A power supply circuit and uninterruptible power supply

Abstract

The application discloses a power supply circuit and an uninterruptible power supply, which comprises a commercial power access branch, a battery access branch and a rectifier unit; the battery access branch comprises a battery relay and a thyristor; the first end of the battery relay is connected with a battery power supply, and the second end thereof is connected with the input end of the rectifier unit; the first end of the thyristor is connected with the first end of the battery relay, and the second end thereof is connected with the second end of the battery relay; the commercial power access branch comprises a commercial power relay and a first capacitor; the first end of the commercial power relay is connected with a commercial power supply, and the second end thereof is connected with the second end of the battery relay; the first end of the first capacitor is connected with the first end of the commercial power relay, and the second end thereof is connected with the second end of the commercial power relay; when the commercial power relay is attracted, the first capacitor maintains the voltage continuity between the two ends of the commercial power relay, so as to inhibit the voltage change rate between the two ends of the thyristor. When the battery is switched to the commercial power, the voltage change rate between the two ends of the thyristor is inhibited by the first capacitor, so that the thyristor is prevented from being mis-conducted.

Description

Technical Field

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

[0002] With the rapid development of power electronics technology, power supply systems have been widely used in data centers, industrial automation, and new energy grid connection. These systems require reliable bidirectional switching between mains power and battery power modes. However, in existing power supply systems, during the switch from battery power to mains power, the potential of the thyristor in the battery input branch fluctuates after the relay in the battery input branch disconnects. Simultaneously, at the moment the relay in the mains input branch engages, the high voltage of the mains power instantaneously acts on the input of the rectifier unit. Since the mains input branch and the battery input branch share the same rectifier input node, the voltage jump generated at the moment the mains relay engages directly affects the battery input branch, resulting in an extremely high voltage change rate across the thyristor. This can easily lead to thyristor mis-conduction, causing a short circuit between the mains power and battery power, ultimately resulting in power supply circuit failure. Summary of the Invention

[0003] In view of the above problems, this application provides a power supply circuit to effectively prevent the thyristor from mis-energizing during the switching process from battery power to AC power. The specific solution is as follows:

[0004] This application provides a power supply circuit, comprising: a battery access branch including a battery relay and a thyristor; a first terminal of the battery relay serving as a first terminal of the battery access branch for connecting to a battery power source, and a second terminal of the battery relay serving as a second terminal of the battery access branch for connecting to the input terminal of a rectifier unit; a first terminal of the thyristor electrically connected to the first terminal of the battery relay, and a second terminal of the thyristor electrically connected to the second terminal of the battery relay; the battery relay receiving a first shutdown signal and disconnecting in response to the first shutdown signal.

[0005] The mains power access branch includes a mains power relay and a first capacitor; the first terminal of the mains power relay serves as the first terminal of the mains power access branch and is used to connect to the mains power supply, and the second terminal of the mains power relay serves as the second terminal of the battery access branch and is used to connect to the second terminal of the battery relay; the first terminal of the first capacitor is electrically connected to the first terminal of the mains power relay, and the second terminal of the first capacitor is electrically connected to the second terminal of the mains power relay; the mains power relay is used to receive a first turn-on signal and is energized in response to the first turn-on signal; the first capacitor is used to maintain the voltage across the mains power relay continuously when the mains power relay is energized, so as to suppress the voltage change rate across the thyristor.

[0006] In one possible implementation, the mains power access branch further includes a first resistor, which is connected in series with the first capacitor to form a first RC branch, and the first RC branch is connected across the two ends of the mains power relay; the battery access branch further includes a second capacitor and a second resistor, which are connected in series with the second capacitor to form a second RC branch, and the second RC branch is connected across the two ends of the thyristor.

[0007] The first RC branch and the second RC branch are used to divide the voltages of the mains power supply and the battery power supply when the mains relay is disconnected, so as to reduce the voltage stress across the mains relay; or,

[0008] The first RC branch and the second RC branch are used to divide the voltage of the mains power supply and the battery power supply when the battery relay is disconnected and the thyristor is turned off, so as to reduce the voltage stress on the two ends of the thyristor.

[0009] In one possible implementation, the system includes two mains power access branches and two battery access branches. The rectifier unit includes a first rectifier branch and a second rectifier branch connected in parallel at their output terminals. The input terminal of the first rectifier branch is connected to any phase of the mains power supply through one of its mains power access branches and to the positive terminal of the battery power supply through one of its battery access branches. The input terminal of the second rectifier branch is connected to the same phase of the mains power supply through the other mains power access branch and to the negative terminal of the battery power supply through the other battery access branch.

[0010] In one possible implementation, the rectifier unit includes two mains power access branches and two battery access branches. The rectifier unit includes a first rectifier branch and a second rectifier branch connected in parallel at their output terminals. The input terminal of the first rectifier branch is connected to a first phase of the mains power supply through one of its mains power access branches and to the positive terminal of the battery power supply through one of its battery access branches. The input terminal of the second rectifier branch is connected to a second phase of the mains power supply through the other mains power access branch and to the negative terminal of the battery power supply through the other battery access branch.

[0011] In one possible implementation, when the battery access branch is connected to the positive terminal of the battery power supply, the first end of the thyristor is the anode and the second end of the thyristor is the cathode; when the battery access branch is connected to the negative terminal of the battery power supply, the first end of the thyristor is the cathode and the second end of the thyristor is the anode.

[0012] In one possible implementation, the power supply circuit further includes a bus connected to the output of the rectifier unit; the first RC branch is also used to guide the AC power from the mains power supply to the bus via the rectifier unit to precharge the bus.

[0013] In one possible implementation, the power supply circuit further includes: a control module;

[0014] The control module is electrically connected to the mains power access branch and the battery access branch. The control module is used to send the first shutdown signal to the battery relay, and after sending the first shutdown signal, receive the phase detection signal of the mains power access branch, and send the first turn-on signal to the mains power relay according to the phase detection signal.

[0015] In one possible implementation, the control module is further configured to send a second shutdown signal to the mains relay to control the mains relay to disconnect; and

[0016] The control module is also used to send a second conduction signal to the thyristor and the battery relay when it receives the disconnection signal of the mains relay, so as to control the thyristor to conduct and control the battery relay to engage.

[0017] The time required for the thyristor to switch from an off state to an on state is less than the time required for the battery relay to switch from an off state to a closed state.

[0018] In one possible implementation, the power supply circuit further includes an inverter circuit;

[0019] The input terminal of the inverter circuit is connected to the output terminal of the bus, and the electrical output terminal of the inverter circuit is connected to the load device.

[0020] The inverter is used to convert the DC power stored on the bus into AC power and provide the AC power to the load device.

[0021] A second aspect of the present invention provides an uninterruptible power supply, including the circuit described in any of the preceding claims.

[0022] The power supply circuit provided by this application, using the above technical solution, includes a mains power input branch, a battery input branch, and a rectifier unit. The battery input branch includes a battery relay and a thyristor. The first terminal of the battery relay is connected to the battery power supply, and the second terminal of the battery relay is connected to the input terminal of the rectifier unit. The first terminal of the thyristor is connected to the first terminal of the battery relay, and the second terminal of the thyristor is connected to the second terminal of the battery relay. When the battery relay receives a first turn-off signal, it disconnects in response to the first turn-off signal. The mains power input branch includes a mains relay and a first capacitor. The first terminal of the mains relay is connected to the mains power supply, and the second terminal of the mains relay is connected to the second terminal of the battery relay. The first terminal of the first capacitor is connected to the first terminal of the mains relay, and the second terminal of the first capacitor is connected to the second terminal of the mains relay. When the mains relay receives a first turn-on signal, it engages in response to the first turn-on signal. When the mains relay is engaged, the first capacitor maintains a continuous voltage across the mains relay to suppress the rate of voltage change across the thyristor. When switching from battery power to AC power, this application uses a first capacitor to suppress the voltage change rate across the thyristor, effectively suppressing the thyristor's misleading conduction, thereby effectively preventing short circuit and common conduction between AC power and battery power, and the resulting power supply circuit failure. Attached Figure Description

[0023] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0024] Figure 1 A schematic diagram of a voltage waveform of a thyristor during switching, provided in this application;

[0025] Figure 2 A schematic diagram of a power supply circuit provided in this application;

[0026] Figure 3 A schematic diagram of another voltage waveform of the thyristor during switching provided in this application;

[0027] Figure 4 A schematic diagram of another power supply circuit provided in this application;

[0028] Figure 5 A schematic diagram of another power supply circuit provided in this application;

[0029] Figure 6 A schematic diagram of another power supply circuit provided in this application;

[0030] Figure 7 A schematic diagram of another power supply circuit provided in this application. Detailed Implementation

[0031] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0032] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0033] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, circuit, system, product, or device that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to those processes, circuits, products, or devices.

[0034] First, to facilitate understanding of this plan, some names need to be explained.

[0035] Thyristor: A semiconductor power switching device that is triggered to conduct by a gate signal. It is mainly used to perform high-speed current switching during the transition period of power switching to compensate for the action delay of mechanical switches.

[0036] Mains relay: An electromagnetic control switch deployed in the mains access branch, used to establish or physically disconnect the electrical connection between the external mains power supply and the downstream rectifier unit according to control commands.

[0037] Battery relay: An electromagnetic control switch deployed in the battery access branch, which works in parallel with a thyristor to achieve safe connection or isolation between the battery power supply and the back-end shared node.

[0038] Reusable topology: Different energy branches share the same core power conversion unit and magnetic components to achieve a circuit structure that is compatible with multiple energy modes while reducing hardware size.

[0039] Secondly, to facilitate understanding of the technical solutions provided in the embodiments of this application by those skilled in the art, the relevant technologies are described below.

[0040] In existing reuse topologies, bidirectional switching between AC power and battery power modes is primarily achieved through AC relays and battery relays. When the system switches from battery power to AC power, the battery relay first disconnects, followed by the AC relay engaging. However, at the instant the AC relay engages, because the second terminal of the SCR is directly connected to the second terminal of the AC relay, the SCR's potential abruptly changes from a floating state to the AC voltage, causing the voltage change rate across the SCR to far exceed its critical value. This voltage jump can cause the SCR to mis-conduct, creating a severe short-circuit common-conductance path between the AC and battery input branches. Figure 1 As shown, in the process of switching from battery power to AC power, the voltage waveform across the thyristor in the existing multiplexing topology exhibits an extremely steep rising edge, resulting in a voltage step transition.

[0041] To address the aforementioned problems, this application provides a power supply circuit. The power supply circuit of this application embodiment will be described in detail below with reference to the accompanying drawings.

[0042] Firstly, referring to Figure 2 , Figure 2 This is a schematic diagram of a power supply circuit provided in an embodiment of this application, such as... Figure 2 As shown, the power supply circuit includes: a mains power input branch, a battery input branch, and a rectifier unit. The battery input branch includes a battery relay and a thyristor. The first terminal of the battery relay serves as the first terminal of the battery input branch, used to connect to the battery power supply; the second terminal of the battery relay serves as the second terminal of the battery input branch, used to connect to the input terminal of the rectifier unit. The first terminal of the thyristor is electrically connected to the first terminal of the battery relay, and the second terminal of the thyristor is electrically connected to the second terminal of the battery relay. The battery relay receives a first turn-off signal and disconnects in response to the first turn-off signal. The mains power input branch includes a mains relay and a first capacitor. The first terminal of the mains relay serves as the first terminal of the mains power input branch, used to connect to the mains power supply; the second terminal of the mains relay serves as the second terminal of the battery input branch, used to connect to the second terminal of the battery relay. The first terminal of the first capacitor is electrically connected to the first terminal of the mains relay, and the second terminal of the first capacitor is electrically connected to the second terminal of the mains relay. The mains relay receives a first turn-on signal and engages in response to the first turn-on signal. The first capacitor is used to maintain the voltage across the mains relay when the mains relay is energized, so as to suppress the voltage change rate across the thyristor.

[0043] Specifically, battery relay (corresponding to) Figure 2 RLYA in the middle) and mains relay (corresponding to Figure 2 The RLYB in the text can be an electromagnetic relay or a solid-state relay, etc. A thyristor (corresponding to...) Figure 2 The SCR (Silicon Controlled Rectifier) ​​in the circuit can be either a unidirectional or bidirectional SCR, depending on the current direction requirements of the power supply circuit. The AC power supply can be single-phase or three-phase AC. The battery power supply can be a lead-acid battery pack, lithium battery pack, etc.

[0044] During the switching process from battery power to AC power in the power supply circuit, the battery relay receives a first shutdown signal and disconnects in response. The AC power relay receives a first turn-on signal and turns on in response. There may be a certain time difference between the battery relay receiving the first shutdown signal and the AC power relay receiving the first turn-on signal. For example, the battery relay may receive the first shutdown signal first, and only after the battery relay performs the shutdown operation does it send the first turn-on signal to the AC power relay.

[0045] When the battery relay is on (while the mains relay is off), the voltage difference across the thyristor is zero. The potential across the thyristor is the same as the potential at the second terminal of the mains relay. When the mains relay is off, there is a voltage difference across it. When the battery relay disconnects in response to the first off signal and the mains relay remains off without receiving the first on signal, the first capacitor is discharging, maintaining a continuous voltage across the mains relay connected in parallel with the first capacitor. When the mains relay receives the first on signal and immediately turns on, the voltage difference across the capacitor (the first capacitor) gradually decreases due to the parallel connection, preventing a sudden change in the potential at the second terminal of the mains relay to the mains voltage. Since the second terminal of the thyristor is electrically connected to the second terminal of the mains relay, according to the circuit topology, the potential at the second terminal of the thyristor is always equal to the potential at the second terminal of the mains relay and will not change abruptly. Therefore, connecting a first capacitor in parallel across the mains relay can effectively suppress the voltage change rate across the thyristor during the switch from battery power to mains power, thereby significantly reducing the risk of the thyristor mis-energizing due to excessive voltage change rate. Figure 3 As shown, by connecting the first capacitor in parallel across the mains relay, the voltage transition across the thyristor can exhibit a smooth transition characteristic, and its rising slope is significantly reduced.

[0046] In some embodiments, a voltage detection circuit can be added across the thyristor. This circuit acquires the voltage difference across the thyristor. Only when the voltage difference exceeds a preset threshold is a first turn-on signal sent to the mains relay, effectively preventing a common-conductor short circuit caused by the mains relay prematurely engaging before the battery relay disconnects. In some embodiments, during battery power supply, the mains connection point can be located inside the machine. In non-maintenance situations, the user cannot directly contact this mains connection point, and adding a capacitor branch does not increase the risk of electric shock. Secondly, utilizing the electrical characteristics of the first capacitor (blocking DC and passing AC), only a small amount of AC component of the DC output from the battery power supply will be transmitted to the mains connection point through the capacitor branch, while the main DC current cannot be transmitted to the mains connection point through the capacitor, further eliminating the potential electric shock hazard caused by DC potential rise at the mains connection point. Finally, as... Figure 2 As shown, a filter circuit can be set between the mains power supply and the first capacitor. Specifically, the first terminal of the filter circuit is connected to the mains power supply, and the second terminal is connected to the mains relay. This filter circuit and the first capacitor form a voltage divider network. In battery-powered mode, the AC component generated in the power supply circuit will pass through this voltage divider network, thereby controlling the voltage at the mains connection point to a lower, safer voltage level, effectively ensuring electrical safety in battery-powered mode. The filter circuit includes a parallel filter capacitor (corresponding to...). Figure 2 Cb) and inductance (corresponding to Figure 2 (L in the original text). The capacitance of the first capacitor is greater than that of the filter capacitor. For example, the ratio of the capacitance of the filter capacitor to that of the first capacitor can be 50, 90, 100, 200, 500, etc., specifically 20uF:220nF.

[0047] In this embodiment, by connecting a first capacitor in parallel across the mains relay, the voltage across the first capacitor is kept constant during the mains relay's activation process, thus suppressing the voltage change rate across the connected thyristor and effectively reducing the risk of false activation caused by voltage fluctuations during the switching process.

[0048] In one possible implementation, such as Figure 4As shown, the mains power input branch also includes a first resistor. The first resistor and the first capacitor are connected in series to form a first RC branch, which is connected across the mains relay. The battery input branch also includes a second capacitor and a second resistor. The second resistor and the second capacitor are connected in series to form a second RC branch, which is connected across the thyristor. The first RC branch and the second RC branch are used to divide the voltage of the mains power supply and the battery power supply when the mains relay is off, so as to reduce the voltage stress on the mains relay. Alternatively, the first RC branch and the second RC branch are used to divide the voltage of the mains power supply and the battery power supply when the battery relay is off and the thyristor is off, so as to reduce the voltage stress on the thyristor.

[0049] Specifically, such as Figure 4 As shown, both the number of mains power input branches and the number of battery input branches can be one. In this case, the rectifier unit can be a single rectifier branch (e.g., the first rectifier branch). The rectifier branch can be a Vienna topology circuit, etc., and is not limited here. The mains power input branch may include a first mains relay (corresponding to...). Figure 4 RLY1), the battery access branch may include a first battery relay (corresponding to Figure 4 RLY2) and the first thyristor (corresponding to Figure 4 The SCR1 is a first mains relay. The first terminal of the first mains relay is connected to the mains power supply, and the second terminal of the first mains relay is connected to the rectifier unit. The first terminal of the first battery relay can be connected to the battery power supply. The first terminal of the first battery relay is connected to the second terminal of the first mains relay. The first terminal of the first thyristor is connected to the first terminal of the first battery relay, and the second terminal of the first thyristor is connected to the second terminal of the first battery relay. It should be noted that the first terminal of the first battery relay can be selectively connected to the positive or negative terminal of the battery power supply. Depending on the connection point of the first terminal of the first battery relay, the installation polarity (direction of anode and cathode) of the first thyristor connected in parallel with it also needs to be adjusted accordingly. The specific connection method between the battery relay and the thyristor will be described in the following embodiments and will not be repeated here.

[0050] First resistor (corresponding to) Figure 4 R1 in the middle) and the first capacitor (corresponding to Figure 4 The first RC branch is formed by connecting C1 in series, and then the first RC branch is connected across the two ends of the first mains relay. Meanwhile, the second resistor (corresponding to...) Figure 4 R2 in the middle) and the second capacitor (corresponding to Figure 4The first capacitor (C2) is connected in series to form a second RC branch, which is then connected across the first thyristor. When the first mains relay is off, the first and second RC branches work together to divide the voltage between the mains power supply and the battery power supply, reducing the voltage stress across the first mains relay and thus helping to protect the contacts of the first mains relay from arcing or insulation damage due to excessive voltage difference. When the first battery relay is off and the first thyristor is in the off state, the first and second RC branches work together to divide the voltage between the mains power supply and the battery power supply, reducing the voltage stress across the first thyristor and thus helping to prevent the first thyristor from breaking down due to overvoltage. Furthermore, when the first mains relay is energized, the first capacitor can also be used to maintain the voltage continuity across the first mains relay to suppress the rate of voltage change across the first thyristor. When the first mains relay is energized, the second capacitor can also be used to absorb the voltage spikes generated when the first thyristor is turned off. Specifically, at the instant the first battery relay and the first thyristor are turned off, a reverse voltage spike is formed in the circuit consisting of the battery power supply, the first battery relay and the first thyristor and acts on the first thyristor. At this time, the second capacitor reduces the amplitude of the reverse voltage spike by suppressing the reverse voltage spike.

[0051] When selecting the first and second capacitors, the following steps can be followed: First, determine the capacitance value of the second capacitor connected in parallel across the first thyristor. The capacitance value of the second capacitor can be selected within a preset range, for example, 0.5nF to 10nF. After determining the capacitance value of the second capacitor, determine the capacitance value of the first capacitor connected in parallel across the first mains relay. The capacitance value of the first capacitor needs to be designed considering the amplitude of the mains voltage and the switching time required for the battery relay to switch to the mains relay. In practical applications, the specific capacitance value of the first capacitor can be determined through circuit debugging. The capacitance ratio of the first capacitor to the second capacitor must ensure that during the switching process from battery power to mains power, the discharge current generated at the moment the first mains relay engages is insufficient to cause arc melting at its contacts, and the rate of voltage change applied across the first thyristor is lower than the withstand value of the first thyristor. In this embodiment, the withstand value of the first thyristor can be 1500V / μs. The capacitance value range of the first capacitor can be 100nF to 300nF, and the capacitance value range of the second capacitor can be 0.5nF to 10nF. Therefore, the capacitance ratio of the second capacitor to the first capacitor ranges from approximately 1 / 600 to 1 / 10.

[0052] In this embodiment, by connecting a first RC branch in parallel across the mains relay and a second RC branch in parallel across the thyristor, the voltage stress across the mains relay contacts can be reduced when the mains relay is disconnected, and the voltage stress across the thyristor contacts can be reduced when the thyristor is disconnected.

[0053] The power supply circuit described above includes one AC power input branch and one battery input branch. To improve the reliability of the system's power supply, the number of AC power input branches and battery input branches can also be multiple. The following explanation uses two AC power input branches and two battery input branches as an example.

[0054] In one possible implementation, the power supply circuit may include two AC power input branches and two battery input branches. The rectifier unit includes a first rectifier branch and a second rectifier branch with their outputs connected in parallel. The input of the first rectifier branch is connected to any phase of the AC power supply through one of its AC power input branches and to the positive terminal of the battery power supply through one of its battery input branches. The input of the second rectifier branch is connected to the same phase of the AC power supply through the other AC power input branch and to the negative terminal of the battery power supply through the other battery input branch.

[0055] Specifically, such as Figure 5 As shown, there can be two mains power access branches and two battery access branches. In this case, one of the mains power access branches may include a first mains power relay (corresponding to...). Figure 5 RLY1 in the middle), the first capacitor (corresponding to Figure 5 C1) and the first resistor (corresponding to Figure 5 In R1), another mains power input branch may include a second mains power relay (corresponding to R1). Figure 5 RLY3 in the middle), the third capacitor (corresponding to Figure 5 C3) and the third resistor (corresponding to Figure 5 R3 in the diagram). One of the battery access branches may include a first battery relay (corresponding to R3 in the diagram). Figure 5 RLY2 in the middle), the first thyristor (corresponding to Figure 5 SCR1), the second capacitor (corresponding to) Figure 5 C2) and the second resistor (corresponding to Figure 5 R2 in the diagram). Another battery access branch may include a second battery relay (corresponding to R2). Figure 5 RLY4 in the middle), the second thyristor (corresponding to Figure 5 SCR2 in the middle), the fourth capacitor (corresponding to Figure 5 C4) and the fourth resistor (corresponding to Figure 5 (R4 in the middle).

[0056] The first terminal of the first mains relay is connected to any phase of the mains power supply (corresponding to...). Figure 5In the circuit, IN_A), the second terminal of the first mains relay is connected to the first rectifier branch. The first terminal of the first battery relay can be connected to the positive terminal of the battery power supply. The second terminal of the first battery relay is connected to the second terminal of the first mains relay. The first terminal (anode) of the first thyristor is connected to the first terminal of the first battery relay, and the second terminal (cathode) of the first thyristor is connected to the second terminal of the first battery relay.

[0057] The first terminal of the second mains relay is connected to the same phase of the mains power supply (corresponding to...). Figure 5 The second terminal of the second AC relay (IN_A) is connected to the second rectifier branch. The first terminal of the second battery relay can be connected to the negative terminal of the battery power supply. The first terminal of the second battery relay is connected to the second terminal of the second AC relay. The second terminal (cathode) of the second thyristor is connected to the first terminal of the second battery relay, and the first terminal (anode) of the second thyristor is connected to the second terminal of the second battery relay.

[0058] A first RC branch, formed by a first resistor and a first capacitor, can be connected across the first mains relay. A second RC branch, formed by a second resistor and a second capacitor, can be connected across the first thyristor. When the first mains relay is open, the first and second RC branches work together to divide the voltage between the mains power supply and the battery power supply, reducing the voltage stress across the first mains relay and thus helping to protect the contacts of the first mains relay from arcing or insulation damage due to excessive voltage difference. When the first battery relay is open and the first thyristor is in the off state, the first and second RC branches work together to divide the voltage between the mains power supply and the battery power supply, reducing the voltage stress across the first thyristor and thus helping to prevent the first thyristor from breaking down due to overvoltage. Furthermore, when the first mains relay is engaged, the first capacitor can also be used to maintain the voltage continuity across the first mains relay, suppressing the rate of voltage change across the first thyristor.

[0059] A third resistor and a third capacitor can be connected in series to form a third RC branch, which is then connected across the second AC relay. A fourth resistor and a fourth capacitor can be connected in series to form a fourth RC branch, which is then connected across the second SCR. When the second AC relay is open, the third and fourth RC branches work together to divide the voltage between the AC power supply and the battery power supply, reducing the voltage stress across the second AC relay and thus helping to protect the relay contacts from arcing or insulation damage due to excessive voltage differences. When the second battery relay is open and the second SCR is in the off state, the third and fourth RC branches work together to divide the voltage between the AC power supply and the battery power supply, reducing the voltage stress across the second SCR and thus helping to prevent the SCR from breaking down due to overvoltage. Furthermore, when the second AC relay is energized, the third capacitor can also be used to maintain the voltage continuity across the second AC relay, suppressing the rate of voltage change across the second SCR.

[0060] The selection method for the third and fourth capacitors is similar to that for the first and second capacitors. Specifically, the capacitance value of the third capacitor connected in parallel across the second thyristor can be determined first. The capacitance value of the third capacitor can be selected within a preset range, for example, 0.5nF to 10nF. After determining the capacitance value of the third capacitor, the capacitance value of the fourth capacitor connected in parallel across the second mains relay is then determined. The capacitance value of the third capacitor needs to be designed considering the amplitude of the mains voltage and the switching time required for the battery relay to switch to the mains relay. In practical applications, the specific capacitance value of the third capacitor can be determined through circuit debugging. The ratio of the capacitance values ​​of the third and fourth capacitors must ensure that during the switching process from battery power to mains power, the discharge current generated at the moment the second mains relay engages is insufficient to cause arc melting at its contacts, and the rate of voltage change applied across the second thyristor is lower than the withstand value of the second thyristor. In this embodiment, the withstand value of the second thyristor can be 1500V / μs. The capacitance value of the third capacitor can range from 100nF to 300nF, and the capacitance value of the fourth capacitor can range from 0.5nF to 10nF. Therefore, the capacitance ratio of the third capacitor to the fourth capacitor is approximately 1 / 600 to 1 / 10.

[0061] In this embodiment, the rectifier unit includes a first rectifier branch and a second rectifier branch connected in parallel at their output terminals. The input terminal of the first rectifier branch is connected to a phase of the mains power supply through a mains access branch and to the positive terminal of the battery power supply through a battery access branch; the input terminal of the second rectifier branch is connected to the same phase of the mains power supply through another mains access branch and to the negative terminal of the battery power supply through another battery access branch, thereby enhancing the reliability and stability of the power supply.

[0062] The aforementioned embodiments connect two AC power access branches to the same phase of the AC power supply. Embodiments of this application may also connect two AC power access branches to different phases of the AC power supply; exemplary embodiments are provided below for illustration.

[0063] In one possible implementation, the power supply circuit further includes two AC power input branches and two battery input branches. The rectifier unit includes a first rectifier branch and a second rectifier branch with their output terminals connected in parallel. The input terminal of the first rectifier branch is connected to the first phase of the AC power supply through one AC power input branch and to the positive terminal of the battery power supply through one battery input branch. The input terminal of the second rectifier branch is connected to the second phase of the AC power supply through another AC power input branch and to the negative terminal of the battery power supply through another battery input branch.

[0064] Specifically, the first phase of the mains power supply (corresponding to...) Figure 6 IN_A in the second phase (corresponding to) Figure 6 IN_B in the equation can be any two phases of a three-phase AC power supply. The first and second rectifier branches can each be independent full-bridge rectifiers. Alternatively, the first and second rectifier branches can share some rectifier components, forming a rectifier bridge topology suitable for two-phase input. By connecting the two AC power input branches to different phases of the AC power supply, the power supply circuit can utilize the line voltage between the two phases (e.g., 380V) for rectification, thereby obtaining a higher DC bus voltage after rectification and improving the overall power supply circuit's power capability.

[0065] In this embodiment, the first rectifier branch is connected to the first phase of the mains power and the positive terminal of the battery, and the second rectifier branch is connected to the second phase of the mains power and the negative terminal of the battery, forming a dual-path symmetrical input of the mains power and the battery, thereby effectively avoiding single-phase overload and facilitating the three-phase balance of the power grid.

[0066] In one possible implementation, when the battery access branch is connected to the positive terminal of the battery power supply, the first terminal of the thyristor is the anode, and the second terminal of the thyristor is the cathode. When the battery access branch is connected to the negative terminal of the battery power supply, the first terminal of the thyristor is the cathode, and the second terminal of the thyristor is the anode.

[0067] Specifically, when the battery connection branch needs to be connected to the positive terminal of the battery power supply, the anode of the thyristor (i.e., the current inflow terminal) is used as the first terminal of the thyristor and connected to the positive terminal of the battery power supply. The cathode of the thyristor (i.e., the current outflow terminal) is used as the second terminal of the thyristor and connected to the input terminal of the rectifier unit. This ensures that the thyristor can conduct in the forward direction in battery-powered mode, allowing current to flow from the positive terminal of the battery power supply through the anode of the thyristor and out through the cathode.

[0068] When the battery connection branch requires connection to the negative terminal of the battery power supply, the cathode of the thyristor is used as the first terminal of the thyristor and connected to the negative terminal of the battery power supply. The anode of the thyristor is used as the second terminal of the thyristor and connected to the input terminal of the rectifier unit. This ensures that the thyristor can conduct in the forward direction in battery-powered mode, allowing current to flow from the input terminal of the rectifier unit through the anode of the thyristor and out through the cathode to the negative terminal of the battery power supply.

[0069] In this embodiment, if the battery connection branch is connected to the positive terminal of the battery, the anode of the thyristor is connected towards the side of the battery power source. If the battery connection branch is connected to the negative terminal of the battery, the cathode of the thyristor is connected towards the side of the battery power source, thereby effectively preventing the thyristor from burning out or malfunctioning.

[0070] In some embodiments, the battery access branch may also include a fuse, which is connected in series in the battery access branch to melt and disconnect the electrical connection between the battery power supply and the rectifier unit when an overcurrent or short circuit fault occurs in the battery access branch, thereby protecting the battery power supply and the rectifier unit from damage caused by high current surges.

[0071] In one possible implementation, the power supply circuit also includes a busbar connected to the output of the rectifier unit. The first RC branch is also used to guide AC power from the mains power supply through the rectifier unit to the busbar for pre-charging.

[0072] Specifically, such as Figure 7 As shown, a busbar can include a positive busbar (corresponding to...) Figure 7 BUS+ in the middle), negative bus (corresponding to Figure 7 (Middle BUS-) and bus midpoint (corresponding to) Figure 7 The O in the diagram). The midpoint of the busbar and the neutral wire of the mains power supply (corresponding to...). Figure 7 The connection is as follows: (N) . A positive bus capacitor can be connected between the positive bus and the midpoint of the bus. A negative bus capacitor can be connected between the midpoint of the bus and the negative bus. The positive bus capacitor can be a single capacitor or multiple capacitors connected in parallel. The negative bus capacitor can be a single capacitor or multiple capacitors connected in parallel.

[0073] When there is only one AC mains power access branch, it is connected across the first AC mains relay via a first RC branch. When the first AC mains relay is not engaged, the first RC branch provides a bypass path with resistance and capacitance for the AC mains power supply. The AC power enters the rectifier unit via the first RC branch, is rectified into DC power, and then sent to the bus.

[0074] With two mains power access branches, the first and third RC branches are connected across the first and second mains relays, respectively. When the first and second mains relays are not engaged, the first and third RC branches provide bypass paths with resistors and capacitors for the AC power from the mains power supply. The AC power enters the rectifier unit via the first and third RC branches, is rectified into DC power, and then sent to the bus. The first and third resistors limit the amplitude of the charging current, and the first and third capacitors slow down the rate of voltage change, allowing the bus voltage to gradually increase.

[0075] In this embodiment, the first RC branch and the second RC branch provide a current-limiting conduction path when the first mains relay and the second mains relay are disconnected, so that the AC power from the mains power supply can slowly precharge the bus through the rectifier unit, thereby shortening the power-on preparation time, reducing the energy loss caused by direct charging, and effectively preventing the melting of the contacts of the first mains relay and the second mains relay caused by discharge during the charging process of the bus.

[0076] In one possible implementation, the power supply circuit may further include a control module. The control module is electrically connected to the mains power input branch and the battery input branch. The control module is used to send a first shutdown signal to the battery relay, and after sending the first shutdown signal, to receive a phase detection signal of the mains power input branch, and to send a first turn-on signal to the mains power relay according to the phase detection signal.

[0077] Specifically, the control module can be a microcontroller module, a single-chip microcomputer control module, a digital signal processor, or a control module based on programmable logic control. A phase detection circuit can detect the voltage phase of the AC mains input branch and send a phase detection signal to the control module. The control module determines a specific phase position (e.g., zero-crossing moment) of the AC mains voltage waveform within one cycle based on the phase detection signal, and sends a first turn-on signal to the first and second AC mains relays at that specific phase position.

[0078] In this embodiment, after the control module sends a first shutdown signal to the battery access branch, it controls the opening of the first mains relay and the second mains relay based on the phase detection signal of the mains access branch. This can effectively avoid contact erosion or device overload of the first and second mains relays at the moment of engagement, thereby improving the safety and stability of the power supply switching process.

[0079] In one possible implementation, the control module is further configured to send a second turn-off signal to the mains relay to control the mains relay to turn off. The control module is also configured to, upon receiving the turn-off signal from the mains relay, send a second turn-on signal to the thyristor and the battery relay to control the thyristor to turn on and simultaneously control the battery relay to engage. The time required for the thyristor to switch from an off state to a on state is less than the time required for the battery relay to switch from an off state to a closed state.

[0080] Specifically, during the switching process from battery power to AC power, the control module can send a second shutdown signal to the AC relay to control its disconnection. When both AC relays are detected as disconnected, a second turn-on signal can be sent simultaneously to the thyristor and the battery relay. Since the time required for the thyristor to switch from an off state to a on state is shorter than the time required for the battery relay to switch from an off state to a closed state, the thyristor turns on earlier than the battery relay. Therefore, by configuring the thyristor, after disconnecting the rectifier unit from the AC power supply, a rapid connection between the battery power supply and the rectifier unit can be achieved, thus realizing uninterrupted switching of the power supply circuit from battery power to AC power.

[0081] In this embodiment, when switching from AC power to battery power, the AC power relay is first disconnected, and then a second conduction signal is sent to the thyristor and the battery relay simultaneously. Taking advantage of the fact that the conduction speed of the thyristor is faster than the closing speed of the battery relay, the thyristor quickly establishes a temporary current path before the battery relay is fully closed, thereby realizing a seamless switch from AC power supply to battery power supply and effectively preventing the interruption of load power supply during the switching process.

[0082] In one possible implementation, such as Figure 7 As shown, the input terminal of the inverter circuit is connected to the output terminal of the bus, and the electrical output terminal of the inverter circuit is connected to the load device. The inverter is used to convert the DC power stored on the bus into AC power and provide the AC power to the load device.

[0083] Specifically, inverter circuits can include three-level inverters, half-bridge inverters, single-phase full-bridge inverters, three-phase full-bridge inverters, etc. Load devices can include servers, routers, switches, personal computers, base station equipment, transmission equipment, etc.

[0084] In this embodiment, the DC power stored on the bus is converted into AC power by an inverter circuit and supplied to the load equipment, thereby achieving efficient DC-AC energy conversion and meeting the needs of normal load operation.

[0085] In some embodiments, the power supply circuit may further include a charging and discharging circuit. This charging and discharging circuit may be a shared charging equalization bridge circuit, etc. The charging and discharging circuit is electrically connected between the bus and the battery access branch. The charging and discharging circuit is used to charge the battery when powered by mains power, to temporarily supply power to the bus when switching between mains power and battery power, and to regulate the bus voltage balance when powered by battery power.

[0086] Secondly, embodiments of this application provide an uninterruptible power supply (UPS). This UPS may include the power supply circuit described in any embodiment of the first aspect.

[0087] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0088] The above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of the embodiments of this application.

Claims

1. A power supply circuit, characterized in that, include: Mains power input branch, battery input branch, and rectifier unit; The battery access branch includes a battery relay and a silicon controlled rectifier (SCR); the first terminal of the battery relay serves as the first terminal of the battery access branch and is used to connect to the battery power supply, and the second terminal of the battery relay serves as the second terminal of the battery access branch and is used to connect to the input terminal of the rectifier unit; the first terminal of the SCR is electrically connected to the first terminal of the battery relay, and the second terminal of the SCR is electrically connected to the second terminal of the battery relay; the battery relay is used to receive a first shutdown signal and disconnect in response to the first shutdown signal. The mains power access branch includes a mains power relay and a first capacitor; the first terminal of the mains power relay serves as the first terminal of the mains power access branch and is used to connect to the mains power supply, and the second terminal of the mains power relay serves as the second terminal of the battery access branch and is used to connect to the second terminal of the battery relay; the first terminal of the first capacitor is electrically connected to the first terminal of the mains power relay, and the second terminal of the first capacitor is electrically connected to the second terminal of the mains power relay; the mains power relay is used to receive a first turn-on signal and is energized in response to the first turn-on signal; the first capacitor is used to maintain the voltage across the mains power relay continuously when the mains power relay is energized, so as to suppress the voltage change rate across the thyristor.

2. The circuit according to claim 1, characterized in that, The mains power input branch also includes a first resistor, which is connected in series with the first capacitor to form a first RC branch, and the first RC branch is connected across the two ends of the mains power relay; the battery input branch also includes a second capacitor and a second resistor, which are connected in series with the second capacitor to form a second RC branch, and the second RC branch is connected across the two ends of the thyristor. The first RC branch and the second RC branch are used to divide the voltages of the mains power supply and the battery power supply when the mains relay is disconnected, so as to reduce the voltage stress across the mains relay; or, The first RC branch and the second RC branch are used to divide the voltage of the mains power supply and the battery power supply when the battery relay is disconnected and the thyristor is turned off, so as to reduce the voltage stress on the two ends of the thyristor.

3. The circuit according to claim 2, characterized in that, include: The rectifier unit includes two mains power input branches and two battery input branches. The output terminals of the rectifier branch are connected in parallel to a first rectifier branch and a second rectifier branch. The input terminal of the first rectifier branch is connected to any phase of the mains power supply through one of its mains power input branches and to the positive terminal of the battery power supply through one of its battery input branches. The input terminal of the second rectifier branch is connected to the same phase of the mains power supply through the other mains power input branch and to the negative terminal of the battery power supply through the other battery input branch.

4. The circuit according to claim 2, characterized in that, The rectifier unit includes two mains power input branches and two battery input branches. The rectifier unit includes a first rectifier branch and a second rectifier branch connected in parallel at their output terminals. The input terminal of the first rectifier branch is connected to the first phase of the mains power supply through one of its mains power input branches and to the positive terminal of the battery power supply through one of its battery input branches. The input terminal of the second rectifier branch is connected to the second phase of the mains power supply through the other mains power input branch and to the negative terminal of the battery power supply through the other battery input branch.

5. The circuit according to claim 3 or 4, characterized in that, When the battery access branch is connected to the positive terminal of the battery power supply, the first end of the thyristor is the anode and the second end of the thyristor is the cathode; when the battery access branch is connected to the negative terminal of the battery power supply, the first end of the thyristor is the cathode and the second end of the thyristor is the anode.

6. The circuit according to claim 2, characterized in that, It also includes a busbar connected to the output of the rectifier unit; the first RC branch is also used to guide the AC power from the mains power supply to the busbar via the rectifier unit to precharge the busbar.

7. The circuit according to claim 1, characterized in that, Also includes: Control module; The control module is electrically connected to the mains power access branch and the battery access branch. The control module is used to send the first shutdown signal to the battery relay, and after sending the first shutdown signal, receive the phase detection signal of the mains power access branch, and send the first turn-on signal to the mains power relay according to the phase detection signal.

8. The circuit according to claim 7, characterized in that, The control module is further configured to send a second shutdown signal to the mains relay to control the mains relay to disconnect; and The control module is also used to send a second conduction signal to the thyristor and the battery relay when it receives the disconnection signal of the mains relay, so as to control the thyristor to conduct and control the battery relay to engage. The time required for the thyristor to switch from an off state to an on state is less than the time required for the battery relay to switch from an off state to a closed state.

9. The circuit according to claim 1, characterized in that, Also includes: Inverter circuit; The input terminal of the inverter circuit is connected to the output terminal of the bus, and the electrical output terminal of the inverter circuit is connected to the load device. The inverter is used to convert the DC power stored on the bus into AC power and provide the AC power to the load device.

10. An uninterruptible power supply, characterized in that, The circuit includes any one of claims 1 to 9.

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