A power supply switching and charge-discharge management circuit for a capacitor-powered device

Abstract

The present invention discloses a power supply switching and charge-discharge management circuit for a capacitor-powered device, which aims to solve the problem of using a backup power supply to supply power when the external power supply fails, and charging the backup power supply when the external power supply is restored. The circuit includes a first power supply path, a second power supply path, a first control circuit, a second control circuit and a charging circuit. Among them, the first power supply path and the second power supply path are respectively connected to the external power supply and the backup power supply, and are connected to the output end through a switch tube and an anti-reverse device. The first control circuit and the second control circuit control the conduction state of the switch tube according to the output terminal voltage and the external power supply voltage to achieve switching between the external power supply and the backup power supply. The charging circuit charges the backup power supply when the external power supply is normal. The present invention adopts components such as Schottky diodes and P-channel MOSFETs to achieve power supply switching and charge-discharge management, and is suitable for occasions with high requirements for power supply reliability.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a power supply switching and charge-discharge management circuit for a capacitor-powered device. Background Art

[0002] With the development and application of modern power systems, many power devices need to operate stably under various power supply conditions. Especially in the feeder terminal devices of power systems, the problems of equipment shutdown or data loss caused by the loss of external power supply are becoming increasingly prominent. To ensure that these devices can continue to work when the external power supply is lost, a backup power supply (such as a storage battery) is usually configured as an emergency power supply source. However, there are some problems with existing backup power supply management circuits.

[0003] In the process of power supply switching of traditional power supply switching circuits when the external power supply is lost and restored, the switching is not smooth enough, which is likely to cause instantaneous power-off or power supply interruption of the device, affecting the normal operation of the device. When the existing charge management circuit charges the backup power supply, it is difficult to adjust the charging current according to actual needs, resulting in low charging efficiency, long charging time, and even possibly affecting the life of the backup power supply.

[0004] In addition, many backup power supply management circuits lack an effective current reverse protection mechanism, which is easily damaged by reverse current, reducing the reliability and stability of the circuit. The switching devices and control circuits used in traditional circuits have high power consumption problems, resulting in a low overall energy efficiency ratio, which does not meet the requirements of energy conservation and environmental protection for modern power devices. Summary of the Invention

[0005] The present invention proposes a power supply switching and charge-discharge management circuit for a capacitor-powered device, aiming to solve the problem of providing power to a load through a backup power supply when the external power supply is lost and charging the backup power supply when the external power supply is restored.

[0006] A power supply switching and charge-discharge management circuit for a capacitor-powered device proposed by the present invention includes a first power supply path, a second power supply path, a first control circuit, a second control circuit, and a charging circuit;

[0007] The first power supply path includes an external power supply, a first anti-reverse device, a switching tube, and an output node connected in sequence;

[0008] The control end of the switching tube is connected to the first control circuit and the second control circuit;

[0009] The second power supply path includes a backup power supply, a second anti-reverse device, the switching tube, and the output node connected in sequence;

[0010] The charging circuit has its input end connected to the external power supply and its output end connected to the backup power supply;

[0011] The output node is connected to the load.

[0012] Further, the first anti-reverse device and the second anti-reverse device are anti-reverse Schottky diodes.

[0013] Specifically, the switching transistor is a P-channel enhancement-mode MOSFET.

[0014] Further, the first control circuit includes a first resistor, a second resistor, a turn-off switch, and a start switch;

[0015] The first resistor and the turn-off switch connected in parallel have one end connected to the first power supply path and the second power supply path, and the other end connected to one end of the second resistor;

[0016] The other end of the second resistor is connected in series with the start switch, and the start switch is grounded.

[0017] The first control circuit further includes a first control triode and a third resistor. The collector of the first control triode is connected to the control end of the switching transistor through the second resistor, the emitter is grounded, and the base is connected to the output node through the third resistor.

[0018] Specifically, the second control circuit includes a second control triode and a fourth resistor. The collector of the second control triode is connected to the control end of the switching transistor through the first control circuit, the emitter is grounded, and the base is connected to the external power supply through the fourth resistor.

[0019] Further, the charging circuit includes a linear voltage regulator and a current regulating element; the input end of the linear voltage regulator is connected to the external power supply, and the output end is connected to the backup power supply through the current regulating element.

[0020] The current regulating element is a fifth resistor. The output voltage of the linear voltage regulator and the resistance value of the fifth resistor jointly determine the charging current, and the maximum value of the charging current is the fixed voltage difference of the linear voltage regulator divided by the resistance value of the fifth resistor.

[0021] Specifically, the backup power supply is a storage battery.

[0022] Further, the load is a feeder terminal device.

[0023] The beneficial effects of the present invention are as follows:

[0024] When the external power supply loses power, the circuit can automatically switch to the backup power supply to ensure that the load can still operate normally during a power outage, avoiding equipment downtime or data loss caused by power outages and improving the reliability and continuity of the system.

[0025] When the external power supply resumes power supply, the charging circuit can automatically start to charge the backup power supply. By the cooperation of a linear voltage regulator and a current regulating resistor, the appropriate charging current can be set according to actual needs to ensure that the backup power supply has sufficient power during the next power outage, providing guarantee for continuous power supply.

[0026] The circuit selects Schottky diodes as anti-reverse devices. Schottky diodes have the characteristics of low conduction voltage drop and fast switching speed, improving the response speed of the circuit while ensuring low power consumption. In addition, Schottky diodes also have good anti-reverse current ability, preventing reverse current from damaging the circuit and components and improving the stability and reliability of the circuit.

[0027] Through the design of the first control circuit and the second control circuit, the control of the MOSFET switch tube is realized. Under different power supply states, the circuit can automatically adjust the conduction state of the switch tube to achieve power supply switching, ensuring continuous power supply to the load.

[0028] The circuit selects P-channel enhancement-mode MOSFETs as switch tubes. P-channel enhancement-mode MOSFETs have the advantages of low on-resistance, fast switching speed, and low drive power consumption. Compared with other types of switching devices, P-channel enhancement-mode MOSFETs reduce power loss while maintaining the energy transfer efficiency, improving the energy efficiency of the circuit.

[0029] The circuit provides a power supply switching and charge-discharge management solution. By optimizing the circuit design and component selection, it takes into account the continuity, reliability, and energy efficiency of power supply, is applicable to occasions with high requirements for power supply quality, and has certain practical value and application prospects. Brief Description of the Drawings

[0030] Figure 1 is the principle block diagram of the power supply switching and charge-discharge management circuit of the capacitor-powered device in an embodiment of the present invention;

[0031] Figure 2 is the circuit diagram of the power supply switching and charge-discharge management of the capacitor-powered device in an embodiment of the present invention. Detailed Embodiments

[0032] The technical solution of the present invention will be elaborated in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the described embodiments are only used to explain the technical principle of the present invention, rather than limiting the scope of its patent protection. Those skilled in the art should understand that various transformations, modifications or equivalent replacements can be made to these embodiments without departing from the spirit and scope of the present invention. These transformations, modifications or equivalent replacements should all be regarded as falling within the protection scope defined by the claims of the present invention. The specific implementation manners of the present invention have been described by way of examples. However, it should be understood that the described embodiments are only a part of the implementation manners of the present invention, rather than all the implementation manners. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0033] Refer to Figure 1 , which is a simplified principle block diagram of the power supply switching and charge-discharge management circuit of a capacitive power-taking device in an embodiment of the present invention. The figure includes an external power supply, a backup power supply, a switching tube, an output node, a load, a charging circuit, a first control circuit, and a second control circuit. The external power supply is connected to the switching tube through a first power supply path, the backup power supply is connected to the switching tube through a second power supply path, the output of the switching tube is connected to the output node, and the output node supplies power to the load.

[0034] The charging circuit is connected between the external power supply and the backup power supply. When the external power supply is supplying power normally, the charging circuit charges the backup power supply.

[0035] The first control circuit controls the conduction state of the switching tube according to the voltage state of the output node to realize the power supply switching of the backup power supply.

[0036] The second control circuit controls the conduction state of the switching tube according to the voltage state of the external power supply to realize the power supply switching of the external power supply.

[0037] The cooperation of the first control circuit and the second control circuit realizes the automatic switching between the external power supply and the backup power supply, ensuring the continuous power supply of the load.

[0038] It should be noted that this principle block diagram is drawn in a simplified manner to illustrate the basic principle and main components of the present invention. The actual circuit includes more components and connection details to realize the functions of each part.

[0039] Refer to Figure 2, this embodiment provides a power supply switching and charge-discharge management circuit for a capacitive power-taking device, including a first power supply path, a second power supply path, a first control circuit, a second control circuit, and a charging circuit. Among them, the first power supply path includes an external power supply PWR, a first reverse-blocking device D1, a switching transistor Q1, and an output node VCC connected in sequence; the second power supply path includes a backup power supply BAT, a second reverse-blocking device D2, the switching transistor Q1, and the output node VCC connected in sequence; the charging circuit includes a voltage regulator U1 and a current regulating element R5, whose input terminal is connected to the external power supply PWR and the output terminal is connected to the backup power supply BAT. The output terminal VCC is connected to a load, that is, a feeder terminal device.

[0040] In this embodiment, both the first reverse-blocking device D1 and the second reverse-blocking device D2 are Schottky diodes. Schottky diodes have the advantages of small conduction voltage drop and fast switching speed, and are particularly suitable for such application scenarios. Of course, the first reverse-blocking device D1 and the second reverse-blocking device D2 can also be other types of unidirectional conduction elements, such as ordinary diodes, fast-recovery diodes, etc.

[0041] The switching transistor Q1 is preferably a P-channel enhancement-mode MOSFET. The P-channel enhancement-mode MOSFET has the advantages of small on-resistance, fast switching speed, and low drive power consumption. In other embodiments, the switching transistor Q1 can also be other types of electronic switching devices, such as PNP bipolar junction transistors, PNP insulated gate bipolar transistors (IGBTs), etc.

[0042] Specifically, the first control circuit includes a first resistor R1, a second resistor R2, a turn-off switch S2, a start switch S1, a first control triode Q2, and a third resistor R3. The turn-off switch S2 and the start switch S1 can be ordinary mechanical push-button switches or electronic switches, such as transistor switch circuits. The first control triode Q2 is preferably an NPN-type triode, and can also be a PNP-type triode in other embodiments, in which case the circuit needs to be adjusted appropriately. The first resistor R1 and the turn-off switch S2 are connected in parallel, one end of which is connected to the first power supply path and the second power supply path, and the other end is connected to one end of the second resistor R2; the other end of the second resistor R2 is connected in series with the start switch S1, and the start switch S1 is grounded. The collector of the first control triode Q2 is connected to the gate of the switching transistor Q1 through the second resistor R2, the emitter is grounded, and the base is connected to the output node VCC through the third resistor R3.

[0043] The second control circuit includes a second control triode Q3 and a fourth resistor R4. The model and parameters of the second control triode Q3 may be the same as or different from those of the first control triode Q2, depending on the actual application requirements. The collector of the second control triode Q3 is connected to the gate of the switching transistor Q1 through the first control circuit, the emitter is grounded, and the base is connected to the external power supply PWR through the fourth resistor R4.

[0044] In this embodiment, the voltage regulator U1 is a linear voltage regulator, which has the advantages of low noise, small ripple, and large current, and is particularly suitable for occasions with high requirements for power supply quality. In other embodiments, the voltage regulator U1 may also be a switching voltage regulator. The current regulating element R5 is preferably a resistor, or may also be other types of shunt elements, such as a current detection amplifier.

[0045] The backup power supply BAT is preferably a lithium-ion battery, which has the advantages of high energy density, long cycle life, and small self-discharge. In other embodiments, the backup power supply BAT may also be other types of secondary batteries, such as nickel-metal hydride batteries, lead-acid batteries, etc., or other energy storage elements such as supercapacitors.

[0046] In the case of power failure of the external power supply PWR, its voltage is 0V. At this time, the backup battery power supply BAT provides power for the load through the second anti-reverse Schottky diode D2. When the start switch S1 is closed, the battery voltage is divided by the first resistor R1 and the second resistor R2, generating a negative voltage between the gate and source of the P-channel MOSFET switch Q1. By selecting appropriate values of R1 and R2, the negative voltage exceeds the start voltage of Q1, and Q1 conducts. Its on-resistance is about 20mΩ, and the output node VCC is powered on, and the feeder terminal device operates normally. After the VCC is powered on, the first control triode Q2 is driven through the third resistor R3. By selecting an appropriate value of R3, the base voltage of Q2 is greater than 0.7V, and Q2 operates in saturation, and its collector and emitter are conducting, approaching a short circuit. At this time, even if the start switch S1 is disconnected, the feeder terminal device can still remain operating. When the shutdown switch S2 is closed, the voltage between the gate and source of the P-channel MOSFET switch Q1 is 0, which does not reach the start voltage of Q1, and Q1 does not conduct, and the output node VCC loses power, and the feeder terminal device stops operating.

[0047] When the external power supply PWR is supplying power normally, its voltage provides power for the load through the first reverse protection Schottky diode D1. At the same time, the external power supply PWR drives the second control triode Q3 through the fourth resistor R4. By selecting an appropriate resistance value of R4, the base voltage of Q3 is made greater than 0.7V, and Q3 operates in saturation, with its collector and emitter conducting. The voltage of the external power supply PWR is divided by the first resistor R1 and the second resistor R2 to generate a negative voltage between the gate and source of the P-channel MOSFET switch Q1. Q1 conducts, and the output node VCC is powered on, and the feeder terminal device operates normally.

[0048] Under normal operating conditions, the external power supply PWR charges the backup battery power supply BAT through the charging circuit. The voltage difference between the output terminal OUT and the adjustment terminal ADJ of the linear voltage regulator U1 is fixed at 1.25V, and the charging current can be changed by adjusting the resistance value of the current adjustment resistor R5. The maximum charging current is 1.25 / R5.

[0049] In this embodiment, through the automatic switching between the first power supply path and the second power supply path, power is supplied to the load using the backup power supply when the external power supply loses power, ensuring uninterrupted operation of the load. At the same time, when the external power supply is supplying power normally, the backup power supply is charged through the charging circuit, keeping the backup power supply always fully charged and preparing for power supply when the external power supply loses power next time. In addition, the circuit structure of the present invention is simple, with low cost and high reliability, and is particularly suitable for occasions with high requirements for power supply continuity.

[0050] The present invention has been described in detail through the above specific embodiments. However, it should be understood that the above content is only illustrative and not used to limit the scope of the present invention. Those of ordinary skill in the art can make various modifications and variations to the present invention according to the specific application scenarios and actual needs without departing from the spirit and scope of the present invention, and these modifications and variations are all within the protection scope of the present invention.

Claims

1. A power supply switching and charge-discharge management circuit for capacitor power supply equipment, characterized in that: It includes a first power supply path, a second power supply path, a first control circuit, a second control circuit and a charging circuit; The first power supply path includes a first anti-reverse device, a switch tube and an output node connected in sequence, and the first anti-reverse device is also connected to an external power supply; The control end of the switch tube is connected to the first control circuit and the second control circuit; The second power supply path includes a backup power supply, a second anti-reverse device, the switch tube and the output node connected in sequence; Wherein, the first control circuit includes a first resistor, a second resistor, a shutoff switch and a start switch; After the first resistor and the shutdown switch are connected in parallel, one end of the first resistor is connected to the first power supply path and the second power supply path, and the other end is connected to one end of the second resistor and the control end of the switch tube; the other end of the second resistor is connected in series with the start switch, and the start switch is grounded; The first control circuit also includes a first control transistor and a third resistor. The collector of the first control transistor is connected to the control end of the switch tube through the second resistor. The emitter is grounded, and the base is connected to the output node through the third resistor; The second control circuit comprises a second control transistor and a fourth resistor, wherein the collector of the second control transistor is connected to the control end of the switch tube through the second resistor in the first control circuit, the emitter is grounded, and the base is connected to the external power supply through the fourth resistor; The input end of the charging circuit is connected to the external power supply, and the output end is connected to the backup power supply; The output node is connected to a load.

2. The circuit according to claim 1, characterized in that The charging circuit includes a linear regulator and a current regulating element; the input end of the linear regulator is connected to the external power supply, and the output end is connected to the backup power supply through the current regulating element.

3. The circuit according to claim 2, characterized in that The current regulating element is a fifth resistor, the output voltage of the linear regulator and the resistance value of the fifth resistor jointly determine the charging current, and the maximum value of the charging current is the fixed voltage difference of the linear regulator divided by the resistance value of the fifth resistor.

4. The circuit according to claim 1, characterized in that The switch tube is a P-channel enhancement type MOSFET.

5. The circuit according to claim 1, characterized in that The backup power source is a battery.

6. The circuit according to claim 1, characterized in that The load is a feeder terminal device.

7. The circuit according to claim 1, characterized in that The first anti-reverse device and the second anti-reverse device are anti-reverse Schottky diodes.

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