Fault detection method and device for uninterruptible power supply, and controller

Abstract

The invention provides a fault detection method and device for an uninterruptible power supply, and a controller. The second end of a commercial power switching device in the uninterruptible power supply is electrically connected with a corresponding battery switching device. The controller compares the second end voltage value of the commercial power switching device with the voltage value of the associated battery positive electrode access end / battery negative electrode access end before the commercial power switching device is closed, and when the absolute value of the difference value of the two voltages is smaller than or equal to a first preset voltage difference, the commercial power switching device is switched on. According to the technical scheme of the invention, the method determines that the original larger absolute value of the voltage difference value is reduced due to the fault of the battery switching device, so as to determine the faulted battery switching device and maintain or replace the device, thereby preventing the uninterruptible power supply from being damaged when the commercial power switching device is switched on, and enabling the uninterruptible power supply to be damaged because the voltage value of the battery access end is provided by an external battery or a charger capacitor. Therefore, no matter whether the external battery is connected to the uninterruptible power supply or not, the two battery connecting ends can always keep at proper voltage values, so that the smooth execution of the detection is ensured.

Description

Technical Field

[0001] This application relates to the field of uninterruptible power supplies, and particularly to a fault detection method, device and controller for an uninterruptible power supply. Background Art

[0002] An uninterruptible power supply (UPS) is a device that provides stable electrical energy for subsequent devices in a data center. The UPS includes a battery pack, a rectifier-discharge multiplexing device, an inverter device and a switching device. The switching device is electrically connected to the battery pack and the rectifier-discharge multiplexing device, and is used to supply electrical energy to the load through the rectifier-discharge multiplexing and inverter devices when the UPS operates in the battery mode, so as to improve the device utilization rate.

[0003] The switching device generally includes a plurality of battery switch devices. The plurality of battery switch devices are connected in series between the input end of the rectifier-discharge multiplexing device and the terminal of the battery. When any one of the battery switch devices is short-circuited and the mains switch device, which is electrically connected to the short-circuited battery switch device and is arranged between the input end of the rectifier-discharge multiplexing device and the mains power supply, is turned on, a short-circuit loop will be formed between the battery and the mains power supply. This short-circuit loop passes through the bus capacitor, and the short-circuit voltage generated by the superposition of the battery voltage and the mains voltage far exceeds the rated value of the bus capacitor, which will cause the bus capacitor to fail, resulting in power loss of the subsequent devices of the UPS and reducing the reliability of the UPS. Summary of the Invention

[0004] This application provides a fault detection method, device and controller for an uninterruptible power supply to solve the technical problem that the operation of the uninterruptible power supply is unstable due to the failure of the switching device.

[0005] In a first aspect, this application provides a fault detection method for an uninterruptible power supply. The method is applied to an uninterruptible power supply, which includes a battery switch device, a mains switch device, and a charger capacitor. The input end of the uninterruptible power supply, the mains switch device, and the first end of the battery switch device are sequentially connected in series. The second end of the battery switch device is electrically connected to the battery positive terminal access end or the battery negative terminal access end of the uninterruptible power supply. The battery positive terminal access end is coupled to the first end of the charger capacitor, and the battery negative terminal access end is coupled to the second end of the charger capacitor;

[0006] The method includes:

[0007] Before closing the mains switch device, obtain a first voltage difference between the second end of the mains switch device and the neutral line. The second end of the mains switch device is electrically connected to the first end of the battery switch device;

[0008] When the second terminal of the battery switch device is electrically connected to the battery positive terminal access end, a second voltage difference between the battery positive terminal access end and the neutral line is obtained; the voltage value of the battery positive terminal access end is the positive voltage value of the battery connected to the battery positive terminal access end or the voltage value of the first end of the charger capacitor;

[0009] When the second terminal of the battery switch device is electrically connected to the battery negative terminal access end, a second voltage difference between the battery negative terminal access end and the neutral line is obtained; the voltage value of the battery negative terminal access end is the negative voltage value of the battery connected to the battery negative terminal access end or the voltage value of the second end of the charger capacitor;

[0010] When the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to a first preset voltage difference, it is determined that the battery switch device is faulty.

[0011] Optionally, the uninterruptible power supply further includes a pre-charge circuit and a bus capacitor, and the input end of the uninterruptible power supply, the pre-charge circuit, the bus capacitor and the neutral line are connected in series electrically;

[0012] Before obtaining the first voltage difference between the second terminal of the mains switch device and the neutral line, the method further includes:

[0013] Controlling the pre-charge circuit to conduct, so that the input end of the uninterruptible power supply pre-charges the bus capacitor.

[0014] Optionally, the uninterruptible power supply further includes a battery charging circuit, a first charging switch device and a second charging switch device. The first charging switch device is connected in series between the battery positive terminal access end and the first end of the charger capacitor, and the second charging switch device is connected in series between the battery negative terminal access end and the second end of the charger capacitor. The first end and the second end of the battery charging circuit are electrically connected to the charger capacitor, and the third end and the fourth end of the battery charging circuit are electrically connected to the bus capacitor;

[0015] Before obtaining the second voltage difference between the battery positive terminal access end and the neutral line and obtaining the second voltage difference between the battery negative terminal access end and the neutral line, the method further includes:

[0016] Obtaining the access state of the battery; the access state includes an accessed state or a non-accessed state;

[0017] When the battery is in the unconnected state and the voltage difference across the charger capacitor is less than a second preset voltage difference, control the battery charging circuit to charge the charger capacitor until the voltage difference across the charger capacitor is a third voltage difference, and after the charging is completed, turn on the first charging switch device and the second switch device;

[0018] The third voltage difference is greater than or equal to the second preset voltage difference.

[0019] Optionally, the third voltage difference is less than a third preset voltage difference, and the third preset voltage difference is determined based on the bus voltage across which the bus capacitor is connected.

[0020] Optionally, obtaining the connection state of the battery includes:

[0021] After the uninterruptible power supply is powered on, obtain the voltage difference between the positive battery connection terminal and the negative battery connection terminal;

[0022] When the voltage difference between the positive battery connection terminal and the negative battery connection terminal is less than the second preset voltage difference, determine that the battery is in the unconnected state;

[0023] When the voltage difference between the positive battery connection terminal and the negative battery connection terminal is greater than or equal to the second preset voltage difference, determine that the battery is in the connected state.

[0024] Optionally, controlling the battery charging circuit to charge the voltage difference across the charger capacitor to a third voltage difference includes:

[0025] The battery charging circuit charges the charger capacitor using the electrical energy stored in the bus capacitor.

[0026] Optionally, after obtaining the second voltage difference, the method further includes:

[0027] When the absolute value of the difference between the first voltage difference and the second voltage differences corresponding to each of the battery switch devices is greater than a first preset voltage difference, close the mains switch device of the uninterruptible power supply to control the operation of the uninterruptible power supply.

[0028] In a second aspect, the present application provides a fault detection device for an uninterruptible power supply, including:

[0029] An acquisition module, configured to obtain a first voltage difference between the second terminal of the mains switch device and the neutral line before closing the mains switch device; wherein, the mains switch device is located in an uninterruptible power supply, and the uninterruptible power supply further includes a battery switch device and a charger capacitor. The input end of the uninterruptible power supply is electrically connected to the first terminal of the mains switch device, the second terminal of the mains switch device is electrically connected to the battery switch device, the second terminal of the battery switch device is electrically connected to the battery positive terminal access end or the battery negative terminal access end of the uninterruptible power supply, the battery positive terminal access end is coupled to the first terminal of the charger capacitor, and the battery negative terminal access end is coupled to the second terminal of the charger capacitor;

[0030] The acquisition module is further configured to obtain a second voltage difference between the battery positive terminal access end and the neutral line when the second terminal of the battery switch device is electrically connected to the battery positive terminal access end; the voltage value of the battery positive terminal access end is the positive voltage value of the battery connected to the battery positive terminal access end or the voltage value of the first terminal of the charger capacitor;

[0031] The acquisition module is further configured to obtain a second voltage difference between the battery negative terminal access end and the neutral line when the second terminal of the battery switch device is electrically connected to the battery negative terminal access end; the voltage value of the battery negative terminal access end is the negative voltage value of the battery connected to the battery negative terminal access end or the voltage value of the second terminal of the charger capacitor;

[0032] A processing module, configured to determine that the battery switch device fails when the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to a first preset voltage difference.

[0033] Optionally, the processing module is further configured to control the pre-charge circuit to conduct before the acquisition module obtains the first voltage difference between the second terminal of the mains switch device and the neutral line, so as to pre-charge the bus capacitor at the input end of the uninterruptible power supply;

[0034] Wherein, the uninterruptible power supply further includes the pre-charge circuit and the bus capacitor, and the input end of the uninterruptible power supply, the pre-charge circuit, the bus capacitor and the neutral line are connected in series electrically.

[0035] In a third aspect, the present application provides a controller, including: a processor and a memory communicatively connected to the processor;

[0036] The memory stores computer-executable instructions;

[0037] The processor is configured to implement the method according to any one of the first aspect when executing the computer-executable instructions.

[0038] The present application provides a fault detection method, device and controller for an uninterruptible power supply. In an uninterruptible power supply using a rectifier-discharge multiplexing converter, a battery switch device, a mains switch device and a charger capacitor are provided. The input end of the uninterruptible power supply, the mains switch device, and the first end of the battery switch device are sequentially connected in series. The second end of the battery switch device is electrically connected to the battery positive terminal access end or the battery negative terminal access end of the uninterruptible power supply. The battery positive terminal access end is coupled to the first end of the charger capacitor, and the battery negative terminal access end is coupled to the second end of the charger capacitor. Before closing the mains switch device, a first voltage difference between the second end of the mains switch device electrically connected to the battery switch device and the neutral line is obtained. When the battery switch device is electrically connected to the battery positive terminal access end, a second voltage difference between the battery positive terminal access end and the neutral line is obtained. When the battery switch device is electrically connected to the battery negative terminal access end, a second voltage difference between the battery negative terminal access end and the neutral line is obtained. When the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to a first preset voltage difference, it is determined that the battery switch device is faulty, and timely maintenance is carried out, thereby avoiding the damage caused by the fault of the battery switch device in the uninterruptible power supply, and ensuring the stability of the operation of the uninterruptible power supply. Since the voltage value at the battery access end is provided by an external battery or a charger capacitor, regardless of whether the external battery is connected to the uninterruptible power supply, during the above detection process, the two battery access ends can always be maintained at appropriate voltage values, thereby ensuring the smooth execution of the above detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are incorporated herein and form a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0040] Figure 1 FIG. is a schematic structural diagram of an uninterruptible power supply according to an exemplary embodiment of the present application;

[0041] Figure 2A FIG. is a schematic structural diagram of an uninterruptible power supply according to another exemplary embodiment of the present application;

[0042] Figure 2B FIG. is a schematic structural diagram of an uninterruptible power supply according to another exemplary embodiment of the present application;

[0043] Figure 3 FIG. is a schematic flow chart of a fault detection method for an uninterruptible power supply according to an exemplary embodiment of the present application;

[0044] Figure 4 FIG. is a schematic flow chart of a fault detection method for an uninterruptible power supply according to another exemplary embodiment of the present application;

[0045] Figure 5Schematic flowchart of a fault detection method for an uninterruptible power supply according to another exemplary embodiment of the present application;

[0046] Figure 6 Schematic diagram of the voltage waveform at the second terminal of the mains relay corresponding to a battery relay fault according to an exemplary embodiment of the present application;

[0047] Figure 7 Schematic structural diagram of a fault detection device for an uninterruptible power supply according to an exemplary embodiment of the present application;

[0048] Figure 8 Schematic structural diagram of a controller according to an embodiment of the present application.

[0049] Through the above-mentioned drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed Description of Specific Embodiments

[0050] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0051] A data center, commonly known as a computer room, includes a computer system, a communication system, a storage system, environmental control equipment, monitoring equipment, and various security devices. Stable power supply to the data center is a prerequisite for ensuring the stable operation of the data center. Therefore, an uninterruptible power supply is generally installed in the data center, electrically connected between the mains and the electrical equipment in the data center, and used to supply power to each electrical equipment stably and continuously.

[0052] Figure 1 Schematic circuit diagram of an uninterruptible power supply according to an exemplary embodiment of the present application. As Figure 1As shown, the uninterruptible power supply includes a UPS pre-stage distribution transformer 101, a UPS rectifier and discharge multiplexing conversion circuit, and a battery 104. The UPS rectifier and discharge multiplexing conversion circuit includes: a rectifier and discharge multiplexing conversion unit 102, a battery charging circuit 103, a plurality of mains relays RLY1 to RLY6, bus capacitors C1, C2, a charger capacitor C3, charger relays RLY13, RLY14, a plurality of fuses Fuse1 to Fuse5, and a plurality of battery relays RLY7 to RLY12. Among them, the rectifier and discharge multiplexing conversion unit 102 includes two rectifier and discharge multiplexing conversion circuits 1021 and 1022.

[0053] The UPS pre-stage distribution transformer 101 includes Lu, Lv, Lw, and N lines. The three-phase power output terminals are respectively electrically connected to three fuses Fuse1 to Fuse3. Each fuse is electrically connected to the corresponding-phase input terminals of the two rectifier and discharge multiplexing conversion circuits 1021 and 1022. A corresponding mains relay is also connected in series between the fuse and the input terminal: the fuse Fuse1 provided at the U-phase output terminal is electrically connected to the mains relay RLY1 in the rectifier and discharge multiplexing conversion circuit 1021 and the mains relay RLY4 in the rectifier and discharge multiplexing conversion circuit 1022. The fuse Fuse2 corresponding to the V-phase power is electrically connected to the mains relays RLY2 and RLY5. The fuse Fuse3 corresponding to the W-phase power is electrically connected to the mains relays RLY3 and RLY6.

[0054] The bus capacitor C1 is connected across the two output terminals of the rectifier and discharge multiplexing conversion circuit 1021. The bus capacitor C2 is connected across the two output terminals of the rectifier and discharge multiplexing conversion circuit 1022. The first end of the bus capacitor C1 is connected to the bus BUS+, and the second end is connected to the neutral line N. The first end of the bus capacitor C2 is connected to the neutral line N, and the second end is connected to the bus BUS-.

[0055] The bus is electrically connected to the two input terminals of the battery charging circuit 103. One output terminal of the battery charging circuit 103 is connected in series with the charger relay RLY13 and the fuse Fuse4 and then electrically connected to the positive electrode of the battery unit 104. The other output terminal of the battery charger 103 is connected in series with the charger relay RLY14 and the fuse Fuse5 and then electrically connected to the negative electrode of the battery unit 104.

[0056] The battery charging circuit 103 includes a plurality of transistors. Each transistor is anti-parallel connected with a freewheeling diode. One output terminal thereof electrically connected to the bus BUS- is electrically connected to the positive electrode of a freewheeling diode. One input terminal thereof electrically connected to the charger relay RLY14 is electrically connected to the negative electrode of the freewheeling diode.

[0057] The fuse Fuse4 and the charger relay RLY13 are electrically connected to a point A. Point A is coupled to the second ends of the three mains relays in the rectifying and discharging multiplexing conversion circuit 1021. The first ends of the mains relays are coupled to the corresponding fuses. A battery relay is serially connected between point A and the second end of each mains relay: a battery relay RLY7 is serially connected between point A and the mains relay RLY1, a battery relay RLY8 is serially connected between point A and the mains relay RLY2, and a battery relay RLY9 is serially connected between point A and the mains relay RLY3.

[0058] The fuse Fuse5 and the charger relay RLY14 are electrically connected to a point B. Point B is coupled to the second ends of the three mains relays in the rectifying and discharging multiplexing conversion circuit 1022. The first ends of the mains relays are coupled to the corresponding fuses. A battery relay is serially connected between point B and the second end of each mains relay: a battery relay RLY10 is serially connected between point B and the mains relay RLY4, a battery relay RLY11 is serially connected between point B and the mains relay RLY5, and a battery relay RLY12 is serially connected between point B and the mains relay RLY6.

[0059] Based on the circuit connection relationship of the above uninterruptible power supply, when at least one battery relay is short-circuited, after the mains relay electrically connected to the battery relay is powered on, a short-circuit loop will be formed between the battery and the mains (for example: when the battery relay RLY7 is short-circuited, after the mains relay RLY1 is powered on, the short-circuit loop successively includes: the battery positive pole Bat+, the fuse Fuse4, the battery relay RLY7, the mains relay RLY1, the fuse Fuse1, the U-phase electricity, the neutral line N, the bus capacitor C2, the freewheeling diode anti-parallel to the transistor Q15, the inductor L8, the charger relay RLY14, the fuse Fuse5, the battery negative pole Bat-). The voltage value of this short-circuit loop will superimpose the battery voltage and the voltage of one phase of the mains. This superimposed voltage will act on the bus capacitor, far exceeding the rated value of the bus capacitor, resulting in the failure of the bus capacitor, thereby causing the power failure of the subsequent devices of the UPS and reducing the reliability of the UPS.

[0060] To solve the above problems, the present application provides a fault detection method, device, and controller for an uninterruptible power supply. The technical concept of the present application is as follows: In an uninterruptible power supply applying a rectifier-discharge multiplexing converter, there are a battery switch device, a mains switch device, and a charger capacitor. The input end of the uninterruptible power supply, the mains switch device, and the first end of the battery switch device are connected in series and electrically connected in sequence. The second end of the battery switch device is electrically connected to the battery positive terminal access end or the battery negative terminal access end of the uninterruptible power supply. The battery positive terminal access end is coupled to the first end of the charger capacitor, and the battery negative terminal access end is coupled to the second end of the charger capacitor. Before closing the mains switch device, obtain the first voltage difference between the second end of the mains switch device electrically connected to the battery switch device and the neutral line. When the battery switch device is electrically connected to the battery positive terminal access end, obtain the second voltage difference between the battery positive terminal access end and the neutral line. When the battery switch device is electrically connected to the battery negative terminal access end, obtain the second voltage difference between the battery negative terminal access end and the neutral line. When the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to the first preset voltage difference, determine that the battery switch device is faulty, and perform maintenance in a timely manner, thereby avoiding the damage caused by the fault of the battery switch device in the uninterruptible power supply and ensuring the stability of the operation of the uninterruptible power supply. Since the voltage value at the battery access end is provided by the external battery or the charger capacitor, regardless of whether the external battery is connected to the uninterruptible power supply, during the above detection process, the two battery access ends can always maintain an appropriate voltage value, thereby ensuring the smooth execution of the above detection.

[0061] The technical solution of the present application will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0062] First, the circuit structure of the uninterruptible power supply will be explained. The fault detection method for the uninterruptible power supply provided by the present application can be applied to an uninterruptible power supply applying a rectifier-discharge multiplexing converter, that is, a switch device is connected in series between the battery and the input end of the rectifier circuit in the uninterruptible power supply. Except Figure 1 for the uninterruptible power supply shown, it can also be a variant of the circuit structure shown in Figure 1 , including but not limited to: an uninterruptible power supply with multiple parallel-connected UPS rectifier-discharge multiplexing conversion circuits electrically connected between the UPS front-stage distribution transformer 101 and the battery 104; an uninterruptible power supply in which the rectifier-discharge multiplexing conversion unit 102 only includes one rectifier-discharge multiplexing conversion circuit; an uninterruptible circuit in which the Vienna topology in the rectifier-discharge multiplexing conversion unit 102 shown in Figure 1 is replaced by a BOOST circuit; the battery charging circuit 103 shown in Figure 1 is replaced by a battery charging circuit with an N line (such as Figure 2Aas shown in the figure); an uninterruptible power supply in which the switching device is replaced by other switching devices such as a contactor, a silicon controlled rectifier (SCR), an IGBT, a MOSFET, etc.; an uninterruptible power supply that sets at least one of the battery relays RLY7 to RLY9 and sets at least one of the battery relays RLY10 to RLY12 (for example: an uninterruptible power supply that only sets RLY7 and RLY10).

[0063] When the uninterruptible power supply in the rectifying and discharging multiplexing conversion unit 102 only includes one rectifying and discharging multiplexing conversion circuit, at least two battery relays are respectively electrically connected between two mains relays and the battery positive electrode BAT+ and the battery negative electrode BAT-. A circuit structure of the uninterruptible power supply is as Figure 2B shown, where the battery relay RLY7 is electrically connected between the second end of the mains relay RLY1 and the battery positive electrode BAT+, and the battery relay RLY8 is electrically connected between the second end of the mains relay RLY2 and the battery negative electrode BAT-. When any battery relay is short-circuited, it will also cause a short circuit between the battery and the distribution transformer. The short-circuit loop is similar to the aforementioned short-circuit loop and will not be elaborated here.

[0064] Figure 3 This is a schematic flowchart of a fault detection method for an uninterruptible power supply provided by this application according to an exemplary embodiment. This method is applied to an uninterruptible power supply including a rectifying and discharging multiplexing converter. This method includes:

[0065] S101. Before closing the mains switching device, obtain the first voltage difference between the second end of the mains switching device and the neutral line.

[0066] Wherein, the first end of the mains switching device is electrically connected to the distribution transformer, the second end is electrically connected to the first end of the battery switching device, and the second end of the battery switching device is electrically connected to the battery positive electrode access end / battery negative electrode access end.

[0067] The uninterruptible power supply includes a charger capacitor. The battery positive electrode access end is coupled to the positive electrode of the external battery and the first end of the charger capacitor; the battery negative electrode access end is coupled to the negative electrode of the external battery and the second end of the charger capacitor.

[0068] When an external battery is connected to the uninterruptible power supply, the positive electrode access terminal of the battery is electrically connected to the positive electrode of the external battery, and the negative electrode access terminal of the battery is electrically connected to the negative electrode of the external battery. The voltage value of the positive electrode access terminal of the battery is the same as the voltage value of the positive electrode of the external battery, and the voltage value of the negative electrode access terminal of the battery is the same as the voltage value of the negative electrode of the external battery. When the external battery is not connected to the uninterruptible power supply, the positive electrode access terminal of the battery is electrically coupled to the first end of the charger capacitor, and the negative electrode access terminal of the battery is coupled to the second end of the charger capacitor. When the circuit between the positive electrode access terminal of the battery and the first end of the charger capacitor is conductive, the voltage value of the positive electrode access terminal of the battery is determined based on the voltage value of the first end of the charger capacitor. When the circuit between the negative electrode access terminal of the battery and the second end of the charger capacitor is conductive, the voltage value of the negative electrode access terminal of the battery is determined based on the voltage value of the second end of the charger capacitor.

[0069] In some embodiments, when the circuit between the positive electrode access terminal of the battery and the first end of the charger capacitor is conductive, the voltage value of the positive electrode access terminal of the battery is the same as the voltage value of the first end of the charger capacitor. When the circuit between the negative electrode access terminal of the battery and the second end of the charger capacitor is conductive, the voltage value of the negative electrode access terminal of the battery is the same as the voltage value of the second end of the charger capacitor.

[0070] In one embodiment, the mains switch device and the battery switch device can be any one of the following: relay, contactor, SCR, IGBT, MOSFET. It can also be other switch devices, and no specific limitation is made here.

[0071] Before closing the mains switch device, the second end of the mains switch device is not connected to the distribution transformer. In this case, the voltage difference between its second end and the neutral line N is measured.

[0072] S102. When the second end of the battery switch device is electrically connected to the positive electrode access terminal of the battery, obtain the second voltage difference between the positive electrode access terminal of the battery and the neutral line.

[0073] The positive electrode access terminal of the battery is the terminal that is electrically connected to the positive electrode of the battery when the battery is connected to the uninterruptible power supply.

[0074] S103. When the second end of the battery switch device is electrically connected to the negative electrode access terminal of the battery, obtain the second voltage difference between the negative electrode access terminal of the battery and the neutral line.

[0075] The negative electrode access terminal of the battery is the terminal that is electrically connected to the negative electrode of the battery when the battery is connected to the uninterruptible power supply.

[0076] S104. When the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to the first preset voltage difference, determine that the battery switch device is faulty.

[0077] When the battery switch device is fault-free, the battery switch device is turned off. Since the circuit between the mains switch device and the bus capacitor is turned off at this time, the potential value of the second end of the mains switch device is not affected by the power supply device or the energy storage device (external battery or charger capacitor), and its voltage relative to the neutral line is not more than the preset voltage. And the absolute value of the second voltage difference obtained in step S102 or S103 is much larger than the preset voltage. When the battery switch device is fault-free, the absolute value of the difference between the first voltage difference and the second voltage difference is greater than the first preset voltage difference.

[0078] When the battery switch device has a fault, the battery switch device is short-circuited. Since the second end of the battery switch device is electrically connected to the battery positive terminal access end / battery negative terminal access end, the potential value of its first end is adjusted to the same potential value as its second end with the short circuit, that is, the absolute value of the difference between the potential value of the second end of the mains switch device and the potential value of the first end of the battery switch device is a voltage difference less than or equal to the first preset voltage difference, and the first preset voltage difference is determined by the voltage drop generated on the circuit between the two ends. Then, it can be determined that the battery switch device has a fault according to the situation that the absolute value of the difference determined by the first voltage difference measured in step S101 and the second voltage difference measured in step S102 or step S103 is less than or equal to the first preset voltage difference.

[0079] In one embodiment, when the voltage drop between the battery switch device and the mains switch device is negligible, the first preset voltage difference is 0V.

[0080] In the above technical solution, before closing the mains switch device, by comparing the voltage value of the second end of the mains switch device with the voltage value of the battery positive terminal access end / battery negative terminal access end associated with it, when the absolute value of the difference between the two voltages is less than or equal to the first preset voltage difference, it is determined that due to the fault of the battery switch device, the absolute value of the originally larger voltage difference has been reduced, so that the faulty battery switch device can be determined, and the device can be repaired or replaced to avoid the damage of the uninterruptible power supply caused by the fault of the battery switch device after closing the mains switch device subsequently. Since the voltage value of the battery access end is provided by the external battery or the charger capacitor, therefore, regardless of whether the external battery is connected to the uninterruptible power supply, in the above detection process, the two battery access ends can always be maintained at appropriate voltage values, thus ensuring the smooth execution of the above detection.

[0081] When performing fault detection on the uninterruptible power supply, there are two situations: battery connected and battery not connected.

[0082] When the battery is connected, the flow chart of the fault detection method for the uninterruptible power supply is as Figure 4 shown, and the steps include:

[0083] S201. Control the pre-charge circuit to conduct, so that the input end of the uninterruptible power supply pre-charges the bus capacitor, and determine that the battery is in the connected state.

[0084] The uninterruptible power supply further includes a pre-charge circuit and a bus capacitor. The input end of the uninterruptible power supply, the pre-charge circuit, the bus capacitor and the neutral line are connected in series electrically.

[0085] Among them, the pre-charge circuit includes a rectifier circuit, a switching device and a current-limiting resistor connected across the three-phase power of the bus and the distribution transformer, and is a circuit for charging the bus capacitor connected across the bus with a limited charging current before the mains switching device is closed.

[0086] When the mains switching device is closed, the pre-charge circuit will be disconnected.

[0087] When the battery is in the connected state, the battery positive connection end is electrically connected to the battery positive electrode, and the battery negative connection end is electrically connected to the battery negative electrode. The connection state of the battery is determined by measuring the voltage value between the battery positive connection end and the battery negative connection end. When the voltage difference between the two ends is greater than the second preset voltage difference, it is determined that the battery is connected; when the voltage difference between the two ends is less than or equal to the second preset voltage difference, it is determined that the battery is not connected.

[0088] A first charging switch device is connected in series electrically between the battery positive connection end and the first end of the charger capacitor, and a second charging switch device is connected in series electrically between the battery negative connection end and the second end of the charger capacitor. At this time, the charging switch devices electrically connected between the battery positive connection end, the battery negative connection end and the charger capacitor are turned off, and the voltage value across the charger capacitor will not affect the voltage values of the battery positive connection end and the battery negative connection end. In some embodiments, the charging switch devices include, but are not limited to: charger relays, contactors, SCRs, IGBTs, MOSFETs.

[0089] S202. Before closing the mains switching device, obtain the first voltage difference between the second end of the mains switching device and the neutral line.

[0090] When the battery switch device is electrically connected to the battery positive connection end, obtain the second voltage difference between the battery positive connection end and the neutral line.

[0091] The second voltage difference between the battery positive connection end and the neutral line is the voltage difference between the battery positive electrode and the neutral line.

[0092] S204. When the battery switch device is electrically connected to the battery negative connection end, obtain the second voltage difference between the battery negative connection end and the neutral line.

[0093] The second voltage difference between the battery negative connection end and the neutral line is the voltage difference between the battery negative electrode and the neutral line.

[0094] Among them, the order of obtaining the first voltage difference and the second voltage difference is not specifically limited. The order shown in this application is only an example of obtaining the voltage difference.

[0095] S205. Determine whether the absolute value of the difference between the first voltage difference and the second voltage difference corresponding to each battery switch device is greater than a first preset voltage difference.

[0096] If so, go to step S206; otherwise, go to step S207.

[0097] S206. Close the mains switch device of the uninterruptible power supply to control the operation of the uninterruptible power supply.

[0098] Since the absolute value of the difference between the first voltage difference and the second voltage difference corresponding to each battery switch device is greater than the first preset voltage difference, it is determined that each battery switch device has no fault, and the mains switch device of the uninterruptible power supply can be closed to control the uninterruptible power supply to continue operating.

[0099] S207. Determine the fault of the battery switch device that does not meet the conditions.

[0100] When the absolute value of the difference between the first voltage difference and the second voltage difference corresponding to at least one battery switch device is less than or equal to the first preset voltage difference, it is determined that the mains switch device will damage the bus capacitor after being powered on. Therefore, it is necessary to determine the faulty battery switch device according to the absolute value of the difference, and the battery switch device needs to be repaired or replaced. After confirming that the obstacle is cleared, the mains switch device of the uninterruptible power supply is closed again.

[0101] When the battery is not connected, the flow chart of the fault detection method of the uninterruptible power supply is as Figure 5 shown, and the steps include:

[0102] S301. Control the pre-charge circuit to conduct, so that the input end of the uninterruptible power supply pre-charges the bus capacitor, and determine that the battery is in an unconnected state.

[0103] This step is the same as S201 and will not be elaborated here.

[0104] S302. Determine whether the voltage difference across the charger capacitor is less than a second preset voltage difference.

[0105] If so, go to step S303 to charge the charger capacitor; otherwise, no charging is required, and go to step S304.

[0106] S303. Control the battery charging circuit to charge the charger capacitor until the voltage difference across the charger capacitor is a third voltage difference.

[0107] The third voltage difference is greater than or equal to the second preset voltage difference and less than the third preset voltage difference. For example, the third voltage difference is greater than or equal to 400V and less than 700V. The third preset voltage difference is determined based on the bus voltage across the bus capacitor and the battery charging circuit, where the third preset voltage difference is less than the bus voltage.

[0108] During the process of the battery charging circuit charging the charger capacitor, the first charging switch device connected in series between the first end of the charging capacitor and the battery positive terminal access is disconnected, and the second charging switch device connected in series between the second end of the charging capacitor and the battery negative terminal access is disconnected.

[0109] S304. Conduct the first charging switch device and the second charging switch device.

[0110] After the first charging switch device and the second charging switch device are conducted, the charger capacitor can provide voltage to the second end of the battery switch device instead of the external battery, so that in the case where the battery is not connected, it is still possible to determine whether there is a fault in the battery switch device through subsequent potential comparison.

[0111] S305. Before closing the mains switch device, obtain the first voltage difference between the second end of the mains switch device and the neutral line.

[0112] S306. When the second end of the battery switch device is electrically connected to the battery positive terminal access, obtain the second voltage difference between the battery positive terminal access and the neutral line.

[0113] S307. When the second end of the battery switch device is electrically connected to the battery negative terminal access, obtain the second voltage difference between the battery negative terminal access and the neutral line.

[0114] S308. Determine whether the absolute value of the difference between the first voltage difference and the second voltage differences corresponding to all battery switch devices is greater than the first preset voltage difference.

[0115] If so, go to step S310; otherwise, go to step S309.

[0116] S309. Determine that the battery switch device that does not meet the conditions is faulty.

[0117] S310. Close the mains switch device of the uninterruptible power supply to control the operation of the uninterruptible power supply.

[0118] Next, taking Figure 1 the circuit structure shown as an example, the fault detection method provided by the present application will be explained.

[0119] Before the mains relays RLY1~RLY6 in the uninterruptible power supply are closed, if it is determined that the battery is connected, the circuit between the controller and the mains is first conducted, the controller works, and the controller controls the pre-charge circuit to charge the bus capacitor. After the pre-charging is completed, the voltages URLY1, URLY2, URLY3, URLY4, URLY5, URLY6 of the second ends (right endpoints) of the mains relays RLY1, RLY2, RLY3, RLY4, RLY5, RLY6 relative to the N line are obtained through the voltage measuring device, and the voltages UBat+ and UBat- of the positive and negative poles of the battery relative to the N line are also measured.

[0120] If the absolute value of the difference between the voltage URLY1 at the rear end of the mains relay RLY1 and the N line and the positive port voltage UBat+ of the battery is less than or equal to the first preset voltage difference, and / or the absolute value of the difference between the voltage URLY2 at the rear end of the mains relay RLY2 and the N line and the positive port voltage UBat+ of the battery is less than or equal to the first preset voltage difference, and / or the absolute value of the difference between the voltage URLY3 at the rear end of the mains relay RLY3 and the N line and the positive port voltage UBat+ of the battery is less than or equal to the first preset voltage difference, and / or the absolute value of the difference between the voltage URLY4 at the rear end of the mains relay RLY4 and the N line and the negative port voltage UBat- of the battery is less than or equal to the first preset voltage difference, and / or the absolute value of the difference between the voltage URLY5 at the rear end of the mains relay RLY5 and the N line and the negative port voltage UBat- of the battery is less than or equal to the first preset voltage difference, and / or the absolute value of the difference between the voltage URLY6 at the rear end of the mains relay RLY6 and the N line and the negative port voltage UBat- of the battery is less than or equal to the first preset voltage difference, it is necessary to alarm that the battery relay is short-circuited.

[0121] More specifically, if the absolute value of the difference between the voltage URLY1 at the rear end of the mains relay RLY1 with respect to the N line and the battery positive terminal voltage UBat+ is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY7; if the absolute value of the difference between the voltage URLY2 at the rear end of the mains relay RLY2 with respect to the N line and the battery positive terminal voltage UBat+ is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY8; if the absolute value of the difference between the voltage URLY3 at the rear end of the mains relay RLY3 with respect to the N line and the battery positive terminal voltage UBat+ is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY9; if the absolute value of the difference between the voltage URLY4 at the rear end of the mains relay RLY4 with respect to the N line and the battery negative terminal voltage UBat- is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY10; if the absolute value of the difference between the voltage URLY5 at the rear end of the mains relay RLY5 with respect to the N line and the battery negative terminal voltage UBat- is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY11; if the absolute value of the difference between the voltage URLY6 at the rear end of the mains relay RLY6 with respect to the N line and the battery negative terminal voltage UBat- is less than or equal to the first preset voltage difference, an alarm is issued for a short circuit in the battery relay RLY12. An accurate alarm is more convenient for maintenance personnel to repair, and the continued closing of the mains relays RLY1, RLY2, RLY3, RLY4, RLY5, RLY6 and the activation of the rectifier are prohibited.

[0122] For easy understanding, the simulation diagram ( Figure 6 ) is used for illustration. Taking the short circuit of the battery relay RLY9 as an example, assuming the battery voltage UBat is 500V, then UBat+ = UBat- = 250V. If there is no short circuit in the battery relay, the voltage waveform of URLY3 is close to 0V. Once a short circuit occurs in the battery relay RLY9, the voltage waveform of URLY3 will become Figure 6 the waveform shown, which indicates that the voltage URLY3 at the rear end of the mains relay RLY3 with respect to the N line is the same as the battery positive terminal voltage UBat+.

[0123] When the potential values at the rear ends of the above mains relays are not the same as the corresponding battery terminal voltages, it is determined that there is no short circuit fault in the battery relay, and the mains relays RLY1, RLY2, RLY3, RLY4, RLY5, RLY6 are continuously closed, and the module operates according to the normal logic.

[0124] Before the mains relays RLY1 - RLY6 in the uninterruptible power supply are closed, it is determined that the battery is not connected. First, the loop between the controller and the mains is conducted, the controller works, and the controller controls the pre - charge loop to charge the bus capacitor.

[0125] Detect the battery voltage UBat before closing the mains relays RLY1, RLY2, RLY3, RLY4, RLY5, RLY6, that is, the voltage difference across the charger capacitor C3. When the measured voltage UBat is less than 400V (since the battery voltage adapted by the current uninterruptible power supply is between 400V and 700V, 400V is used as the differentiation point, and this battery voltage can be dynamically adjusted according to the battery voltage adapted by the system), disconnect the charger relays RLY13 and RLY14, turn on the charger topology, and charge the charger filter capacitor C3 to a voltage value within 400V - 700V, for example: 500V.

[0126] Close the charger relays RLY13 and RLY14, and continue to detect the voltages URLY1, URLY2, URLY3, URLY4, URLY5, URLY6 between the second ends of the mains relays RLY1, RLY2, RLY3, RLY4, RLY5, RLY6 and the N - line, and the voltages UBat+ and UBat- between the positive and negative poles of the battery and the N - line. The subsequent detection method is the same as the detection and judgment method when the battery is connected, and will not be elaborated here.

[0127] Figure 7 FIG. is a schematic structural diagram of a fault detection device for an uninterruptible power supply according to an embodiment of the present application. The fault detection device 400 of the uninterruptible power supply includes an acquisition module 401 and a processing module 402, where,

[0128] The acquisition module 401 is configured to obtain a first voltage difference between the second end of the mains switch device and the neutral line before closing the mains switch device; wherein, the mains switch device is located in the uninterruptible power supply, and the uninterruptible power supply further includes a battery switch device and a charger capacitor. The input end of the uninterruptible power supply is electrically connected to the first end of the mains switch device, the second end of the mains switch device is electrically connected to the battery switch device, the second end of the battery switch device is electrically connected to the battery positive - pole access end or the battery negative - pole access end of the uninterruptible power supply, the battery positive - pole access end is coupled to the first end of the charger capacitor, and the battery negative - pole access end is coupled to the second end of the charger capacitor;

[0129] The acquisition module 401 is further configured to obtain a second voltage difference between the battery positive - pole access end and the neutral line when the second end of the battery switch device is electrically connected to the battery positive - pole access end. The voltage value of the battery positive - pole access end is the positive - pole voltage value of the battery connected to the battery positive - pole access end or the voltage value of the first end of the charger capacitor;

[0130] The acquisition module 401 is further configured to obtain a second voltage difference between the battery negative - pole access end and the neutral line when the second end of the battery switch device is electrically connected to the battery negative - pole access end; the voltage value of the battery negative - pole access end is the negative - pole voltage value of the battery connected to the battery negative - pole access end or the voltage value of the second end of the charger capacitor;

[0131] A processing module 402, configured to determine a battery switch device failure when an absolute value of a difference between a first voltage difference and a second voltage difference is less than or equal to a first preset voltage difference.

[0132] In a feasible embodiment, the processing module 402 is further configured to control a precharge circuit to conduct before the acquisition module 401 acquires a first voltage difference between a second end of the mains switch device and the neutral line, so as to precharge a bus capacitor for an input end of the uninterruptible power supply.

[0133] Wherein, the uninterruptible power supply further includes a precharge circuit and a bus capacitor, and the input end of the uninterruptible power supply, the precharge circuit, the bus capacitor, and the neutral line are connected in series electrically.

[0134] In another feasible embodiment, the acquisition module 401 is further configured to acquire an access state of the battery; the access state includes an access state or a non-access state.

[0135] The processing module 402 is further configured to, when the battery is in a non-access state and a voltage difference between two ends of a charger capacitor is less than a second preset voltage difference, control a battery charging circuit to charge the charger capacitor until the voltage difference between two ends of the charger capacitor is a third voltage difference, and conduct a first charging switch device and a second charging switch device after the charging is completed.

[0136] Wherein, the uninterruptible power supply includes a battery charging circuit, a first charging switch device, and a second charging switch device. A first charging switch device is connected in series between a battery positive electrode access end and a first end of the charger capacitor, a second charging switch device is connected in series between a battery negative electrode access end and a second end of the charger capacitor, a first end and a second end of the battery charging circuit are electrically connected to the charger capacitor, and a third end and a fourth end of the battery charging circuit are electrically connected to the bus capacitor.

[0137] The third voltage difference is greater than or equal to the second preset voltage difference and less than a third preset voltage difference, and the third preset voltage difference is determined based on a bus voltage across the bus capacitor.

[0138] In another feasible embodiment, the processing module 402 is specifically configured to, after the uninterruptible power supply is powered on, acquire a voltage difference between a battery positive electrode access end and a battery negative electrode access end.

[0139] When the voltage difference between the battery positive electrode access end and the battery negative electrode access end is less than the second preset voltage difference, it is determined that the battery is in a non-access state.

[0140] When the voltage difference between the battery positive electrode access end and the battery negative electrode access end is greater than or equal to the second preset voltage difference, it is determined that the battery is in an access state.

[0141] In another feasible embodiment, the processing module 402 is specifically configured to charge the charger capacitor with the electric energy stored in the bus capacitor by controlling the battery charging circuit.

[0142] In another feasible embodiment, the processing module 402 is further configured to close the mains switch device of the uninterruptible power supply to control the operation of the uninterruptible power supply when the absolute value of the difference between the first voltage difference and the second voltage differences corresponding to the respective battery switch devices is greater than a first preset voltage difference.

[0143] Figure 8 FIG. is a schematic structural diagram of a controller provided according to an embodiment of the present application. Among them, the controller 500 includes a memory 501 and a processor 502. The memory 501 is used to store computer instructions executable by the processor. The memory 501 may include a high-speed random access memory (Random Access Memory, RAM), and may also include non-volatile storage (Non-Volatile Memory, NVM), such as at least one disk memory, and may also be a USB flash drive, a mobile hard disk, a read-only memory, a magnetic disk, or an optical disc, etc.

[0144] The processor 502 implements each step in the fault detection method of the uninterruptible power supply with the controller as the execution subject in the above embodiment when executing the computer instructions. Specifically, reference may be made to the relevant descriptions in the foregoing method embodiments. The processor 502 may be a central processing unit (Central Processing Unit, CPU), and may also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application-specific integrated circuits (ApplicationSpecific Integrated Circuit, ASIC), etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the invention can be directly embodied as being executed and completed by a hardware processor, or executed and completed by a combination of hardware and software modules in the processor.

[0145] Optionally, the above-mentioned memory 501 can be either independent or integrated with the processor 502. When the memory 501 is independently provided, the controller 500 further includes a bus for connecting the memory 501 and the processor 502. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0146] The embodiments of the present application further provide a computer-readable storage medium. Computer instructions are stored in the computer-readable storage medium. When the processor executes the computer instructions, each step of the fault detection method of the uninterruptible power supply in the above embodiments is implemented.

[0147] The embodiments of the present application further provide a computer program product, including computer instructions. When the computer instructions are executed by the processor, each step of the fault detection method of the uninterruptible power supply in the above embodiments is implemented.

[0148] Those skilled in the art will readily think of other implementation manners of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and the embodiments are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the following claims.

[0149] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A fault detection method for an uninterruptible power supply, characterized in that, The method is applied to an uninterruptible power supply, which includes a battery switch device, a mains switch device, and a charger capacitor. The input end of the uninterruptible power supply, the mains switch device, and the first end of the battery switch device are sequentially connected in series electrically. The second end of the battery switch device is electrically connected to the battery positive terminal access end or the battery negative terminal access end of the uninterruptible power supply. The battery positive terminal access end is coupled to the first end of the charger capacitor, and the battery negative terminal access end is coupled to the second end of the charger capacitor; The method includes: Before closing the mains switch device, obtain a first voltage difference between the second end of the mains switch device and the neutral line. The second end of the mains switch device is electrically connected to the first end of the battery switch device; When the second end of the battery switch device is electrically connected to the battery positive terminal access end, obtain a second voltage difference between the battery positive terminal access end and the neutral line. The voltage value of the battery positive terminal access end is the positive voltage value of the battery connected to the battery positive terminal access end or the voltage value of the first end of the charger capacitor; When the second end of the battery switch device is electrically connected to the battery negative terminal access end, obtain a second voltage difference between the battery negative terminal access end and the neutral line. The voltage value of the battery negative terminal access end is the negative voltage value of the battery connected to the battery negative terminal access end or the voltage value of the second end of the charger capacitor; When the absolute value of the difference between the first voltage difference and the second voltage difference is less than or equal to a first preset voltage difference, determine that the battery switch device is faulty.

2. The method according to claim 1, wherein The uninterruptible power supply further includes a pre-charge circuit and a bus capacitor. The input end of the uninterruptible power supply, the pre-charge circuit, the bus capacitor, and the neutral line are connected in series electrically; Before obtaining the first voltage difference between the second end of the mains switch device and the neutral line, the method further includes: Control the pre-charge circuit to conduct, so that the input end of the uninterruptible power supply pre-charges the bus capacitor.

3. The method according to claim 2, wherein The uninterruptible power supply further includes a battery charging circuit, a first charging switch device, and a second charging switch device. The first charging switch device is connected in series between the battery positive terminal access end and the first end of the charger capacitor. The second charging switch device is connected in series between the battery negative terminal access end and the second end of the charger capacitor. The first end and the second end of the battery charging circuit are electrically connected to the charger capacitor. The third end and the fourth end of the battery charging circuit are electrically connected to the bus capacitor; Before obtaining the second voltage difference between the battery positive terminal access end and the neutral line and obtaining the second voltage difference between the battery negative terminal access end and the neutral line, the method further includes: Obtain the access state of the battery. The access state includes an access state or a non-access state; When the battery is in the unconnected state and the voltage difference across the charger capacitor is less than a second preset voltage difference, control the battery charging circuit to charge the charger capacitor until the voltage difference across the charger capacitor is a third voltage difference, and turn on the first charging switch device and the second charging switch device after the charging is completed; The third voltage difference is greater than or equal to the second preset voltage difference.

4. The method according to claim 3, characterized in that, The third voltage difference is less than a third preset voltage difference, and the third preset voltage difference is determined based on the bus voltage across the bus capacitor.

5. The method according to claim 3 or 4, characterized in that Obtaining the connection state of the battery includes: After the uninterruptible power supply is powered on, obtain the voltage difference between the positive battery connection terminal and the negative battery connection terminal; When the voltage difference between the positive battery connection terminal and the negative battery connection terminal is less than the second preset voltage difference, determine that the battery is in the unconnected state; When the voltage difference between the positive battery connection terminal and the negative battery connection terminal is greater than or equal to the second preset voltage difference, determine that the battery is in the connected state.

6. The method according to claim 3 or 4, characterized in that, Controlling the battery charging circuit to charge the voltage difference across the charger capacitor to the third voltage difference includes: The battery charging circuit charges the charger capacitor using the electrical energy stored in the bus capacitor.

7. The method according to any one of claims 1 to 4, characterized in that After obtaining the second voltage difference, the method further includes: When the absolute value of the difference between the first voltage difference and the second voltage differences corresponding to each battery switch device is greater than a first preset voltage difference, close the mains switch device of the uninterruptible power supply to control the operation of the uninterruptible power supply.

8. A fault detection device for an uninterruptible power supply, characterized in that, Includes: An acquisition module, configured to obtain a first voltage difference between the second terminal of the mains switch device and the neutral line before closing the mains switch device; wherein, the mains switch device is located in the uninterruptible power supply, and the uninterruptible power supply further includes battery switch devices and a charger capacitor. The input end of the uninterruptible power supply is electrically connected to the first terminal of the mains switch device, the second terminal of the mains switch device is electrically connected to the battery switch devices, the second terminal of the battery switch devices is electrically connected to the positive battery connection terminal or the negative battery connection terminal of the uninterruptible power supply, the positive battery connection terminal is coupled to the first terminal of the charger capacitor, and the negative battery connection terminal is coupled to the second terminal of the charger capacitor; The acquisition module is further configured to obtain a second voltage difference between the positive battery connection terminal and the neutral line when the second terminal of the battery switch device is electrically connected to the positive battery connection terminal; the voltage value of the positive battery connection terminal is the positive voltage value of the battery connected to the positive battery connection terminal or the voltage value of the first terminal of the charger capacitor; The acquisition module is further configured to obtain a second voltage difference between the negative battery connection terminal and the neutral line when the second terminal of the battery switch device is electrically connected to the negative battery connection terminal; the voltage value of the negative battery connection terminal is the negative voltage value of the battery connected to the negative battery connection terminal or the voltage value of the second terminal of the charger capacitor; A processing module, configured to determine that the battery switch device fails when an absolute value of a difference between the first voltage difference and the second voltage difference is less than or equal to a first preset voltage difference.

9. The device according to claim 8, wherein: The processing module is further configured to control a precharge circuit to conduct before the acquisition module obtains a first voltage difference between a second end of the mains switch device and a neutral line, so as to precharge a bus capacitor for an input end of the uninterruptible power supply; Wherein, the uninterruptible power supply further includes the precharge circuit and the bus capacitor, and an input end of the uninterruptible power supply, the precharge circuit, the bus capacitor, and the neutral line are connected in series electrically.

10. A controller, characterized in that, Comprising: A processor and a memory communicatively connected to the processor; The memory stores computer-executable instructions; When executing the computer-executable instructions, the processor is configured to implement the method according to any one of claims 1 to 7.

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