Power conversion circuit and UPS system

Abstract

The invention relates to the technical field of power electronic conversion, and discloses a power conversion circuit and a UPS (Uninterrupted Power Supply) system, which realize an AC / DC (Alternating Current / Direct Current) rectification function in a mains supply mode and a DC / DC boosting function in a battery mode on a single set of hardware through innovative circuit design and device multiplexing on the premise of not obviously increasing hardware cost, and further realize a power conversion function in a battery mode. The system structure is simplified, the cost is reduced, and the power density is improved. According to the design, the multifunctionality of the existing device is fully utilized, and the problems of hardware redundancy and cost increase are avoided. Meanwhile, as the number of devices and the circuit complexity are reduced, the reliability of the system is improved, and the maintenance difficulty is reduced. Besides, due to the improvement of the power density, the whole power conversion circuit can support higher power output under the same size, or more compact design can be realized under the same power requirement, and powerful support is provided for integration and miniaturization of medium-power UPS power supply equipment.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion technology, and in particular to a power conversion circuit and a UPS system. Background Technology

[0002] In UPS systems, a front-end AC / DC rectifier circuit is typically required to convert the AC mains power into a stable DC bus voltage and charge the downstream inverter and battery. Simultaneously, when the mains power is abnormal, a DC / DC boost circuit is needed to boost the low-voltage DC power from the battery to the bus voltage to maintain system power supply. Single-phase Vienna rectifiers, due to their high power factor, low harmonics, and low switching transistor voltage stress, have become one of the mainstream topologies for the front-end AC / DC converters in small and medium power UPS systems.

[0003] However, traditional UPS designs typically use separate circuits for AC / DC rectification and battery DC / DC boost. For example, the battery boost circuit often employs push-pull, full-bridge, dual-boost, or three-level buck / boost circuits. This separate design leads to an increase in the number of power switches, inductors, drive circuits, and other components used in the system, increasing system cost, size, and complexity, and hindering the achievement of high power density and miniaturization in UPS products.

[0004] Therefore, how to design an efficient and compact circuit that can reuse the main power devices and realize AC / DC rectification in mains power mode and DC / DC boost in battery mode on a single set of hardware has become a technical problem that urgently needs to be solved in this field.

[0005] The above information is provided as background information only to aid in understanding the present invention, and does not constitute an assertion or admission that any of the above content can be used as prior art relative to the present invention. Summary of the Invention

[0006] This invention provides a power conversion circuit and a UPS system to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a power conversion circuit, including an AC / DC conversion module, a DC / DC conversion module, and a switching module; wherein...

[0009] The switching module is connected to both the AC / DC conversion module and the DC / DC conversion module, and is used to switch between AC power mode and battery mode.

[0010] The AC / DC conversion module is connected to the mains power line L and is used to convert the AC power input from the mains power line L into DC power in the mains power mode to generate positive and negative DC bus voltages.

[0011] The neutral line N is connected in the middle of the positive and negative DC bus voltages;

[0012] The DC / DC conversion module is connected to the first battery BAT1 and the second battery BAT2, and is used in the battery mode to reuse the devices of the AC / DC conversion module to boost the positive and negative DC bus voltages generated by the first battery BAT1 and the second battery BAT2.

[0013] Furthermore, in the power conversion circuit, the AC / DC conversion module includes a first switch Q1, a second switch Q2, a first diode D1, a second diode D2, a PFC inductor L1, a positive bus capacitor C1, and a negative bus capacitor C2;

[0014] The source of the first switching transistor Q1 is connected to the source of the second switching transistor Q2, and the drain of the first switching transistor Q1 is connected in series with the PFC inductor L1 and then connected to the mains power line L via the switching module.

[0015] The drain of the second switching transistor Q2 is connected to the neutral line N;

[0016] The anode of the first diode D1 is connected to the drain of the first switching transistor Q1, and the cathode of the first diode D1 is connected to the neutral line N after being connected in series with the positive bus capacitor C1.

[0017] The cathode of the second diode D2 is connected to the drain of the first switching transistor Q1, and the anode of the second diode D2 is connected to the neutral line N after being connected in series with the negative bus capacitor C2.

[0018] Furthermore, in the power conversion circuit, the DC / DC conversion module includes a third switch Q3 and a fourth switch Q4;

[0019] The drain of the third switch Q3 is connected to the positive terminal of the first battery BAT1; the source of the third switch Q3 is connected to the midpoint between the drain of the second switch Q2 and the neutral line N.

[0020] The negative terminal of the first battery BAT1 is connected to the switching module;

[0021] The source of the fourth switch Q4 is connected to the negative terminal of the second battery BAT2; the drain of the fourth switch Q4 is connected to the midpoint between the drain of the second switch Q2 and the neutral line N.

[0022] The positive terminal of the second battery BAT2 is connected to the switching module.

[0023] Furthermore, in the power conversion circuit, the switching module includes a first switch K1, a second switch K2, and a third switch K3;

[0024] The first switch K1 is connected in series between the PFC inductor L1 and the mains live wire L;

[0025] The second switch K2 is connected in series between the negative terminal of the first battery BAT1 and the PFC inductor L1;

[0026] The third switch K3 is connected in series between the positive terminal of the second battery BAT2 and the PFC inductor L1.

[0027] Furthermore, the power conversion circuit also includes a control module;

[0028] The control module is connected to the first switch K1, the second switch K2 and the third switch K3, and is used to control the on / off state of each switch.

[0029] Furthermore, in the power conversion circuit, during the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is turned on.

[0030] During the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is turned on.

[0031] Furthermore, in the power conversion circuit, the positive half-cycle of the mains power mode includes a first stage and a second stage;

[0032] In the first stage of the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is turned on. The current path is: mains live wire L - PFC inductor L1 - first switch Q1 - body diode of second switch Q2 - neutral wire N.

[0033] In the second phase of the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is opened. The current path is: mains live wire L-PFC inductor L1-first diode D1-positive bus capacitor C1-neutral line N.

[0034] The negative half-cycle of the mains power mode includes a first phase and a second phase;

[0035] In the first phase of the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is turned on. The current path is: neutral line N - second switch Q2 - body diode of the first switch Q1 - PFC inductor L1 - mains power line L.

[0036] In the second phase of the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is opened. The current path is: neutral line N - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - mains live wire L.

[0037] Furthermore, in the power conversion circuit, during the positive half-cycle of the battery mode, the first switch K1 is controlled to open, the second switch K2 and the third switch K3 are controlled to close, and the first switch Q1 and the fourth switch Q4 are controlled to work together.

[0038] During the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the second switch Q2 and the third switch Q3 are controlled to work together.

[0039] Furthermore, in the power conversion circuit, the positive half-cycle of the battery mode includes a first stage and a second stage;

[0040] In the first phase of the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the first switch Q1 and the fourth switch Q4 are turned on. The current path is: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - body diode of the first switch Q1 - fourth switch Q4 - negative terminal of the second battery BAT2.

[0041] In the second phase of the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the fourth switch Q4 is turned on. The current path is: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - first diode D1 - positive bus capacitor C1 - fourth switch Q4 - negative terminal of the second battery BAT2.

[0042] The negative half-cycle of the battery mode includes a first phase and a second phase;

[0043] In the first stage of the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the second switch Q2 and the third switch Q3 are turned on. The current path is: positive terminal of the first battery BAT1 - third switch Q3 - second switch Q2 - body diode of the first switch Q1 - PFC inductor L1 - second switch K2 - negative terminal of the first battery BAT1.

[0044] In the second phase of the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the third switch Q3 is turned on. The current path is: positive terminal of the first battery BAT1 - third switch Q3 - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - second switch K2 - negative terminal of the first battery BAT1.

[0045] In a second aspect, the present invention provides a UPS system including the power conversion circuit as described in the first aspect above.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This invention provides a power conversion circuit and UPS system that, through innovative circuit design, achieves efficient multiplexing of AC / DC rectification and DC / DC boost functions within the UPS system. Specifically, by flexibly switching between mains mode and battery mode via a switching module, the AC / DC conversion module can efficiently convert AC power to a stable DC bus voltage when the mains power is normal. When the mains power is abnormal, the DC / DC conversion module reuses components from the AC / DC conversion module to boost the low-voltage DC power from the battery to the required bus voltage, maintaining system power supply. This multiplexing design significantly reduces the number of components, thereby substantially reducing the system's hardware cost, size, and complexity. Simultaneously, by reducing the number of components and optimizing the circuit structure, system reliability is improved, and maintenance difficulty is reduced. Furthermore, this design increases power density, enabling the UPS system to achieve higher power output in a smaller volume, or a more compact design for the same power requirements. This provides strong support for high power density and miniaturization of UPS products, promoting the development of UPS technology towards high efficiency, compactness, and economy.

[0048] The present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is one of the circuit principle diagrams of a power conversion circuit provided in Embodiment 1 of the present invention;

[0051] Figure 2 This is a schematic diagram of the current path in the first stage of the positive half-cycle of the mains power mode provided in Embodiment 1 of the present invention.

[0052] Figure 3 This is a schematic diagram of the current path in the second stage of the positive half-cycle of the mains power mode provided in Embodiment 1 of the present invention.

[0053] Figure 4 This is a schematic diagram of the current path in the first stage of the negative half-cycle of the mains power mode provided in Embodiment 1 of the present invention.

[0054] Figure 5 This is a schematic diagram of the current path in the second stage of the negative half-cycle of the mains power mode provided in Embodiment 1 of the present invention.

[0055] Figure 6 This is a schematic diagram of the current path in the first stage of the positive half-cycle of the battery mode, provided in Embodiment 1 of the present invention.

[0056] Figure 7 This is a schematic diagram of the current path in the second stage of the positive half-cycle of the battery mode, provided in Embodiment 1 of the present invention.

[0057] Figure 8 This is a schematic diagram of the current path in the first stage of the negative half-cycle of battery mode provided in Embodiment 1 of the present invention.

[0058] Figure 9 This is a schematic diagram of the current path in the second stage of the negative half-cycle of battery mode, provided in Embodiment 1 of the present invention. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1

[0061] This invention provides a power conversion circuit, including an AC / DC conversion module, a DC / DC conversion module, and a switching module; wherein,

[0062] The switching module plays a crucial role in the entire circuit. It is connected to both the AC / DC conversion module and the DC / DC conversion module. Its core function is to switch between two different operating modes, AC power mode and battery mode, according to actual needs.

[0063] The AC / DC conversion module is connected to the mains live wire L, and the neutral wire N is connected in the middle of the positive and negative DC bus voltages. Under normal mains power mode, the module performs its core conversion function, converting the AC power input from the mains live wire L into DC power through circuit processing and conversion, thereby generating positive and negative DC bus voltages that meet the system operation requirements, providing stable DC power support for the normal operation of subsequent circuits.

[0064] The DC / DC conversion module is connected to the first battery BAT1 and the second battery BAT2. When the system is in battery mode, this module exhibits a unique reuse advantage. It can cleverly reuse some components in the AC / DC conversion module, making full use of the functional characteristics of these existing components to boost the positive and negative DC bus voltages generated by the first battery BAT1 and the second battery BAT2, so as to meet the specific voltage requirements of the system under different operating scenarios.

[0065] This invention, through a highly innovative circuit design concept, successfully achieves efficient multiplexing of AC / DC rectification and DC / DC boost functions in an uninterruptible power supply (UPS) system. Specifically, by leveraging the flexible, rapid, and stable switching capability of the switching module between mains mode and battery mode, the AC / DC conversion module can efficiently convert AC power into stable and reliable positive and negative DC bus voltages when the mains power is on normal supply, providing a solid power foundation for the stable operation of the entire UPS system. When mains power anomalies occur, such as power outages or excessive voltage fluctuations, the DC / DC conversion module quickly comes into play. By reusing relevant components in the AC / DC conversion module, it boosts the low-voltage DC power output from the batteries (i.e., the first battery BAT1 and the second battery BAT2) to the bus voltage level required for normal system operation. This ensures that the UPS system can continue to supply power to the load equipment continuously and stably during mains power anomalies, guaranteeing uninterrupted normal operation of the equipment.

[0066] This innovative reuse design offers several significant advantages. First, in terms of hardware cost, the clever reuse of components greatly reduces the number of components required, effectively lowering the system's hardware procurement cost. Second, regarding system size, the reduced number of components allows for a more compact layout of the entire power conversion circuit, significantly reducing the physical space occupied and facilitating the miniaturization of the UPS system. Furthermore, in terms of system complexity, the reduction of unnecessary components and connections results in a simpler and clearer circuit structure, lowering the system's complexity. This not only helps improve the overall reliability of the system but also greatly simplifies maintenance, reducing maintenance difficulty and costs.

[0067] Furthermore, this innovative design also has a positive impact on power density. By optimizing circuit design and reusing components, UPS systems can achieve higher power output within the same volume, meeting the needs of applications with high power requirements; or, while maintaining the same power output requirements, a more compact system design can be achieved, further reducing the system size. This characteristic provides strong technical support for the development of UPS products towards high power density and miniaturization, powerfully promoting the continuous advancement of UPS technology towards efficiency, compactness, and economy. While improving product performance, it also enhances the product's competitiveness in the market, injecting new vitality into the innovative development of the UPS industry.

[0068] Please refer to Figure 1 In one embodiment of this invention, the AC / DC conversion module includes a first switch Q1, a second switch Q2, a first diode D1, a second diode D2, a PFC inductor L1, a positive bus capacitor C1, and a negative bus capacitor C2. These components cooperate with each other through a carefully designed connection method to jointly realize the AC / DC conversion function.

[0069] The specific connection is as follows: The source of the first switching transistor Q1 is electrically connected to the source of the second switching transistor Q2, forming a common connection point. The drain of the first switching transistor Q1 is connected in series with the PFC inductor L1. This circuit branch, after being connected in series, is then connected to the AC power line L via a switching module, thereby establishing a connection channel with the AC power supply and providing an input signal for subsequent AC-to-DC conversion.

[0070] The drain of the second switching transistor Q2 is directly connected to the neutral line N. The neutral line N serves as the reference potential point of the AC power supply, providing a stable potential reference for the entire circuit.

[0071] The anode of the first diode D1 is connected to the drain of the first switching transistor Q1, and its cathode is connected in series with the positive bus capacitor C1. The series circuit is then connected to the neutral line N. During circuit operation, the first diode D1 serves as a rectifier and protector, ensuring that the current flows only in a specific direction. At the same time, the positive bus capacitor C1 stores and stabilizes the DC voltage on the positive bus, providing a stable positive DC power supply for subsequent circuits.

[0072] The cathode of the second diode D2 is also connected to the drain of the first switching transistor Q1, and its anode is connected in series with the negative bus capacitor C2. The series circuit is also connected to the neutral line N. The second diode D2 has a similar function to the first diode D1, which is to perform a specific current guiding function in the circuit, while the negative bus capacitor C2 is used to store and stabilize the DC voltage on the negative bus, providing a stable negative DC power supply for the subsequent circuit.

[0073] Through the precise connection and coordinated operation of the above components, the AC / DC conversion module can efficiently convert the AC power input from the mains live wire L into a stable positive and negative DC bus voltage in mains power mode, providing reliable DC power support for the entire power conversion circuit and the load equipment connected thereafter, and ensuring the stable operation of the system when the mains power is normally supplied.

[0074] Please refer to this again. Figure 1 In one embodiment of this invention, the DC / DC conversion module includes a third switch Q3 and a fourth switch Q4. These two switches are electrically connected to the first battery BAT1, the second battery BAT2, and other parts of the circuit through a carefully planned connection method, and together complete the DC / DC conversion function.

[0075] The specific connection is as follows: The drain of the third switch Q3 is closely connected to the positive terminal of the first battery BAT1, establishing a current path from the positive terminal of the battery to the switch. The source of the third switch Q3 is connected to the midpoint formed by the drain of the second switch Q2 and the neutral line N. This connection point plays an important role in potential reference and current distribution in the entire circuit.

[0076] The negative terminal of the first battery BAT1 is connected to the switching module. Through the function of the switching module, the connection status between the negative terminal of the battery and other parts of the circuit can be flexibly controlled according to the system's working mode (mains power mode or battery mode), thereby realizing the function switching between different modes.

[0077] The source of the fourth switch Q4 is connected to the negative terminal of the second battery BAT2, providing a path for the negative current output of the second battery. The drain of the fourth switch Q4 is also connected to the midpoint between the drain of the second switch Q2 and the neutral line N, and is connected to the same critical node as the source of the third switch Q3. This allows the two switches to cooperate with each other during circuit operation to adjust and switch the battery voltage.

[0078] The positive terminal of the second battery BAT2 is also connected to the switching module, echoing the connection method of the negative terminal of the first battery BAT1. Through the unified control of the switching module, it is ensured that in battery mode, the two batteries can provide the DC / DC conversion module with the appropriate input voltage according to the design requirements, and realize the voltage boosting and other functions in subsequent processing to meet the DC voltage requirements of the system in different working scenarios.

[0079] Through the precise component connection method described above, the DC / DC conversion module can fully utilize its function in battery mode. When the system switches to battery mode, the third switch Q3 and the fourth switch Q4 are turned on and off under the action of control signals. Combined with the voltage characteristics of the first battery BAT1 and the second battery BAT2, and the multiplexing relationship with some components in the AC / DC conversion module, the battery output voltage is boosted, converting the low-voltage DC power from the battery into a bus voltage that meets the system requirements. This ensures that the UPS system can continuously and stably power the load equipment when the mains power is abnormal, ensuring the reliable operation of the system.

[0080] Please refer to this again. Figure 1 In one embodiment of this invention, the switching module includes a first switch K1, a second switch K2, and a third switch K3. These three switches are connected in a specific series manner and cooperate with other key components in the circuit to ensure the stable operation of the system under different power input conditions.

[0081] The specific connection is as follows: The first switch K1 is connected in series in the circuit path between the PFC inductor L1 and the AC power live wire L. During normal operation in AC power mode, the first switch K1 is in the ON state, establishing an electrical connection between the AC power live wire L and the PFC inductor L1, allowing AC power to be smoothly input into the AC / DC conversion module, providing the necessary power input for the subsequent AC-to-DC conversion process. When the system needs to switch to battery mode, the first switch K1 is controlled to the OFF state, cutting off the connection between the AC power and the subsequent circuits, preventing AC power from interfering with the circuit operation in battery mode.

[0082] The second switch K2 is connected in series in the circuit branch between the negative terminal of the first battery BAT1 and the PFC inductor L1. In battery mode, the second switch K2 is turned on, connecting the negative terminal of the first battery BAT1 to the circuit containing the PFC inductor L1, allowing the first battery BAT1 to act as a power source, providing input current to the DC / DC converter module and participating in subsequent voltage conversion and system power supply processes. In AC power mode, the second switch K2 is turned off, preventing the first battery BAT1 from affecting the AC power input circuit and ensuring independent and stable operation of the circuit in AC power mode.

[0083] The third switch K3 is also connected in series in the circuit between the positive terminal of the second battery BAT2 and the PFC inductor L1. In battery mode, the third switch K3 is on, connecting the positive terminal of the second battery BAT2 to the circuit containing the PFC inductor L1. Together with the first battery BAT1, they provide the necessary input power to the DC / DC converter module to meet the system's power requirements in battery mode. When the system is in AC power mode, the third switch K3 is off, isolating the second battery BAT2 from the AC power input circuit, ensuring that the circuit operates normally in AC power mode without being affected by the battery.

[0084] Through precise on / off control of the three switches, the switching module can flexibly adjust the circuit connection status according to the actual operating mode of the system, achieving seamless switching between mains power and battery power. When the mains power is normal, it ensures that the mains power can efficiently supply power to the system through the AC / DC conversion module; while when the mains power is abnormal, it quickly switches to battery mode, using the first battery BAT1 and the second battery BAT2 to provide continuous and stable power support to the system through the DC / DC conversion module. This ensures that the entire UPS system can operate reliably and stably under different operating conditions, providing uninterrupted power protection for the load equipment.

[0085] In one embodiment of this invention, the circuit further includes a control module;

[0086] The control module is connected to the first switch K1, the second switch K2 and the third switch K3, and is used to control the on / off state of each switch.

[0087] In one embodiment of this example, during the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is turned on.

[0088] During the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is turned on.

[0089] Please refer to Figure 2-3 In one embodiment of this example, the positive half-cycle of the mains power mode includes a first stage and a second stage.

[0090] In the first phase of the positive half-cycle of the mains power mode, the switches in the circuit are controlled as follows: the first switch K1 is closed, which establishes an electrical connection between the mains live wire L and the PFC inductor L1, providing a path for the input of AC mains power; the second switch K2 and the third switch K3 are opened, effectively isolating the first battery BAT1 and the second battery BAT2 from the mains input circuit, preventing the batteries from interfering with the mains input, and ensuring the independent and stable operation of the circuit in mains power mode. Simultaneously, the first switch Q1 is turned on.

[0091] At this time, the current path is: mains live wire L - PFC inductor L1 - first switching transistor Q1 - body diode of second switching transistor Q2 - neutral wire N; as Figure 2 As shown, the alternating current of the mains power during the positive half-cycle forms a loop through this path. When the current flows through the PFC inductor L1, the inductor generates a magnetic field and stores energy. This process not only achieves the initial conduction of the current, but the PFC inductor L1 also plays a certain role in smoothing and shaping the current, which helps to reduce current harmonics, improve the power factor, and enable the circuit to utilize mains power energy more efficiently.

[0092] In the second phase of the positive half-cycle of the mains power mode, the switch control state remains unchanged with the first switch K1 closed, the second switch K2 and the third switch K3 open, but the first switch Q1 is turned off.

[0093] At this point, the current path becomes: mains live wire L - PFC inductor L1 - first diode D1 - positive bus capacitor C1 - neutral wire N; (e.g., ...) Figure 3 As shown, with the first switch Q1 turned off, the energy stored in the PFC inductor L1 begins to be released, and the current charges the positive bus capacitor C1 through the first diode D1. A stable positive DC voltage is gradually established across the positive bus capacitor C1, providing a reliable positive DC power supply for subsequent circuits. This stage realizes the key step of converting AC mains power into positive DC power and storing it in the capacitor, providing a foundation for the stable operation of the system.

[0094] Please refer to Figure 4-5 In one embodiment of this example, the negative half-cycle of the mains power mode includes a first stage and a second stage.

[0095] In the first phase of the negative half-cycle of the mains power mode, the switch control is as follows: the first switch K1 remains closed, maintaining the connection between the mains live wire L and the PFC inductor L1 to ensure continuous AC mains power input; the second switch K2 and the third switch K3 remain open, continuing to isolate the battery from the mains input circuit. At this time, the second switch Q2 is turned on.

[0096] The current path is: neutral line N - second switch Q2 - body diode of first switch Q1 - PFC inductor L1 - mains wire L; For example Figure 4 As shown, the AC power in the negative half-cycle forms a loop through this path. When the current flows through the PFC inductor L1, it also stores energy and smooths the current, reducing harmonics and improving the power factor. Similar to the first stage of the positive half-cycle, this ensures the circuit's effective utilization of AC power energy in the negative half-cycle.

[0097] In the second phase of the negative half-cycle of the mains power mode, the switch control state maintains the first switch K1 closed, the second switch K2 and the third switch K3 open, and the second switch Q2 is turned off.

[0098] At this time, the current path is: neutral line N - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - mains live wire L; (e.g., ...) Figure 5 As shown, with the second switch Q2 off, the energy stored in the negative bus capacitor C2 begins to be released. Current flows through the second diode D2 and the PFC inductor L1 to form a circuit, further adjusting and releasing the energy in the PFC inductor L1. Simultaneously, this process also enables the negative bus capacitor C2 to maintain a stable negative DC voltage, providing a reliable negative DC power supply for subsequent circuits.

[0099] By dividing the positive and negative half-cycles of the mains power mode into two stages and employing the aforementioned precise switching control and current path design, the circuit in this embodiment offers several significant advantages. Regarding power factor correction, the PFC inductor L1 effectively smooths and shapes the current in different stages of the positive and negative half-cycles, reducing current harmonics and making the input current waveform closer to a sine wave, thereby significantly improving the power factor, reducing grid pollution, and increasing energy efficiency. In terms of voltage conversion, the charging process of the positive bus capacitor C1 and the negative bus capacitor C2 in different stages stably establishes the positive and negative DC bus voltages, providing reliable DC power support for subsequent circuits and ensuring stable system operation in mains power mode. Furthermore, this staged control method effectively avoids unnecessary charging and discharging operations of the battery in mains power mode, extending battery life and improving the overall reliability and economy of the system.

[0100] In one embodiment of this example, during the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the first switch Q1 and the fourth switch Q4 are controlled to work together.

[0101] During the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the second switch Q2 and the third switch Q3 are controlled to work together.

[0102] Please refer to Figure 6-7 In one embodiment of this example, the positive half-cycle of the battery mode includes a first stage and a second stage.

[0103] In the first phase of the positive half-cycle of the battery mode, the switches in the circuit are precisely controlled: the first switch K1 is open, effectively isolating the mains input circuit and preventing mains power from interfering with the circuit operation in battery mode, ensuring that the battery can independently and stably power the system; the second switch K2 and the third switch K3 are closed, establishing a connection channel between the second battery BAT2, the PFC inductor L1, and subsequent circuits. Simultaneously, the first switch Q1 and the fourth switch Q4 are turned on.

[0104] At this time, the current path is: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - body diode of the first switch Q1 - fourth switch Q4 - negative terminal of the second battery BAT2, as follows. Figure 6 As shown, the current output from the second battery BAT2 forms a loop through this path. When the current flows through the PFC inductor L1, the inductor begins to store energy. This process not only enables current conduction, but the PFC inductor L1 also plays a certain role in smoothing the current, helping to stabilize the current waveform, reducing the impact of current fluctuations on subsequent circuits, and laying the foundation for a stable voltage output.

[0105] In the second phase of the positive half-cycle of the battery mode, the switch control state remains unchanged with the first switch K1 open, the second switch K2 and the third switch K3 closed, and only the fourth switch Q4 is kept on while the first switch Q1 is open.

[0106] At this point, the current path becomes: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - first diode D1 - positive bus capacitor C1 - fourth switch Q4 - negative terminal of the second battery BAT2, as follows. Figure 7 As shown, with the first switch Q1 turned off, the energy stored in the PFC inductor L1 begins to be released, and the current charges the positive bus capacitor C1 through the first diode D1. A stable positive DC voltage is gradually established across the positive bus capacitor C1, providing a reliable positive DC power supply for subsequent circuits. This stage completes the crucial step of converting the electrical energy of the second battery BAT2 into positive DC and storing it in the capacitor, ensuring that the system can obtain a stable positive voltage supply in battery mode.

[0107] Please refer to Figure 8-9In one embodiment of this example, the negative half-cycle of the battery mode includes a first stage and a second stage.

[0108] During the first phase of the negative half-cycle of the battery mode, the switch control is as follows: the first switch K1 remains open, maintaining isolation between the mains power and the battery mode circuit; the second switch K2 and the third switch K3 remain closed, establishing the connection between the first battery BAT1, the PFC inductor L1, and subsequent circuits. At this time, the second switch Q2 and the third switch Q3 are turned on.

[0109] The current path is: positive terminal of first battery BAT1 - third switch Q3 - second switch Q2 - body diode of first switch Q1 - PFC inductor L1 - second switch K2 - negative terminal of first battery BAT1, as follows. Figure 8 As shown, the current output from the first battery BAT1 forms a loop through this path. When the current flows through the PFC inductor L1, it also stores energy and smooths the current, reducing current fluctuations and ensuring the stability of the current waveform, thus providing a guarantee for subsequent stable voltage output.

[0110] In the second phase of the negative half-cycle of the battery mode, the switch control state maintains the first switch K1 open, the second switch K2 and the third switch K3 closed, while keeping the third switch Q3 on and the second switch Q2 open.

[0111] At this time, the current path is: positive terminal of the first battery BAT1 - third switch Q3 - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - second switch K2 - negative terminal of the first battery BAT1, as follows. Figure 9 As shown, with the second switch Q2 off, the energy stored in the negative bus capacitor C2 begins to be released. Current flows through the second diode D2 and the PFC inductor L1 to form a circuit, further adjusting and releasing the energy in the PFC inductor L1. Simultaneously, this process also enables the negative bus capacitor C2 to maintain a stable negative DC voltage, providing a reliable negative DC power supply for subsequent circuits and ensuring a stable negative voltage supply for the system in battery mode.

[0112] By precisely controlling different stages of the positive and negative half-cycles in battery mode, the positive bus capacitor C1 and the negative bus capacitor C2 can be charged stably, thereby establishing stable positive and negative DC bus voltages, providing reliable DC power support for subsequent circuits, and ensuring stable operation of the system in battery mode.

[0113] The PFC inductor L1 can effectively store and release energy at different stages of the positive and negative half-cycles, smooth the current, reduce energy loss, improve battery energy utilization efficiency, extend battery life, and reduce system operating costs.

[0114] The first switch K1 is always off in battery mode, effectively isolating the mains input circuit and preventing mains power from interfering with the circuit operation in battery mode. It also prevents reverse power flow from the battery to the mains, thus protecting the safety of the circuit equipment.

[0115] This phased control method enables the system to flexibly switch between mains power mode and battery mode. When the mains power is abnormal, it can quickly switch to battery mode to provide uninterrupted power support for the load equipment, thereby improving the reliability and stability of the system.

[0116] It is understood that the switching transistors mentioned in this embodiment can be devices such as IGBTs, MOS, SiC, and GaN.

[0117] Although this invention uses terms such as power conversion circuit and control module frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

[0118] Example 2

[0119] Embodiment 2 of the present invention provides a UPS system, including the power conversion circuit provided in Embodiment 1 above.

[0120] It should be noted that by cleverly integrating the power conversion circuit in the above embodiment into the UPS system, the overall performance of the system is optimized and improved, laying a solid foundation for the stable and efficient operation of the UPS system in different application scenarios, and effectively meeting the stringent requirements of various users for uninterrupted power supply and power quality optimization.

[0121] Finally, it should be noted that although the above embodiments have been described in the description and drawings of this invention, this should not limit the scope of patent protection of this invention. Any technical solutions that are based on the essential concept of this invention, utilize the content described in the description and drawings of this invention to make equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this invention.

Claims

1. A power conversion circuit, characterized in that, It includes an AC / DC conversion module, a DC / DC conversion module, and a switching module; among which, The switching module is connected to both the AC / DC conversion module and the DC / DC conversion module, and is used to switch between AC power mode and battery mode. The AC / DC conversion module is connected to the mains power line L and is used to convert the AC power input from the mains power line L into DC power in the mains power mode to generate positive and negative DC bus voltages. The neutral line N is connected in the middle of the positive and negative DC bus voltages; The DC / DC conversion module is connected to the first battery BAT1 and the second battery BAT2, and is used in the battery mode to reuse the devices of the AC / DC conversion module to boost the positive and negative DC bus voltages generated by the first battery BAT1 and the second battery BAT2.

2. The power conversion circuit according to claim 1, characterized in that, The AC / DC conversion module includes a first switch Q1, a second switch Q2, a first diode D1, a second diode D2, a PFC inductor L1, a positive bus capacitor C1, and a negative bus capacitor C2. The source of the first switching transistor Q1 is connected to the source of the second switching transistor Q2, and the drain of the first switching transistor Q1 is connected in series with the PFC inductor L1 and then connected to the mains power line L via the switching module. The drain of the second switching transistor Q2 is connected to the neutral line N; The anode of the first diode D1 is connected to the drain of the first switching transistor Q1, and the cathode of the first diode D1 is connected to the neutral line N after being connected in series with the positive bus capacitor C1. The cathode of the second diode D2 is connected to the drain of the first switching transistor Q1, and the anode of the second diode D2 is connected to the neutral line N after being connected in series with the negative bus capacitor C2.

3. The power conversion circuit according to claim 2, characterized in that, The DC / DC conversion module includes a third switch Q3 and a fourth switch Q4; The drain of the third switch Q3 is connected to the positive terminal of the first battery BAT1; the source of the third switch Q3 is connected to the midpoint between the drain of the second switch Q2 and the neutral line N. The negative terminal of the first battery BAT1 is connected to the switching module; The source of the fourth switch Q4 is connected to the negative terminal of the second battery BAT2; the drain of the fourth switch Q4 is connected to the midpoint between the drain of the second switch Q2 and the neutral line N. The positive terminal of the second battery BAT2 is connected to the switching module.

4. The power conversion circuit according to claim 3, characterized in that, The switching module includes a first switch K1, a second switch K2, and a third switch K3; The first switch K1 is connected in series between the PFC inductor L1 and the mains live wire L; The second switch K2 is connected in series between the negative terminal of the first battery BAT1 and the PFC inductor L1; The third switch K3 is connected in series between the positive terminal of the second battery BAT2 and the PFC inductor L1.

5. The power conversion circuit according to claim 4, characterized in that, It also includes a control module; The control module is connected to the first switch K1, the second switch K2 and the third switch K3, and is used to control the on / off state of each switch.

6. The power conversion circuit according to claim 4, characterized in that, During the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is turned on. During the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is turned on.

7. The power conversion circuit according to claim 6, characterized in that, The positive half-cycle of the mains power mode includes a first phase and a second phase; In the first stage of the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is turned on. The current path is: mains live wire L - PFC inductor L1 - first switch Q1 - body diode of second switch Q2 - neutral wire N. In the second phase of the positive half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the first switch Q1 is opened. The current path is: mains live wire L-PFC inductor L1-first diode D1-positive bus capacitor C1-neutral line N. The negative half-cycle of the mains power mode includes a first phase and a second phase; In the first phase of the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is turned on. The current path is: neutral line N - second switch Q2 - body diode of the first switch Q1 - PFC inductor L1 - mains power line L. In the second phase of the negative half-cycle of the mains power mode, the first switch K1 is closed, the second switch K2 and the third switch K3 are opened, and the second switch Q2 is opened. The current path is: neutral line N - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - mains live wire L.

8. The power conversion circuit according to claim 4, characterized in that, During the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the first switch Q1 and the fourth switch Q4 are controlled to work together. During the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the second switch Q2 and the third switch Q3 are controlled to work together.

9. The power conversion circuit according to claim 8, characterized in that, The positive half-cycle of the battery mode includes a first phase and a second phase; In the first phase of the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the first switch Q1 and the fourth switch Q4 are turned on. The current path is: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - body diode of the first switch Q1 - fourth switch Q4 - negative terminal of the second battery BAT2. In the second phase of the positive half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the fourth switch Q4 is turned on. The current path is: positive terminal of the second battery BAT2 - third switch K3 - PFC inductor L1 - first diode D1 - positive bus capacitor C1 - fourth switch Q4 - negative terminal of the second battery BAT2. The negative half-cycle of the battery mode includes a first phase and a second phase; In the first stage of the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the second switch Q2 and the third switch Q3 are turned on. The current path is: positive terminal of the first battery BAT1 - third switch Q3 - second switch Q2 - body diode of the first switch Q1 - PFC inductor L1 - second switch K2 - negative terminal of the first battery BAT1. In the second phase of the negative half-cycle of the battery mode, the first switch K1 is opened, the second switch K2 and the third switch K3 are closed, and the third switch Q3 is turned on. The current path is: positive terminal of the first battery BAT1 - third switch Q3 - negative bus capacitor C2 - second diode D2 - PFC inductor L1 - second switch K2 - negative terminal of the first battery BAT1.

10. A UPS system, characterized in that, Includes the power conversion circuit as described in any one of claims 1-9.

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