Alternating current and direct current isolation and automatic switching type power supply circuit

Abstract

The utility model discloses an AC / DC isolation and automatic switching type power supply circuit. The circuit comprises a DC input end used for receiving a DC power supply; an AC input for receiving an AC power supply; the fuse is respectively connected to the direct current input end and the alternating current input end and is used for providing over-current protection; the filters are respectively connected to the output ends of the fuses and are used for filtering electromagnetic interference; and the surge protection devices are respectively connected to the output ends of the filter and are used for attenuating input surge and protecting rear-end devices. According to the AC / DC isolation and automatic switching type power supply circuit provided by the utility model, automatic switching, isolation and stable power supply of an AC / DC power supply are realized through the fuse, the filter, the surge protection device and the rectifier bridge, and the circuit has the advantages of simple operation, low cost and high reliability. The circuit is suitable for emergency lamps, lighting circuits and other equipment needing uninterrupted power supply, and the service life of the equipment and the battery is effectively prolonged.

Description

Technical Field

[0001] The utility model relates to a power supply circuit, in particular to an AC-DC isolation and automatic switching power supply circuit. Background Art

[0002] In current electrical equipment applications, many devices need to use AC and DC power sources simultaneously. AC power sources (such as mains power) are usually stable and reliable, but cannot provide continuous power supply during power outages or abnormal situations. While DC power sources (such as battery packs) can provide backup power when the AC power source fails, their power supply time is limited and their service life is finite.

[0003] Traditional power supply circuits often require manual switching between AC and DC power sources, which is not only complex to operate, but also may cause power outages during the switching process, affecting the normal operation of the equipment. To solve this problem, it is particularly important to design a power supply circuit that can automatically switch between AC and DC power sources and isolate them from each other.

[0004] In the prior art, the automatic switching between AC and DC power sources is usually achieved through complex control circuits or multiple power management chips, but these solutions are often costly and have limited reliability, making it difficult to meet the requirements of certain application scenarios. Therefore, there is an urgent need for an AC-DC isolation and automatic switching power supply circuit with a simple structure, low cost and high reliability to meet the market demand. Summary of the Utility Model

[0005] To solve the above problems, the utility model provides an AC-DC isolation and automatic switching power supply circuit, aiming to solve the above problems. Through a simple circuit design, the automatic switching and isolation of AC and DC power sources are realized, ensuring the stable operation of the equipment under various power supply conditions.

[0006] The utility model is realized through the following technical solutions: an AC-DC isolation and automatic switching power supply circuit, comprising:

[0007] A DC input terminal for receiving a DC power source;

[0008] An AC input terminal for receiving an AC power source;

[0009] Fuses respectively connected to the DC input terminal and the AC input terminal, for providing overcurrent protection;

[0010] Filters respectively connected to the fuse output terminals, for filtering out electromagnetic interference;

[0011] Surge protection devices respectively connected to the filter output terminals, for attenuating input surges and protecting the backend devices;

[0012] A rectifier bridge connected to the output end of the surge protection device, which is used to convert alternating current into direct current and provide isolation between AC and DC inputs;

[0013] A filter capacitor connected to the output end of the rectifier bridge, which is used to smooth the rectified DC output;

[0014] An output end used to provide an isolated and automatically switched DC output.

[0015] As a preferred technical solution, the DC input end is connected to a battery pack for DC power supply.

[0016] As a preferred technical solution, the AC input end is connected to the mains for AC power supply.

[0017] As a preferred technical solution, the filter is a common mode inductor.

[0018] As a preferred technical solution, the surge protection device is a varistor.

[0019] As a preferred technical solution, the filter capacitor is an electrolytic capacitor.

[0020] As a preferred technical solution, when the AC power supply is normally powered, the voltage output after rectification and filtering of the AC input is higher than the DC input voltage. At this time, the rectifier bridge conducts, and the DC power supply does not supply power;

[0021] When the AC power supply is abnormal or power failure occurs, the output voltage is lower than or equal to the DC input voltage. At this time, the rectifier bridge conducts, and the DC power supply supplies power, thus realizing the automatic switching of AC and DC power supplies.

[0022] The beneficial effects of the present utility model are: when the AC power supply is normally powered, the system automatically selects AC power supply, and the DC power supply does not supply power; when the AC power supply is abnormal or power failure occurs, the system automatically switches to DC power supply, realizing the automatic switching of AC and DC power supplies, without external control signals, simplifying the operation and control;

[0023] By using a fuse to provide overcurrent protection, ensuring the safe operation of the circuit under abnormal current conditions; the filter can effectively filter out electromagnetic interference and improve the power supply quality; the surge protection device can attenuate the input surge, protect the backend devices and equipment, and enhance the stability and reliability of the circuit;

[0024] The rectifier bridge enables effective isolation of the AC input and the DC input in the circuit, avoiding mutual interference between the AC and DC power supplies, and ensuring the stability and safety of the power supply;

[0025] This circuit design is simple, with low cost, and is suitable for occasions where AC and DC power supplies coexist and need to be automatically switched, such as emergency lights, lighting circuits, and other devices to be powered, providing a stable and reliable power supply solution for these devices;

[0026] Through the automatic switching function, battery power supply can be avoided when the mains power supply is normal, thus prolonging the service life of the battery, reducing the maintenance cost and replacement frequency of the device, and improving the overall service life of the device. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is the circuit schematic diagram of the present invention. Detailed Embodiments

[0029] All features disclosed in this specification, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

[0030] Any feature disclosed in this specification (including any additional claims, abstract, and drawings), unless specifically stated, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically stated, each feature is just an example of a series of equivalent or similar features.

[0031] As Figure 1 shown, an AC-DC isolation and automatic switching power supply circuit of the present invention includes a DC input terminal for receiving a DC power supply;

[0032] an AC input terminal for receiving an AC power supply;

[0033] fuses respectively connected to the DC input terminal and the AC input terminal, for providing overcurrent protection;

[0034] filters respectively connected to the fuse output terminals, for filtering out electromagnetic interference;

[0035] surge protection devices respectively connected to the filter output terminals, for attenuating input surges and protecting the rear-end devices;

[0036] a rectifier bridge respectively connected to the surge protection device output terminals, for converting alternating current into direct current and providing AC-DC input isolation;

[0037] filter capacitors connected to the rectifier bridge output terminals, for smoothing the rectified DC output;

[0038] An output terminal for providing isolated and automatically switched DC output.

[0039] Among them, the DC input terminal is connected to the battery pack for DC power supply, the AC input terminal is connected to the mains for AC power supply, the filter is a common-mode inductor, and the surge protection device is a varistor.

[0040] The filter capacitor is an electrolytic capacitor. When the AC power supply is normally powered, the voltage output after rectification and filtering of the AC input is higher than the DC input voltage. At this time, the rectifier bridge conducts, and the DC power supply does not supply power.

[0041] When the AC power supply is abnormal or powered off, the output voltage is lower than or equal to the DC input voltage. At this time, the rectifier bridge conducts, and the DC power supply supplies power, thus realizing the automatic switching of AC and DC power supplies.

[0042] The working process is as follows:

[0043] When the DC input terminal J1 and the AC input terminal J2 are respectively connected to the DC power supply and the AC power supply, first, the fuses F1 and F2 are passed to provide overcurrent protection to prevent abnormal current from damaging the circuit. Then, the current flows through the filters LF1 and LF2 to filter out electromagnetic interference and improve the power quality. Next, the current enters the surge protection devices VR1 and VR2 to attenuate the input surge and protect the subsequent circuits and equipment.

[0044] After passing through the surge protection device VR2, the AC power supply enters the rectifier bridge BD2 and is converted into direct current. At this time, the filter capacitor EC1 smooths the rectified direct current and outputs a stable DC voltage. When the AC power supply is normally powered, the rectified voltage is higher than the DC power supply voltage, the rectifier bridge BD2 conducts, and the rectifier bridge BD1 is reversely cut off, and the DC power supply does not supply power.

[0045] When the AC power supply is abnormal or powered off, the voltage at the AC input terminal J2 drops to be lower than or equal to the voltage at the DC input terminal J1. At this time, the rectifier bridge BD1 conducts, and the rectifier bridge BD2 is reversely cut off, and the DC power supply is connected to supply power to ensure the continuous operation of the equipment. Through this design, the automatic switching of AC and DC power supplies is realized, without the need for an external control signal, simplifying the operation and control process.

[0046] This circuit can use AC power supply when the mains is normal, and automatically switch to battery power supply when the mains is powered off, thus realizing the continuity and stability of power supply. Through effective power management, the utility model not only improves the power supply reliability of the equipment, but also extends the service life of the battery, reduces the maintenance cost and replacement frequency of the equipment.

[0047] Specifically, in this embodiment, the DC input terminal J1 is connected to a 12V battery pack as the DC power input. The AC input terminal J2 is connected to the 220V mains power as the AC power input. The fuses F1 and F2 are respectively connected behind the DC input terminal and the AC input terminal to protect the circuit in case of overcurrent.

[0048] The DC input terminal J1 is connected to the filter LF1 through the fuse F1. This filter is used to filter out the electromagnetic interference signals in the direct current. The AC input terminal J2 is connected to the filter LF2 through the fuse F2. This filter is used to filter out the electromagnetic interference signals in the alternating current.

[0049] The filtered direct current enters the rectifier bridge BD1 through the surge protection device VR1. The surge protection device VR1 is used to absorb the surge voltage in the DC power supply and protect the subsequent circuit. The filtered alternating current enters the rectifier bridge BD2 through the surge protection device VR2. The surge protection device VR2 is used to absorb the surge voltage in the AC power supply and protect the subsequent circuit.

[0050] The rectifier bridge BD1 directly delivers the direct current to the output terminal. The rectifier bridge BD2 rectifies the alternating current into direct current, and then outputs it to the output terminal after filtering through the filter capacitor EC1. When the mains power is normally supplied, the rectified DC voltage is higher than the DC voltage of the battery pack. The rectifier bridge BD1 is reverse cut-off, and the rectifier bridge BD2 is turned on. The output terminal is powered by the voltage rectified from the AC power supply.

[0051] When the mains power is abnormal or there is a power outage, the rectified voltage is lower than or equal to the DC voltage of the battery pack. The rectifier bridge BD2 is reverse cut-off, and the rectifier bridge BD1 is turned on. The direct current of the battery pack is supplied through the rectifier bridge BD1, ensuring continuous power supply to the output terminal.

[0052] For example, assume the voltage of the battery pack is 12V. When the mains power is normally supplied, the voltage after rectification and filtering is about 310V (220V AC to 310V DC). At this time, the rectifier bridge BD1 is reverse cut-off, the battery pack does not supply power, and the rectifier bridge BD2 is turned on. The supply voltage of the output terminal is 310V. When the mains power is out or abnormal, the output voltage drops to 12V or lower. At this time, the rectifier bridge BD2 is reverse cut-off, the rectifier bridge BD1 is turned on, and the 12V direct current of the battery pack supplies power to ensure the normal operation of the device.

[0053] As described above, it is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any change or replacement that can be thought of without creative work should be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope defined by the claims.

Claims

1. An AC / DC isolation and automatic switching power supply circuit, characterized in that: include: A DC input terminal for receiving a DC power source; an AC input terminal for receiving an AC power source; Fuses connected to the DC input terminal and the AC input terminal respectively for providing overcurrent protection; Filters connected to the output terminals of the fuses are used to filter out electromagnetic interference; Surge protection devices respectively connected to the output end of the filter are used to attenuate input surges and protect the back-end devices; Rectifier bridges respectively connected to the output end of the surge protection device are used to convert AC power into DC power and provide AC / DC input isolation; The filter capacitor connected to the output of the rectifier bridge is used to smooth the rectified DC output; Output terminals for providing isolated and automatically switched DC outputs.

2. The AC / DC isolated and automatically switched power supply circuit according to claim 1, characterized in that: The DC input terminal is connected to a battery pack for DC power supply.

3. The AC / DC isolation and automatic switching power supply circuit according to claim 1, characterized in that: The AC input terminal is connected to the mains for AC power supply.

4. The AC / DC isolation and automatic switching power supply circuit according to claim 1, characterized in that: The filter is a common mode inductor.

5. The AC / DC isolation and automatic switching power supply circuit according to claim 1, characterized in that: The surge protection device is a varistor.

6. The AC / DC isolated and automatically switched power supply circuit according to claim 1, characterized in that: The filter capacitor is an electrolytic capacitor.

7. The AC / DC isolated and automatically switched power supply circuit according to claim 1, characterized in that: When the AC power supply is normal, the output voltage of the AC input after rectification and filtering is higher than the DC input voltage. At this time, the rectifier bridge is turned on and the DC power supply does not supply power; When the AC power supply is abnormal or blackout, the output voltage is lower than or equal to the DC input voltage. At this time, the rectifier bridge is turned on and the DC power supply is supplied, thereby realizing automatic switching of AC and DC power supply.

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