Insulation impedance detection method and detection device

Abstract

The application is suitable for the technical field of insulation impedance detection, and provides an insulation impedance detection method and a detection device. The method comprises the following steps: controlling a first unbalanced bridge switch to be closed, obtaining a current negative DC bus voltage, and obtaining a first negative DC bus voltage; if the first negative DC bus voltage is less than a first preset value, controlling the first unbalanced bridge switch and a first matching switch to be closed, obtaining a current negative DC bus voltage, and obtaining a second negative DC bus voltage; controlling a second unbalanced bridge switch to be closed, obtaining a current negative DC bus voltage, and obtaining a third negative DC bus voltage; and determining a positive DC bus insulation impedance and a negative DC bus insulation impedance according to the second negative DC bus voltage and the third negative DC bus voltage. When the DC bus voltage is low, the first matching resistance is connected to increase the detection voltage value, so that the detection precision of the insulation impedance is effectively improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of insulation impedance detection, and particularly relates to an insulation impedance detection method and a detection device. BACKGROUND

[0002] A photovoltaic power generation system converts light energy into electric energy and has been rapidly developed as a clean energy. In the photovoltaic power generation system, a solar cell panel is connected to an input of a photovoltaic inverter through a positive direct-current bus and a negative direct-current bus. Insulation impedance includes positive insulation impedance of the positive direct-current bus to ground and negative insulation impedance of the negative direct-current bus to ground. When the insulation impedance of the photovoltaic inverter is too low, the entire photovoltaic power generation system will be damaged. Therefore, protection of the insulation impedance of the photovoltaic inverter to ground is very important.

[0003] In the prior art, a bridge method (accessing an unbalanced bridge and a balanced bridge) is usually used to sample positive and negative bus voltages to detect insulation impedance. Due to limited sampling accuracy, when the voltage of a direct-current power supply is relatively small, the positive and negative bus voltages obtained by sampling are inaccurate, which seriously affects the calculation accuracy of the insulation impedance. SUMMARY

[0004] Therefore, the embodiments of the application provide an insulation impedance detection method and a detection device to solve the problem of low insulation impedance accuracy in the prior art due to limited sampling accuracy when the voltage of a direct-current power supply is relatively small.

[0005] A first aspect of the embodiments of the application provides an insulation impedance detection method applied to an insulation impedance detection circuit. The insulation impedance detection circuit includes a first balanced bridge resistor, a second balanced bridge resistor, a first unbalanced bridge resistor, a second unbalanced bridge resistor, a first unbalanced bridge switch, a second unbalanced bridge switch, a first matching resistor, and a first matching switch. The first balanced bridge resistor is connected between a positive direct-current bus and a ground wire, and the second balanced bridge resistor is connected between a negative direct-current bus and the ground wire. The first unbalanced bridge resistor and the first unbalanced bridge switch are connected in series between the positive direct-current bus and the ground wire, and the second unbalanced bridge resistor and the second unbalanced bridge switch are connected in series between the negative direct-current bus and the ground wire. The first matching resistor and the first matching switch are connected in series between the positive direct-current bus and the ground wire. The method includes the following steps.

[0006] The first unbalanced bridge switch is closed, the second unbalanced bridge switch is opened, and the first matching switch is opened, a current negative direct-current bus voltage is obtained, and a first negative direct-current bus voltage is obtained.

[0007] If the first negative DC bus voltage is less than the first preset value, the first unbalanced bridge switch is controlled to be closed, the second unbalanced bridge switch is controlled to be opened, and the first matching switch is controlled to be closed, and the current negative DC bus voltage is obtained to obtain a second negative DC bus voltage; the first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed, and the first matching switch is controlled to be opened, and the current negative DC bus voltage is obtained to obtain a third negative DC bus voltage.

[0008] The positive DC bus insulation impedance and the negative DC bus insulation impedance are determined according to the second negative DC bus voltage and the third negative DC bus voltage.

[0009] The second aspect of the embodiment of the application provides an insulation impedance detection method, which is applied to an insulation impedance detection circuit; the insulation impedance detection circuit comprises a first balanced bridge resistor, a second balanced bridge resistor, a first unbalanced bridge resistor, a second unbalanced bridge resistor, a first unbalanced bridge switch, a second unbalanced bridge switch, a third matching resistor and a third matching switch; the first balanced bridge resistor is connected between a positive DC bus and a ground wire, and the second balanced bridge resistor is connected between a negative DC bus and the ground wire; the first unbalanced bridge resistor and the first unbalanced bridge switch are connected in series between the positive DC bus and the ground wire, the second unbalanced bridge resistor and the second unbalanced bridge switch are connected in series between the negative DC bus and the ground wire, and the third matching resistor and the third matching switch are connected in series between the negative DC bus and the ground wire; the method comprises the following steps:

[0010] The first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed, and the first matching switch is controlled to be opened, and the current positive DC bus voltage is obtained to obtain a first positive DC bus voltage.

[0011] If the first positive DC bus voltage is less than the first preset value, the first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed, and the third matching switch is controlled to be closed, and the current positive DC bus voltage is obtained to obtain a second positive DC bus voltage; the first unbalanced bridge switch is controlled to be closed, the second unbalanced bridge switch is controlled to be opened, and the third matching switch is controlled to be opened, and the current positive DC bus voltage is obtained to obtain a third positive DC bus voltage.

[0012] The positive DC bus insulation impedance and the negative DC bus insulation impedance are determined according to the second positive DC bus voltage and the third positive DC bus voltage.

[0013] The third aspect of the embodiment of the application provides a detection device, which comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor; when the processor executes the computer program, the steps of the insulation impedance detection method provided in the first aspect of the embodiment of the application or the insulation impedance detection method provided in the second aspect of the embodiment of the application are implemented.

[0014] The fourth aspect of the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the insulation impedance detection method provided by the first aspect of the embodiment of the present application or the insulation impedance detection method provided by the second aspect of the embodiment of the present application.

[0015] The embodiment of the present application provides an insulation impedance detection method and a detection device, and the insulation impedance detection method is applied to an insulation impedance detection circuit. The first balanced bridge resistor is connected between the positive DC bus and the ground wire, and the second balanced bridge resistor is connected between the negative DC bus and the ground wire. The first unbalanced bridge resistor and the first unbalanced bridge switch are connected in series between the positive DC bus and the ground wire, and the second unbalanced bridge resistor and the second unbalanced bridge switch are connected in series between the negative DC bus and the ground wire. The first matching resistor and the first matching switch are connected in series between the positive DC bus and the ground wire. The embodiment of the present application samples the voltage of the positive DC bus or the voltage of the negative DC bus to determine the insulation impedance, and when the detected voltage is too low, the matching resistor is connected to increase the voltage of the positive DC bus or the negative DC bus, so that the sampling accuracy is not low when the voltage is too low, and the detection accuracy of the insulation impedance is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0017] Figure 1 It is a circuit schematic diagram of an insulation impedance detection circuit provided by the embodiment of the present application.

[0018] Figure 2 is an implementation flow diagram of an insulation impedance detection method provided by an embodiment of the present application;

[0019] Figure 3 is a circuit principle diagram of another insulation impedance detection circuit provided by an embodiment of the present application;

[0020] Figure 4 is a circuit principle diagram of another insulation impedance detection circuit provided by an embodiment of the present application;

[0021] Figure 5 is an implementation flow diagram of another insulation impedance detection method provided by an embodiment of the present application;

[0022] Figure 6 is a schematic diagram of an insulation impedance detection device provided by an embodiment of the present application;

[0023] Figure 7 is a schematic diagram of another insulation impedance detection device provided by an embodiment of the present application;

[0024] Figure 8 is a schematic diagram of a detection device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following description, for the purpose of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0026] In order to illustrate the technical solutions of the present application, the following will be described through specific embodiments.

[0027] Reference Figure 1 and Figure 2 The embodiments of the present application provide an insulation impedance detection method, applied to Figure 1The insulation impedance detection circuit shown; the insulation impedance detection circuit comprises: a first balanced bridge resistor R01, a second balanced bridge resistor R02, a first unbalanced bridge resistor R1, a second unbalanced bridge resistor R2, a first unbalanced bridge switch k1, a second unbalanced bridge switch k2, a first matching resistor Rp1 and a first matching switch Kp1; the first balanced bridge resistor R01 is connected between the positive DC bus BUS+ and the ground wire, and the second balanced bridge resistor R02 is connected between the negative DC bus BUS- and the ground wire; the first unbalanced bridge resistor R1 and the first unbalanced bridge switch k1 are connected in series between the positive DC bus BUS+ and the ground wire, and the second unbalanced bridge resistor R2 and the second unbalanced bridge switch k2 are connected in series between the negative DC bus BUS- and the ground wire; the first matching resistor Rp1 and the first matching switch Kp1 are connected in series between the positive DC bus BUS+ and the ground wire; the method comprises:

[0028] S101: control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be disconnected and the first matching switch Kp1 to be disconnected, obtain the current negative DC bus voltage, and obtain the first negative DC bus voltage;

[0029] S102: if the first negative DC bus voltage is less than the first preset value, control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be disconnected and the first matching switch Kp1 to be closed, and obtain the current negative DC bus voltage to obtain the second negative DC bus voltage; control the first unbalanced bridge switch k1 to be disconnected, the second unbalanced bridge switch k2 to be closed and the first matching switch Kp1 to be disconnected, and obtain the current negative DC bus voltage to obtain the third negative DC bus voltage;

[0030] S103: according to the second negative DC bus voltage and the third negative DC bus voltage, determine the positive DC bus insulation impedance and the negative DC bus insulation impedance.

[0031] In the prior art, the bridge method is usually used to detect the insulation impedance of the positive and negative buses, the first unbalanced bridge resistor R1 and the second unbalanced bridge resistor R2 are connected, the positive and negative DC bus voltages are sampled, a binary quadratic mode is obtained, and then the positive DC bus insulation impedance and the negative DC bus insulation impedance are calculated. Due to the influence of sampling accuracy, the smaller the voltage is, the greater the sampling error is. Therefore, when the DC bus voltage is low, the sampling accuracy is affected, the error of the sampled positive DC bus voltage or negative DC bus voltage is large, and the accuracy of the insulation impedance is greatly reduced.

[0032] In the embodiment of the present application, the first balance bridge resistor R01 and the second balance bridge resistor R02 form a balance bridge (the first balance bridge resistor R01 and the second balance bridge resistor R02 have the same resistance value), and the first unbalance bridge resistor R1 and the second unbalance bridge resistor R2 form an unbalance bridge (the first unbalance bridge resistor R1 and the second unbalance bridge resistor R2 have different resistance values). The negative DC bus voltage is sampled after the first unbalance bridge resistor R1 is connected, and it is determined whether the first negative DC bus voltage obtained by sampling is too low. If the first negative DC bus voltage is too low, it indicates that the voltage difference between the positive bus and the negative bus is small, and then the first matching resistor Rp1 is connected to reduce the equivalent resistance of the positive DC bus BUS+ to the ground. This can not only increase the value of the second negative DC bus voltage obtained by sampling in the case that the voltage difference between the positive bus and the negative bus is low, but also increase the difference between the second negative DC bus voltage obtained by sampling when the first unbalance bridge resistor R1 is switched and the third negative DC bus voltage obtained by sampling when the second unbalance bridge resistor R2 is switched, thereby reducing the sampling error and the calculation error and improving the detection accuracy of the insulation impedance.

[0033] In some embodiments, S103 can include:

[0034] S1031: obtaining the voltage difference between the positive bus and the negative bus;

[0035] S1032: subtracting the voltage difference between the positive bus and the negative bus from the second negative DC bus voltage to obtain the second positive DC bus voltage;

[0036] S1033: subtracting the voltage difference between the positive bus and the negative bus from the third negative DC bus voltage to obtain the third positive DC bus voltage;

[0037] S1034: determining the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second positive DC bus voltage, the second negative DC bus voltage, the third positive DC bus voltage and the third negative DC bus voltage.

[0038] The embodiment of the present application can sample the voltage difference between the positive bus and the negative bus, and then obtain the corresponding second positive DC bus voltage and second negative DC bus voltage according to the voltage difference between the positive bus and the negative bus, and then obtain the binary quadratic equation.

[0039] In some embodiments, the calculation formula of the positive DC bus insulation impedance and the negative DC bus insulation impedance can be:

[0040]

[0041]

[0042] wherein, U 2+ is the second positive DC bus voltage, U 2- is the second negative DC bus voltage, U 3+ is the third positive DC bus voltage, and U3- R0 is the value of the first balance bridge resistance R01, R1 is the value of the first unbalance bridge resistance R1, R2 is the value of the second unbalance bridge resistance R2, R x1 R0 is the value of the first balance bridge resistance R01, R1 is the value of the first unbalance bridge resistance R1, R2 is the value of the second unbalance bridge resistance R2, R x2 R0 is the value of the first balance bridge resistance R01, R1 is the value of the first unbalance bridge resistance R1, R2 is the value of the second unbalance bridge resistance R2, R p1 R0 is the value of the first balance bridge resistance R01, R1 is the value of the first unbalance bridge resistance R1, R2 is the value of the second unbalance bridge resistance R2, R

[0043] Reference Figure 1 When the second negative DC bus voltage is sampled, the first unbalance bridge switch k1 is closed, the second unbalance bridge switch k2 is opened, and the first matching switch Kp1 is closed, the equivalent resistance of the positive DC bus BUS+ to the ground is the parallel connection of the positive DC bus insulation resistance and the first balance bridge resistance R01, the first unbalance bridge resistance R1 and the first matching resistance Rp1; the equivalent resistance of the negative DC bus BUS- to the ground is the parallel connection of the negative DC bus insulation resistance Rx2 and the second balance bridge resistance R02. When the third negative DC bus voltage is sampled, the first unbalance bridge switch k1 is opened, the second unbalance bridge switch k2 is closed, and the first matching switch Kp1 is opened, the equivalent resistance of the positive DC bus BUS+ to the ground is the parallel connection of the positive DC bus insulation resistance Rx1 and the first balance bridge resistance R01, and the equivalent resistance of the negative DC bus BUS- to the ground is the parallel connection of the negative DC bus insulation resistance Rx2, the second balance bridge resistance R02 and the second unbalance bridge resistance R2.

[0044] Thus, the above formula is obtained according to Ohm's law. Given the resistance values of each resistance, R x1 and R x2 are unknown quantities, and the rest of the parameters are known quantities. The values of R x1 and R x2 can be obtained by solving the above binary quadratic.

[0045] In some embodiments, the above method can further include:

[0046] S104: If the first negative DC bus voltage is not less than the first preset value, the first unbalance bridge switch k1 is opened, the second unbalance bridge switch k2 is closed, and the first matching switch Kp1 is opened, and the current negative DC bus voltage is obtained to obtain the fourth negative DC bus voltage.

[0047] S105: The positive DC bus insulation resistance and the negative DC bus insulation resistance are determined according to the first negative DC bus voltage and the fourth negative DC bus voltage.

[0048] In the embodiments of the present application, if the first negative DC bus voltage is not less than the first preset value, it indicates that the sampled voltage value is large enough and will not be affected by the sampling accuracy, so the first matching switch Kp1 does not need to be connected, and thus the insulation resistance can be determined according to the method of the prior art.

[0049] As described above, the voltage difference between the positive bus and the negative bus can be obtained, the voltage difference between the positive bus and the negative bus is subtracted by the first negative DC bus voltage to obtain the first positive DC bus voltage; the voltage difference between the positive bus and the negative bus is subtracted by the fourth negative DC bus voltage to obtain the fourth positive DC bus voltage, and then the positive DC bus insulation impedance and the negative DC bus insulation impedance are calculated according to the first negative DC bus voltage, the first positive DC bus voltage, the fourth negative DC bus voltage and the fourth positive DC bus voltage.

[0050] Based on the above, the calculation formula of the positive DC bus insulation impedance and the negative DC bus insulation impedance can be:

[0051]

[0052]

[0053] Wherein, U 1+ is the first positive DC bus voltage, U 1- is the first negative DC bus voltage, U 4+ is the fourth positive DC bus voltage, U 4- is the fourth negative DC bus voltage.

[0054] Similarly, based on Ohm's law, a binary quadratic equation is established to calculate the positive DC bus insulation impedance and the negative DC bus insulation impedance.

[0055] In some embodiments, referring to Figure 3 , the insulation impedance detection circuit can further include: a second matching resistor Rp2 and a second matching switch Kp2; the second matching resistor Rp2 and the second matching switch Kp2 are connected in series between the positive DC bus BUS+ and the ground line; S102 can include:

[0056] S1021: if the first negative DC bus voltage is less than the first preset value, the first unbalanced bridge switch k1 is closed, the second unbalanced bridge switch k2 is opened, the first matching switch Kp1 is closed and the second matching switch Kp2 is opened, and the current negative DC bus voltage is obtained to obtain the fifth negative DC bus voltage;

[0057] S1022: determine the difference between the fifth negative DC bus voltage and the first negative DC bus voltage;

[0058] S1023: if the difference is less than the second preset value, the first unbalanced bridge switch k1 is closed, the second unbalanced bridge switch k2 is opened, the first matching switch Kp1 is closed and the second matching switch Kp2 is closed, and the current negative DC bus voltage is obtained to obtain the second negative DC bus voltage;

[0059] S1024: If the difference is not less than the second preset value, the fifth negative DC bus voltage is taken as the second negative DC bus voltage.

[0060] S1025: The first unbalanced bridge switch k1 is controlled to be opened, the second unbalanced bridge switch k2 is controlled to be closed, the first matching switch Kp1 is controlled to be opened, and the second matching switch Kp2 is controlled to be opened, and the current negative DC bus voltage is obtained, to obtain the third negative DC bus voltage.

[0061] In the embodiment of the application, since the voltage difference between the positive bus and the negative bus is uncertain, the voltage variation before and after the first matching resistor Rp1 is incorporated may not be large enough, and the actual application requirements cannot still be met. Therefore, in the embodiment of the application, if the voltage variation before and after the first matching resistor Rp1 is incorporated is not enough, it indicates that the voltage difference between the positive bus and the negative bus is still small, and the second matching resistor Rp2 is controlled to be incorporated, to further reduce the equivalent resistance of the positive DC bus BUS+ to the ground, and improve the value of the second negative DC bus voltage obtained by the current sampling. Meanwhile, the difference between the second negative DC bus voltage and the third negative DC bus voltage can also be increased, so as to reduce the sampling error and the calculation error, improve the accuracy of the insulation impedance detection, and prevent the accuracy of the insulation impedance from being affected by the low sampling precision.

[0062] Further, the insulation impedance detection circuit can further include at least one fourth matching resistor; one or more matching resistors can be selected to be incorporated according to actual application requirements, so that the voltage variation meets the actual application requirements.

[0063] In some embodiments, the value R of the first matching resistor Rp1 is p1 The calculation formula can be:

[0064]

[0065] Wherein, R0 is the value of the first balanced bridge resistor R01.

[0066] In the embodiment of the application, the value of the first matching resistor Rp1 is set to be one-tenth of the value of the first balanced bridge resistor R01, so that when the first matching resistor Rp1 is incorporated, the variation of the value of the negative DC bus voltage is appropriate, and no additional error is caused, and the accuracy of the insulation impedance calculation is not affected.

[0067] In some embodiments, the first preset value can be 30V.

[0068] In some embodiments, the second preset value can be 30V.

[0069] With reference to Figure 4 and Figure 5 , the embodiment of the application further provides an insulation impedance detection method, which is applied to Figure 4The insulation impedance detection circuit shown; the insulation impedance detection circuit comprises: a first balanced bridge resistor R01, a second balanced bridge resistor R02, a first unbalanced bridge resistor R1, a second unbalanced bridge resistor R2, a first unbalanced bridge switch k1, a second unbalanced bridge switch k2, a third matching resistor Rp3 and a third matching switch Kp3; the first balanced bridge resistor R01 is connected between the positive DC bus BUS+ and the ground wire, and the second balanced bridge resistor R02 is connected between the negative DC bus BUS- and the ground wire; the first unbalanced bridge resistor R1 and the first unbalanced bridge switch k1 are connected in series between the positive DC bus BUS+ and the ground wire, and the second unbalanced bridge resistor R2 and the second unbalanced bridge switch k2 are connected in series between the negative DC bus BUS- and the ground wire; the third matching resistor Rp3 and the third matching switch Kp3 are connected in series between the negative DC bus BUS- and the ground wire; the method comprises:

[0070] S201: control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, and the first matching switch Kp1 to be opened, obtain the current positive DC bus voltage, and obtain the first positive DC bus voltage;

[0071] S202: if the first positive DC bus voltage is less than the first preset value, control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, and the third matching switch Kp3 to be closed, and obtain the current positive DC bus voltage to obtain the second positive DC bus voltage; control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, and the third matching switch Kp3 to be opened, and obtain the current positive DC bus voltage to obtain the third positive DC bus voltage;

[0072] S203: according to the second positive DC bus voltage and the third positive DC bus voltage, the positive DC bus insulation impedance and the negative DC bus insulation impedance are determined.

[0073] As above, the embodiment of the present application can also sample the positive DC bus voltage, and determine the insulation impedance according to the positive DC bus voltage. Correspondingly, the third matching resistor Rp3 and the third matching switch Kp3 can be arranged between the negative DC bus BUS- and the ground wire to adjust the value of the sampling voltage, so as to ensure the accuracy of the insulation impedance calculation.

[0074] The specific calculation method is the same as above, and will not be repeated here.

[0075] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0076] Corresponding to the above embodiment, with reference to Figure 6 , the embodiment of the present application provides an insulation impedance detection device, which is applied toFigure 1 The insulation impedance detection circuit shown; the insulation impedance detection circuit comprises: a first balanced bridge resistor R01, a second balanced bridge resistor R02, a first unbalanced bridge resistor R1, a second unbalanced bridge resistor R2, a first unbalanced bridge switch k1, a second unbalanced bridge switch k2, a first matching resistor Rp1 and a first matching switch Kp1; the first balanced bridge resistor R01 is connected between the positive DC bus BUS+ and the ground wire, and the second balanced bridge resistor R02 is connected between the negative DC bus BUS- and the ground wire; the first unbalanced bridge resistor R1 and the first unbalanced bridge switch k1 are connected in series between the positive DC bus BUS+ and the ground wire, and the second unbalanced bridge resistor R2 and the second unbalanced bridge switch k2 are connected in series between the negative DC bus BUS- and the ground wire; the first matching resistor Rp1 and the first matching switch Kp1 are connected in series between the positive DC bus BUS+ and the ground wire; the device comprises:

[0077] The first switch control module 21 is used for controlling the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened and the first matching switch Kp1 to be opened, obtaining the current negative DC bus voltage, and obtaining the first negative DC bus voltage;

[0078] The first judgment module 22 is used for controlling the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened and the first matching switch Kp1 to be closed if the first negative DC bus voltage is less than the first preset value, obtaining the current negative DC bus voltage, and obtaining the second negative DC bus voltage; controlling the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed and the first matching switch Kp1 to be opened, obtaining the current negative DC bus voltage, and obtaining the third negative DC bus voltage;

[0079] The first result output module 23 is used for determining the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second negative DC bus voltage and the third negative DC bus voltage.

[0080] In some embodiments, the device can further comprise:

[0081] The second judgment module 24 is used for controlling the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed and the first matching switch Kp1 to be opened if the first negative DC bus voltage is not less than the first preset value, obtaining the current negative DC bus voltage, and obtaining the fourth negative DC bus voltage;

[0082] The second result output module 25 is used for determining the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the first negative DC bus voltage and the fourth negative DC bus voltage.

[0083] In some embodiments, reference Figure 3The insulation impedance detection circuit can further include a second matching resistor Rp2 and a second matching switch Kp2; the second matching resistor Rp2 and the second matching switch Kp2 are connected in series between the positive DC bus BUS+ and the ground line; the first judging module 22 can include:

[0084] The first judging unit 221 is configured to, if the first negative DC bus voltage is less than a first preset value, control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, the first matching switch Kp1 to be closed, and the second matching switch Kp2 to be opened, and obtain a current negative DC bus voltage to obtain a fifth negative DC bus voltage.

[0085] The difference determining unit 222 is configured to determine a difference between the fifth negative DC bus voltage and the first negative DC bus voltage.

[0086] The second judging unit 223 is configured to, if the difference is less than a second preset value, control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, the first matching switch Kp1 to be closed, and the second matching switch Kp2 to be closed, and obtain a current negative DC bus voltage to obtain a second negative DC bus voltage.

[0087] The third judging unit 224 is configured to, if the difference is not less than the second preset value, take the fifth negative DC bus voltage as the second negative DC bus voltage.

[0088] The switch control unit 225 is configured to control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, the first matching switch Kp1 to be opened, and the second matching switch Kp2 to be opened, and obtain a current negative DC bus voltage to obtain a third negative DC bus voltage.

[0089] In some embodiments, the first result output module 23 can include:

[0090] The voltage obtaining unit 231 is configured to obtain a voltage difference between the positive bus and the negative bus.

[0091] The first difference calculating unit 232 is configured to subtract the second negative DC bus voltage from the voltage difference between the positive bus and the negative bus to obtain a second positive DC bus voltage.

[0092] The second difference calculating unit 233 is configured to subtract the third negative DC bus voltage from the voltage difference between the positive bus and the negative bus to obtain a third positive DC bus voltage.

[0093] The insulation impedance calculating unit 234 is configured to determine the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second positive DC bus voltage, the second negative DC bus voltage, the third positive DC bus voltage, and the third negative DC bus voltage.

[0094] In some embodiments, the calculation formula of the positive DC bus insulation impedance and the negative DC bus insulation impedance can be:

[0095]

[0096]

[0097] wherein U 2+ is the second positive DC bus voltage, U 2- is the second negative DC bus voltage, U 3+ is the third positive DC bus voltage, U 3- is the third negative DC bus voltage, R x1 is the positive DC bus insulation impedance, R x2 is the negative DC bus insulation impedance, R0 is the value of the first balanced bridge resistor R01, R1 is the value of the first unbalanced bridge resistor R1, R2 is the value of the second unbalanced bridge resistor R2, and R p1 is the value of the first matching resistor Rp1.

[0098] In some embodiments, the calculation formula of the value R p1 of the first matching resistor Rp1 can be:

[0099]

[0100] wherein R0 is the value of the first balanced bridge resistor R01.

[0101] In some embodiments, the first preset value can be 30V.

[0102] In some embodiments, the second preset value can be 30V.

[0103] With reference to Figure 7 , the embodiments of the present application also provide an insulation impedance detection device, which is applied to Figure 4 the insulation impedance detection circuit shown in the figure; the insulation impedance detection circuit comprises a first balanced bridge resistor R01, a second balanced bridge resistor R02, a first unbalanced bridge resistor R1, a second unbalanced bridge resistor R2, a first unbalanced bridge switch k1, a second unbalanced bridge switch k2, a third matching resistor Rp3, and a third matching switch Kp3; the first balanced bridge resistor R01 is connected between the positive DC bus BUS+ and the ground wire, and the second balanced bridge resistor R02 is connected between the negative DC bus BUS- and the ground wire; the first unbalanced bridge resistor R1 and the first unbalanced bridge switch k1 are connected in series between the positive DC bus BUS+ and the ground wire, and the second unbalanced bridge resistor R2 and the second unbalanced bridge switch k2 are connected in series between the negative DC bus BUS- and the ground wire; the third matching resistor Rp3 and the third matching switch Kp3 are connected in series between the negative DC bus BUS- and the ground wire; the device can comprise:

[0104] The second switch control module 31 is used to control the first unbalanced bridge switch k1 to open, the second unbalanced bridge switch k2 to close, and the first matching switch Kp1 to open, so as to obtain the current positive DC bus voltage and obtain the first positive DC bus voltage.

[0105] The third judgment module 32 is used to control the first unbalanced bridge switch k1 to open, the second unbalanced bridge switch k2 to close, and the third matching switch Kp3 to close if the first positive DC bus voltage is less than the first preset value, and to obtain the current positive DC bus voltage to obtain the second positive DC bus voltage; and to control the first unbalanced bridge switch k1 to close, the second unbalanced bridge switch k2 to open, and the third matching switch Kp3 to open, and to obtain the current positive DC bus voltage to obtain the third positive DC bus voltage.

[0106] The third result output module 33 is used to determine the positive DC bus insulation impedance and the negative DC bus insulation impedance based on the second positive DC bus voltage and the third positive DC bus voltage.

[0107] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the detection equipment can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above device can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0108] Figure 8 This is a schematic block diagram of a detection device provided in an embodiment of the present invention. Figure 8 As shown, the detection device 4 in this embodiment includes: one or more processors 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40. When the processor 40 executes the computer program 42, it implements the steps in the various insulation resistance detection method embodiments described above, for example... Figure 2 Steps S101 to S103 shown, or Figure 5 Steps S201 to S203 are shown in the diagram. Alternatively, when processor 40 executes computer program 42, it implements the functions of each module / unit in the above-described insulation resistance detection device embodiment, for example... Figure 6the functions of the illustrated modules 21 to 23 or as Figure 7 the functions of the illustrated modules 31 to 33.

[0109] Exemplarily, the computer program 42 can be divided into one or more modules / units, one or more of which are stored in the memory 41 and executed by the processor 40 to complete the present application. One or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 42 in the detection device 4. For example, the computer program 42 can be divided into a first switch control module 21, a first judgment module 22, and a first result output module 23.

[0110] The first switch control module 21 is configured to control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, and the first matching switch Kp1 to be opened, obtain a current negative DC bus voltage, and obtain a first negative DC bus voltage.

[0111] The first judgment module 22 is configured to, if the first negative DC bus voltage is less than a first preset value, control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, and the first matching switch Kp1 to be closed, and obtain a current negative DC bus voltage to obtain a second negative DC bus voltage; control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, and the first matching switch Kp1 to be opened, and obtain a current negative DC bus voltage to obtain a third negative DC bus voltage.

[0112] The first result output module 23 is configured to determine the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second negative DC bus voltage and the third negative DC bus voltage.

[0113] For another example, the computer program 42 can be divided into a second switch control module 31, a third judgment module 32, and a third result output module 33.

[0114] The second switch control module 31 is configured to control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, and the first matching switch Kp1 to be opened, obtain a current positive DC bus voltage, and obtain a first positive DC bus voltage.

[0115] The third judgment module 32 is configured to, if the first positive DC bus voltage is less than a first preset value, control the first unbalanced bridge switch k1 to be opened, the second unbalanced bridge switch k2 to be closed, and the third matching switch Kp3 to be closed, and obtain a current positive DC bus voltage to obtain a second positive DC bus voltage; control the first unbalanced bridge switch k1 to be closed, the second unbalanced bridge switch k2 to be opened, and the third matching switch Kp3 to be opened, and obtain a current positive DC bus voltage to obtain a third positive DC bus voltage.

[0116] The third result output module 33 is configured to determine the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second positive DC bus voltage and the third positive DC bus voltage.

[0117] The other modules or units are not described here.

[0118] The detection device 4 includes but is not limited to a processor 40 and a memory 41. Those skilled in the art can understand that the detection device 4 can include more or fewer components than those shown, or combine some components, or include different components, for example, the detection device 4 can also include an input device, an output device, a network access device, a bus, etc. Figure 8 The detection device 4 is only an example and does not constitute a limitation on the detection device 4, and can include more or fewer components than those shown, or combine some components, or include different components, for example, the detection device 4 can also include an input device, an output device, a network access device, a bus, etc.

[0119] The processor 40 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0120] The memory 41 can be an internal storage unit of the detection device, such as a hard disk or a memory of the detection device. The memory 41 can also be an external storage device of the detection device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. Further, the memory 41 can include both the internal storage unit and the external storage device of the detection device. The memory 41 is used to store the computer program 42 and other programs and data required by the detection device. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0121] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in detail in a certain embodiment can refer to the related description of other embodiments.

[0122] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0123] In the embodiments provided in the present application, it should be understood that the disclosed detection device and method can be implemented in other ways. For example, the detection device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0124] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. can be located in one place or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0125] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0126] The integrated modules / units, if implemented in the form of software functional units and sold or used as independent products, can be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiments can also be implemented by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various method embodiments can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), electric carrier wave signal, telecommunication signal and software distribution medium, etc.

[0127] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An insulation impedance detection method characterized by, The application is applied to an insulation impedance detection circuit; the insulation impedance detection circuit comprises: a first balanced bridge resistor, a second balanced bridge resistor, a first unbalanced bridge resistor, a second unbalanced bridge resistor, a first unbalanced bridge switch, a second unbalanced bridge switch, a first matching resistor and a first matching switch; the first balanced bridge resistor is connected between a positive DC bus and a ground wire, and the second balanced bridge resistor is connected between a negative DC bus and the ground wire; the first unbalanced bridge resistor and the first unbalanced bridge switch are connected in series between the positive DC bus and the ground wire, and the second unbalanced bridge resistor and the second unbalanced bridge switch are connected in series between the negative DC bus and the ground wire; the first matching resistor and the first matching switch are connected in series between the positive DC bus and the ground wire; the method comprises: controlling the first unbalanced bridge switch to be closed, the second unbalanced bridge switch to be opened and the first matching switch to be opened, obtaining a current negative DC bus voltage to obtain a first negative DC bus voltage; if the first negative DC bus voltage is less than a first preset value, controlling the first unbalanced bridge switch to be closed, the second unbalanced bridge switch to be opened and the first matching switch to be closed, and obtaining a current negative DC bus voltage to obtain a second negative DC bus voltage; controlling the first unbalanced bridge switch to be opened, the second unbalanced bridge switch to be closed and the first matching switch to be opened, and obtaining a current negative DC bus voltage to obtain a third negative DC bus voltage; determining the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the second negative DC bus voltage and the third negative DC bus voltage; The value R of the first matching resistance p1 The calculation formula is: wherein R0 is the value of the first balanced bridge resistor.

2. The insulation impedance detection method of claim 1, wherein, The method further comprises: if the first negative DC bus voltage is not less than the first preset value, controlling the first unbalanced bridge switch to be opened, the second unbalanced bridge switch to be closed and the first matching switch to be opened, and obtaining a current negative DC bus voltage to obtain a fourth negative DC bus voltage; determining the positive DC bus insulation impedance and the negative DC bus insulation impedance according to the first negative DC bus voltage and the fourth negative DC bus voltage.

3. The insulation impedance detection method of claim 1, wherein, The insulation impedance detection circuit further comprises: a second matching resistor and a second matching switch; the second matching resistor and the second matching switch are connected in series between the positive DC bus and the ground wire; if the first negative DC bus voltage is less than a first preset value, the first unbalanced bridge switch is controlled to be closed, the second unbalanced bridge switch is controlled to be opened and the first matching switch is controlled to be closed, and a current negative DC bus voltage is obtained to obtain a second negative DC bus voltage; the first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed and the first matching switch is controlled to be opened, and a current negative DC bus voltage is obtained to obtain a third negative DC bus voltage, which comprises: If the first negative DC bus voltage is less than the first preset value, the first unbalanced bridge switch is controlled to be closed, the second unbalanced bridge switch is controlled to be opened, the first matching switch is controlled to be closed, and the second matching switch is controlled to be opened, and the current negative DC bus voltage is obtained to obtain a fifth negative DC bus voltage; The difference between the fifth negative DC bus voltage and the first negative DC bus voltage is determined; If the difference is less than a second preset value, the first unbalanced bridge switch is controlled to be closed, the second unbalanced bridge switch is controlled to be opened, the first matching switch is controlled to be closed, and the second matching switch is controlled to be closed, and the current negative DC bus voltage is obtained to obtain a second negative DC bus voltage; If the difference is not less than the second preset value, the fifth negative DC bus voltage is taken as the second negative DC bus voltage; The first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed, the first matching switch is controlled to be opened, and the second matching switch is controlled to be opened, and the current negative DC bus voltage is obtained to obtain a third negative DC bus voltage.

4. The insulation impedance detection method of claim 1, wherein, The second negative DC bus voltage and the third negative DC bus voltage are used to determine positive DC bus insulation impedance and negative DC bus insulation impedance, including: The voltage difference between the positive bus and the negative bus is obtained; The voltage difference between the positive bus and the negative bus is subtracted from the second negative DC bus voltage to obtain a second positive DC bus voltage; The voltage difference between the positive bus and the negative bus is subtracted from the third negative DC bus voltage to obtain a third positive DC bus voltage; The second positive DC bus voltage, the second negative DC bus voltage, the third positive DC bus voltage, and the third negative DC bus voltage are used to determine the positive DC bus insulation impedance and the negative DC bus insulation impedance.

5. The insulation impedance detection method of claim 4, wherein, The calculation formula of the positive DC bus insulation impedance and the negative DC bus insulation impedance is: wherein U 2+ is the second positive DC bus voltage, U 2- is the second negative DC bus voltage, U 3+ is the third positive DC bus voltage, U 3- is the third negative DC bus voltage, R x1 is the positive DC bus insulation impedance, R x2 is the negative DC bus insulation impedance, R0 is the value of the first balancing bridge resistance, R1 is the value of the first unbalancing bridge resistance, R2 is the value of the second unbalancing bridge resistance, R p1 is the value of the first matching resistance.

6. The insulation impedance detection method according to any one of claims 1 to 5, characterized in that, The first preset value is 30V.

7. An insulation impedance detection method characterized by comprising: The method is applied to an insulation impedance detection circuit, and the insulation impedance detection circuit includes a first balanced bridge resistor, a second balanced bridge resistor, a first unbalanced bridge resistor, a second unbalanced bridge resistor, a first unbalanced bridge switch, a second unbalanced bridge switch, a third matching resistor, and a third matching switch; the first balanced bridge resistor is connected between a positive DC bus and a ground line, and the second balanced bridge resistor is connected between a negative DC bus and the ground line; the first unbalanced bridge resistor and the first unbalanced bridge switch are connected in series between the positive DC bus and the ground line, the second unbalanced bridge resistor and the second unbalanced bridge switch are connected in series between the negative DC bus and the ground line, and the third matching resistor and the third matching switch are connected in series between the negative DC bus and the ground line; the method includes: The first unbalanced bridge switch is controlled to be opened, the second unbalanced bridge switch is controlled to be closed, and the third matching switch is controlled to be opened, and the current positive DC bus voltage is obtained to obtain a first positive DC bus voltage; If the first positive DC bus voltage is less than a first preset value, the first unbalanced bridge switch is controlled to be turned off, the second unbalanced bridge switch is controlled to be turned on, and the third matching switch is controlled to be turned on, and a current positive DC bus voltage is obtained to obtain a second positive DC bus voltage; the first unbalanced bridge switch is controlled to be turned on, the second unbalanced bridge switch is controlled to be turned off, and the third matching switch is controlled to be turned off, and the current positive DC bus voltage is obtained to obtain a third positive DC bus voltage; According to the second positive DC bus voltage and the third positive DC bus voltage, positive DC bus insulation impedance and negative DC bus insulation impedance are determined.

8. A detection device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the steps of the insulation impedance detection method according to any one of claims 1 to 6 or claim 7.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program is executed by the processor to implement the steps of the insulation impedance detection method according to any one of claims 1 to 6 or claim 7.

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