end of the relay switch K1 is connected to the other end of the second resistance unit, and the other end is grounded; one end of the relay switch K2 is connected to one end of the first resistance unit, and the other end is connected to the negative bus; the voltage at both ends of the third resistance unit is sent to the microcontroller after the signal processing circuit. The present invention has comprehensive detection capabilities and high accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits, and in particular relates to an insulation resistance detection circuit and a detection method for an energy storage converter. Background Art

[0002] In order to ensure the safety of equipment and personnel, energy storage converters are usually equipped with insulation detection circuits. Insulation resistance is a key indicator for measuring the insulation performance of electrical systems, and is particularly important for the insulation status of the battery pack and the DC side of the converter in the energy storage system. The insulation detection circuit can monitor the insulation status in real time, detect the aging or damage of the insulation material in time, prevent electrical fires, equipment damage and electric shock hazards, and ensure the safe and stable operation of the system.

[0003] Among the existing detection methods, the balanced bridge method and the unbalanced bridge method are two commonly used detection methods. In the balanced bridge method, a larger detection resistor is connected in parallel to the positive insulation resistance and the negative insulation resistance respectively. When the insulation resistance on one side becomes low, the voltage on that side will be quickly lowered, so that the fault and resistance value can be detected. The defect of this method is that it cannot identify the fault when the bipolar insulation resistance drops equally to the ground. The unbalanced bridge method changes the equivalent resistance of the two poles to the ground by alternately switching the switches on both sides, and obtains an unbalanced detection voltage on the positive and negative detection resistors, thereby calculating the insulation resistance of the positive and negative poles. The defect is that it is necessary to collect voltage signals from two places, the circuit consistency is poor, and the accuracy is reduced.

[0004] In order to solve the technical problems that the balanced bridge insulation monitoring circuit in the prior art cannot detect the equal-amplitude drop of the bipolar insulation resistance to ground, and the unbalanced bridge insulation monitoring circuit has low accuracy, it is necessary to improve the insulation monitoring circuit in the prior art. Summary of the invention

[0005] In order to solve the technical problems in the prior art that the balanced bridge insulation monitoring circuit cannot detect the equal-amplitude drop of the bipolar insulation resistance to ground, and the unbalanced bridge insulation monitoring circuit has low accuracy, the present invention provides an energy storage converter insulation resistance detection circuit and detection method.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an energy storage converter insulation resistance detection circuit, comprising: a signal acquisition circuit, a signal processing circuit, a relay drive circuit and a microcontroller, the signal acquisition circuit comprising a first resistance unit, a second resistance unit, a third resistance unit, a relay switch K1 and a relay switch K2; the first resistance unit, the second resistance unit and the third resistance unit have the same resistance value; one end of the first resistance unit is connected to the positive bus, and the other end is connected to one end of the second resistance unit; the other end of the second resistance unit is connected to the negative bus after passing through the third resistance unit; one end of the relay switch K1 is connected to the other end of the second resistance unit, and the other end is grounded; one end of the relay switch K2 is connected to one end of the first resistance unit, and the other end is connected to the negative bus; the voltage at both ends of the third resistance unit is amplified by the signal processing circuit and sent to the microcontroller;

[0007] The relay drive circuit is used to control the on and off of the relay switch K1 and the relay switch K2; the microcontroller is used to calculate the magnitude of the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 according to the measured voltage across the third resistance unit.

[0008] The calculation formula of positive electrode insulation resistance R1 and negative electrode insulation resistance R2 is:

[0009]

[0010] Wherein, U1 represents the voltage across the third resistor unit when the relay switch K1 is closed and the relay switch K2 is open, U2 represents the voltage across the third resistor unit when both the relay switch K1 and the relay switch K2 are closed, R represents the resistance values ​​of the first resistor unit, the second resistor unit, and the third resistor unit, and U B Indicates the DC bus voltage.

[0011] The first resistance unit, the second resistance unit and the third resistance unit each include a plurality of resistors connected in series.

[0012] The first resistance unit includes resistors R20, R21, R22, R23, R24, and R25 connected in series in sequence, the second resistance unit includes resistors R26, R27, R28, R29, R30, and R31 connected in series in sequence, and the third resistance unit includes resistors R32, R33, R34, R36, R37, and R38 connected in series in sequence.

[0013] The third resistance unit further includes a protection resistor R35, which is arranged in series in the branch where the third resistance unit is located and is located at the resistance center of the third resistance unit; the signal processing circuit includes an operational amplifier U6D, a resistor R192, a resistor R195, a capacitor C96, and a capacitor C98;

[0014] The reverse input terminal of the operational amplifier U6D is connected to one end of the protection resistor R35 close to the ground terminal, the non-inverting input terminal is connected to one end of the protection resistor R35 close to the negative bus, the output terminal of the operational amplifier U6D is connected to the reverse input terminal through the resistor R192, and the capacitor C96 is connected in parallel with the resistor R192; one end of the resistor R195 is connected to the non-inverting input terminal of the operational amplifier U6D, and the other end is grounded, the capacitor C98 is connected in parallel with the resistor R195, and the output terminal of the operational amplifier U6D is connected to the input terminal of the microcontroller.

[0015] The signal processing circuit also includes a transient voltage suppressor TS25 and a transient voltage suppressor TS26, wherein the output port of the transient voltage suppressor TS25 is connected to the inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply;

[0016] The output port of the transient voltage suppressor TS26 is connected to the non-inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply.

[0017] The energy storage converter insulation resistance detection circuit also includes a clamping protection circuit, which includes a resistor R38, a capacitor C34, and a transient voltage suppressor TS30; the output end of the operational amplifier U6D is connected to one end of the resistor R38, the other end of the resistor R38 is connected to the input end of the microcontroller, the other end of the resistor R38 is also grounded via the capacitor C34, and the other end of the resistor R38 is also connected to the output port of the transient voltage suppressor TS30; the negative electrode of the transient voltage suppressor TS30 is connected to the positive electrode of the power supply, and the positive electrode is grounded.

[0018] The calculation formulas for voltage U1 and voltage U2 are:

[0019]

[0020]

[0021] Among them, U cp1 It represents the voltage collected by the microcontroller when the relay switch K1 is closed and the relay switch K2 is open. cp2 1 shows the voltage collected by the microcontroller when the relay switch K1 and the relay switch K2 are both closed, and R0 represents the resistance value between the end of the protection resistor R35 in the third resistor unit close to the ground end and the ground end.

[0022] The relay drive circuit includes a resistor R186, a resistor R187, a resistor R186, a resistor R187, a transistor V1, and a transistor V2; one end of the resistor R186 is connected to the first control signal output end of the microcontroller, and the other end is connected to the base of the transistor V1; one end of the resistor R188 is connected to the base of the transistor V1, and the other end is grounded; the collector of the transistor V1 is connected to one end of the coil of the relay switch K1, and the emitter of the transistor V1 is grounded; the other end of the coil of the relay switch K1 is connected to the positive electrode of the power supply, and the voltage regulator diode VD2 is connected in parallel with the coil of the relay switch K1;

[0023] One end of the resistor R187 is connected to the second control signal output end of the microcontroller, and the other end is connected to the base of the transistor V2; one end of the resistor R189 is connected to the base of the transistor V2, and the other end is grounded; the collector of the transistor V2 is connected to one end of the coil of the relay switch K2, and the emitter of the transistor V2 is grounded; the other end of the coil of the relay switch K2 is connected to the positive electrode of the power supply, and the voltage regulator diode VD1 is connected in parallel with the coil of the relay switch K2.

[0024] In addition, the present invention also provides an energy storage converter insulation resistance detection method, which is implemented based on the energy storage converter insulation resistance detection circuit, and includes the following steps:

[0025] Step 1: Initialize after power-on, and then detect the bus voltage;

[0026] Step 2: Control the relay switch K1 to be closed and the relay switch K2 to be open, and then collect the voltage U1; control the relay switch K1 and the relay switch K2 to be closed, and collect the voltage U2;

[0027] Step 3: Control the relay switch K1 and the relay switch K2 to be disconnected, and calculate the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2;

[0028] Step 4: Determine whether the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 are qualified. If qualified, end and wait for the next cycle to return to step 2 to continue controlling the relay for data collection. If unqualified, disconnect the main power relays and issue a fault alarm.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention provides an energy storage converter insulation resistance detection circuit and detection method, which has comprehensive detection capabilities, can measure the insulation resistance value under various conditions, and can adapt to the special situation where the positive and negative insulation resistances drop equally. This means that even when the resistance value changes symmetrically, the present invention can accurately capture these changes to ensure that there are no blind spots or omissions in detection.

[0031] 2. High precision: The present invention detects the voltage value at the same position through different combinations of switch modes, which can effectively eliminate the error influence caused by circuit consistency problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a circuit schematic diagram of a signal acquisition circuit in Embodiment 1 of the present invention;

[0033] Figure 2 is a circuit schematic diagram of a signal acquisition circuit in Embodiment 2 of the present invention;

[0034] Figure 3 is a circuit schematic diagram of a signal processing circuit in Embodiment 2 of the present invention;

[0035] Figure 4 is a circuit schematic diagram of a clamping protection circuit in Embodiment 2 of the present invention;

[0036] Figure 5 This is a circuit schematic diagram of the board line connector terminal in the second embodiment of the present invention;

[0037] Figure 6 is a circuit schematic diagram of a relay driving circuit in Embodiment 2 of the present invention;

[0038] Figure 7 This is a flow chart of a method for detecting insulation resistance of an energy storage converter provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in combination with specific embodiments and drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] Embodiment 1

[0041] Embodiment 1 of the present invention provides an insulation resistance detection circuit for an energy storage converter, comprising: a signal acquisition circuit, a signal processing circuit, a relay drive circuit and a microcontroller.

[0042] like Figure 1As shown, the signal acquisition circuit includes a first resistor unit R(1), a second resistor unit R(2), a third resistor unit R(3), a relay switch K1 and a relay switch K2; the first resistor unit R(1), the second resistor unit R(2) and the third resistor unit R(3) have the same resistance value; one end of the first resistor unit R(1) is connected to the positive bus, and the other end is connected to one end of the second resistor unit R(2); the other end of the second resistor unit R(2) is connected to the negative bus through the third resistor unit R(3); one end of the switch K1 is connected to the other end of the second resistor unit, and the other end is grounded; one end of the switch K2 is connected to one end of the first resistor unit, and the other end is connected to the negative bus; the voltage across the two ends of the third resistor unit is sent to the microcontroller through the signal processing circuit.

[0043] In the DC bus circuit of the energy storage converter, the two ends of the positive insulation resistor R1 are respectively connected to the positive bus P and the ground PE, and the two ends of the negative insulation resistor R2 are respectively connected to the negative bus N and the ground PE. In this embodiment, by adding three resistance branches, including a first resistance unit R(1), a second resistance unit R(2), and a third resistance unit R(3), two relays K1 and K2 are set at the same time, and the resistance values ​​of the positive insulation resistance to ground and the negative insulation resistance to ground of the energy storage converter are calculated according to the bus voltage and the voltage corresponding to the external resistance branch under different combination switching modes. When the relay switches K1 and K2 are both in the open circuit state, these three resistance branches will be connected in series with the positive and negative poles of the DC bus. The three resistance units from the positive pole to the negative pole of the DC bus are marked as R(1), R(2) and R(3) respectively. The two relay switches set in the signal acquisition circuit of this embodiment can change the series-parallel relationship of the circuit by switching the relay. When the relay K1 is closed, the circuit between R(2) and R(3) will be directly grounded. Relay K2: Located between the R(1) and R(2) resistor branches. When K2 is closed, the circuit between R(1) and R(2) will be directly connected to the negative bus.

[0044] The following describes the working process and working principle of measuring insulation resistance in an embodiment of the present invention.

[0045] (1) Bus voltage: First, measure the voltage of the DC bus, which will be the base voltage for measuring insulation resistance.

[0046] (2) Switch combination: By changing the closed or open state of relays K1 and K2, different resistance branch combinations can be created, thereby measuring the voltage values ​​on both sides of the resistance branch R(3) in different series and parallel states of the circuit.

[0047] (3) Voltage drop measurement: Measure the voltage drop across the resistance branch R(3). When K1 is closed and K2 is open, the voltage U1 is measured. When both K1 and K2 are closed, the voltage U2 is measured.

[0048] (4) Calculation of insulation resistance: Calculate the insulation resistance formula based on the relationship between resistance and voltage, and substitute the measured value to calculate the insulation resistance value.

[0049] The positive electrode insulation resistance is R1, the negative electrode insulation resistance is R2, the resistance values ​​of the three resistance units R(1), R(2), and R(3) are all R, and the collected DC bus voltage is recorded as U B , when K1 is closed and K2 is open, the voltage of the R(3) resistor branch is recorded as U1, and when both K1 and K2 relays are closed, the voltage of the R(3) resistor branch is recorded as U2. The following conclusions can be drawn:

[0050] When the relay switch K1 is closed and the relay switch K2 is open, the circuit between the resistance units R(2) and R(3) is directly grounded, and the resistance units R(1) and R(2) are connected in series and in parallel with R1. At this time, the positive electrode insulation resistance is 2R||R1; R(3) forms a parallel connection with the negative electrode insulation resistance R2. At this time, the negative electrode insulation resistance is R||R2. In the parallel circuit, the voltages of the two resistors are the same, so R(3) and R2 will have the same voltage; the measured voltage U1 (PE to N voltage) of the resistance unit R(3) is:

[0051]

[0052] When both relay switch K1 and relay switch K2 are closed, the resistor unit R(1) is directly connected to the positive bus and the negative bus through relay switch K2 without passing through the ground wire; the resistor units R(2) and R(3) are connected in parallel with R2, and the negative electrode insulation resistance is 0.5R||R2. The R(2) and R(3) resistor branches have the same voltage as R2; the above circuit is connected in series with R1, and the positive electrode insulation resistance is R1; the measured voltage U2 of the R(3) resistor branch (the voltage between PE and N) is:

[0053]

[0054] Specifically, in combination with formulas (1) to (2), it can be known that in this embodiment, the calculation formulas for the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 are:

[0055]

[0056] Wherein, U1 represents the voltage across the third resistor unit R(3) when the relay switch K1 is closed and the relay switch K2 is open, U2 represents the voltage across the third resistor unit R(3) when both the relay switch K1 and the relay switch K2 are closed, R represents the resistance values ​​of the first resistor unit, the second resistor unit, and the third resistor unit, and U B Indicates the DC bus voltage.

[0057] Therefore, in this embodiment, the relay switch K1 is controlled to be closed and the relay switch K2 is open, and then the voltage U1 is collected; the relay switch K1 and the relay switch K2 are both closed, and the voltage U2 is collected; and then combined with the above formulas (3) to (4), the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 can be measured.

[0058] Specifically, in this embodiment, the relay drive circuit is used to control the on and off of the relay switch K1 and the relay switch K2; the microcontroller is used to calculate the size of the positive insulation resistance R1 and the negative insulation resistance R2 based on the measured voltage across the third resistance unit.

[0059] Embodiment 2

[0060] The second embodiment provides an energy storage converter insulation resistance detection circuit, which is the same as the first embodiment in that it includes: a signal acquisition circuit, a signal processing circuit, a relay drive circuit and a microcontroller. The signal acquisition circuit includes a first resistance unit R (1), a second resistance unit R (2), a third resistance unit R (3), a relay switch K1 and a relay switch K2. Different from the first embodiment, in the signal acquisition circuit of the present embodiment, the first resistance unit, the second resistance unit and the third resistance unit all include a plurality of resistors connected in series.

[0061] Specifically, Figure 2 As shown, in this embodiment, the first resistance unit includes resistors R20, R21, R22, R23, R24, R25 connected in series in sequence, the second resistance unit includes resistors R26, R27, R28, R29, R30, R31 connected in series in sequence, and the third resistance unit includes resistors R32, R33, R34, R36, R37, R38 connected in series in sequence. The resistances of the branches where these three resistance units are located are also consistent. When the relays are all in the open circuit state, these resistance units will connect the positive and negative poles of the DC bus in series to form a continuous resistance path.

[0062] Since high-resistance resistors are more likely to be damaged (due to temperature and humidity, oxidation failure of metal film resistors, etc.) and there are few traces, they are not easy to detect. In this embodiment, multiple resistors are connected in series to form three resistor units, which can reduce the resistance value used in the circuit and reduce the risk of damage. In addition, a single resistor is used as a branch, and there is a risk of short circuit after damage, causing more serious impact. Therefore, in this practical application, multiple resistors are used in series to form a resistor unit, which can reduce the impact of damage.

[0063] Furthermore, if Figure 2As shown, in this embodiment, the third resistance unit also includes a protection resistor R35, and the protection resistor R35 is arranged in series at the resistance center of the third resistance unit, that is, the resistance value of the resistance on its left side is equal to the resistance value of the resistance on the right side. Specifically, in this embodiment, R32=R33=R34=R36=R37=R38, then the protection resistor R35 is connected in series between the resistor R34 and the resistor R36.

[0064] Figure 2 In the figure, BatF+ is the positive electrode of the battery bus, BatF- is the negative electrode of the battery bus, and PE is the ground terminal; PE1_1 and Ucell-1 are the voltage signals collected at both ends of the protection resistor R35. The signal is passed through Figure 5 The board line connector terminal shown is connected to a signal acquisition circuit, specifically, the signal acquisition circuit is a differential circuit.

[0065] like Figure 3 As shown, the signal processing circuit includes an operational amplifier U6D, a resistor R192, a resistor R195, a capacitor C96, and a capacitor C98; the inverting input terminal of the operational amplifier U6D is connected to one end of the protection resistor R35 close to the ground terminal, the in-phase input terminal is connected to one end of the protection resistor R35 close to the negative bus, the output terminal of the operational amplifier U6D is connected to the inverting input terminal through the resistor R192, and the capacitor C96 is connected in parallel with the resistor R192; one end of the resistor R195 is connected to the in-phase input terminal of the operational amplifier U6D, and the other end is grounded, the capacitor C98 is connected in parallel with the resistor R195, and the output terminal of the operational amplifier U6D is connected to the input terminal of the microcontroller.

[0066] Furthermore, in this embodiment, if Figure 3 As shown, the signal processing circuit also includes a transient voltage suppressor TS25 and a transient voltage suppressor TS26, wherein the output port of the transient voltage suppressor TS25 is connected to the inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply; the output port of the transient voltage suppressor TS26 is connected to the non-inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply.

[0067] In this embodiment, the two ends of the protection resistor R35 are connected to the differential circuit. According to the virtual short characteristic of the operational amplifier, the voltage values ​​at both ends of the protection resistor R35 are the same, that is, the resistor does not affect the resistance value of the entire branch. Therefore, the resistance value of the third resistor unit is only equivalent to the resistance value of the other six resistors in series, and its total resistance value is consistent with the other two resistor units.

[0068] In this embodiment, the protection resistor R35 is a protection element, and its main function is to Figure 5When the board-wire connector terminals shown are not connected, high voltage breakdown is prevented between the socket terminals. Through the intervention of the protection resistor R35, a high resistance path can be provided between the unconnected terminals to provide a current path, thereby preventing the voltage from accumulating to a level sufficient to cause arcing. Such a protection mechanism is essential to maintaining the stability of the circuit and extending its service life, while also protecting the safety of personnel and equipment using the circuit. Specifically, the signal at both ends of the protection resistor R35 passes through the board-wire connector terminals and is transmitted to another board (main board) via the wiring harness and connected to the differential circuit. When both relay switches K1 and K2 are disconnected, the current passes through R(1), R(2) and R(3) in sequence, and is divided by multiple resistors, R 35 The voltage across the resistor R35 is relatively low and there is no risk of breakdown. If there is no protective resistor and the wiring harness is not connected to the subsequent differential circuit, when the relay switches K1 and K2 are both disconnected, no current flows between PE1_1 and Ucell-1, and the voltage across the resistor R35 is U PE -U Bat F - half bus voltage, it is very likely to break down the terminal and cause arcing.

[0069] In this embodiment, the signal processing circuit is a differential circuit, which is used to process the two voltage signals obtained from the acquisition circuit to ensure that the proportional relationship between the output signal and the input signal is consistent. This operation can adjust the amplitude of the signal to a limit suitable for processing by a microcontroller (MCU). If the amplitude of the input signal is too large or too small, the differential circuit will appropriately scale it so that it falls within the voltage range that the MCU can recognize and process. It will also filter it to reduce noise and interference in the signal, thereby improving the quality and stability of the signal.

[0070] Specifically, the differential ratio of the signal processing circuit in this embodiment is:

[0071]

[0072] Let R 32 +R 33 +R 34 =R0, then the calculation formula of voltage U1 and voltage U2 is:

[0073]

[0074] Among them, U cp1 It represents the voltage collected by the microcontroller when the relay switch K1 is closed and the relay switch K2 is open. cp21 shows the voltage collected by the microcontroller when the relay switch K1 and the relay switch K2 are both closed, R0 represents the resistance value between the end of the protection resistor R35 in the third resistor unit close to the ground end and the ground end PE, and R0=R / 2.

[0075] Furthermore, the energy storage converter insulation resistance detection circuit of this embodiment further includes a clamping protection circuit, such as Figure 4 As shown, the clamping protection circuit includes a resistor R38, a capacitor C34, and a transient voltage suppressor TS30; the output end of the operational amplifier U6D is connected to one end of the resistor R38, the other end of the resistor R38 is connected to the input end of the microcontroller, the other end of the resistor R38 is also grounded via the capacitor C34, and the other end of the resistor R38 is also connected to the output port of the transient voltage suppressor TS30; the negative electrode of the transient voltage suppressor TS30 is connected to the positive electrode of the power supply, and the positive electrode is grounded. The clamping protection circuit has filtering and clamping protection functions to ensure that the voltage level of the signal does not exceed the maximum voltage that the MCU can withstand before it is output to the MCU pin. This protection mechanism can prevent damage to the MCU due to excessive voltage. The processed signal will be output to the MCU pin. Figure 4 In the circuit, the terminal Ucp is directly connected to the microcontroller MCU.

[0076] In this embodiment, the relay drive circuit receives a signal from the microcontroller MCU and uses a transistor to process the control signal. When the input signal sent by the MCU is at a high level, the transistor is turned on, the relay circuit is grounded, and the relay is energized; when the input signal is at a low level, the transistor is not turned on, the relay does not form a loop, and remains disconnected.

[0077] The relay is powered by an external 5V power supply. Figure 6As shown, in this embodiment, the relay drive circuit includes a resistor R186, a resistor R187, a resistor R186, a resistor R187, a transistor V1, and a transistor V2; one end of the resistor R186 is connected to the first control signal output terminal JDQ_K1-1 of the microcontroller, and the other end is connected to the base of the transistor V1; one end of the resistor R188 is connected to the base of the transistor V1, and the other end is grounded; the collector of the transistor V1 is connected to one end of the coil of the relay switch K1, and the emitter of the transistor V1 is grounded; the other end of the coil of the relay switch K1 is connected to the base of the transistor V1; The positive electrode of the source is connected, and the voltage-stabilizing diode VD2 is connected in parallel with the coil of the relay switch K1; one end of the resistor R187 is connected to the second control signal output terminal JDQ_K2-1 of the microcontroller, and the other end is connected to the base of the transistor V2; one end of the resistor R189 is connected to the base of the transistor V2, and the other end is grounded; the collector of the transistor V2 is connected to one end of the coil of the relay switch K2, and the emitter of the transistor V2 is grounded; the other end of the coil of the relay switch K2 is connected to the positive electrode of the power supply, and the voltage-stabilizing diode VD1 is connected in parallel with the coil of the relay switch K2.

[0078] In this embodiment, the microcontroller MCU receives the processed insulation resistance detection circuit signal through the ADC port, calculates the insulation resistance value according to the corresponding formula, and the program also includes a comparison logic to compare the calculated insulation resistance value with the preset safety threshold. If the measured value is lower than the safety range, the MCU will immediately trigger the alarm system and automatically cut off the power supply through the control relay to prevent possible electrical failures or safety accidents. The user interface allows the operator to monitor the insulation status and intervene manually when necessary. Through such a design, the insulation detection circuit of the energy storage inverter can effectively ensure the safe operation of the entire energy storage system.

[0079] Embodiment 3

[0080] like Figure 7 As shown, Embodiment 3 of the present invention provides an energy storage converter insulation resistance detection method, which is implemented based on an energy storage converter insulation resistance detection circuit described in Embodiment 1 or Embodiment 2, and includes the following steps:

[0081] Step 1: Initialize after power-on, and then detect the bus voltage;

[0082] Step 2: Control the relay switch K1 to be closed and the relay switch K2 to be open, and then collect the voltage U1; control the relay switch K1 and the relay switch K2 to be closed, and collect the voltage U2;

[0083] Step 3: Control the relay switch K1 and the relay switch K2 to be disconnected, and calculate the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2;

[0084] Step 4: Determine whether the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 are qualified. If qualified, end and wait for the next cycle to return to step 2 to continue controlling the relay for data collection. If unqualified, disconnect the main power relays and issue a fault alarm.

[0085] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. An energy storage converter insulation resistance detection circuit, characterized in that: include: A signal acquisition circuit, a signal processing circuit, a relay drive circuit and a microcontroller, wherein the signal acquisition circuit comprises a first resistance unit, a second resistance unit, a third resistance unit, a relay switch K1 and a relay switch K2; the first resistance unit, the second resistance unit and the third resistance unit have the same resistance value; one end of the first resistance unit is connected to the positive bus, and the other end is connected to one end of the second resistance unit; the other end of the second resistance unit is connected to the negative bus through the third resistance unit; one end of the relay switch K1 is connected to the other end of the second resistance unit, and the other end is grounded; one end of the relay switch K2 is connected to one end of the first resistance unit, and the other end is connected to the negative bus; the voltage at both ends of the third resistance unit is amplified by the signal processing circuit and then sent to the microcontroller; The relay drive circuit is used to control the on and off of the relay switch K1 and the relay switch K2; the microcontroller is used to calculate the magnitude of the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 according to the measured voltage across the third resistance unit.

2. The energy storage converter insulation resistance detection circuit according to claim 1, characterized in that: The calculation formula of positive electrode insulation resistance R1 and negative electrode insulation resistance R2 is: Wherein, U1 represents the voltage across the third resistor unit when the relay switch K1 is closed and the relay switch K2 is open, U2 represents the voltage across the third resistor unit when both the relay switch K1 and the relay switch K2 are closed, R represents the resistance values ​​of the first resistor unit, the second resistor unit, and the third resistor unit, and U B Indicates the DC bus voltage.

3. The energy storage converter insulation resistance detection circuit according to claim 2, characterized in that: The first resistance unit, the second resistance unit, and the third resistance unit each include a plurality of resistors connected in series.

4. The energy storage converter insulation resistance detection circuit according to claim 3, characterized in that: The first resistance unit includes resistors R20, R21, R22, R23, R24, and R25 connected in series in sequence, the second resistance unit includes resistors R26, R27, R28, R29, R30, and R31 connected in series in sequence, and the third resistance unit includes resistors R32, R33, R34, R36, R37, and R38 connected in series in sequence.

5. The energy storage converter insulation resistance detection circuit according to claim 3, characterized in that: The third resistance unit further includes a protection resistor R35, which is arranged in series in the branch where the third resistance unit is located and is located at the resistance center of the third resistance unit; the signal processing circuit includes an operational amplifier U6D, a resistor R192, a resistor R195, a capacitor C96, and a capacitor C98; The reverse input terminal of the operational amplifier U6D is connected to one end of the protection resistor R35 close to the ground terminal, the non-inverting input terminal is connected to one end of the protection resistor R35 close to the negative bus, the output terminal of the operational amplifier U6D is connected to the reverse input terminal through the resistor R192, and the capacitor C96 is connected in parallel with the resistor R192; one end of the resistor R195 is connected to the non-inverting input terminal of the operational amplifier U6D, and the other end is grounded, the capacitor C98 is connected in parallel with the resistor R195, and the output terminal of the operational amplifier U6D is connected to the input terminal of the microcontroller.

6. The energy storage converter insulation resistance detection circuit according to claim 5, characterized in that: The signal processing circuit also includes a transient voltage suppressor TS25 and a transient voltage suppressor TS26, wherein the output port of the transient voltage suppressor TS25 is connected to the inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply; The output port of the transient voltage suppressor TS26 is connected to the non-inverting input terminal of the operational amplifier U6D, the positive electrode is connected to the negative electrode of the power supply, and the negative electrode is connected to the positive electrode of the power supply.

7. The energy storage converter insulation resistance detection circuit according to claim 5, characterized in that: It also includes a clamping protection circuit, which includes a resistor R38, a capacitor C34, and a transient voltage suppressor TS30; the output end of the operational amplifier U6D is connected to one end of the resistor R38, the other end of the resistor R38 is connected to the input end of the microcontroller, the other end of the resistor R38 is also grounded via the capacitor C34, and the other end of the resistor R38 is also connected to the output port of the transient voltage suppressor TS30; the negative electrode of the transient voltage suppressor TS30 is connected to the positive electrode of the power supply, and the positive electrode is grounded.

8. The energy storage converter insulation resistance detection circuit according to claim 5, characterized in that: The calculation formulas for voltage U1 and voltage U2 are: Among them, U cp1 It represents the voltage collected by the microcontroller when the relay switch K1 is closed and the relay switch K2 is open. cp2 1 shows the voltage collected by the microcontroller when the relay switch K1 and the relay switch K2 are both closed, and R0 represents the resistance value between the end of the protection resistor R35 in the third resistor unit close to the ground end and the ground end.

9. The energy storage converter insulation resistance detection circuit according to claim 1, characterized in that: The relay drive circuit includes a resistor R186, a resistor R187, a resistor R186, a resistor R187, a transistor V1, and a transistor V2; one end of the resistor R186 is connected to the first control signal output end of the microcontroller, and the other end is connected to the base of the transistor V1; one end of the resistor R188 is connected to the base of the transistor V1, and the other end is grounded; the collector of the transistor V1 is connected to one end of the coil of the relay switch K1, and the emitter of the transistor V1 is grounded; the other end of the coil of the relay switch K1 is connected to the positive electrode of the power supply, and the voltage regulator diode VD2 is connected in parallel with the coil of the relay switch K1; One end of the resistor R187 is connected to the second control signal output end of the microcontroller, and the other end is connected to the base of the transistor V2; one end of the resistor R189 is connected to the base of the transistor V2, and the other end is grounded; the collector of the transistor V2 is connected to one end of the coil of the relay switch K2, and the emitter of the transistor V2 is grounded; the other end of the coil of the relay switch K2 is connected to the positive electrode of the power supply, and the voltage regulator diode VD1 is connected in parallel with the coil of the relay switch K2.

10. A method for detecting insulation resistance of an energy storage converter, implemented based on an insulation resistance detection circuit of an energy storage converter according to claims 1 to 9, characterized in that: The following steps are involved: Step 1: Initialize after power-on, and then detect the bus voltage; Step 2: Control the relay switch K1 to be closed and the relay switch K2 to be open, and then collect the voltage U1; control the relay switch K1 and the relay switch K2 to be closed, and collect the voltage U2; Step 3: Control the relay switch K1 and the relay switch K2 to be disconnected, and calculate the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2; Step 4: Determine whether the positive electrode insulation resistance R1 and the negative electrode insulation resistance R2 are qualified. If qualified, end and wait for the next cycle to return to step 2 to continue controlling the relay for data collection. If unqualified, disconnect the main power relays and issue a fault alarm.

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