Backflow detection circuit and power supply device
By combining current transformers, impedance modules, and amplifiers, the problem of high cost and easy damage of reverse backflow detection devices in high-power power supply scenarios is solved, and safe and reliable reverse backflow fault detection is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- EMERSON NETWORK POWER CO LTD
- Filing Date
- 2025-04-28
- Publication Date
- 2026-05-26
AI Technical Summary
In high-power power supply scenarios, backflow detection devices are costly and the components are easily damaged, making it difficult for existing technologies to effectively protect the device's safety.
The design employs a combination of current transformers, impedance modules, and amplifiers. The current transformers detect electrical parameters, and the impedance modules limit the current before outputting the data to the amplifier. The amplifier amplifies the data to detect reverse-current faults. The impedance modules are added to increase the total impedance of the secondary winding and protect the devices.
This reduces the cost of backflow detection devices while protecting device safety and improving detection stability and reliability.
Smart Images
Figure CN224289305U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power electronics technology, and in particular to a reverse feedwater detection circuit and power supply device. Background Technology
[0002] Reverse current flow, overload, and short circuit are common fault types detected in power supply applications. As power module power increases, the requirements for the size and cost of fault detection devices become increasingly stringent. Due to the increased current amplitude on the power module's lines, the output current amplitude is large when the line current sampled by the current transformer is coupled to the secondary winding side through the magnetic core, which can easily damage the downstream detection and processing devices. To ensure detection safety, more expensive devices must be configured to meet the reverse current flow detection requirements in high-power power supply scenarios. Utility Model Content
[0003] This application provides a backflow detection circuit and power supply device to meet the backflow fault detection requirements of equipment in high-power power supply scenarios and reduce the cost of backflow detection devices.
[0004] In a first aspect, embodiments of this application provide a backflow detection circuit, which can be applied to high-power power supply equipment and used to determine whether a backflow fault has occurred in the equipment. The backflow detection circuit may include: a current transformer, an impedance module, and an amplifier.
[0005] The primary winding of the current transformer is connected to the branch under test, and the secondary winding of the current transformer is connected to the impedance module. The current transformer is used to detect the electrical parameters on the branch under test and output the detected values to the impedance module. The impedance module is connected to the processing device through the amplifier. The impedance module is used to receive the electrical parameters output by the current transformer, and output the detected electrical parameters to the amplifier after current limiting. The amplifier is used to amplify the electrical parameters output by the impedance module and output them to the processing device, so that the processing device can perform reverse-current fault detection based on the electrical parameters output by the amplifier.
[0006] Using the above design, the transformer in the reverse-current detection circuit can be a current transformer. The primary winding of the current transformer is connected in series in the branch under test, and the secondary winding of the current transformer is transmitted to the processing device through an impedance module and an amplifier. The branch under test can be a bypass branch of the power supply device. When the main circuit is powered, no current flows through the bypass branch. If current is detected in the primary winding of the current transformer during this period, the processing device can use this current for reverse-current fault detection. When the bypass branch is powered, due to the large amplitude of the normal power supply current, the output current amplitude of the secondary winding of the current transformer may be large and may cause device damage. The configured impedance module can limit the current before outputting it to the downstream device, thereby meeting the reverse-current fault detection requirements of the power supply device and ensuring device safety. Since only one impedance module is added to meet the detection requirements of a high-power power supply device, it also helps to reduce the cost of the reverse-current detection device.
[0007] The secondary current of a current transformer is mainly determined by the secondary voltage and the total impedance on the secondary side. By configuring an impedance module to increase the total impedance on the secondary side, the amplitude of the secondary current of the current transformer is limited, thereby protecting the safety of the secondary-side components. Compared to the existing technology that adjusts the secondary winding components, only additional impedance components are needed to meet the reverse current detection requirements in high-power power supply scenarios, resulting in lower costs.
[0008] In one possible design, the impedance module includes a first resistor, with a first terminal connected to a first interface of the secondary winding of the current transformer, and a second terminal connected to a first input terminal of the amplifier; the second interface of the secondary winding of the current transformer is connected to a second input terminal of the amplifier. With this design, a first resistor is configured on the path between the secondary winding of the current transformer and the amplifier. Because the total impedance on the secondary winding side is increased, the amplitude of the secondary current can ensure the safety of downstream devices even without changing the parameters of the current transformer.
[0009] In one possible design, if the current limiting capability of a single resistor cannot meet the backflow detection requirements of high-power power supply equipment, the impedance module further includes a second resistor connected between the second interface of the secondary winding of the current transformer and the second input terminal of the amplifier. The first end of the second resistor is connected to the second interface of the secondary winding of the current transformer, and the second end of the second resistor is connected to the second input terminal of the amplifier.
[0010] In one possible design, the reverse flow detection circuit further includes a first diode and a second diode.
[0011] In this configuration, the anode of the first diode is connected to the first input terminal of the amplifier, and the cathode of the first diode is connected to the second input terminal of the amplifier; the cathode of the second diode is connected to the first input terminal of the amplifier, and the anode of the second diode is connected to the second input terminal of the amplifier. Using this device, when the branch under test is operating and the power transmitted on the branch under test is large, the amplitude of the secondary voltage output by the current transformer also increases. To prevent damage to the secondary-side components of the current transformer due to high voltage, a first diode and a second diode are configured between the two input terminals of the amplifier. The first diode clamps the voltage at the first input terminal of the amplifier, and the second diode clamps the voltage at the second input terminal of the amplifier, thereby protecting the secondary-side components of the current transformer.
[0012] In one possible design, the saturation flux density of the transformer core is less than a first preset threshold. With this design, the amplitude of the secondary voltage output by the transformer is mainly related to the operating frequency, the cross-sectional area of the core, the saturation flux density, and the turns ratio of the primary and secondary windings. Therefore, by configuring a core with low saturation flux density, the amplitude of the secondary voltage output by the transformer can be reduced, further decreasing the current amplitude on the secondary winding side of the transformer.
[0013] In one possible design, the cross-sectional area of the transformer core is less than a second preset threshold. With this design, the amplitude of the secondary voltage output by the transformer is mainly related to the operating frequency, the core cross-sectional area, the saturation magnetic flux density, and the turns ratio of the primary and secondary windings. Therefore, the voltage amplitude output on the secondary winding side can be reduced by decreasing the cross-sectional area of the transformer core, further reducing the current amplitude on the secondary winding side. Furthermore, the reduced core cross-sectional area also reduces the winding path of the transformer coil, further reducing the component cost and size of the reverse current detection circuit.
[0014] In one possible design, the number of turns in the secondary winding of the current transformer is less than a third preset threshold. With this design, the amplitude of the secondary voltage output by the current transformer is mainly related to the operating frequency, the cross-sectional area of the magnetic core, the saturation magnetic flux density, and the turns ratio of the primary and secondary windings. Therefore, by reducing the number of coils in the secondary winding, the transformation ratio between the primary and secondary voltages of the current transformer can be reduced, thereby reducing the voltage amplitude on the secondary winding side and ensuring the safe operation of the device.
[0015] In one possible design, the backflow detection circuit further includes the processing device, which is connected to the output of the amplifier and is used to determine that the device where the branch under test is located has a backflow fault when the branch under test is in an open state and the electrical parameter output by the amplifier is detected to be greater than a set value.
[0016] In one possible design, since the amplifier outputs an analog electrical signal that the aforementioned signal processing device cannot process directly, the reverse feed detection circuit further includes an analog-to-digital converter connected between the amplifier and the processing device. This analog-to-digital converter can convert the analog signal output by the amplifier into a digital signal that the processing device can process.
[0017] Secondly, embodiments of this application provide a power supply device that can connect to one or more electrical devices and fulfill their high-power consumption needs. The power supply device may include a UPS and a backflow detection circuit provided in the first aspect of this application and any possible design thereof.
[0018] The UPS input terminal is used to connect to the power supply, the switching power supply UPS is used to connect to the load, and the backflow detection circuit is connected to the UPS.
[0019] Furthermore, the technical effects of the second aspect and any of its possible designs can be found in the technical effects of different designs in the first aspect of the embodiments of this application, and will not be repeated here. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 A schematic diagram of the reverse flow detection circuit provided in this application embodiment. Figure 1 ;
[0022] Figure 2 A schematic diagram of the reverse flow detection circuit provided in this application embodiment. Figure 2 ;
[0023] Figure 3 A schematic diagram of the structure of an impedance module provided in this application embodiment. Figure 1 ;
[0024] Figure 4 A schematic diagram of the structure of an impedance module provided in this application embodiment. Figure 2 ;
[0025] Figure 5 This is a schematic diagram of a power supply device provided in an embodiment of this application. Detailed Implementation
[0026] The embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0027] The terminology used in the implementation section of this application is only for explaining specific embodiments of this application and is not intended to limit this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.
[0028] It should be noted that 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 data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.
[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The reverse current detection circuit provided in the embodiments of this application can be applied to a power supply device. The reverse current detection circuit can be connected to a power supply path of the power supply device, and determines whether a reverse current fault has occurred in the power supply device by detecting whether a reverse current appears on the connected path. The power supply device can be a device with a bypass branch and outputs AC power for power supply. For example, the power supply device can be an uninterruptible power supply (UPS). The reverse current detection circuit can be connected to the bypass branch in the UPS, and determines whether a reverse current fault has occurred in the power supply device by detecting the current amplitude on the bypass branch when the main circuit is powered.
[0030] See Figure 1 The diagram shown is a schematic representation of a reverse-current detection circuit provided in an embodiment of this application. Figure 1 As shown, the reverse flow detection circuit may include: a current transformer T, an impedance module, and an amplifier U.
[0031] The primary winding of the current transformer T can be connected to the branch under test, and the secondary winding of the current transformer T is connected to the impedance module. The current transformer T is used to detect the electrical parameters on the branch under test and output the detected values to the impedance module. The impedance module is connected to the processing device at the back end through the amplifier U. The impedance module is used to receive the electrical parameters output by the current transformer T, and output the detected electrical parameters to the amplifier U after current limiting. The amplifier U is used to amplify the electrical parameters output by the impedance module and output them to the processing device so that the processing device can perform reverse-current fault detection based on the electrical parameters output by the amplifier U.
[0032] It should be understood that, Figure 1 The backflow detection circuit structure shown is for illustrative purposes only. In practical applications, the backflow detection circuit can have more advanced features than... Figure 1 The additional components shown, such as the secondary winding of the current transformer T in the reverse current detection circuit, can also be connected to other processing devices for short circuit or leakage detection of the power supply device. Of course, the reverse current detection circuit can also include other functional devices, which will not be described in detail here.
[0033] In practical applications, the branch under test is the bypass branch of the power supply device. This bypass branch can serve as a power supply path between the power source and the load. When the power supply quality is good, the bypass branch can be controlled to conduct and the power source's energy can be used to directly supply power to the load. When the power supply quality is poor, the bypass branch can be controlled to disconnect and the main power supply circuit in the power supply device can be controlled to conduct. The components inside the main power supply circuit can convert and process the power source's energy before supplying power to the load, thereby meeting the load's power requirements. The reverse current detection circuit can detect the current value on the bypass branch when the power supply device is running using a current transformer T, and use the detected value to determine whether a reverse current fault has occurred in the power supply device.
[0034] The reverse current detection circuit provided in this application primarily detects reverse current faults by detecting whether a reverse current occurs in the bypass branch. Therefore, the current transformer T connected to the branch under test can be a current transformer. The primary winding of the current transformer is connected in series in the bypass branch of the power supply device, and the secondary winding of the current transformer is connected to the processing device through an impedance module and an amplifier U. When the power supply device is running and current flows in the bypass branch, current flows in the primary winding of the current transformer connected in series in the bypass branch. The current transformer can couple the current flowing in the primary winding to the secondary winding. The devices connected to the secondary winding process the above electrical signal and output it to the processing device. The processing device can use the above values to detect reverse current faults in the power supply device.
[0035] Specifically, the power supply methods of the power supply device mainly include main circuit power supply and bypass branch power supply. When the power supply device uses bypass branch power supply, the bypass branch is closed and the main power supply circuit is open. Since there is power supply current flowing through the bypass branch at this time, the processing device does not perform reverse feed fault identification on the received electrical signal. When the power supply device uses main power supply circuit power supply, the bypass branch is open and the main power supply circuit is closed. Under normal circumstances, the bypass branch is in an open state and no current flows. At this time, if the electrical parameters output by the amplifier are detected and the output electrical parameters are greater than the set value, it is determined that the current in the main power supply circuit is reverse fed to the bypass branch, and the power supply device has a reverse feed fault. The set value can be set according to the parameters of the internal components of the power supply device, and this application does not impose any restrictions here.
[0036] In one alternative approach, if the power supply device is equipped with a monitoring system, the backflow detection circuit provided in this embodiment can be applied to the monitoring system of the power supply device and connected to the processing device within the monitoring system. The processing device within the monitoring system then identifies the backflow fault. The monitoring system can also be connected to short-circuit detection circuits, leakage protection circuits, and other fault detection circuits, which will not be discussed in detail here.
[0037] In practical applications, the backflow detection circuit can be fixed to the monitoring system, which has a fixed interface. The power supply unit can be connected to the primary winding of the current transformer T through this fixed interface and cables. Alternatively, the backflow detection circuit can be fixed to the power supply unit, which also has a fixed interface. The monitoring system can be connected to the output of the amplifier through this fixed interface and cables. In another implementation, the backflow detection circuit can be designed to be flexible and detachable, allowing connection between the power supply unit, the monitoring system, and the backflow detection circuit. In this case, the backflow detection circuit can be considered a device independent of the monitoring system and the power supply unit.
[0038] Using the reverse current detection circuit provided in this application embodiment, the branch under test is the bypass branch of the power supply device. When the power supply device is running and current flows through the branch under test, current flows through the coil of the primary winding of the current transformer T and generates an electric field. This electric field is transmitted to the secondary winding of the current transformer T through the magnetic coupling of the magnetic core, generating a secondary current I2 and a secondary voltage V2. When the bypass branch is running, the bypass branch supplies power, and normal supply current flows through the coil of the primary winding of the current transformer T. Therefore, the secondary current I2 output by the secondary winding of the current transformer T during this period does not participate in the reverse current fault detection. When the bypass branch stops running and the main circuit is running, the main circuit supplies power. Under normal circumstances, no current flows through the bypass branch. If a reverse current is generated on the bypass branch, this reverse current can be transmitted to the secondary winding through the current transformer T. The processing device connected to the reverse current detection circuit can accurately identify whether a reverse current fault has occurred in the power supply device using the secondary current I2 output from the secondary winding side.
[0039] See also Figure 1 As shown, when the power supply unit starts working and the bypass branch supplies power, the secondary current I2 and secondary voltage V2 of the transformer T may damage the components due to the large current amplitude on the line during normal power supply. The impedance module composed of resistive devices can limit the secondary current I2 output by the secondary winding of the transformer T, thereby protecting the internal components of the reverse current detection circuit. Because the impedance module has the characteristic of limiting the current amplitude on the line, when the current amplitude generated on the secondary winding side exceeds the operating current requirements of the amplifier U and other connected devices, the current-limited signal from the impedance module can still ensure that the amplifier U and other devices can operate normally, thus improving the working stability of the reverse current detection circuit. Furthermore, since the cost of impedance devices is lower than the cost of adjusting the specifications of the devices connected to the secondary winding, the operating cost of the reverse current detection circuit can also be reduced.
[0040] In practical applications, the current-limiting effect of the impedance module can be adjusted by configuring an impedance device with an appropriate resistance value. If the reverse current detection circuit is considered an independent device, an adjustable resistor, such as a sliding resistor, can also be configured for the impedance module. When the reverse current detection circuit is connected to power supply devices of different power levels, the reverse current detection requirements of the power supply device can be met by adjusting the resistance value of the sliding resistor.
[0041] Based on the above description, the backflow fault identification of the power supply device is mainly confirmed by the processing device through the electrical signal detected by the backflow detection circuit. In practical applications, the backflow detection circuit can be connected to an external processing device, for example, the backflow detection circuit can be connected to an external monitoring system. The backflow detection circuit provided in this application embodiment may also include a processing device, which can be connected to the output terminal of amplifier U and use the electrical signal output by amplifier U to identify the backflow fault.
[0042] The current limiting process of the secondary side output electrical signal of the current transformer T will be described in detail below with reference to the embodiments.
[0043] In practical applications, reverse current detection circuits are often used in high-power power supply scenarios. When the power supply device is running, the amplitude of the secondary voltage V2 output by the current transformer T may be relatively large. To prevent damage to the devices on the secondary winding side due to high voltage, a clamping device is generally configured on the secondary winding side of the current transformer T. This clamping device can clamp the voltage amplitude output from the secondary winding to the downstream devices. The clamping device can be a diode or other devices with the above-mentioned functions. Taking the clamping device using a diode as an example, see [link to relevant documentation]. Figure 2 As shown, the reverse current detection circuit provided in this embodiment of the application, in addition to the above-mentioned devices, also includes a first diode D1 and a second diode D2. The anode of the first diode D1 is connected to the first input terminal of the amplifier U, and the cathode of the first diode D1 is connected to the second input terminal of the amplifier U. The cathode of the second diode D2 is connected to the first input terminal of the amplifier U, and the anode of the second diode D2 is connected to the second input terminal of the amplifier U.
[0044] See also Figure 2 As shown, when the secondary voltage V2 output by the transformer T is transmitted to the input terminal of the amplifier U through the impedance module, the first diode D1 or the second diode D2 meets the condition and turns on, thereby clamping the voltage at the input terminal of the amplifier U to the diode's turn-on voltage.
[0045] use Figure 1 In the reverse current detection circuit shown, when the power supply device starts working, the current flowing through the primary winding of the current transformer T is transmitted to the secondary winding of the current transformer T through magnetic core coupling. At this time, the secondary current I2 and the secondary voltage V2 output on the secondary winding of the current transformer T satisfy the following formula:
[0046] V² = 4.44 * N² * A * f * Bs (Formula 1)
[0047] I2=(V2-Vd) / Z (Formula 2)
[0048] Where N2 is the number of turns of the secondary winding of the current transformer T, A is the cross-sectional area of the magnetic core of the current transformer T, f is the operating frequency of the current transformer T, Bs is the saturation magnetic flux density of the magnetic core of the current transformer T, Vd is the clamping voltage of the diode on the secondary side of the current transformer T, and Z is the total impedance on the path between the diode and the secondary winding.
[0049] As can be seen from Formulas 1 and 2 above, the amplitude of the secondary current I2 output by the current transformer T is mainly determined by the secondary voltage V2 and the total impedance Z between the diode and the secondary resistor. Since an impedance module is additionally configured on the path between the diode and the secondary winding, the total impedance Z on the path between the diode and the secondary resistor is the sum of the internal resistance r of the secondary winding and the impedance of the impedance module. Compared with the existing technology that only has internal resistance, the total impedance of the secondary winding increases. Therefore, if the voltage amplitude of the voltage V2 output by the secondary winding remains unchanged, the amplitude of the current I2 on the secondary winding line of the current transformer T can be reduced, thereby avoiding damage to the devices on the secondary winding side due to overcurrent.
[0050] In practical applications, an impedance module may include at least one resistor, for example, see Figure 3 As shown, the first resistor R1 has its first end connected to the first interface of the secondary winding of the current transformer T, and its second end connected to the first input terminal of the amplifier U. The second interface of the secondary winding of the current transformer T is connected to the second input terminal of the amplifier U. With the first resistor R1 configured, the secondary current I2 of the current transformer T is I2 = (V2 - Vd) / (R1 + r). Due to the increased resistance of the path between the secondary winding and the clamping diode, the amplitude of the current I2 on the secondary side of the current transformer T can be reduced.
[0051] In one example, if the resistance value of a single resistor is insufficient, see [reference needed]. Figure 4 As shown, the impedance module also includes a second resistor R2 connected between the second interface of the secondary winding of the current transformer T and the second input terminal of the amplifier U. The first end of the second resistor R2 is connected to the second interface of the secondary winding of the current transformer T, and the second end of the second resistor R2 is connected to the second input terminal of the amplifier U. At this time, the secondary current I2 of the current transformer T is I2 = (V2 - Vd) / (R1 + R2 + r). Since the resistance of the path between the secondary winding and the clamping diode is further increased, the amplitude of the current I2 on the secondary side path of the current transformer T can be further reduced.
[0052] In this circuit, the first resistor R1 and the second resistor R2 can be resistors with fixed resistance values. The specifications of these resistors can be configured according to the current amplitude on the line when the bypass branch is normally powered and the models of the components in the reverse power supply detection circuit. Alternatively, the first resistor R1 and the second resistor R2 can be adjustable resistors, such as sliding rheostats, so that the resistance values of the first resistor R1 and the second resistor R2 can be adjusted to meet the reverse power supply fault detection requirements of different power supply devices.
[0053] It should be understood that the above description of the impedance module is only an example. In actual use, the impedance module can also adopt other circuit structures. For example, the first resistor R1 and the second resistor R2 in the impedance module can be composed of multiple resistors connected in series. The impedance module can also adopt other devices with current function commonly used in the industry. This application does not impose any restrictions here.
[0054] See Figures 1 to 4 As shown, the reverse current detection circuit provided in this application embodiment can add an impedance module to the original reverse current detection circuit architecture to increase the total impedance Z on the secondary winding side, thereby reducing the secondary current I2 on the secondary side of the transformer T. Based on the above formula two, it can be seen that the amplitude of the secondary current I2 is related to the secondary voltage V2. Therefore, the output current I2 of the secondary winding can also be reduced by decreasing the voltage amplitude of the secondary voltage V2. Combining with formula one, it can be seen that the output voltage V2 on the secondary side of the transformer T is mainly related to the number of turns N2 of the secondary winding, the cross-sectional area A of the magnetic core, and the saturation magnetic flux density Bs of the magnetic core. Therefore, the secondary current I2 of the transformer T can be reduced by adjusting the above parameters of the transformer T.
[0055] In one possible implementation, the saturation magnetic flux density of the transformer T's core is less than a first preset threshold. That is, by selecting a core material with low saturation magnetic flux density and high permeability, the output voltage V2 of the secondary winding is reduced, thereby further reducing the secondary current I2 on the secondary side of the transformer T. The first preset threshold can be set based on the parameters of the transformer T and the parameters of the impedance module's back-end connection device. For example, if the current allowed through the impedance module's back-end connection device is 3mA, the output voltage V2 of the secondary winding is 10.7V when the magnetic flux density of the transformer T's core is 10000T, and the total impedance Vd on the path between the diode and the secondary winding is 2KΩ, then the current amplitude received by the impedance module's back-end connection device is approximately 5mA. Therefore, the first preset threshold can be set to 5000T. Based on formulas one and two, it can be seen that at this time, the current amplitude received by the impedance module's back-end connection device is approximately 2.35mA, and the impedance module's back-end connection device can operate normally.
[0056] In one possible implementation, the cross-sectional area of the magnetic core of the current transformer T is smaller than a second preset threshold. It should be noted that reducing the cross-sectional area of the magnetic core also helps to reduce the winding wire diameter of the current transformer T. This, in addition to reducing the amplitude of the secondary current I2, also helps to reduce the size and cost of the current transformer T. The second preset threshold can be set according to the parameters of the current transformer T and the parameters of the impedance module's back-end connection devices. For example, if the current allowed through the impedance module's back-end connection devices is 3mA, the cross-sectional area of the magnetic core of the current transformer T is 2500mm². 2When the output voltage V2 of the secondary winding is 10.7V and the total impedance Vd on the path between the diode and the secondary winding is 2KΩ, the current amplitude received by the device connected to the back end of the impedance module is approximately 5mA. Therefore, the second preset threshold can be set to 1250mm. 2 Based on Formula 1 and Formula 2, it can be seen that at this time, the current amplitude received by the back-end connection device of the impedance module is about 2.35mA, and the back-end connection device of the impedance module can work normally.
[0057] In one possible implementation, the number of turns in the secondary winding of the current transformer T is less than a third preset threshold. It should be noted that reducing the number of turns in the secondary winding also helps to reduce the wire diameter of the secondary winding of the current transformer T. This, combined with reducing the amplitude of the secondary current I2, also helps to reduce the size and cost of the current transformer T. The third preset threshold can be set according to the parameters of the current transformer T and the parameters of the impedance module's back-end connection device. For example, if the current allowed through the impedance module's back-end connection device is 3mA, the output voltage V2 of the secondary winding of the current transformer T is 10.7V when the number of coils in the secondary winding is 100, and the total impedance Vd on the path between the diode and the secondary winding is 2KΩ, then the current amplitude received by the impedance module's back-end connection device is approximately 5mA. The third preset threshold can be set to 50. As shown in Formulas 1 and 2, the current amplitude received by the impedance module's back-end connection device is approximately 2.35mA, and the impedance module's back-end connection device can operate normally.
[0058] Based on the above description, this application also provides a power supply device that can be connected between a power source and a load. The power supply device can control the electrical connection between the power source and the load. When the output voltage of the power source differs from the supply voltage of the load, the power supply device can also convert the output voltage of the power source before outputting it to the load, thereby meeting the load's power requirements. See also... Figure 5 As shown, the power supply device may include a UPS and the aforementioned backflow detection circuit.
[0059] Specifically, the input terminal of the UPS is connected to the power supply, and the output terminal of the UPS is connected to the load; the backflow detection circuit is connected to the bypass branch inside the UPS. The structure of the backflow detection circuit can be found in the foregoing description, and will not be repeated here.
[0060] In one possible implementation, the UPS may also include an energy storage battery pack or an external energy storage battery pack. When the external AC power supply to the UPS is working normally, the UPS can use the AC power to supply power to the downstream loads and charge the energy storage battery pack. When the external AC power supply to the UPS fails, the UPS can use the energy stored in the energy storage battery pack to supply power to the downstream loads, thereby improving the power supply stability of the UPS.
[0061] In practical applications, the backflow detection circuit and UPS can be integrated into a single cabinet. The cabinet is equipped with power interfaces and load interfaces. External power supplies can be connected to the power supply unit via the power interfaces, and loads can be connected to the power supply unit via the load interfaces to obtain power. The cabinet may also include other interfaces, allowing external devices to connect to the backflow detection circuit and UPS. For example, the cabinet may also include interfaces for leakage current detection and interfaces for connecting to monitoring systems.
[0062] In some implementations, when the backflow detection circuit is integrated with the UPS in a single cabinet, the backflow detection circuit and other components in the power supply unit can be located on the same printed circuit board (PCB) or on different PCBs.
[0063] It should be noted that, Figure 5 The power supply device shown is a UPS, which is only an example. In actual applications, the power supply device may include other switching power supply structures with bypass branches and output AC power for power supply. This application does not make specific limitations here.
[0064] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.
Claims
1. A reverse-current detection circuit, characterized in that, include: Current transformers, impedance modules, and amplifiers; The primary winding of the current transformer is used to connect to the branch under test, the secondary winding of the current transformer is connected to the impedance module, and the current transformer is used to detect the electrical parameters on the branch under test and output the detected values to the impedance module. The impedance module is connected to the processing device through the amplifier. The impedance module is used to receive the electrical parameters output by the current transformer, and outputs the detected electrical parameters to the amplifier after current limiting. The amplifier is used to amplify the electrical parameters output by the impedance module and then output them to the processing device.
2. The circuit according to claim 1, characterized in that, The impedance module includes a first resistor; The first end of the first resistor is connected to the first interface of the secondary winding of the current transformer, and the second end of the first resistor is connected to the first input terminal of the amplifier. The second interface of the secondary winding of the current transformer is connected to the second input terminal of the amplifier.
3. The circuit according to claim 2, characterized in that, The impedance module also includes a second resistor connected between the second interface of the secondary winding of the current transformer and the second input terminal of the amplifier.
4. The circuit according to any one of claims 1 to 3, characterized in that, The reverse flow detection circuit also includes a first diode and a second diode; The anode of the first diode is connected to the first input terminal of the amplifier, and the cathode of the first diode is connected to the second input terminal of the amplifier. The cathode of the second diode is connected to the first input terminal of the amplifier, and the anode of the second diode is connected to the second input terminal of the amplifier.
5. The circuit according to any one of claims 1 to 3, characterized in that, The saturation magnetic flux density of the transformer core is less than a first preset threshold.
6. The circuit according to any one of claims 1 to 3, characterized in that, The cross-sectional area of the magnetic core of the current transformer is less than the second preset threshold.
7. The circuit according to any one of claims 1 to 3, characterized in that, The number of turns in the secondary winding of the current transformer is less than a third preset threshold.
8. The circuit according to any one of claims 1 to 3, characterized in that, The backflow detection circuit also includes the processing device, which is connected to the output terminal of the amplifier. The processing device is used to determine that the equipment where the branch under test is located has a backflow fault when the branch under test is in an open state and the electrical parameter output by the amplifier is greater than a set value.
9. The circuit according to claim 8, characterized in that, The backflow detection circuit also includes an analog-to-digital converter connected between the amplifier and the processing device.
10. A power supply device, characterized in that, include: UPS and the backflow detection circuit as described in any one of claims 1 to 9; The input terminal of the UPS is used to connect to the power supply, and the output terminal of the UPS is used to connect to the load. The backflow detection circuit is connected to the UPS.