High-reliability UPS power circuit

Abstract

The utility model relates to the technical field of uninterruptible power supplies, and discloses a high-reliability UPS power circuit, which comprises an alternating current input end, a rectification and FPC circuit, an inverter circuit, a battery, a bypass circuit and a short-circuit protection device, wherein the alternating current input end, the rectification and FPC circuit and the inverter circuit are connected in sequence; the input end of the bypass circuit is connected with the AC input end, and the output end of the bypass circuit is connected with the load; the battery is connected with the rectifier and FPC circuit; the output end of the inverter circuit is connected with the short-circuit protection device; the short-circuit protection device is connected with a load. According to the utility model, on the basis of a conventional UPS power circuit, the output end of the inverter circuit is connected in series with the short-circuit protection device, so that when the inverter circuit is short-circuited and a relay of the inverter circuit cannot be disconnected, the fuse is disconnected under the impact of short-circuit current, thereby preventing a bypass circuit from being short-circuited and ensuring that a load is not powered off; and the reliability of the UPS is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of uninterruptible power supply, in particular to a UPS power circuit with high reliability. Background Art

[0002] UPS (Uninterruptible Power Supply) is an uninterruptible power supply with an energy storage device. It is mainly used to provide uninterruptible power supply to some equipment with high requirements on power supply stability. It is currently widely used in power plants, data centers and other places with high requirements on power reliability.

[0003] When a UPS fails, ensuring that the UPS output does not lose power is an important manifestation of high reliability. Under normal circumstances, the UPS supplies power to the load after rectification by the rectifier circuit and inversion by the inverter circuit; if the UPS inverter circuit fails, it will switch to the bypass to supply power to the load. At this time, if the inverter circuit is short-circuited, the relay of the inverter circuit may not be disconnected in time during the process of switching to the bypass power supply, causing the bypass inverter to be directly connected, and the bypass is also short-circuited, eventually causing the load to lose power.

[0004] Therefore, it is necessary to improve the existing technology.

[0005] The above information is presented as background information only to assist with understanding the present disclosure and no determination or admission is made as to whether any of the above may be used as prior art with respect to the present disclosure. Utility Model Content

[0006] The utility model provides a UPS power circuit with high reliability to solve the problems existing in the prior art.

[0007] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0008] A high-reliability UPS power circuit includes an AC input terminal, a rectifier and FPC circuit, an inverter circuit, a battery, a bypass circuit, and a short-circuit protection device; wherein:

[0009] The AC input terminal, the rectifier and FPC circuit, and the inverter circuit are connected in sequence;

[0010] The input end of the bypass circuit is connected to the AC input end, and the output end of the bypass circuit is connected to the load;

[0011] The battery is connected to the rectification and FPC circuit;

[0012] The output end of the inverter circuit is connected to the short-circuit protection device;

[0013] The short-circuit protection device is connected to the load.

[0014] Furthermore, in the high-reliability UPS power circuit, the short-circuit protection device is a fuse F1.

[0015] Furthermore, in the high-reliability UPS power circuit, the fuse F1 is a fast fuse.

[0016] Furthermore, in the high-reliability UPS power circuit, the overcurrent capacity of the fuse F1 is greater than the maximum output current of the inverter circuit.

[0017] Further, in the high-reliability UPS power circuit, the bypass circuit includes a first thyristor SCR1 and a second thyristor SCR2;

[0018] The first thyristor SCR1 and the second thyristor SCR are connected in reverse parallel.

[0019] Further, in the high-reliability UPS power circuit, the inverter circuit includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a first power switch tube Q1, a second power switch tube Q2, a third power switch tube Q3, a fourth power switch tube Q4, an inductor L1 and a relay RLY1;

[0020] The emitter of the second power switch tube Q2 is connected to the emitter of the third power switch tube Q3, the collector of the second power switch tube Q2 is connected to the rectification and FPC circuit, and the collector of the third power switch tube Q3 is connected to the inductor L1;

[0021] The inductor L1 is connected to the relay RLY1;

[0022] The relay RLY1 is connected to the short-circuit protection device;

[0023] The collector of the first power switch tube Q1 is connected to the rectification and FPC circuit, and the emitter of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1;

[0024] The emitter of the fourth power switch tube Q4 is connected to the rectification and FPC circuit, and the collector of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1;

[0025] One end of the first capacitor C1 is connected between the collector of the first power switch tube Q1 and the rectification and FPC circuit, and the other end of the first capacitor C1 is connected between the collector of the second power switch tube Q2 and the rectification and FPC circuit;

[0026] One end of the second capacitor C2 is connected between the emitter of the fourth power switch tube Q4 and the rectifier and FPC circuit, and the other end of the second capacitor C2 is connected between the collector of the second power switch tube Q2 and the rectifier and FPC circuit;

[0027] A connection node between the first capacitor C1 and the second capacitor C2 is connected to the negative input terminal of the AC input terminal;

[0028] One end of the third capacitor C3 is connected between the inductor L1 and the relay RLY1 , ​​and the other end of the third capacitor C3 is connected to the negative input end of the AC input end.

[0029] Furthermore, in the high-reliability UPS power circuit, the normally-open end of the relay RLY1 is connected to the short-circuit protection device.

[0030] Furthermore, in the high-reliability UPS power circuit, the first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, and the fourth power switch tube Q4 are all IGBT tubes.

[0031] Furthermore, in the high-reliability UPS power circuit, the overcurrent capability of the fuse F1 is smaller than the overcurrent capability of the first thyristor SCR1 and the second thyristor SCR2.

[0032] Furthermore, in the high-reliability UPS power circuit, the overcurrent capacity of the fuse F1 is greater than the maximum current flowing through the relay RLY1 when the bypass circuit and the inverter circuit are switched normally.

[0033] Compared with the prior art, the utility model has the following beneficial effects:

[0034] The utility model provides a high-reliability UPS power circuit. On the basis of a conventional UPS power circuit, a short-circuit protection device is connected in series at the output end of an inverter circuit, so that when a short circuit occurs in the inverter circuit and the relay of the inverter circuit cannot be disconnected, the fuse is disconnected under the impact of the short-circuit current, thereby preventing the bypass circuit from being short-circuited, ensuring that the load is not powered off, and improving the reliability of the UPS.

[0035] The present invention has other characteristics and advantages, which will be apparent from the accompanying drawings and subsequent specific embodiments incorporated herein, or will be described in detail in the accompanying drawings and subsequent specific embodiments incorporated herein, which together are used to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a circuit principle diagram of a conventional UPS power circuit in the prior art;

[0038] Figure 2 This is a circuit principle diagram of a high-reliability UPS power circuit provided by an embodiment of the utility model;

[0039] Figure 3 This is a circuit principle diagram of a high-reliability UPS power circuit provided by an embodiment of the utility model;

[0040] Figure 4 It is a schematic diagram of a time current curve of a fuse provided by an embodiment of the utility model;

[0041] Figure 5 It is a schematic diagram of the short-circuit waveform of the inverter circuit after the series fuse provided by the embodiment of the utility model.

[0042] Reference numerals:

[0043] AC input terminal 1, rectification and FPC circuit 2, inverter circuit 3, battery 4, bypass circuit 5, short-circuit protection device 6, load 7. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. In addition, ordinary technicians in this field can know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0045] In the description of the present application, it should be understood that, unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those commonly understood by those skilled in the art of the present application. In addition, any terminology used is only for the purpose of describing specific embodiments and is not intended to limit the present application.

[0046] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0047] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0048] Embodiment 1

[0049] In view of the defects of the above-mentioned prior art, the applicant, based on many years of rich practical experience and professional knowledge in the design and manufacture of such products, and in conjunction with the application of theory, actively conducts research and innovation in the hope of creating a technology that can solve the defects of the prior art. After continuous research and design, and after repeated trial samples and improvements, the present utility model with real practical value was finally created.

[0050] Please refer to Figure 2 The embodiment of the utility model provides a high-reliability UPS power circuit, including an AC input terminal 1, a rectifier and FPC circuit 2, an inverter circuit 3, a battery 4, a bypass circuit 5 and a short-circuit protection device 6; wherein,

[0051] The AC input terminal 1, the rectifier and FPC circuit 2, and the inverter circuit 3 are connected in sequence;

[0052] The input end of the bypass circuit 5 is connected to the AC input end 1, and the output end of the bypass circuit 5 is connected to the load 7;

[0053] The battery 4 is connected to the rectification and FPC circuit 2;

[0054] The output end of the inverter circuit 3 is connected to the short-circuit protection device 6;

[0055] The short-circuit protection device 6 is connected to the load 7 .

[0056] It should be noted that this embodiment is based on a conventional UPS power circuit, and a short-circuit protection device is connected in series at the output end of the inverter circuit, so that when a short circuit occurs in the inverter circuit and the relay of the inverter circuit cannot be disconnected, the fuse is disconnected under the impact of the short-circuit current, thereby preventing the bypass circuit from being short-circuited, ensuring that the load is not powered off, and improving the reliability of the UPS.

[0057] Please refer again Figure 2 , and combined with reference Figure 3 In this embodiment, the short-circuit protection device 6 is a fuse F1.

[0058] Please refer again Figure 2 and 3 In this embodiment, the bypass circuit 5 includes a first thyristor SCR1 and a second thyristor SCR2;

[0059] The first thyristor SCR1 and the second thyristor SCR are connected in reverse parallel.

[0060] Please refer again Figure 2 and 3 In this embodiment, the inverter circuit 3 includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a first power switch tube Q1, a second power switch tube Q2, a third power switch tube Q3, a fourth power switch tube Q4, an inductor L1 and a relay RLY1;

[0061] The emitter of the second power switch tube Q2 is connected to the emitter of the third power switch tube Q3, the collector of the second power switch tube Q2 is connected to the rectification and FPC circuit 2, and the collector of the third power switch tube Q3 is connected to the inductor L1;

[0062] The inductor L1 is connected to the relay RLY1;

[0063] The relay RLY1 is connected to the short-circuit protection device 6;

[0064] The collector of the first power switch tube Q1 is connected to the rectification and FPC circuit 2, and the emitter of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1;

[0065] The emitter of the fourth power switch tube Q4 is connected to the rectification and FPC circuit 2, and the collector of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1;

[0066] One end of the first capacitor C1 is connected between the collector of the first power switch tube Q1 and the rectification and FPC circuit 2, and the other end of the first capacitor C1 is connected between the collector of the second power switch tube Q2 and the rectification and FPC circuit 2;

[0067] One end of the second capacitor C2 is connected between the emitter of the fourth power switch tube Q4 and the rectifier and FPC circuit 2, and the other end of the second capacitor C2 is connected between the collector of the second power switch tube Q2 and the rectifier and FPC circuit 2;

[0068] A connection node between the first capacitor C1 and the second capacitor C2 is connected to the negative input terminal of the AC input terminal 1;

[0069] One end of the third capacitor C3 is connected between the inductor L1 and the relay RLY1 , ​​and the other end of the third capacitor C3 is connected to the negative input end of the AC input end 1 .

[0070] Optionally, the normally open end of the relay RLY1 is connected to the short-circuit protection device 6 .

[0071] Optionally, the first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, and the fourth power switch tube Q4 are all IGBT tubes.

[0072] It should be noted that conventional UPS power circuits such as Figure 1 As shown, the only difference from the high reliability UPS power circuit provided in this embodiment is that there is no short-circuit protection device 6, that is, fuse F1. Figure 1 In the embodiment, the inverter circuit is composed of the first capacitor C1, the second capacitor C2, the third capacitor C3, the first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, the fourth power switch tube Q4, the inductor L1 and the relay RLY1, and the bypass circuit is composed of the first thyristor SCR1 and the second thyristor SCR2. Point A is the L line input end of the load, point B is the N line input end of the load, and point C is the normally open end of the relay RLY1 (the same is true for the reliable UPS power circuit provided in this embodiment). Under normal circumstances, the AC input is supplied to the load after the rectification and PFC circuit and the inverter circuit, and the first thyristor SCR1 and the second thyristor SCR2 in the bypass circuit are turned off; when the inverter circuit is short-circuited, such as the third capacitor C3 is short-circuited, at this time, according to the normal UPS switching logic, the first thyristor SCR1 and the second thyristor SCR2 in the bypass circuit are turned on, and the relay RLY1 cannot be disconnected in time due to the large short-circuit current. Figure 1 Points A and B are short-circuited, and the load loses power. In addition, the AC input passes through the first thyristor SCR1, the second thyristor SCR2, the relay RLY1, and the short-circuited first capacitor C1 to form a short-circuit loop, and the first thyristor SCR1 and the second thyristor SCR2 are damaged.

[0073] The UPS power circuit optimized in this embodiment is as follows Figure 2 As shown, specifically in Figure 1 On the basis of the above, a fuse F1 is connected in series at the normally open end of the relay RLY1, i.e., point C; when a short circuit occurs in the inverter circuit, for example, the third capacitor C3 is short-circuited, the AC input passes through the first thyristor SCR1, the second thyristor SCR2, the relay RLY1, the fuse F1, and the short-circuited first capacitor C1 loop to form a large current. The instantaneous fuse F1 is disconnected, and the short circuit between points A and B is eliminated. The AC input passes through the first thyristor SCR1 and the second thyristor SCR2 to supply power to the load 7, and the load 7 does not lose power.

[0074] In this embodiment, the fuse F1 needs to be a fast fuse. The overcurrent capacity I^2t of the fuse F1 should be less than the overcurrent capacity I^2t of the first thyristor SCR1 and the second thyristor SCR2, to ensure that when the AC input passes through the first thyristor SCR1, the second thyristor SCR2, the relay RLY1, and the short-circuited first capacitor C1 to form a short-circuit loop, the fuse F1 is disconnected and the first thyristor SCR1 and the second thyristor SCR2 operate normally.

[0075] In this embodiment, the overcurrent capacity of the fuse F1 should be greater than the maximum output current of the inverter circuit 3 to ensure that the fuse F1 is not damaged when the inverter circuit 3 is normally loaded.

[0076] In this embodiment, the overcurrent capacity of the fuse F1 should be greater than the maximum current flowing through the relay RLY1 when the bypass circuit 5 and the inverter circuit 3 are switched normally, to ensure that the fuse F1 is not damaged when the inverter and bypass modes of the UPS are switched.

[0077] Through the above design, when the inverter circuit 3 inside the UPS is short-circuited, the fuse F1 is disconnected, the bypass circuit 5 is not short-circuited, the first thyristor SCR1 and the second thyristor SCR2 operate normally, the load 7 does not lose power, and the fuse F1 will not be damaged when the UPS operates normally.

[0078] Next, this embodiment is described by taking a 5KVA power UPS as an example.

[0079] (1) Figure 3 The middle fuse F1 is rated at 50A and has a breaking I^2t of 778A^2S.

[0080] (2) The rated current of the first thyristor SCR1 and the second thyristor SCR2 is 50A, and the maximum I^2t is 2113A^2S; the overcurrent capacity I^2t of the fuse F1 is less than the overcurrent capacity I^2t of the first thyristor SCR1 and the second thyristor SCR2; when the AC input forms a short-circuit loop through the first thyristor SCR1, the second thyristor SCR2, the relay RLY1, and the short-circuited first capacitor C1, the fuse F1 is disconnected and the first thyristor SCR1 and the second thyristor SCR2 operate normally;

[0081] (3) UPS rated output voltage 220V, UPS rated output current effective value 27.73A, according to 200% overload 200mS, inverter overload maximum current effective value 55.46A, continuous 200mS; according to Figure 4The time-current curve of the fuse F1 shown in the figure shows that the overcurrent capacity of the fuse F1 for 200mS is 200A, which is greater than the maximum output current of the inverter circuit 3, ensuring that the fuse F1 will not be damaged when the inverter circuit 3 is normally loaded;

[0082] (4) Test the maximum current flowing through relay RLY1 during normal bypass and inverter switching of UPS, which is 400A and lasts for 10uS; Figure 4 As shown in the time-current curve of fuse F1, the overcurrent capacity of fuse F1 below 100uS is greater than 1000A, ensuring that fuse F1 will not be damaged when the UPS is switched between inverter and bypass modes.

[0083] (5) According to the above selection and design of fuse F1, the third capacitor C3 in the inverter circuit 3 of the UPS is simulated to be short-circuited. The test waveform is as follows: Figure 5 , Figure 5 Where CH1 is the current of relay RLY1, CH2 is the voltage across the third capacitor C3, CH3 is the short-circuit current of the third capacitor C3, and CH4 is the voltage between points A and B of the load; after the short-circuit fault occurs, the fuse F1 is damaged, and the first thyristor SCR1 and the second thyristor SCR2 work normally, ensuring that the load 7 does not lose power, thereby improving the reliability of the UPS.

[0084] Although the terms such as AC input terminal, rectifier and FPC circuit, inverter circuit, battery, etc. are used more frequently in this application, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the utility model; interpreting them as any additional restrictions is contrary to the spirit of the utility model.

[0085] The utility model provides a high-reliability UPS power circuit. On the basis of a conventional UPS power circuit, a short-circuit protection device is connected in series at the output end of an inverter circuit, so that when a short circuit occurs in the inverter circuit and the relay of the inverter circuit cannot be disconnected, the fuse is disconnected under the impact of the short-circuit current, thereby preventing the bypass circuit from being short-circuited, ensuring that the load is not powered off, and improving the reliability of the UPS.

[0086] In summary, after reading this detailed disclosure, it will be apparent to those skilled in the art that the aforementioned detailed disclosure may be presented only by way of example and may not be restrictive. Although not explicitly stated herein, it will be appreciated by those skilled in the art that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are intended to be proposed by this application and are within the spirit and scope of the exemplary embodiments of this application.

[0087] In addition, certain terms in this application have been used to describe embodiments of the present application. For example, "one embodiment", "embodiment" and / or "some embodiments" mean that a particular feature, structure or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. Therefore, it can be emphasized and should be understood that two or more references to "embodiment" or "one embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics may be appropriately combined in one or more embodiments of the present application.

[0088] It should be understood that in the foregoing description of the embodiments of the present application, in order to help understand a feature and for the purpose of simplifying the present application, the present application combines various features in a single embodiment, drawing or its description. However, this does not mean that the combination of these features is necessary. When reading the present application, it is entirely possible for a person skilled in the art to extract some of the features and understand them as separate embodiments. In other words, the embodiments in the present application can also be understood as the integration of multiple secondary embodiments. This is also true when the content of each secondary embodiment is less than all the features of a single aforementioned disclosed embodiment.

[0089] Finally, it should be understood that the embodiments of the application disclosed herein are explanations of the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely examples and not limitations. Those skilled in the art can adopt alternative configurations according to the embodiments in the present application to implement the application in the present application. Therefore, the embodiments of the present application are not limited to the embodiments accurately described in the application.

Claims

1. A high reliability UPS power circuit, characterized in that: It comprises an AC input terminal (1), a rectifier and FPC circuit (2), an inverter circuit (3), a battery (4), a bypass circuit (5) and a short-circuit protection device (6); wherein: The AC input terminal (1), the rectifier and FPC circuit (2), and the inverter circuit (3) are connected in sequence; The input end of the bypass circuit (5) is connected to the AC input end (1), and the output end of the bypass circuit (5) is connected to a load (7); The battery (4) is connected to the rectification and FPC circuit (2); The output end of the inverter circuit (3) is connected to the short-circuit protection device (6); The short-circuit protection device (6) is connected to the load (7).

2. The high reliability UPS power circuit according to claim 1, characterized in that: The short-circuit protection device (6) is a fuse F1.

3. The high reliability UPS power circuit according to claim 2, characterized in that: The fuse F1 is a fast fuse.

4. The high reliability UPS power circuit according to claim 2, characterized in that: The overcurrent capacity of the fuse F1 is greater than the maximum output current of the inverter circuit (3).

5. The high reliability UPS power circuit according to claim 2, characterized in that: The bypass circuit (5) comprises a first thyristor SCR1 and a second thyristor SCR2; The first thyristor SCR1 and the second thyristor SCR are connected in reverse parallel.

6. The high reliability UPS power circuit according to claim 5, characterized in that: The inverter circuit (3) comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a first power switch tube Q1, a second power switch tube Q2, a third power switch tube Q3, a fourth power switch tube Q4, an inductor L1 and a relay RLY1; The emitter of the second power switch tube Q2 is connected to the emitter of the third power switch tube Q3, the collector of the second power switch tube Q2 is connected to the rectification and FPC circuit (2), and the collector of the third power switch tube Q3 is connected to the inductor L1; The inductor L1 is connected to the relay RLY1; The relay RLY1 is connected to the short-circuit protection device (6); The collector of the first power switch tube Q1 is connected to the rectification and FPC circuit (2), and the emitter of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1; The emitter of the fourth power switch tube Q4 is connected to the rectification and FPC circuit (2), and the collector of the first power switch tube Q1 is connected between the collector of the third power switch tube Q3 and the inductor L1; One end of the first capacitor C1 is connected between the collector of the first power switch tube Q1 and the rectification and FPC circuit (2), and the other end of the first capacitor C1 is connected between the collector of the second power switch tube Q2 and the rectification and FPC circuit (2); One end of the second capacitor C2 is connected between the emitter of the fourth power switch tube Q4 and the rectification and FPC circuit (2), and the other end of the second capacitor C2 is connected between the collector of the second power switch tube Q2 and the rectification and FPC circuit (2); A connection node between the first capacitor C1 and the second capacitor C2 is connected to the negative input terminal of the AC input terminal (1); One end of the third capacitor C3 is connected between the inductor L1 and the relay RLY1, and the other end of the third capacitor C3 is connected to the negative input end of the AC input end (1).

7. The high reliability UPS power circuit according to claim 6, characterized in that: The normally open end of the relay RLY1 is connected to the short-circuit protection device (6).

8. The high reliability UPS power circuit according to claim 6, characterized in that: The first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, and the fourth power switch tube Q4 are all IGBT tubes.

9. The high reliability UPS power circuit according to claim 6, characterized in that: The over-current capability of the fuse F1 is smaller than the over-current capability of the first thyristor SCR1 and the second thyristor SCR2.

10. The high reliability UPS power circuit according to claim 6, characterized in that: The overcurrent capacity of the fuse F1 is greater than the maximum current flowing through the relay RLY1 when the bypass circuit (5) and the inverter circuit (3) are switched normally.

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