A charger capable of automatic power-off

Abstract

This utility model discloses a charger with automatic power-off capability, belonging to the field of charging technology for low-voltage electrical load equipment. By placing a double-pole relay between the power supply end and the input end of the first voltage conversion module, and detecting the current of the output interface in real time, if the output current is less than the output threshold for a period of time, it is determined that the battery is fully charged. The central processing unit generates a power-off signal and controls the double-pole relay to disconnect through the relay drive module. By disconnecting the power from the charger input end, the power-off is more thorough, ensuring that the charger does not generate any power consumption after charging is completed, thereby reducing waste. Furthermore, by detecting multiple current sampling points within a certain period of time, the values ​​are more accurate and the results are more precise and reliable, avoiding the possibility of false triggering.

Description

Technical Field

[0001] This utility model relates to the field of charging technology for low-voltage electrical load equipment, specifically to a charger that can automatically disconnect power. Background Technology

[0002] Modern charging adapters for electronic devices typically consist of a low-voltage power supply circuit comprised of a switching power supply and feedback loops for constant voltage and constant current. Essentially, its output voltage is constant, while the output current varies according to the load. For example, a flyback switching power supply uses a high-frequency pulse isolation transformer to isolate the input and output circuits. It has advantages such as fewer components, simpler circuitry, lower cost, and smaller size, making it a common switching voltage topology for chargers. Low-voltage electrical load devices, especially some small smart home devices, increasingly use lithium batteries to improve power efficiency and reduce size. A fundamental requirement for lithium battery charging is providing a specific charging current / voltage to ensure safe charging. Typically, after a lithium battery is fully charged, if the charger and socket are not physically disconnected, the charger will continuously charge the battery with a small current. Over time, this reduces battery life and poses safety hazards, such as overcharging leading to battery deformation. Therefore, automatically disconnecting the charger after the battery is fully charged effectively improves battery life and electrical safety.

[0003] Current chargers with automatic power-off function typically disconnect the charger output after the charging device is fully charged. At this time, the charger is still working and will generate power consumption. In addition, the traditional power-off logic is to start a countdown after detecting that the charging current of the charging device has reached a certain value, and then disconnect. This method is prone to false triggering, that is, the power is disconnected before the battery is fully charged, which will affect the charging efficiency.

[0004] Chinese Patent, Publication No. CN215733523U, Publication Date: February 21, 2022, discloses an automatic power-off charger, including a charger body. The charger body is provided with a circuit board, a battery, an input terminal, and an output terminal. The circuit board includes a control module, an automatic power-off module, and a detection module. The automatic power-off module is connected to the control module, the input terminal, and the output terminal, and is used to automatically disconnect or connect the output terminal to the input terminal. The detection module is connected to the control module and the output terminal, and is used to detect the status of the output terminal and the connected device according to the control signal of the control module, and to feed back the detected signal to the control module. The battery is connected to the control module and is used to supply power to the control module, the automatic power-off module, and the detection module when the charger is disconnected from the external power source. It only disconnects the connection between the charging device and the charger, but the charger is still in working condition and will consume energy. Utility Model Content

[0005] This invention addresses the problems of incomplete power-off and arbitrary power-off judgment in existing chargers with automatic power-off functions, resulting in energy waste and poor charging performance. It provides a charger with automatic power-off capability. By placing a double-pole relay between the power supply terminal and the input terminal of the first voltage conversion module, and monitoring the output current in real time, if the output current meets the set judgment conditions, it is determined that the charger is fully charged. The central processing unit generates a power-off signal, which is controlled by the relay drive module to disconnect the double-pole relay. By cutting off power from the charger input terminal, the power-off is more thorough, ensuring that the charger consumes no power after charging is complete, thus reducing waste and ensuring the safety of the charger during power-off.

[0006] In a first aspect, one technical solution provided in this utility model embodiment is a charger that can automatically cut off power, including a first voltage conversion module, a double-pole relay, a relay drive module, a central processing unit, and a current sampling module;

[0007] One end of the double-pole relay is connected to the power supply terminal, and the other end is connected to the input terminal of the first voltage conversion module. The control terminal of the double-pole relay is connected to the output terminal of the relay drive module. The input terminal of the relay drive module is connected to the drive control terminal of the central processing unit. The data acquisition terminal of the central processing unit is connected to the output terminal of the current sampling module. The input terminal of the current sampling module is connected to the output terminal of the first voltage conversion module.

[0008] In this solution, a double-pole relay is installed between the power supply terminal and the input terminal of the first voltage conversion module. Whether the double-pole relay is closed determines whether the charger will start charging. When the device to be charged is fully charged, the power is cut off from the input terminal, which helps to reduce the power consumption of the charger when the power is cut off, thereby reducing energy waste and making the entire device safer and more reliable. The current sampling module detects the charging current of the device to be charged to determine whether the device is fully charged, which reduces the probability of accidental power cut-off and thus improves the reliability of the charger.

[0009] Preferably, the current sampling module collects the output current of the first voltage conversion module in real time, generates a current sampling signal, sends it to the central processing unit for numerical judgment, and generates a power-off signal if the output current is continuously less than the output threshold within a set time range, and controls the double-pole relay to disconnect through the relay drive module.

[0010] In this solution, the output current of the first voltage conversion module is monitored in real time by the current sampling module. If the output current is lower than the set threshold, a low level is generated. If the low level is maintained for a period of time, the central processing unit determines that the device to be charged is fully charged and generates a power-off signal to control the double-pole relay to disconnect. By judging multiple current sampling points, the probability of false judgment is reduced, thereby improving the accuracy of judging whether the device is fully charged and improving the charging reliability of the charger.

[0011] Preferably, the first voltage conversion module includes a first AC-DC conversion module and a DC-DC conversion module. The first AC-DC conversion module adopts a flyback switching power supply topology and combines an AC-DC conversion circuit to convert the power supply current at the power supply end into DC current. The DC-DC conversion module converts DC current into charging current based on charging requirements and combines a DC-DC conversion circuit.

[0012] In this solution, since the signal at the input interface is 220V AC, and the charging device targeted by this application is a low-voltage electrical load device, it is necessary to convert the 220V AC to meet the charging requirements of the low-voltage electrical load device. First, the 220V AC is converted to 21V DC through an AC-DC conversion circuit, and then the 21V DC is converted to a charging signal that meets the charging requirements of the device to be charged through a DC-DC conversion circuit. The solution incorporates a flyback switching power supply topology to isolate the output side from the input side, ensuring the safety of the output end.

[0013] Preferably, the output terminal of the first voltage conversion module includes a USB Type-A output port or a USB Type-C output port; the current sampling module includes a sampling resistor, the first end of which is connected to the ground terminal of the output terminal of the first voltage conversion module, and the second end is grounded.

[0014] In this solution, since most low-voltage electrical load devices currently use USB interfaces for charging, the first voltage conversion module converts the 220V AC signal into a signal that meets the standard USB power input requirements, such as 5V, 9V, 12V, 20V, etc., when providing the charging signal. The sampling resistor is set in the circuit loop at the output end of the first voltage conversion module. Since the central processing unit needs to analyze the charging current, the voltage signal is converted into a current signal through the sampling resistor for easy judgment. The current sampling module samples this signal, and then the central processing unit analyzes it to determine whether it is fully charged, making the judgment process simpler.

[0015] Preferably, the current sampling module further includes an operational amplifier circuit and an optocoupler circuit. The inverting input terminal of the operational amplifier in the operational amplifier circuit is connected to the second terminal of the sampling resistor, the non-inverting input terminal is connected to the first terminal of the sampling resistor, and the output terminal is connected to the input terminal of the optocoupler circuit. The optocoupler circuit outputs a current sampling signal after noise isolation of the signal output by the operational amplifier.

[0016] In this solution, the current sampling module needs to sample the charging signal at the output interface. When fully charged, the charging current becomes very small. Therefore, to facilitate the central processing unit's judgment, the sampled charging current needs to be amplified. Thus, an operational amplifier circuit is used to convert the charging current signal into a PWM signal and set a judgment threshold. When the threshold is exceeded, the PWM signal is high; when it is less than the threshold, the PWM signal is low. Electrical isolation is then achieved through an optocoupler in the optocoupler circuit to block interference between digital ground and analog ground, reducing the impact of noise and obtaining the current sampling signal. The central processing unit only needs to know the duty cycle of the current sampling signal to determine whether the battery is fully charged, thereby improving the detection accuracy.

[0017] Preferably, the relay driving module includes a driving switch transistor and a coil. The base of the driving switch transistor is connected to the driving control terminal of the central processing unit, the collector is connected to the coil, and the emitter is grounded. If the central processing unit outputs a power-off signal, the driving switch transistor is turned off, the coil is de-energized, and the double-pole relay is disconnected.

[0018] In this design, the two single-pole switches of the double-pole relay are connected to the live and neutral wires of the input interface, respectively. When charging, the drive switch in the relay driver module is turned on, energizing the coil and attracting the double-pole relay. At this time, the input interface is connected to the first voltage conversion module, and charging is initiated. When power needs to be cut off, the drive switch in the relay driver module is turned off, de-energizing the coil and disconnecting the double-pole relay. This disconnects the input interface from the charging module, thus cutting off the power. By completely stopping the charger's operation through power-off at the input, its standby power consumption is reduced, energy waste is minimized, and the overall safety and reliability of the charger are improved.

[0019] Preferably, the system also includes a second voltage conversion module, which comprises a second AC-DC conversion module and an LDO module. The input terminal of the second AC-DC conversion module is connected to the power supply terminal, and the output terminal is connected to the input terminal of the LDO module.

[0020] The second AC-DC conversion module converts the supply current into a first drive signal through a step-down non-isolated circuit, and the LDO module converts the first drive signal into a second drive signal.

[0021] The first drive signal is used to power the relay drive module, and the second drive signal is used to power the central processing unit.

[0022] In this solution, since the driving signals required by each module in the charger are different, a second voltage conversion module is set up to enable each module to work properly. The second voltage conversion module converts the 220V AC power at the power supply end to obtain the first driving signal and the second driving signal, which are used to drive the module with the corresponding driving voltage, so that each module can work properly.

[0023] Preferably, the system also includes a reset module, which includes a reset button and a reset circuit module. The reset circuit module includes a reset capacitor, with a first end connected to the reset terminal of the central processing unit and a second end grounded. The reset button is connected in parallel with the reset capacitor.

[0024] In this solution, to prevent accidental activation or malfunction after the charger is powered off, which could cause the power-off to fail and thus re-enter the charging state, a reset module is set up. This module uses a manual physical button to avoid incomplete power-off caused by internal circuit failure of the charger, which could affect the battery's lifespan.

[0025] Preferably, when the reset button is pressed, a reset level is generated. The reset circuit module sends the reset level to the central processing unit. The central processing unit generates a reset signal based on the reset level and controls the double-pole relay to close through the relay drive module.

[0026] In this solution, the reconnection method after disconnection is stable and reliable. Before another device is connected to the charger, the reset button needs to be pressed manually. This method using a manual physical button is more human-machine interface, more reliable, and simple to use.

[0027] Preferably, the first driving signal is a DC 12V signal and the second driving signal is a DC 3.3V signal.

[0028] In this scheme, since the relay drive module requires 12V voltage for driving, the second AC-DC conversion module in the second voltage conversion module converts the 220V AC signal at the power supply end into a 12V DC signal as the first drive signal to provide drive voltage to the relay drive module. Since the central processing unit is selected as an MCU or other device, its drive voltage is 3.3V. Therefore, the LDO module converts the 12V DC signal into a 3.3V DC signal to provide drive voltage to the medium voltage processor module.

[0029] The beneficial effects of this utility model are: (1) This utility model sets a double-pole relay between the power supply end and the input end of the first voltage conversion module. Whether the double-pole relay is closed determines whether the charger performs a charging action. When the device to be charged is fully charged, the power is cut off from the input end, which helps to reduce the power consumption of the charger when the power is cut off, thereby reducing energy waste and making the whole device safer and more reliable.

[0030] (2) This utility model determines whether the device is fully charged by detecting that the charging current of the device to be charged is continuously less than a certain value for a period of time. It makes judgments on multiple current sampling points, which reduces the probability of false judgments and thus improves the accuracy of judging whether the device is fully charged.

[0031] (3) Before a device to be charged is connected to the charger again, the reset button needs to be pressed manually. This method of using a physical button avoids the situation where the power is not completely cut off due to the internal circuit failure of the charger, which affects the battery life. The human-machine interface is more reasonable, the reliability is high, it is simple and practical, and the method of reconnecting after disconnection is stable and reliable.

[0032] The above description of the utility model is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more obvious and understandable, specific embodiments of this utility model are described below. Attached Figure Description

[0033] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. The drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0034] Figure 1 This is a schematic diagram of the principle of a charger with automatic power-off capability according to the present invention.

[0035] Figure 2 This is a circuit diagram of the first part of the first AC-DC conversion module of this utility model;

[0036] Figure 3 This is the circuit diagram of the second part of the first AC-DC conversion module of this utility model;

[0037] Figure 4 This is a circuit diagram of the DC-DC conversion module and its output terminal of this utility model;

[0038] Figure 5 This is a circuit diagram of the current sampling module of this utility model;

[0039] Figure 6 This is a circuit diagram of the driving circuit for the central processing unit of this utility model;

[0040] Figure 7 This is a circuit diagram of the relay drive module of this utility model;

[0041] Figure 8 This is a schematic diagram of embodiment 2 of the present invention;

[0042] Figure 9 This is a circuit diagram of the second AC-DC conversion module of this utility model;

[0043] Figure 10 This is the circuit diagram of the LDO module of this utility model;

[0044] Figure 11 This is a schematic diagram of embodiment 3 of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only one preferred embodiment of this utility model and are only used to explain this utility model. They do not limit the scope of protection of this utility model. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0046] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations (or steps) as sequential processes, many of the operations (or steps) can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it may also have additional steps not included in the figures; the process may correspond to a method, function, procedure, subroutine, subroutine, etc.

[0047] Example 1: As Figure 1 As shown, in order to solve the problems of energy waste and poor charging effect caused by incomplete power disconnection and arbitrary power disconnection judgment in existing chargers with automatic power disconnection function, this embodiment provides a charger with automatic power disconnection, including a first voltage conversion module, a double-pole relay, a relay drive module, a central processing unit and a current sampling module.

[0048] One end of the double-pole relay is connected to the power supply terminal, and the other end is connected to the input terminal of the first voltage conversion module. The control terminal of the double-pole relay is connected to the output terminal of the relay drive module. The input terminal of the relay drive module is connected to the drive control terminal of the central processing unit. The data acquisition terminal of the central processing unit is connected to the output terminal of the current sampling module. The input terminal of the current sampling module is connected to the output terminal of the first voltage conversion module.

[0049] In this embodiment, the current sampling module collects the output current of the first voltage conversion module in real time, generates a current sampling signal, sends it to the central processing unit for numerical judgment, and generates a power-off signal if the output current is continuously less than the output threshold within a set time range, and controls the double-pole relay to disconnect through the relay driving module.

[0050] In this embodiment, the output current of the first voltage conversion module is monitored in real time by the current sampling module. If the output current is lower than the set threshold, a low level is generated. If the low level is maintained for a period of time, the central processing unit determines that the device to be charged is fully charged and generates a power-off signal to control the double-pole relay to disconnect. By judging multiple current sampling points, the probability of false judgment is reduced, thereby improving the accuracy of judging whether the device is fully charged and improving the charging reliability of the charger.

[0051] In this embodiment, the first voltage conversion module includes a first AC-DC conversion module and a DC-DC conversion module. The AC-DC conversion module adopts a flyback switching power supply topology and combines an AC-DC conversion circuit to convert the power supply current at the power supply end into DC current. The DC-DC conversion module converts DC current into charging current based on charging requirements and combines a DC-DC conversion circuit.

[0052] Specifically, the specific circuit structure of the first AC-DC conversion module is as follows: Figure 2 and Figure 3 As shown, the system includes a first rectifier bridge DB1, a control chip U1, a voltage regulator U3, a transformer T1, and an optocoupler U2. The rectifier bridge DB1 converts the 220V AC signal from the power supply into a pulsating DC signal. The control chip U1 controls the conduction of the switching transistor, and the transformer T1 converts the pulsating DC signal into the required voltage signal. The optocoupler U2 isolates the input and output terminals to ensure output safety and works with the voltage regulator U3 to feed the output DC signal back to the control chip U1 to ensure the stability of the output signal.

[0053] Specifically, the circuit structure of the DC-DC conversion module and its output terminal in this embodiment is as follows: Figure 4As shown, the power management chip U6 detects the interface type of the connected charging device to determine the required charging signal strength. After determination, the power management chip U6 converts the DC 21V signal provided by the first power supply module into a charging signal corresponding to the charging device, such as 5V, 9V, 12V, 20V, etc., to provide charging services for the charging device.

[0054] Since most low-voltage electrical load devices use USB interfaces for charging, and most of them require USB power input between 5V and 20V, the 220V AC signal is converted into a DC 21V signal. Based on the DC 21V signal, the USB power input voltage is converted to meet the charging needs of most devices.

[0055] Since the power supply current at the power supply end in this embodiment is 220V AC, and the charging device in this embodiment is a low-voltage electrical load device, it is necessary to convert the 220V AC to meet the charging requirements of the low-voltage electrical load device. First, the 220V AC is converted to 21V DC through an AC-DC conversion module, and then the 21V DC is converted to a charging signal that meets the charging requirements of the device to be charged through a DC-DC conversion module. In this embodiment, a flyback switching power supply topology is used to isolate the output side from the input side, ensuring the safety of the output end.

[0056] In this embodiment, the output terminal of the first voltage conversion module includes a USB Type-A output port or a USB Type-C output port; the current sampling module includes a sampling resistor, the first end of which is connected to the ground terminal of the output terminal of the first voltage conversion module, and the second end is grounded. Specifically, as shown... Figure 4 As shown in the figure, R28 is the sampling resistor.

[0057] In this embodiment, since most low-voltage electrical load devices currently use USB interfaces for charging, the first voltage conversion module converts the 220V AC signal into a signal that meets the standard USB power input requirements, such as 5V, 9V, 12V, 20V, etc., when providing the charging signal. The sampling resistor is set in the circuit loop at the output end of the first voltage conversion module. Since the central processing unit needs to analyze the charging current, the voltage signal is converted into a current signal through the sampling resistor for easy judgment. The current sampling module samples this signal, and then the central processing unit analyzes it to determine whether it is fully charged, making the judgment process simpler.

[0058] In this embodiment, as Figure 5As shown, the current sampling module further includes an operational amplifier circuit and an optocoupler circuit. The inverting input terminal of the operational amplifier in the operational amplifier circuit is connected to the second terminal of the sampling resistor, the non-inverting input terminal is connected to the first terminal of the sampling resistor, and the output terminal is connected to the input terminal of the optocoupler circuit. The optocoupler circuit outputs a current sampling signal after noise isolation of the signal output by the operational amplifier.

[0059] In this embodiment, the current sampling module needs to sample the charging signal at the output interface. When fully charged, the charging current becomes very small. Therefore, to facilitate the central processing unit's judgment, the sampled charging current needs to be amplified. Thus, an operational amplifier circuit is used to convert the charging current signal into a PWM signal and set a judgment threshold. When the threshold is exceeded, the PWM signal is high; when it is less than the threshold, the PWM signal is low. Electrical isolation is then achieved through an optocoupler in the optocoupler circuit to block interference between digital ground and analog ground, reducing the impact of noise and obtaining the current sampling signal. The central processing unit only needs to know the duty cycle of the current sampling signal to determine whether the battery is fully charged, thereby improving the detection accuracy.

[0060] In this embodiment, as Figure 6 and Figure 7 As shown, the relay driving module includes a driving switch Q1 and a coil JD1. The base of the driving switch is connected to the driving control terminal PB2 of the central processing unit, the collector is connected to the coil, and the emitter is grounded. If the central processing unit outputs a power-off signal, the driving switch is turned off, the coil is de-energized, and the double-pole relay is disconnected.

[0061] In this embodiment, the two single-pole switches of the double-pole relay are connected to the live and neutral wires of the input interface, respectively. When in charging mode, the drive switch in the relay driver module is turned on, and the coil is energized to attract the double-pole relay. At this time, the input interface is connected to the first voltage conversion module to perform the charging action. When power needs to be cut off, the drive switch in the relay driver module is turned off, and the coil is de-energized to disconnect the double-pole relay. At this time, the input interface is disconnected from the charging module to perform the power-off action. By cutting off the power at the input end, the operation of the charger is completely stopped, reducing its standby power consumption, reducing energy waste, and improving the safety and reliability of the entire charger.

[0062] Example 2: As Figure 8As shown, this embodiment, in order to further integrate the internal structure of the charger, integrates the power supply of the internal relay drive module and the central processing unit based on embodiment 1. It includes a first voltage conversion module, a double-pole relay, a relay drive module, a central processing unit, a current sampling module, and a second voltage conversion module. One end of the double-pole relay is connected to the power supply terminal, and the other end is connected to the input terminal of the first voltage conversion module. The control terminal of the double-pole relay is connected to the output terminal of the relay drive module. The input terminal of the relay drive module is connected to the drive control terminal of the central processing unit. The data acquisition terminal of the central processing unit is connected to the output terminal of the current sampling module. The input terminal of the module is connected to the output terminal of the first voltage conversion module; the second voltage conversion module includes a second AC-DC conversion module and an LDO module, the input terminal of the second AC-DC conversion module is connected to the power supply terminal, and the output terminal is connected to the input terminal of the LDO module; the second AC-DC conversion module converts the power supply current into a first drive signal through a step-down non-isolated circuit, and the LDO module converts the first drive signal into a second drive signal; the first drive signal is used to power the relay drive module, and the second drive signal is used to power the central processing unit; the first drive signal is a DC 12V signal, and the second drive signal is a DC 3.3V signal.

[0063] Specifically, such as Figure 9 The diagram shown is a circuit diagram of the second AC-DC conversion module in this embodiment, including a second rectifier bridge DB2 and a switching regulator U9. The second rectifier bridge DB2 converts the 220V AC signal from the input interface 1 into a pulsating DC signal, and the input signal is filtered by a filter capacitor. The filtered signal is then controlled by the switching regulator U9 to store and release energy in the energy storage inductors L4 and L5 to adjust the output voltage. Finally, the output capacitor C23 outputs the required 12V DC signal as the first drive signal.

[0064] Specifically, such as Figure 10 The diagram shows the specific circuit structure of the LDO module, which is used to convert a 12V DC signal into a 3.3V DC signal for output via the voltage conversion chip U7.

[0065] In this embodiment, since the relay drive module requires 12V voltage for driving, the power supply module converts the 1220V AC signal from the input interface into a 12V DC signal as the first drive signal to provide the drive voltage to the relay drive module. Since the central processing unit module is selected as an MCU or other device, its drive voltage is 3.3V. Therefore, the power supply module converts the 12V DC signal into a 3.3V DC signal to provide the drive voltage to the medium voltage processor module.

[0066] In this embodiment, since the driving voltage required by each module in the charger is different, a power supply module is set up to enable each module to work normally. The power supply module converts the 220V AC power at the input terminal to obtain a first driving signal and a second driving signal, which are used to drive the module with the corresponding driving voltage, so that each module can work normally.

[0067] Example 3: As Figure 11 As shown, this embodiment adds a reset module based on Embodiments 1 and 2. The specific structure includes a first voltage conversion module, a double-pole relay, a relay drive module, a central processing unit, a current sampling module, and a reset module.

[0068] One end of the double-pole relay is connected to the power supply terminal, and the other end is connected to the input terminal of the first voltage conversion module. The control terminal of the double-pole relay is connected to the output terminal of the relay drive module. The input terminal of the relay drive module is connected to the drive control terminal of the central processing unit. The data acquisition terminal of the central processing unit is connected to the output terminal of the current sampling module. The input terminal of the current sampling module is connected to the output terminal of the first voltage conversion module.

[0069] The reset module includes a reset button and a reset circuit module. The reset circuit module includes a reset capacitor. The first end of the reset capacitor is connected to the central processing unit, and the second end is grounded. The reset button is connected in parallel with the reset capacitor.

[0070] Specifically, such as Figure 6 As shown, the PB3 interface of the MCU (i.e., U5) in the central processing unit is connected to the reset module. The PB1 interface of the MCU is connected to the current sampling module to collect the current sampling signal and analyze it. If the current signal is continuously less than a certain value, such as 20mA, for a period of time (e.g., 60s), it is determined that the battery is fully charged, and a power-off signal is generated and sent to the relay drive module through the PB2 interface.

[0071] In this embodiment, to prevent accidental activation or malfunction after the charger is powered off, which could lead to failure to re-enter the charging state, a reset module is provided. This module uses a manual physical button to avoid incomplete power disconnection due to internal circuit failure of the charger, thus preventing impact on battery life.

[0072] In this embodiment, when the reset button is pressed, a reset level is generated. The reset circuit module sends the reset level to the central processing unit. The central processing unit generates a reset signal and controls the double-pole relay to close through the relay drive module.

[0073] Specifically, when the reset button is pressed, the generated reset level is sent to the PB3 interface of the MCU, and the MCU generates a reset signal and sends it to the relay driver module through the PB2 interface.

[0074] The reconnection method in this embodiment is stable and reliable. Before another device is connected to the charger, the reset button needs to be pressed manually. This method using a manual physical button is more human-machine interface, more reliable, and simple to use.

[0075] As can be seen from the above embodiments, it has at least the following substantial effects:

[0076] (1) This utility model sets a double-pole relay between the power supply end and the input end of the first voltage conversion module. Whether the double-pole relay is closed determines whether the charger performs a charging action. When the device to be charged is fully charged, the power is cut off from the input end, which helps to reduce the power consumption of the charger when the power is cut off, thereby reducing energy waste and making the whole device safer and more reliable.

[0077] (2) This utility model determines whether the device is fully charged by detecting that the charging current of the device to be charged is continuously less than a certain value for a period of time. It makes judgments on multiple current sampling points, which reduces the probability of false judgments and thus improves the accuracy of judging whether the device is fully charged.

[0078] (3) Before a device to be charged is connected to the charger again, the reset button needs to be pressed manually. This method of using a physical button avoids the situation where the power is not completely cut off due to the internal circuit failure of the charger, which affects the battery life. The human-machine interface is more reasonable, the reliability is high, it is simple and practical, and the method of reconnecting after disconnection is stable and reliable.

[0079] The above-described specific embodiments are preferred embodiments of the charger with automatic power-off capability of this utility model, and are not intended to limit the specific scope of this utility model. The scope of this utility model includes but is not limited to the specific embodiments described above. All equivalent changes made in accordance with the shape and structure of this utility model are within the protection scope of this utility model.

Claims

1. A charger with automatic power-off capability, comprising a first voltage conversion module, characterized in that: It also includes a double-pole relay, a relay driver module, a central processing unit, and a current sampling module; One end of the double-pole relay is connected to the power supply terminal, and the other end is connected to the input terminal of the first voltage conversion module. The control terminal of the double-pole relay is connected to the output terminal of the relay drive module. The input terminal of the relay drive module is connected to the drive control terminal of the central processing unit. The data acquisition terminal of the central processing unit is connected to the output terminal of the current sampling module. The input terminal of the current sampling module is connected to the output terminal of the first voltage conversion module.

2. The charger with automatic power-off capability according to claim 1, characterized in that: The current sampling module collects the output current of the first voltage conversion module in real time, generates a current sampling signal, and sends it to the central processing unit for numerical judgment. If the output current is continuously less than the output threshold within a set time range, a power-off signal is generated, and the double-pole relay is controlled to disconnect through the relay drive module.

3. The charger with automatic power-off capability according to claim 1, characterized in that: The first voltage conversion module includes a first AC-DC conversion module and a DC-DC conversion module. The first AC-DC conversion module adopts a flyback switching power supply topology and combines an AC-DC conversion circuit to convert the power supply current at the power supply end into DC current. The DC-DC conversion module converts DC current into charging current based on charging requirements and combines a DC-DC conversion circuit.

4. The charger with automatic power-off capability according to claim 1, characterized in that: The output terminal of the first voltage conversion module includes a USB Type-A output port or a USB Type-C output port; the current sampling module includes a sampling resistor, the first end of which is connected to the ground terminal of the output terminal of the first voltage conversion module, and the second end is grounded.

5. A charger with automatic power-off capability according to claim 4, characterized in that: The current sampling module also includes an operational amplifier circuit and an optocoupler circuit. The inverting input terminal of the operational amplifier in the operational amplifier circuit is connected to the second terminal of the sampling resistor, the non-inverting input terminal is connected to the first terminal of the sampling resistor, and the output terminal is connected to the input terminal of the optocoupler circuit. The optocoupler circuit outputs a current sampling signal after noise isolation of the signal output by the operational amplifier.

6. A charger with automatic power-off capability according to claim 1, characterized in that: The relay driving module includes a driving switch transistor and a coil. The base of the driving switch transistor is connected to the driving control terminal of the central processing unit, the collector is connected to the coil, and the emitter is grounded. If the central processing unit outputs a power-off signal, the driving switch transistor is turned off, the coil is de-energized, and the double-pole relay is disconnected.

7. A charger with automatic power-off capability according to claim 1, characterized in that: It also includes a second voltage conversion module, which includes a second AC-DC conversion module and an LDO module. The input terminal of the second AC-DC conversion module is connected to the power supply terminal, and the output terminal is connected to the input terminal of the LDO module. The second AC-DC conversion module converts the supply current into a first drive signal through a step-down non-isolated circuit, and the LDO module converts the first drive signal into a second drive signal. The first drive signal is used to power the relay drive module, and the second drive signal is used to power the central processing unit.

8. A charger with automatic power-off capability according to claim 1, characterized in that: It also includes a reset module, which includes a reset button and a reset circuit module. The reset circuit module includes a reset capacitor. The first end of the reset capacitor is connected to the reset terminal of the central processing unit, and the second end is grounded. The reset button is connected in parallel with the reset capacitor.

9. A charger with automatic power-off capability according to claim 8, characterized in that: When the reset button is pressed, a reset level is generated. The reset circuit module sends the reset level to the central processing unit. The central processing unit generates a reset signal based on the reset level and controls the double-pole relay to close through the relay drive module.

10. A charger with automatic power-off capability according to claim 7, characterized in that: The first drive signal is a DC 12V signal, and the second drive signal is a DC 3.3V signal.

Images