Online uninterruptible power supply

Abstract

The application discloses an online uninterruptible power supply and relates to the technical field of power supply. The online uninterruptible power supply provided by the embodiment of the application can bidirectionally transmit electric energy, improve the utilization rate of components in the circuit, reduce the cost, and charge a direct-current power supply with a lower secondary winding voltage, and prevent low-frequency current from flowing into the secondary winding in the charging mode by adding a first selection circuit, a first inductance filter circuit and two first unidirectional conduction circuits on the primary winding side and adding two first switch circuits, a second selection circuit and a direct-current isolation circuit on the secondary winding side.

Description

Online uninterruptible power supply Technical Field

[0001] This application belongs to the field of power supply technology, and in particular relates to an online uninterruptible power supply. Background Technology

[0002] Online uninterruptible power supplies (UPS) convert the direct current (DC) from a rechargeable battery to alternating current (AC), which is then rectified and filtered to obtain the voltage required by the load, thus enabling the battery to discharge. When charging the rechargeable battery, a separate charging circuit is needed to convert the input voltage to the required voltage for high-power charging. Because two separate circuits operate independently to perform the charging and discharging processes, the utilization rate of components in online UPSs is low, resulting in a larger number of components and higher overall cost. Summary of the Invention

[0003] This application provides an online uninterruptible power supply (UPS) designed to address the problem of low component utilization in traditional online UPS systems.

[0004] This application provides an online uninterruptible power supply, including:

[0005] The push-pull circuit is configured such that its two ends are connected to the two ends of the primary winding of the transformer, and its common terminal is connected to the negative terminal of the DC power supply.

[0006] In the DC power supply discharge mode, the first selection circuit is configured to control the positive terminal of the DC power supply to connect to the tap of the primary winding, and in the DC power supply charging mode, control the positive terminal of the DC power supply to connect to one end of the first inductor filter circuit, the other end of the first inductor filter circuit to connect to the cathodes of two first unidirectional conduction circuits, and the anodes of the two first unidirectional conduction circuits to connect to the two ends of the primary winding respectively.

[0007] The first full-bridge rectifier circuit includes a first bridge arm and a second bridge arm connected in parallel. The midpoint of the first bridge arm is connected to the same-name terminal of the secondary winding of the transformer. The tap of the secondary winding is also connected to the common output terminal of the power factor correction circuit. The input terminal of the power factor correction circuit is connected to the power supply.

[0008] The second selection circuit is used to control the opposite end of the secondary winding to connect to the midpoint of the second bridge arm in the discharge mode, and to connect one end of the DC blocking circuit in the charging mode.

[0009] Two first switching circuits are configured such that one is connected in series between the first bus output terminal of the power factor correction circuit and the other end of the DC blocking circuit, and the other is connected in series between the other end of the DC blocking circuit and the second bus output terminal of the power factor correction circuit;

[0010] Two second inductor filter circuits are configured such that one is connected in series between the cathode of the second bridge arm and the output terminal of the first bus, and the other is connected in series between the anode of the second bridge arm and the output terminal of the second bus.

[0011] The half-bridge inverter circuit is configured to connect the power factor correction circuit at its input and the load at its output.

[0012] Optionally, the DC blocking circuit includes:

[0013] A first capacitor, the two ends of which are respectively connected to the second selection circuit and the other end of the first switching circuit, is used to prevent low-frequency current from passing through the secondary winding in the charging mode.

[0014] Optionally, the first unidirectional conduction circuit includes a diode;

[0015] One of the diodes in the first unidirectional conduction circuit is connected in series between the other end of the first inductor filter circuit and the same-named end of the primary winding; and / or, another diode in the first unidirectional conduction circuit is connected in series between the other end of the first inductor filter circuit and the opposite-named end of the primary winding.

[0016] Optionally, the first inductor filter circuit includes:

[0017] A first inductor, one end of which is connected to the first selection circuit and the other end of which is connected to the cathodes of the two first unidirectional conduction circuits, is used to filter the charging current of the DC power supply in the discharge mode.

[0018] Optionally, the online uninterruptible power supply further includes:

[0019] The first filter circuit is connected in series between the positive and negative terminals of the DC power supply.

[0020] Optionally, the power factor correction circuit includes:

[0021] The third inductor filter circuit is connected in series between the first power supply terminal of the power supply and the anode of the second unidirectional conduction circuit. The anode of the second unidirectional conduction circuit is also connected to the cathode of the third unidirectional conduction circuit.

[0022] The second full-bridge rectifier circuit includes a third bridge arm and a fourth bridge arm connected in parallel. The midpoint of the third bridge arm is connected to the anode of the second unidirectional conduction circuit, and the midpoint of the fourth bridge arm is connected to the second power supply terminal of the power supply and the tap of the secondary winding.

[0023] The second switching circuit is connected in series between the cathode and the anode of the second bridge arm;

[0024] The second filter circuit is configured such that one end is the output terminal of the first bus and is connected to the cathode of the second unidirectional conduction circuit, and the other end is the common output terminal and is connected to one end of the third filter circuit and the tap of the secondary winding.

[0025] The third filter circuit is configured such that its other end is the output terminal of the second bus and connected to the anode of the third unidirectional conduction circuit.

[0026] Optionally, the half-bridge inverter circuit includes:

[0027] The first power switch bridge arm is connected in parallel between the first bus output terminal and the second bus output terminal;

[0028] The fourth filter circuit is configured to connect one end to the midpoint of the first power switch bridge arm and the other end to the common output terminal, and the fourth filter circuit is also used to connect the load.

[0029] Optionally, the fourth filter circuit includes:

[0030] The second inductor is configured such that one end is connected to the midpoint of the first power switch bridge arm and the other end is connected to one end of the second capacitor;

[0031] The second capacitor is configured to have one end connected to the common output terminal, and both ends of the second capacitor are also used to connect to the load.

[0032] Optionally, the online uninterruptible power supply further includes:

[0033] The third selection circuit is connected to the input terminal of the power factor correction circuit, the output terminal of the half-bridge inverter circuit, and the load, and is used to control the input terminal of the power factor correction circuit to be connected to the load, or to control the output terminal of the half-bridge inverter circuit to be connected to the load.

[0034] Optionally, the online uninterruptible power supply further includes:

[0035] The fourth switching circuit is connected in series between the power supply and the input terminal of the power factor correction circuit.

[0036] The beneficial effects of the embodiments in this application compared with the prior art are:

[0037] In discharge mode, the positive terminal of the DC power supply (e.g., a rechargeable battery) is connected to the tap of the primary winding, and the opposite terminal of the secondary winding is connected to the midpoint of the second bridge arm. The switches in the push-pull circuit are activated, thus forming a push-pull discharge structure on the DC power supply side. The voltage of the DC power supply is applied to the primary winding through the push-pull circuit to form alternating current and is transmitted to the secondary winding. The two first switching circuits and the power factor correction circuit are not activated, and the half-bridge inverter circuit is activated. The output of the secondary winding is supplied to the half-bridge inverter circuit after passing through the first full-bridge rectifier circuit, the two second inductor filter circuits, the first bus output terminal, the second bus output terminal, and the common output terminal, so that the half-bridge inverter circuit can output the voltage required by the load. In charging mode, the positive terminal of the DC power supply is connected to one end of the first inductor filter circuit, and the opposite terminal of the secondary winding is connected to one end of the DC blocking circuit. The switches in the push-pull circuit are not activated (or are synchronously switched according to the direction of the current to achieve synchronous rectification). The two first switching circuits and the power factor correction circuit are activated to form a half-bridge charging structure, realizing the charging of the DC power supply by the power supply. The online uninterruptible power supply provided in this application embodiment, by adding a first selection circuit, a first inductor filter circuit, and two first unidirectional conduction circuits on the primary winding side, and adding two first switching circuits, a second selection circuit, and a DC blocking circuit on the secondary winding side, enables the online uninterruptible power supply to transmit electrical energy bidirectionally, improves the utilization rate of components in the circuit, reduces costs, and can charge the DC power supply with a lower secondary winding voltage, and prevents low-frequency current from flowing into the secondary winding in charging mode. Attached Figure Description

[0038] Figure 1 is a schematic diagram of the first structure of the online uninterruptible power supply provided in the embodiment of this application;

[0039] Figure 2 is a schematic diagram of a second structure of an online uninterruptible power supply provided in an embodiment of this application;

[0040] Figure 3 is a schematic diagram of the third structure of the online uninterruptible power supply provided in the embodiment of this application.

[0041] Illustration:

[0042] 10. DC power supply; 11. First selection circuit; 12. First inductor filter circuit; 13. First unidirectional conduction circuit; 15. First filter circuit; 16. Push-pull circuit; 17. First full-bridge rectifier circuit; 18. Second inductor filter circuit; 19. First switching circuit; 20. Second selection circuit; 21. DC blocking circuit; 24. Half-bridge inverter circuit; 25. First power switch arm; 26. Fourth filter circuit; 27. Third switching circuit; 28. Third inductor filter circuit; 29. ​​Second full-bridge rectifier circuit; 30. Second switching circuit; 31. Power factor correction circuit; 32. Third selection circuit; L. First power supply terminal; N. Second power supply terminal; BUS+. First bus output terminal; BUS-. Second bus output terminal; T. Transformer; P. Primary winding; S. Secondary winding; C1. First capacitor; C2. Second capacitor; C3. Third capacitor; C4. Fourth capacitor; Capacitor; C5, fifth capacitor; L1, first inductor; L2, second inductor; L3, third inductor; L4, fourth inductor; L5, fifth inductor; Q1, first power switch; D1, first body diode; Q2, second power switch; D2, second body diode; Q3, third power switch; D3, third body diode; Q4, fourth power switch; D4, fourth body diode; Q5, fifth power switch; D5, fifth body diode; Q6, sixth power switch; D6, sixth body diode; Q7, seventh power switch; d1, first diode; d2, second diode; d3, third diode; d4, fourth diode; d5, fifth diode; d6, sixth diode; d7, seventh diode; d8, eighth diode; d9, ninth diode; d10, tenth diode; d11, eleventh diode; d12, twelfth diode. Detailed Implementation

[0043] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0044] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0045] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0047] Online uninterruptible power supplies (UPS) convert the direct current (DC) from a rechargeable battery to alternating current (AC), which is then rectified and filtered to obtain the voltage required by the load, thus enabling the battery to discharge. When charging the rechargeable battery, a separate charging circuit is needed to convert the input voltage to the required voltage for high-power charging. Because two separate circuits operate independently to perform the charging and discharging processes, the utilization rate of components in online UPSs is low, resulting in a larger number of components and higher overall cost.

[0048] In view of this, the present application provides an online uninterruptible power supply (UPS). By adding a selection circuit, an inductor filter circuit, and two unidirectional conduction circuits to the primary winding side of the transformer, and adding two switching circuits, a selection circuit, and a DC blocking circuit to the secondary winding side, this configuration enables bidirectional energy transfer, high-power charging, improves the utilization rate of components in the online UPS, reduces costs, allows charging of DC power with a lower secondary winding voltage, and prevents low-frequency current from flowing into the secondary winding during charging.

[0049] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0050] Figure 1 shows a schematic diagram of the structure of an online uninterruptible power supply provided in an embodiment of this application. For ease of explanation, only the parts related to this embodiment are shown.

[0051] As shown in Figure 1, the online uninterruptible power supply provided in this embodiment includes a transformer T, a push-pull circuit 16, a first selection circuit 11, a first inductor filter circuit 12, two first unidirectional conduction circuits 13 (the first unidirectional conduction circuit 13 on the left and the first unidirectional conduction circuit 13 on the right), a first full-bridge rectifier circuit 17, two second inductor filter circuits 18 (the second inductor filter circuit 18 on the upper side and the second inductor filter circuit 18 on the lower side), two first switching circuits 19 (the first switching circuit 19 on the upper side and the first switching circuit 19 on the lower side), a second selection circuit 20, a DC blocking circuit 21, a half-bridge inverter circuit 24, and a power factor correction circuit 31.

[0052] Among them, the push-pull circuit 16, the first selection circuit 11, the first inductor filter circuit 12, the first unidirectional conduction circuit 13 on the left and the first unidirectional conduction circuit 13 on the right are arranged on the P side of the primary winding of the transformer T. The first full-bridge rectifier circuit 17, the upper second inductor filter circuit 18, the lower second inductor filter circuit 18, the upper first switch circuit 19, the lower first switch circuit 19, the second selection circuit 20, the DC blocking circuit 21, the half-bridge inverter circuit 24 and the power factor correction circuit 31 are arranged on the S side of the secondary winding of the transformer T.

[0053] The two ends of the push-pull circuit 16 are connected to the two ends of the primary winding P, and the common terminal is connected to the negative terminal of the DC power supply 10. The first selection circuit 11 is connected to the positive terminal of the DC power supply 10, the tap of the primary winding P, and one end of the first inductor filter circuit 12. The other end of the first inductor filter circuit 12 is connected to the cathodes of the left and right first unidirectional conduction circuits 13. The anode of the left first unidirectional conduction circuit 13 is connected to the same-name terminal of the primary winding P, and the anode of the right first unidirectional conduction circuit 13 is connected to the opposite-name terminal of the primary winding P.

[0054] In this embodiment, the DC power supply 10 can discharge to the outside and can also charge the DC power supply 10. When the DC power supply 10 is discharging, it is said to be in discharge mode; when the DC power supply 10 is charging, it is said to be in charging mode.

[0055] When the DC power supply 10 is in discharge mode, the first selection circuit 11 connects the positive terminal of the DC power supply 10 to the tap of the primary winding P, thus making the circuit between the positive terminal of the DC power supply 10 and the tap of the primary winding P conductive. In this discharge mode, the push-pull circuit 16 applies the voltage of the DC power supply 10 to the primary winding P in a push-pull manner to form alternating current, which is then transmitted to the secondary winding S.

[0056] When the DC power supply 10 is in charging mode, the first selection circuit 11 connects the positive terminal of the DC power supply 10 to one end of the first inductor filter circuit 12, thus making the circuit between the positive terminal of the DC power supply 10 and one end of the first inductor filter circuit 12 conductive. In this charging mode, the secondary winding S transmits AC current to the primary winding P. This AC current passes through the first unidirectional conduction circuit 13 on the left or right side, and then passes through the first inductor filter circuit 12. The first inductor filter circuit 12 stores energy and charges the DC power supply 10. When the secondary winding S stops transmitting AC current, on the primary winding P side, the first inductor filter circuit 12 uses the stored energy to freewheel the current for current filtering, maintaining the charging current for the DC power supply 10. It should be noted that in charging mode, the switch in the push-pull circuit 16 may not operate, or it may switch synchronously according to the direction of the current to achieve synchronous rectification. This embodiment does not specifically limit this.

[0057] The first full-bridge rectifier circuit 17 includes a first bridge arm and a second bridge arm, which are connected in parallel. The midpoint of the first bridge arm (such as the anode of the third diode d3) is connected to the same-name terminal of the secondary winding S, and the midpoint of the second bridge arm (such as the anode of the fifth diode d5) is connected to the opposite-name terminal of the secondary winding S through the second selection circuit 20.

[0058] The power factor correction circuit 31 is configured to connect its input to a power supply for power factor correction (PFC) of the power supply output and to output DC power. The outputs of the power factor correction circuit 31 include a first bus output terminal (BUS+), a second bus output terminal (BUS-), and a common output terminal. Optionally, the common output terminal is used to connect to the neutral wire of the power supply.

[0059] The first bus output terminal BUS+ is connected to the cathode of the second bridge arm (such as the cathode of the fifth diode d5) through the upper second inductor filter circuit 18. The second bus output terminal BUS- is connected to the anode of the second bridge arm (such as the anode of the sixth diode d6) through the lower second inductor filter circuit 18. The common output terminal is connected to the tap of the secondary winding S.

[0060] Two first switching circuits 19 are provided between the first bus output terminal BUS+ and the second bus output terminal BUS-. One end of the upper first switching circuit 19 is connected to the first bus output terminal BUS+ and the upper second inductor filter circuit 18, and the other end of the upper first switching circuit 19 is connected to one end of the lower first switching circuit 19. The other end of the lower first switching circuit 19 is connected to the second bus output terminal BUS- and the lower second inductor filter circuit 18. A DC blocking circuit 21 is also provided between the second selection circuit 20 and the other end of the upper first switching circuit 19. The second selection circuit 20 is used to control the connection of the DC blocking circuit 21 to the opposite-named terminal of the secondary winding S in charging mode, and to control the connection of the opposite-named terminal of the secondary winding S to the midpoint of the second bridge arm in discharging mode. In charging mode, the two first switching circuits 19 are used to allow the outputs of the first bus output terminal BUS+, the second bus output terminal BUS-, and the common output terminal to be transmitted to the primary winding P through the secondary winding S to charge the DC power supply 10.

[0061] Therefore, when the DC power supply 10 is in discharge mode, the second selection circuit 20 controls the opposite-name terminal of the secondary winding S to connect to the midpoint of the second bridge arm. The voltage across the secondary winding S is rectified by the first full-bridge rectifier circuit 17 and then supplied to the first bus output terminal BUS+, the second bus output terminal BUS-, and the neutral output terminal through the upper second inductor filter circuit 18, the lower second inductor filter circuit 18, and the taps of the secondary winding S. Finally, the first bus output terminal BUS+, the second bus output terminal BUS-, and the common output terminal provide DC voltage to the half-bridge inverter circuit 24, which inverts this DC voltage into AC power required by the load.

[0062] When the DC power supply 10 is in charging mode, the second selection circuit 20 controls the opposite-name terminal of the secondary winding S to connect to one end of the DC blocking circuit 21. Through the upper first switch circuit 19 and the lower first switch circuit 19 set between the first bus output terminal BUS+ and the second bus output terminal BUS-, the DC power output by the power factor correction circuit 31 can be provided to the secondary winding S to form a half-bridge charging architecture, thereby charging the DC power supply 10 and improving the utilization rate of components in the online uninterruptible power supply.

[0063] It should be understood that the DC power output from the power factor correction circuit 31 can also be provided to the half-bridge inverter circuit 24 so as to provide the required power to the load while charging the DC power supply 10.

[0064] Based on the above description, in discharge mode, the first selection circuit 11 controls the positive terminal of the DC power supply 10 to connect to the tap of the primary winding P, and the second selection circuit 20 controls the opposite-named terminal of the secondary winding S to connect to the midpoint of the second bridge arm, so as to form a push-pull discharge structure. In this discharge mode, the upper first switching circuit 19 and the lower first switching circuit 19 are turned off. The voltage output from the secondary winding S is rectified by the first full-bridge rectifier circuit 17, and then passes through the upper second inductor filter circuit 18, the lower second inductor filter circuit 18, the first bus output terminal BUS+, the second bus output terminal BUS-, and the common output terminal to provide AC power to the half-bridge inverter circuit 24. The half-bridge inverter circuit 24 outputs the AC power required by the load. It should be understood that in discharge mode, it is necessary to disconnect the power supply from the power factor correction circuit 31, or the power supply must stop outputting AC power.

[0065] In charging mode, the first selection circuit 11 controls the positive terminal of the DC power supply 10 to connect to one end of the first inductor filter circuit 12, and the second selection circuit 20 controls the opposite end of the secondary winding S to connect to one end of the DC blocking circuit 21. The upper first switching circuit 19 and the lower first switching circuit 19 work to form a half-bridge charging architecture.

[0066] For example, when the AC output from the power supply is in the positive half-cycle, the upper first switching circuit 19 switches at high frequency, and the lower first switching circuit 19 is turned off. When the upper first switching circuit 19 is turned on, the current direction on the secondary winding S side is from the first bus output terminal BUS+, the upper first switching circuit 19, the DC blocking circuit 21, the second selection circuit 20, the opposite-name terminal of the secondary winding S, and the tap of the secondary winding S to the common output terminal. When both the upper and lower first switching circuits 19 are turned off, the current on the primary winding P side is freewheeled through the first inductor filter circuit 12 to filter the current and maintain the charging current for the DC power supply 10.

[0067] For example, when the AC output from the power supply is in the negative half-cycle, the upper first switching circuit 19 is turned off, and the lower first switching circuit 19 switches at high frequency. When the lower first switching circuit 19 is turned on, the current direction on the secondary winding S side is from the primary output terminal, the tap of the secondary winding S, the opposite terminal of the secondary winding S, the second selection circuit 20, the DC blocking circuit 21, the lower first switching circuit 19, to the second bus output terminal BUS-. When both the upper and lower first switching circuits 19 are turned off, the primary winding P side is freewheeled through the first inductor filter circuit 12 to maintain the charging current for the DC power supply 10.

[0068] It should be noted that the online uninterruptible power supply provided in this embodiment can charge the DC power supply 10 with a lower secondary winding voltage by switching the effective value (e.g., number of turns) of the primary winding P through the first selection circuit 11.

[0069] For example, in discharge mode, when the minimum discharge voltage of DC power supply 10 is 40V, to ensure that the output voltage of the half-bridge inverter circuit 24 reaches 230Vac, the voltage between the first bus output terminal BUS+ and the second bus output terminal BUS- needs to be approximately 360Vdc. At this time, the turns ratio of the secondary winding S and the primary winding P of transformer T is 9. In charging mode, the charging voltage of DC power supply 10 is approximately 57.6V. If the effective value of the primary winding P is not changed through the first selection circuit 11, then when the voltage between the first bus output terminal BUS+ and the second bus output terminal BUS- is 360Vdc, the primary winding P receives a voltage of 40V, which is less than the charging voltage of 57.6V, resulting in the inability to charge DC power supply 10. In this embodiment, by switching the effective value of the primary winding P through the first selection circuit 11, the turns ratio between the secondary winding S and the primary winding P can be reduced in the charging mode, for example, reduced to 4.5, so that the primary winding P obtains a voltage of 80V, which is greater than the charging voltage of 57.6V, thereby realizing the charging of the DC power supply 10.

[0070] It should also be noted that, in the charging mode, the current on the secondary winding S side of the online uninterruptible power supply provided in this embodiment needs to pass through the DC blocking circuit 21, which can prevent DC (or low-frequency current) from passing through and improve charging efficiency.

[0071] As shown in Figure 1, as an optional implementation of this embodiment, at least one of the first inductor filter circuit 12, the upper second inductor filter circuit 18, and the lower second inductor filter circuit 18 includes an inductor so as to realize energy storage and freewheeling through the inductor for current filtering.

[0072] For example, the first inductor filter circuit 12 includes a first inductor L1, which is connected in series between the cathode of the first selection circuit 11 and the cathode of the first unidirectional conduction circuit 13 on the left.

[0073] For example, the upper second inductor filter circuit 18 includes a third inductor L3, which is connected in series between the cathode of the second bridge arm and the first bus output terminal BUS+.

[0074] For example, the lower second inductor filter circuit 18 includes a fourth inductor L4, which is connected in series between the anode of the second bridge arm and the second bus output terminal BUS-.

[0075] As shown in Figure 1, in an optional implementation of this embodiment, the first selection circuit 11 includes a first relay unit, which includes a first coil, a first normally open contact, and a first normally closed contact. The first normally open contact and the first normally closed contact have a first common connection terminal, which is connected to the positive terminal of the DC power supply 10. The first normally open contact is connected to one end of the first inductor L1, and the first normally closed contact is connected to a tap of the primary winding P. For example, when the first coil is energized, the first normally open contact closes, and the first normally closed contact opens, meaning the positive terminal of the DC power supply 10 is connected to one end of the first inductor L1; when the first coil is de-energized, the first normally open contact opens, and the first normally closed contact closes, meaning the positive terminal of the DC power supply 10 is connected to a tap of the primary winding P.

[0076] It should be noted that the first selection circuit 11 can also achieve its selection control function through a single-pole double-throw switch or a combination switch with multiple switches. This embodiment does not specifically limit this.

[0077] As shown in Figure 1, in an optional implementation of this embodiment, the push-pull circuit 16 includes a first power switch Q1 and a second power switch Q2. The first power switch Q1 has a first body diode D1, and the second power switch Q2 has a second body diode D2. Optionally, in various embodiments of this application, the power switches can be either metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated-gate bipolar transistors (IGBTs). It should be noted that in various embodiments of this application, the power switches can also be replaced by a switch and a diode connected in parallel.

[0078] For example, the cathodes of the first power switch Q1 and the second power switch Q2 form the two ends of the push-pull circuit 16, and the anodes of the first power switch Q1 and the second power switch Q2 are connected to form the common terminal of the push-pull circuit 16. Specifically, the cathode of the first power switch Q1 is the cathode of the first body diode D1, and the anode of the first power switch Q1 is the anode of the first body diode D1. Similarly, the cathode of the second power switch Q2 is the cathode of the second body diode D2, and the anode of the second power switch Q2 is the anode of the second body diode D2.

[0079] The cathode of the first power switch Q1 is connected to the same-name terminal of the primary winding P, and the cathode of the second power switch Q2 is connected to the opposite-name terminal of the primary winding P. The anodes of both the first power switch Q1 and the second power switch Q2 are connected to the negative terminal of the DC power supply 10. Optionally, the negative terminal of the DC power supply 10 is grounded.

[0080] As shown in Figure 1, in an optional implementation of this embodiment, the first unidirectional conduction circuit 13 on the left includes a first diode d1, and the first unidirectional conduction circuit 13 on the right includes a second diode d2. The cathodes of the first diode d1 and the second diode d2 are connected to the first inductor L1. The anode of the first diode d1 is connected to the same-name terminal of the primary winding P, and the anode of the second diode d2 is connected to the opposite-name terminal of the primary winding P.

[0081] Therefore, in discharge mode, the first power switch Q1 and the second power switch Q2 are turned on alternately, so that the voltage of the DC power supply 10 is input to the primary winding P in a push-pull manner, forming alternating current. In charging mode, when the secondary winding S transmits alternating current to the primary winding P, the current flow direction on the primary winding P side is from the same-name terminal of the primary winding P, the first diode d1, the first inductor L1, the DC power supply 10, and the second body diode D2 (or the second power switch Q2) to the opposite-name terminal of the primary winding P; or, the current flow direction on the primary winding P side is from the opposite-name terminal of the primary winding P, the second diode d2, the first inductor L1, the DC power supply 10, and the first body diode D1 (or the first power switch Q1) to the same-name terminal of the primary winding P. When the secondary winding S stops transmitting AC power to the primary winding P, the first inductor L1 continues to flow on the primary winding P side. The current flows from one end of the first inductor L1, through the DC power supply 10, the first body diode D1 (or the first power switch Q1), and the first diode d1 to the other end of the first inductor L1, and from one end of the first inductor L1, through the DC power supply 10, the second body diode D2 (or the second power switch Q2), and the second diode d2 to the other end of the first inductor L1. When synchronous rectification is required, the first power switch Q1 or the second power switch Q2 is simultaneously turned on, and the current flows through the body of the first power switch Q1 or the second power switch Q2.

[0082] As shown in Figure 1, as an optional implementation of this embodiment, the first full-bridge rectifier circuit 17 includes a third diode d3, a fourth diode d4, a fifth diode d5, and a sixth diode d6. The third diode d3 and the fourth diode d4 are connected in series to form a first bridge arm. The midpoint of the first bridge arm (such as the anode of the third diode d3) is connected to the same-name terminal of the secondary winding S. The fifth diode d5 and the sixth diode d6 are connected in series to form a second bridge arm. The midpoint of the second bridge arm (such as the anode of the fifth diode d5) is connected to the opposite-name terminal of the secondary winding S through the second selection circuit 20.

[0083] As shown in Figure 1, in an optional embodiment of this invention, the upper first switching circuit 19 includes a third power switch Q3, which has a third body diode D3. The lower first switching circuit 19 includes a fourth power switch Q4, which has a fourth body diode D4.

[0084] The cathode of the third power switch Q3 is connected to the third inductor L3 and the first bus output terminal BUS+. The anode of the third power switch Q3 is connected to the cathode of the fourth power switch Q4. The anode of the fourth power switch Q4 is connected to the fourth inductor L4 and the second bus output terminal BUS-.

[0085] As shown in Figure 1, as an optional implementation of this embodiment, the DC blocking circuit 21 includes a first capacitor C1, which is connected in series between the anode of the second selection circuit 20 and the third power switch Q3, and is used to prevent low-frequency current from flowing into the secondary winding S in the charging mode.

[0086] As shown in Figure 1, as an optional implementation of this embodiment, the half-bridge inverter circuit 24 includes a first power switch bridge arm 25 and a fourth filter circuit 26. The first power switch bridge arm 25 is connected in parallel between the first bus output terminal BUS+ and the second bus output terminal BUS-. The fourth filter circuit 26 is connected in series between the midpoint of the first power switch bridge arm 25 and the common output terminal. The fourth filter circuit 26 is also used to connect the load.

[0087] Optionally, the first power switch bridge arm 25 includes a fifth power switch Q5 and a sixth power switch Q6, wherein the fifth power switch Q5 has a fifth body diode D5 and the sixth power switch Q6 has a sixth body diode D6. Optionally, the fourth filter circuit 26 includes a second inductor L2 and a second capacitor C2.

[0088] In this configuration, the cathode of the fifth power switch Q5 is connected to the first bus output terminal BUS+, the anode of the fifth power switch Q5 is connected to one end of the second inductor L2 and the cathode of the sixth power switch Q6, the other end of the second inductor L2 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to the common output terminal, and the anode of the sixth power switch Q6 is connected to the second bus output terminal BUS-. The two ends of the second capacitor C2 are also used to connect the load.

[0089] As shown in Figure 1, as an optional implementation of this embodiment, the power factor correction circuit 31 includes a third inductor filter circuit 28, a second full-bridge rectifier circuit 29, a second switching circuit 30, a third unidirectional conduction circuit, a fourth unidirectional conduction circuit, a second filter circuit, and a third filter circuit.

[0090] Optionally, the third inductor filter circuit 28 includes a fifth inductor L5, the third unidirectional conduction circuit includes a seventh diode d7, the fourth unidirectional conduction circuit includes an eighth diode d8, the second filter circuit includes a third capacitor C3, the third filter circuit includes a fourth capacitor C4, and the second switching circuit 30 includes a seventh power switch Q7.

[0091] Optionally, the second full-bridge rectifier circuit 29 includes four diodes, such as the ninth diode D9, the tenth diode D10, the eleventh diode D11, and the twelfth diode D12. The ninth diode D9 and the tenth diode D10 form the third bridge arm, and the eleventh diode D11 and the twelfth diode D12 form the fourth bridge arm. The third bridge arm and the fourth bridge arm are connected in parallel.

[0092] As an example, one end of the fifth inductor L5 is connected to the first power supply terminal L of the power supply, for example, the first power supply terminal L is the phase line of the mains power. The midpoint of the third bridge arm (such as the anode of the ninth diode d9) is connected to the other end of the fifth inductor L5, and the midpoint of the fourth bridge arm (such as the anode of the eleventh diode d11) is connected to the tap of the second power supply terminal N and the secondary winding S, for example, the second power supply terminal N is the neutral line of the mains power. The seventh power switch Q7 is connected in series between the cathode and anode of the fourth bridge arm. The anode of the seventh diode d7, the cathode of the eighth diode d8, and the other end of the fifth inductor L5 are connected. The cathode of the seventh diode d7, the first end of the third capacitor C3, and the cathode of the third power switch Q3 are connected to form the first bus output terminal BUS+. The anode of the eighth diode d8, the second end of the fourth capacitor C4, and the anode of the fourth power switch Q4 are connected to form the second bus output terminal BUS-. The second terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, the tap of the secondary winding S, and the second power supply terminal N of the power supply are connected to form a common output terminal.

[0093] Therefore, the power factor correction circuit 31 shown in Figure 1 is a boost power factor correction circuit 31, and its working principle is as follows:

[0094] When the AC power output from the power supply is in its positive half-cycle, and the seventh power switch Q7 is turned on, the power supply charges the fifth inductor L5. The current flows from the first power supply terminal L, through the fifth inductor L5, the ninth diode d9, the seventh power switch Q7, and the twelfth diode d12, to the second power supply terminal N. When the seventh power switch Q7 is turned off, the AC power supplied by the power supply, together with the energy stored in the fifth inductor L5, charges the third capacitor C3. The current flows from the first power supply terminal L, through the fifth inductor L5, the seventh diode d7, and the third capacitor C3, to the second power supply terminal N.

[0095] When the AC power output from the power supply is in the negative half-cycle, and the seventh power switch Q7 is turned on, the power supply charges the fifth inductor L5. The current flows from the second power supply terminal N, through the eleventh diode d11, the seventh power switch Q7, and the tenth diode d10 to the first power supply terminal L. When the seventh power switch Q7 is turned off, the AC power supplied by the power supply, together with the energy stored in the fifth inductor L5, charges the fourth capacitor C4. The current flows from the second power supply terminal N, through the fourth capacitor C4, the eighth diode d8, and the fifth inductor L5 to the first power supply terminal L.

[0096] As shown in Figure 2, in another embodiment of this application, the online uninterruptible power supply further includes a first filter circuit 15, which is connected in series between the positive and negative terminals of the DC power supply 10 to stabilize the voltage between the positive and negative terminals of the DC power supply 10. Optionally, the first filter circuit 15 includes a fifth capacitor C5, which is connected in series between the positive and negative terminals of the DC power supply 10.

[0097] As shown in Figure 3, in another embodiment of this application, the online uninterruptible power supply further includes a third switching circuit 27, which is connected in series between the first power supply terminal L of the power supply and the input terminal of the power factor correction circuit 31.

[0098] Therefore, in discharge mode, the connection between the power supply and the power factor correction circuit 31 can be cut off by the third switch circuit 27; in charging mode, the connection between the power supply and the power factor correction circuit 31 can be turned on by the third switch circuit 27.

[0099] Optionally, the switching function of the third switching circuit 27 can be implemented by the second relay unit.

[0100] As shown in Figure 3, in another embodiment of this application, the online uninterruptible power supply further includes a third selection circuit 32. The third selection circuit 32 is connected to the input terminal of the power factor correction circuit 31, the output terminal of the half-bridge inverter circuit 24, and the load. It is used to control the connection of the input terminal of the power factor correction circuit 31 to the load, or to control the connection of the output terminal of the half-bridge inverter circuit 24 to the load. Optionally, the third selection circuit 32 includes a third relay unit, which implements the above-mentioned control function. Since the function of the third selection circuit 32 is the same as that of the first selection circuit 11 and the second selection circuit 20, the working principle of the third selection circuit 32 will not be described in detail here.

[0101] When in charging mode, the third switch circuit 27 is closed. At this time, if the third selection circuit 32 controls the input of the power factor correction circuit 31 to connect to the load, it means that the power supply provides the required operating voltage to the load. If the third selection circuit 32 controls the output of the half-bridge inverter circuit 24 to connect to the load, it means that the AC power output from the power supply passes through the power factor correction circuit 31 and the half-bridge inverter circuit 24 before providing the required operating voltage to the load. Optionally, the latter method can improve the power factor of the power supply.

[0102] In another embodiment of this application, the online uninterruptible power supply further includes a control circuit (not shown in the figure). The control circuit is connected to the push-pull circuit 16, the first selection circuit 11, the second selection circuit 20, the third selection circuit 32, the upper first switching circuit 19, the lower first switching circuit 19, the second switching circuit 30, the third switching circuit 27, and the half-bridge inverter circuit 24. The control circuit controls the operating state of these circuits to control the charging and discharging process (e.g., charging and discharging current) of the DC power supply 10. For example, it controls the on / off state of each power switch and each coil in these circuits to control the charging and discharging process of the DC power supply 10.

[0103] In summary, the online uninterruptible power supply provided in this application embodiment, by adding a first selection circuit 11, a first inductor filter circuit 12, and two first unidirectional conduction circuits 13 to the primary winding P side, and adding two first switching circuits 19, a second selection circuit 20, and a DC blocking circuit 21 to the secondary winding S side, enables the online uninterruptible power supply to transmit electrical energy bidirectionally, improves the utilization rate of components in the circuit, reduces costs, and can charge the DC power supply 10 with a lower secondary winding S voltage, and prevents low-frequency current from flowing into the secondary winding S in charging mode.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An online uninterruptible power supply, characterized in that, include: A push-pull circuit is configured to connect its two ends to the two ends of the primary winding of the transformer, and its common terminal to the negative terminal of the DC power supply; a first selection circuit, in the discharge mode of the DC power supply, is configured to control the positive terminal of the DC power supply to connect to the tap of the primary winding, and in the charging mode of the DC power supply, control the positive terminal of the DC power supply to connect to one end of a first inductor filter circuit, the other end of the first inductor filter circuit being connected to the cathodes of two first unidirectional conduction circuits, and the anodes of the two first unidirectional conduction circuits being connected to the two ends of the primary winding respectively; a first full-bridge rectifier circuit includes a first bridge arm and a second bridge arm connected in parallel, the midpoint of the first bridge arm being connected to the same-name terminal of the secondary winding of the transformer, the tap of the secondary winding being also connected to the common output terminal of a power factor correction circuit, and the input terminal of the power factor correction circuit being connected to the power supply; A second selection circuit is used to control the connection of the opposite-named terminal of the secondary winding to the midpoint of the second bridge arm in the discharge mode, and to connect one end of the DC blocking circuit in the charging mode; two first switching circuits are configured such that one is connected in series between the first bus output terminal of the power factor correction circuit and the other end of the DC blocking circuit, and the other is connected in series between the other end of the DC blocking circuit and the second bus output terminal of the power factor correction circuit; two second inductor filter circuits are configured such that one is connected in series between the cathode of the second bridge arm and the first bus output terminal, and the other is connected in series between the anode of the second bridge arm and the second bus output terminal; a half-bridge inverter circuit is configured such that its input terminal is connected to the power factor correction circuit and its output terminal is connected to the load.

2. The online uninterruptible power supply according to claim 1, characterized in that, The DC blocking circuit includes a first capacitor, the two ends of which are respectively connected to the second selection circuit and the other end of the first switching circuit, for preventing low-frequency current from passing through the secondary winding in the charging mode.

3. The online uninterruptible power supply according to claim 1, characterized in that, The first unidirectional conduction circuit includes a diode; one of the diodes in the first unidirectional conduction circuit is connected in series between the other end of the first inductor filter circuit and the same-named end of the primary winding; and / or, another diode in the first unidirectional conduction circuit is connected in series between the other end of the first inductor filter circuit and the opposite-named end of the primary winding.

4. The online uninterruptible power supply according to claim 1, characterized in that, The first inductor filter circuit includes: a first inductor, one end of which is connected to the first selection circuit, and the other end of which is connected to the cathodes of the two first unidirectional conduction circuits, for filtering the charging current of the DC power supply in the discharge mode.

5. The online uninterruptible power supply according to claim 1, characterized in that, The online uninterruptible power supply further includes: a first filter circuit, connected in series between the positive and negative terminals of the DC power supply.

6. The online uninterruptible power supply according to any one of claims 1 to 5, characterized in that, The power factor correction circuit includes: a third inductor filter circuit connected in series between the first power supply terminal of the power supply and the anode of the second unidirectional conduction circuit, wherein the anode of the second unidirectional conduction circuit is also connected to the cathode of the third unidirectional conduction circuit; a second full-bridge rectifier circuit including a third bridge arm and a fourth bridge arm connected in parallel, wherein the midpoint of the third bridge arm is connected to the anode of the second unidirectional conduction circuit, and the midpoint of the fourth bridge arm is connected to the second power supply terminal of the power supply and the tap of the secondary winding; a second switching circuit connected in series between the cathode and the anode of the second bridge arm; a second filter circuit configured such that one end is the first bus output terminal and connected to the cathode of the second unidirectional conduction circuit, and the other end is the common output terminal and connected to one end of the third filter circuit and the tap of the secondary winding; the third filter circuit configured such that the other end is the second bus output terminal and connected to the anode of the third unidirectional conduction circuit.

7. The online uninterruptible power supply according to any one of claims 1 to 5, characterized in that, The half-bridge inverter circuit includes: a first power switch bridge arm connected in parallel between the first bus output terminal and the second bus output terminal; and a fourth filter circuit configured to connect one end to the midpoint of the first power switch bridge arm and the other end to the common output terminal, and the fourth filter circuit is also used to connect the load.

8. The online uninterruptible power supply according to claim 7, characterized in that, The fourth filter circuit includes: a second inductor, configured to connect one end to the midpoint of the first power switch bridge arm and the other end to one end of a second capacitor; the second capacitor, configured to connect the other end to the common output terminal, and the two ends of the second capacitor are also used to connect the load.

9. The online uninterruptible power supply according to any one of claims 1 to 5, characterized in that, The online uninterruptible power supply further includes: a third selection circuit, connected to the input terminal of the power factor correction circuit, the output terminal of the half-bridge inverter circuit, and the load, for controlling the input terminal of the power factor correction circuit to be connected to the load, or controlling the output terminal of the half-bridge inverter circuit to be connected to the load.

10. The online uninterruptible power supply according to any one of claims 1 to 5, characterized in that, The online uninterruptible power supply further includes a fourth switching circuit, connected in series between the power supply and the input terminal of the power factor correction circuit.

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