Energy storage cabinet and control method thereof

Abstract

This application provides an energy storage cabinet and its control method. In the energy storage cabinet: one end of the first switch is connected to the battery module and the insulation detection circuit, and the other end of the first switch is connected to the power conversion circuit. The second and third switches are connected between two busbar connection terminals and two DC terminals. The controller controls the detection switch to switch its state after controlling the first switch to open. During the switching process of the detection switch, the second and third switches remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC busbar and the voltage of the DC terminal to ground is less than a first voltage threshold, and the voltage difference between the second battery connection terminal and one busbar connection terminal is less than a second voltage threshold. This energy storage cabinet can detect the ground insulation impedance of the battery module when the second and third switches are closed, reducing manual operation steps, enabling timely maintenance of the ground insulation impedance of the battery module, and avoiding insulation detection failure. It has strong applicability.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to an energy storage cabinet and its control method. Background Technology

[0002] In an Uninterruptible Power Supply (UPS), the energy storage cabinet serves as a backup power source, supplying power to the DC bus inside the UPS during power grid outages to ensure continuous power supply to external loads. The energy storage cabinet includes battery modules, insulation detection circuitry, and protective switches. The battery modules exchange power with the DC bus. The energy storage cabinet uses the insulation detection circuitry to monitor changes in the battery modules' voltage to ground, determining the insulation performance of the battery modules. The protective switches disconnect the battery modules from the DC bus in abnormal situations to prevent the fault from escalating. Furthermore, to prevent control failures, the switching of the protective switches is typically performed manually by technicians, ensuring higher reliability.

[0003] Currently, to ensure that the UPS circuit design complies with electrical specifications and to prevent voltage reference point drift, the neutral line of the DC bus in the UPS is usually connected to the ground terminal through a power distribution line. This ensures that the voltages to ground of the positive and negative terminals of the DC bus remain equal to the phase voltages of the DC bus (i.e., the voltages of the positive and negative terminals of the DC bus relative to the neutral line). In this case, if the battery module remains connected to the DC bus, the voltage to ground of the battery module will also remain equal to the phase voltage of the DC bus, making it impossible for the insulation detection circuit to detect changes in the battery module's voltage to ground, thus causing the insulation detection to fail. Therefore, technicians typically manually disconnect the aforementioned protective switch before the insulation detection circuit operates to prevent the DC bus voltage from affecting the insulation detection results.

[0004] However, since the switching of the protective switch must be done manually by technicians, the insulation detection circuit can only perform the detection of the battery module under manual operation. The detection cycle of the insulation detection circuit is limited, which means that the insulation performance of the battery module to ground cannot be inspected and maintained in a timely manner. Summary of the Invention

[0005] This application provides an energy storage cabinet and its control method. The energy storage cabinet can detect the ground insulation impedance of the battery module while the protection switch remains closed, reducing manual operation steps and enabling timely inspection and maintenance of the battery module's ground insulation impedance. It also avoids insulation detection failure and has strong applicability.

[0006] In a first aspect, this application provides an energy storage cabinet, which includes a controller, a battery module, an insulation detection circuit, a power conversion circuit, a first switch, a second switch, and a third switch. The first electrode of the battery module is connected to a first terminal of the insulation detection circuit and a first battery connection terminal of the power conversion circuit. The second electrode of the battery module is connected to a second terminal of the insulation detection circuit and a terminal of the first switch. The other terminal of the first switch is connected to the second battery connection terminal of the power conversion circuit. The third terminal of the insulation detection circuit is connected to ground. The second and third switches are connected between two busbar connection terminals of the power conversion circuit and two DC terminals of the energy storage cabinet. The two DC terminals are respectively connected using… The circuit connects the positive and negative terminals of the DC busbar; the insulation detection circuit includes at least one detection switch; the controller is used to control the detection switch to switch state during the process of detecting the insulation impedance of the battery module to ground through the insulation detection circuit; the controller is also used to control the first switch to open, and control the detection switch to switch state after the first switch is opened; during the process of the detection switch switching state, the second switch and the third switch remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC busbar and the voltage of the DC terminal to ground is less than a first voltage threshold, and the voltage difference between the second battery connection terminal and a busbar connection terminal is less than a second voltage threshold.

[0007] In this embodiment, the controller controls the detection switch to switch its state after the first switch is opened. This means that the controller detects the battery module's insulation resistance to ground through the insulation detection circuit after the first switch is opened. For example, by controlling the detection switch to switch its state, the controller can adjust the resistance value inside the insulation detection circuit, causing a change in the voltage to ground at the second terminal of the insulation detection circuit. The magnitude of this voltage is also related to the battery module's insulation resistance to ground. Therefore, the controller can deduce and calculate the battery module's insulation resistance to ground based on the resistance value of the insulation detection circuit and the change in the voltage to ground at the second terminal. The purpose of the controller opening the first switch first is to prevent the voltage to ground at the second terminal of the insulation detection circuit from remaining constant during insulation detection, thus preventing insulation detection failure. Specifically, when the difference between the voltage of each DC terminal relative to the neutral line of the DC busbar and the DC terminal's voltage to ground is less than a first voltage threshold, it indicates that the neutral line of the DC busbar is connected to ground. When the voltage difference between the second battery connection terminal and a busbar connection terminal is less than the second voltage threshold, it indicates that the voltage at the second battery connection terminal is approximately equal to the voltage at the first busbar connection terminal. At this time, if the second and third switches remain closed, the voltage to ground at the second battery connection terminal is equal to the voltage to ground at the DC bus. Since the voltage to ground at the DC bus remains constant when the neutral line is connected to the ground terminal, the voltage to ground at the second battery connection terminal remains constant. In this case, the controller controls the first switch to open, which can prevent the voltage to ground at the second terminal of the insulation detection circuit from being affected by the voltage at the second battery connection terminal and thus remaining constant, avoiding insulation failure. At the same time, the second and third switches, as protective switches, can still be controlled manually, ensuring the safety of the energy storage cabinet and the reliability of the protective switch control. Therefore, in this embodiment, the controller can detect the insulation impedance to ground of the battery module while the protective switches (i.e., the second and third switches) remain closed, reducing the steps of manual operation, enabling the controller to inspect and maintain the insulation impedance to ground of the battery module at any time, and avoiding insulation detection failure, thus demonstrating strong applicability.

[0008] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The energy storage cabinet also includes an auxiliary power circuit. The first power input terminal and the second power input terminal of the auxiliary power circuit are respectively connected to the positive terminal of the battery module and the first busbar connection terminal. The first power output terminal and the second power output terminal of the auxiliary power circuit are respectively connected to the negative terminal of the battery module and the second busbar connection terminal. The positive terminal of the battery module is one of the first electrode and the second electrode, and the negative terminal of the battery module is the other of the first electrode and the second electrode. The auxiliary power circuit is used to supply power to the insulation detection circuit.

[0009] In this embodiment, the auxiliary power supply circuit can obtain electrical energy from the battery module through the first power input terminal and the first power output terminal as an energy source to power the insulation detection circuit. Alternatively, the auxiliary power supply circuit can obtain electrical energy from the two busbar connection terminals of the power conversion circuit through the second power input terminal and the second power output terminal as an energy source to power the insulation detection circuit. The electrical energy provided by the two busbar connection terminals of the power conversion circuit can be provided by a DC bus, or it can be obtained by the power conversion circuit through conversion based on the electrical energy provided by the battery module. In this embodiment, the auxiliary power supply circuit has a flexible and highly applicable method for obtaining electrical energy.

[0010] In one possible implementation, the energy storage cabinet further includes a fourth switch and a fifth switch, wherein the fourth switch is connected between the positive terminal of the battery module and the first power input terminal, and the fifth switch is connected between the negative terminal of the battery module and the first power output terminal. The controller is used to control the first switch, the fourth switch, and the fifth switch to open, and after the first switch, the fourth switch, and the fifth switch are opened, it controls the detection switch to switch the state.

[0011] In this embodiment, the controller first disconnects the fourth and fifth switches before detecting the battery module's insulation resistance to ground. This is to ensure that during the auxiliary power circuit's energy acquisition process, current can only enter through the second power input terminal and exit through the second power output terminal, thereby improving the accuracy of insulation detection. For example, when the positive and negative terminals of the DC busbar are connected to the DC busbar neutral line via a power device, and the DC busbar neutral line is connected to ground, the current output from the auxiliary power circuit can flow through the power device to the insulation detection circuit because both the power device and the insulation detection circuit are connected to ground. For instance, when current enters from the second power input terminal and exits from the first power output terminal, this current can flow through the insulation detection circuit and the external power device to form a current loop, thus affecting the voltage to ground at the second terminal of the insulation detection circuit. Therefore, in this embodiment, the controller first disconnects the first, fourth, and fifth switches to avoid insulation detection failure and simultaneously improve the accuracy of detecting the battery module's insulation resistance to ground.

[0012] In one possible implementation, the energy storage cabinet further includes a fourth switch and a fifth switch, wherein the fourth switch is connected between the first busbar connection terminal and the second power input terminal, and the fifth switch is connected between the second busbar connection terminal and the second power output terminal. The controller is used to control the first switch, the fourth switch, and the fifth switch to open, and after the first switch, the fourth switch, and the fifth switch are opened, it controls the detection switch to switch the state.

[0013] In this embodiment, the controller first disconnects the fourth and fifth switches before detecting the battery module's insulation resistance to ground. This is to ensure that during the auxiliary power circuit's energy acquisition process, current can only enter through the first power input terminal and exit through the first power output terminal, thereby improving the accuracy of insulation detection. For example, when the positive and negative terminals of the DC busbar are connected to the DC busbar neutral line via a power device, and the DC busbar neutral line is connected to ground, the current output from the auxiliary power circuit can flow through the power device to the insulation detection circuit because both the power device and the insulation detection circuit are connected to ground. For instance, when current enters from the first power input terminal and exits from the second power output terminal, this current can flow through the external power device and the insulation detection circuit to form a current loop, thus affecting the ground voltage at the second terminal of the insulation detection circuit. Therefore, in this embodiment, the controller first disconnects the first, fourth, and fifth switches to avoid insulation detection failure and simultaneously improve the accuracy of detecting the battery module's insulation resistance to ground.

[0014] In one possible implementation, the energy storage cabinet further includes a fourth switch, a fifth switch, a sixth switch, and a seventh switch. The fourth switch is connected between the positive terminal of the battery module and the first power input terminal, the fifth switch is connected between the negative terminal of the battery module and the first power output terminal, the sixth switch is connected between the first busbar connection terminal and the second power input terminal, and the seventh switch is connected between the second busbar connection terminal and the second power output terminal. The controller is used to open the first, fourth, and fifth switches while keeping the sixth and seventh switches closed, and to control the detection switch to switch its state after the first, fourth, and fifth switches are opened; or, The controller is used to open the first, sixth, and seventh switches while keeping the fourth and fifth switches closed, and to control the detection switch to switch the state after the first, sixth, and seventh switches are opened.

[0015] In this embodiment, the controller can either open the fourth and fifth switches and close the sixth and seventh switches before detecting the battery module's insulation impedance to ground, or close the fourth and fifth switches and open the sixth and seventh switches. Both control methods aim to improve the accuracy of insulation detection. The controller can flexibly select between the two control methods according to the needs of the actual application scenario. For example, when the battery module has sufficient power, the controller can close the fourth and fifth switches and open the first, sixth, and seventh switches before performing insulation detection. This allows the auxiliary power circuit to obtain power from the battery module for supply, avoids insulation detection failure, and improves the accuracy of detecting the battery module's insulation impedance to ground.

[0016] In one possible implementation, the auxiliary power supply circuit includes a first diode, a second diode, a third diode, a fourth diode, and a transformer module, the transformer module including a primary winding; the first diode is connected between the first power input terminal and one end of the primary winding, the second diode is connected between the second power input terminal and one end of the primary winding, the third diode is connected between the first power output terminal and the other end of the primary winding, and the fourth diode is connected between the second power output terminal and the other end of the primary winding.

[0017] In this embodiment, because the first and second diodes have unidirectional conduction properties, the auxiliary power supply can automatically select the electrical energy with the higher supply voltage as its power source. For example, when the supply voltage of the battery module is higher than the supply voltage of the busbar connection terminal of the power conversion circuit, the electrical energy provided by the battery module can flow through the first power input terminal, through the first diode, and then to the primary coil, thereby providing power to the auxiliary power circuit. Simultaneously, the third and fourth diodes can prevent reverse current flow, which could damage the auxiliary power circuit. The auxiliary power circuit provided in this embodiment has a simple structure, is easy to implement, and has high reliability.

[0018] In one possible implementation, the positive and negative terminals of the power supply of the insulation detection circuit are respectively connected to the first power supply terminal and the first reference ground terminal of the auxiliary power supply circuit; when the energy storage cabinet also includes at least one power auxiliary circuit, and the auxiliary power supply circuit is used to supply power to the power auxiliary circuit, the positive and negative terminals of the power supply of the power auxiliary circuit are respectively connected to the second power supply terminal and the second reference ground terminal of the auxiliary power supply circuit, and the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to a third voltage threshold.

[0019] In this embodiment, when the auxiliary power supply circuit simultaneously supplies power to both the insulation detection circuit and the power auxiliary circuit, the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to the third voltage threshold. This avoids the power auxiliary power supply affecting the voltage-to-ground changes of the insulation detection circuit, thereby further improving the accuracy of insulation detection. Specifically, the voltage difference between the first and second reference ground terminals being greater than or equal to the third voltage threshold means that the voltages between the first and second reference ground terminals are not equal, i.e., the first and second reference ground terminals are not equivalently connected. This avoids voltage-to-ground changes at the second terminal of the insulation detection circuit caused by the equivalent connection of the insulation detection circuit and the power auxiliary circuit, thereby improving the accuracy of insulation detection.

[0020] In one possible implementation, at least one power auxiliary circuit includes a bus voltage detection circuit and a bus voltage stabilizing circuit, wherein the bus voltage detection circuit is connected between the first busbar connection terminal and the second busbar connection terminal; and the bus voltage stabilizing circuit is connected between the first busbar connection terminal and the second busbar connection terminal.

[0021] In this embodiment, the controller can detect the voltage between the two busbar connection terminals of the power conversion circuit through the busbar voltage detection circuit. Furthermore, when the controller detects that the voltage between the two busbar connection terminals is unstable, it can stabilize the voltage between the two busbar connection terminals through the busbar voltage stabilization circuit, which has high reliability.

[0022] In one possible implementation, the insulation detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and two detection switches, the two detection switches being a first detection switch and a second detection switch; the first resistor and the second resistor are connected in series between a first terminal and a third terminal of the insulation detection circuit, the third resistor and the fourth resistor are connected in series between a second terminal and a third terminal of the insulation detection circuit; the first detection switch and the second resistor are connected in parallel, and the second detection switch and the third resistor are connected in parallel. During the process of detecting the battery module's insulation resistance to ground through the insulation detection circuit, the controller controls the detection switch to switch its state, specifically including: The first detection switch is controlled to switch from open to closed, while the second detection switch remains open. After the first detection switch is closed, the first detection switch is controlled to switch from closed to open, while the second detection switch is controlled to switch from open to closed.

[0023] In this embodiment, the controller adjusts the resistance value inside the insulation detection circuit by controlling the switching states of the first and second detection switches, thereby changing the voltage to ground at the second terminal of the insulation detection circuit. For example, when the first detection switch is closed and the second detection switch is open, the voltage to ground at the second terminal of the insulation detection circuit is related to the first, third, and fourth resistors, as well as the insulation impedance to ground of the battery module. When the first detection switch is open and the second detection switch is closed, the voltage to ground at the second terminal of the insulation detection circuit is related to the first, second, and fourth resistors, as well as the insulation impedance to ground of the battery module. Therefore, by detecting the change in the voltage to ground at the second terminal of the insulation detection circuit, the controller can deduce and calculate the insulation impedance to ground of the battery module, achieving a simple implementation principle.

[0024] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the positive terminal of the battery module, the second electrode is the negative terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the second busbar connection terminal.

[0025] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the negative terminal of the battery module, the second electrode is the positive terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the first busbar connection terminal.

[0026] In this embodiment, when the busbar connection terminal with a voltage difference less than the second voltage threshold is the second busbar connection terminal, the second electrode connected to the first switch is the negative electrode of the battery module, and the first electrode is the positive electrode of the battery module. Alternatively, when the busbar connection terminal with a voltage difference less than the second voltage threshold is the first busbar connection terminal, the second electrode connected to the first switch is the positive electrode of the battery module, and the first electrode is the negative electrode of the battery module. Therefore, this embodiment is applicable to various application scenarios and has strong applicability.

[0027] In one possible implementation, the energy storage cabinet also includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the positive terminal of the battery module, and the other end of which is connected to the first battery connection terminal. The controller is also used to control the first switch and the eighth switch to disconnect, and after the first switch and the eighth switch are disconnected, to control the detection switch to switch the state.

[0028] In this embodiment, the controller disconnects the eighth switch before detecting the battery module's insulation impedance to ground. This disconnects the first terminal of the insulation detection circuit from the first battery connection terminal, preventing the voltage at the first battery connection terminal from affecting the insulation detection circuit's ground impedance changes and improving the accuracy of the insulation detection. Furthermore, when a fault occurs in the battery module or power conversion circuit, the controller can disconnect both the first and eighth switches, ensuring a complete break between the battery module and the power conversion circuit, thus ensuring high reliability.

[0029] In one possible implementation, the energy storage cabinet also includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the negative terminal of the battery module, and the other end of which is connected to the first battery connection terminal of the power conversion circuit. The controller is also used to control the first switch and the eighth switch to disconnect, and after the first switch and the eighth switch are disconnected, to control the detection switch to switch the state.

[0030] In this embodiment, the controller disconnects the eighth switch before detecting the battery module's insulation impedance to ground. This disconnects the first terminal of the insulation detection circuit from the first battery connection terminal, preventing the voltage at the first battery connection terminal from affecting the insulation detection circuit's ground impedance changes and improving the accuracy of the insulation detection. Furthermore, when a fault occurs in the battery module or power conversion circuit, the controller can disconnect both the first and eighth switches, ensuring a complete break between the battery module and the power conversion circuit, thus ensuring high reliability.

[0031] In one possible implementation, the energy storage cabinet further includes a ninth switch, which is connected between the third busbar connection terminal of the power conversion circuit and the neutral terminal of the energy storage cabinet. The neutral terminal is used to connect the neutral line of the DC busbar. During the detection of the switch switching state, the ninth switch remains closed, and the voltage to ground at the neutral terminal is less than the first voltage threshold.

[0032] In this embodiment, the third busbar connection terminal is used to connect to the neutral point of the power conversion circuit. When the voltage to ground of the neutral terminal is less than the first voltage threshold, it means that the neutral line voltage of the DC busbar connected to the neutral terminal is approximately equal to the ground voltage, i.e., the neutral line of the DC busbar is connected to the ground. In other words, the difference between the voltage of each DC terminal of the energy storage cabinet relative to the neutral line of the DC busbar and the voltage to ground of that DC terminal is less than the first voltage threshold. At this time, as described above, when the second, third, and ninth switches remain closed, if the voltage difference between the second battery connection terminal and a busbar connection terminal is less than the second voltage threshold, the voltage to ground of the second battery connection terminal will remain unchanged. In this case, to avoid insulation detection failure, the controller can first control the first switch to open while the second, third, and ninth switches remain closed, and then perform the insulation detection. Simultaneously, during the insulation detection process, the second, third, and ninth switches do not require manual switching by technicians, reducing manual operation steps and allowing the controller to detect the insulation performance of the battery module at any time through the insulation detection circuit, making it highly applicable.

[0033] Secondly, this application provides a control method for an energy storage cabinet, applied to an energy storage cabinet including a battery module, an insulation detection circuit, a power conversion circuit, a first switch, a second switch, and a third switch; the first electrode of the battery module is connected to a first terminal of the insulation detection circuit and a first battery connection terminal of the power conversion circuit; the second electrode of the battery module is connected to a second terminal of the insulation detection circuit and a terminal of the first switch; the other terminal of the first switch is connected to a second battery connection terminal of the power conversion circuit; and the third terminal of the insulation detection circuit is connected to ground; the second and third switches are connected between two busbar connection terminals of the power conversion circuit and two DC terminals of the energy storage cabinet, the two DC terminals being used to connect to the positive and negative terminals of the DC busbars, respectively; the insulation detection circuit includes at least one detection switch; the method includes: The first switch is turned off. After the first switch is opened, the insulation resistance to ground of the battery module is detected by the insulation detection circuit. During the process of detecting the insulation resistance to ground of the battery module by the insulation detection circuit, the detection switch is controlled to switch the state. During the process of the detection switch switching the state, the second and third switches remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC bus and the voltage of the DC terminal to ground is less than the first voltage threshold, and the voltage difference between the second battery connection terminal and a bus connection terminal is less than the second voltage threshold.

[0034] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The energy storage cabinet also includes an auxiliary power circuit. The first power input terminal and the second power input terminal of the auxiliary power circuit are respectively connected to the positive terminal of the battery module and the first busbar connection terminal. The first power output terminal and the second power output terminal of the auxiliary power circuit are respectively connected to the negative terminal of the battery module and the second busbar connection terminal. The positive terminal of the battery module is one of the first electrode and the second electrode, and the negative terminal of the battery module is the other of the first electrode and the second electrode. The auxiliary power circuit is used to supply power to the insulation detection circuit.

[0035] In one possible implementation, the energy storage cabinet further includes a fourth switch and a fifth switch, wherein the fourth switch is connected between the positive terminal of the battery module and the first power input terminal, and the fifth switch is connected between the negative terminal of the battery module and the first power output terminal; the method further includes: The first, fourth, and fifth switches are controlled to open, and after the first, fourth, and fifth switches are opened, the detection switch is controlled to switch the state.

[0036] In one possible implementation, the energy storage cabinet further includes a fourth switch and a fifth switch, wherein the fourth switch is connected between the first busbar connection terminal and the second power input terminal, and the fifth switch is connected between the second busbar connection terminal and the second power output terminal; the method further includes: The first, fourth, and fifth switches are controlled to open, and after the first, fourth, and fifth switches are opened, the detection switch is controlled to switch the state.

[0037] In one possible implementation, the energy storage cabinet further includes a fourth switch, a fifth switch, a sixth switch, and a seventh switch. The fourth switch is connected between the positive terminal of the battery module and the first power input terminal; the fifth switch is connected between the negative terminal of the battery module and the first power output terminal; the sixth switch is connected between the first busbar connection terminal and the second power input terminal; and the seventh switch is connected between the second busbar connection terminal and the second power output terminal. The method further includes: While keeping the sixth and seventh switches closed, the first, fourth, and fifth switches are opened, and after the first, fourth, and fifth switches are opened, the detection switch is switched to change its state; or, While keeping the fourth and fifth switches closed, the first, sixth, and seventh switches are opened, and after the first, sixth, and seventh switches are opened, the detection switch is switched to change its state.

[0038] In one possible implementation, the auxiliary power supply circuit includes a first diode, a second diode, a third diode, a fourth diode, and a transformer module, the transformer module including a primary winding; the first diode is connected between the first power input terminal and one end of the primary winding, the second diode is connected between the second power input terminal and one end of the primary winding, the third diode is connected between the first power output terminal and the other end of the primary winding, and the fourth diode is connected between the second power output terminal and the other end of the primary winding.

[0039] In one possible implementation, the positive and negative terminals of the power supply of the insulation detection circuit are respectively connected to the first power supply terminal and the first reference ground terminal of the auxiliary power supply circuit; when the energy storage cabinet also includes at least one power auxiliary circuit, and the auxiliary power supply circuit is used to supply power to the power auxiliary circuit, the positive and negative terminals of the power supply of the power auxiliary circuit are respectively connected to the second power supply terminal and the second reference ground terminal of the auxiliary power supply circuit, and the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to a third voltage threshold.

[0040] In one possible implementation, at least one power auxiliary circuit includes a bus voltage detection circuit and a bus voltage stabilizing circuit, wherein the bus voltage detection circuit is connected between the first busbar connection terminal and the second busbar connection terminal; and the bus voltage stabilizing circuit is connected between the first busbar connection terminal and the second busbar connection terminal.

[0041] In one possible implementation, the insulation detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and two detection switches, the two detection switches being a first detection switch and a second detection switch; the first resistor and the second resistor are connected in series between a first terminal and a third terminal of the insulation detection circuit, the third resistor and the fourth resistor are connected in series between a second terminal and a third terminal of the insulation detection circuit; the first detection switch and the second resistor are connected in parallel, and the second detection switch and the third resistor are connected in parallel. During the process of detecting the battery module's insulation resistance to ground through the insulation detection circuit, controlling the detection switch to switch its state specifically includes: The first detection switch is controlled to switch from open to closed, while the second detection switch remains open. After the first detection switch is closed, the first detection switch is controlled to switch from closed to open, while the second detection switch is controlled to switch from open to closed.

[0042] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the positive terminal of the battery module, the second electrode is the negative terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the second busbar connection terminal.

[0043] In one possible implementation, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the negative terminal of the battery module, the second electrode is the positive terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the first busbar connection terminal.

[0044] In one possible implementation, the energy storage cabinet further includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the positive terminal of the battery module, and the other end of which is connected to the first battery connection terminal; the method further includes: The first and eighth switches are controlled to open, and after the first and eighth switches are opened, the detection switch is controlled to switch the state.

[0045] In one possible implementation, the energy storage cabinet further includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the negative terminal of the battery module, and the other end of which is connected to the first battery connection terminal of the power conversion circuit; the method further includes: The first and eighth switches are controlled to open, and after the first and eighth switches are opened, the detection switch is controlled to switch the state.

[0046] In one possible implementation, the energy storage cabinet further includes a ninth switch, which is connected between the third busbar connection terminal of the power conversion circuit and the neutral terminal of the energy storage cabinet. The neutral terminal is used to connect the neutral line of the DC busbar. During the detection of the switch switching state, the ninth switch remains closed, and the voltage to ground at the neutral terminal is less than the first voltage threshold.

[0047] It should be understood that the implementations and beneficial effects of the above-mentioned aspects of this application can be referenced from each other. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of an application scenario for the energy storage cabinet provided in an embodiment of this application; Figure 2 A schematic diagram of the structure of a UPS provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of an energy storage cabinet provided in an embodiment of this application; Figure 4 This is a schematic diagram of the power conversion circuit provided in an embodiment of this application; Figure 5 This is a schematic diagram of the insulation detection circuit provided in an embodiment of this application; Figure 6 This is another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 7 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 8 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 9 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 10 A schematic diagram of the auxiliary power supply circuit provided in an embodiment of this application; Figure 11 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 12 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 13Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 14 Another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application; Figure 15 This is a schematic flowchart of a control method for an energy storage cabinet provided in an embodiment of this application. Detailed Implementation

[0049] The energy storage cabinet provided in this application is suitable for various application scenarios, such as communication base station power supply scenarios, data center power supply scenarios, new energy power supply scenarios, energy storage power supply scenarios, or high-voltage direct current transmission scenarios. The following explanation uses the application of the energy storage cabinet in a data center power supply scenario as an example.

[0050] Please see Figure 1 , Figure 1 This is a schematic diagram illustrating an application scenario of the energy storage cabinet provided in an embodiment of this application. Figure 1 As shown in the embodiment of this application, the energy storage cabinet is connected to the DC input terminal of the UPS, the AC power grid is connected to the AC input terminal of the UPS, and the AC output terminal of the UPS is connected to the server. When the AC power grid is operating stably, the UPS converts the AC power supplied by the AC power grid and outputs it to the server to provide power. When the AC power grid is abnormal, the UPS converts the DC power supplied by the energy storage cabinet and outputs it to the server to maintain continuous power supply to the server and ensure high availability of the data center.

[0051] The internal framework structure of the UPS can be found in [reference]. Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of a UPS provided in an embodiment of this application. Figure 2As shown, the UPS main input terminal i1 is connected to the AC power grid, and the UPS main output terminal o1 is connected to the server. The UPS internally includes a rectifier and an inverter. The rectifier is connected to the inverter via the UPS's DC bus, and the energy storage cabinet is connected to the positive terminal BUS+ and the negative terminal BUS- of this DC bus. When the AC power grid is stable, the UPS converts the AC power supplied by the AC power grid to the server through the rectifier and inverter. Simultaneously, the UPS supplies power to the energy storage cabinet through the DC bus, thereby charging the battery modules within the energy storage cabinet. When the AC power grid fails, the UPS converts the DC power supplied by the battery modules in the energy storage cabinet to the server through the inverter. Furthermore, to ensure that the UPS circuit design complies with electrical specifications and to prevent drift of the internal potential reference point, a neutral line N is also provided inside the UPS. This neutral line N is connected to the positive terminal BUS+ and the negative terminal BUS- of the DC bus through two capacitors, and can be used to characterize the neutral point between the positive and negative terminals of the DC bus. Furthermore, the neutral line N is also connected to the neutral line of the AC power grid through the neutral line input terminal n1 of the UPS, and connected to the neutral line of the server through the neutral line output terminal n2 of the UPS.

[0052] It should be noted that the neutral line N is typically connected to ground via a power distribution line to suppress electromagnetic interference from the UPS and provide a low-impedance path for leakage current, thereby improving the system safety of the UPS. When the neutral line N is connected to ground, the voltage of the neutral line N is approximately equal to the voltage at ground, meaning the voltage of the neutral line N relative to ground is close to zero. Therefore, the voltage of the positive terminal BUS+ of the DC bus to ground is equal to the voltage of the positive terminal BUS+ of the DC bus relative to the neutral line N, and the voltage of the negative terminal BUS- of the DC bus to ground is equal to the voltage of the negative terminal BUS- of the DC bus relative to the neutral line N. In this situation, as described in the background section, if the DC bus remains electrically connected to the battery modules in the energy storage cabinet, the energy storage cabinet will be unable to detect the insulation resistance to ground of the battery modules, resulting in insulation detection failure. Therefore, technicians must manually disconnect the energy storage cabinet's protection switch to disconnect the battery modules from the DC bus before detecting the insulation resistance to ground of the battery modules. However, since the protection switches of the energy storage cabinet are usually manually controlled by technicians, the insulation testing of the battery module can only be performed under manual operation, which limits the insulation testing cycle of the battery module. As a result, the insulation performance of the battery module cannot be inspected and maintained in a timely manner.

[0053] Based on this, this application provides an energy storage cabinet that can detect the ground insulation impedance of the battery module while the protection switch is closed, reducing the number of manual operation steps, enabling the energy storage cabinet to promptly inspect and maintain the ground insulation impedance of the battery module, and avoiding insulation detection failure, thus having strong applicability.

[0054] The above are merely examples of application scenarios for the energy storage cabinet provided in this application, and are not exhaustive. This application does not limit the application scenarios.

[0055] The following is combined with Figures 3 to 14 The working principle of the energy storage cabinet provided in this application is explained.

[0056] It should be noted that, in the embodiments of this application, on the one hand, in order to ensure the safe and stable charging and discharging process of the battery module, a corresponding neutral line can be provided inside the energy storage cabinet. On the other hand, in order to improve power density and reduce wiring costs, a neutral line may not be provided inside the energy storage cabinet. For ease of explanation, the following description will first take the case where the energy storage cabinet does not have a neutral line as an example.

[0057] Please see Figure 3 , Figure 3 This is a structural schematic diagram of an energy storage cabinet provided in an embodiment of this application. Figure 3 As shown, the energy storage cabinet 300 includes a battery module 310 and a power conversion circuit 320. The two battery connection terminals (first battery connection terminal ib1 and second battery connection terminal ib2) of the power conversion circuit 320 are respectively connected to the two electrodes (first electrode and second electrode) of the battery module 310. The two busbar connection terminals (busbar connection terminal ia1 and busbar connection terminal ia2) of the power conversion circuit 320 are respectively connected to the two DC terminals (DC terminal dc1 and DC terminal dc2) of the energy storage cabinet 300. The two DC terminals of the energy storage cabinet 300 are respectively used to connect to the positive and negative terminals of the DC busbar (e.g., ...). Figure 2 (BUS+ and BUS- are shown). The controller is used to control the power conversion circuit 320 to perform voltage conversion on the DC power transmitted between the battery module 310 and the DC bus. For example, during operation, the power conversion circuit 320 obtains DC power from the battery module 310 through the two battery connection terminals, performs voltage conversion on the DC power provided by the battery module 310, and outputs it to the DC bus to supply power to the DC bus. Alternatively, the power conversion circuit 320 obtains DC power from the DC bus through the two bus connection terminals, performs voltage conversion on the DC power provided by the DC bus, and outputs it to the battery module 310 to charge it.

[0058] For some feasible implementation methods, please refer to Figure 4 , Figure 4 This is a schematic diagram of a power conversion circuit provided in an embodiment of this application. Figure 4As shown, the power conversion circuit 400 includes a first capacitor C1, a second capacitor C2, an energy storage inductor L, and switching transistors Q1, Q2, Q3, and Q4. During operation, when switching transistors Q1 and Q2 remain in their switching states while switching transistors Q3 and Q4 are alternately turned on, the power conversion circuit 400 can boost the DC power input to the two battery connection terminals ib1 and ib2. Alternatively, when switching transistors Q3 and Q4 remain in their switching states while switching transistors Q1 and Q2 are alternately turned on, the power conversion circuit 400 can buck the DC power input to the two busbar connection terminals ia1 and ia2, thereby achieving voltage conversion for the DC power transmitted between the battery module and the DC busbar. Figure 4 The power conversion circuit 400 shown is merely an example and does not constitute a limitation on the embodiments of this application.

[0059] In this embodiment, the energy storage cabinet 300 also includes a second switch K2 and a third switch K3, which can be understood as the protective switches in the energy storage cabinet described above. The second switch K2 is connected between the busbar connection terminal ia1 and the DC terminal dc1, and the third switch K3 is connected between the busbar connection terminal ia2 and the DC terminal dc2 of the energy storage cabinet 300. Alternatively, the positions of the second switch K2 and the third switch K3 can be interchanged, which is not limited here. The second switch K2 and the third switch K3 are used to connect or disconnect the battery module 310 from the DC busbar to ensure the safe maintenance of the energy storage cabinet 300 or to respond to emergencies. For example, when the battery module 310 needs to be repaired or replaced, technicians manually control the second switch K2 and the third switch K3 to disconnect, physically isolating the battery module 310 from the DC busbar, thereby preventing the escalation of abnormal faults. The reason why the switching states of the second switch K2 and the third switch K3 need to be manually controlled is that, as protective switches, they are not intended for frequent daily switching, but rather to provide safety protection measures in specific maintenance or emergency scenarios. In this case, since the switching states of automatic switches rely on sensors and complex logic judgments, control failures may occur. Manual operation ensures that the switching states of the second switch K2 and the third switch K3 are determined based on the actual on-site conditions, resulting in high accuracy and avoiding misjudgments (such as mistaking normal voltage fluctuations for faults). Therefore, the manual control of the switching states of the second switch K2 and the third switch K3 in the energy storage cabinet 300 can avoid control failures and enhance reliability.

[0060] It should be noted that when the battery module 310 in the energy storage cabinet 300 experiences faults such as foreign object contact, component aging, or improper operation by personnel, the insulation resistance to ground of the battery module 310 may decrease. To ensure electrical safety, the energy storage cabinet 300 needs to periodically detect the insulation resistance to ground of the battery module 310 to determine whether the insulation performance of the battery module 310 is good. Therefore, in this embodiment, the energy storage cabinet 300 also includes a controller and an insulation detection circuit 330. The first terminal ix1 of the insulation detection circuit 330 is connected to the first electrode of the battery module 310, the second terminal ix2 is connected to the second electrode of the battery module 310, and the third terminal ix3 is connected to ground. The controller can detect the magnitude of the insulation resistance to ground of the battery module 310 through the insulation detection circuit 330. When the controller detects that the insulation resistance to ground of the battery module 310 is greater than a certain value, the insulation performance of the battery module 310 is good. Conversely, when the controller detects that the insulation resistance to ground of the battery module 310 is less than a certain value, the insulation performance of the battery module 310 deteriorates, requiring inspection and maintenance. Specifically, the controller can issue a warning message when it detects a deterioration in the insulation performance of the battery module 310 and automatically implement protective measures such as power-off to prevent the fault from escalating.

[0061] The ground insulation resistance of battery module 310 includes the ground insulation resistance Rx of the first electrode and the ground insulation resistance Ry of the second electrode. When the insulation performance of battery module 310 is good, both Rx and Ry will be greater than a certain value. Conversely, when both Rx and Ry are less than a certain value, it means that the insulation performance of both the first and second electrodes of battery module 310 has decreased, requiring maintenance of battery module 310. Alternatively, when Rx or Ry is less than a certain value, it means that the insulation performance of either the first or second electrode of battery module 310 has decreased, i.e., the ground insulation performance of one of the two electrodes of battery module 310 has decreased. In this case, battery module 310 also requires maintenance.

[0062] In this embodiment, the controller can detect Rx and Ry through the insulation detection circuit 330. The insulation detection circuit 330 is connected to the first and second electrodes of the battery module 310, so that the magnitudes of Rx and Ry can affect the magnitudes of the electrical parameters (such as voltage and current) of the insulation detection circuit 330. Therefore, the controller can deduce and calculate Rx and Ry by acquiring the changes in the electrical parameters of the insulation detection circuit 330.

[0063] Specifically, to help the controller detect Rx and Ry, the insulation detection circuit 330 contains at least one detection switch. When the controller controls this detection switch to switch its state, the internal circuit structure of the insulation detection circuit 330 changes, thereby causing a change in the electrical parameters of the insulation detection circuit 330. Furthermore, since the insulation detection circuit 330 is connected to the first and second electrodes, the change in the electrical parameters of the insulation detection circuit 330 is related to the magnitudes of Rx and Ry. Therefore, based on the change in the electrical parameters of the insulation detection circuit 330, the controller can derive equations related to Rx and Ry, and thus calculate Rx and Ry.

[0064] For example, in some feasible implementations, please refer to Figure 5 , Figure 5 This is a schematic diagram of the insulation detection circuit provided in an embodiment of this application. Figure 5 As shown, the insulation detection circuit 500 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first detection switch Kx1, and a second detection switch Kx2. R1 and R2 are connected in series between the first terminal ix1 and the third terminal ix3 of the insulation detection circuit 500. R3 and R4 are connected in series between the second terminal ix2 and the third terminal ix3 of the insulation detection circuit 500. Kx1 is connected to R2, and Kx2 is connected to R3 in parallel.

[0065] Before the controller detects the battery module's insulation impedance to ground via the insulation detection circuit 500, Kx1 and Kx2 remain open. Further, when the controller begins detection, it first switches Kx1 from open to closed and keeps Kx2 open. At this time, because R2 is short-circuited, the resistance between the first terminal ix1 and the third terminal ix3 of the insulation detection circuit 500 decreases, causing changes in the voltage U1 (i.e., the voltage to ground of the first terminal ix1) and the voltage U2 (i.e., the voltage to ground of the second terminal ix2) of the insulation detection circuit 500. Meanwhile, since Rx is connected in parallel with the first terminal ix1 and the third terminal ix3 of the insulation detection circuit 500, and Ry is connected in parallel with the second terminal ix2 and the third terminal ix3 of the insulation detection circuit 500, according to Ohm's law, the magnitude of U1 is related to the resistance values ​​of R1 and Rx, and the magnitude of U2 is related to the resistance values ​​of R3, R4, and Ry. Furthermore, according to Kirchhoff's laws, the current flowing from the first terminal ix1 to the third terminal ix3 is always equal to the current flowing from the second terminal ix2 to the third terminal ix3. Therefore, the controller can derive an equation related to the values ​​of U1, U2, R1, R3, R4, Rx, and Ry based on Ohm's law and Kirchhoff's laws. Further, after detecting U1 and U2, the controller switches Kx1 from closed to open and Kx2 from open to closed. At this point, because R3 is short-circuited, the resistance between the second terminal ix2 and the third terminal ix3 of the insulation detection circuit 500 decreases, causing U1 and U2 to change again. Similarly, the controller can detect the changed U1 and U2 and derive another equation related to the values ​​of U1, U2, R1, R2, R4, Rx, and Ry at this time. It is understood that in the above two equations, only Rx and Ry are unknowns; therefore, the controller can calculate the resistance values ​​of Rx and Ry by solving these two equations. It should be noted that the specific form of the above equations derived by the controller can be adjusted according to the needs of the actual application scenario. The above is only an example and does not constitute a limitation on the embodiments of this application.

[0066] Optionally, during the detection of Rx and Ry, the controller can first close the second detection switch while keeping the first detection switch open, and then open the second detection switch and close the first detection switch. In this process, the controller can also derive two equations related to Rx and Ry, thereby calculating the resistance values ​​of Rx and Ry.

[0067] In some feasible implementations, Figure 5The insulation detection circuit 500 shown can be equipped with only one detection switch (either a first detection switch or a second detection switch). The controller can switch the state of this detection switch, which can also change the voltage to ground at the first terminal ix1 and the second terminal ix2 of the insulation detection circuit 500, thereby deriving and calculating the insulation impedance to ground of the battery module. This application does not limit the circuit structure and working principle of the insulation detection circuit 500.

[0068] Therefore, in the process of detecting the insulation impedance to ground of the battery module, the controller can derive and calculate the insulation impedance to ground of the battery module, i.e., the insulation impedance to ground of the first electrode and the second electrode of the battery module, by controlling the switching state of the detection switch (such as the first detection switch or the second detection switch) in the insulation detection circuit and detecting the change in the voltage to ground at the first and second terminals of the insulation detection circuit. In some feasible implementations, the controller can also derive two equations related to the insulation impedance to ground of the battery module by detecting the change in the voltage to ground at the first terminal of the insulation detection circuit. Alternatively, the controller can also derive two equations related to the insulation impedance to ground of the battery module by detecting the change in the voltage to ground at the second terminal of the insulation detection circuit. For ease of understanding, the following explanation uses the controller detecting the change in the voltage to ground at the second terminal of the insulation detection circuit as an example.

[0069] For example, please refer to [the document / reference]. Figure 5 To enable the controller to detect changes in the voltage to ground at the second terminal ix2 of the insulation detection circuit 500, a voltage sampling module 510 is internally installed in the insulation detection circuit 500. The two input terminals of this voltage sampling module 510 are connected to the second terminal ix2 of the insulation detection circuit 500 and ground, respectively, and the output terminal of the voltage sampling module 510 is connected to the controller. The voltage sampling module 510 internally includes resistors R11, R12, R13, and R14, and an operational amplifier OP. During the operation of the insulation detection circuit 500, the operational amplifier OP generates a corresponding voltage signal based on the voltage difference between the non-inverting and inverting input terminals and transmits it to the controller. The controller can then determine the magnitude of the voltage to ground at the second terminal ix2 of the insulation detection circuit 500 based on this voltage signal output by the operational amplifier OP, thereby determining the change in the voltage to ground at the second terminal ix2 of the insulation detection circuit 500. Figure 5 The circuit structure and working principle of the voltage sampling module 510 shown are for illustrative purposes only and are not intended to be limiting.

[0070] In general, the controller changes the voltage to ground at both ends of the insulation detection circuit by switching the detection switch in the circuit. Based on this change in voltage, the controller can deduce and calculate the battery module's insulation impedance to ground. However, in some applications, even if the controller switches the detection switch, the voltage to ground at both ends of the insulation detection circuit may not change, preventing the controller from detecting the battery module's insulation impedance and causing insulation detection failure.

[0071] In practice, the applicant of this application has found that the reason for the insulation test failure is that when the neutral line of the DC bus connected to the energy storage cabinet is connected to the ground (e.g.) Figure 2 As shown, if the battery modules inside the energy storage cabinet are electrically connected to the DC bus, the voltage to ground of the first and second terminals of the insulation detection circuit will remain equal to the voltage to ground of the DC bus. The voltage to ground of the DC bus will remain unchanged when the neutral line is connected to the ground terminal, thus ensuring that the voltage to ground of the first and second terminals of the insulation detection circuit does not change.

[0072] To facilitate understanding, the following will be combined with Figures 2 to 5 The principle behind insulation detection failure is explained.

[0073] As described above, when the neutral line N of the DC busbar is connected to ground, the voltage to ground of the positive terminal BUS+ of the DC busbar remains equal to the phase voltage of BUS+ (i.e., the voltage of BUS+ relative to the neutral line N), and the voltage to ground of the negative terminal BUS- of the DC busbar remains equal to the phase voltage of BUS- (i.e., the voltage of BUS- relative to the neutral line N). Simultaneously, BUS+ and BUS- are connected to the two DC terminals of the energy storage cabinet, respectively. Therefore, the voltage to ground of the two DC terminals is equal to the voltage to ground of BUS+ and BUS-, respectively, which are also equal to the phase voltages of BUS+ and BUS-. The phase voltages of BUS+ and BUS- usually remain constant, so the voltage to ground of each DC terminal of the energy storage cabinet will also remain constant. Therefore, when the neutral line N of the DC busbar connected to the energy storage cabinet is connected to ground, the voltage to ground of each DC terminal of the energy storage cabinet will remain constant. Furthermore, since connecting the neutral line N to ground makes the voltage of the neutral line N equal to the ground voltage, the voltage of each DC terminal relative to the neutral line N is approximately equal to the voltage of that DC terminal relative to ground. Therefore, by checking whether the voltage of each DC terminal of the energy storage cabinet relative to the neutral line N is approximately equal to the voltage of that DC terminal relative to ground, technicians can determine whether the neutral line N of the DC busbar to which the energy storage cabinet is connected is connected to ground.

[0074] Specifically, in this embodiment, when the difference between the voltage of each DC terminal of the energy storage cabinet relative to the neutral line N and the voltage of that DC terminal relative to ground is less than a first voltage threshold, it means that the voltage of each DC terminal relative to the neutral line N is approximately equal to the voltage of that DC terminal relative to ground, i.e., it means that the neutral line N of the DC busbar is connected to ground. For example, when the voltage of DC terminal dc1 relative to ground and the voltage of DC terminal dc1 relative to the neutral line N are both less than the first voltage threshold, and the voltage of DC terminal dc2 relative to ground and the voltage of DC terminal dc2 relative to the neutral line N are both less than the first voltage threshold, it indicates that the neutral line N is connected to ground. The specific value of the first voltage threshold depends on the requirements of the actual application scenario and is not limited here. For example, the first voltage threshold is approximately equal to zero.

[0075] Therefore, when the difference between the voltage of each DC terminal of the energy storage cabinet relative to the neutral line N and the voltage of that DC terminal to ground is less than the first voltage threshold, and the neutral line N is connected to the ground terminal, the voltage of each DC terminal of the energy storage cabinet to ground remains unchanged. In this case, if the second switch K2 and the third switch K3 remain closed, since each DC terminal is electrically connected to its corresponding busbar connection terminal, the voltage of each busbar connection terminal to ground will also remain unchanged. Furthermore, at this time, if the voltage of the second battery connection terminal ib2 of the power conversion circuit is close to equal to the voltage of a busbar connection terminal, the voltage of the second battery connection terminal ib2 to ground will also remain unchanged. For example, as shown... Figure 4 As shown, the busbar connection terminal ia2 of the power conversion circuit is directly connected to the second battery connection terminal ib2. Therefore, if the voltage to ground at the busbar connection terminal ia2 remains constant, the voltage at the second battery connection terminal ib2 will also remain constant. Thus, technicians can determine whether the voltage to ground at the second battery connection terminal ib2 will remain constant by checking whether the neutral line N of the DC busbar connected to the energy storage cabinet is approximately equal to the voltage difference at one busbar connection terminal, with the second switch K2 and the third switch K3 remaining closed.

[0076] Specifically, in this embodiment, when the voltage difference between the second battery connection terminal ib2 and a busbar connection terminal of the energy storage cabinet is less than the second voltage threshold, it means that the voltage of the second battery connection terminal ib2 is approximately equal to the voltage of the busbar connection terminal, i.e., the voltage to ground of the second battery connection terminal ib2 will remain unchanged. For example, when the voltage difference between the second battery connection terminal ib2 and the busbar connection terminal ia2 is less than the second voltage threshold, it indicates that the voltages of the second battery connection terminal ib2 and the busbar connection terminal ia2 are approximately equal. Therefore, if the voltage to ground of the busbar connection terminal ia2 remains unchanged, the voltage to ground of the second battery connection terminal ib2 will also remain unchanged. The specific value of the second voltage threshold depends on the requirements of the actual application scenario and is not limited here. For example, the second voltage threshold is approximately equal to zero.

[0077] Furthermore, since the second battery connection terminal ib2 is used to connect to the second terminal ix2 of the insulation detection circuit, the voltage to ground of the second terminal ix2 of the insulation detection circuit will also remain unchanged if the voltage to ground of the second battery connection terminal ib2 remains constant. Moreover, when the voltage to ground of the second terminal ix2 of the insulation detection circuit remains constant, since the second terminal ix2 and the first terminal ix1 of the insulation detection circuit are respectively connected to the two electrodes of the battery module, the voltage to ground of the first terminal ix1 of the insulation detection circuit will also remain constant. In other words, since the voltages to ground of both the first terminal ix1 and the second terminal ix2 of the insulation detection circuit remain constant, the controller cannot detect changes in the voltages to ground of the first terminal ix1 and the second terminal ix2 of the insulation detection circuit, and therefore cannot determine the insulation impedance to ground of the battery module, leading to insulation detection failure.

[0078] In summary, when the voltage difference between the neutral line voltage of each DC terminal of the energy storage cabinet and the voltage to ground of the DC terminal is less than the first voltage threshold, it means that the neutral line of the DC bus is connected to ground, and the voltage to ground of each DC terminal will remain unchanged. At this time, if the second switch K2 and the third switch K3 remain closed, the voltage to ground of the two bus connection terminals of the power conversion circuit will also remain unchanged. Furthermore, if the voltage difference between the second battery connection terminal ib2 and a bus connection terminal is less than the second voltage threshold, it means that the second battery connection terminal ib2 is electrically connected to that bus connection terminal, and the voltage to ground of the second battery connection terminal ib2 will also remain unchanged. In this case, the voltage to ground of the first terminal ix1 and the second terminal ix2 of the insulation detection circuit will remain unchanged, leading to insulation detection failure.

[0079] To prevent insulation detection failure, the energy storage cabinet provided in this embodiment is also equipped with a first switch K1. For example... Figure 3As shown, one end of the first switch K1 is connected to the second electrode of the battery module and the second terminal ix2 of the insulation detection circuit, while the other end of the first switch K1 is connected to the second battery connection terminal ib2 of the power conversion circuit. When the first switch K1 is open, the second terminal ix2 of the insulation detection circuit is disconnected from the second battery connection terminal ib2. At this time, if the second switch K2 and the third switch K3 remain closed, keeping the voltage to ground of the second battery connection terminal ib2 constant, the voltage to ground of the second terminal ix2 of the insulation detection circuit will not be affected by the voltage to ground of the second battery connection terminal ib2, thus preventing the voltage to ground of the second terminal ix2 of the insulation detection circuit from remaining constant and avoiding the problem of insulation detection failure.

[0080] Therefore, in this embodiment, the controller first controls the first switch to open, and then controls the detection switch in the insulation detection circuit to switch its state after the first switch is open. This causes the voltage to ground at the first and second terminals of the insulation detection circuit to change when the detection switch switches its state. This allows the controller to determine the battery module's insulation impedance to ground based on the change in the voltage to ground at either the first or second terminal of the insulation detection circuit, preventing insulation detection failure. Simultaneously, during insulation detection, technicians do not need to manually control the second and third switches to open, reducing manual operation steps. This allows the controller to check the insulation performance of the battery module at any time through the insulation detection circuit, making it highly applicable.

[0081] In some feasible implementations, the first electrode is the positive electrode (Bat+) of the battery module, and the second electrode is the negative electrode (Bat-) of the battery module. The specific circuit structure inside the energy storage cabinet can be found in [reference needed]. Figure 6 As shown, Figure 6 Another structural schematic diagram of the energy storage cabinet provided in an embodiment of this application. Figure 6 In the energy storage cabinet 600, a battery module 610, a power conversion circuit 620, an insulation detection circuit 630, a second switch K2, and a third switch K3 are included. The power conversion circuit 620 has two busbar connection terminals: a first busbar connection terminal ia1 and a second busbar connection terminal ia2. The DC terminal dc1 connected to the first busbar connection terminal ia1 is used to connect to the positive terminal of the DC busbar, and the DC terminal dc2 connected to the second busbar connection terminal ia2 is used to connect to the negative terminal of the DC busbar. The second battery connection terminal ib2 of the power conversion circuit 620 is connected to the second terminal ix2 of the insulation detection circuit 630 and the negative terminal Bat- of the battery module via the first switch K1. The internal circuit structure and implementation principle of the power conversion circuit 620 are similar to those of the battery module. Figure 4 The power conversion circuit 400 shown is the same, and the internal circuit structure and implementation principle of the insulation detection circuit 630 are the same. Figure 5The insulation detection circuit shown is the same as that of 500, and will not be described in detail here.

[0082] It is understandable that since the second battery connection terminal ib2 and the second busbar connection terminal ia2 are directly connected through the wires inside the power conversion circuit 620, the voltages of the second battery connection terminal ib2 and the second busbar connection terminal ia2 are equal. At this time, as mentioned above, if the neutral line of the DC busbar connected to the energy storage cabinet is connected to ground, and the second switch K2 and the third switch K3 remain closed, the voltage to ground of the second terminal ix2 of the insulation detection circuit 630 will remain equal to the voltage to ground of the DC terminal dc2, leading to insulation detection failure. Therefore, the energy storage cabinet 600 also includes a first switch K1. This first switch K1 can disconnect the electrical connection between the second battery connection terminal ib2 and the second terminal ix2 of the insulation detection circuit 630 before the insulation detection circuit 630 starts working, thus preventing insulation detection failure. Figure 6 The implementation principle of the energy storage cabinet 600 shown can be found in the above. Figures 1 to 5 The specific implementation methods are not described in detail here.

[0083] Optionally, the energy storage cabinet 600 is also equipped with an eighth switch K8. For example... Figure 6 As shown, one end of the eighth switch K8 is connected to the positive terminal of the battery module 610 and the first terminal ix1 of the insulation detection circuit 630, while the other end of the eighth switch K8 is connected to the first battery connection terminal ib1 of the power conversion circuit 620. It should be noted that before the controller detects the insulation impedance to ground of the battery module 610 through the insulation detection circuit 630, the controller controls the eighth switch K8 to open, thus disconnecting the first terminal ix1 of the insulation detection circuit 630 from the first battery connection terminal ib1. This prevents the voltage at the first battery connection terminal ib1 from affecting the insulation impedance to ground of the insulation detection circuit 630 during the controller's detection process, improving the reliability of the insulation detection. Furthermore, in some application scenarios, when the battery module 610 or the power conversion circuit 620 malfunctions, the controller can ensure the disconnection of the battery module 610 from the power conversion circuit 620 by controlling both the first switch K1 and the eighth switch K8, ensuring high reliability.

[0084] In some feasible implementations, the first electrode is the negative electrode (Bat-) of the battery module, and the second electrode is the positive electrode (Bat+) of the battery module. The specific circuit structure inside the energy storage cabinet can be found in [reference needed]. Figure 7 As shown, Figure 7 This is another structural schematic diagram of the energy storage cabinet provided in an embodiment of this application. Figure 7In this circuit, the energy storage cabinet 700 includes a battery module 710, a power conversion circuit 720, an insulation detection circuit 730, a first switch K1, a second switch K2, and a third switch K3. The two busbar connection terminals of the power conversion circuit 720 are a first busbar connection terminal ia1 and a second busbar connection terminal ia2. The DC terminal dc1 connected to the first busbar connection terminal ia1 is used to connect to the positive terminal of the DC busbar, and the DC terminal dc2 connected to the second busbar connection terminal ia2 is used to connect to the negative terminal of the DC busbar. The second battery connection terminal ib2 of the power conversion circuit 720 is connected to the second terminal ix2 of the insulation detection circuit 730 and the positive terminal of the battery module 710 through the first switch K1. Simultaneously, the voltage difference between the second battery connection terminal ib2 and the first busbar connection terminal ia1 is less than the aforementioned second voltage threshold, meaning that the voltages of the second battery connection terminal ib2 and the first busbar connection terminal ia1 are approximately equal, and therefore, the second battery connection terminal ib2 and the first busbar connection terminal ia1 are effectively connected together.

[0085] Optionally, the energy storage cabinet 700 can be equipped with an eighth switch K8. Specifically, in Figure 7 In the energy storage cabinet 700 shown, one end of the eighth switch K8 is connected to the negative terminal of the battery module 710 and the first terminal ix1 of the insulation detection circuit 730, while the other end of the eighth switch K8 is connected to the first battery connection terminal ib1 of the power conversion circuit 720. As can be seen from the above, before the controller detects the ground insulation impedance of the battery module 710 through the insulation detection circuit 730, the controller controls the eighth switch K8 to open, thus disconnecting the first terminal ix1 of the insulation detection circuit 730 from the first battery connection terminal ib1. This prevents the voltage at the first battery connection terminal ib1 from affecting the ground insulation impedance of the insulation detection circuit 730 during the controller's detection process, improving the reliability of the insulation detection. Similarly, when the battery module 710 or the power conversion circuit 720 malfunctions, the controller can ensure the disconnection of the battery module 710 from the power conversion circuit 720 by controlling both the first switch K1 and the eighth switch K8, ensuring high reliability.

[0086] It should be noted that, unlike energy storage cabinet 600, in energy storage cabinet 700, the first switch K1 is connected to the positive terminal of battery module 710 (in energy storage cabinet 600, the first switch K1 is connected to the negative terminal of battery module 610). Furthermore, in energy storage cabinet 700, the busbar connection terminal with a voltage approximately equal to the second battery connection terminal ib2 is the first busbar connection terminal ia1 (in energy storage cabinet 600, the busbar connection terminal with a voltage approximately equal to the second battery connection terminal ib2 is the second busbar connection terminal ia2). Aside from this, the implementation principle of energy storage cabinet 700 is similar to that of energy storage cabinet 600, and will not be elaborated upon here.

[0087] For ease of understanding, the following explanation will use the example of the first electrode being the negative electrode Bat- of the battery module and the second electrode being the positive electrode Bat+ of the battery module.

[0088] In some feasible implementations, the energy storage cabinet is also equipped with at least one power auxiliary circuit, such as a bus voltage detection circuit and a bus voltage stabilization circuit. For details, please refer to [link to relevant documentation]. Figure 8 , Figure 8 This is another structural schematic diagram of the energy storage cabinet provided in this application embodiment. The energy storage cabinet 800 includes a battery module 810, a power conversion circuit 820, an insulation detection circuit 830, a bus voltage detection circuit 840, a bus voltage stabilization circuit 850, a first switch K1, a second switch K2, and a third switch K3. The bus voltage detection circuit 840 and the bus voltage stabilization circuit 850 are both located between the first busbar connection terminal ia1 and the second busbar connection terminal ia2 of the power conversion circuit 820. The controller can detect the voltage between the first busbar connection terminal ia1 and the second busbar connection terminal ia2 through the bus voltage detection circuit 840, and can regulate the voltage between the first busbar connection terminal ia1 and the second busbar connection terminal ia2 through the bus voltage stabilization circuit 850 to maintain stability, thereby improving the stability and safety of the energy storage cabinet 800 operation.

[0089] In some feasible implementations, to enable the insulation detection circuit 830 and power auxiliary circuits (i.e., the aforementioned bus voltage detection circuit 840 and bus voltage stabilizing circuit 850) in the energy storage cabinet 800 to operate, an auxiliary power supply circuit 860 is also provided inside the energy storage cabinet 800. The first power input terminal PSE1+ and the second power input terminal PSE2+ of the auxiliary power supply circuit 860 are respectively connected to the positive terminal of the battery module 810 and the first busbar connection terminal ia1. The first power output terminal PSE1- and the second power output terminal PSE2- of the auxiliary power supply circuit 860 are respectively connected to the negative terminal of the battery module 810 and the second busbar connection terminal ia2. The auxiliary power supply circuit 860 can obtain electrical energy from the battery module 810 through the first power input terminal PSE1+ and the first power output terminal PSE1-, or the auxiliary power supply circuit 860 can obtain electrical energy from the busbar connection terminal of the power conversion circuit through the second power input terminal PSE2+ and the second power output terminal PSE2-. It should be noted that the power supplied to the busbar connection terminal of the power conversion circuit can be provided by the DC busbar, or it can be obtained by converting the power supplied by the battery module and then outputting it. Furthermore, the auxiliary power supply circuit 860 converts the input power into voltage and outputs it to the insulation detection circuit 830 and the power auxiliary circuit, respectively, to supply power to the insulation detection circuit 830 and the power auxiliary circuit.

[0090] However, in some application scenarios, when the energy storage cabinet uses the same auxiliary power supply circuit to power both the insulation detection circuit and the power auxiliary circuit, the controller's detection of the battery module's insulation impedance to ground via the insulation detection circuit is inaccurate. In practice, the applicant of this application discovered that the inaccuracy in the controller's detected insulation impedance to ground stems from the fact that when the energy storage cabinet uses the same auxiliary power supply circuit to power both the insulation detection circuit and the power auxiliary circuit, if the reference ground terminals connected to the insulation detection circuit and the power auxiliary circuit are the same, the resistance in the insulation detection circuit will be in parallel with the resistance in the power auxiliary circuit. As can be seen from the above, the controller needs to derive and calculate the battery module's insulation impedance to ground based on the resistance value in the insulation detection circuit. However, the parallel connection of the resistance in the power auxiliary circuit and the resistance in the insulation detection circuit reduces the equivalent impedance of the insulation detection circuit, thus causing the controller's calculation of the insulation impedance to ground to be inaccurate.

[0091] For example, please refer to Figure 9 , Figure 9 This is another structural schematic diagram of the energy storage cabinet provided in this application embodiment. The energy storage cabinet 900 includes a battery module 910, an insulation detection circuit 920, a power auxiliary circuit 930, and a controller 940. The insulation detection circuit 920 internally includes a voltage sampling module 921. Va+ is the positive terminal of the power supply for the insulation detection circuit 920, Va- is the negative terminal of the power supply for the insulation detection circuit 920, Vb+ is the positive terminal of the power supply for the power auxiliary circuit 930, and Vb- is the negative terminal of the power supply for the power auxiliary circuit 930. The implementation principle of the voltage sampling module 921 is consistent with the specific implementation of the voltage sampling module 510 described above, and the specific implementation of the power auxiliary circuit 930 is similar to that of the voltage sampling module 510 described above, and will not be described in detail here.

[0092] It should be noted that when the energy storage cabinet 900 uses the same auxiliary power circuit to supply power to the insulation detection circuit 920 and the power auxiliary circuit 930, if the insulation detection circuit 920 and the power auxiliary circuit 930 are connected to the same reference ground, it means that the voltages Va- and Vb- are equal, i.e., Va- and Vb- are equivalently connected together. In this case, the resistor in the voltage sampling module 921 and the resistor in the power auxiliary circuit 930 are equivalently connected, thus reducing the equivalent impedance of the insulation detection circuit and causing the controller to detect inaccurate insulation impedance of the battery module to ground.

[0093] Therefore, in order to improve the accuracy of the ground insulation impedance detected by the controller, the energy storage cabinet provided in this application embodiment can ensure that the reference ground terminals connected to the insulation detection circuit and the power auxiliary circuit are different when the insulation detection circuit and the power auxiliary circuit are powered through the auxiliary power supply circuit.

[0094] Specifically, in some feasible implementations, the internal circuit structure of the auxiliary power source circuit can be found in [reference needed]. Figure 10 As shown, Figure 10 This is a schematic diagram of the auxiliary power supply circuit provided in an embodiment of this application. Figure 10 In this circuit, the auxiliary power supply circuit 1000 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, and a transformer module 1010. The transformer module 1010 includes a primary winding T1 and at least two secondary windings, such as secondary windings T2 and T3. Specifically, the first diode D1 is connected between the first power input terminal PSE1+ and one end of the primary winding T1; the second diode D2 is connected between the second power input terminal PSE2+ and one end of the primary winding T1; the third diode D3 is connected between the first power output terminal PSE1- and the other end of the primary winding T1; and the fourth diode D4 is connected between the second power output terminal PSE2- and the other end of the primary winding T1. Simultaneously, the primary winding T1 is coupled to the secondary windings T2 and T3. One end of the secondary coil T2 is connected to the positive terminal Va+ of the insulation detection circuit via the first power supply terminal Vcc1 of the auxiliary power supply circuit 1000, and the other end of the secondary coil T2 is connected to the negative terminal Va- of the insulation detection circuit via the first reference ground terminal GND1 of the auxiliary power supply circuit 1000. One end of the secondary coil T3 is connected to the positive terminal Vb+ of the power auxiliary circuit via the second power supply terminal Vcc2 of the auxiliary power supply circuit 1000, and the other end of the secondary coil T3 is connected to the negative terminal Vb- of the insulation detection circuit via the second reference ground terminal GND2 of the auxiliary power supply circuit 1000.

[0095] During the operation of the auxiliary power supply circuit 1000, current can be supplied to the primary coil T1 from either the first power input terminal PSE1+ or the second power input terminal. The primary coil T1 transfers electrical energy to the secondary coils T2 and T3 through electromagnetic induction, enabling the secondary coil T2 to supply power to the insulation detection circuit and the secondary coil T3 to supply power to the auxiliary power circuit. It is understood that the negative terminal Va- of the insulation detection circuit's power supply is connected to the first reference ground terminal GND1, while the negative terminal Vb- of the auxiliary power supply circuit is connected to the second reference ground terminal GND2. Therefore, when the voltages at the first reference ground terminal GND1 and the second reference ground terminal GND2 are not equal, it indicates that the reference ground terminals connected to the insulation detection circuit and the auxiliary power circuit are different. This avoids the resistance of the auxiliary power circuit affecting the resistance of the insulation detection circuit, improving the accuracy of the controller's detection of the battery module's insulation impedance to ground through the insulation detection circuit.

[0096] Specifically, in this embodiment, when the voltage difference between the first reference ground terminal GND1 and the second reference ground terminal GND2 is greater than or equal to a third voltage threshold, it indicates that the voltages of the first reference ground terminal GND1 and the second reference ground terminal GND2 are not equal. The specific value of the third voltage threshold can be flexibly adjusted according to the needs of the actual application scenario, and is not limited here.

[0097] In some applications, the positive or negative terminal of a DC busbar can be connected to the neutral line via a power device. For example, a UPS can install an insulation detection device between the positive and neutral lines of the DC busbar to check the insulation performance of the DC busbar. In this case, the applicant of this application discovered that the accuracy of the controller inside the energy storage cabinet in detecting the ground insulation impedance of the battery module may decrease. In practice, the applicant found that the reason for the decreased accuracy of the ground insulation impedance detected by the controller in this situation is that the power device connected to the DC busbar can be equivalently connected to the insulation detection circuit through the auxiliary power circuit in the energy storage cabinet, thereby changing the equivalent impedance of the insulation detection circuit, and consequently causing the controller to detect inaccurate ground insulation impedance through the insulation detection circuit.

[0098] To facilitate understanding of the principle behind the inaccurate ground insulation impedance detected by the controller through the insulation detection circuit, the following content combines... Figure 11 and Figure 12 Let's illustrate with examples.

[0099] like Figure 10 As shown, during the operation of the auxiliary power supply circuit 1000, the current input from the first power input terminal PSE1+ can be output from the first power output terminal PSE1- and the second power output terminal PSE2- after passing through the primary coil T1. Alternatively, the current input from the second power input terminal PSE2+ can be output from the first power output terminal PSE1- and the second power output terminal PSE2- after passing through the primary coil T1. Therefore, regardless of whether the auxiliary power supply circuit 1000 obtains power from the first power input terminal PSE1+ or the second power input terminal PSE2+, there will always be current output from the first power output terminal PSE1- and the second power output terminal PSE2-.

[0100] For some feasible implementation methods, please refer to Figure 11 ,exist Figure 11 In this context, Ra represents the equivalent impedance formed between the first busbar connection terminal ia1 and the second busbar connection terminal ia2 in the power auxiliary circuit (such as the aforementioned busbar voltage detection circuit or busbar voltage stabilization circuit) of the energy storage cabinet 1100; Rc is the equivalent impedance formed between the first busbar connection terminal ia1 and the ground terminal (the neutral line of the DC busbar is connected to the ground terminal); and Rb is the equivalent impedance formed between the second busbar connection terminal ia2 and the ground terminal. At this time, if... Figure 11 As shown, when the current supplied by the battery module 1110 is input from the first power input terminal PSE1+ and output from the second power output terminal PSE2-, this current can flow to the second busbar connection terminal ia2, then through Ra to Rc, and finally through Rc to the insulation detection circuit 1130. It is understandable that when this current flows through the third terminal ix3 to the second terminal ix2 of the insulation detection circuit 1130, it will affect the voltage to ground of the second terminal ix2 of the insulation detection circuit 1130. This causes the controller to detect an inaccurate voltage to ground at the second terminal ix2 of the insulation detection circuit 1130, resulting in an inaccurate detection of the battery module's insulation impedance to ground.

[0101] To improve the accuracy of insulation impedance, the energy storage cabinet 1100 provided in this embodiment is further equipped with a fourth switch K4 and a fifth switch K5. The fourth switch K4 is located between the first busbar connection terminal ia1 and the second power input terminal PSE2+, and the fifth switch K5 is located between the second busbar connection terminal ia2 and the second power output terminal PSE2-. It is understood that when the fourth switch K4 and the fifth switch K5 are open, the auxiliary power circuit 1140 can only obtain power through the first power input terminal PSE1+. At this time, because the fifth switch K5 is open, the current input to the first power input terminal PSE1+ cannot be output through the second power output terminal PSE2-. Figure 11 The current loop shown cannot be generated, thus avoiding any impact on the voltage to ground of the second terminal ix2 of the insulation detection circuit.

[0102] For some feasible implementation methods, please refer to Figure 12 ,exist Figure 12 In this context, Ra represents the equivalent impedance formed between the first busbar connection terminal ia1 and the second busbar connection terminal ia2 in the energy storage cabinet 1200; Rc is the equivalent impedance formed between the first busbar connection terminal ia1 and the ground terminal by the external power device; and Rb is the equivalent impedance formed between the second busbar connection terminal ia2 and the ground terminal by the external power device. At this time, as... Figure 12 As shown, when current is input from the second power input terminal PSE2+ and output from the first power output terminal PSE1-, this current can flow to the negative terminal Bat- of the battery module, then through the battery module 1210 to the insulation detection circuit 1230, and then through the ground terminal and Rb to the second busbar connection terminal ia2. It is understandable that when this current flows through the first terminal ix1 to the third terminal ix3 of the insulation detection circuit 1230, it will affect the ground voltage of the first terminal ix1 and the second terminal ix2 of the insulation detection circuit 1230. This causes the controller to detect an inaccurate ground voltage at the second terminal ix2 of the insulation detection circuit, resulting in an inaccurate detection of the battery module's ground insulation impedance.

[0103] Therefore, in order to improve the accuracy of the detection of the battery module's insulation impedance to ground, in this embodiment, the energy storage cabinet 1200 can place the fourth switch K4 between the positive terminal of the battery module 1210 and the first power input terminal PSE1+, and place the fifth switch K5 between the negative terminal of the battery module 1210 and the first power output terminal PSE1-. It is understood that when the fourth switch K4 and the fifth switch K5 are open, the auxiliary power circuit 1240 can only obtain power through the second power input terminal PSE2+. At this time, since the fifth switch K5 is open, the current input to the second power input terminal PSE2+ cannot be output through the first power output terminal PSE1-. Figure 12 The current loop shown cannot be generated, thus avoiding any impact on the voltage to ground of the second terminal ix2 of the insulation detection circuit.

[0104] Therefore, in this embodiment of the application, the controller first controls the fourth switch K4 and the fifth switch K5, and then controls the detection switch in the insulation detection circuit to switch the state after the fourth switch K4 and the fifth switch K5 are opened. This can prevent the voltage to ground of the second terminal ix2 of the insulation detection circuit from being affected by external power devices, thereby improving the accuracy of the controller in detecting the insulation impedance to ground of the battery module.

[0105] In some feasible implementations, to make the auxiliary power supply circuit obtain power more flexibly, the energy storage cabinet may be equipped with a fourth switch K4, a fifth switch K5, a sixth switch K6, and a seventh switch K7. For details, please refer to [link / reference needed]. Figure 13 , Figure 13 This is another structural schematic diagram of the energy storage cabinet provided in this application embodiment. The fourth switch K4 is located between the positive terminal of the battery module 1310 and the first power input terminal PSE1+, the fifth switch K5 is located between the negative terminal of the battery module 1310 and the first power output terminal PSE1-, the sixth switch K6 is located between the first busbar connection terminal ia1 and the second power input terminal PSE2+, and the seventh switch K7 is located between the second busbar connection terminal ia2 and the second power output terminal PSE2-. It can be understood that when the controller needs to control the auxiliary power supply circuit 1340 to obtain power from the busbar connection terminal of the power conversion circuit 1320 for power supply, the controller can control the fourth switch K4 and the fifth switch K5 to open, and the sixth switch K6 and the seventh switch K7 to close. At this time, the auxiliary power supply circuit 1340 can obtain power through the second power input terminal PSE2+, and because the fifth switch K5 is open, the current input to the second power input terminal PSE2+ cannot be output through the first power output terminal PSE1-. Figure 12The current loop shown cannot be generated, thus avoiding any impact on the ground voltage of the second terminal ix2 of the insulation detection circuit 1330. Alternatively, when the controller needs to control the auxiliary power supply circuit 1340 to obtain power from the battery module 1310, the controller can control the fourth switch K4 and the fifth switch K5 to close, and the sixth switch K6 and the seventh switch K7 to open. At this time, the auxiliary power supply circuit 1340 can obtain power through the first power input terminal PSE1+, and since the seventh switch K7 is open, the current input to the first power input terminal PSE1+ cannot be output through the second power output terminal PSE2-. Figure 12 The current loop shown cannot be generated, thereby avoiding any impact on the ground voltage of the second terminal ix2 of the insulation detection circuit 1330.

[0106] Therefore, by first closing the fourth and fifth switches K4 and K5 and opening the sixth and seventh switches K6 and K7, and then controlling the switching state of the detection switch in the insulation detection circuit 1330 after the fourth and fifth switches K4 and K5 are closed and the sixth and seventh switches K6 and K7 are opened, the controller can avoid affecting the ground voltage of the second terminal ix2 of the insulation detection circuit 1330. Alternatively, by first opening the fourth and fifth switches K5 and closing the sixth and seventh switches K6 and K7, and then controlling the switching state of the detection switch in the insulation detection circuit 1330 after the fourth and fifth switches K5 are open and the sixth and seventh switches K6 and K7 are closed, the controller can also avoid affecting the ground voltage of the second terminal ix2 of the insulation detection circuit 1330, thereby improving the accuracy of the controller in detecting the ground insulation impedance of the battery module 1310. Furthermore, the controller can control the auxiliary power supply circuit 1340 to obtain power from the busbar connection terminal of the battery module 1310 or the power conversion circuit 1320 according to actual needs, providing high flexibility.

[0107] In some feasible implementations, in order to improve the power density of the energy storage cabinet 1300, the aforementioned fourth switch K4, fifth switch K5, sixth switch K6 and seventh switch K7 can also be integrated inside the auxiliary power circuit 1340. Examples of each of these are not provided in this application.

[0108] It should be noted that the implementation principles of the battery module 1110, power conversion circuit 1120, and insulation detection circuit 1130 in the energy storage cabinet 1100, the battery module 1210, power conversion circuit 1220, and insulation detection circuit 1230 in the energy storage cabinet 1200, and the battery module 1310, power conversion circuit 1320, and insulation detection circuit 1330 in the energy storage cabinet 1300 can be found in the above descriptions. Figures 3 to 10 The specific implementation methods are not described in detail here.

[0109] It should be noted that, furthermore, when the aforementioned auxiliary power circuit or external power device is equivalently connected to the insulation detection circuit, and the equivalent impedance of the auxiliary power circuit or power device is connected in parallel with the battery module's insulation impedance to ground, the accuracy of the controller in detecting changes in the battery module's insulation impedance to ground will decrease due to the principle of resistive voltage division. For example, when the battery module's insulation impedance to ground drops from 2 megohms to 1 megohm, the controller may not be able to detect a significant decrease due to the resistive voltage division. Conversely, when the battery module's insulation impedance to ground drops from 2 megohms to 1 kilohm, the controller may only detect a significant decrease, which is detrimental to timely inspection and maintenance of the battery module. Therefore, in this embodiment of the application, by setting the reference ground terminals of the power auxiliary circuit and the insulation detection circuit to be different, and by controlling the switching states of the fourth, fifth, sixth and seventh switches, the energy storage cabinet can not only improve the accuracy of insulation detection, but also improve the precision of insulation detection. This allows the controller to detect when the insulation impedance of the battery module to ground begins to decrease, which is convenient for timely inspection and maintenance and has strong applicability.

[0110] In some feasible implementations, as can be seen from the above, in order to ensure the safe and stable charging and discharging process of the battery module, a corresponding neutral line can be installed inside the energy storage cabinet. In this case, the internal circuit structure of the energy storage cabinet can be found in [reference needed]. Figure 14 As shown, Figure 14 This is another structural schematic diagram of the energy storage cabinet provided in the embodiments of this application. Figure 14 The energy storage cabinet 1400 shown includes a battery module 1410, a power conversion circuit 1420, and an insulation detection circuit 1430. The third busbar connection terminal of the power conversion circuit 1420 is used to connect to the neutral terminal of the energy storage cabinet 1400 via the neutral line of the energy storage cabinet 1400. This third busbar connection terminal is used to connect to the neutral point of the power conversion circuit 1420, and the neutral terminal is used to connect to the neutral line of the DC busbar.

[0111] In this embodiment, the energy storage cabinet 1400 also includes a second switch K2, a third switch K3, and a ninth switch K9. The ninth switch K9 is located between the third busbar connection terminal and the neutral terminal dc3. Similar to the second and third switches K2 and K3, the ninth switch K9 can be understood as a protective switch within the energy storage cabinet 1400. Therefore, the switching state of the ninth switch K9 is typically operated manually by technicians.

[0112] It is understandable that if the neutral line of the DC busbar is connected to ground, the voltage to ground of the neutral terminal connected to the neutral line of the DC busbar will be close to zero. Simultaneously, the voltage of each DC terminal of the energy storage cabinet 1400 relative to the neutral line of the DC busbar will be close to equal to the voltage to ground of that DC terminal. Specifically, in this embodiment, when the voltage to ground of the neutral terminal of the energy storage cabinet 1400 is less than a first voltage threshold, it indicates that the voltage to ground of the neutral terminal is close to zero. At this time, the voltage difference between the voltage of each DC terminal of the energy storage cabinet 1400 relative to the neutral line of the DC busbar and the voltage to ground of that DC terminal will also be less than the first voltage threshold, meaning the neutral line of the DC busbar is connected to ground.

[0113] Therefore, regardless of whether a neutral line is provided in the energy storage cabinet 1400, as long as the neutral line of the DC busbar is connected to the ground, when the second switch K2, the third switch K3, and the ninth switch K9 remain closed, if the voltage difference between the second battery connection terminal ib2 and a busbar connection terminal is less than the aforementioned second voltage threshold, then, as mentioned above, the voltage to ground of the second battery connection terminal ib2 of the power conversion circuit 1420 will remain unchanged. To avoid insulation detection failure, the energy storage cabinet 1400 also includes a first switch K1. As mentioned above, by first controlling the first switch K1 to open, and then controlling the switching state of the detection switch in the insulation detection circuit 1430 after the first switch K1 is open, the voltage to ground of the first terminal ix1 and the second terminal ix2 of the insulation detection circuit 1430 can change when the detection switch switches to different states. This allows the controller to determine the ground insulation impedance of the battery module 1410 based on the change in the ground voltage of the first terminal ix1 or the second terminal ix2 of the insulation detection circuit 1430, thus preventing insulation detection failure. Meanwhile, during the insulation testing process, technicians do not need to manually control the second switch K2, the third switch K3, and the ninth switch K9 to disconnect, reducing the number of manual operation steps. This allows the controller to detect the insulation performance of the battery module 1410 at any time through the insulation testing circuit 1430, making it highly applicable.

[0114] It is understandable that the specific implementation principle of the energy storage cabinet 1400 is the same as described above. Figures 1 to 13 The specific implementation method of the energy storage cabinet is similar, and will not be described in detail here.

[0115] Please see Figure 15 , Figure 15 This is a flowchart illustrating a control method for an energy storage cabinet provided in an embodiment of this application. The control method for the energy storage cabinet provided in this embodiment is applicable to... Figures 1 to 14 In the specific implementation, the energy storage cabinet can be controlled by a controller within the cabinet. The control method for the energy storage cabinet may include the following steps: S101, Control the first switch to open.

[0116] It is understandable that the purpose of disconnecting the first switch of the energy storage cabinet is to prevent the voltage to ground at the second terminal of the insulation detection circuit from remaining unchanged during the insulation detection process, which would lead to the failure of the insulation detection.

[0117] For a detailed implementation of S101, please refer to the above. Figures 1 to 15 The implementation method of the energy storage cabinet will not be elaborated here.

[0118] S102. After the first switch is opened, the insulation resistance to ground of the battery module is detected by the insulation detection circuit, and during the process of detecting the insulation resistance to ground of the battery module by the insulation detection circuit, the detection switch is controlled to switch the state; wherein, during the process of the detection switch switching the state, the second switch and the third switch remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC bus and the voltage of the DC terminal to ground is less than the first voltage threshold, and the voltage difference between the second battery connection terminal and a bus connection terminal is less than the second voltage threshold.

[0119] It is understood that when the difference between the voltage of each DC terminal relative to the neutral line of the DC busbar and the voltage of the DC terminal to ground is less than the first voltage threshold, it indicates that the neutral line of the DC busbar is connected to ground. Furthermore, when the voltage difference between the second battery connection terminal and a busbar connection terminal is less than the second voltage threshold, it indicates that the voltage of the second battery connection terminal is approximately equal to the voltage of the first busbar connection terminal. In this case, if the second and third switches remain closed, the voltage to ground of the second battery connection terminal remains unchanged. To avoid insulation detection failure, the energy storage cabinet controls the first switch to open, which prevents the voltage to ground of the second terminal of the insulation detection circuit from being affected by the voltage of the second battery connection terminal and thus remaining unchanged. Simultaneously, the second and third switches, as protective switches, can still be controlled manually, ensuring safety and reliability. In this embodiment, the energy storage cabinet can detect the insulation impedance to ground of the battery module while the protective switches (i.e., the second and third switches) remain closed, reducing manual operation steps. This allows the energy storage cabinet to inspect and maintain the insulation impedance to ground of the battery module at any time, and avoids insulation detection failure, demonstrating strong applicability.

[0120] In an optional embodiment, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The energy storage cabinet also includes an auxiliary power circuit. The first power input terminal and the second power input terminal of the auxiliary power circuit are respectively connected to the positive terminal of the battery module and the first busbar connection terminal. The first power output terminal and the second power output terminal of the auxiliary power circuit are respectively connected to the negative terminal of the battery module and the second busbar connection terminal. The positive terminal of the battery module is one of the first electrode and the second electrode, and the negative terminal of the battery module is the other of the first electrode and the second electrode. The auxiliary power circuit is used to supply power to the insulation detection circuit.

[0121] It is understandable that the auxiliary power supply circuit obtains electrical energy from the battery module through the first power input and first power output terminals, or from the two busbar connection terminals of the power conversion circuit through the second power input and second power output terminals. The electrical energy provided by the two busbar connection terminals can be provided by the DC busbar, or it can be obtained by the power conversion circuit from the electrical energy provided by the battery module. Therefore, the auxiliary power supply circuit has a flexible and highly applicable method for obtaining electrical energy.

[0122] In an optional embodiment, the energy storage cabinet further includes a fourth switch and a fifth switch, the fourth switch being connected between the positive terminal of the battery module and the first power input terminal, and the fifth switch being connected between the negative terminal of the battery module and the first power output terminal; the method further includes: The first, fourth, and fifth switches are controlled to open, and after the first, fourth, and fifth switches are opened, the detection switch is controlled to switch the state.

[0123] Understandably, the energy storage cabinet controls the first, fourth, and fifth switches to disconnect before testing the battery module's insulation resistance to ground. This can prevent insulation testing failure and improve the accuracy of testing the battery module's insulation resistance to ground.

[0124] In an optional embodiment, the energy storage cabinet further includes a fourth switch and a fifth switch, wherein the fourth switch is connected between the first busbar connection terminal and the second power input terminal, and the fifth switch is connected between the second busbar connection terminal and the second power output terminal; the method further includes: The first, fourth, and fifth switches are controlled to open, and after the first, fourth, and fifth switches are opened, the detection switch is controlled to switch the state.

[0125] Understandably, the energy storage cabinet controls the first, fourth, and fifth switches to disconnect before testing the battery module's insulation resistance to ground. This can prevent insulation testing failure and improve the accuracy of testing the battery module's insulation resistance to ground.

[0126] In an optional embodiment, the energy storage cabinet further includes a fourth switch, a fifth switch, a sixth switch, and a seventh switch. The fourth switch is connected between the positive terminal of the battery module and the first power input terminal; the fifth switch is connected between the negative terminal of the battery module and the first power output terminal; the sixth switch is connected between the first busbar connection terminal and the second power input terminal; and the seventh switch is connected between the second busbar connection terminal and the second power output terminal. The method further includes: While keeping the sixth and seventh switches closed, the first, fourth, and fifth switches are opened, and after the first, fourth, and fifth switches are opened, the detection switch is switched to change its state; or, While keeping the fourth and fifth switches closed, the first, sixth, and seventh switches are opened, and after the first, sixth, and seventh switches are opened, the detection switch is switched to change its state.

[0127] Understandably, both control methods described above can improve the accuracy of insulation detection, and the energy storage cabinet can flexibly select between the two methods according to the needs of the actual application scenario. For example, when the battery module has sufficient power, the energy storage cabinet can control the fourth and fifth switches to close and the first, sixth, and seventh switches to open before performing insulation detection, so that the auxiliary power circuit can obtain power from the battery module for power supply, and can avoid insulation detection failure while improving the accuracy of insulation detection.

[0128] In an optional embodiment, the auxiliary power supply circuit includes a first diode, a second diode, a third diode, a fourth diode, and a transformer module, the transformer module including a primary winding; the first diode is connected between the first power input terminal and one end of the primary winding, the second diode is connected between the second power input terminal and one end of the primary winding, the third diode is connected between the first power output terminal and the other end of the primary winding, and the fourth diode is connected between the second power output terminal and the other end of the primary winding.

[0129] Understandably, because the first and second diodes have unidirectional conduction properties, the auxiliary power supply can automatically select the higher voltage as its power source. Meanwhile, the third and fourth diodes prevent reverse current flow, which could damage the auxiliary power circuit. The structure is simple and highly reliable.

[0130] In an optional embodiment, the positive and negative terminals of the power supply of the insulation detection circuit are respectively connected to the first power supply terminal and the first reference ground terminal of the auxiliary power supply circuit; when the energy storage cabinet also includes at least one power auxiliary circuit, and the auxiliary power supply circuit is used to supply power to the power auxiliary circuit, the positive and negative terminals of the power supply of the power auxiliary circuit are respectively connected to the second power supply terminal and the second reference ground terminal of the auxiliary power supply circuit, and the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to a third voltage threshold.

[0131] It is understandable that when the auxiliary power supply circuit supplies power to both the insulation detection circuit and the power auxiliary circuit, the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to the third voltage threshold. This can prevent the power auxiliary power supply from affecting the change in the voltage to ground of the insulation detection circuit, thereby further improving the accuracy of insulation detection.

[0132] In an optional embodiment, at least one power auxiliary circuit includes a bus voltage detection circuit and a bus voltage stabilizing circuit, wherein the bus voltage detection circuit is connected between the first busbar connection terminal and the second busbar connection terminal; and the bus voltage stabilizing circuit is connected between the first busbar connection terminal and the second busbar connection terminal.

[0133] Understandably, the energy storage cabinet can detect the voltage between the two busbar connection terminals of the power conversion circuit through the busbar voltage detection circuit. Furthermore, when the energy storage cabinet detects that the voltage between the two busbar connection terminals is unstable, it can stabilize the voltage between the two busbar connection terminals through the busbar voltage stabilization circuit, which has high reliability.

[0134] In an optional embodiment, the insulation detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and two detection switches, the two detection switches being a first detection switch and a second detection switch; the first resistor and the second resistor are connected in series between a first terminal and a third terminal of the insulation detection circuit, and the third resistor and the fourth resistor are connected in series between a second terminal and a third terminal of the insulation detection circuit; the first detection switch and the second resistor are connected in parallel, and the second detection switch and the third resistor are connected in parallel. During the process of detecting the battery module's insulation resistance to ground through the insulation detection circuit, controlling the detection switch to switch its state specifically includes: The first detection switch is controlled to switch from open to closed, while the second detection switch remains open. After the first detection switch is closed, the first detection switch is controlled to switch from closed to open, while the second detection switch is controlled to switch from open to closed.

[0135] It is understandable that the energy storage cabinet can adjust the resistance value inside the insulation detection circuit by controlling the switching states of the first and second detection switches, thereby changing the voltage to ground at the second terminal of the insulation detection circuit. This voltage is related to the internal resistors and the insulation impedance to ground of the battery module. Therefore, by detecting the change in the voltage to ground at the second terminal of the insulation detection circuit, the energy storage cabinet can deduce and calculate the insulation impedance to ground of the battery module, a simple implementation principle.

[0136] In an optional embodiment, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the positive terminal of the battery module, the second electrode is the negative terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the second busbar connection terminal.

[0137] In an optional embodiment, the two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the negative terminal of the battery module, the second electrode is the positive terminal of the battery module, and the busbar connection terminal with a voltage difference of less than a second voltage threshold is the first busbar connection terminal.

[0138] It is understandable that, when the busbar connection terminal with a voltage difference less than the second voltage threshold is the second busbar connection terminal, the second electrode connected to the first switch is the negative terminal of the battery module, and the first electrode is the positive terminal of the battery module. Alternatively, when the busbar connection terminal with a voltage difference less than the second voltage threshold is the first busbar connection terminal, the second electrode connected to the first switch is the positive terminal of the battery module, and the first electrode is the negative terminal of the battery module. Therefore, this embodiment is applicable to different application scenarios and has strong applicability.

[0139] In an optional embodiment, the energy storage cabinet further includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the positive terminal of the battery module, and the other end of which is connected to the first battery connection terminal; the method further includes: The first and eighth switches are controlled to open, and after the first and eighth switches are opened, the detection switch is controlled to switch the state.

[0140] In an optional embodiment, the energy storage cabinet further includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the negative terminal of the battery module, and the other end of which is connected to the first battery connection terminal of the power conversion circuit; the method further includes: The first and eighth switches are controlled to open, and after the first and eighth switches are opened, the detection switch is controlled to switch the state.

[0141] Understandably, by controlling the eighth switch to open before detecting the battery module's insulation resistance to ground, the energy storage cabinet disconnects the first terminal of the insulation detection circuit from the first battery connection terminal. This prevents the voltage at the first battery connection terminal from affecting the insulation detection circuit's ground resistance during insulation testing, thus improving the accuracy of the insulation detection. Furthermore, when a fault occurs in the battery module or power conversion circuit, the energy storage cabinet can ensure the disconnection of the battery module from the power conversion circuit by controlling both the first and eighth switches, ensuring high reliability.

[0142] In an optional embodiment, the energy storage cabinet further includes a ninth switch, which is connected between the third busbar connection terminal of the power conversion circuit and the neutral terminal of the energy storage cabinet. The neutral terminal is used to connect the neutral line of the DC busbar. During the detection of the switch switching state, the ninth switch remains closed, and the voltage to ground at the neutral terminal is less than the first voltage threshold.

[0143] It is understandable that when the voltage to ground at the neutral terminal is less than the first voltage threshold, it means that the neutral line voltage of the DC bus connected to the neutral terminal is approximately equal to the ground voltage, i.e., the neutral line of the DC bus is connected to ground. At this time, as mentioned above, when the second, third, and ninth switches remain closed, if the voltage difference between the second battery connection terminal and a bus connection terminal is less than the aforementioned second voltage threshold, the voltage to ground at the second battery connection terminal will remain unchanged. To avoid insulation detection failure, the energy storage cabinet can control the first switch to open while the second, third, and ninth switches remain closed, and then perform the insulation detection. Simultaneously, during the insulation detection process, the second, third, and ninth switches do not require manual switching by technicians, reducing manual operation steps and allowing the energy storage cabinet to continuously check the insulation performance of the battery modules through the insulation detection circuit, making it highly applicable.

[0144] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the above claims.

Claims

1. An energy storage cabinet, characterized in that, The energy storage cabinet includes a controller, a battery module, an insulation detection circuit, a power conversion circuit, a first switch, a second switch, and a third switch. The first electrode of the battery module is connected to a first terminal of the insulation detection circuit and a first battery connection terminal of the power conversion circuit. The second electrode of the battery module is connected to a second terminal of the insulation detection circuit and one terminal of the first switch. The other terminal of the first switch is connected to a second battery connection terminal of the power conversion circuit. The third terminal of the insulation detection circuit is connected to ground. The second and third switches are connected between two busbar connection terminals of the power conversion circuit and two DC terminals of the energy storage cabinet. The two DC terminals are respectively used to connect to the positive and negative terminals of the DC busbars. The insulation detection circuit includes at least one detection switch. The controller controls the switching state of the detection switch during the process of detecting the ground insulation impedance of the battery module through the insulation detection circuit. The controller is also configured to control the first switch to open, and after the first switch is opened, control the detection switch to switch state; During the switching process of the detection switch, the second switch and the third switch remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC bus and the voltage of the DC terminal relative to ground is less than a first voltage threshold, and the voltage difference between the second battery connection terminal and one of the bus connection terminals is less than a second voltage threshold.

2. The energy storage cabinet according to claim 1, characterized in that, The two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The energy storage cabinet also includes an auxiliary power circuit. The first power input terminal and the second power input terminal of the auxiliary power circuit are respectively connected to the positive terminal of the battery module and the first busbar connection terminal. The first power output terminal and the second power output terminal of the auxiliary power circuit are respectively connected to the negative terminal of the battery module and the second busbar connection terminal. The positive terminal of the battery module is one of the first electrode and the second electrode, and the negative terminal of the battery module is the other of the first electrode and the second electrode. The auxiliary power circuit is used to supply power to the insulation detection circuit.

3. The energy storage cabinet according to claim 2, characterized in that, The energy storage cabinet also includes a fourth switch and a fifth switch. The fourth switch is connected between the positive terminal of the battery module and the first power input terminal, and the fifth switch is connected between the negative terminal of the battery module and the first power output terminal. The controller is used to control the first switch, the fourth switch and the fifth switch to be disconnected, and after the first switch, the fourth switch and the fifth switch are disconnected, it controls the detection switch to switch the state.

4. The energy storage cabinet according to claim 2, characterized in that, The energy storage cabinet also includes a fourth switch and a fifth switch. The fourth switch is connected between the first busbar connection terminal and the second power input terminal, and the fifth switch is connected between the second busbar connection terminal and the second power output terminal. The controller is used to control the first switch, the fourth switch and the fifth switch to be disconnected, and after the first switch, the fourth switch and the fifth switch are disconnected, it controls the detection switch to switch the state.

5. The energy storage cabinet according to claim 2, characterized in that, The energy storage cabinet also includes a fourth switch, a fifth switch, a sixth switch, and a seventh switch. The fourth switch is connected between the positive terminal of the battery module and the first power input terminal. The fifth switch is connected between the negative terminal of the battery module and the first power output terminal. The sixth switch is connected between the first busbar connection terminal and the second power input terminal. The seventh switch is connected between the second busbar connection terminal and the second power output terminal. The controller is configured to, while keeping the sixth and seventh switches closed, control the first, fourth, and fifth switches to open, and, after the first, fourth, and fifth switches are opened, control the detection switch to switch its state; or... The controller is used to control the first switch, the sixth switch, and the seventh switch to open while keeping the fourth switch and the fifth switch closed, and to control the detection switch to switch state after the first switch, the sixth switch, and the seventh switch are opened.

6. The energy storage cabinet according to any one of claims 2 to 5, characterized in that, The auxiliary power supply circuit includes a first diode, a second diode, a third diode, a fourth diode, and a transformer module. The transformer module includes a primary winding. The first diode is connected between the first power input terminal and one end of the primary winding. The second diode is connected between the second power input terminal and one end of the primary winding. The third diode is connected between the first power output terminal and the other end of the primary winding. The fourth diode is connected between the second power output terminal and the other end of the primary winding.

7. The energy storage cabinet according to any one of claims 2 to 6, characterized in that, The positive and negative terminals of the power supply of the insulation detection circuit are respectively connected to the first power supply terminal and the first reference ground terminal of the auxiliary power supply circuit. When the energy storage cabinet further includes at least one power auxiliary circuit, and the auxiliary power supply circuit is used to supply power to the power auxiliary circuit, the positive and negative terminals of the power supply of the power auxiliary circuit are respectively connected to the second power supply terminal and the second reference ground terminal of the auxiliary power supply circuit, and the voltage difference between the first reference ground terminal and the second reference ground terminal is greater than or equal to a third voltage threshold.

8. The energy storage cabinet according to claim 7, characterized in that, The at least one power auxiliary circuit includes a bus voltage detection circuit and a bus voltage stabilizing circuit. The bus voltage detection circuit is connected between the first busbar connection terminal and the second busbar connection terminal; the bus voltage stabilizing circuit is connected between the first busbar connection terminal and the second busbar connection terminal.

9. The energy storage cabinet according to any one of claims 1 to 8, characterized in that, The insulation detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, and two detection switches. The two detection switches include a first detection switch and a second detection switch. The first resistor and the second resistor are connected in series between the first and third terminals of the insulation detection circuit. The third resistor and the fourth resistor are connected in series between the second and third terminals of the insulation detection circuit. The first detection switch and the second resistor are connected in parallel, and the second detection switch and the third resistor are connected in parallel. During the process of detecting the insulation impedance to ground of the battery module through the insulation detection circuit, the controller controls the detection switch to switch its state, specifically including: The system controls the first detection switch to switch from open to closed, while keeping the second detection switch open. After controlling the first detection switch to close, the system controls the first detection switch to switch from closed to open, and the second detection switch to switch from open to closed.

10. The energy storage cabinet according to any one of claims 1 to 9, characterized in that, The two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the positive terminal of the battery module, the second electrode is the negative terminal of the battery module, and the busbar connection terminal with a voltage difference of less than the second voltage threshold is the second busbar connection terminal.

11. The energy storage cabinet according to any one of claims 1 to 9, characterized in that, The two busbar connection terminals include a first busbar connection terminal and a second busbar connection terminal. The DC terminal connected to the first busbar connection terminal is used to connect to the positive terminal of the DC busbar, and the DC terminal connected to the second busbar connection terminal is used to connect to the negative terminal of the DC busbar. The first electrode is the negative terminal of the battery module, the second electrode is the positive terminal of the battery module, and the busbar connection terminal with a voltage difference of less than the second voltage threshold is the first busbar connection terminal.

12. The energy storage cabinet according to claim 10, characterized in that, The energy storage cabinet also includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the positive terminal of the battery module, and the other end of which is connected to the first battery connection terminal. The controller is also used to control the first switch and the eighth switch to disconnect, and after the first switch and the eighth switch are disconnected, to control the detection switch to switch state.

13. The energy storage cabinet according to claim 11, characterized in that, The energy storage cabinet also includes an eighth switch, one end of which is connected to the first terminal of the insulation detection circuit and the negative terminal of the battery module, and the other end of which is connected to the first battery connection terminal of the power conversion circuit. The controller is also used to control the first switch and the eighth switch to disconnect, and after the first switch and the eighth switch are disconnected, to control the detection switch to switch state.

14. The energy storage cabinet according to any one of claims 1 to 13, characterized in that, The energy storage cabinet also includes a ninth switch, which is connected between the third busbar connection terminal of the power conversion circuit and the neutral terminal of the energy storage cabinet. The neutral terminal is used to connect the neutral line of the DC busbar. During the switching process of the detection switch, the ninth switch remains closed, and the voltage to ground of the neutral terminal is less than the first voltage threshold.

15. A control method for an energy storage cabinet, applied to the energy storage cabinet, the energy storage cabinet comprising a battery module, an insulation detection circuit, a power conversion circuit, a first switch, a second switch, and a third switch; a first electrode of the battery module is connected to a first terminal of the insulation detection circuit and a first battery connection terminal of the power conversion circuit, a second electrode of the battery module is connected to a second terminal of the insulation detection circuit and a terminal of the first switch, the other terminal of the first switch is connected to a second battery connection terminal of the power conversion circuit, and a third terminal of the insulation detection circuit is connected to ground; the second switch and the third switch are connected between two busbar connection terminals of the power conversion circuit and two DC terminals of the energy storage cabinet, the two DC terminals being respectively used to connect to the positive and negative terminals of the DC busbars; the insulation detection circuit includes at least one detection switch; characterized in that... The method further includes: The first switch is to be turned off. After the first switch is opened, the insulation resistance to ground of the battery module is detected by the insulation detection circuit, and during the process of detecting the insulation resistance to ground of the battery module by the insulation detection circuit, the detection switch is controlled to switch the state; wherein, during the process of the detection switch switching the state, the second switch and the third switch remain closed, and the difference between the voltage of each DC terminal relative to the neutral line of the DC bus and the voltage of the DC terminal to ground is less than a first voltage threshold, and the voltage difference between the second battery connection terminal and one of the bus connection terminals is less than a second voltage threshold.

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