A phase tracking emergency power supply and power supply method thereof

Abstract

The present application provides a phase-tracking emergency power supply and a power supply method thereof, wherein the power supply comprises: a voltage input module, on which an input switch is provided; an AC / DC module, connected to the voltage input module; a power storage module: connected to the AC / DC module; a DC / AC module, connected to the power storage module, and an output switch is connected to the output end of the DC / AC module; a control unit is embedded in the DC / AC module; a comparison module is connected to the control unit and the voltage input module; in the phase-tracking emergency power supply of the present application, when the AC power supply is normally supplied, the DC / AC module output tracks the AC power phase in real time, and when the AC power is abnormal, the DC / AC module output power is switched to the DC / AC module output power in a dual power supply manner, thereby realizing basically seamless switching of the load power supply.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a phase tracking emergency power supply and a power supply method thereof. Background Art

[0002] In important places such as examinations, important meetings, large gatherings, etc., power supply must not be interrupted during the activities. Since the power supply demand is temporary and the power supply is required to be low-noise, commonly used power supply equipment such as diesel generators are not suitable.

[0003] The commonly used power supplies in the prior art mainly include emergency power supplies (EPS) and dynamic voltage recovery devices (DVRs). However, the emergency power supply (EPS) has some limitations in meeting the power protection performance of sensitive loads such as electronic screens, computers, and storage devices. Specifically, the current EPS uses ATS as the main switching component, which results in an overall switching speed of more than 100 milliseconds. Therefore, short-term voltage fluctuations, interruptions, and even power outages may occur during the switching process. Sensitive loads such as electronic screens, computers, and storage devices have extremely high requirements for voltage stability. Instantaneous voltage fluctuations and interruptions may cause these devices to experience data loss, freezes, restarts, and other problems, affecting their normal operation. In addition, the dynamic voltage recovery device (DVR) is a power electronic device with supercapacitors as its main body. Its purpose is to solve the instantaneous interruption of voltage. The output is generally short-term (generally seconds) high power, which is not suitable for the power protection of the above-mentioned important places at the hour level.

[0004] In summary, conventional emergency power supplies (EPS) and dynamic voltage recovery devices (DVR) have certain limitations for emergency power supply in important places such as examinations, important meetings, large gatherings, etc. This application intends to provide a quiet and fast emergency power supply. After a detailed search, the applicant has not found any relevant prior art. Therefore, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0005] The present application provides a phase tracking emergency power supply, comprising:

[0006] A voltage input module is used for inputting voltage; an input switch is provided on the voltage input module;

[0007] AC / DC module, connected to the voltage input module, used to convert AC power into DC power;

[0008] Power storage module: connected to the AC / DC module, the AC / DC module charges the power storage module;

[0009] A DC / AC module, connected to the power storage module, for converting direct current into alternating current;

[0010] An output switch is connected to the output end of the DC / AC module; a control unit is embedded in the DC / AC module;

[0011] The comparison module is connected with the control unit and the voltage input module and is used for comparing the phase of the voltage of the voltage input module. The control unit controls the output phase of the comparison module to be the same as that of the voltage input module.

[0012] As a preferred solution, the AC / DC module adopts a rectifier bridge, and a DC support capacitor is arranged between the output ends of the rectifier bridge.

[0013] As a preferred solution, the AC / DC module adopts a battery charger, and at least one phase of the voltage input module is connected to the AC / DC module.

[0014] As a preferred solution, the input switch includes an original power input switch DL1, and a thyristor is arranged in parallel on the original power input switch DL1.

[0015] As a preferred solution, the thyristor is a single-phase thyristor or a bidirectional thyristor.

[0016] As a preferred solution, the output switch includes an input switch DL2 of a backup power supply, a thyristor is arranged in parallel with the input switch DL2 of the backup power supply, or the output switch includes a thyristor.

[0017] As a preferred solution, the original power input switch DL1 and the backup power input switch DL2 are both fast-opening switches.

[0018] A power supply method for a phase tracking emergency power supply comprises the following steps:

[0019] S1: When the mains power is normal, the input switch is closed and the output switch is open. The voltage input module supplies power to the load and the power storage module is charged through the AC / DC module.

[0020] S2: The control unit monitors the phase of the voltage input module and controls the output phase of the DC / AC module to be the same as the output phase of the voltage input module; or when the mains voltage is equal to 99% of the voltage upper limit, the output phase of the DC / AC module is adjusted to lag behind the output phase of the voltage input module;

[0021] S3: When the mains power is abnormal, the input switch is opened and the output switch is closed, and the load is powered by the power storage module.

[0022] As a preferred solution, S2 specifically includes:

[0023] S21: Determine whether the voltage V1 of the voltage input module is greater than the upper limit V of the phase voltage of the voltage input module max, jump to S22, otherwise jump to S23;

[0024] S22: The control unit adjusts the phase of the DC / AC module output voltage V2 to ensure that the phase difference Δψ between V2 and V1 is ≥ ψ; wherein ψ is a positive phase angle close to 0, and the value is 5°;

[0025] S23: Determine whether the voltage V1 of the voltage input module is less than the lower limit V of the phase voltage of the voltage input module min , jump to S22, otherwise jump to S24;

[0026] S24: Determine whether the output voltage V2 of the DC / AC module is greater than or equal to V1+ΔV, where ΔV is the margin of the voltage difference; if yes, adjust to S25, otherwise jump to S26;

[0027] S25: The control unit adjusts the phase of the DC / AC module output voltage V2 to ensure that ψ>Δψ≥0;

[0028] S26: adjust and increase V2;

[0029] S27: Determine whether JSQ is greater than N, where N means that the inverter needs N cycles to adjust the voltage to the expected value, and JSQ is a cycle counter for determining the DC / AC module voltage V2; if yes, jump to S28, otherwise jump to S21;

[0030] S28: Start the backup adjustment to make V2 phase lag and ensure Δψ≥ψ.

[0031] As a preferred solution, before the control unit S22 adjusts the phase of the DC / AC module output voltage V2, it first outputs an alarm.

[0032] The phase tracking emergency power supply of the present application tracks the AC power phase in real time when the AC power supply is normal. When the AC power supply is abnormal, the DC / AC module output switches to the DC / AC module output power in a dual power supply mode to achieve basically seamless switching of the load power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the first embodiment of the present application;

[0034] Figure 2 It is a structural diagram of Embodiment 2 of the present application;

[0035] Figure 3 It is a structural diagram of the third embodiment of the present application;

[0036] Figure 4 It is a schematic diagram between the control system and various structures of the present application;

[0037] Figure 5 This is a structural diagram of Embodiment 4 of the present application;

[0038] Reference numerals:

[0039] 1. Voltage input module; 2. Single-phase thyristor; 3. AC / DC module; 4. DC support capacitor; 5. Power storage module; 6. DC / AC module; 7. Control unit; 8. Comparison module; 9. Master control module; 10. Bidirectional thyristor. DETAILED DESCRIPTION

[0040] The following is combined with Figure 1 To Attachment Figure 5 The specific implementation of the present invention is described in detail. It should be noted that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0041] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "connected", "connected" and "provided with" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements; for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Embodiment 1

[0043] The present application provides a phase tracking emergency power supply, comprising:

[0044] The voltage input module 1 is used to input the mains voltage, that is, input the mains to the load; the voltage input module 1 in this embodiment adopts a three-phase four-wire system, as shown in FIG1, Figure 2 , Figure 3A1, B1, C1 in the diagram represent three phase lines (live wires), and N represents the neutral line; its main function is to effectively transmit the electric energy generated by the three-phase AC generator to various load devices; an input switch is provided on the voltage input module 1. In this embodiment, DL1A, DL1B, and DL1C are three-phase switch bodies, and each phase switch is connected in parallel with a group of single-phase thyristors 2, and all single-phase thyristors 2 are uniformly identified as SCR1; DL1A, DL1B, and DL1C together constitute the original power input switch DL1, which is a fast opening switch with an inherent opening time of the ms level. The fast opening switch can adopt a mechanical switch with a fast driving mechanism such as magnetic control, electromagnetic, and permanent magnet in the prior art; the fast opening switch can meet the fast commutation between the contacts of the switch bodies of DL1A, DL1B, and DL1C and the single-phase thyristors 2;

[0045] AC / DC module 3 is connected to voltage input module 1 and is used to convert alternating current into direct current. AC / DC module 3 can use a rectifier bridge or a battery charger. When a charger is selected, the front input voltage can only select one of the three phases, such as A and N. When a rectifier bridge is used, a DC support capacitor 4 is provided between the output ends of the rectifier bridge, and the DC support capacitor 4 is preferably an electrolytic capacitor.

[0046] Power storage module 5: connected to AC / DC module 3, AC / DC module 3 charges power storage module 5; power storage module 5 uses energy storage battery pack (power battery pack), which should meet the following four requirements at the same time: (1) high power density, high fire protection, and lithium-free; (2) long life, including a cycle life of more than 2,000 times and a calendar life of more than 5 years; (3) a wide temperature range to meet the outdoor temperature of -40°C to 70°C; (4) high energy density, which is conducive to reducing the overall weight and size, and is convenient for mobile management and use; this application selects zinc-nickel battery packs after actual measurement;

[0047] The DC / AC module 6 is connected to the power storage module 5 and is used to convert direct current into alternating current. The output end of the DC / AC module 6 is connected to an output switch, DL2A, DL2B, and DL2C are three-phase switch bodies, each phase switch is connected in parallel with a group of single-phase thyristors 2, and all single-phase thyristors 2 are uniformly marked as SCR2. DL2A, DL2B, and DL2C together constitute the input switch DL2 of the backup power supply, DL2 is also a fast-disconnecting switch, the same as DL1, and no specific details are given here. The control unit 7 is embedded in the DC / AC module 6. The DC / AC module 6 in this embodiment adopts an inverter, and the intermediate link CTR of the inverter is an embedded control unit 7, which is controlled by a single-chip microcomputer or DSP. The backup voltage generated by the inverter is no-load during hot standby, so that the backup power supply can be adjusted without affecting the load power supply. The output voltage of the inverter is controlled to be slightly higher than the mains voltage, but it must meet the national standard for the standard upper limit of 400V voltage, which can be achieved by dynamically adjusting the voltage of the energy storage battery pack.

[0048] The comparison module 8 is connected to the control unit 7 and the voltage input module 1, and is used to compare the phase of the voltage of the voltage input module 1. The control unit 7 controls the output phase of the inverter to be the same as the phase of the voltage input module 1. The comparison module 8 of this embodiment adopts a comparator, which compares the phase of the mains voltage and feeds back to the control unit 7 of the inverter to form a phase closed loop, thereby forming a function in which the inverter output no-load phase tracks the mains phase in real time. Figure 1 In the figure, phase A is taken as an example.

[0049] Preferably, if Figure 4 As shown, this embodiment also includes a master control module 9, which is connected to the voltage input module 1, the input switch, the output switch, the DC / AC module 6, the AC / DC module 3, the power storage module 5, and the comparison module 8. The master control module 9 uses a CPU, and the CPU controls the input switch and the output switch, and more specifically controls the three-phase switch body and the single-phase thyristor 2; the CPU controls the charging of the power storage module 5; the CPU includes the collection of information such as voltage and current, such as Figure 4 , realizing a closed loop among the CPU, inverter and hot standby voltage.

[0050] For the convenience of demonstration, the voltage input module 1 in this embodiment is described using three-phase four-wire common N, but the above scheme is also applicable to three-phase three-wire or three-phase four-wire not common N, or other wiring methods.

[0051] The working principle of this embodiment is as follows: when the mains is normal (according to the provisions of the power system, the allowable voltage deviation range of 400V is ±5% of the rated voltage, that is, the allowable line voltage range is 380V-420V, and the range of 380V-420V belongs to the normal range of the mains), the mains supplies power to the on-site loads, the DL1A, DL1B, DL1C switch bodies are closed, and the energy storage battery pack is charged through the voltage input module 1 to keep the battery pack fully charged; since the switches DL2A, DL2B, DL2C are in the open state, the output of the inverter is actually in a no-load state; at the same time, the control unit 7 in the inverter monitors the phase of the mains and controls the output phase of the inverter to be basically the same as the mains; when the mains is abnormal (including but not limited to low voltage, voltage fluctuation, power supply interruption, etc.), the master control module 9 of the entire system of the product determines the problem within 1-2ms, and the master control module 9 triggers the conduction of the single-phase thyristor SCR1 of each phase connected in parallel in DL1A, DL1B, DL1C, and the thyristor SCR1 of each phase connected in parallel in DL1 When the contacts of the A, DL1B, and DL1C switches are opened, the current is commutated to the single-phase thyristor branch SCR1 of each phase, and no arc is generated between the contacts (for the principle of forced replacement of thyristors, refer to the paper "Development of a New Dual Power Static Transfer Switch" (Zhang Kexi, Communication Power Technology, 2013, 30 (1): 67-70)). The single-phase thyristor SCR2 in DL2 is triggered to conduct according to the direction of the current in each phase of DL1; the backup power supply of this application is self-generated (the backup power supply can generate electricity by itself) , rather than obtaining it from the external power grid), so it is also controllable, and it is completely unloaded during hot standby, so it is also easy to control. The comparator is first used for phase monitoring and closed loop, and secondly for controlling the voltage of the backup power supply to always be equal to or slightly higher than the mains voltage; according to the logic of forced replacement of the main power supply and the backup power supply thyristor, when the conditions that the backup voltage is in phase and the voltage value is slightly higher are met, the conduction of the thyristor does not need to wait, and it is turned on as soon as it is triggered, thereby completing the seamless switching of the load from the mains power supply to the inverter power supply. Embodiment 2

[0052] This embodiment can greatly reduce the product size, specifically:

[0053] like Figure 2As shown, because DL1 and DL2 in Example 1 are both fast-disconnecting switches, they can achieve energy saving and ensure the ability to withstand load short circuits. When the switching is completed, the switch is used to connect the load to the power supply; but considering that after the EPS switches to the backup power supply, it generally only provides hours of endurance power supply. During this period, the loss caused by the conduction of the thyristor is almost negligible compared with the total endurance energy; for example, assuming a 30KW EPS with a battery life of 1 hour, the single-phase current is about 45A, and the voltage drop when the thyristor SCR2 is turned on is 2V. The power loss of each phase is 45*2=90W, accounting for 0.9% of the power of each phase, and the impact on the total endurance time can be ignored. At this time, the switch body DL2 in Example 1 can be cancelled, and only the single-phase thyristor group SCR2 is retained. At this time, the dual power switch is simplified to a single fast switch, which greatly reduces the product size. Embodiment 3

[0054] The difference between this embodiment and the first and second embodiments is that this embodiment does not consider the switchback scenario:

[0055] Specifically: during the battery life of the product during the power-saving switching, if the mains power is restored and it is necessary to switch back to the mains power supply in time, the unidirectional thyristor group SCR1 in the first and second embodiments is used; if the mains power is restored and it is not necessary to switch back to the mains power supply in time, the single-phase thyristor 2 of the input switch in the first and second embodiments can be used Figure 3 The bidirectional thyristor 10 shown is substituted. Embodiment 4

[0056] This embodiment provides a power supply method of a phase tracking emergency power supply.

[0057] According to the regulations of the power system, the allowable voltage deviation range of 400V is ±5% of the rated voltage, that is, the allowable line voltage range is 380V-420V, and the upper and lower limits of the phase voltage are marked as V max and V min , V max and V min It is not only related to the national standard, but sometimes also related to the specific type of load, and can be flexibly set on site; in this embodiment, the mains voltage is V1, the standby voltage output by the inverter is V2, and the control expected voltage V max>V2>V1+ΔV, where ΔV is the surplus of the voltage difference, ΔV in this embodiment is 1V-5V, and the expected phase difference Δψ is controlled to satisfy ψ>Δψ≥0 (since there is no absolute 0 value in the analog quantity acquisition of the single-chip microcomputer system, ψ is a positive phase angle close to 0, which can be set, preferably 5°), that is, the standby voltage lags behind or is equal to the mains voltage; assuming that the inverter needs N cycles to adjust the voltage to the expected value (if N cycles still cannot be adjusted to the expected value, it means that the battery voltage has reached the limit), where JSQ is a cycle counter for judging the inverter voltage; the overall control idea is: 1) Ensure that the inverter outputs the standby voltage in the same phase as the mains and has a slightly larger amplitude. Specifically, the output voltage amplitude of the inverter is 1% larger than the output voltage amplitude of the mains voltage - About 5%; its main purpose is to achieve seamless switching of load power supply; incidentally, the above can reduce the impact of switching. Specifically, when the inverter outputs the backup voltage in the same phase as the mains, the voltage impact on the load can be minimized during the switching between the mains and the backup power supply, because the same phase means that at the moment of switching, the voltage change trends of the backup power supply and the mains are consistent; and the slightly larger amplitude can ensure that there is enough voltage to maintain the normal operation of the load after switching, and can also compensate for the slight voltage drop that may occur during the switching process. This switching method can effectively avoid equipment failure or data loss due to voltage fluctuations; 2) Under extreme conditions, if the AC voltage is high enough and close to the voltage upper limit, specifically equal to 99% of the voltage upper limit, the main strategy in 1) becomes invalid and the backup strategy is enabled. The backup strategy is: adjust the backup voltage phase to slightly lag behind the AC voltage phase, and the switching time will increase. When the AC voltage is close to the voltage upper limit, if the switching is still carried out in the same phase and with a slightly larger amplitude, the load terminal voltage may exceed the rated voltage of the equipment, thereby causing damage to the equipment. Adjusting the backup voltage phase to slightly lag behind the AC voltage phase can make the peak of the backup voltage arrive slightly later than the AC voltage peak during switching, thereby avoiding excessive voltage after superposition.

[0058] Based on the above, a power supply method of a phase tracking emergency power supply includes the following steps:

[0059] S1: When the mains power is normal, the input switch DL1 is closed and the output switch DL2 is opened, the voltage input module 1 supplies power to the load, provides mains power, and charges the power storage module 5 through the AC / DC module 3; according to the regulations of the power system, the allowable voltage deviation range of 400V is ±5% of the rated voltage, that is, the allowable line voltage range is 380V-420V, and the range of 380V-420V belongs to the normal range of the mains power;

[0060] S2: The control unit 7 monitors the phase of the voltage input module 1, controls the output phase of the DC / AC module 6 to be the same as the output phase of the voltage input module 1, and the voltage amplitude of the DC / AC module 6 is greater than the output voltage amplitude of the mains voltage. Specifically, the voltage amplitude of the DC / AC module 6 is 1%-5% greater than the output voltage amplitude of the mains voltage; or when the mains voltage is close to the voltage upper limit (the voltage upper limit in this embodiment is 420V, specifically, when the mains voltage is equal to 99% of the voltage upper limit, the mains voltage is close to the voltage upper limit), the main strategy fails, and the backup strategy is started. The backup strategy is to adjust the output phase of the DC / AC module 6 to lag slightly behind the mains voltage phase, and in this embodiment, it lags by 5°-10°;

[0061] S3: When the mains power is abnormal (including but not limited to low voltage, voltage fluctuation, power supply interruption, etc.), the input switch DL1 is disconnected and the output switch DL2 is closed, and the load is powered by the power storage module 5 and the inverter.

[0062] More specifically, if Figure 5 As shown, the S2 specifically includes:

[0063] S21: Determine whether the voltage V1 of the voltage input module 1 is greater than the upper limit V of the phase voltage of the voltage input module 1 max , jump to S22, otherwise jump to S23;

[0064] S22: the control unit 7 adjusts the phase of the output voltage V2 of the DC / AC module 6 to ensure that the phase difference Δψ between V2 and V1 is ≥ ψ; wherein ψ is a positive phase angle close to 0, and the value of ψ is 5°;

[0065] S23: Determine whether the voltage V1 of the voltage input module 1 is less than the lower limit V of the phase voltage of the voltage input module 1 min , jump to S22, otherwise jump to S24;

[0066] S24: Determine whether the output voltage V2 of the DC / AC module 6 is greater than or equal to V1+ΔV, where ΔV is the margin of the voltage difference; if yes, jump to S25; otherwise, jump to S26;

[0067] S25: The control unit 7 adjusts the phase of the output voltage V2 of the DC / AC module 6 to ensure that ψ>Δψ≥0;

[0068] S26: adjust and increase V2;

[0069] S27: Determine whether JSQ is greater than N, where N indicates that the DC / AC module 6 needs N cycles to adjust the voltage to the expected value, and JSQ is a cycle counter for determining the voltage V2 of the DC / AC module 6; if yes, jump to S28, otherwise jump to S21;

[0070] S28: Start the backup adjustment to make V2 phase lag and ensure Δψ≥ψ.

[0071] This embodiment controls the output voltage of the DC / AC module to track the AC power supply, so that its voltage phase is the same as the AC power supply, and the voltage amplitude is slightly larger than the hot standby state of the AC power supply, so that seamless switching can be achieved; this embodiment is an application of the anti-power swing mode, and the power switching action preparation begins when the voltage drops sharply.

[0072] In the specification provided by the present invention, a large number of specific details are described; however, it can be understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this specification.

[0073] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof; however, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims below, inventive aspects lie in less than all of the features of a single embodiment disclosed above. Therefore, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the present invention.

[0074] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0075] It should be noted that the above embodiments illustrate the present invention rather than limit the present invention, and those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation to the claims.

[0076] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

[0077] The preferred embodiments of the present application are described in detail above in conjunction with the accompanying drawings; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the various possible combinations of this application will not be described separately.

[0079] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A power supply method for a phase tracking emergency power supply, characterized in that: The steps include: The voltage input module (1) is used to input the mains voltage; the voltage input module (1) is provided with an input switch; An AC / DC module (3) is connected to the voltage input module (1) and is used to convert alternating current into direct current; and the AC / DC module (3) is arranged in parallel with the input switch; Power storage module (5): connected to the AC / DC module (3), the AC / DC module (3) charges the power storage module (5); A DC / AC module (6) connected to the power storage module (5) and used for converting direct current into alternating current; The output end of the DC / AC module (6) is connected to an output switch; a control unit (7) is embedded in the DC / AC module (6); A comparison module (8) is connected to the control unit (7) and the voltage input module (1) and is used to compare the phase of the voltage of the voltage input module (1); the control unit (7) controls the output phase of the comparison module (8) to be the same as the output phase of the voltage input module (1); S1: When the mains power is normal, the input switch is closed and the output switch is opened, the voltage input module (1) supplies power to the load, and the power storage module (5) is charged through the AC / DC module (3); S2: the control unit (7) monitors the phase of the voltage input module (1) and controls the output phase of the DC / AC module (6) to be the same as the output phase of the voltage input module (1); or when the mains voltage is equal to 99% of the voltage upper limit, the output phase of the DC / AC module (6) is adjusted to lag behind the output phase of the voltage input module (1); S21: Determine whether the voltage V1 of the voltage input module (1) is greater than the upper limit V of the phase voltage of the voltage input module (1) max , jump to S22, otherwise jump to S23; S22: the control unit (7) adjusts the phase of the output voltage V2 of the DC / AC module (6) to ensure that the phase difference Δψ between V2 and V1 is ≥ ψ; wherein ψ is a positive phase angle close to 0 and has a value of 1°-5°; S23: Determine whether the voltage V1 of the voltage input module (1) is less than the lower limit V of the phase voltage of the voltage input module (1) min , jump to S22, otherwise jump to S24; S24: Determine whether the output voltage V2 of the DC / AC module (6) is greater than or equal to V1+ΔV, where ΔV is the margin of the voltage difference; if so, adjust to S25; otherwise, jump to S26; S25: the control unit (7) adjusts the phase of the output voltage V2 of the DC / AC module (6) to ensure that ψ>Δψ≥0; S26: adjust and increase V2; S27: Determine whether JSQ is greater than N, where N indicates that the inverter needs N cycles to adjust the voltage to the expected value, and JSQ is a cycle counter for determining the output voltage V2 of the DC / AC module (6); if yes, jump to S28; otherwise, jump to S21; S28: Start the standby adjustment to make V2 phase lag and ensure Δψ≥ψ; S3: When an abnormality occurs in the mains power, the input switch is opened and the output switch is closed, and the load is powered through the power storage module (5) and the DC / AC module (6).

2. A method for supplying power to a phase tracking emergency power supply according to claim 1, characterized in that: In S22, before the control unit (7) adjusts the phase of the output voltage V2 of the DC / AC module (6), an alarm output is first performed.

3. A phase tracking emergency power supply using the power supply method of a phase tracking emergency power supply according to claim 1 or 2, characterized in that: The AC / DC module (3) adopts a rectifier bridge, and a DC support capacitor (4) is arranged between the output ends of the rectifier bridge.

4. A phase tracking emergency power supply according to claim 3, characterized in that: The AC / DC module (3) adopts a battery charger, and at least one phase of the voltage input module (1) is connected to the AC / DC module (3).

5. A phase tracking emergency power supply according to claim 3, characterized in that: The input switch comprises an original power input switch DL1 , and a thyristor is arranged in parallel on the original power input switch DL1 .

6. A phase tracking emergency power supply according to claim 5, characterized in that: The thyristor is a single-phase thyristor (2) or a bidirectional thyristor (10).

7. A phase tracking emergency power supply according to claim 5, characterized in that: The output switch includes an input switch DL2 of a backup power supply, a thyristor is arranged in parallel with the input switch DL2 of the backup power supply, or the output switch includes a thyristor.

8. A phase tracking emergency power supply according to claim 7, characterized in that: The original power input switch DL1 and the backup power input switch DL2 are both fast-opening switches.

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