Charging and discharging circuit and uninterruptible power supply

Abstract

The invention provides a charging and discharging circuit and an uninterruptible power supply, and relates to the technical field of power electronics, the uninterruptible power supply comprises a rectification circuit, an inversion circuit, a charging and discharging circuit, a positive bus and a negative bus, the input end of the rectification circuit is used for connecting an AC power supply, and the output end of the rectification circuit is connected with the input end of the inversion circuit through the positive bus and the negative bus; the input end of the charging and discharging circuit is used for connecting an energy storage device, and the output end is connected with the positive bus and the negative bus. The charging and discharging circuit is used for charging and discharging the energy storage device. When the absolute value of the voltage difference between the positive bus and the negative bus is larger than or equal to a first threshold value, the voltage difference between the positive bus and the negative bus is adjusted to be smaller than the first threshold value by controlling the switch action in the charging and discharging circuit so as to balance the voltages of the positive bus and the negative bus. The charging and discharging circuit is multiplexed to adjust the voltage balance of the positive and negative buses, the circuit design is simplified, and the space utilization rate of the uninterruptible power supply is improved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a charge and discharge circuit and an uninterruptible power supply. Background Art

[0002] An uninterruptible power supply (UPS) is a system that can provide uninterrupted power supply for electronic devices. An energy storage device is provided inside the UPS. When the mains power is normal, the UPS converts the mains voltage into the supply voltage for the load and supplies the supply voltage to the load for use. When the mains power fails, the voltage stored in the energy storage device is converted into the supply voltage and supplied to the load for use, thereby ensuring power supply reliability.

[0003] The UPS mainly includes a rectifier circuit, a positive bus, a negative bus, a DC / AC inverter circuit, and a DC / DC charge and discharge circuit. When the mains power supplies power, the rectifier circuit performs power conversion on the received electric energy and outputs it to the positive bus and the negative bus. When the energy storage device supplies power, the DC / DC charge and discharge circuit converts the direct current output by the energy storage device and then outputs it to the positive bus and the negative bus. The inverter circuit converts the direct current on the positive bus and the negative bus into alternating current and then outputs it to the load to supply power to the load, thereby improving the efficiency of the UPS. In practice, there may be an unbalanced phenomenon between the positive and negative buses due to different power demands of the load on the electric energy. A balance circuit needs to be set in the UPS to achieve power regulation between the positive bus and the negative bus. Moreover, the DC / DC charge and discharge circuit is always in a working state in the energy storage device power supply mode. The power of the DC / DC charge and discharge circuit needs to meet the rated power of the UPS system, and the required circuit volume is relatively large, resulting in disadvantages in cost and space. Summary of the Invention

[0004] The present application provides an uninterruptible power supply, which combines the DC / DC charge and discharge circuit and the balance circuit into one, reduces the circuit volume, and improves the space utilization rate of the uninterruptible power supply.

[0005] In a first aspect, the present application provides an uninterruptible power supply, comprising: a rectifier circuit, an inverter circuit, a charge and discharge circuit, a positive bus and a negative bus. The input end of the rectifier circuit is used to connect to an AC power supply, and the output end of the rectifier circuit is connected to the input end of the inverter circuit through the positive bus and the negative bus. The input end of the charge and discharge circuit is used to connect to an energy storage device, and the output end of the charge and discharge circuit is connected to the positive bus and the negative bus. When the AC power supply supplies power to the load, the rectifier circuit is used to receive the first alternating current output by the AC power supply and convert the first alternating current into the first direct current and output it to the inverter circuit, and the inverter circuit is used to convert the first direct current into the second alternating current and output it to the load. When the energy storage device supplies power to the load, the charge and discharge circuit is used to receive the second direct current output by the energy storage device and convert the second direct current into the third direct current and output it to the inverter circuit, and the inverter circuit is used to convert the third direct current into the third alternating current and output it to the load. When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the charge and discharge circuit is used to control the switch in the charge and discharge circuit to act to adjust the voltage difference between the positive bus and the negative bus to be less than the first threshold. When the voltages of the positive and negative buses are unbalanced, by controlling the switch in the charge and discharge circuit to act to achieve voltage regulation of the positive and negative buses, so as to achieve the balance of the voltages of the positive and negative buses, which simplifies the circuit design and improves the space utilization rate of the uninterruptible power supply.

[0006] In a possible implementation, when the energy storage device receives electrical energy from the AC power supply, the charge and discharge circuit is used to receive the first direct current output by the rectifier circuit through the positive bus and the negative bus and convert the first direct current into the fourth direct current and output it to the energy storage device. When the AC power supply is normal, the energy storage device can be powered by the AC power supply so that the energy storage device can supply power to the load through the charge and discharge circuit and the inverter circuit when the AC power supply fails.

[0007] In a possible implementation, the charge and discharge circuit includes a positive bus capacitor and a negative bus capacitor, a first inductor, a second inductor, a first diode, a second diode, a first switching switch, a second switching switch, a first switching transistor, a second switching transistor, and a third switching transistor. The circuit formed by the series connection of the positive bus capacitor and the negative bus capacitor is connected in parallel with the circuit formed by the series connection of the first switching transistor, the second switching transistor, and the third switching transistor. The input end of the charge and discharge circuit includes a positive input end and a negative input end. The positive input end is connected to the connection point of the first switching transistor and the second switching transistor through the first switching switch and the first inductor, and the negative input end is connected to the connection point of the second switching transistor and the third switching transistor through the second switching switch and the second inductor. The first diode and the second diode are connected in series. The negative electrode of the first diode is connected to the connection point of the first switching switch and the first inductor, and the positive electrode of the second diode is connected to the connection point of the second switching switch and the second inductor. The balance circuit multiplexes the charge and discharge circuit, and the circuit structure design is simple. During the charge and discharge process of the energy storage device, the charge and discharge circuit plays a role in power conversion. When the positive and negative bus voltages are unbalanced, the charge and discharge circuit can play a role in balancing the voltage, saving the volume of the uninterruptible power supply and improving the space utilization rate.

[0008] In a possible implementation, when the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the first switching switch and the second switching switch are turned off. At this time, the charge and discharge circuit operates in a balanced state. Further, when the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to the second threshold, at this time the voltage of the positive bus is too high, the first switching transistor and the second switching transistor act synchronously, and the third switching transistor does not act. The electric energy in the positive bus is released to the second inductor, thereby reducing the voltage difference between the positive bus voltage and the negative bus voltage. And / or, when the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the third threshold, at this time the voltage of the negative bus is too high, the second switching transistor and the third switching transistor act synchronously, and the first switching transistor does not act. The electric energy in the negative bus is released to the first inductor, thereby reducing the voltage difference between the negative bus voltage and the positive bus voltage.

[0009] In a possible implementation, the charge and discharge circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switching switch, a second switching switch, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, and a fifth switching transistor. The circuit formed by the series connection of the first capacitor and the second capacitor is connected in parallel with the circuit formed by the series connection of the first switching transistor, the second switching transistor, and the third switching transistor. The input end of the charge and discharge circuit includes a positive input end and a negative input end. The positive input end is connected to the connection point between the first switching transistor and the second switching transistor through the first switching switch and the first inductor, and the negative input end is connected to the connection point between the second switching transistor and the third switching transistor through the second switching switch and the second inductor. The fourth switching transistor and the fifth switching transistor are connected in series between the connection point of the first switching switch and the first inductor and the connection point of the second switching switch and the second inductor. The balance circuit multiplexes the charge and discharge circuit. The circuit structure design is simple. During the charge and discharge process of the energy storage device, the charge and discharge circuit plays a role in power conversion. When the positive and negative bus voltages are unbalanced, the charge and discharge circuit can play a role in balancing the voltage, saving the volume of the uninterruptible power supply and improving the space utilization rate.

[0010] In a possible implementation, when the energy storage device receives electrical energy from an AC power source, the first switching switch and the second switching switch are turned on, the first switching transistor and the third switching transistor act synchronously, the second switching transistor does not act, and the charge and discharge circuit is in the charging state. The energy storage device receives electrical energy from the AC power source through the rectifier circuit and the charge and discharge circuit. And / or, when the energy storage device supplies power to a load, the first switching switch and the second switching switch are turned on, the second switching transistor acts, the first switching transistor and the third switching transistor do not act, and the charge and discharge circuit is in the discharging state. The energy storage device supplies electrical energy to the load through the charge and discharge circuit and the inverter circuit.

[0011] In a possible implementation, a third diode is connected in parallel across the two ends of the first switching switch. The positive electrode of the third diode is connected to the connection point of the first switching switch and the first inductor, and a fourth diode is connected in parallel across the two ends of the second switching switch. The negative electrode of the fourth diode is connected to the connection point of the second switching switch and the second inductor. By utilizing the unidirectional conduction performance of the diode, it is possible to prevent the charge and discharge circuit from back-feeding the bus due to excessive current in the energy storage device during the charging state, improving the safety of the circuit.

[0012] In a possible implementation, the first switching switch and the second switching switch are switching devices including body diodes. For example, they can be MOS transistors or other equivalent switching devices. Even if the first switching switch and the second switching switch do not perform switching actions, the circuit can be conducted through the internal body diodes.

[0013] In a possible implementation, when the energy storage device receives electrical energy from an AC power source, the charge-discharge circuit is in a charging state, the first switching switch and the second switching switch are disconnected, the first switching transistor and the third switching transistor act synchronously, and the second switching transistor does not act. When the charge-discharge circuit is in the charging state and the first switching switch and the second switching switch are in a stable disconnected state, the energy storage device can be charged through the third diode and the fourth diode. Due to the unidirectional conduction property of the diode, if a battery failure causes the voltage of the energy storage device to be higher than the bus voltage, the diode can prevent current from flowing back to the bus, improving the safety of the circuit. And / or, when the energy storage device supplies power to a load, the charge-discharge circuit is in a discharging state, the first switching switch and the second switching switch are conducting, the second switching transistor acts, and the first switching transistor and the third switching transistor do not act. The energy storage device supplies electrical energy to the load through the charge-discharge circuit and the inverter circuit.

[0014] In a possible implementation, when the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the first switching switch and the second switching switch are disconnected, and the charge-discharge circuit operates in a balanced state. When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to the second threshold, at this time the voltage of the positive bus is too high, the first switching transistor, the second switching transistor and the fifth switching transistor act synchronously, and the third switching transistor and the fourth switching transistor do not act. The electrical energy in the positive bus is released to the second inductor, thereby reducing the voltage difference between the positive bus and the negative bus and making the voltages of the positive and negative buses balanced. When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the third threshold, at this time the voltage of the negative bus is too high, the second switching transistor, the third switching transistor and the fourth switching transistor act synchronously, and the first switching transistor and the fifth switching transistor do not act. The electrical energy in the negative bus is released to the first inductor, thereby reducing the voltage difference between the positive bus and the negative bus and making the voltages of the positive and negative buses balanced.

[0015] In a possible implementation, when the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the first switching switch and the second switching switch are disconnected, and the charge-discharge circuit operates in a balanced state. When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to the second threshold, at this time the voltage of the positive bus is too high, the first switching transistor and the second switching transistor act synchronously, the fifth switching switch is conducting, and the third switching transistor and the fourth switching transistor do not act. The electrical energy in the positive bus is released to the second inductor, reducing the voltage difference between the positive and negative buses. And / or, when the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, at this time the voltage of the negative bus is too high, the second switching transistor and the third switching transistor act synchronously, the fourth switching switch is conducting, and the first switching transistor and the fifth switching transistor do not act. The electrical energy in the negative bus is released to the first inductor, thereby reducing the voltage difference between the negative bus and the positive bus and making the voltages of the positive and negative buses balanced.

[0016] In a possible implementation, when the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the first switching switch and the second switching switch are turned off. When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to the second threshold, the voltage of the positive bus is too high, and the first switching transistor and the second switching transistor act synchronously, while the third switching transistor, the fourth switching transistor, and the fifth switching transistor do not act. The electric energy in the positive bus is released to the second inductor, reducing the voltage difference between the positive and negative buses. And / or, when the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, the voltage of the negative bus is high, and the second switching transistor and the third switching transistor act synchronously, while the first switching transistor, the fourth switching transistor, and the fifth switching transistor do not act. The electric energy in the negative bus is released to the first inductor, thereby reducing the voltage difference between the negative bus voltage and the positive bus voltage and making the voltages of the positive and negative buses balanced.

[0017] In a possible implementation, when the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to the first threshold, the first switching switch and the second switching switch are turned off. When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to the second threshold, the first switching transistor acts, and the second switching transistor, the fourth switching transistor, and the fifth switching transistor are turned on, while the third switching transistor does not act. The electric energy in the positive bus is released to the first inductor and the second inductor, thereby reducing the voltage difference between the positive bus voltage and the negative bus voltage and making the voltages of the positive and negative buses balanced. And / or, when the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, the voltage of the negative bus is too high, the third switching transistor acts, and the second switching transistor, the fourth switching transistor, and the fifth switching transistor are turned on, while the first switching transistor does not act. The electric energy in the negative bus is released to the first inductor and the second inductor, thereby reducing the voltage difference between the negative bus voltage and the positive bus voltage and making the voltages of the positive and negative buses balanced.

[0018] In a possible implementation, a first fuse and a second fuse are connected in series between the first diode and the second diode. When the current of the charge and discharge circuit is too large, the fuse melts due to excessive temperature, thereby cutting off the circuit and stopping the operation of the charge and discharge circuit, improving the safety of the circuit.

[0019] In a possible implementation, a third fuse is provided between the first switching switch and the positive input terminal, and a fourth fuse is provided between the second switching switch and the negative input terminal. Or, a third fuse is provided between the first switching switch and the first inductor, and a fourth fuse is provided between the second switching switch and the second inductor. When the current of the charge and discharge circuit is too large, the fuse melts due to excessive temperature, thereby cutting off the circuit and stopping the operation of the charge and discharge circuit, improving the safety of the circuit.

[0020] In a possible implementation, a first Hall element is provided between the first switching switch and the first inductor, and a second Hall element is provided between the second switching switch and the second inductor. The first Hall element and the second Hall element can detect current. When an abnormal current (such as an excessive current or a reverse current, etc.) appears in the circuit, the charge and discharge circuit is cut off in time, so that the charge and discharge circuit stops working, ensuring the safety of the circuit.

[0021] In a second aspect, the present application provides a charge and discharge circuit. The input end of the charge and discharge circuit is used to connect to an energy storage device, and the output end of the charge and discharge circuit is used to connect to a positive bus and a negative bus. The charge and discharge circuit includes a positive bus capacitor and a negative bus capacitor, a first inductor, a second inductor, a first diode, a second diode, a first switching switch, a second switching switch, a first switching tube, a second switching tube, and a third switching tube. The circuit formed by the series connection of the positive bus capacitor and the negative bus capacitor is connected in parallel with the circuit formed by the series connection of the first switching tube, the second switching tube, and the third switching tube. The input end of the charge and discharge circuit includes a positive input end and a negative input end. The positive input end is connected to the connection point of the first switching tube and the second switching tube through the first switching switch and the first inductor, and the negative input end is connected to the connection point of the second switching tube and the third switching tube through the second switching switch and the second inductor. The first diode and the second diode are connected in series. The negative electrode of the first diode is connected to the connection point of the first switching switch and the first inductor, and the positive electrode of the second diode is connected to the connection point of the second switching switch and the second inductor.

[0022] In a third aspect, an embodiment of the present application provides a charge and discharge circuit. The input end of the charge and discharge circuit is used to connect to an energy storage device, and the output end of the charge and discharge circuit is used to connect to a positive bus and a negative bus. The charge and discharge circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switching switch, a second switching switch, a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, and a fifth switching tube. The circuit formed by the series connection of the first capacitor and the second capacitor is connected in parallel with the circuit formed by the series connection of the first switching tube, the second switching tube, and the third switching tube. The input end of the charge and discharge circuit includes a positive input end and a negative input end. The positive input end is connected to the connection point of the first switching tube and the second switching tube through the first switching switch and the first inductor, and the negative input end is connected to the connection point of the second switching tube and the third switching tube through the second switching switch and the second inductor. The fourth switching tube and the fifth switching tube are connected in series between the connection point of the first switching switch and the first inductor and the connection point of the second switching switch and the second inductor. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of an uninterruptible power supply in the prior art;

[0024] Figure 2 is a schematic structural diagram of an uninterruptible power supply provided by an embodiment of the present application;

[0025] Figure 3 is a schematic structural diagram of the charge and discharge circuit provided by an embodiment of the present application;

[0026] Figures 3a to 3h is a schematic diagram of the working principle of the charge and discharge circuit provided by an embodiment of the present application under different conditions;

[0027] Figure 4 is a schematic diagram of the first working state of various switches in the charge and discharge circuit provided by an embodiment of the present application;

[0028] Figures 5 to 7 is a schematic structural diagram of the charge and discharge circuit provided by an embodiment of the present application;

[0029] Figures 6a to 6d is in an embodiment of the present application Figure 6 schematic diagram of the working principle of the provided charge and discharge circuit under different conditions;

[0030] Figures 7a to 7l is in an embodiment of the present application Figure 7 schematic diagram of the working principle of the provided charge and discharge circuit under different conditions;

[0031] Figure 8 is a schematic diagram of the second working state of various switches in the charge and discharge circuit provided by an embodiment of the present application;

[0032] Figure 9 is a schematic diagram of the third working state of various switches in the charge and discharge circuit provided by an embodiment of the present application;

[0033] Figure 10 is a schematic diagram of the fourth working state of various switches in the charge and discharge circuit provided by an embodiment of the present application;

[0034] Figure 11 is a schematic diagram of the fifth working state of various switches in the charge and discharge circuit provided by an embodiment of the present application;

[0035] Figures 12 to 14 are three other schematic structural diagrams of the charge and discharge circuit provided by an embodiment of the present application. Detailed implementation manners

[0036] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0037] Figure 1Fig. 0 shows a schematic structural diagram of a UPS provided by the prior art. The AC power supply 100 can be the commercial power. When the commercial power is normal, the UPS converts the voltage of the commercial power into the supply voltage for the load 400 and supplies the supply voltage to the load 400 for use. When the commercial power fails, the voltage stored in the energy storage device 300 is converted into the supply voltage and supplied to the load 400 for use, so as to ensure the power supply reliability. The UPS mainly includes a rectifier circuit 220, a positive bus Bar +, a negative bus Bar -, a DC / AC inverter circuit 230 and a DC / DC charge and discharge circuit 240. A switching circuit 210 can also be provided between the rectifier circuit 220 and the AC power supply 100, and the switching circuit 210 can control the AC power supply 100 to supply power to the rectifier circuit 220. When the commercial power supplies power to the load, the rectifier circuit 220 converts the received commercial power into direct current and outputs it to the positive bus Bar + and the negative bus Bar -. When the commercial power fails, the energy storage device 300 supplies power to the load. The DC / DC charge and discharge circuit 240 converts the direct current output by the energy storage device 300 and then outputs it to the positive bus Bar + and the negative bus Bar -. The DC / AC inverter circuit 230 converts the direct current on the positive bus Bar + and the negative bus Bar - into alternating current and then outputs it to the load 400 to supply power to the load 400, thereby improving the efficiency of the UPS. In practice, there may be an unbalanced phenomenon between the positive and negative buses because the load 400 has different demands for electric energy. A balancing circuit needs to be set in the UPS to realize the voltage regulation between the positive bus Bar + and the negative bus Bar -. Moreover, the DC / DC charge and discharge circuit 240 is always in the working state in the power supply mode of the energy storage device 300. The power of the DC / DC charge and discharge circuit 240 needs to meet the rated power of the UPS system, and the required circuit volume is relatively large, bringing disadvantages in cost and space.

[0038] In another example, the switching circuit 210 can also control the energy storage device 300 to supply power to the rectifier circuit 220. The rectifier circuit 220 and the energy storage device 300 are connected through the switching circuit 210. The rectifier circuit 220 converts the voltage of the direct current output by the energy storage device 300 and then outputs it to the inverter circuit 230. The inverter circuit 230 converts the direct current output by the rectifier circuit 220 into alternating current and outputs it to the load 400.

[0039] Figure 2FIG. 0 shows a schematic structural diagram of a UPS200 provided by an embodiment of the present application. In the embodiment of the present application, the charge and discharge circuit 260 and the balancing circuit are combined into one to reduce the design of circuit components and improve the utilization rate of the circuit. The UPS200 includes a rectifier circuit 220, an inverter circuit 230, a charge and discharge circuit 260, a positive bus Bus+ and a negative bus Bus-. A switching circuit 210 is provided between the rectifier circuit 220 and the AC power supply 100. The A-phase input terminal, B-phase input terminal, and C-phase input terminal of the rectifier circuit 220 are respectively used to connect the three-phase output terminals of the AC power supply 100, and the AC power supply 100 can be a commercial power supply. The output terminal of the rectifier circuit 220 is connected to the input terminal of the inverter circuit 230 through the positive bus Bus+ and the negative bus Bus-. The UPS200 further includes bus capacitors C1 and C2. The input terminal of the charge and discharge circuit 260 is connected to the energy storage device 300, and the output terminal of the charge and discharge circuit 260 is connected to the positive bus Bus+ and the negative bus Bus-. When the AC power supply 100 supplies power to the load 400, the rectifier circuit 220 receives the first alternating current output by the AC power supply 100 and converts the first alternating current into the first direct current and outputs it to the inverter circuit 230. The inverter circuit 230 converts the first direct current into the second alternating current and outputs it to the load 400. When the AC power supply 100 fails and cannot supply power to the load 400, the energy storage device 300 supplies power to the load 400. The charge and discharge circuit 260 receives the second direct current output by the energy storage device 300 and converts the second direct current into the third direct current and outputs it to the inverter circuit 230. The inverter circuit 230 converts the third direct current into the third alternating current and outputs it to supply power to the load 400. During the operation of the UPS200, there may be a situation where the voltages of the positive bus Bus+ and the negative bus Bus- are unbalanced. When the absolute value of the voltage difference between the positive bus Bus+ and the negative bus Bus- is greater than or equal to the first threshold, the charge and discharge circuit 260 can control the switch state in the charge and discharge circuit 260 to adjust the voltage difference between the positive bus Bus+ and the negative bus Bus- to be less than the first threshold, so as to balance the positive and negative bus voltages.

[0040] Exemplarily, the AC power supply 100 can also charge the energy storage device 300. When the energy storage device 300 receives the electric energy of the AC power supply 100, the rectifier circuit 220 converts the alternating current output by the AC power supply 100 into the first direct current and outputs it to the positive bus Bus+ and the negative bus Bus-. The charge and discharge circuit 260 receives the first direct current output by the rectifier circuit 220 through the positive bus Bus+ and the negative bus Bus- and converts the first direct current into the fourth direct current and outputs it to the energy storage device 300 to achieve charging of the energy storage device 300.

[0041] Specifically, referring to Figure 3Schematic diagram of the circuit topology of the charge and discharge circuit 260 shown. The charge and discharge circuit 260 includes a positive bus capacitor C3 and a negative bus capacitor C4, a first inductor L1, a second inductor L2, a first diode D1, a second diode D2, a first switching switch R1, a second switching switch R2, a first switching transistor Q1, a second switching transistor Q2, and a third switching transistor Q3. The circuit formed by the series connection of the positive bus capacitor C3 and the negative bus capacitor C4 is connected in parallel with the circuit formed by the series connection of the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3. The input end of the charge and discharge circuit 260 includes a positive input end Bat+ and a negative input end Bat-. The positive input end Bat+ is connected to the connection point of the first switching transistor Q1 and the second switching transistor Q2 through the first switching switch R1 and the first inductor L1. The negative input end Bat- is connected to the connection point of the second switching transistor Q2 and the third switching transistor Q3 through the second switching switch R2 and the second inductor L2. The first diode D1 and the second diode D2 are connected in series. The negative electrode of the first diode D1 is connected to the connection point of the first switching switch R1 and the first inductor L1. The positive electrode of the second diode D2 is connected to the connection point of the second switching switch R2 and the second inductor L2.

[0042] When the charge and discharge circuit 260 is used for the charge and discharge of the energy storage device 300, that is, when the energy storage device 300 supplies power to the load 400 or when the energy storage device 300 receives the AC power supply 100, the first switching switch R1 and the second switching switch R2 are turned on. During the charging process, the first switching transistor Q1 and the third switching transistor Q3 act synchronously, and the second switching transistor Q2 does not act. During the discharging process, the first switching transistor Q1 and the third switching transistor Q3 do not act, and the second switching transistor Q2 acts. In the embodiments of the present application, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 are taken as switching transistors including body diodes as an example. For example, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 are MOS transistors.

[0043] It should be noted that the "synchronous action of the switching transistors" involved in the embodiments of the present application refers to "synchronous conduction of the switching transistors or synchronous turn-off of the switching transistors". The "non-action of the switching transistors" involved in this article means "not adjusting the duty cycle of the switching transistors". The embodiments of the present application adjust the action of the switching transistors by adjusting the duty cycle of the switching transistors [conduction time / (conduction time + turn-off time)].

[0044] Specifically, when the commercial power is normal, the energy storage device 300 receives the electric energy of the AC power supply 100 through the rectifier circuit 220 and the charge and discharge circuit 260. The charge and discharge circuit 260 operates in the charging state, and the charge and discharge circuit 260 includes two working stages:

[0045] (1) The first stage: The first switching transistor Q1 and the third switching transistor Q3 are turned on synchronously, the second switching transistor Q2 is stably turned off, and the positive and negative busbars charge the first inductor L1 and the second inductor L2. For the circuit operating state, refer to Figure 3a , Figure 3a The arrow direction in which indicates the current flow direction.

[0046] (2) The second stage: The first switching transistor Q1 and the third switching transistor Q3 are turned off synchronously, and the body diode in the second switching transistor Q2 conducts. The electrical energy stored in the first inductor L1 and the second inductor L2 is used to charge the energy storage device 300. The current direction can be referred to Figure 3b as shown.

[0047] Figure 4 is Figure 3 a schematic diagram of the operating states of the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the switching process of the charge and discharge circuit 260 shown. The actions of each switching transistor can be controlled by adjusting the duty cycle of each switching transistor. During the charging process, the states of each switch can be referred to Figure 4 the operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period from t0 to t1 or from t7 to t8 in

[0048] When the mains power is abnormal, the energy storage device 300 supplies power to the load 400, and the charge and discharge circuit 260 operates in the discharge state. The first switching switch R1 and the second switching switch R2 are stably turned on. The charge and discharge circuit 260 includes two operating stages:

[0049] (1) The first stage: The first switching transistor Q1 and the third switching transistor Q3 are turned off synchronously, and the second switching transistor Q2 is turned on. For the circuit operating state at this time, refer to Figure 3c , Figure 3c The arrow direction in which indicates the current flow direction. At this time, the energy storage device 300 stores energy in the first inductor L1 and the second inductor L2.

[0050] (2) The second stage: The first switching transistor Q1 and the third switching transistor Q3 are turned on synchronously, and the second switching transistor Q2 is turned off. At this time, the first inductor L1 and the second inductor L2 discharge to the positive busbar Bus+ voltage and the negative busbar Bus-. The current direction can be referred to Figure 3d as shown.

[0051] During the discharge process, the states of each switch can be referred to Figure 4 the operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period from t1 to t2 or from t9 to t10 in

[0052] When the voltages of the positive and negative busbars are unbalanced, when the charge-discharge circuit 260 is used to balance the voltages of the positive busbar Bus+ and the negative busbar Bus-, the charge-discharge circuit 260 operates in a balanced state. At this time, the energy storage device 300 stops charging and discharging, and the first switching switch R1 and the second switching switch R2 are stably disconnected. Since the voltage of the negative busbar Bus- collected in practice may be negative. Therefore, in the embodiments of the present application, the difference between the absolute values of the voltages of the positive busbar Bus+ and the negative busbar Bus- is used as the judgment basis, and there are the following three cases for the difference between the absolute values of the positive and negative busbar voltages:

[0053] Case 1: When the difference between the absolute value of the voltage of the positive busbar Bus+ and the absolute value of the voltage of the negative busbar Bus- is greater than or equal to the second threshold, at this time, the voltage of the positive busbar Bus+ is too high, the charge-discharge circuit 260 operates in a balanced state, the first switching transistor Q1 and the second switching transistor Q2 act synchronously, and the third switching transistor Q3 does not act, including two working stages:

[0054] (1) The first stage: The first switching transistor Q1 and the second switching transistor Q2 are synchronously turned on, and the third switching transistor Q3 is turned off. The electric energy in the positive busbar Bus+ is released to the second inductor L2. At this time, the working state of the circuit can be seen in Figure 3e , Figure 3e The arrow direction in is the current direction.

[0055] (2) The second stage: The first switching transistor Q1 and the second switching transistor Q2 are turned off, the body diode of the third switching transistor Q3 is turned on, and the electric energy stored in the second inductor L2 is released to the negative busbar capacitor C4. At this time, the working state of the circuit can be seen in Figure 3f , Figure 3f The arrow direction in is the current direction.

[0056] After the above two working stages, the electric energy of the positive busbar Bus+ can be released, so that the voltage difference between the positive busbar Bus+ and the negative busbar Bus- is reduced. The working states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2 and the third switching transistor Q3 during the time period t3 to t4 in can be seen in Figure 4 .

[0057] Case 2: When the difference between the absolute value of the voltage of the negative busbar Bus- and the absolute value of the voltage of the positive busbar Bus+ is greater than or equal to the third threshold, at this time, the voltage of the negative busbar Bus- is too high. At this time, the voltage of the negative busbar Bus- is too high, the charge-discharge circuit 260 operates in a balanced state, the second switching transistor Q2 and the third switching transistor Q3 act synchronously, and the first switching transistor Q1 does not act, including two working stages:

[0058] (1) First stage: The second switching transistor Q2 and the third switching transistor Q3 conduct synchronously, and the first switching transistor Q1 is turned off. Electrical energy in the negative bus Bar- is stored in the first inductor L1, thereby reducing the voltage difference between the positive bus Bar+ and the negative bus Bar-. The working state of the circuit at this time is shown in Figure 3g , Figure 3g The arrow direction in which is the current direction.

[0059] (2) Second stage: The body diode of the first switching transistor Q1 conducts, and the second switching transistor Q2 and the third switching transistor Q3 are turned off. The electrical energy stored in the first inductor L1 is released to the positive bus capacitor C3. The working state of the circuit at this time is shown in Figure 3h , Figure 3h The arrow direction in which is the current direction.

[0060] Through the above two working stages, the electrical energy of the negative bus Bar- can be released, thereby reducing the voltage difference between the positive bus Bar+ and the negative bus Bar-. The states of each switch can be seen in Figure 4 the working states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period t5 to t6 in.

[0061] Case 3: When the difference between the absolute value of the voltage of the negative bus Bar- and the absolute value of the voltage of the positive bus Bar+ is less than the first threshold, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 do not act (turn off), or the first switching transistor Q1 and the third switching transistor Q3 do not act (turn off), and the second switching transistor Q2 conducts. At this time, the charge and discharge circuit 260 does not work. The states of each switch can be seen in Figure 4 the working states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period t4 to t5 in.

[0062] It should be noted that the above-mentioned first threshold, second threshold, and third threshold can be designed and selected by those skilled in the art according to actual needs.

[0063] It should be understood that the first switching switch R1 and the second switching switch R2 are relays, MOS transistors, IGBT transistors, or other switching devices including body diodes. MOS transistors can achieve faster switching and avoid arcing generated during relay switching. For details, see Figure 5 and Figure 6 .

[0064] Take Figure 6For example, a third diode D3 is connected in parallel across both ends of the first switching switch R1. The positive electrode of the third diode D3 is connected to the connection point between the first switching switch R1 and the first inductor L1. A fourth diode D4 is connected in parallel across both ends of the second switching switch R2. The negative electrode of the fourth diode D4 is connected to the connection point between the second switching switch R2 and the second inductor L2.

[0065] When the charge-discharge circuit 260 is in the charging state, the first switching switch R1 and the second switching switch R2 are in a stable off state. The energy storage device 300 can be charged through the third diode D3 and the fourth diode D4. Since the diode has the property of unidirectional conduction, if a battery failure causes the voltage of the energy storage device 300 to be higher than the bus voltage, the diode can prevent current from flowing back to the bus, improving the safety of the circuit.

[0066] When the mains power is normal, the energy storage device 300 receives electrical energy from the AC power supply 100 through the rectifier circuit 220 and the charge-discharge circuit 260. The charge-discharge circuit 260 operates in the charging state. The first switching switch R1 and the second switching switch R2 are turned off. The first switching transistor Q1 and the third switching transistor Q3 act synchronously, and the second switching transistor Q2 does not act. The charge-discharge circuit 260 includes two working stages:

[0067] (1) The first stage: The first switching transistor Q1 and the third switching transistor Q3 are turned on synchronously, and the second switching transistor Q2 is stably turned off. The positive and negative buses charge the first inductor L1 and the second inductor L2. For the working state of the circuit at this time, refer to Figure 6a , Figure 6a The arrow direction in which is the current flow direction.

[0068] (2) The second stage: The first switching transistor Q1 and the third switching transistor Q3 are turned off synchronously, and the body diode of the second switching transistor Q2 conducts. At this time, the electrical energy stored in the first inductor L1 and the second inductor L2 charges the energy storage device 300. The working state of the circuit and the current direction can be referred to Figure 6b shown.

[0069] When the mains power is abnormal, the energy storage device 300 supplies power to the load 400. The charge-discharge circuit 260 operates in the discharging state. The first switching switch R1 and the second switching switch R2 are stably turned on. The first switching transistor Q1 and the third switching transistor Q3 do not act, and the second switching transistor Q2 acts. The charge-discharge circuit 260 includes two working stages:

[0070] (1) The first stage: The first switching transistor Q1 and the third switching transistor Q3 are turned off synchronously, and the second switching transistor Q2 is turned on. At this time, the energy storage device 300 discharges to the first inductor L1 and the second inductor L2. For the working state of the circuit at this time, refer to Figure 6c , Figure 6c The arrow direction in which is the current flow direction.

[0071] (2) Second stage: When the body diodes of the first switching transistor Q1 and the third switching transistor Q3 are conducting and the second switching transistor Q2 is off, at this time, the first inductor L1 and the second inductor L2 discharge to the positive bus Bar + voltage and the negative bus Bar-. The current direction can be referred to Figure 6d as shown.

[0072] The first diode and the second diode in the above embodiments can also be replaced with switching transistors including body diodes, for example Figure 7 as shown. Figure 7 Another circuit topology provided by the embodiment of the present application. The charge and discharge circuit 260 includes a positive bus capacitor C3, a negative bus capacitor C4, a first inductor L1, a second inductor L2, a first switching switch R1, a second switching switch R2, a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, a fourth switching transistor Q4, and a fifth switching transistor Q5. The circuit formed by the series connection of the positive bus capacitor C3 and the negative bus capacitor C4 is connected in parallel with the circuit formed by the series connection of the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3. The input end of the charge and discharge circuit 260 includes a positive input end Bat + and a negative input end Bat-. The positive input end Bat + is connected to the connection point of the first switching transistor Q1 and the second switching transistor Q2 through the first switching switch R1 and the first inductor L1. The negative input end Bat- is connected to the connection point of the second switching transistor Q2 and the third switching transistor Q3 through the second switching switch R2 and the second inductor L2. The fourth switching transistor Q4 and the fifth switching transistor Q5 are connected in series between the connection point of the first switching switch R1 and the first inductor L1 and the connection point of the second switching switch R2 and the second inductor L2.

[0073] In the embodiment of the present application, the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 can be switching devices including body diodes, such as MOS transistors. Even if no wave is sent to the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5, the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 can also achieve automatic unidirectional conduction through the body diodes they contain. It should be noted that the first switching switch R1 and the second switching switch R2 in the embodiment of the present application can also be switching devices including body diodes, or switching devices formed by a relay in parallel with a diode and their equivalent switching devices.

[0074] When the mains power is normal, the energy storage device 300 receives the electrical energy of the AC power supply 100 through the rectifier circuit 220, and the charge and discharge circuit 260 operates in the charging state. The first switching switch R1 and the second switching switch R2 are conducting, the first switching transistor Q1 and the third switching transistor Q3 act synchronously, and the second switching transistor Q2 does not act. The charge and discharge circuit 260 includes two working stages:

[0075] (1) First stage: The first switching transistor Q1 and the third switching transistor Q3 conduct synchronously, and the second switching transistor Q2 is stably off. The positive and negative busbars charge the first inductor L1 and the second inductor L2. The working state of the circuit at this time can be seen in Figure 7a , Figure 7a The arrow direction in

[0076] (2) Second stage: The first switching transistor Q1 and the third switching transistor Q3 turn off synchronously, and the body diode of the second switching transistor Q2 conducts. At this time, the electrical energy stored in the first inductor L1 and the second inductor L2 is used to charge the energy storage device 300. The working state of the circuit and the current direction can be referred to Figure 7b as shown.

[0077] The states of each switch can be seen in Figures 8 to 11 the working states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period from t0 to t1 or from t7 to t8 in

[0078] When the mains power is abnormal, the energy storage device 300 supplies power to the load 400, and the charge-discharge circuit 260 operates in the discharge state. The first switching transistor Q1 and the third switching transistor Q3 do not act, and the second switching transistor Q2 acts. The charge-discharge circuit 260 includes two working stages:

[0079] (1) First stage: The first switching transistor Q1 and the third switching transistor Q3 turn off synchronously, and the second switching transistor Q2 conducts. At this time, the energy storage device 300 discharges to the first inductor L1 and the second inductor L2. The working state of the circuit at this time can be seen in Figure 7c , Figure 7c The arrow direction in

[0080] (2) Second stage: When the body diodes of the first switching transistor Q1 and the third switching transistor Q3 conduct and the second switching transistor Q2 turns off, at this time, the first inductor L1 and the second inductor L2 discharge to the positive busbar Bus+ voltage and the negative busbar Bus-. The current direction can be referred to Figure 7d as shown.

[0081] The states of each switch can be seen in Figures 8 to 11 the working states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period from t1 to t2 or from t9 to t10 in

[0082] When the voltages of the positive and negative busbars are unbalanced, when the charge and discharge circuit 260 is used to balance the voltages of the positive busbar Bus+ and the negative busbar Bus-, the charge and discharge circuit 260 operates in a balanced state. At this time, the energy storage device 300 stops charging and discharging, and the first switching switch R1 and the second switching switch R2 are disconnected. Since the voltage of the negative busbar Bus- collected in practice may be negative. Therefore, in the embodiments of the present application, the difference between the absolute values of the voltages of the positive busbar Bus+ and the negative busbar Bus- is used as the judgment basis, and there are the following three cases for the difference between the absolute values of the positive and negative busbar voltages:

[0083] Case 1: When the difference between the absolute value of the voltage of the positive busbar Bus+ and the absolute value of the voltage of the negative busbar Bus- is greater than or equal to the second threshold, at this time, the voltage of the positive busbar Bus+ is too high, and the charge and discharge circuit 260 operates in a balanced state. In this case, there are various control methods for the switching tubes:

[0084] Control method (1): The first switching tube Q1, the second switching tube Q2, and the fifth switching tube Q5 act synchronously, and the third switching tube Q3 and the fourth switching tube Q4 do not act.

[0085] The first stage: Control the first switching tube Q1, the second switching tube Q2, and the fifth switching tube Q5 to conduct synchronously, and the third switching tube Q3 and the fourth switching tube Q4 are disconnected. For the working state of the circuit at this time, see Figure 7e , Figure 7e . The arrow direction in it is the current direction, and the electric energy in the positive busbar Bus+ is stored in the second inductor L2.

[0086] The second stage: Control the first switching tube Q1 and the second switching tube Q2 to disconnect synchronously, and the body diodes of the third switching tube Q3 and the fifth switching tube Q5 conduct. The electric energy stored in the second inductor L2 is released to the negative busbar capacitor C4. For the working state of the circuit at this time, see Figure 7f , Figure 7f . The arrow direction in it is the current direction.

[0087] The above two working stages reduce the voltage difference between the positive busbar Bus+ and the negative busbar Bus-, and balance the voltages of the positive and negative busbars. The states of each switch can be seen in Figure 8 . For the working states of the first switching switch R1, the second switching switch R2, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, the fourth switching tube Q4, and the fifth switching tube Q5 during the time period from t3 to t4.

[0088] Control method (2): Control the first switching tube Q1 and the second switching tube Q2 to act synchronously, the fifth switching tube Q5 conducts, and the third switching tube Q3 and the fourth switching tube Q4 do not act.

[0089] The first stage: Control the first switch tube Q1 and the second switch tube Q2 to conduct synchronously, keep the fifth switch tube Q5 always on, and turn off the third switch tube Q3 and the fourth switch tube Q4. For the working state of the circuit at this time, please refer to Figure 7e , Figure 7e . The arrow direction in Figure 7e is the current direction, and the electrical energy in the positive bus Bar+ is stored in the second inductor L2.

[0090] The second stage: Control the first switch tube Q1 and the second switch tube Q2 to turn off synchronously, the body diode of the third switch tube Q3 conducts, keep the fifth switch tube Q5 always on, and turn off the fourth switch tube Q4. The electrical energy stored in the second inductor L2 is released to the negative bus capacitor C4. For the working state of the circuit at this time, please refer to Figure 7f , Figure 7f . The arrow direction in Figure 7f is the current direction.

[0091] The above two working stages reduce the voltage difference between the positive bus Bar+ and the negative bus Bar-, making the voltages of the positive and negative buses balanced. For the states of each switch, please refer to Figure 9 the working states of the first switching switch R1, the second switching switch R2, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5 during the time period from t3 to t4 in Figure 9 .

[0092] Control method (3): The first switch tube Q1 and the second switch tube Q2 act synchronously, and the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5 do not act.

[0093] The first stage: The first switch tube Q1 and the second switch tube Q2 conduct synchronously, the body diode of the fifth switch tube Q5 conducts, and the third switch tube Q3 and the fourth switch tube Q4 are turned off. For the working state of the circuit at this time, please refer to Figure 7e , Figure 7e . The arrow direction in Figure 7e is the current direction, and the electrical energy in the positive bus Bar+ is stored in the second inductor L2.

[0094] The second stage: The body diodes of the third switch tube Q3 and the fifth switch tube Q5 conduct, and the first switch tube Q1, the second switch tube Q2, and the fourth switch tube Q4 are turned off. The electrical energy stored in the second inductor L2 is released to the negative bus capacitor C4. For the working state of the circuit at this time, please refer to Figure 7f , Figure 7f . The arrow direction in Figure 7f is the current direction.

[0095] The above two working stages reduce the voltage difference between the positive bus Bar+ and the negative bus Bar-, making the voltages of the positive and negative buses balanced. For the states of each switch, please refer to Figure 10The operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 during the time period from t3 to t4.

[0096] Case 2: When the difference between the absolute value of the voltage of the negative bus Bar- and the absolute value of the voltage of the positive bus Bar+ is greater than or equal to the third threshold, at this time, the voltage of the negative bus Bar- is too high, and the charge and discharge circuit 260 operates in an equilibrium state. In this case, there are multiple control methods for the switching transistors:

[0097] Control method (1): Control the second switching transistor Q2, the third switching transistor Q3, and the fourth switching transistor Q4 to act synchronously, and the first switching transistor Q1 and the fifth switching transistor Q5 do not act.

[0098] The first stage: Control the second switching transistor Q2, the third switching transistor Q3, and the fourth switching transistor Q4 to conduct synchronously, and the first switching transistor Q1 and the fifth switching transistor Q5 are turned off. The operating state of the circuit at this time is shown in Figure 7g , the arrow direction in the figure is the current direction, and the electric energy in the negative bus Bar- is stored in the first inductor L1.

[0099] The second stage: Control the second switching transistor Q2 and the third switching transistor Q3 to turn off synchronously. At this time, the body diodes of the first switching transistor Q1 and the fourth switching transistor Q4 conduct. The electric energy stored in the first inductor L1 is released to the positive bus capacitor C3. The operating state of the circuit at this time is shown in Figure 7h , Figure 7h , the arrow direction in the figure is the current direction.

[0100] Through the above two operating stages, the voltage difference between the positive bus Bar+ and the negative bus Bar- is reduced, so that the voltages of the positive and negative buses are balanced. The states of each switch can be seen in Figure 8 the operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 during the time period from t5 to t6 in

[0101] Control method (2): Control the second switching transistor Q2 and the third switching transistor Q3 to act synchronously, the fourth switching transistor Q4 is conducting, and the first switching transistor Q1 and the fifth switching transistor Q5 do not act.

[0102] The first stage: Control the second switching transistor Q2 and the third switching transistor Q3 to conduct synchronously, the fourth switching transistor Q4 is always on, and the first switching transistor Q1 and the fifth switching transistor Q5 are turned off. The operating state of the circuit at this time is shown in Figure 7g , the arrow direction in the figure is the current direction, and the electric energy in the negative bus Bar- is stored in the first inductor L1.

[0103] The second stage: control the second switch tube Q2 and the third switch tube Q3 to turn off synchronously. At this time, the body diode of the first switch tube Q1 conducts, and the fourth switch tube Q4 is always on. The electric energy stored in the first inductor L1 is released to the positive bus capacitor C3. For the working state of the circuit at this time, refer to Figure 7h , Figure 7h where the arrow direction in

[0104] is the current direction. Through the above two working stages, the voltage difference between the positive bus Bus+ and the negative bus Bus- is reduced, so that the voltages of the positive and negative buses are balanced. The working states of the first switching switch R1, the second switching switch R2, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5 during the time period t5 - t6 in Figure 9 can be referred to.

[0105] Control method (3): control the second switch tube Q2 and the third switch tube Q3 to act synchronously, and the first switch tube Q1, the fourth switch tube Q4, and the fifth switch tube Q5 are turned off.

[0106] The first stage: the second switch tube Q2 and the third switch tube Q3 conduct synchronously, the body diode of the fourth switch tube Q4 conducts, and the first switch tube Q1 and the fifth switch tube Q5 are turned off. For the working state of the circuit at this time, see Figure 7g , where the arrow direction in the figure is the current direction, and the electric energy in the negative bus Bus- is stored in the first inductor L1.

[0107] The second stage: the body diodes of the first switch tube Q1 and the fourth switch tube Q4 conduct, and the second switch tube Q2, the third switch tube Q3, and the fifth switch tube Q5 are turned off. The electric energy stored in the first inductor L1 is released to the positive bus capacitor C3. For the working state of the circuit at this time, refer to Figure 7h , Figure 7h where the arrow direction in

[0108] is the current direction. Through the above two working stages, the voltage difference between the positive bus Bus+ and the negative bus Bus- is reduced, so that the voltages of the positive and negative buses are balanced. The working states of the first switching switch R1, the second switching switch R2, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5 during the time period t5 - t6 in Figure 10 can be referred to.

[0109] Case 3: When the absolute value of the voltage difference between the negative bus Bus- and the positive bus Bus+ is less than the first threshold value, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, and the fifth switch tube Q5 do not act (turn off). At this time, the charge and discharge circuit 260 does not work. The working states of each switch can be referred to Figures 8 to 11The operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 during the time period from t3 to t4. Alternatively, when the difference between the absolute value of the voltage of the negative bus Bar- and the absolute value of the voltage of the positive bus Bar+ is less than the first threshold, the first switching transistor Q1 and the third switching transistor Q3 are turned off, and the second switching transistor Q2, the fourth switching transistor Q4, and the fifth switching transistor Q5 can also be in a constantly conducting state. At this time, the charge and discharge circuit 260 does not operate.

[0110] Based on Figure 7 the circuit topology diagram shown, when the charge and discharge circuit 260 is in an equilibrium state, there is another example of controlling the conduction or disconnection of the switching transistors.

[0111] Case 1: When the difference between the absolute value of the voltage of the positive bus Bar+ and the absolute value of the voltage of the negative bus Bar- is greater than or equal to the second threshold, at this time, the voltage of the positive bus Bar+ is too high, the first switching transistor Q1 operates, the second switching transistor Q2, the fourth switching transistor Q4, and the fifth switching transistor Q5 are turned on, and the third switching transistor Q3 does not operate. The charge and discharge circuit 260 operates in an equilibrium state, including two working stages:

[0112] (1) The first stage: The first switching transistor Q1 is turned on, the second switching transistor Q2, the fourth switching transistor Q4, and the fifth switching transistor Q5 are constantly conducting, and the third switching transistor Q3 is turned off. For the operating state of the circuit at this time, refer to Figure 7i , the arrow direction in the figure is the current direction, and the electrical energy in the positive bus Bar+ is stored in the first inductor L1 and the second inductor L2 respectively;

[0113] (2) The second stage: The first switching transistor Q1 is turned off, the body diode of the third switching transistor Q3 conducts, the second switching transistor Q2, the fourth switching transistor Q4, and the fifth switching transistor Q5 are constantly conducting, and the electrical energy stored in the first inductor L1 and the second inductor L2 is released to the negative bus capacitor C4. For the operating state of the circuit at this time, refer to Figure 7j , Figure 7j where the arrow direction is the current direction.

[0114] The above two working stages reduce the voltage difference between the positive bus Bar+ and the negative bus Bar-, making the voltages of the positive and negative buses balanced. In this case, the states of each switch can be referred to Figure 11 for the operating states of the first switching switch R1, the second switching switch R2, the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 during the time period from t3 to t4.

[0115] Case 2: When the difference between the absolute value of the voltage of the negative bus Bar- and the absolute value of the voltage of the positive bus Bar+ is greater than or equal to the third threshold, the voltage of the negative bus Bar- is too high at this time, and the charge and discharge circuit 260 operates in a balanced state. The third switch Q3 operates, the second switch Q2, the fourth switch Q4, and the fifth switch Q5 are turned on, and the first switch Q1 does not operate, including two working stages:

[0116] (1) The first stage: The third switch Q3 is turned on, the second switch Q2, the fourth switch Q4, and the fifth switch Q5 are always on, and the first switch Q1 is turned off. The working state of the circuit at this time is shown in Figure 7k , the arrow direction in the figure is the current direction, and the electric energy in the negative bus Bar- is stored in the first inductor L1 and the second inductor L2 respectively;

[0117] (2) The second stage: The second switch Q2, the fourth switch Q4, and the fifth switch Q5 are always on, the body diode of the first switch Q1 is turned on, the third switch Q3 is turned off, and the electric energy stored in the first inductor L1 and the second inductor L2 is released to the positive bus capacitor C3. The working state of the circuit at this time is shown in Figure 7l , Figure 7l The arrow direction in is the current direction.

[0118] Through the above two working stages, the voltage difference between the positive bus Bar+ and the negative bus Bar- is reduced, so that the voltages of the positive and negative buses are balanced. In this case, the states of each switch can be seen in Figure 11 the working states of the first switching switch R1, the second switching switch R2, the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the fifth switch Q5 during the time period t5-t6 in.

[0119] Case 3: When the difference between the absolute value of the voltage of the negative bus Bar- and the absolute value of the voltage of the positive bus Bar+ is less than the first threshold, the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the fifth switch Q5 do not operate (turn off). Or the second switch Q2, the fourth switch Q4, and the fifth switch Q5 maintain the always-on state. At this time, the charge and discharge circuit 260 does not work. The states of each switch can be seen in Figure 11 the working states of the first switching switch R1, the second switching switch R2, the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the fifth switch Q5 during the time period t4-t5 in.

[0120] Continue to refer to Figure 14Schematic diagram of the charge and discharge circuit 260 shown. To further enhance the safety of the charge and discharge circuit 260, a fuse 6 and a fuse 7 are connected in series between the first diode D1 and the second diode D2. A fuse 3 can be connected in series between the connection point of the first diode D1 and the second diode D2 and the neutral line. When the current in the charge and discharge circuit 260 is too large, the fuse 6 and the fuse 7 will melt due to excessive temperature, thus cutting off the circuit and making the charge and discharge circuit 260 stop working, improving the safety of the circuit.

[0121] Referring to Figure 13 Schematic diagram of the charge and discharge circuit 260 shown. A fuse 4 is provided between the first switching switch R1 and the positive input terminal Bat+. A fuse 5 is provided between the second switching switch R2 and the negative input terminal Bat-.

[0122] Referring to Figure 14 Schematic diagram of the charge and discharge circuit 260 shown. A fuse 2 is provided between the first switching switch R1 and the first inductor L1. A fuse 2 is provided between the second switching switch R2 and the second inductor L2. The fuse 1 and the fuse 2 can melt in time to cut off the circuit when the current is too large, making the charge and discharge circuit 260 stop working and ensuring the safety of the circuit.

[0123] It should be noted that the fuse mentioned in this application can be devices such as fuses and air switches commonly used in daily life.

[0124] Referring to Figures 12 to 14 As shown, a first Hall element CT1 can be provided between the first switching switch R1 and the first inductor L1, and a second Hall element CT2 can be provided between the second switching switch R2 and the second inductor L2. The first Hall element CT1 and the second Hall element CT2 can be ammeters for detecting current. When an abnormal current (such as excessive current or reverse current) appears in the circuit, the charge and discharge circuit 260 is cut off in time to make the charge and discharge circuit 260 stop working and ensure the safety of the circuit.

[0125] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An uninterruptible power supply, characterized in that: include: A rectifier circuit, an inverter circuit, a charge-discharge circuit, a positive bus and a negative bus, wherein the input end of the rectifier circuit is used to connect to an AC power source, the output end of the rectifier circuit is connected to the input end of the inverter circuit through the positive bus and the negative bus, the input end of the charge-discharge circuit is used to connect to an energy storage device, and the output end of the charge-discharge circuit is connected to the positive bus and the negative bus; When the AC power supply supplies power to the load, the rectifier circuit is used to receive the first AC power output by the AC power supply and convert the first AC power into a first DC power and output it to the inverter circuit, and the inverter circuit is used to convert the first DC power into a second AC power and output it to the load; When the energy storage device supplies power to the load, the charging and discharging circuit is used to receive the second direct current output by the energy storage device and convert the second direct current into a third direct current and output it to the inverter circuit, and the inverter circuit is used to convert the third direct current into a third alternating current and output it to the load; When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the charge and discharge circuit is used to control the switch action in the charge and discharge circuit to adjust the voltage difference between the positive bus and the negative bus to be less than the first threshold.

2. The uninterruptible power supply according to claim 1, characterized in that: When the energy storage device receives electric energy from the AC power supply, the charging and discharging circuit is used to receive the first DC power output by the rectifier circuit through the positive bus and the negative bus and convert the first DC power into a fourth DC power and output it to the energy storage device.

3. The uninterruptible power supply according to claim 1 or 2, characterized in that: The charging and discharging circuit includes a positive bus capacitor and a negative bus capacitor, a first inductor, a second inductor, a first diode, a second diode, a first switching switch, a second switching switch, a first switching tube, a second switching tube and a third switching tube; The circuit formed by the series connection of the positive bus capacitor and the negative bus capacitor is connected in parallel with the circuit formed by the series connection of the first switch tube, the second switch tube and the third switch tube; The input end of the charge and discharge circuit includes a positive input end and a negative input end, the positive input end is connected to a connection point between the first switch tube and the second switch tube through a first switch and the first inductor, and the negative input end is connected to a connection point between the second switch tube and the third switch tube through a second switch and the second inductor; The first diode and the second diode are connected in series, the cathode of the first diode is connected to a connection point between the first switching switch and the first inductor, and the anode of the second diode is connected to a connection point between the second switching switch and the second inductor.

4. The uninterruptible power supply according to claim 3, characterized in that: When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the first switch and the second switch are disconnected; When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to a second threshold, the first switch tube and the second switch tube are synchronously operated, and the third switch tube is not operated; and / or, When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the third threshold, the second switch tube and the third switch tube act synchronously, and the first switch tube does not act.

5. The uninterruptible power supply according to claim 1 or 2, characterized in that: The charging and discharging circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switch, a second switch, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a fifth switch tube; A circuit formed by connecting the first capacitor and the second capacitor in series is connected in parallel with a circuit formed by connecting the first switch tube, the second switch tube and the third switch tube in series; The input end of the charge and discharge circuit includes a positive input end and a negative input end, the positive input end is connected to a connection point between the first switch tube and the second switch tube through a first switch and the first inductor, and the negative input end is connected to a connection point between the second switch tube and the third switch tube through a second switch and the second inductor; The fourth switch tube and the fifth switch tube are connected in series between a connection point between the first switch and the first inductor and a connection point between the second switch and the second inductor.

6. The uninterruptible power supply according to any one of claims 1 to 5, characterized in that: When the energy storage device receives electric energy from the AC power source, the first switch and the second switch are turned on, the first switch tube and the third switch tube are synchronously actuated, and the second switch tube is inactive; and / or, When the energy storage device supplies power to the load, the first switch and the second switch are turned on, the first switch tube and the third switch tube are not in operation, and the second switch tube is in operation.

7. The uninterruptible power supply according to any one of claims 1 to 5, characterized in that: A third diode is connected in parallel at both ends of the first switching switch, and the anode of the third diode is connected to the connection point between the first switching switch and the first inductor. A fourth diode is connected in parallel at both ends of the second switching switch, and the cathode of the fourth diode is connected to the connection point between the second switching switch and the second inductor.

8. The uninterruptible power supply according to any one of claims 1 to 5, characterized in that: The first switch and the second switch are switch devices including body diodes.

9. The uninterruptible power supply according to claim 7 or 8, characterized in that: When the energy storage device receives electric energy from the AC power source, the first switch and the second switch are disconnected, the first switch tube and the third switch tube are synchronously actuated, and the second switch tube is inactive; And / or, when the energy storage device supplies power to the load, the first switch and the second switch are turned on, the second switch tube is in operation, and the first switch tube and the third switch tube are inoperable.

10. The uninterruptible power supply according to claim 5 or 6, characterized in that: When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the first switch and the second switch are disconnected; When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to a second threshold, the first switch tube, the second switch tube and the fifth switch tube are synchronously operated, and the third switch tube and the fourth switch tube are not operated; and / or, When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the third threshold, the second switch tube, the third switch tube and the fourth switch tube act synchronously, and the first switch tube and the fifth switch tube do not act.

11. The uninterruptible power supply according to claim 5 or 6, characterized in that: When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the first switch and the second switch are disconnected; When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to a second threshold, the first switch tube and the second switch tube are synchronously actuated, the fifth switch tube is turned on, and the third switch tube and the fourth switch tube are not actuated; and / or, When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, the second switch tube and the third switch tube act synchronously, the fourth switch tube is turned on, and the first switch tube and the fifth switch tube do not act.

12. The uninterruptible power supply according to claim 5 or 6, characterized in that: When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the first switch and the second switch are disconnected; When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to a second threshold, the first switch tube and the second switch tube are synchronously operated, and the third switch tube, the fourth switch tube and the fifth switch tube are not operated; and / or, When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, the second switch tube and the third switch tube act synchronously, and the first switch tube, the fourth switch tube and the fifth switch tube do not act.

13. The uninterruptible power supply according to claim 5 or 6, characterized in that: When the absolute value of the voltage difference between the positive bus and the negative bus is greater than or equal to a first threshold, the first switch and the second switch are disconnected; When the difference between the absolute value of the voltage of the positive bus and the absolute value of the voltage of the negative bus is greater than or equal to a second threshold, the first switch tube is actuated, the second switch tube, the fourth switch tube, and the fifth switch tube are turned on, and the third switch tube is not actuated; and / or, When the difference between the absolute value of the voltage of the negative bus and the absolute value of the voltage of the positive bus is greater than or equal to the second threshold, the third switch tube is activated, the second switch tube, the fourth switch tube and the fifth switch tube are turned on, and the first switch tube is not activated.

14. The uninterruptible power supply according to any one of claims 1 to 4, characterized in that: A first fuse and a second fuse are connected in series between the first diode and the second diode.

15. The uninterruptible power supply according to any one of claims 1 to 14, characterized in that: A third fuse is provided between the first switching switch and the positive input terminal, and a fourth fuse is provided between the second switching switch and the negative input terminal; or a third fuse is provided between the first switching switch and the first inductor, and a fourth fuse is provided between the second switching switch and the second inductor.

16. A charging and discharging circuit, characterized in that: The input end of the charging and discharging circuit is used to connect the energy storage device, and the output end of the charging and discharging circuit is used to connect the positive bus and the negative bus. The charging and discharging circuit includes a positive bus capacitor and a negative bus capacitor, a first inductor, a second inductor, a first diode, a second diode, a first switching switch, a second switching switch, a first switch tube, a second switch tube and a third switch tube; The circuit formed by the series connection of the positive bus capacitor and the negative bus capacitor is connected in parallel with the circuit formed by the series connection of the first switch tube, the second switch tube and the third switch tube; The input end of the charge and discharge circuit includes a positive input end and a negative input end, the positive input end is connected to a connection point between the first switch tube and the second switch tube through a first switch and the first inductor, and the negative input end is connected to a connection point between the second switch tube and the third switch tube through a second switch and the second inductor; The first diode and the second diode are connected in series, the cathode of the first diode is connected to a connection point between the first switching switch and the first inductor, and the anode of the second diode is connected to a connection point between the second switching switch and the second inductor.

17. A charging and discharging circuit, characterized in that: The input end of the charge and discharge circuit is used to connect the energy storage device, the output end of the charge and discharge circuit is used to connect the positive bus and the negative bus, and the charge and discharge circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switch, a second switch, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and a fifth switch tube; A circuit formed by connecting the first capacitor and the second capacitor in series is connected in parallel with a circuit formed by connecting the first switch tube, the second switch tube and the third switch tube in series; The input end of the charge and discharge circuit includes a positive input end and a negative input end, the positive input end is connected to a connection point between the first switch tube and the second switch tube through a first switch and the first inductor, and the negative input end is connected to a connection point between the second switch tube and the third switch tube through a second switch and the second inductor; The fourth switch tube and the fifth switch tube are connected in series between a connection point between the first switch and the first inductor and a connection point between the second switch and the second inductor.

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