CN115776170A - Uninterruptible power supply, power supply method and power supply system - Google Patents

Abstract

The application provides an uninterruptible power supply, a power supply method and a power supply system, whether energy reverse irrigation exists in a load connected with the uninterruptible power supply is detected in real time, and when the fact that the energy reverse irrigation exists in the load is determined, a charge-discharge module is controlled to directly charge the energy in the reverse irrigation to a battery pack connected with the uninterruptible power supply, so that the uninterruptible power supply can support the energy reverse irrigation of the load, and the application range of the uninterruptible power supply is expanded. In addition, the charge and discharge module inside the uninterruptible power supply originally supports the charge and discharge functions, and the energy reversely irrigated by the load can be stored in the battery pack without upgrading the configuration of the charge and discharge module. And the load reverse-flow energy stored in the battery pack can be used for supplying power to the load subsequently, so that the energy is effectively utilized, and the energy consumption can be saved.

Description

Uninterruptible power supply, power supply method and power supply system

Technical Field

The present application relates to the field of power technologies, and in particular, to an uninterruptible power supply, a power supply method, and a power supply system.

Background

An Uninterruptible Power Supply (UPS) system is a system that can supply power to a load without interruption instead of a power grid when a power grid fails (e.g., power failure, undervoltage, interference, or surge), and maintain the normal operation of the load. Specifically, the uninterruptible power supply system mainly comprises an uninterruptible power supply and a battery pack, wherein the uninterruptible power supply is respectively connected with a power grid, a load and the battery pack. The uninterrupted power supply can monitor the working state of the power grid, and when the power grid works normally, the uninterrupted power supply can supply power to a load by using the electric energy provided by the power grid; when the power grid fails, the uninterruptible power supply can control the battery pack to discharge, and the electric energy output by the battery pack is used for continuously supplying power to the load.

In some application scenarios, a load may back-charge the ups with energy. For example, the output of the ups drives a motor load, and when the motor brakes and decelerates, the motor will reverse-flow energy to the ups, which may cause overvoltage protection of the bus capacitor voltage inside the ups, and thus cause interruption of the output power supply of the ups.

Disclosure of Invention

The application provides an uninterruptible power supply, a power supply method and a power supply system, which are used for supporting load energy reverse irrigation on the basis of not increasing the system cost.

In a first aspect, the present application provides an uninterruptible power supply, including a control module and a charge and discharge module; the uninterruptible power supply can also comprise components such as a rectifier, a bus capacitor, an inverter and the like. The charging and discharging module is used for connecting the battery pack so as to charge or discharge the battery pack. The charging and discharging module can comprise a charging loop and a discharging loop which are mutually independent, the charging loop independently realizes the charging function of the battery pack, and the discharging loop independently realizes the discharging function of the battery pack; alternatively, the charging and discharging module may include a charging and discharging loop integrated in the same hardware to implement the charging or discharging function. The control module is used for controlling the charge-discharge module to charge the reversely charged energy to the battery pack when the situation that the load connected with the uninterruptible power supply has the energy reverse charge is determined, so that the overvoltage of a direct-current bus of the uninterruptible power supply is avoided, the uninterruptible power supply can support the load energy reverse charge, and the application range of the uninterruptible power supply is expanded. And the charge-discharge module in the uninterruptible power supply originally supports the charge and discharge functions, and the control module can directly control the charge-discharge module to store the energy reversely charged by the load to the battery pack. And the load reverse-flow energy stored in the battery pack can be used for supplying power to the load subsequently, so that the energy is effectively utilized, and the energy consumption can be saved.

In one possible implementation manner of the present application, in order to ensure that the load reverse-charging energy can be charged to the battery pack, when the parameters of the uninterruptible power supply are configured, it can be ensured that the maximum charging power of the charging and discharging module is greater than the maximum energy reverse-charging power of the load connected to the uninterruptible power supply, so that the load reverse-charging energy can be fully charged to the battery pack.

In a possible implementation manner of the present application, in order to ensure that the uninterruptible power supply can continuously cope with the load energy recharging, after each time of the load energy recharging, the control module may perform appropriate discharging according to a current electric quantity parameter condition of the battery pack, that is, the control module is further configured to control the charging and discharging module to discharge the battery pack until the electric quantity parameter is not greater than the first set value when it is determined that the load does not have the energy recharging and it is determined that the electric quantity parameter of the battery pack is greater than the first set value, so as to ensure that there is sufficient spare capacity in the battery pack to support the next load energy recharging.

In one possible implementation manner of the present application, the parameter of the electric quantity includes parameters such as SOC of the battery pack, or battery voltage of the battery pack, or real-time capacity of the battery pack. When the electric quantity parameter selects the SOC, the first set value can be set to be a percentage smaller than 1, and when the SOC is larger than the first set value, the SOC value needs to be reduced, namely the battery pack is discharged to enable the SOC value to be equal to the first set value, which indicates that the empty residual capacity in the battery pack is small and is not enough to accommodate the reverse charging energy of the load next time. When the battery voltage is selected as the electric quantity parameter, the first setting value may be set to be smaller than a voltage value after the battery pack is fully charged, and when the battery voltage is larger than the first setting value, it indicates that the empty residual capacity of the battery pack is small and insufficient to accommodate the next load reverse charging energy, the battery voltage needs to be reduced, that is, the battery pack is discharged to make the battery voltage value equal to the first setting value. When the real-time capacity is selected as the electric quantity parameter, the first set value can be set to be smaller than the total capacity value of the battery pack, and when the real-time capacity is larger than the first set value, the real-time capacity needs to be reduced if the empty residual capacity of the battery pack is small and is not enough to accommodate the reverse charge energy of the next load, namely the battery pack is subjected to discharge operation to enable the voltage value of the battery to be equal to the first set value.

In one possible implementation manner of the present application, when the first setting value is selected, the maximum single energy back-flow value of the load and the battery capacity of the battery pack may be referred to. The larger the maximum value of the single energy of the load is, which indicates that the more the single energy of the load is, the more the spare capacity of the battery pack needs to be maintained, that is, the first set value needs to be in a negative correlation with the maximum value of the single energy of the load. The larger the battery capacity of the battery pack is, the more the total electric quantity that can be accommodated by the battery pack is, and the larger the first setting value can be, that is, the first setting value has a positive correlation with the battery capacity of the battery pack.

In one possible implementation manner of the present application, when a power supply failure occurs in a power grid, the uninterruptible power supply continues to supply power to the load by using the electric energy provided by the battery pack, because the battery pack is used to supply power to the load, the electric quantity parameter of the battery pack will continuously decrease, and after the power grid recovers to normal power supply, the electric quantity parameter of the battery pack will decrease to be smaller than the first set value, at this time, the control module is further configured to control the charge-discharge module to charge the battery pack until the electric quantity parameter equals to the first set value, so as to ensure that the battery pack stores sufficient electric energy to continuously supply power to the load after the subsequent power grid failure occurs.

In a possible implementation manner of the present application, the control module may be specifically configured to detect whether an output power of an inverter in the uninterruptible power supply is a negative value in real time, and if the output power of the inverter is a positive value, it indicates that the inverter provides electric energy to the load, and if the output power of the inverter is a negative value, it indicates that the load provides electric energy to the inverter, that is, it is determined that the load has energy back-flow. Or, the control module may be specifically configured to detect whether the voltage value of the bus capacitor is higher than a second set value in real time, where the bus capacitor plays a role in storing electric energy and stabilizing voltage, and the voltage value of the bus capacitor is related to the magnitude of electric energy provided by the bus, when the bus is normally powered, the voltage value of the bus capacitor is a normal voltage value, the second set value takes a value between the normal voltage value and a tolerable maximum voltage value, and if the voltage value of the bus capacitor is lower than the second set value, it is determined that the bus normally provides electric energy, and if the voltage value of the bus capacitor is higher than the second set value, it is determined that energy on the bus is too large, that is, it is determined that energy backflow exists in the load.

In a second aspect, the present application provides a method for supplying power to an uninterruptible power supply, including: the method comprises the steps of detecting whether energy reverse irrigation exists in a load connected with the uninterruptible power supply in real time, and controlling the charge-discharge module to directly charge reverse irrigation energy to a battery pack connected with the uninterruptible power supply when the load is determined to have the energy reverse irrigation, so that the application range of the uninterruptible power supply is expanded. In addition, the charge and discharge module in the uninterruptible power supply originally supports the charge and discharge functions, the energy reversely charged by the load can be stored in the battery pack without upgrading the configuration of the charge and discharge module, so that the rectifier in the uninterruptible power supply does not need to support the bidirectional flow of the energy, an energy release circuit does not need to be added in the uninterruptible power supply, and the system cost can be saved. And the load reverse-flow energy stored in the battery pack can be used for supplying power to the load subsequently, so that the energy is effectively utilized, and the energy consumption can be saved.

In a possible implementation manner of the present application, in order to ensure that the uninterruptible power supply can continuously cope with the load energy reverse flow, after each load energy reverse flow is ended, the battery pack can be properly discharged according to the current electric quantity parameter condition of the battery pack, that is, when it is determined that the load does not have the energy reverse flow, and when it is determined that the electric quantity parameter of the battery pack is greater than the first set value, the charge-discharge module is controlled to discharge the battery pack until the electric quantity parameter is not greater than the first set value, so as to ensure that sufficient spare capacity in the battery pack can support the next load energy reverse flow.

In one possible implementation manner of the present application, the parameter of the electric quantity may include parameters such as an SOC of the battery pack, or a battery voltage of the battery pack, or a real-time capacity of the battery pack. When the SOC is greater than the first set value, which indicates that the empty capacity of the battery pack is small and insufficient to accommodate the next load back-charging energy, the SOC value needs to be reduced, that is, the battery pack is discharged to make the SOC value equal to the first set value. When the battery voltage is selected as the electric quantity parameter, the first setting value may be set to be smaller than a voltage value after the battery pack is fully charged, and when the battery voltage is larger than the first setting value, it indicates that the empty residual capacity of the battery pack is small and insufficient to accommodate the next load reverse charging energy, the battery voltage needs to be reduced, that is, the battery pack is discharged to make the battery voltage value equal to the first setting value. When the real-time capacity is selected as the electric quantity parameter, the first set value can be set to be smaller than the total capacity value of the battery pack, and when the real-time capacity is larger than the first set value, the real-time capacity needs to be reduced if the empty residual capacity of the battery pack is small and is not enough to accommodate the reverse charge energy of the next load, namely the battery pack is subjected to discharge operation to enable the voltage value of the battery to be equal to the first set value.

In one possible implementation manner of the present application, when the first setting value is selected, the maximum single energy back-flow value of the load and the battery capacity of the battery pack may be referred to. The larger the maximum single-energy reverse-charging value of the load is, the more the single-energy reverse-charging value is, the more the vacant capacity of the battery pack needs to be kept is, and the first set value needs to be in a negative correlation with the maximum single-energy reverse-charging value of the load. The larger the battery capacity of the battery pack is, the more the total electric quantity that can be accommodated by the battery pack is, and the larger the first setting value can be, that is, the positive correlation between the first setting value and the battery capacity of the battery pack is.

In one possible implementation manner of the present application, when a power grid fails, the uninterruptible power supply may continue to supply power to the load using the electric energy provided by the battery pack, because the battery pack is used to supply power to the load, the electric quantity parameter of the battery pack may continuously decrease, and after the power grid recovers to normal power supply, the electric quantity parameter of the battery pack may decrease to be smaller than a first set value, at this time, the power grid may supply power to the battery pack through the charge-discharge module, that is, the charge-discharge module is controlled to charge the battery pack until the electric quantity parameter is equal to the first set value, so as to ensure that the battery pack stores sufficient electric energy to continuously supply power to the load after a subsequent power grid failure occurs. The first setting value may be considered as an upper limit of charging of the battery pack by the power grid, that is, the charging and discharging module stops the charging state after the battery pack is charged to the first setting value.

In a possible implementation manner of the present application, detecting whether energy back-filling exists in a load connected to an uninterruptible power supply in real time may specifically be implemented in the following two manners: the method I comprises the following steps: detecting whether the output power of an inverter in the uninterruptible power supply is a negative value or not in real time, wherein if the output power of the inverter is a positive value, the inverter is indicated to provide electric energy for the load, and if the output power of the inverter is a negative value, the load is indicated to provide the electric energy for the inverter, namely, the load is determined to have energy back-filling. The second method comprises the following steps: the method comprises the steps of detecting whether the voltage value of a bus capacitor in the uninterruptible power supply is higher than a second set value in real time, enabling the bus capacitor to play a role in storing electric energy and stabilizing voltage, enabling the voltage value of the bus capacitor to be related to the size of the electric energy provided by a bus, enabling the voltage value of the bus capacitor to be a normal voltage value when the uninterruptible power supply is normally powered, enabling the second set value to be a value between the normal voltage value and a tolerable maximum voltage value, indicating that the bus normally provides the electric energy when the voltage value of the bus capacitor is lower than the second set value, and indicating that the energy on the bus is overlarge when the voltage value of the bus capacitor is higher than the second set value, namely determining that the energy reverse filling exists in a load.

In a third aspect, the present application further provides a power supply system, including: the first aspect provides any one of the uninterrupted power supply and the battery pack connected with the uninterrupted power supply. Because the battery pack may have frequent charging and discharging processes, a battery type suitable for frequent charging and discharging is generally selected, for example, a lithium battery may be selected.

According to the uninterruptible power supply, the power supply method and the power supply system, whether energy reverse irrigation exists in a load connected with the uninterruptible power supply is detected in real time, and when the fact that the energy reverse irrigation exists in the load is determined, the charge-discharge module is controlled to directly charge the energy reverse irrigation to the battery pack connected with the uninterruptible power supply, so that the uninterruptible power supply can support the energy reverse irrigation of the load, and the application range of the uninterruptible power supply is expanded. Moreover, the charge and discharge module in the uninterruptible power supply originally supports the charge and discharge functions, and the energy reversely charged by the load can be stored in the battery pack without upgrading the configuration of the charge and discharge module. And the load back-flowing energy stored to the battery pack can be used for supplying power to the load subsequently, so that the energy is effectively utilized, and the energy consumption can be saved.

Drawings

Fig. 1 is a schematic diagram of an internal structure of an uninterruptible power supply provided in the prior art;

fig. 2 is a schematic diagram of an internal structure of another ups provided in the prior art;

fig. 3 is a schematic diagram of an internal structure of another ups provided by the prior art;

fig. 4 is a schematic structural diagram of an uninterruptible power supply according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram illustrating a flow of power of an ups according to an embodiment of the present invention during a reverse energy flow;

fig. 6 is a schematic diagram illustrating a flow direction of electric energy discharged by a battery pack after an energy recharging process of the ups according to the embodiment of the present application is completed;

fig. 7 is a schematic diagram illustrating a flow of electric energy for charging a battery pack when the ups provided by an embodiment of the present application is normally powered by a power grid;

fig. 8 is a schematic diagram illustrating SOC variation of a battery pack connected to an uninterruptible power supply in different periods according to an embodiment of the present disclosure;

fig. 9 is a schematic flowchart of a method for supplying power to an uninterruptible power supply according to an embodiment of the present disclosure.

Reference numerals:

10-an uninterruptible power supply; 20-a power grid; 30-load; 40-a battery pack; 11-a rectifier; 12-bus capacitance; 13-an inverter; 14-a charge-discharge module; 15-a bypass switch; 16-an energy bleed-off circuit; 17-a control module.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be further described in detail with reference to the accompanying drawings. The particular methods of operation in the method embodiments may also be applied in device embodiments or system embodiments. It is to be noted that "at least one" in the description of the present application means one or more, where a plurality means two or more. In view of this, the "plurality" may also be understood as "at least two" in the embodiments of the present invention. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" generally indicates that the preceding and following related objects are in an "or" relationship, unless otherwise specified. It is to be understood that the terms "first," "second," and the like, in the description of the present application, are used for distinguishing between descriptions and not necessarily for describing a sequential or chronological order, or for indicating or implying a relative importance.

In modern society, a large number of devices which operate depending on electric power, such as household appliances, data centers and factory production lines, are filled, and the supply of electric power becomes one of the factors for maintaining the normal operation of the modern society. Therefore, a large-scale power grid is established in the country, and electric energy generated by the power plant can be transmitted to equipment needing electric power to operate.

However, the power grid may have a risk of power interruption, and when the power of the power grid is interrupted, the power grid may damage equipment, and the use experience of people is also affected. For example, when a data center is suddenly powered down, important data may be lost. When the electric lamp is powered off suddenly, night illumination of people can be affected, and inconvenience is brought to life of people. Namely, various accidental abnormalities or power failure possibly existing in the power grid cannot provide stable power supply guarantee for the load.

In view of this, the uninterruptible power supply system is now and more widely used, and when the power grid is abnormal, the uninterruptible power supply continues to provide electric energy for the load through the energy storage components such as the battery or the flywheel, so as to ensure the power utilization safety of the load. Fig. 1 schematically illustrates an internal structure of an uninterruptible power supply. As shown in fig. 1, an uninterruptible power supply 10 is connected to a power grid 20, a load 30, and a battery pack 40, respectively, and the uninterruptible power supply 10 mainly includes a rectifier (AC/DC) 11, a bus capacitor 12, an inverter (DC/AC) 13, and a charge-discharge module (DC/DC) 14 connected to a bus line at a main input. When the power grid 20 is in normal input, the uninterruptible power supply 10 converts and stabilizes the power supplied by the power grid 20 through the AC/DC11 and the DC/AC13, and supplies the power to the load 30, and simultaneously charges the battery pack 40 through the DC/DC 14. When the power grid 20 is interrupted (or power failure occurs), the ups 10 provides the DC power of the battery pack 40 to the load 30 through DC/DC14 and DC/AC13 conversion and voltage stabilization. In some application scenarios, as a backup of the power supply link, the ups 10 may further include a bypass switch 15 connected to a bus of the bypass input, and when the bypass input is normal, the power provided by the grid 20 may also directly supply the load 30 with power from the bypass input through the bypass switch 15.

The power grid 20 may be a city power grid, a photovoltaic power grid, a micro-grid, a household power grid, an industrial power grid, or the like, and the power grid 20 may continuously supply power to the uninterruptible power supply 10. There are many possibilities for the power supplied by the power grid 20 to the ups 10, for example, it may be ac power, dc power, high frequency ac power, low frequency ac power, high voltage ac power, or low voltage ac power, and the power supplied by the power grid 20 to the ups 10 is mainly determined by the type of the power grid 20, which is not limited in this application.

The ups 10 may use the power provided by the grid 20 to power the load 30 while the grid 20 remains powered. Specifically, in one possible implementation, the grid 20 may directly forward the power provided by the grid 20 to the load 30 through the bypass input, for example, if the grid 20 inputs 220V and 50HZ ac power to the ups 10, the ups 10 directly outputs 220V and 50HZ ac power to the load 30 through the bypass input.

In another possible implementation, the ups 10 may also convert the power provided by the grid 20, such as one or more of rectification conversion, inversion conversion, boost conversion, and buck conversion, so as to output the power adapted to the load 30. For example, when the grid 20 inputs ac power to the ups 10 and the load 30 is a dc load, the ups 10 may rectify and convert the ac power provided by the grid 20, convert the ac power into dc power, and provide the dc power to the load 30. If the dc power voltage obtained through the rectification and conversion is high and the load 30 is a low-voltage dc load, the uninterruptible power supply 10 may further perform voltage reduction and conversion on the dc power to obtain low-voltage dc power, and then provide the low-voltage dc power to the load 30.

The ups 10 may continuously monitor the power state of the grid 20 while the grid 20 remains powered. When the power grid 20 fails, the ups 10 may continue to supply power to the load 30 using power provided by the battery pack 40. It is noted that "grid 20 power failure" is understood to be a condition where the ups 10 is unable to receive normal power from the grid 20. For example, the uninterruptible power supply 10 does not receive power from the power grid 20, or the power supplied by the power grid 20 has a voltage sag (the input voltage of the power grid 20 is 15% -20% lower than the nominal voltage and lasts for several seconds), or the power supplied by the power grid 20 has a surge (the input voltage of the power grid 20 is 10% higher than the nominal voltage and lasts for several seconds), or there is a serious disturbance in the power supplied by the power grid 20, and so on, and these abnormal situations can be understood as "power failure of the power grid 20".

When the uninterruptible power supply 10 continues to supply power to the load 30 using the electric energy provided by the battery pack 40, the uninterruptible power supply may directly forward the electric energy provided by the battery pack 40 to the load 30, or may convert the electric energy provided by the battery pack 40, such as one or more of inversion conversion, boost conversion, and buck conversion, so as to output the electric energy adapted to the load 30. For example, the load 30 is an ac load, and the ups 10 may perform an inverter conversion on the dc power provided by the battery pack 40 to obtain ac power, and provide the ac power to the load 30.

The battery pack 40 may include a plurality of batteries, and the battery pack 40 supplies power to the ups 10, and it is understood that the plurality of batteries output power to the ups 10 in parallel. Generally, the cells in the battery pack 40 may be secondary cells. During the time that the power grid 20 remains powered, the ups 10 may charge the battery pack 40 with power provided by the power grid 20. In the event of a power failure of the power grid 20, the battery pack 40 may release the stored power to the ups 10 so that the ups 10 may maintain uninterrupted power to the load 30.

The ups 10 may also continuously monitor the state of the power supply on the grid 20 during the time that the battery pack 40 is being used to provide power. After the power grid 20 is restored, the ups 10 may convert the power grid 20 to supply power, and continue to supply power to the load 30 using the power supplied by the power grid 20.

The load 30 operates using power supplied by the ups 10. It should be understood that different implementations of load 30 are possible depending on the application scenario. The load 30 may be, for example, a household appliance such as a refrigerator, a washing machine, an air conditioner, an electric lamp, and the like. In this case, the power grid 20 may be a house-to-house power grid, and the uninterruptible power supply system may provide uninterrupted power to the household appliance. As another example, the load 30 may be a cell, in which case the grid 20 may be a city grid, and the uninterruptible power supply system may provide uninterrupted power to all residents in the cell. Also for example, the load 30 may be a data center, in which case the power grid 20 may be an industrial power grid and the uninterruptible power supply system may provide uninterruptible power to the data center. There are many possible application scenarios for uninterruptible power supply systems, which are not listed. In the case where the load 30 is, for example, a motor, the motor will back-charge the ups 10 when the motor is braking, as shown by the arrow in fig. 1, the back-charged energy may cause overvoltage protection of the bus capacitor inside the ups, which may cause the ups to output power supply interruption.

Fig. 2 is a schematic diagram illustrating an internal structure of another ups. In order to realize that the ups 10 can support the back-filling of the load 30, as shown in fig. 2, one conventional way is that the AC/DC11 in the ups 10 can support the back-filling of the energy, which is fed back to the grid 20 by the load 30, as shown by the arrow in fig. 2. The cost of the AC/DC11 part capable of supporting the energy feedback is high, and the scheme is effective only when the power grid 20 is normal, and cannot feed the energy reversely irrigated by the load 30 back to the power grid 20 when the power grid 20 is abnormal, namely, is ineffective when the power grid 20 is abnormal.

Fig. 3 is a schematic diagram illustrating an internal structure of another ups. In order to realize that the ups 10 can support the reverse charging of the energy of the load 30, as shown in fig. 3, another conventional solution is to provide an energy discharge circuit 16 inside the ups 10, and consume the energy reversely charged by the load 30 through the energy discharge circuit 16. Providing the energy discharge loop 16 within the ups 10 increases the size and cost of the ups 10, and energy is consumed by the energy discharge loop 16, which may result in excessive internal temperatures of the ups 10.

In view of this, embodiments of the present application provide a new uninterruptible power supply, a power supply method, and a power supply system, which can implement energy back-filling of a support load of the uninterruptible power supply, so that a voltage of a dc bus inside the uninterruptible power supply is not over-voltage, and a system cost is not increased.

Fig. 4 schematically illustrates a structure of an uninterruptible power supply according to an embodiment of the present application. Referring to fig. 4, in an embodiment of the present application, the ups 10 mainly includes a control module 17 and a charge-discharge module 14.

The charge-discharge module 14 is used for connecting the battery pack 40 to charge or discharge the connected battery pack 40. The charge-discharge module 14 may include a charge circuit and a discharge circuit that are independent of each other, where the charge circuit independently realizes the charge function of the battery pack 40, and the discharge circuit independently realizes the discharge function of the battery pack 40. Alternatively, the charge-discharge module 14 may also include a charge-discharge circuit integrated in the same hardware to implement a charging or discharging function, which is not limited herein.

The control module 17 is configured to control the charge-discharge module 14 to charge the battery pack 40 with energy flowing backward when it is determined that the load 30 connected to the ups 10 has energy flowing backward, so as to avoid overvoltage of the dc bus of the ups 10, so that the ups 10 can support the energy flowing backward of the load 30, and the application range of the ups 10 can be expanded. And the charge-discharge module 14 inside the ups 10 originally supports the charging and discharging functions, the control module 17 can directly control the charge-discharge module 14 to store the energy reversely charged by the load 30 into the battery pack 40, and the energy reversely charged by the load 30 can be stored into the battery pack 40 without upgrading the configuration of the charge-discharge module 14. And the energy stored in the battery pack 40 can be used for supplying power to the load 30 subsequently, so that the recharging energy is effectively utilized, and the energy consumption can be saved.

Fig. 5 is a schematic diagram illustrating a flow of power of an uninterruptible power supply provided by an embodiment of the present application when the power is reversely charged. In a specific implementation manner, referring to fig. 5, the uninterruptible power supply 10 is connected to the load 30 and the battery pack 40, the uninterruptible power supply 10 includes the charge-discharge module 14, and may further include components such as the rectifier 11, the bus capacitor 12, and the inverter 13, and the control module 17 has signal interaction with the components such as the rectifier 11, the bus capacitor 12, the inverter 13, and the charge-discharge module 14, and connection relationships between the control module 17 and these components are not shown in fig. 5 to 7 for convenience of viewing. In the system shown in fig. 5, there are three cases of supplying power to the load 30, which are: the power supply method includes the case that the power grid 20 supplies power to the load 30 after the electric energy input by the main circuit is subjected to rectification processing by the rectifier 11 and inversion processing by the inverter 13, or the case that the power grid 20 supplies power to the load 30 after the electric energy stored in the battery pack 40 is subjected to discharge processing by the charge-discharge module 14 and the inversion processing by the inverter 13 in the case of power supply failure, and the case that the power grid 20 and the electric energy output by the battery pack 40 supply power to the load 30 after the electric energy is subjected to inversion processing by the inverter 13. In any of the three cases, when the inverter 13 supplies the load 30 with the electric energy, the control module 17 may control the charge-discharge module 14 to charge the back-flow energy generated by the load 30 to the battery pack 40 when the back-flow of the energy of the load 30 occurs. It should be noted that in the event of reverse energy charging of the load 30, whether the charging/discharging module 14 is in a charging, discharging or static state, the charging/discharging module may be switched to a charging state to charge the reverse energy charging of the load 30 to the battery pack 40.

In some application scenarios, as a backup of the power supply link, referring to fig. 5, the uninterruptible power supply 10 may further include a bypass input, a bypass switch 15 is disposed on a bus of the bypass input, and the control module 17 may selectively control the power provided by the power grid 20 to directly supply power to the load 30 through the bypass switch 15 via the bypass input. If the load 30 is back-flooded with energy in the case where the bypass input supplies the load 30 with electrical energy, the energy fed back by the load 30 can be fed back to the grid 20 directly via the bypass input, i.e. the electrical energy is transmitted on the bus of the bypass input, instead of being transmitted to the bus of the main input.

In this embodiment, in order to ensure that the back-sink energy of the load 30 can be charged to the battery pack 40 without any excess back-sink energy flowing to the main circuit, when configuring the parameters of the ups 10, it can be ensured that the maximum charging power of the charging and discharging module 14 is greater than the maximum back-sink energy of the load 30 connected to the ups 10, so that the back-sink energy of the load 30 can be fully charged to the battery pack 40 without flowing to the rectifier 11.

In order to ensure that the ups 10 can continuously cope with the energy recharging of the load 30, after each energy recharging of the load 30 is completed, the control module 17 may properly discharge according to the current electric quantity parameter condition of the battery pack 40 to ensure that there is sufficient spare capacity in the battery pack 40 to support the next energy recharging of the load 30. Based on this, in this embodiment of the application, the control module 17 may further control the charge-discharge module 14 to discharge the battery pack 40 until the charge parameter is not greater than the first setting value when it is determined that the energy back-flow does not exist in the load 30 and it is determined that the charge parameter of the battery pack 40 is greater than the first setting value.

Fig. 6 is a schematic diagram illustrating a flow of electric energy discharged by a battery pack after an energy recharging process of an uninterruptible power supply provided by an embodiment of the present application is completed. Referring to fig. 6, when it is determined that the current electric quantity parameter of the battery pack 40 is greater than the first set value, the electric energy output by the battery pack 40 is used to supply power to the load 30 after the discharging process of the charge-discharge module 14 and the inverting process of the inverter 13, that is, the charge-discharge module 14 is controlled to release the electric quantity of the battery pack 40 greater than the first set value. During this period, if the grid 20 is normal, the grid 20 can simultaneously supply the load 30 with the main input power through the rectification process of the rectifier 11 and the inversion process of the inverter 13, that is, during this period, the power output from the grid 20 and the battery pack 40 respectively is processed by the inverter 13 and then supplies the load 30 with the power together. Or, whether the power grid 20 is normal or not, the power supply of the power grid 20 to the load 30 through the main path input electric energy can be stopped, the power supply of the load 30 is only performed by using the electric energy output by the battery pack 40, and after the electric energy parameter discharged by the battery pack 40 is equal to the first set value, if the power grid 20 is normal, the power supply of the load 30 through the main path input electric energy transmission of the power grid 20 is resumed, and the discharging state of the battery pack 40 is stopped.

In this embodiment of the present application, the charge parameter may include a state of charge (SOC) of the battery pack, or a battery voltage of the battery pack, or a real-time capacity of the battery pack. The SOC represents a ratio of an actual charged amount to a total chargeable amount of the battery pack, that is, a ratio of an amount of electricity actually provided by the battery pack in a current state to an amount of electricity that should be provided after the battery pack is fully charged, when the SOC is selected as the electricity parameter, the first set value may be set to a percentage smaller than 1, and when the SOC is greater than the first set value, it indicates that an empty remaining capacity of the battery pack is small and insufficient to accommodate a next load reverse charging energy, the SOC value may be reduced, that is, the battery pack is discharged to make the SOC value equal to the first set value. When the battery voltage is selected as the electric quantity parameter, the first set value can be set to be smaller than the voltage value of the battery pack after the battery pack is fully charged, and when the battery voltage is larger than the first set value, the battery voltage can be reduced, namely the battery voltage is discharged to enable the battery voltage value to be equal to the first set value, which indicates that the empty residual capacity of the battery pack is less and is not enough to accommodate the back-flow energy of the next load. When the real-time capacity is selected as the electric quantity parameter, the first set value can be set to be smaller than the total capacity value of the battery pack, and when the real-time capacity is larger than the first set value, the real-time capacity can be reduced, namely the battery pack is subjected to discharging operation to enable the voltage value of the battery to be equal to the first set value, which indicates that the empty residual capacity of the battery pack is less and is not enough to accommodate the reverse filling energy of the next load.

In this embodiment of the application, when the first setting value is selected, the appropriate first setting value may be determined by referring to the maximum single energy back-flow value of the load and the battery capacity of the battery pack, for example, the first setting value obtained by calculating the maximum single energy back-flow value of the load and the battery capacity of the battery pack based on the setting algorithm, which is not specifically limited by the application. When the uninterruptible power supply is connected with a plurality of loads, the back-filling energy of each load may be different, and at this time, the back-filling energy value corresponding to the load with the maximum required electric energy may be selected as the single energy back-filling maximum value of the load corresponding to the uninterruptible power supply. The larger the maximum value of the single energy of the load is, which indicates that the more the single energy of the load is, the more the spare capacity of the battery pack needs to be maintained, that is, the first set value needs to be in a negative correlation with the maximum value of the single energy of the load. The larger the battery capacity of the battery pack is, the more the total electric quantity that can be accommodated by the battery pack is, and the larger the first setting value can be, that is, the first setting value has a positive correlation with the battery capacity of the battery pack.

Taking the electric quantity parameter as the SOC, if the ups can discharge for 10 minutes according to the rated power to configure the battery pack, and the load reverse-flow power is less than 30% of the rated power of the ups, and the duration of the load reverse-flow energy is less than 30 seconds, then the load reverse-flow energy accounts for 30% of the total energy of the battery pack by 0.5 minutes/10 minutes =1.5%. The first set point needs to be less than 100% -1.5%, and may be set to 95%, for example.

In this embodiment of the present application, the power supply state of the power grid 20 may be continuously monitored during the time when the power grid 20 is kept normally powered. When the power grid 20 fails, the ups 10 may continue to supply power to the load 30 using power provided by the battery pack 40. Because the battery pack 40 is used to supply power to the load 30, the power parameter of the battery pack 40 will continuously decrease, and when the power grid 20 recovers to normal power supply, the power parameter of the battery pack 40 will decrease to be smaller than the first set value, and at this time, the power grid 20 may charge the battery pack 40 through the charge-discharge module 14. Based on this, in this embodiment of the present application, the control module 17 may further control the charge-discharge module 14 to charge the battery pack 40 until the electric quantity parameter is equal to the first set value, so as to ensure that the battery pack 40 stores sufficient electric energy to continuously supply power to the load 30 after the subsequent failure of the power grid 20 occurs.

Fig. 7 is a schematic diagram illustrating a flow of power for charging a battery pack of an uninterruptible power supply provided by an embodiment of the present application when a power grid is normally powered. Referring to fig. 7, in a normal condition of the power grid 20, a part of the electric energy transmitted by the power grid 20 through the main input is rectified by the rectifier 11 and inverted by the inverter 13 to supply power to the load 30, and at the same time, another part of the electric energy transmitted by the power grid 20 through the main input is rectified by the rectifier 11 and charged by the charging and discharging module 14 to charge the battery pack 40 until the electric quantity parameter of the battery pack 40 is equal to the first set value position.

Fig. 8 is a schematic diagram illustrating SOC variation of a battery pack in an uninterruptible power supply at different time periods according to an embodiment of the present application. In the load energy reverse-filling period, the charge-discharge module charges load reverse-filling energy to the battery pack, and the SOC value of the battery pack is greater than a first set value; after the load energy is reversely irrigated, the charge-discharge module discharges the energy of which the SOC is greater than a first set value in the battery pack to a load; when the power grid normally works, the charge-discharge module is in a static state, and the SOC of the battery pack is kept at a first set value; after the power grid fails, the charge-discharge module controls the battery pack to discharge to supply power to the load, and the SOC of the battery pack is smaller than a first set value; and after the power grid is recovered to be normal, the power grid charges the battery pack through the charge-discharge module until the SOC is equal to the first set value position.

In this embodiment of the application, the control module 17 may be specifically configured to detect whether the output power of the inverter 13 in the uninterruptible power supply is a negative value in real time, if the output power of the inverter 13 is a positive value, it indicates that the inverter 13 provides the load 30 with the electric energy, and if the output power of the inverter 13 is a negative value, it indicates that the load 30 provides the inverter 13 with the electric energy, that is, it is determined that the load 30 has energy back-flow. Or, the control module 17 may be further specifically configured to detect whether the voltage value of the bus capacitor 12 is higher than a second set value in real time, where the bus capacitor 12 plays a role in storing and stabilizing electric energy, the voltage value of the bus capacitor 12 is related to the magnitude of the electric energy provided by the bus, when the power is supplied normally, the voltage value of the bus capacitor 12 is a normal voltage value, the second set value takes a value between the normal voltage value and a tolerable maximum voltage value, if the voltage value of the bus capacitor 12 is lower than the second set value, it is determined that the bus normally provides the electric energy, and if the voltage value of the bus capacitor 12 is higher than the second set value, it is determined that the energy on the bus is too large, that is, it may be determined that the load 30 has energy backflow.

Fig. 9 schematically illustrates a flow chart of a method for supplying power to an uninterruptible power supply according to an embodiment of the present application. The main body of the ups power supply method may be the control module 17 in the above description of the embodiment, or a control chip or control software in the ups, which is not limited in this application.

Fig. 9 schematically illustrates a flow chart of a method for supplying power to an uninterruptible power supply according to an embodiment of the present application. Referring to fig. 4, in an embodiment of the present application, the method for supplying power to an uninterruptible power supply mainly includes the following steps:

s101, detecting whether energy backflow exists in a load connected with the uninterruptible power supply in real time; when the load is determined to have energy reverse irrigation, executing the step S102;

and S102, controlling the charge-discharge module to charge the reversely-charged energy to the battery pack connected with the uninterruptible power supply.

According to the uninterruptible power supply method provided by the embodiment of the application, when the situation that the load has energy reverse irrigation is determined, the charge-discharge module is controlled to directly charge the energy reverse irrigation to the battery pack, the overvoltage of a direct current bus in the uninterruptible power supply is avoided, the uninterruptible power supply can support the load energy reverse irrigation, and the application range of the uninterruptible power supply is expanded. In addition, the charge and discharge module inside the uninterruptible power supply originally supports the charge and discharge functions, and the energy reversely irrigated by the load can be stored in the battery pack without upgrading the configuration of the charge and discharge module. And the load reverse-flow energy stored in the battery pack can be used for supplying power to the load subsequently, so that the energy can be effectively utilized, and the energy consumption can be saved.

With reference to fig. 5 to fig. 7, in some application scenarios, as a backup of the power supply link, the uninterruptible power supply has a bypass input, the power grid 20 can directly forward the electric energy provided by the power grid 20 to the load 30 through the bypass input, and at this time, if the energy of the load 30 flows backwards, the energy flowing backwards of the load 30 can be directly fed back to the power grid 20 through the bypass input, that is, the electric energy is transmitted on the bus of the bypass input, and is not transmitted to the bus of the main input.

In this embodiment, in order to ensure that the back-sink energy of the load 30 can be charged to the battery pack 40 without the excess back-sink energy flowing to the main circuit, when configuring the parameters of the ups, it can be ensured that the maximum charging power of the charging and discharging module 14 is greater than the maximum back-sink energy of the load connected to the ups, so that the back-sink energy of the load can be fully charged to the battery pack without flowing to the rectifier 11.

In order to ensure that the uninterruptible power supply can continuously cope with the energy reverse filling of the load, after each load energy reverse filling is finished, the battery pack can be properly discharged according to the current electric quantity parameter condition of the battery pack so as to ensure that sufficient spare capacity in the battery pack can support the energy reverse filling of the next load. Specifically, with continued reference to fig. 9, in this embodiment of the present application, the uninterruptible power supply method may further include the following steps:

when it is determined that the load has no energy reverse irrigation, executing step S103;

s103, determining whether the electric quantity parameter of the battery pack is larger than a first set value; if yes, go to step S104;

and S104, controlling the charge-discharge module to discharge the battery pack until the electric quantity parameter is not greater than a first set value.

In this embodiment of the present application, the parameter of the electric quantity may include parameters such as SOC of the battery pack, or battery voltage of the battery pack, or real-time capacity of the battery pack. When the SOC is greater than the first set value, which indicates that the empty capacity of the battery pack is small and insufficient to accommodate the next load back-charging energy, the SOC value needs to be reduced, that is, the battery pack is discharged to make the SOC value equal to the first set value. When the battery voltage is selected as the electric quantity parameter, the first set value can be set to be smaller than the voltage value of the battery pack after the battery pack is fully charged, and when the battery voltage is larger than the first set value, the battery voltage needs to be reduced if the empty residual capacity of the battery pack is small and is not enough to accommodate the reverse flow energy of the load next time, namely the battery voltage is discharged to enable the battery voltage value to be equal to the first set value. When the real-time capacity is selected as the electric quantity parameter, the first set value can be set to be smaller than the total capacity value of the battery pack, and when the real-time capacity is larger than the first set value, the real-time capacity needs to be reduced if the empty residual capacity of the battery pack is small and is not enough to accommodate the reverse charge energy of the next load, namely the battery pack is subjected to discharge operation to enable the voltage value of the battery to be equal to the first set value.

In this embodiment of the present application, when selecting the first setting value, a suitable first setting value may be determined with reference to the maximum value of the single energy recharge of the load and the battery capacity of the battery pack. When the uninterruptible power supply is connected with a plurality of loads, the back-filling energy of each load may be different, and at this time, the back-filling energy value corresponding to the load with the maximum required electric energy may be selected as the single energy back-filling maximum value of the load corresponding to the uninterruptible power supply. The larger the maximum value of the single energy of the load is, which indicates that the more the single energy of the load is, the more the spare capacity of the battery pack needs to be maintained, that is, the first set value needs to be in a negative correlation with the maximum value of the single energy of the load. The larger the battery capacity of the battery pack is, the more the total electric quantity that can be accommodated by the battery pack is, and the larger the first setting value can be, that is, the first setting value has a positive correlation with the battery capacity of the battery pack.

In this embodiment of the present application, the power supply state of the power grid may be continuously monitored during the period when the power grid keeps normal power supply. When the power supply of the power grid fails, the uninterruptible power supply can continue to supply power to the load by using the electric energy stored in the battery pack. Because the battery pack is adopted to supply power to the load, the electric quantity parameter of the battery pack can be continuously reduced, after the power grid restores normal power supply, the electric quantity parameter of the battery pack can be reduced to be smaller than a first set value, and at the moment, the power grid can charge the battery pack through the charge-discharge module. Specifically, with continued reference to fig. 9, in this embodiment of the present application, the uninterruptible power supply method further includes the following steps:

and S105, controlling the charge-discharge module to charge the battery pack until the electric quantity parameter is equal to the first set value so as to ensure that the battery pack stores sufficient electric energy to continuously supply power to the load after the subsequent power grid fault occurs. The first setting value may be considered as an upper limit of charging of the battery pack by the power grid, that is, the charging and discharging module stops the charging state after the battery pack is charged to the first setting value.

Optionally, in this embodiment of the application, the step S101 of detecting whether there is energy back-flow in the load connected to the uninterruptible power supply in real time may specifically be implemented in the following two ways:

the first method is as follows: detecting whether the output power of an inverter in the uninterruptible power supply is a negative value or not in real time, if the output power of the inverter is a positive value, indicating that the inverter provides electric energy for the load, and if the output power of the inverter is a negative value, indicating that the load provides the electric energy for the inverter, namely determining that the load has energy back-flow.

The second method comprises the following steps: and detecting whether the voltage value of a bus capacitor in the uninterruptible power supply is higher than a second set value in real time, wherein the bus capacitor plays the roles of storing electric energy and stabilizing voltage, the voltage value of the bus capacitor is related to the electric energy provided by the bus, when the uninterruptible power supply is normally powered, the voltage value of the capacitor of the control module is a normal voltage value, and the second set value takes a value between the normal voltage value and a tolerable maximum voltage value. If the voltage value of the bus capacitor is lower than a second set value, the bus normally provides electric energy, and if the voltage value of the bus capacitor is higher than the second set value, the bus energy is overlarge, and the fact that the load has energy reverse flow can be determined.

While the above description has been made in terms of method embodiments, it will be appreciated that, in order to implement the above method, the ups device may include a hardware structure and/or software modules that perform the respective functions. Those of skill in the art would readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed in hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

An embodiment of the present application further provides a power supply system, including: the embodiment of the application provides the uninterruptible power supply and the battery pack connected with the uninterruptible power supply. Since the battery pack may have frequent charging and discharging processes, a battery type suitable for frequent charging and discharging may be generally selected, for example, a battery pack formed by a lithium battery may be selected.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (16)

1. The uninterrupted power supply is characterized by comprising a control module and a charging and discharging module;

the charging and discharging module is used for connecting a battery pack so as to charge or discharge the connected battery pack;

the control module is used for controlling the charging and discharging module to charge the reversely charged energy to the battery pack when the situation that the load connected with the uninterruptible power supply has the energy reverse charge is determined.

2. The uninterruptible power supply of claim 1, wherein the control module is further configured to control the charge and discharge module to discharge the battery pack until the charge parameter is not greater than a first set value when it is determined that there is no energy back-flow to the load and it is determined that the charge parameter of the battery pack is greater than the first set value.

3. The uninterruptible power supply of claim 1, wherein the control module is further configured to control the charging and discharging module to charge the battery pack until a charge parameter of the battery pack is equal to the first set value.

4. The uninterruptible power supply of claim 2 or 3, wherein the charge parameter comprises:

a state of charge, SOC, of the battery pack, or a battery voltage of the battery pack, or a real-time capacity of the battery pack.

5. The uninterruptible power supply of any of claims 2 to 4, wherein the first set point is negatively correlated to a maximum single energy recharge value of the load, and the first set point is positively correlated to a battery capacity of the battery pack.

6. The uninterruptible power supply of any of claims 1 to 5, further comprising an inverter and a bus capacitor;

the control module is specifically used for determining that the load has energy back-flow when the output power of the inverter is determined to be a negative value; or when the voltage value of the bus capacitor is higher than a second set value, determining that the load has energy back-flowing.

7. The UPS of any one of claims 1-6, wherein a maximum charging power of the charge-discharge module is greater than a maximum energy back-charging power of a load to which the UPS is connected.

8. The uninterruptible power supply of any of claims 1 to 7, wherein the charge and discharge module comprises a charge circuit and a discharge circuit independent of each other, the charge circuit being configured to charge the battery pack and the discharge circuit being configured to discharge the battery pack;

or the charge and discharge module comprises a charge and discharge loop, and the charge and discharge loop is used for charging or discharging the connected battery pack.

9. An uninterruptible power supply method, comprising:

detecting whether energy reverse irrigation exists in a load connected with the uninterruptible power supply in real time;

and when the load is determined to have energy reverse irrigation, controlling a charge-discharge module to charge the energy in the reverse irrigation to a battery pack connected with the uninterruptible power supply.

10. The power supply method of claim 9, further comprising:

when the load is determined not to have energy back-flow, and when the electric quantity parameter of the battery pack is larger than a first set value, the charging and discharging module is controlled to discharge the battery pack until the electric quantity parameter is not larger than the first set value.

11. The power supply method of claim 9, further comprising:

and controlling the charging and discharging module to charge the battery pack until the electric quantity parameter of the battery pack is equal to the first set value.

12. The power supply method according to claim 10 or 11, wherein the charge parameter comprises a state of charge (SOC) of the battery pack, or a battery voltage of the battery pack, or a real-time capacity of the battery pack.

13. The power supply method according to any one of claims 10 to 12, wherein the first set value and the maximum value of the single energy recharge of the load are in a negative correlation, and the first set value and the battery capacity of the battery pack are in a positive correlation.

14. The power supply method according to any one of claims 9-13, wherein the detecting in real time whether there is energy back-filling in the load to which the ups is connected comprises:

when the output power of an inverter in the uninterruptible power supply is detected to be a negative value, determining that the load has energy backward flow; or the like, or, alternatively,

and when the voltage value of a bus capacitor in the uninterruptible power supply is detected to be higher than a second set value, determining that the load has energy reverse flow.

15. The power supply method according to any one of claims 9-14, wherein the maximum charging power of the charging and discharging module is greater than the maximum energy back-flowing power of a load connected with the ups.

16. A power supply system, comprising: the uninterruptible power supply of any of claims 1 to 8, and a battery pack connected to the uninterruptible power supply.

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