An uninterruptible power supply power switching circuit

Abstract

The utility model relates to an uninterrupted power supply power supply switching circuit, including photovoltaic system and double power conversion switch, the communication end of double power conversion switch connects the communication end of uninterrupted power supply, is used for reading the output voltage of uninterrupted power supply, the first input of double power conversion switch connects photovoltaic power supply system's output, and the second input connects external power supply end, and the input of uninterrupted power supply is connected to the output, double power conversion switch is configured as the output voltage of uninterrupted power supply is less than preset voltage value. In the utility model, through intelligent switching function, the circuit can dynamically adjust the power supply source according to the actual situation of photovoltaic power supply system and external power supply end, ensure the stable power supply of uninterrupted power supply and the normal operation of load equipment. This dynamic adjustment ability greatly improves the reliability and stability of power supply.

Description

Technical Field

[0001] This utility model relates to the field of power supply, and in particular to an uninterruptible power supply switching circuit. Background Technology

[0002] Photovoltaic power supply systems, with their advantages of being clean, environmentally friendly, and having low carbon emissions, are increasingly being applied to uninterruptible power supply (UPS) systems. Traditional UPS systems primarily rely on the external power grid and battery banks working together to provide power. When the power grid is normal, the rectifier charges the batteries, and when the grid is interrupted, it switches to battery discharge mode. However, such systems have the following drawbacks:

[0003] The reliance on a single energy source, particularly the traditional power grid, has led to persistently high carbon emissions, contradicting the demands of a green energy transition. While photovoltaic (PV) power generation can effectively alleviate this problem, current technologies lack intelligent design in their switching mechanisms between PV and the grid. This can result in power outages due to switching delays during periods of fluctuating sunlight or darkness at night, affecting the continuity of operation of load equipment.

[0004] Imbalance between battery utilization and lifespan: In conventional UPS systems, batteries are in a float charge state for extended periods, only discharging briefly during grid failures. This leads to accelerated crystallization and aging of the battery's active materials, requiring replacement every 3-5 years, resulting in resource waste and increased maintenance costs. Although photovoltaic systems can theoretically increase battery charge / discharge frequency through daytime charging, the coordinated control strategy for photovoltaic input and grid switching in existing topologies is not yet perfect, making dynamic optimization of the battery charge / discharge cycle impossible.

[0005] To address the aforementioned issues, there is an urgent need for an uninterruptible power supply switching circuit that can dynamically adapt to the fluctuation characteristics of photovoltaic power supply, achieve seamless switching between photovoltaic and external power sources, and optimize battery utilization, so as to balance environmental friendliness, economy, and system reliability. Utility Model Content

[0006] In view of this, the present invention aims to propose an uninterruptible power supply switching circuit to solve the problems in the prior art.

[0007] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0008] This utility model proposes an uninterruptible power supply switching circuit, including a photovoltaic system and a dual power transfer switch;

[0009] The communication terminal of the dual power supply transfer switch is connected to the communication terminal of the uninterruptible power supply (UPS) for reading the output voltage of the UPS.

[0010] The dual power supply transfer switch is configured such that its first input terminal is connected to the output terminal of the photovoltaic power supply system, its second input terminal is connected to the external power supply terminal, and its output terminal is connected to the input terminal of the uninterruptible power supply (UPS). The dual power supply transfer switch is configured such that when the output voltage of the UPS is less than a preset voltage value, it connects the external power supply terminal and the UPS, and disconnects the output terminal of the photovoltaic power supply system from the UPS. Conversely, it is configured such that when the output voltage of the UPS is greater than a preset voltage value, it connects the output terminal of the photovoltaic power supply system to the UPS, and disconnects the external power supply terminal from the UPS.

[0011] Furthermore, the photovoltaic power supply system includes photovoltaic modules and a controller;

[0012] The controller includes at least an input terminal and an output terminal;

[0013] The output terminal of the photovoltaic module is connected to the input terminal of the controller;

[0014] The output of the controller is connected to the first input of the dual power transfer switch.

[0015] Furthermore, the controller is an MPPT controller that supports battery-free mode.

[0016] Furthermore, the photovoltaic power supply system also includes an overvoltage protection circuit;

[0017] The overvoltage protection circuit includes a first fuse, a second fuse, a first button, a second button, and a contactor;

[0018] The controller is also provided with normally closed contacts and normally open contacts;

[0019] The controller's output terminals include at least a first output terminal and a second output terminal;

[0020] The first output terminal of the controller is connected to one end of the second fuse, the other end of the second fuse is connected to one end of the normally closed contact of the controller, the other end of the normally closed contact of the controller is connected to one end of the first button, the other end of the first button is connected to one end of the second button, one end of the normally open auxiliary contact of the contactor, and one end of the normally open contact of the controller; the other end of the second button, the other end of the normally open auxiliary contact of the contactor, and the other end of the normally open contact of the controller are respectively connected to one end of the drive coil of the contactor, the other end of the drive coil of the contactor is connected to one end of the first fuse, and the other end of the first fuse is connected to the second output terminal of the controller.

[0021] The first input terminal of the dual power supply transfer switch includes at least a first interface and a second interface;

[0022] The first output terminal of the controller is connected to one end of the first normally open main contact of the contactor, and the other end of the first normally open main contact of the contactor is connected to the first interface of the first input terminal of the dual power supply transfer switch.

[0023] The second output terminal of the controller is connected to one end of the second normally open main contact of the contactor, and the other end of the second normally open main contact of the contactor is connected to the second interface of the first input terminal of the dual power supply transfer switch.

[0024] Furthermore, the photovoltaic power supply system also includes a circuit breaker;

[0025] The output of the controller is connected to one end of the circuit breaker, and the other end of the circuit breaker is connected to the first input of the dual power transfer switch.

[0026] Furthermore, the preset voltage value ranges from DC 380V to DC 500V.

[0027] Compared with the prior art, this utility model has the following advantages:

[0028] In this invention, the circuit can dynamically adjust the power supply source according to the real-time usage of the uninterruptible power supply (UPS) through the automatic switching function of the dual power supply transfer switch, ensuring stable power supply and normal operation of the load equipment. This dynamic adjustment capability greatly improves the reliability and stability of the power supply.

[0029] Furthermore, this circuit fully utilizes the renewable energy advantages of photovoltaic systems, reducing reliance on the traditional power grid. Simultaneously, the uninterruptible power supply (UPS) acts as a buffer, alleviating the charging and discharging stress on the battery and extending its lifespan. Attached Figure Description

[0030] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0031] Figure 1 This is a schematic diagram of the overall design of this utility model. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0033] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," and "back," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] Furthermore, in the description of this utility model, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model in light of the specific circumstances.

[0035] The following will refer to the appendix. Figure 1 The present invention will be described in detail with reference to the embodiments.

[0036] Overall, this utility model proposes an uninterruptible power supply switching circuit, including a photovoltaic system and a dual power transfer switch; the first input terminal of the dual power transfer switch is connected to the output terminal of the photovoltaic power supply system, the second input terminal is connected to the external power supply terminal, and the output terminal is connected to the input terminal of the uninterruptible power supply.

[0037] The communication terminal of the dual power supply transfer switch is connected to the communication terminal of the uninterruptible power supply (UPS) for reading the output voltage of the UPS.

[0038] The dual power supply transfer switch is configured such that when the output voltage of the uninterruptible power supply (UPS) is less than a preset voltage value, it connects the external power supply to the UPS and disconnects the output of the photovoltaic power supply system from the UPS. Conversely, when the output voltage of the UPS is greater than a preset voltage value, it connects the output of the photovoltaic power supply system to the UPS and disconnects the external power supply from the UPS.

[0039] With the automatic switching function of the dual power transfer switch, the circuit can dynamically adjust the power source according to the real-time usage of the uninterruptible power supply (UPS), ensuring a stable power supply and normal operation of the load equipment. This dynamic adjustment capability greatly improves the reliability and stability of the power supply.

[0040] It should be noted that in this embodiment, the input terminal of the uninterruptible power supply refers to the charging port of the UPS. The output terminal of the photovoltaic system or the external power supply terminal supplies power to the UPS battery through the dual power transfer switch and the input port. At the same time, the dual power transfer switch monitors the battery voltage through the input terminal of the uninterruptible power supply.

[0041] Furthermore, this circuit fully utilizes the renewable energy advantages of photovoltaic systems, reducing reliance on the traditional power grid. Simultaneously, the uninterruptible power supply (UPS) acts as a buffer, alleviating the charging and discharging stress on the battery and extending its lifespan.

[0042] After the circuit starts, the dual power transfer switch first performs initialization settings, including setting the preset voltage value and detecting the connection status of the input and output terminals. Then, the switch begins real-time monitoring of the input voltage of the uninterruptible power supply (UPS). The dual power transfer switch compares the UPS input voltage with the preset voltage value. If the UPS input voltage is greater than the preset voltage value, it indicates that the photovoltaic power supply is sufficient and of good quality, the photovoltaic power supply system can provide stable power to the UPS, and the UPS's discharge and charging processes are balanced. In this case, the switch connects the output terminal of the photovoltaic power supply system to the UPS, while simultaneously disconnecting the external power supply from the UPS. Conversely, if the UPS input voltage is less than the preset voltage value, it indicates that the photovoltaic power supply is insufficient or of poor quality, the UPS's discharge exceeds its charging, and the remaining battery capacity within the UPS is insufficient. In this case, the switch connects the external power supply to the UPS to ensure continuous power supply. The batteries in an uninterruptible power supply (UPS) can extend their lifespan by using charging and discharging processes, thus preventing them from being in a float charging state for extended periods.

[0043] It should be noted that the photovoltaic power supply system includes photovoltaic modules and a controller; the controller includes at least an input terminal and an output terminal; the output terminal of the photovoltaic module is connected to the input terminal of the controller; the output terminal of the controller is connected to the first input terminal of the dual power transfer switch. The controller is an MPPT controller that supports battery-free mode.

[0044] When the photovoltaic power supply system is started, the photovoltaic modules begin to receive solar energy and convert it into electrical energy. The input terminal of the controller receives electrical energy from the photovoltaic modules, and the dual power transfer switch is also initialized, ready to receive electrical energy from the controller or an external power supply terminal and provide it to the uninterruptible power supply.

[0045] As an MPPT controller supporting battery-free mode, the controller dynamically adjusts the operating point of the photovoltaic modules to ensure that they always operate at maximum power output. The controller then transmits the MPPT-optimized electrical energy to the first input of the dual power transfer switch through its output.

[0046] Through optimized control by the MPPT controller, the photovoltaic modules always operate at maximum power output, improving power supply efficiency.

[0047] In battery-free mode, the MPPT controller achieves stable system operation through the following methods:

[0048] Photovoltaic priority power supply and dynamic switching: When the photovoltaic modules output sufficient power (e.g., under good sunlight conditions), the MPPT controller tracks the maximum power point of the photovoltaic modules in real time and directly delivers the optimized power to the dual power transfer switch, prioritizing power supply to the uninterruptible power supply (UPS) and the load. In this case, the UPS, acting as a power buffer, only needs to smooth out instantaneous fluctuations in photovoltaic output and does not need to perform energy storage functions, thus reducing reliance on batteries.

[0049] External power grid / UPS collaborative buffering mechanism: When the photovoltaic output power is insufficient (e.g., at night, in cloudy or rainy weather) or the voltage is lower than a preset threshold, the MPPT controller sends a switching signal to the dual power transfer switch, immediately cutting off the photovoltaic power supply path and connecting to the external power grid. During this process, the UPS provides millisecond-level transition power at the moment of switching through its internal capacitors or flywheel energy storage components, ensuring uninterrupted power supply to the load equipment. The external power grid, as the main power source, provides stable power to the load through the UPS's rectification-inversion stage.

[0050] Control Logic and Stability Guarantee: The MPPT controller has a built-in voltage / frequency detection module that monitors the photovoltaic output and grid status in real time. When the photovoltaic voltage recovers to above the preset threshold, the controller automatically triggers reverse switching, prioritizing photovoltaic power supply and cutting off the external grid connection.

[0051] In both modes, the UPS acts as a "voltage regulator" and "instantaneous buffer," using its inverter to output a pure sine wave to suppress voltage surges, drops, and other interference, ensuring power quality at the load end.

[0052] It should be noted that the controller is also used to monitor the output voltage of the photovoltaic module through the input terminal. When the output voltage is greater than the first preset voltage (such as 544V), the normally closed contact DC1 of the controller is opened.

[0053] In another embodiment, if the controller also includes a battery, then the controller also includes a battery connection terminal. The controller connects to the battery through the battery connection terminal to charge the battery through the photovoltaic module and discharge the terminal device through the battery. In this embodiment, the controller monitors the working voltage of the battery through the battery connection terminal. When the working voltage of the battery is less than a second preset voltage (e.g., 360V), the normally open contact DC2 of the controller closes.

[0054] In this embodiment, the photovoltaic power supply system further includes an overvoltage protection circuit; the overvoltage protection circuit includes a first fuse FU1, a second fuse FU2, a first button SB1, a second button SB2, and a contactor KM1;

[0055] The controller is also equipped with normally closed contacts and normally open contacts; the controller's output terminals include at least a first output terminal and a second output terminal; the first output terminal of the controller is connected to one end of the second fuse FU2, the other end of the second fuse FU2 is connected to one end of the normally closed contact DC1 of the controller, the other end of the normally closed contact DC1 of the controller is connected to one end of the first button SB1, the other end of the first button SB1 is connected to one end of the second button SB2, one end of the normally open auxiliary contact of contactor KM1, and one end of the normally open contact DC2 of the controller; the other end of the second button SB2, the other end of the normally open auxiliary contact of contactor KM1, and the other end of the normally open contact DC2 of the controller are respectively connected to one end of the drive coil of contactor KM1, the other end of the drive coil of contactor KM1 is connected to one end of the first fuse FU1, the other end of the first fuse FU1 is connected to the second output terminal of the controller; the controller's output terminal is connected to one end of the normally open main contact of contactor KM1, and the other end of the normally open main contact of contactor KM1 is connected to the first input terminal of the dual power supply transfer switch.

[0056] When the system voltage exceeds the preset safety range, the overvoltage protection circuit is activated. The first output terminal of the controller is connected to one end of the second fuse FU2, which acts as a short-circuit protection element to prevent excessive current during a short circuit. The other end of the second fuse FU2 is connected to one end of the normally closed contact DC1 of the controller. This contact closes when the voltage is normal, allowing current to flow. The other end of the normally closed auxiliary contact is connected to one end of the first button SB1, which is typically used as a test button to test the function of the overvoltage protection circuit. The other end of the first button SB1 is connected to one end of the second button SB2 (reset button), one end of the normally open auxiliary contact of contactor KM1, and one end of the normally open contact DC2 of the controller. After the normally closed auxiliary contact opens due to excessive voltage, the reset button must be pressed to close the circuit again. The other ends of the second button SB2, the normally open auxiliary contact of contactor KM1, and the normally open contact DC2 of the controller are each connected to one end of the drive coil of contactor KM1. After the drive coil is energized, contactor KM1 actuates, its normally open main contacts close, allowing current to flow to the dual power supply transfer switch. The other end of the drive coil of contactor KM1 is connected to one end of the first fuse FU1, forming a circuit. The first fuse FU1 serves as a protective element for the main circuit, preventing excessive current. The second output terminal of the controller is connected to the other end of the first fuse FU1, but in actual normal operation, the current mainly flows to the dual power supply transfer switch through the first output terminal of the controller and the overvoltage protection circuit. The introduction of the overvoltage protection circuit effectively prevents equipment damage and fire risks caused by excessive voltage.

[0057] It should be further explained that the photovoltaic power supply system also includes a circuit breaker QF; the output of the controller is connected to one end of the circuit breaker QF, and the other end of the circuit breaker QF is connected to the first input of the dual power transfer switch. The circuit breaker QF can quickly cut off the power supply in the event of overload, short circuit or other faults in the circuit, preventing excessive current from damaging the circuit and equipment.

[0058] Furthermore, the preset voltage range of the dual power supply transfer switch is DC380-DC500V. In practice, when the output voltage of the uninterruptible power supply (UPS) is ≥ the preset value, the dual power supply transfer device automatically operates, the mains power supply stops, and the photovoltaic power generation supplies power to the central control UPS, ensuring stable power supply from the UPS to monitoring equipment and nighttime road lighting facilities, achieving energy conservation, emission reduction, and green electricity use. In rainy or snowy weather or at night, when the output voltage of the UPS is ≤ the preset value, the dual power supply transfer device activates, switching to mains power supply, and the photovoltaic power generation stops, ensuring stable power supply from the UPS to monitoring equipment and nighttime road lighting facilities. More specifically, when the UPS voltage is below 380V, it is powered by mains power. In a preferred embodiment, this example adds a power switching method: the voltage detection module of the dual power supply transfer switch is also used to obtain the real-time output voltage of the controller (i.e., the output voltage of the photovoltaic module after modulation by the controller). When this voltage is above 500V, the mains power is cut off, and power is supplied by solar photovoltaic power.

[0059] In addition, as a possible real-time method, the dual power supply transfer switch may include a voltage detection module, a voltage comparator, and an automatic transfer switch;

[0060] The voltage detection module detects the output voltage of the uninterruptible power supply (UPS), and the voltage comparator compares the UPS output voltage with a preset voltage value. When the UPS output voltage is lower than the preset voltage value, a first signal is output, and the automatic transfer switch responds to the first signal, connecting the external power supply to the UPS and disconnecting the photovoltaic power supply system's output from the UPS. When the UPS output voltage is higher than the preset voltage value, a second signal is output, connecting the photovoltaic power supply system's output to the UPS and disconnecting the external power supply. In this embodiment, the external power supply is AC mains power.

[0061] In this embodiment, as another possible implementation, the dual-power transfer switch uses a programmable logic controller (PLC) as its control core. Its 485 interface is connected to the communication terminal of the uninterruptible power supply (UPS), and the output voltage of the UPS is read in real time using the Modbus protocol. On the other hand, the digital output terminal of the PLC is connected to one end of the coil of the first relay, and the other end of the coil of the first relay is connected to the common terminal of the PLC. One end of the normally open contact of the first relay serves as the first input terminal, connected to the output terminal of the photovoltaic power supply system, and one end of the normally closed contact of the first relay serves as the second input terminal, connected to the external power supply. The other ends of the normally open contacts of the first and second relays serve as the output terminals of the dual-power transfer switch, connected to the input terminals of the UPS. The PLC reads the output voltage of the UPS. If the output voltage of the UPS is less than a preset voltage value, the connection between the external power supply and the UPS is established, and the connection between the output terminal of the photovoltaic power supply system and the UPS is disconnected. If the output voltage of the UPS is greater than the preset voltage value, the connection between the output terminal of the photovoltaic power supply system and the UPS is established, and the connection between the external power supply and the UPS is disconnected. It should be noted that in this embodiment, the dual power supply transfer switch can be used not only for two-wire systems but also for three-wire systems, and no limitation is made here.

[0062] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An uninterruptible power supply switching circuit, characterized in that: This includes photovoltaic systems and dual power transfer switches; The first input terminal of the dual power supply transfer switch is connected to the output terminal of the photovoltaic power supply system, the second input terminal is connected to the external power supply terminal, and the output terminal is connected to the input terminal of the uninterruptible power supply. The communication terminal of the dual power supply transfer switch is connected to the communication terminal of the uninterruptible power supply (UPS) for reading the output voltage of the UPS. The dual power supply transfer switch is configured such that when the output voltage of the uninterruptible power supply is less than a preset voltage value, the connection between the external power supply and the uninterruptible power supply is made, and the connection between the output of the photovoltaic power supply system and the uninterruptible power supply is made, and when the output voltage of the uninterruptible power supply is greater than a preset voltage value, the connection between the output of the photovoltaic power supply system and the uninterruptible power supply is made, and the connection between the external power supply and the uninterruptible power supply is made. The dual power supply transfer switch includes a voltage detection module, a voltage comparator, and an automatic transfer switch; The voltage detection module is used to detect the output voltage of the uninterruptible power supply; The voltage comparator is used to compare the output voltage of the uninterruptible power supply with a preset voltage value; When the output voltage of the uninterruptible power supply is less than the preset voltage value, the first signal is output. The automatic transfer switch is used to respond to the first signal to connect the external power supply terminal and the uninterruptible power supply, and to disconnect the output terminal of the photovoltaic power supply system from the uninterruptible power supply. The voltage comparator is also used to output a second signal when the output voltage of the uninterruptible power supply is greater than a preset voltage value, thereby connecting the output of the photovoltaic power supply system to the uninterruptible power supply and disconnecting the external power supply from the uninterruptible power supply.

2. The uninterruptible power supply switching circuit according to claim 1, characterized in that: The photovoltaic power supply system includes photovoltaic modules and a controller; The controller includes at least an input terminal and an output terminal; The output terminal of the photovoltaic module is connected to the input terminal of the controller; The output of the controller is connected to the first input of the dual power transfer switch.

3. The uninterruptible power supply switching circuit according to claim 2, characterized in that: The controller is an MPPT controller that supports battery-free mode.

4. The uninterruptible power supply switching circuit according to claim 2, characterized in that: The photovoltaic power supply system also includes an overvoltage protection circuit; The overvoltage protection circuit includes a first fuse, a second fuse, a first button, a second button, and a contactor; The controller is also provided with normally closed contacts and normally open contacts; The controller's output terminals include at least a first output terminal and a second output terminal; The first output terminal of the controller is connected to one end of the second fuse, the other end of the second fuse is connected to one end of the normally closed contact of the controller, the other end of the normally closed contact of the controller is connected to one end of the first button, the other end of the first button is connected to one end of the second button, one end of the normally open auxiliary contact of the contactor, and one end of the normally open contact of the controller; the other end of the second button, the other end of the normally open auxiliary contact of the contactor, and the other end of the normally open contact of the controller are respectively connected to one end of the drive coil of the contactor, the other end of the drive coil of the contactor is connected to one end of the first fuse, and the other end of the first fuse is connected to the second output terminal of the controller. The first input terminal of the dual power supply transfer switch includes at least a first interface and a second interface; The first output terminal of the controller is connected to one end of the first normally open main contact of the contactor, and the other end of the first normally open main contact of the contactor is connected to the first interface of the first input terminal of the dual power supply transfer switch. The second output terminal of the controller is connected to one end of the second normally open main contact of the contactor, and the other end of the second normally open main contact of the contactor is connected to the second interface of the first input terminal of the dual power supply transfer switch.

5. The uninterruptible power supply switching circuit according to claim 2, characterized in that: The photovoltaic power supply system also includes a circuit breaker; The output of the controller is connected to one end of the circuit breaker, and the other end of the circuit breaker is connected to the first input of the dual power transfer switch.

6. The uninterruptible power supply switching circuit according to claim 1, characterized in that: The preset voltage value ranges from DC380V to DC500V.

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