Power supply system and battery ground fault detection method

Abstract

A power supply system and a battery ground fault detection method. Voltage sampling is performed by using a sampling circuit existing inside each power module, so that application costs can be saved on without adding new detection devices. When it is determined that a voltage bias has occurred between a positive electrode and a negative electrode of a battery pack, and the voltage of the electrode on a single side of the battery pack approaches the voltage of a busbar on the same side, which indicates that a battery ground fault may have occurred, then a switch connected between a power supply port and an input terminal of a DC / DC circuit is turned off. Subsequently, the voltage at the power supply port is sampled, and if there is still a voltage bias between the positive electrode and the negative electrode of the battery pack, which indicates that a ground fault has occurred in the battery pack, then a battery ground fault alarm is generated, the battery ground fault is reported, and the switch remains off. The method can accurately locate and isolate the battery ground fault, thereby preventing the entire power supply system from shutting down due to the battery ground fault.

Description

A power supply system and a method for detecting battery grounding faults

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 202510213685.6, filed on February 25, 2025, entitled "A Power Supply System and a Battery Grounding Fault Detection Method", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of power electronics technology, and in particular to a power supply system and a method for detecting battery grounding faults. Background Technology

[0004] In several mainstream power distribution systems in data centers, the neutral (N) and grounding (PE) wires share a single cable or are directly connected. When a battery pack connected to a power supply system such as an uninterruptible power supply (UPS) experiences a ground fault (i.e., a short circuit occurs between the positive or negative terminal of the battery pack and the grounding wire), and the battery pack does not have a separate neutral wire, it will cause a voltage bias at the positive or negative terminal of the UPS battery pack. The energy from the battery pack will then directly flow into the DC bus of all power modules connected to that battery pack, causing all power modules to fail and shut down. When a battery ground fault causes all power modules to fail and shut down, it is difficult to determine whether the fault lies in the battery pack or within a specific power module of the UPS system.

[0005] Therefore, how to quickly identify battery grounding faults is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This application provides a power supply system and a battery grounding fault detection method to achieve rapid identification of battery grounding faults.

[0007] In a first aspect, this application provides a power supply system including at least one power module. The power module includes: a positive power supply port, a negative power supply port, a DC / DC converter circuit, a switch, and a controller. The positive power supply port is used to connect to the positive terminal of a battery pack, and the negative power supply port is used to connect to the negative terminal of the battery pack. The switch is connected between the power supply port and the input terminal of the DC / DC circuit. Specifically, the switch can be provided only between the positive power supply port and the positive input terminal of the DC / DC circuit, or only between the negative power supply port and the negative input terminal of the DC / DC circuit, or both the positive and negative power supply ports can be provided. The positive output terminal of the DC / DC circuit is used to connect to the positive bus, and the negative output terminal is used to connect to the negative bus. The power module uses its internal sampling circuit to sample the voltages at the positive power supply port, negative power supply port, the positive input terminal of the DC / DC circuit, the negative input terminal of the DC / DC circuit, the positive bus, and the negative bus, respectively, obtaining the voltages at the positive and negative power supply ports, the positive and negative input terminals of the DC / DC circuit, the positive bus, and the negative bus. Furthermore, since the switch connecting the power supply port and the input terminal of the DC / DC circuit is in the ON state when the DC / DC circuit is operating, the voltage at the positive power supply port is the same as the voltage at the positive input port of the DC / DC circuit, and the voltage at the negative power supply port is the same as the voltage at the negative input port of the DC / DC circuit. In practical implementation, either parameter can be selected for subsequent bias voltage determination.

[0008] The controller determines whether a bias voltage has occurred by analyzing the sampled voltage, thus making a preliminary judgment on the possibility of a battery grounding fault. Specifically, the controller checks whether the voltages at the positive and negative terminals of the battery pack (equivalent to the voltages at the positive and negative input terminals of a DC / DC circuit) are biased. Simultaneously, it checks whether the voltage of a single electrode on one side of the battery pack is close to the voltage of the same busbar on that side; that is, whether the voltage of the positive terminal is close to the voltage of the positive busbar, or the voltage of the negative terminal is close to the voltage of the negative busbar. This preliminary judgment helps to determine whether a battery grounding fault may be present. By judging whether the voltage of a single electrode on one side of the battery pack is close to the voltage of the same busbar on that side, a preliminary judgment can be quickly made to determine whether a bias voltage has occurred with relatively little computation, allowing for further investigation after the fault is isolated.

[0009] Specifically, when a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the positive bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute values ​​of the voltage at the positive input terminal and the negative input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute values ​​of the voltage at the positive input terminal and the voltage at the positive bus is less than a second set value (or, if the difference between the absolute values ​​of the voltage at the positive power supply port and the negative power supply port is greater than the first set value, and the difference between the absolute values ​​of the voltage at the positive power supply port and the voltage at the positive bus is less than the second set value), it indicates a possible negative grounding fault in the battery pack. Therefore, the switch connected between the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the controller control switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute values ​​of the voltages at the positive and negative power supply ports is greater than a first set value. If the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0010] Specifically, when a ground fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than a second set value (or, if the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, and the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than the second set value), it indicates a possible positive grounding fault in the battery pack. Therefore, the switch connected between the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the controller control switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value. If the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0011] This application utilizes the sampling circuits existing within each power module for voltage sampling, saving application costs without adding new detection devices. Furthermore, this application can accurately locate and isolate battery grounding faults, preventing battery grounding faults from causing the entire power supply system to shut down.

[0012] In some embodiments of this application, in order to avoid damage to the internal devices of the power module due to possible battery grounding faults or short circuit faults inside the power module, when the controller determines that the voltage of the positive and negative terminals of the battery pack, i.e., the voltage of the positive power supply port and the negative power supply port (equivalent to the voltage of the positive input terminal and the negative input terminal of the DC / DC circuit), is biased, and at the same time the voltage of a single electrode of the battery pack is close to the voltage of the same bus, the controller in the power module can first control the DC / DC circuit to stop working, that is, turn off each switch in the DC / DC circuit, and then disconnect the switch connected between the power supply port and the input terminal of the DC / DC circuit.

[0013] In other embodiments of this application, after the controller stops the DC / DC circuit from working, it can completely turn off the switching transistor in the DC / DC circuit after a set time, and then disconnect the switch to avoid damage to the device.

[0014] In other embodiments of this application, the detection of a short-circuit fault in the DC / DC circuit of the power module can also be performed. Specifically, after the switch connecting the power module to the power supply port and the input terminal of the DC / DC circuit is disconnected, the voltages of the positive input terminal, negative input terminal, positive bus, and negative bus of the DC / DC circuit are sampled. It is determined whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased, and whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus, i.e., whether the voltage at the positive input terminal is close to the voltage of the positive bus, or whether the voltage at the negative input terminal is close to the voltage of the negative bus, to determine whether a short-circuit fault has occurred in the DC / DC circuit. This provides a preliminary assessment of the possibility of a battery grounding fault. By judging whether the voltage on one side of the input terminal is close to the voltage of the same bus, a short-circuit fault in the DC / DC circuit can be quickly determined with a relatively small computational load.

[0015] Specifically, when initially determining that a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value. If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the positive bus in the DC / DC circuit. Therefore, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0016] Specifically, when initially determining that a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than a second set value. If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the negative bus in the DC / DC circuit. In this case, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0017] Specifically, when it is initially determined that the battery pack may have a grounding fault, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than a second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than a second set value, then the power module is considered to be normal. It is necessary to turn on the switch connected between the power supply port and the input terminal of the DC / DC circuit, and then restart the DC / DC circuit, that is, control the DC / DC circuit to work.

[0018] In some embodiments of this application, the power supply system generally further includes multiple battery packs, each battery pack comprising multiple battery cells. The positive terminal of each battery pack is used to connect to the positive power supply port of at least one power module, and the negative terminal of each battery pack is used to connect to the negative power supply port of at least one power module.

[0019] Secondly, this application provides a battery grounding fault detection method, including:

[0020] The sampling circuit within the power module samples the voltages at the positive power supply port, negative power supply port, the positive input terminal of the DC / DC converter, the negative input terminal of the DC / DC converter, the positive bus, and the negative bus. This yields the voltages at the positive and negative power supply ports, the positive and negative input terminals of the DC / DC converter, the positive bus, and the negative bus. Furthermore, since the switch connecting the power supply port and the DC / DC converter's input terminal is in a conducting state during DC / DC converter operation, the voltage at the positive power supply port is the same as the voltage at the positive input terminal of the DC / DC converter, and the voltage at the negative power supply port is the same as the voltage at the negative input terminal of the DC / DC converter. In practice, either parameter can be selected for subsequent bias voltage determination.

[0021] By analyzing the sampled voltages, a preliminary assessment can be made to determine if a battery grounding fault is possible. Specifically, the voltages at the positive and negative terminals of the battery pack (equivalent to the positive and negative input terminals of a DC / DC circuit) are checked for bias. Simultaneously, the voltage at one electrode of the battery pack is compared to the voltage of the same busbar on that side; specifically, the voltage at the positive terminal is close to the voltage of the positive busbar, or the voltage at the negative terminal is close to the voltage of the negative busbar. This method allows for a quick preliminary assessment of whether a bias has occurred with minimal computation, facilitating further investigation after fault isolation.

[0022] Specifically, when a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the positive bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute values ​​of the voltage at the positive input terminal and the negative input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute values ​​of the voltage at the positive input terminal and the voltage at the positive bus is less than a second set value (or, if the difference between the absolute values ​​of the voltage at the positive power supply port and the negative power supply port is greater than the first set value, and the difference between the absolute values ​​of the voltage at the positive power supply port and the voltage at the positive bus is less than the second set value), it indicates a possible negative grounding fault in the battery pack. Therefore, the switch connecting the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute values ​​of the voltages at the positive and negative power supply ports is greater than the first set value. If the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0023] Specifically, when a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than a second set value (or, if the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port in the power module is greater than the first set value, and the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than the second set value), it indicates a possible positive grounding fault in the battery pack. Therefore, the switch connected between the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value. If the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0024] This application utilizes the sampling circuits existing within each power module for voltage sampling, saving application costs without adding new detection devices. Furthermore, this application can accurately locate and isolate battery grounding faults, preventing battery grounding faults from causing the entire power supply system to shut down.

[0025] In some embodiments of this application, in order to avoid damage to the internal devices of the power module due to possible battery grounding faults or short circuit faults inside the power module, when it is determined that the voltage of the positive and negative terminals of the battery pack, i.e. the voltage of the positive power supply port and the negative power supply port (equivalent to the voltage of the positive input terminal and the negative input terminal of the DC / DC circuit), is biased, and at the same time the voltage of a single electrode of the battery pack is close to the voltage of the same bus, the DC / DC circuit can be controlled to stop working first, that is, the switching transistors in the DC / DC circuit are turned off, and then the switch connected between the power supply port and the input terminal of the DC / DC circuit is disconnected.

[0026] In other embodiments of this application, after the DC / DC circuit stops working, the switching transistor in the DC / DC circuit can be completely turned off after a set time, and then the switch can be disconnected to avoid damage to the device.

[0027] In other embodiments of this application, the detection of a short-circuit fault in the DC / DC circuit of the power module can also be performed. Specifically, after the switch connecting the power module to the power supply port and the input terminal of the DC / DC circuit is opened, the voltage of the positive input terminal, the voltage of the negative input terminal, the voltage of the positive bus, and the voltage of the negative bus of the DC / DC circuit are sampled. It is determined whether the voltages of the positive and negative input terminals of the DC / DC circuit are biased, and whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus, i.e., whether the voltage of the positive input terminal is close to the voltage of the positive bus, or whether the voltage of the negative input terminal is close to the voltage of the negative bus, thereby determining whether a short-circuit fault has occurred in the DC / DC circuit.

[0028] Specifically, when initially determining that a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value. If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the positive bus in the DC / DC circuit. Therefore, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0029] Specifically, when initially determining that a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than a second set value. If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the negative bus in the DC / DC circuit. In this case, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0030] Specifically, when it is initially determined that the battery pack may have a grounding fault, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than a second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than a second set value, then the power module is considered to be normal. It is necessary to turn on the switch connected between the power supply port and the input terminal of the DC / DC circuit, and then restart the DC / DC circuit, that is, control the DC / DC circuit to work. Attached Figure Description

[0031] Figure 1 is a schematic diagram of the fault propagation loop when a battery grounding fault occurs;

[0032] Figure 2 is a schematic diagram of the structure of a UPS system provided in the embodiment of this application;

[0033] Figure 3 is a circuit diagram of a power supply system provided in an embodiment of this application when a battery grounding fault occurs;

[0034] Figure 4 is another circuit diagram of the power supply system provided in the embodiment of this application when a battery grounding fault occurs;

[0035] Figure 5 is a circuit diagram of the power supply system provided in the embodiment of this application when a short circuit fault occurs in the DC / DC circuit;

[0036] Figure 6 is another circuit diagram of the power supply system provided in the embodiment of this application when a short circuit fault occurs in the DC / DC circuit;

[0037] Figure 7 is a schematic diagram of voltage sampling in the DC / DC circuit of the power supply system provided in the embodiment of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, a further detailed description of this application will be provided below in conjunction with the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction as described in this application are illustrative based on the accompanying drawings, but changes may be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.

[0039] It should be noted that specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below. The following descriptions are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0040] To facilitate understanding of the embodiments of this application, the relevant technologies involved in the embodiments of this application will be introduced first below.

[0041] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” and “the” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of this application, “at least one” means one, two, or more.

[0042] References to "one embodiment" and similar terms used in this specification mean that one or more embodiments of this application include a particular feature, structure, or characteristic described in connection with that embodiment. Therefore, phrases such as "in one embodiment," "in some embodiments," and "in other embodiments" appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized.

[0043] Referring to Figure 1, when a battery pack (BAT) connected to a power supply system such as an uninterruptible power supply (UPS) experiences a ground fault, and the neutral (N) wire and grounding (PE) wire of the battery pack (BAT) share a cable or are directly connected together (i.e., the battery pack does not have a separate N wire lead-out), for example, as shown in Figure 1, if the negative terminal (BAT-) of the battery pack is short-circuited with the grounding wire (PE), since the total voltage of the battery pack remains unchanged, the voltage of the positive terminal (BAT+) of the UPS system's battery pack will be raised. The energy from the battery pack, as shown by the fault propagation loop indicated by the arrow in Figure 1, will directly flow into the positive DC bus of all power modules connected to this battery pack, causing the positive bus voltage (Vbus+) to rise. Conversely, if the positive terminal (BAT+) of the battery pack is short-circuited with the grounding wire (PE), since the total voltage of the battery pack remains unchanged, the voltage of the negative terminal (BAT-) of the UPS system's battery pack will be pulled down. The energy from the battery pack will directly flow into the negative DC bus of all power modules connected to this battery pack, causing the negative bus voltage (Vbus-) to drop. The voltage bias between the positive and negative buses will cause all power modules to fail and shut down. When a battery grounding fault causes all power modules to fail and shut down, it is difficult to determine whether the fault lies in the battery pack or in a specific power module within the UPS system.

[0044] Currently, when a UPS system shuts down due to a failure of all power modules, an external battery fault detector is used to check the leakage current of the battery pack to determine if a battery grounding fault has occurred. Using an external battery fault detector for grounding fault detection increases equipment costs, and the detector requires an external 220V auxiliary power source to operate. Regardless of whether the auxiliary power source is drawn from the UPS system's input or output side, there is a risk that the detection may fail due to insufficient power.

[0045] Based on this, the power supply system and battery grounding fault detection method provided in this application utilize the sampling circuit existing inside the power module of the power supply system for sampling. Without adding new detection devices and saving application costs, it can quickly identify battery grounding faults. Then, it disconnects the switches connected between the battery pack and each DC-DC converter circuit to isolate the battery pack with grounding faults and ensure the stability of the power supply system.

[0046] The power supply system provided in this application is applicable to various power products where the battery pack is not connected to an external neutral line, including but not limited to UPS systems, photovoltaic systems, power systems, charging piles, and other application scenarios where battery packs are connected. The following description uses a UPS system as an example of the power supply system.

[0047] Referring to Figure 2, the power supply system provided in this application specifically includes at least one power module. Taking a UPS system as an example, a UPS system generally includes multiple power modules with the same circuit topology. Each power module includes a power supply port A for connecting to a battery pack BAT. In this application, the power supply system generally also includes at least one battery pack BAT, which includes multiple battery cells. The positive terminal of one battery pack can be connected to the positive power supply port of at least one power module, and the negative terminal of one battery pack can be connected to the negative power supply port of at least one power module. In other words, the power supply ports of multiple power modules can be connected to the same battery pack. For example, a UPS includes 16 power modules, and the power supply ports of the 16 power modules are respectively connected to the same battery pack. Alternatively, multiple power modules can also be grouped, with the power supply ports of the power modules in each group connected to the same battery pack. For example, a UPS system includes 32 power modules, where the power supply ports of 16 power modules are respectively connected to one battery pack, and the power supply ports of the other 16 power modules are respectively connected to another battery pack.

[0048] Referring to Figure 2, each power module also includes a DC / DC converter circuit. The input terminal 'a' of the DC / DC converter is connected to the power supply port, and the output terminal 'b' is used to connect to the bus. In the UPS system, each power module also includes an AC / DC rectifier circuit and a DC / AC inverter circuit. The AC / DC rectifier circuit is connected between the power grid and the bus, and it converts the AC input voltage from the power grid into a DC output voltage to the bus. The DC / AC inverter circuit is connected between the bus and the load, and it converts the DC voltage from the bus into an AC output voltage to power the load.

[0049] Referring to Figure 3, the power supply ports of each power module specifically include a positive power supply port A+ and a negative power supply port A-. The input terminals of the DC / DC circuit specifically include a positive input terminal a+ and a negative input terminal a-. The output terminals of the DC / DC circuit specifically include a positive output terminal and a negative output terminal. The positive power supply port A+ is used to connect to the positive terminal BAT+ of the battery pack, and the negative power supply port A- is used to connect to the negative terminal BAT- of the battery pack. The positive output terminal of the DC / DC circuit is used to connect to the positive bus BUS+, and the negative output terminal of the DC / DC circuit is used to connect to the negative bus BUS-. A switch is typically installed between the power supply port and the input terminal of the DC / DC circuit. Specifically, switch K1 can be installed only between the positive power supply port A+ and the positive input terminal a+ of the DC / DC circuit, or switch K2 can be installed only between the negative power supply port A- and the negative input terminal a- of the DC / DC circuit. Alternatively, switch K1 can be installed between the positive power supply port A+ and the positive input terminal a+ of the DC / DC circuit, and switch K2 can be installed between the negative power supply port A- and the negative input terminal a- of the DC / DC circuit. No limitation is made here. When the controller in the power module turns on switch K1 (K2), the DC / DC circuit can provide the electrical energy from the battery pack connected to the power supply port to the bus via voltage conversion, or the DC / DC circuit can charge the electrical energy stored on the bus to the battery pack connected to the power supply port.

[0050] In this application, the DC / DC circuit can be applied to various circuit topologies. The DC-to-DC circuit may only have the function of charging the battery pack or only have the function of discharging the battery pack, or the DC / DC circuit may also have the function of charging and discharging the battery pack simultaneously.

[0051] Referring to Figure 3, in some embodiments of this application, the DC / DC circuit may specifically include: a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a second inductor L2, a first switch Q1, a second switch Q2, and a third switch Q3. The first switch Q1, the second switch Q2, and the third switch Q3 are connected in series to form a first bridge arm, with both ends connected to the positive bus BUS+ and the negative bus BUS-, respectively. The second capacitor C2 and the third capacitor C3 are connected in series to form a second bridge arm, which is connected in parallel with the first bridge arm, and its midpoint is connected to the neutral line N. A first switch K1 is used to connect to the positive terminal BAT+ of the battery pack, and a first inductor L1 is connected between the first switch K1 and the connection point of the first switch Q1 and the second switch Q2. A second switch K2 is used to connect to the negative terminal BAT- of the battery pack, and a second inductor L2 is connected between the second switch K2 and the connection point of the second switch Q2 and the third switch Q3. A first capacitor C1 is connected between the first inductor L1 and the second inductor L2. In some other embodiments of this application, a diode can be used to replace the second transistor Q2, in which case the DC / DC circuit can only perform the charging function.

[0052] Referring to Figure 4, in some embodiments of this application, the DC / DC circuit may specifically include: a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a second inductor L2, a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are connected in series to form a first bridge arm, with both ends connected to the positive bus BUS+ and the negative bus BUS-, respectively. The second capacitor C2 and the third capacitor C3 are connected in series to form a second bridge arm, which is connected in parallel with the first bridge arm. The midpoint of the second bridge arm and the connection point of the second switch Q2 and the third switch Q3 are connected to the neutral line N. A first switch K1 is used to connect to the positive terminal BAT+ of the battery pack, and a first inductor L1 is connected between the first switch K1 and the connection point of the first switch Q1 and the second switch Q2. The second switch K2 is used to connect to the negative terminal BAT- of the battery pack. The second inductor L2 is connected between the second switch K2 and the connection point of the third switch Q3 and the fourth switch Q4. The first capacitor C1 is connected between the first inductor L1 and the second inductor L2.

[0053] In this application, the switching transistor included in the DC / DC circuit can be a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), or a gallium nitride (GaN) high electron mobility transistor (HEMT), etc.

[0054] When a ground fault occurs in the battery pack, and the battery pack does not have a neutral line N, for example, as shown in Figures 3 and 4, the negative terminal BAT- of the battery pack is short-circuited with the grounding line PE. Since the total voltage of the battery pack remains unchanged, the voltage of the positive terminal BAT+ of the battery pack will be raised. The energy of the battery pack will be directly injected into the positive bus of all power modules connected to the battery pack, causing the positive bus voltage Vbus+ to be raised. This results in a voltage bias between the positive and negative bus, which will cause all power modules to fail and shut down.

[0055] Referring to Figure 7, based on this, in this application, each power module uses the sampling circuit inside the module to sample the voltages of the positive power supply port A+, the negative power supply port A-, the positive input terminal a+ of the DC / DC circuit, the negative input terminal a- of the DC / DC circuit, the positive bus BUS+, and the negative bus BUS-, respectively, to obtain the voltage of the battery pack positive terminal to the N line, i.e., the voltage of the positive power supply port Vbat+, the voltage of the battery pack negative terminal to the N line, i.e., the voltage of the negative power supply port Vbat-, the voltage of the capacitor positive terminal to the N line, i.e., the voltage of the DC / DC circuit positive input terminal Vc+, the voltage of the capacitor negative terminal to the N line, i.e., the voltage of the DC / DC circuit negative input terminal Vc-, the voltage of the DC bus positive terminal to the N line, i.e., the voltage of the positive bus Vbus+, and the voltage of the DC bus negative terminal to the N line, i.e., the voltage of the negative bus Vbus-. Furthermore, since the switch K1 (K2) connecting the power supply port and the input terminal of the DC / DC circuit is in the on state when the DC / DC circuit is working, the voltage of the positive power supply port is the same as the voltage of the positive input port of the DC / DC circuit, and the voltage of the negative power supply port is the same as the voltage of the negative input port of the DC / DC circuit. In specific implementation, either parameter can be selected for subsequent bias voltage determination.

[0056] In this application, each power module determines whether a bias voltage has occurred based on the sampled voltage, thus making a preliminary judgment on whether a battery grounding fault may be occurring. Specifically, it determines whether the voltages at the positive and negative terminals of the battery pack (i.e., the voltages at the positive and negative power supply ports, equivalent to the voltages at the positive and negative input terminals of a DC / DC circuit) are biased. Simultaneously, it checks whether the voltage of a single electrode of the battery pack is close to the voltage of the same busbar on that side; that is, whether the voltage of the positive terminal is close to the voltage of the positive busbar, or the voltage of the negative terminal is close to the voltage of the negative busbar. This preliminary judgment helps to determine whether a battery grounding fault may be occurring. By judging whether the voltage of a single electrode of the battery pack is close to the voltage of the same busbar on that side, a preliminary judgment on whether a bias voltage has occurred can be quickly made with a relatively small amount of computation, allowing for further investigation after the fault is isolated.

[0057] Specifically, when a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: Determine whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than a first set value; or, determine whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, i.e., whether |Vbat+|-|Vbat-|>△V1 or |Vc+|-|Vc-|>△V1. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value; or, determine whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the positive bus is less than the second set value, i.e., whether |Vc+|-|Vbus+|<△V2 or |Vbat+|-|Vbus+|<△V2. Both the first set value △V1 and the second set value △V2 are positive numbers. The range of the first set value △V1 and the second set value △V2 can be the same, for example, both between 0-60V. Furthermore, the first set value △V1 must be greater than the second set value △V2. When it is determined that |Vc+|-|Vc-|>△V1 (or |Vbat+|-|Vbat-|>△V1) and |Vc+|-|Vbus+|<△V2 (or |Vbat+|-|Vbus+|<△V2) are true, it indicates that there may be a negative ground fault in the battery pack. Therefore, it is necessary to turn off the switch K1 (K2) connected between the power supply port and the input terminal of the DC / DC circuit for further investigation. After switch K1 (K2) is opened, the voltages of the positive and negative terminals of the battery pack, i.e., the voltages of the positive and negative power supply ports, are sampled to determine whether the voltages of the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute values ​​of the voltages at the positive and negative power supply ports is greater than a first set value, i.e., whether |Vbat+|-|Vbat-|>△V1 is satisfied. If |Vbat+|-|Vbat-|>△V1 is true, it indicates that a ground fault has occurred at the negative terminal of the battery pack. A battery ground fault alarm is then generated and reported, and the switch remains open.

[0058] Specifically, when a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: Determine whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value; or, determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, i.e., whether |Vbat-|-|Vbat+|>△V1 or |Vc-|-|Vc+|>△V1. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than a second set value; or, determine whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than the second set value, i.e., whether |Vc-|-|Vbus-|<△V2 or |Vbat-|-|Vbus-|<△V2. Both the first set value △V1 and the second set value △V2 are positive numbers. The range of the first set value △V1 and the second set value △V2 can be the same, for example, both between 0-60V. Furthermore, the first set value △V1 must be greater than the second set value △V2. When it is determined that |Vc-|-|Vc+|>△V1 (or |Vbat-|-|Vbat+|>△V1) and |Vc-|-|Vbus-|<△V2 (or |Vbat-|-|Vbus-|<△V2) are true, it indicates that there may be a positive grounding fault in the battery pack. Therefore, it is necessary to turn off the switch K1 (K2) connected between the power supply port and the input terminal of the DC / DC circuit for further investigation. After switch K1 (K2) is opened, the voltages of the positive and negative terminals of the battery pack, i.e., the voltages of the positive and negative power supply ports, are sampled to determine whether the voltages of the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value, i.e., whether |Vbat-|-|Vbat+|>△V1 is satisfied. If |Vbat-|-|Vbat+|>△V1 is true, it indicates that a ground fault has occurred at the positive terminal of the battery pack. A battery ground fault alarm is then generated and reported, and the switch remains open.

[0059] This application utilizes the sampling circuits existing within each power module for voltage sampling, saving application costs without adding new detection devices. Furthermore, this application can accurately locate and isolate battery grounding faults, preventing battery grounding faults from causing the entire power supply system to shut down.

[0060] In some embodiments of this application, in order to avoid damage to the internal devices of the power module due to possible battery grounding faults or short circuit faults inside the power module, when it is determined that the voltage of the positive and negative terminals of the battery pack, i.e., the voltage of the positive power supply port and the negative power supply port (equivalent to the voltage of the positive input terminal and the negative input terminal of the DC / DC circuit), is biased, and at the same time the voltage of a single electrode of the battery pack is close to the voltage of the same bus, the controller in the power module can first control the DC / DC circuit to stop working, that is, turn off each switch in the DC / DC circuit, and then disconnect the switch K1 (K2) connected between the power supply port and the input terminal of the DC / DC circuit.

[0061] In other embodiments of this application, after the controller stops the DC / DC circuit from working, it can completely turn off the switching transistor in the DC / DC circuit after a set time △T1, and then disconnect the switch K1 (K2) to avoid damage to the device.

[0062] In this application, if the power module initially determines that a battery grounding fault may occur, it can also send a command to other power modules, as shown by the dotted line in Figure 2, via the inter-module communication protocol to instruct them to stop working and turn off their switches. This is to prevent other power modules from shutting down due to voltage bias on the positive and negative buses. Furthermore, the power module may also receive commands from other power modules instructing it to stop working and turn off its switches. Specifically, the DC / DC circuit and the AC / DC converter transmit commands via SPI communication, and the AC / DC converter and the central controller ECM transmit commands via CAN communication.

[0063] Referring to Figures 5 and 6, in some other embodiments of this application, the detection of a short-circuit fault in the DC / DC circuit of the power module can also be performed. Specifically, after the switch K1 (K2) connecting the power module to the power supply port and the input terminal of the DC / DC circuit is opened, the voltage Vc+ at the positive input terminal, the voltage Vc- at the negative input terminal, the voltage Vbus+ at the positive bus, and the voltage Vbus- at the negative bus of the DC / DC circuit are sampled. It is determined whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased, and whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus, i.e., whether the voltage at the positive input terminal is close to the voltage of the positive bus, or whether the voltage at the negative input terminal is close to the voltage of the negative bus, thereby determining whether a short-circuit fault has occurred in the DC / DC circuit.

[0064] Specifically, when initially determining that a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute values ​​of the voltages at the positive and negative input terminals of the DC / DC circuit is greater than a first set value, i.e., whether |Vc+|-|Vc-|>△V1. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage of the positive bus is less than a second set value, i.e., whether |Vc+|-|Vbus+|<△V2. If |Vc+|-|Vc-|>△V1 and |Vc+|-|Vbus+|<△V2 is true, it indicates that a short circuit fault has occurred in the switching transistor connected to the positive bus in the DC / DC circuit. In this case, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0065] Specifically, when initially determining that a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal is greater than a first set value, i.e., whether |Vc-|-|Vc+|>△V1. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage of the negative bus is less than a second set value, i.e., whether |Vc-|-|Vbus-|<△V2. If |Vc-|-|Vc+|>△V1 and |Vc-|-|Vbus-|<△V2 is true, it indicates that a short circuit fault has occurred in the switching transistor connected to the negative bus in the DC / DC circuit. In this case, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0066] Specifically, when initially determining that a grounding fault may occur in the battery pack, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than a second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than the second set value (i.e., |Vc+|-|Vc-|<△V2 and |Vc-|-|Vc+|<△V2 is true), then the power module is considered normal. The switch K1 (K2) connected between the power supply port and the input terminal of the DC / DC circuit needs to be turned on, and the DC / DC circuit needs to be restarted, i.e., the DC / DC circuit should be controlled to operate. For example, if a short circuit fault occurs in the first switch Q1 of power module 1 in Figures 5 and 6, power module 1 will maintain the switch open for isolation based on the above determination, preventing the short circuit fault in power module 1 from spreading to power module 2. Power module 2 will turn on the switch and restart operation based on the above determination.

[0067] Based on the same inventive concept, this application also provides a battery grounding fault detection method, including:

[0068] The sampling circuit within the power module samples the voltages at the positive power supply port, negative power supply port, the positive input terminal of the DC / DC circuit, the negative input terminal of the DC / DC circuit, the positive bus, and the negative bus, respectively, yielding the voltages at these terminals. Furthermore, since the switch connecting the power supply port and the DC / DC circuit's input terminal is in the ON state during DC / DC circuit operation, the voltage at the positive power supply port is the same as the voltage at the positive input terminal of the DC / DC circuit, and the voltage at the negative power supply port is the same as the voltage at the negative input terminal of the DC / DC circuit. In practical implementation, either parameter can be selected for subsequent bias voltage determination.

[0069] By analyzing the sampled voltages, a preliminary assessment can be made to determine if a battery grounding fault is possible. Specifically, the voltages at the positive and negative terminals of the battery pack (equivalent to the positive and negative input terminals of a DC / DC circuit) are checked for bias. Simultaneously, the voltage at one end of the battery pack electrode is compared to the voltage of the same busbar; specifically, the voltage at the positive terminal is close to the voltage of the positive busbar, or the voltage at the negative terminal is close to the voltage of the negative busbar. This method allows for a quick preliminary assessment of whether a battery grounding fault has occurred with minimal computational effort. After isolating the fault, further investigation can be conducted.

[0070] Specifically, when a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the positive bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute values ​​of the voltage at the positive input terminal and the negative input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute values ​​of the voltage at the positive input terminal and the voltage at the positive bus is less than a second set value (or, if the difference between the absolute values ​​of the voltage at the positive power supply port and the negative power supply port is greater than the first set value, and the difference between the absolute values ​​of the voltage at the positive power supply port and the voltage at the positive bus is less than the second set value), it indicates a possible negative grounding fault in the battery pack. Therefore, the switch connecting the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute values ​​of the voltages at the positive and negative power supply ports is greater than the first set value. If the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0071] Specifically, when a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltages of the positive and negative terminals of the battery pack are biased is as follows: It is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value; or, it is determined whether the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value. Correspondingly, the method for determining whether the voltage of a single electrode of the battery pack is close to the voltage of the same bus is as follows: It is determined whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than a second set value; or, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than a second set value. Both the first and second set values ​​are positive numbers, and the first set value is greater than the second set value. If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than a second set value (or, if the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port in the power module is greater than the first set value, and the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the negative bus is less than the second set value), it indicates a possible positive grounding fault in the battery pack. Therefore, the switch connected between the power supply port and the input terminal of the DC / DC circuit needs to be turned off for further troubleshooting. After the switch is turned off, the voltages at the positive and negative terminals of the battery pack, i.e., the voltages at the positive and negative power supply ports, are sampled to determine whether the voltages at the positive and negative terminals of the battery pack are biased. Specifically, it is determined whether the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than a first set value. If the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, it indicates that a grounding fault has occurred in the battery pack. In this case, a battery grounding fault alarm is generated and reported, and the switch is kept open.

[0072] This application utilizes the sampling circuits existing within each power module for voltage sampling, saving application costs without adding new detection devices. Furthermore, this application can accurately locate and isolate battery grounding faults, preventing battery grounding faults from causing the entire power supply system to shut down.

[0073] In some embodiments of this application, in order to avoid damage to the internal devices of the power module due to possible battery grounding faults or short circuit faults inside the power module, when it is determined that the voltage of the positive and negative terminals of the battery pack, i.e. the voltage of the positive power supply port and the negative power supply port (equivalent to the voltage of the positive input terminal and the negative input terminal of the DC / DC circuit), is biased, and at the same time the voltage of a single electrode of the battery pack is close to the voltage of the same bus, the DC / DC circuit can be controlled to stop working first, that is, the switching transistors in the DC / DC circuit are turned off, and then the switch connected between the power supply port and the input terminal of the DC / DC circuit is disconnected.

[0074] In other embodiments of this application, after the DC / DC circuit stops working, the switching transistor in the DC / DC circuit can be completely turned off after a set time, and then the switch can be disconnected to avoid damage to the device.

[0075] In other embodiments of this application, the detection of a short-circuit fault in the DC / DC circuit of the power module can also be performed. Specifically, after the switch connecting the power module to the power supply port and the input terminal of the DC / DC circuit is opened, the voltage of the positive input terminal, the voltage of the negative input terminal, the voltage of the positive bus, and the voltage of the negative bus of the DC / DC circuit are sampled. It is determined whether the voltages of the positive and negative input terminals of the DC / DC circuit are biased, and whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus, i.e., whether the voltage of the positive input terminal is close to the voltage of the positive bus, or whether the voltage of the negative input terminal is close to the voltage of the negative bus, thereby determining whether a short-circuit fault has occurred in the DC / DC circuit.

[0076] Specifically, when initially determining that a ground fault may occur at the negative terminal of the battery pack, the method for determining whether the voltages at the positive and negative input terminals of the DC / DC circuit are biased is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: Determine whether the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than a second set value. If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the positive bus in the DC / DC circuit. Therefore, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0077] Specifically, when initially determining that a grounding fault may occur at the positive terminal of the battery pack, the method for determining whether the voltage at the positive input terminal of the DC / DC circuit is biased is as follows: determine whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the positive input terminal is greater than a first set value. Correspondingly, the method for determining whether the voltage on one side of the input terminal of the DC / DC circuit is close to the voltage of the same bus is as follows: determine whether the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than a second set value. If the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the positive input terminal is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus is less than the second set value, it indicates that a short circuit fault has occurred in the switching transistor connected to the negative bus in the DC / DC circuit. Therefore, a DC / DC circuit fault alarm is generated and reported, and the switch remains open.

[0078] Specifically, when it is initially determined that the battery pack may have a grounding fault, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than a second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than a second set value, then the power module is considered to be normal. It is necessary to turn on the switch connected between the power supply port and the input terminal of the DC / DC circuit, and then restart the DC / DC circuit, that is, control the DC / DC circuit to work.

[0079] The power supply system and battery grounding fault detection method provided in this application utilize the sampling circuits existing within each power module for voltage sampling, saving application costs without adding new detection devices. Furthermore, this application can accurately locate and isolate battery grounding faults, preventing battery grounding faults from causing the entire power supply system to shut down. In addition, this application can also accurately locate and isolate short-circuit faults in the DC / DC circuits within each power module, preventing a short-circuit fault in a single power module from spreading to the entire power supply system and causing shutdown.

[0080] 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 the claims.

Claims

1. A power supply system, characterized in that, include: At least one power module, the power module comprising: a positive power supply port, a negative power supply port, a DC-DC converter circuit, a switch, and a controller; The positive power supply port is used to connect to the positive terminal of the battery pack, and the negative power supply port is used to connect to the negative terminal of the battery pack. The positive output terminal of the DC / DC circuit is used to connect to the positive bus, and the negative output terminal of the DC / DC circuit is used to connect to the negative bus. The switch is connected between the positive power supply port and the positive input terminal of the DC / DC circuit, or the switch is connected between the negative power supply port and the negative input terminal of the DC / DC circuit. The controller is used for: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than a first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus of the DC / DC circuit is less than a second set value, the switch is turned off; both the first set value and the second set value are positive numbers, and the first set value is greater than the second set value. After the switch is turned off, if the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than the first set value, a battery grounding fault is reported; or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, then disconnect the switch. After the switch is turned off, if the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, the battery grounding fault is reported.

2. The power supply system as described in claim 1, characterized in that, The controller is also used for: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than the second set value, the DC / DC circuit is controlled to stop working before the switch is turned off. or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, the DC / DC circuit is controlled to stop working before the switch is turned off.

3. The power supply system as described in claim 2, characterized in that, The controller is also used for: After the DC / DC circuit stops working, the switch is turned off after a set time.

4. The power supply system as described in any one of claims 1-3, characterized in that, The controller is also used for: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, after the switch is turned off, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, a fault in the DC / DC circuit shall be reported. or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, after the switch is turned off, if the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, a fault in the DC / DC circuit shall be reported.

5. The power supply system as described in claim 4, characterized in that, The controller is also used for: After the switch is turned off, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than the second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than the second set value, the switch is turned on and the DC / DC circuit is controlled to work.

6. The power supply system according to any one of claims 1-5, characterized in that, The power supply system includes multiple battery packs, each battery pack including multiple battery cells. The positive terminal of each battery pack is used to connect to the positive power supply port of the at least one power module, and the negative terminal of each battery pack is used to connect to the negative power supply port of the at least one power module.

7. A method for detecting battery grounding faults, characterized in that, include: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit in the power module is greater than a first set value, and the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus connected to the positive output terminal of the DC / DC circuit is less than a second set value, the connection is disconnected from the switch. The switch is connected between the positive power supply port and the positive input terminal of the DC / DC circuit, or the switch is connected between the negative power supply port and the negative input terminal of the DC / DC circuit. The positive power supply port is used to connect to the positive terminal of the battery pack, and the negative power supply port is used to connect to the negative terminal of the battery pack. Both the first set value and the second set value are positive numbers, and the first set value is greater than the second set value. After the switch is turned off, if the difference between the absolute value of the voltage at the positive power supply port and the absolute value of the voltage at the negative power supply port is greater than the first set value, a battery grounding fault is reported. or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal of the DC / DC circuit and the absolute value of the voltage at the negative bus connected to the negative output terminal of the DC / DC circuit is less than the second set value, then disconnect the switch. After the switch is turned off, if the difference between the absolute value of the voltage at the negative power supply port and the absolute value of the voltage at the positive power supply port is greater than the first set value, a battery grounding fault is reported.

8. The battery grounding fault detection method as described in claim 7, characterized in that, Also includes: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal of the DC / DC circuit and the absolute value of the voltage at the positive bus is less than the second set value, the DC / DC circuit is controlled to stop working before the switch is turned off. or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, the DC / DC circuit is controlled to stop working before the switch is turned off.

9. The battery grounding fault detection method as described in claim 8, characterized in that, Also includes: After the DC / DC circuit stops working, the switch is turned off after a set time.

10. The battery grounding fault detection method according to any one of claims 7-9, characterized in that, Also includes: If the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, after the switch is turned off, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the positive bus is less than the second set value, a fault in the DC / DC circuit shall be reported. or, If the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, after the switch is turned off, if the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is greater than the first set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the negative bus is less than the second set value, a fault in the DC / DC circuit shall be reported.

11. The battery grounding fault detection method as described in claim 10, characterized in that, Also includes: After the switch is turned off, if the difference between the absolute value of the voltage at the positive input terminal and the absolute value of the voltage at the negative input terminal of the DC / DC circuit is less than the second set value, and the difference between the absolute value of the voltage at the negative input terminal and the absolute value of the voltage at the positive input terminal of the DC / DC circuit is less than the second set value, the switch is turned on and the DC / DC circuit is controlled to work.

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