Multi-interface AC / DC standby power device and control method thereof

Abstract

The invention relates to a multi-interface alternating-current and direct-current standby power device and a control method thereof. The multi-interface alternating-current and direct-current standby power device comprises a direct-current bus, the output side of the standby power device is provided with a plurality of direct current standby power ports, and the plurality of direct current standby power ports are respectively connected with a direct current bus through independent DC / DC converters; the input side of the standby power device is provided with a plurality of different types of standby power batteries, an alternating current standby power supply and a photovoltaic group string; the standby battery and the photovoltaic group string are connected with the direct current bus through the corresponding DC / DC converter; and the AC standby power supply is connected with the DC bus through the DC / AC converter. Compared with the prior art, the power supply access type of the direct-current standby power is expanded, the service life of the standby power equipment is prolonged, and the defect that the voltage of the original direct-current standby power system is limited by the voltage of the battery is overcome.

Description

A multi-interface AC / DC backup power device and its control method Technical Field

[0001] This invention relates to the field of backup power technology, and in particular to a multi-interface AC / DC backup power device and its control method. Background Technology

[0002] Backup power supplies are an indispensable part of my country's telecommunications and power industries, widely distributed across various locations nationwide. With the rapid development of my country's economy, the comprehensive coverage of communication and power systems, as well as the safety and reliability of communication networks and DC relay protection devices, are becoming increasingly important. The number of backup power supplies in DC systems is growing significantly every year. Traditional DC backup power uses batteries directly as DC power sources, but due to their limited capacity, they can only handle short-term emergency use. Exceeding the battery's limits will cause power outages, leading to communication interruptions, damage, and other risks. Furthermore, the lead-acid batteries currently used for backup power generally have a voltage of 12V or 48V. This limitation restricts the voltage range that current DC backup power equipment can provide, failing to meet the needs of complex scenarios and diverse equipment. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a multi-interface AC / DC backup power device and its control method.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] As a first aspect of the present invention, a multi-interface AC / DC backup power device is provided, wherein the backup power device includes a DC bus.

[0006] The output side of the backup power device is provided with several DC backup power ports, and each of the multiple DC backup power ports is connected to the DC bus through an independent DC / DC converter;

[0007] The input side of the backup power unit includes various types of backup batteries, AC backup power supplies, and photovoltaic strings;

[0008] The backup battery and photovoltaic string are connected to the DC bus via corresponding DC / DC converters; the AC backup power supply is connected to the DC bus via a DC / AC converter.

[0009] As a preferred technical solution, the output voltage of the DC / DC converter corresponding to each of the DC backup power ports is different.

[0010] As a preferred technical solution, the DC / AC converter corresponding to the DC backup power port includes a DC / DC converter with adjustable output voltage using a Buck-Boost circuit.

[0011] As a preferred technical solution, the backup battery includes one or more of lead-acid batteries, lithium batteries, flywheel batteries, and hydrogen batteries.

[0012] As a preferred technical solution, various types of backup batteries are connected to the DC bus via bidirectional DC / DC converters.

[0013] As a preferred technical solution, the AC backup power supply includes a single-phase 220V AC backup power supply and an AC backup power supply including three-phase 380V AC backup power supplies.

[0014] As a preferred technical solution, the DC / AC converter corresponding to the AC backup power supply is a DC / AC converter with a back-to-back full-bridge rectifier topology.

[0015] As a preferred technical solution, a surge protector is installed between the photovoltaic string and the DC bus.

[0016] As a second aspect of the present invention, a control method for the multi-interface AC / DC backup power device as described above is provided, the method steps including:

[0017] When the backup power supply voltage is less than the set threshold, the backup power device only uses the backup battery for power supply; disconnect the DC bus from the AC backup power supply and photovoltaic string, and maintain the voltage on the DC bus at 48V by controlling the DC / DC converter corresponding to the backup battery;

[0018] When the backup power supply voltage is greater than the set threshold, connect the AC backup power supply to the DC bus; disconnect the power supply battery whose output voltage is lower than the bus voltage from the backup power battery to the DC bus, and maintain the voltage on the DC bus at 220V.

[0019] When the backup power unit is idle, it charges each backup battery through the AC backup power supply and the photovoltaic string.

[0020] As a preferred technical solution, the method monitors the remaining battery capacity of each backup battery when the backup power supply voltage is less than a set threshold.

[0021] When the remaining battery capacity of the backup battery is lower than the set threshold, its connection to the DC bus is disconnected; when the remaining capacity of all backup batteries is lower than the set threshold, the AC backup power supply is connected to the DC bus to provide backup power.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The backup power device provided by the present invention expands the types of DC backup power sources. External backup power sources can be connected through ACDC or DCDC modules, or through DCDC modules to connect to various batteries including lithium batteries, flywheels, hydrogen batteries, etc., providing the equipment with backup power sources with various voltage output specifications, which effectively solves the defect of the original DC backup power system where the voltage is limited by the battery voltage.

[0024] 2) This invention designs a backup power device control method, which can rely solely on battery power to provide emergency power to the equipment and keep it running under normal circumstances. When the battery power is low, it can be switched off in time to reduce voltage fluctuations. When the battery is completely depleted, it can also be powered by an external AC backup power source to maintain the long-term operation of the equipment.

[0025] 3) When a higher backup voltage is required, the present invention can also provide 220V DC power through an additional lithium battery pack and an external AC backup power supply.

[0026] 4) This invention uses one end of the DC-DC converter as a backup power interface, and employs a DC / DC converter with adjustable output voltage via a Buck-Boost circuit to achieve adjustable port voltage, making it suitable for various backup power applications. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the structure of a multi-interface AC / DC backup power device according to the present invention;

[0028] The numbers in the diagram indicate: 1. DC bus, 2. DC backup power port, 3. Backup battery, 4. AC backup power supply, 5. Photovoltaic string. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] This invention provides a multi-interface AC / DC backup power device, as shown in Figure 1. The device comprises a DC bus 1, several DC backup power ports 2, various types of backup batteries 3, and corresponding DC / DC and DC / AC converters. The backup power device is connected to multiple DC backup power ports 2 on the output side via the DC bus 1 and a DC / DC converter. On the input side of the backup power device, it is connected to the backup batteries 3 via a bidirectional DC / DC converter, connected to an AC backup power source 4 via a DC / AC converter, and connected to a photovoltaic string 5 via a unidirectional DC / DC converter.

[0032] Specifically, the output voltages of each DC backup power port 2 are different. The output voltages of the corresponding DC / DC converters include 12V and 48V. There is also a DC / DC converter using a Buck-Boost circuit, whose DC backup power port voltage is adjustable and suitable for various backup power applications.

[0033] The backup battery 3 can be one or more of lead-acid batteries, lithium batteries, flywheel batteries, and hydrogen batteries. In this embodiment, the lead-acid battery provides 13.5V DC power, while the lithium battery pack can provide 624V high-voltage DC power.

[0034] Backup battery 3 uses a bidirectional DC / DC converter, which can achieve peak shaving of AC energy in idle time and AC interface, thereby improving the value of backup battery in idle state.

[0035] The AC backup power supply 4 includes a single-phase 220V AC backup power supply 4 and a three-phase 380V AC backup power supply 4. The DC / AC converter of the AC backup power supply 4 adopts a back-to-back full-bridge rectifier topology.

[0036] A surge protector is also installed between the photovoltaic string 5 and the DC bus 1 to prevent voltage fluctuations caused by lightning strikes from damaging the components in the low-voltage backup power equipment.

[0037] Example 2

[0038] As another embodiment of the present invention, this embodiment also provides a control method for the backup power device as described in Embodiment 1 above.

[0039] Under normal backup power requirements, only emergency power supply is needed for peripheral equipment of the communication and power systems. There is no need for a backup power device to provide power for extended periods or at high voltages; backup battery 3 alone is sufficient to meet the power demand. At this time, by controlling the voltage output to the DC bus by the DC / DC converter corresponding to backup battery 3, the voltage on DC bus 1 is maintained at 48V. The connection between DC bus 1 and the AC backup power supply 4 and the photovoltaic string 5 is disconnected to prevent voltage fluctuations. The DC backup power port 2 on the output side of the backup power device converts the 48V DC power on DC bus 1 to a corresponding output voltage via a DC / DC converter.

[0040] For chemical batteries, the output voltage will rapidly decrease when the remaining capacity is too low, especially for lead-acid and lithium batteries. Therefore, it is necessary to set a capacity threshold for each backup battery 3. When the remaining capacity of a backup battery 3 is lower than the set threshold, its connection to the DC bus 1 is disconnected to prevent it from affecting the voltage of the DC bus 1. When the remaining capacity of all backup batteries 3 is lower than the set threshold, the connection between the DC bus 1 and the AC backup power supply 4 is restarted, and power is supplied through the AC backup power supply 4.

[0041] When backup power equipment requires a higher voltage DC power supply, the voltage on DC bus 1 is maintained at 220V. Since the lead-acid battery's output voltage is too low, its power supply connection to DC bus 1 is disconnected, and AC backup power supply 4 is activated to provide power. Meanwhile, the adjustable voltage port of the DC / DC converter using a Buck-Boost circuit in DC backup power port 2 can output the corresponding voltage as needed.

[0042] Often, only emergency power supply is needed for peripheral equipment in communication and power systems, without the need for a backup power device to provide long-term or high-voltage power. The backup power device, using only backup battery 3, is sufficient to meet the power requirements. At this time, by controlling the voltage output to the DC bus by the DC / DC converter corresponding to backup battery 3, the voltage on DC bus 1 is maintained at 48V. The connection between DC bus 1 and the AC backup power supply 4 and the photovoltaic string 5 is disconnected to prevent voltage fluctuations. The DC backup power port on the output side of the backup power device converts the 48V DC power on DC bus 1 to the corresponding output voltage DC power through the DC / DC converter.

[0043] When the backup power unit is idle, it charges each backup battery 3 via AC backup power supply 4 and photovoltaic string 5. It can also utilize the backup batteries and AC interface to achieve peak shaving of AC energy, increasing the value of the backup batteries in idle states. However, its peak shaving capacity should not exceed 30% of its maximum capacity to avoid impacting the unit's backup power capability.

[0044] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A multi-interface AC / DC backup power device, characterized in that, The backup power device includes a DC bus (1); the output side of the backup power device is provided with several DC backup power ports (2), and the multiple DC backup power ports (2) are respectively connected to the DC bus (1) through independent DC / DC converters; the input side of the backup power device is provided with various types of backup batteries (3), AC backup power supply (4) and photovoltaic strings (5); the backup batteries (3) and photovoltaic strings (5) are connected to the DC bus (1) through corresponding DC / DC converters; the AC backup power supply (4) is connected to the DC bus (1) through a DC / AC converter.

2. The multi-interface AC / DC backup power device according to claim 1, characterized in that, The output voltage of the DC / DC converter corresponding to each of the DC backup power ports (2) is different.

3. The multi-interface AC / DC backup power device according to claim 1, characterized in that, The DC / AC converter corresponding to the DC backup power port (2) includes a DC / DC converter with adjustable output voltage using a Buck-Boost circuit.

4. A multi-interface AC / DC backup power device according to claim 1, characterized in that, The backup battery (3) includes one or more of lead-acid batteries, lithium batteries, flywheel batteries and hydrogen batteries.

5. A multi-interface AC / DC backup power device according to claim 1, characterized in that, The various types of backup batteries (3) are connected to the DC bus (1) via bidirectional DC / DC converters.

6. A multi-interface AC / DC backup power device according to claim 1, characterized in that, The AC backup power supply (4) includes a single-phase 220V AC backup power supply (4) and an AC backup power supply (4) including three-phase 380V AC backup power supplies (4).

7. A multi-interface AC / DC backup power device according to claim 1, characterized in that, The DC / AC converter corresponding to the AC backup power supply (4) is a DC / AC converter with a back-to-back full-bridge rectifier topology.

8. A multi-interface AC / DC backup power device according to claim 1, characterized in that, A surge protector is provided between the photovoltaic string (5) and the DC bus (1).

9. A control method for a multi-interface AC / DC backup power device as described in any one of claims 1-8, characterized in that, The method steps include: when the backup power supply voltage is less than the set threshold, the backup power device only uses the backup battery (3) for power supply; disconnect the DC bus (1) from the AC backup power supply (4) and the photovoltaic string (5), and maintain the voltage on the DC bus (1) at 48V by controlling the DC / DC converter corresponding to the backup battery (3); when the backup power supply voltage is greater than the set threshold, connect the AC backup power supply (4) to the DC bus (1); disconnect the power supply battery (3) whose output voltage is less than the bus voltage from the DC bus (1), and maintain the voltage on the DC bus (1) at 220V; when the backup power device is idle, the backup power device charges each backup battery (3) through the AC backup power supply (4) and the photovoltaic string (5).

10. The control method according to claim 9, characterized in that, The method monitors the remaining battery capacity of each backup battery (3) when the backup power supply voltage is less than the set threshold: when the remaining battery capacity of the backup battery (3) is lower than the set threshold, it disconnects its connection with the DC bus (1); when the remaining capacity of all backup batteries (3) is lower than the set threshold, it connects the AC backup power supply (4) to the DC bus (1) and provides backup power supply through the AC backup power supply (4).

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