An uninterruptible power supply device

Abstract

The application belongs to the technical field of power supply, and particularly relates to an uninterruptible power supply device. An online UPS has large online loss and high cost, and a backup UPS has slow response speed and system capacity is restricted by DC side energy storage elements. The application provides an uninterruptible power supply device, which comprises a first fast switch, a first bidirectional converter, an energy storage unit, a second bidirectional converter and a second fast switch connected in sequence, the energy storage unit is connected in parallel between the first bidirectional converter and the second bidirectional converter, and the first fast switch, a bypass switch and the second fast switch are connected in sequence. The problem that the UPS cannot stably supply power to the load under capacity constraint when the main power supply fails for a long time is effectively solved, the system capacity is expanded on the basis of not increasing the energy storage cost of a single UPS, transient power quality problems such as voltage sag are considered, and high-quality stable power supply is provided for the load.

Description

Technical Field

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

[0002] UPS (Uninterruptible Power System) is a constant voltage and frequency power supply containing energy storage devices and with an inverter as its main component. It is primarily used to provide uninterrupted power to single computers, computer network systems, or other power electronic equipment.

[0003] With the development of high technology and the transformation of emerging industries in my country, higher requirements have been placed on power quality in fields such as industrial production, medical and health care, and IT communications. Voltage sags and short-term interruptions are the most common power quality problems in production and daily life. Currently, the most widely used solutions are dynamic voltage restorers (DVRs) and uninterruptible power supplies (UPS).

[0004] Among them, series-type DVRs have limited voltage compensation depth and cannot effectively provide stable power to the load when the main power supply voltage drops significantly or when a short-term interruption occurs; parallel-type DVR systems are limited by the DC-side energy storage components and can only provide power for short periods; online UPS systems have high online losses and high costs; and standby UPS systems have slow response speeds that cannot meet the requirements of sensitive loads, and their system capacity is also limited by the DC-side energy storage components. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] In view of the problems that online UPS has large online losses and high costs, and standby UPS has slow response speed and system capacity is limited by DC side energy storage components, this application provides an uninterruptible power supply device.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, this application provides an uninterruptible power supply device, comprising a first fast switch, a first bidirectional converter, an energy storage unit, a second bidirectional converter, and a second fast switch connected in sequence. The energy storage unit is connected in parallel between the first bidirectional converter and the second bidirectional converter. The first fast switch, a bypass switch, and the second fast switch are connected in sequence.

[0009] Another embodiment provided by this application is as follows: one end of the first fast switch is connected to the first main power supply through the first line, and the other end of the first fast switch is connected to the first load through the first line; one end of the second fast switch is connected to the second main power supply through the second line, and the other end of the second fast switch is connected to the second load through the second line.

[0010] Another embodiment provided in this application is as follows: the AC side of the first bidirectional converter is connected in parallel to the first line, and the AC side of the second bidirectional converter is connected in parallel to the second line; the first bidirectional converter and the second bidirectional converter share a common DC bus, and the energy storage unit is connected in parallel to the common DC bus.

[0011] Another embodiment provided in this application is that the bypass switch is connected in parallel to the AC output side of the first bidirectional converter and the AC output side of the second bidirectional converter.

[0012] Another embodiment provided in this application is as follows: the first bidirectional converter is a three-phase converter or a single-phase converter; the second bidirectional converter is a three-phase converter or a single-phase converter; the topology of the first bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology; the topology of the second bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology.

[0013] Another embodiment provided in this application is that the energy storage unit is a battery or a supercapacitor.

[0014] Another embodiment provided in this application is as follows: the first fast switch is a fast circuit breaker, a relay, or an anti-parallel thyristor; the second fast switch is a fast circuit breaker, a relay, or an anti-parallel thyristor.

[0015] Another embodiment provided in this application is that the uninterruptible power supply device operates under the following conditions: normal operation of the first main power supply and the second main power supply, failure of the first main power supply or failure of the second main power supply, simultaneous failure of the first main power supply and the second main power supply, or voltage sag of the first main power supply or voltage sag of the second main power supply.

[0016] Another embodiment provided in this application is that the uninterruptible power supply device includes a harmonic mitigation module.

[0017] Another implementation method provided in this application is: the uninterruptible power supply device includes ten working switching modes.

[0018] 3. Beneficial effects

[0019] Compared with the prior art, the advantages of the uninterruptible power supply device provided in this application are as follows:

[0020] The uninterruptible power supply device provided in this application is a dual-input dual-output offline uninterruptible power supply (UPS) device that maintains a stable and high-quality power supply for dual loads.

[0021] The uninterruptible power supply device provided in this application can provide high-quality and stable power supply to the load when the main power supply fails or transient power quality problems such as voltage dips occur.

[0022] The uninterruptible power supply device provided in this application enables stable UPS power supply in the event of main power failure or transient power quality problems such as voltage dips.

[0023] The uninterruptible power supply device provided in this application effectively solves the problem that the UPS cannot provide stable power to the load under capacity constraints when the main power supply fails for a long time. It expands the system capacity without increasing the energy storage cost of a single UPS, and takes into account transient power quality issues such as voltage dips, so as to provide high-quality and stable power supply to the load.

[0024] The uninterruptible power supply device provided in this application enables a stable power supply under system capacity constraints when the main power supply fails for an extended period of time.

[0025] The uninterruptible power supply device provided in this application expands the overall system capacity without increasing the energy storage cost of a single UPS.

[0026] The uninterruptible power supply device provided in this application avoids the converter from being under load for a long time, reduces the heat loss of the converter, and effectively reduces costs compared with a standby UPS of the same capacity.

[0027] The uninterruptible power supply device provided in this application improves the load power supply quality when transient power quality problems such as voltage dips occur in the main power supply.

[0028] The uninterruptible power supply device provided in this application allows for the optional activation or deactivation of harmonic mitigation function when the main power supply is operating normally, thereby improving the power quality of the load without adding additional power management equipment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the uninterruptible power supply device structure of this application;

[0030] Figure 2 This is a schematic diagram of the working process of the uninterruptible power supply device of this application. Detailed Implementation

[0031] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0032] The terms "first" or "second" in this application are used only to distinguish the components, which have the same function and structure.

[0033] See Figures 1-2 This application provides an uninterruptible power supply device, including a first fast switch 1, a first bidirectional converter 2, an energy storage unit 3, a second bidirectional converter 4, and a second fast switch 5 connected in sequence. The energy storage unit 3 is connected in parallel between the first bidirectional converter 2 and the second bidirectional converter 4. The first fast switch 1, the bypass switch 6, and the second fast switch 5 are connected in sequence.

[0034] Furthermore, one end of the first fast switch 1 is connected to the first main power supply 7 via the first line, and the other end of the first fast switch 1 is connected to the first load 8 via the first line; one end of the second fast switch 5 is connected to the second main power supply 9 via the second line, and the other end of the second fast switch 5 is connected to the second load 10 via the second line.

[0035] Furthermore, the AC side of the first bidirectional converter 2 is connected in parallel to the first line, and the AC side of the second bidirectional converter 4 is connected in parallel to the second line; the first bidirectional converter 2 and the second bidirectional converter 4 share a common DC bus, and the energy storage unit 3 is connected in parallel to the common DC bus.

[0036] Furthermore, the bypass switch 6 is connected in parallel to the AC output side of the first bidirectional converter 2 and the AC output side of the second bidirectional converter 4.

[0037] The first fast switch 1 is connected in series to the first line, and the second fast switch 5 is connected in series to the second line, for quickly disconnecting or connecting the main power supply on the corresponding line.

[0038] The AC side of the first bidirectional converter 2 is connected in parallel to the first line, and the AC side of the second bidirectional converter 4 is connected in parallel to the second line. The energy storage unit 3 is connected in parallel to the common DC bus of the first bidirectional converter 2 and the second bidirectional converter 4.

[0039] Furthermore, the first bidirectional converter 2 is a three-phase converter or a single-phase converter; the second bidirectional converter 4 is a three-phase converter or a single-phase converter; the topology of the first bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology; the topology of the second bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology.

[0040] Furthermore, the energy storage unit 3 is an energy storage device such as a battery or supercapacitor that has the ability to output DC voltage, and its corresponding control circuit.

[0041] Furthermore, the first fast switch is a high-speed switching device such as a fast circuit breaker, a relay, or an anti-parallel thyristor; the second fast switch is a high-speed switching device such as a fast circuit breaker, a relay, or an anti-parallel thyristor.

[0042] Furthermore, the uninterruptible power supply device operates under the following conditions: normal operation of the first main power supply 7 and the second main power supply 9; failure of the first main power supply 7 or the second main power supply 9; simultaneous failure of the first main power supply 7 and the second main power supply 9; or voltage sag of the first main power supply 7 or the second main power supply 9.

[0043] Furthermore, the uninterruptible power supply device includes a harmonic mitigation module.

[0044] Under normal operating conditions, the main power supply (including the first main power supply 7 and the second main power supply 9, collectively referred to as the main power supply) operates as follows: The uninterruptible power supply (UPS) fast switch remains in the conducting state, allowing the UPS to charge the internal energy storage unit 3; the bypass switch 6 remains in the off state, and the main power supply powers the load. Under normal operating conditions of the main power supply, it is possible to choose whether to activate the harmonic mitigation module. If activated, one converter operates in constant DC voltage mode, while the other converter acts as a current source to mitigate harmonic currents in the main line on that side.

[0045] In other words, one of the two converters operates in constant voltage or constant current mode to charge the energy storage unit, while the other is in hot standby mode; after the energy storage unit 3 is fully charged, both converters enter hot standby mode.

[0046] Two converters normally operate under two conditions:

[0047] ① One unit charges energy storage unit 3, and the other is in hot standby mode; after charging is completed, both enter hot standby mode.

[0048] ② One unit is used to maintain the DC side voltage, and the other unit is used as a current source to compensate for the harmonic current on the main line of the converter.

[0049] Single-sided main power supply failure. The fast switch on the faulty side of the uninterruptible power supply (UPS) is turned off, while the fast switch on the non-faulty side remains on, and the load on the faulty side is powered by the main power supply on the non-faulty side.

[0050] Dual-side main power supply failure scenario. The uninterruptible power supply (UPS) is shut down via dual-side fast switches, the UPS is offline with load applied, and the bypass switch remains off.

[0051] In the event of a transient power quality problem such as a voltage sag in any main power supply, the fast switch on the problematic side of the uninterruptible power supply (UPS) will turn off, while the fast switch on the non-problem side will remain on, supplying power to the load on the problematic side from the main power supply on the non-problem side.

[0052] Specifically, during the normal operation of the main power supply—charging of energy storage unit 3—the fast switch remains on. One of the main converters, 2 and 4, operates in constant DC voltage or constant current mode to charge the energy storage unit 3 at constant voltage or constant current, while the other is in hot standby mode. Once the energy storage unit 3 is fully charged, both main converters are in hot standby mode, the bypass switch 6 remains off, and the main power supply powers the load.

[0053] The main power supply operates normally under harmonic control conditions. The fast switch remains in the on state. One of the first bidirectional converter 2 and the second bidirectional converter 4 operates in constant DC voltage mode to provide DC voltage to the energy storage unit 3, while the other acts as a current source to control the harmonic current of the main line on this side. The bypass switch remains in the off state, and the load is powered by the main power supply.

[0054] In the case of a single-sided main power supply failure, the fast switch on the non-faulty side remains on while the fast switch on the faulty side is off. The converter on the faulty side operates in voltage source mode and tracks the main power supply on the non-faulty side under load. After synchronization, the bypass switch 6 is closed, and the main power supply on the non-faulty side supplies power to the load on the faulty side. The converter on the faulty side switches to hot standby mode, and the converter on the non-faulty side charges the energy storage unit 3. After charging is completed, it switches to hot standby mode.

[0055] In the event of a dual-side main power supply failure, the first fast switch 1 and the second fast switch 5 are turned off, the first bidirectional converter 2 and the second bidirectional converter 4 operate in voltage source mode, supplying power to the first load 8 and the second load 10 respectively; the voltage at the common DC bus of the first bidirectional converter 2 and the second bidirectional converter 4 is maintained by the energy storage unit 3; and the bypass switch 6 remains off.

[0056] In the event of a power quality problem such as a voltage sag in any of the main power supplies, the fast switch on the non-problem side remains on while the fast switch on the problem side is off. The converter on the problem side operates in voltage source mode, tracks the main power supply on the non-problem side under load, and closes the bypass switch 6 after synchronization. The main power supply on the non-problem side supplies power to the load on the problem side, and the converter on the problem side switches to hot standby mode. The converter on the non-problem side charges the energy storage unit 3, and switches to hot standby mode after charging is completed.

[0057] Furthermore, the uninterruptible power supply device includes ten operating switching modes.

[0058] Mode 1: Switching from charging mode of energy storage unit 3 under normal main power supply operation to harmonic mitigation mode; Mode 2: Switching from harmonic mitigation mode of normal main power supply operation to charging mode of energy storage unit 3; Mode 3: Switching from normal main power supply operation to single-sided main power supply failure mode; Mode 4: Switching from single-sided main power supply failure mode to normal main power supply operation; Mode 5: Switching from normal main power supply operation to double-sided main power supply failure mode; Mode 6: Switching from double-sided main power supply failure mode to normal main power supply operation; Mode 7: Switching from single-sided main power supply failure mode to double-sided main power supply failure mode; Mode 8: Switching from double-sided main power supply failure mode to single-sided main power supply failure mode; Mode 9: Switching from normal main power supply operation to transient power quality issues such as voltage dips in any main power supply mode; Mode 10: Switching from transient power quality issues such as voltage dips in any main power supply mode to normal main power supply operation.

[0059] Specifically, in the operation switching mode ①, the energy storage unit charging mode under normal main power supply operation is switched to harmonic mitigation mode. The first fast switch 1 and the second fast switch 5 are kept on. One of the first bidirectional converter 2 and the second bidirectional converter 4 is in constant DC voltage mode to provide DC voltage for the energy storage unit 3, while the other is activated to perform harmonic current detection and harmonic current mitigation functions. The bypass switch 6 is kept off, and the entire uninterruptible power supply device enters the normal main power supply operation mode - harmonic mitigation mode.

[0060] The operation switching mode ② switches from harmonic mitigation mode under normal main power supply operation to energy storage unit charging mode. The first bidirectional converter 2 or the second bidirectional converter 4 turns off the harmonic current detection and harmonic current mitigation functions. One of them operates in constant DC voltage mode or constant current mode to charge the energy storage unit 3 with constant voltage or constant current, while the other is in hot standby mode. When the energy storage unit 3 is fully charged, both main converters are in hot standby mode, and the entire uninterruptible power supply device enters the normal main power supply operation - energy storage unit charging mode.

[0061] In the operation switching mode ③, when the main power supply is working normally, it switches to a single-side main power supply failure mode. The fast switch on the failure side switches from on to off. The converter on the failure side switches from any operating condition under normal main power supply conditions to voltage source mode. The load on the failure side tracks the main power supply on the non-failure side. After synchronization, the bypass switch 6 is closed, and the main power supply on the non-failure side supplies power to the load on the failure side at the same time. The converter on the failure side switches from voltage source mode to hot standby mode. The converter on the non-failure side charges the energy storage unit 3. After charging is completed, the converter on the non-failure side switches to hot standby mode, and the entire uninterruptible power supply enters a single-side main power supply failure mode.

[0062] In the operation switching mode ④, when a single-side main power supply fails, the main power supply returns to normal operation. By turning off the bypass switch 6, the original faulty side converter changes from hot standby to voltage source mode, enabling the original faulty side load to track the original faulty side main power supply. After synchronization, the original faulty side fast switch is turned on, and the original faulty side converter changes from voltage source mode to charging the energy storage unit. The entire device then enters the normal operation mode of the main power supply.

[0063] In the operation switching mode ⑤, when the main power supply is working normally and then switches to a dual-side main power supply failure mode, the first fast switch 1 and the second fast switch 5 switch from being on to being off, and the first bidirectional converter 2 and the second bidirectional converter 4 switch from either operating condition under normal main power supply conditions to voltage source mode, and the entire device enters a dual-side main power supply failure mode.

[0064] In the aforementioned working switching mode ⑥, when both main power supplies fail, the system switches to normal operation of the main power supply. The first bidirectional converter 2, with the first load 8, tracks the first main power supply 7, and the second bidirectional converter 4, with the second load 10, tracks the second main power supply 9. After synchronization, the first fast switch 1 and the second fast switch 5 switch from off to on. The first bidirectional converter 2 and the second bidirectional converter 4 switch from voltage source mode to energy storage unit charging mode under normal operation of the main power supply, and the entire device enters normal operation of the main power supply.

[0065] In the aforementioned working switching mode ⑦, the single-sided main power supply failure situation is switched to the dual-sided main power supply failure situation. The fast switch on the original non-faulty side is switched from being on to being off, the bypass switch 6 is switched from being on to being off, the bidirectional converter on the original non-faulty side is switched from the energy storage unit charging mode or hot standby state to the voltage source mode, and the entire device enters the dual-sided main power supply failure situation.

[0066] In the aforementioned working switching mode ⑧, the dual-side main power supply failure situation is switched to the single-side main power supply failure situation. The first bidirectional converter 2 and the second bidirectional converter 4 track the main power supply on the fault recovery side under load. After the tracking synchronization is completed, the fast switch on the fault recovery side is switched from off to on, and the bypass switch 6 is switched from off to on. The entire device then enters the single-side main power supply failure situation.

[0067] In the aforementioned working switching mode ⑨, when the main power supply is operating normally and a transient power quality problem such as a voltage sag occurs in any main power supply, the problem-side fast switch changes from on to off. The problem-side converter changes from any operating condition under normal main power supply conditions to voltage source mode, enabling the problem-side load to track the non-problem-side main power supply. After synchronization, the bypass switch 6 is closed, and the non-problem-side main power supply simultaneously supplies power to the problem-side load. The problem-side converter changes from voltage source mode to hot standby mode, and the non-problem-side converter charges the energy storage unit 3. After charging is completed, the non-problem-side converter changes to hot standby mode, and the entire uninterruptible power supply unit enters a transient power quality problem situation where a voltage sag occurs in any main power supply.

[0068] In the aforementioned working switching mode ⑩, if any main power supply experiences a transient power quality problem such as a voltage dip, the system switches to normal main power supply operation. Bypass switch 6 is turned off, and the original problem-side converter switches from hot standby mode to voltage source mode, enabling the original problem-side load to track the original problem-side main power supply. After synchronization, the original problem-side fast switch is turned on, and the original problem-side converter switches from voltage source mode to charging the energy storage unit. The entire device then enters normal main power supply operation mode.

[0069] Although this application has been described above with reference to specific embodiments, those skilled in the art will understand that many modifications can be made to the configurations and details disclosed in this application within the principles and scope of the disclosure. The scope of protection of this application is determined by the appended claims, and the claims are intended to cover all modifications included in the literal meaning or scope of equivalents of the technical features in the claims.

Claims

1. An uninterruptible power supply device, characterized in that: It includes a first fast switch, a first bidirectional converter, an energy storage unit, a second bidirectional converter, and a second fast switch connected in sequence. The energy storage unit is connected in parallel between the first bidirectional converter and the second bidirectional converter. The first fast switch, a bypass switch, and the second fast switch are connected in sequence. One end of the first fast switch is connected to the first main power supply via the first line, and the other end of the first fast switch is connected to the first load via the first line; one end of the second fast switch is connected to the second main power supply via the second line, and the other end of the second fast switch is connected to the second load via the second line. The AC side of the first bidirectional converter is connected in parallel to the first line, and the AC side of the second bidirectional converter is connected in parallel to the second line; the first bidirectional converter and the second bidirectional converter share a common DC bus, and the energy storage unit is connected in parallel to the common DC bus; The bypass switch is connected in parallel to the AC output side of the first bidirectional converter and the AC output side of the second bidirectional converter.

2. The uninterruptible power supply device as described in claim 1, characterized in that: The first bidirectional converter is a three-phase converter or a single-phase converter; the second bidirectional converter is a three-phase converter or a single-phase converter; the topology of the first bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology; the topology of the second bidirectional converter is a two-level topology, a three-level topology, or a multi-level topology.

3. The uninterruptible power supply device as described in claim 2, characterized in that: The energy storage unit is a battery or a supercapacitor.

4. The uninterruptible power supply device as described in claim 2, characterized in that: The first fast switch is a fast circuit breaker, a relay, or an anti-parallel thyristor; the second fast switch is a fast circuit breaker, a relay, or an anti-parallel thyristor.

5. The uninterruptible power supply device as described in claim 4, characterized in that: The uninterruptible power supply device operates under the following conditions: normal operation of the first main power supply and the second main power supply, failure of the first main power supply or the second main power supply, simultaneous failure of the first main power supply and the second main power supply, or voltage dip of the first main power supply or voltage dip of the second main power supply.

6. The uninterruptible power supply device as described in claim 5, characterized in that: The uninterruptible power supply device includes a harmonic mitigation module.

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