Power supply protection circuit and charger

Abstract

The application provides a power supply protection circuit and a charger. The power supply protection circuit comprises: an input circuit for inputting a voltage; a temperature protection switch connected with the input circuit; a rectification and filtering circuit connected with the temperature protection switch, used for rectifying and filtering the input voltage, the rectification and filtering circuit comprising an electrolytic capacitor, and a conductor region surrounding the electrolytic capacitor is provided; and a switch unit connected in parallel at two ends of the electrolytic capacitor, a control end of the switch unit being connected with the conductor region, when the conductor region has a voltage, the voltage drives the switch unit to be turned on, so that the two ends of the electrolytic capacitor are short-circuited. The power supply protection circuit provided by the application can detect the voltage of the conductor region when electrolyte of the electrolytic capacitor is sprayed, drive the switch unit to be turned on, make the two ends of the electrolytic capacitor short-circuited, and thus trigger the protection action of the temperature protection switch, so that the L line and the N line of the input circuit are disconnected, and the protection function is realized.

Description

Technical Field

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

[0002] Electrolytic capacitors are essential for filtering in switching power supplies such as chargers. Among all electronic components, electrolytic capacitors have the highest failure rate, typically manifesting as the capacitor bursting and electrolyte leakage. When electrolyte is sprayed onto the primary and secondary coils of the power supply, the voltage at the input terminal leaks to the output terminal, resulting in a large leakage current at the output terminal. This can easily cause safety accidents and personal injury to users. Utility Model Content

[0003] This application provides a power protection circuit and charger. When the electrolyte of an electrolytic capacitor is ejected, the circuit can detect the voltage and short-circuit the two ends of the electrolytic capacitor, thereby triggering the protection action of the temperature protection switch to prevent safety accidents and improve the safety of the circuit.

[0004] This application provides a power protection circuit, including: Input circuit, used for input voltage; A temperature protection switch is connected to the input circuit. A rectifier and filter circuit, connected to the temperature protection switch, is used to rectify and filter the input voltage. The rectifier and filter circuit includes an electrolytic capacitor, and a floating conductor area is provided around the electrolytic capacitor. A switching unit is connected in parallel across the two ends of the electrolytic capacitor. The control terminal of the switching unit is connected to the conductor region. When there is voltage in the conductor region, the voltage drives the switching unit to conduct, thereby short-circuiting the two ends of the electrolytic capacitor.

[0005] In some embodiments, the power protection circuit further includes a voltage limiting circuit connected between the control terminal of the switching unit and the conductor region, for limiting the voltage at the control terminal of the switching unit.

[0006] In some embodiments, the voltage limiting circuit includes a resistor and a Zener diode. The resistor is connected between the control terminal of the switching unit and the conductor region. The cathode of the Zener diode is connected between the resistor and the control terminal of the switching unit. The anode of the Zener diode is connected to the negative terminal of the electrolytic capacitor and grounded.

[0007] In some embodiments, the resistance value of the resistor is between 1kΩ and 4.7kΩ, and the voltage regulation value of the Zener diode is 5.1V.

[0008] In some embodiments, the switching unit is a MOS transistor, the gate of the MOS transistor is connected to the conductor region, the source of the MOS transistor is connected to the negative terminal of the electrolytic capacitor and grounded, and the drain of the MOS transistor is connected to the positive terminal of the electrolytic capacitor.

[0009] In some embodiments, the electrolytic capacitor operates at 450V, the MOSFET has a withstand voltage greater than 450V, and the MOSFET's avalanche energy is greater than the temperature protection switch's disconnection energy.

[0010] In some embodiments, the temperature protection switch is a dual-channel linkage switch, which includes a first switch and a second switch that are linked together. The first switch is connected in series in one line of the input circuit, and the second switch is connected in series in the other line of the input circuit.

[0011] In some embodiments, the rectifier filter circuit further includes a rectifier circuit connected to the temperature protection switch, and the electrolytic capacitor is connected to the rectifier circuit.

[0012] In some embodiments, the conductor region is bare copper foil.

[0013] This application also provides a charger, including the power protection circuit of any of the above embodiments.

[0014] The power protection circuit of this application embodiment has a conductive area around the electrolytic capacitor. When the electrolyte of the electrolytic capacitor is ejected, the conductive area can detect the voltage and drive the switching unit to conduct, causing a short circuit at both ends of the electrolytic capacitor, thereby triggering the protection action of the temperature protection switch, disconnecting the L line and N line of the input circuit, playing a protective role, preventing safety accidents, and improving the safety of the circuit. Attached Figure Description

[0015] 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.

[0016] Figure 1 This is a schematic diagram of the power protection circuit according to an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of an embodiment of the present application showing an electrolytic capacitor and conductor area disposed on a circuit board. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] This application provides a power protection circuit that can be applied to switching power supplies such as chargers. The power protection circuit can detect electrolyte leakage from an electrolytic capacitor and short-circuit the two ends of the electrolytic capacitor upon detection, thereby triggering a temperature protection switch and improving circuit safety.

[0020] refer to Figure 1 , Figure 1 This is a schematic diagram of the power protection circuit according to an embodiment of this application. The power protection circuit includes an input circuit, a temperature protection switch, a rectifier and filter circuit, and a switching unit.

[0021] The input circuit is used to input voltage, such as 220V AC voltage. In practical applications, the input circuit includes two lines, such as a live wire and a neutral wire. The live wire can be represented as the L line, and the neutral wire can be represented as the N line.

[0022] A temperature protection switch, for example, is switch S. Temperature protection switch S is connected to the input circuit. Temperature protection switch S provides over-temperature protection. For example, when a short circuit occurs, a large instantaneous current is generated in the circuit. Temperature protection switch S generates a large amount of heat in a short time, causing its temperature to rise and triggering the protection action, causing switch S to open. This disconnects the L and N lines of the input circuit, providing protection and preventing safety accidents. In some embodiments, the rated current of temperature protection switch S is greater than 1.5 times the input current, the opening time is less than 10ms, and it does not automatically recover after opening.

[0023] In some embodiments, the temperature protection switch S is a dual-channel interlocking switch. The temperature protection switch S includes a first switch S1 and a second switch S2 that are interlocked. When the protection action is triggered, the first switch S1 and the second switch S2 operate simultaneously. The first switch S1 is connected in series in one line of the input circuit, for example, in series in the neutral (N) line; the second switch S2 is connected in series in the other line of the input circuit, for example, in series in the low (L) line.

[0024] The rectifier and filter circuit is connected to the temperature protection switch S. The rectifier and filter circuit is used to rectify and filter the input voltage. It includes an electrolytic capacitor, such as electrolytic capacitor EC1. One end of electrolytic capacitor EC1 is connected to transformer T1, for example, the positive terminal (represented as +) is connected to transformer T1 to supply voltage to transformer T1. The other end of electrolytic capacitor EC1 is grounded, for example, the negative terminal (represented as -) is grounded. In some embodiments, the operating voltage of electrolytic capacitor EC1 is 450V.

[0025] The electrolytic capacitor EC1 is surrounded by a floating conductor region M. (See also...) Figure 2 , Figure 2 This is a schematic diagram illustrating the arrangement of electrolytic capacitors and conductor regions on a circuit board according to an embodiment of this application. Figure 2 As shown, electrolytic capacitor EC1 is mounted on a circuit board. EC1 includes a positive terminal and a negative terminal, and a conductive region is arranged around EC1. In practical applications, the conductive region can be regular or irregular in shape. It can surround EC1 completely, or it can be partially surrounded, for example, partially surrounded, or distributed between EC1 and other surrounding components. The specific arrangement depends on the component layout on the circuit board. "Floating" refers to the conductive region M not being connected to EC1 or any other surrounding components, thus remaining in a floating state. In some embodiments, the conductive region M is exposed copper foil, meaning exposed copper foil is arranged around EC1.

[0026] The switching unit is, for example, Q1. Switching unit Q1 is connected in parallel across the electrolytic capacitor EC1, meaning one end of switching unit Q1 is connected to the positive terminal of electrolytic capacitor EC1, and the other end is connected to the negative terminal of electrolytic capacitor EC1. Switching unit Q1 has a control terminal, which is connected to the conductor region M. When there is voltage in conductor region M, the voltage drives switching unit Q1 to conduct, short-circuiting the two ends of electrolytic capacitor EC1. Due to the short circuit of electrolytic capacitor EC1, a large instantaneous current is generated in the circuit. The temperature protection switch S generates a large amount of heat in a short time, causing the temperature to rise, thereby triggering the protection action and causing switch S to open. This disconnects the L and N lines of the input circuit, providing protection and preventing safety accidents.

[0027] Understandably, when electrolytic capacitor EC1 fails and electrolyte is sprayed, the conductive area M around electrolytic capacitor EC1 will be sprayed immediately. Since electrolyte is also a conductive liquid, the operating voltage of the surrounding devices will be conducted to the conductive area M, and then through the conductive area M to the control terminal of the switching unit Q1, causing the switching unit Q1 to conduct, thereby triggering the protection action of the temperature protection switch S, thus preventing a safety accident caused by the failure of electrolytic capacitor EC1.

[0028] In some embodiments, the switching unit Q1 is a MOSFET, and the gate of the MOSFET Q1 is the control terminal. The gate of the MOSFET Q1 is connected to the conductor region M, the source of the MOSFET Q1 is connected to the negative terminal (-) of the electrolytic capacitor EC1 and grounded, and the drain of the MOSFET Q1 is connected to the positive terminal (+) of the electrolytic capacitor EC1.

[0029] In some embodiments, the withstand voltage of MOSFET Q1 is greater than the operating voltage of electrolytic capacitor EC1 (450V), the avalanche energy of MOSFET Q1 is greater than the breaking energy of temperature protection switch S, and the package size of MOSFET Q1 is DFN5*6 or larger. Therefore, normal operation of MOSFET Q1 can be guaranteed.

[0030] In some embodiments, continue to refer to Figure 1 The power protection circuit also includes a voltage limiting circuit. This voltage limiting circuit is connected between the control terminal of the switching unit Q1 and the conductor region M, for example, between the gate of the MOSFET Q1 and the conductor region M. The voltage limiting circuit is used to limit the voltage at the control terminal of the switching unit Q1.

[0031] Understandably, in practical applications, many devices are arranged around the electrolytic capacitor EC1, each with different operating voltages—some low, some high. If electrolyte is sprayed onto a device with a low operating voltage, the voltage in conductor region M will also be low; conversely, if electrolyte is sprayed onto a device with a high operating voltage, the voltage in conductor region M will also be high. Therefore, the voltage in conductor region M is uncontrollable. To prevent excessively high voltage from damaging the switching unit Q1, a voltage limiting circuit is needed to limit the voltage at the control terminal of the switching unit Q1.

[0032] In some embodiments, the voltage limiting circuit includes a resistor and a Zener diode, such as resistor R1 and Zener diode D1. Resistor R1 is connected between the control terminal of switching unit Q1 and conductor region M, and serves to limit current. The cathode of Zener diode D1 is connected between resistor R1 and the control terminal of switching unit Q1, and the anode of Zener diode D1 is connected to the negative terminal of electrolytic capacitor EC1 and grounded. Through the current limiting effect of resistor R1 and the voltage regulation of Zener diode D1, the control terminal of switching unit Q1 can receive a normal driving voltage, preventing damage to switching unit Q1 due to excessively high voltage.

[0033] In some embodiments, the resistance of resistor R1 is between 1kΩ and 4.7kΩ. The voltage regulation value of Zener diode D1 is 5.1V.

[0034] In some embodiments, such as Figure 1As shown, the power protection circuit also includes a rectifier circuit, such as rectifier circuit BD1. Rectifier circuit BD1 is connected to the temperature protection switch S, and electrolytic capacitor EC1 is connected to rectifier circuit BD1. Rectifier circuit BD1 is used to rectify the input voltage.

[0035] In some embodiments, the rectifier circuit BD1 can be a bridge rectifier circuit composed of four diodes. The rectifier circuit BD1 includes four connection terminals 1, 2, 3, and 4. Among them, connection terminal 1 is connected to the first switch S1, connection terminal 2 is connected to the second switch S2, connection terminal 3 is connected to the negative terminal (-) of the electrolytic capacitor EC1 and grounded, and connection terminal 4 is connected to the positive terminal (+) of the electrolytic capacitor EC1.

[0036] In the power protection circuit of this application embodiment, a conductor region M is provided around the electrolytic capacitor EC1. When the electrolyte of the electrolytic capacitor EC1 is ejected, the conductor region M can detect the voltage and drive the switching unit Q1 to conduct, causing a short circuit across the two ends of the electrolytic capacitor EC1, thereby triggering the protection action of the temperature protection switch S, disconnecting the L line and N line of the input circuit, playing a protective role, preventing safety accidents, and improving the safety of the circuit.

[0037] This application also provides a charger, including the power protection circuit of any of the above embodiments.

[0038] In the description of this application, it should be understood that terms such as “first” and “second” are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0039] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0040] The power protection circuit and charger provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A power supply protection circuit, characterized in that, include: Input circuit, used for input voltage; A temperature protection switch is connected to the input circuit. A rectifier and filter circuit, connected to the temperature protection switch, is used to rectify and filter the input voltage. The rectifier and filter circuit includes an electrolytic capacitor, and a floating conductor area is provided around the electrolytic capacitor. A switching unit is connected in parallel across the two ends of the electrolytic capacitor. The control terminal of the switching unit is connected to the conductor region. When there is voltage in the conductor region, the voltage drives the switching unit to conduct, thereby short-circuiting the two ends of the electrolytic capacitor.

2. The power protection circuit according to claim 1, characterized in that, It also includes a voltage limiting circuit connected between the control terminal of the switching unit and the conductor region, used to limit the voltage at the control terminal of the switching unit.

3. The power protection circuit according to claim 2, characterized in that, The voltage limiting circuit includes a resistor and a Zener diode. The resistor is connected between the control terminal of the switching unit and the conductor region. The cathode of the Zener diode is connected between the resistor and the control terminal of the switching unit. The anode of the Zener diode is connected to the negative terminal of the electrolytic capacitor and grounded.

4. The power protection circuit according to claim 3, characterized in that, The resistance of the resistor is between 1kΩ and 4.7kΩ, and the voltage regulation value of the Zener diode is 5.1V.

5. The power protection circuit according to claim 1, characterized in that, The switching unit is a MOSFET, the gate of the MOSFET is connected to the conductor region, the source of the MOSFET is connected to the negative terminal of the electrolytic capacitor and grounded, and the drain of the MOSFET is connected to the positive terminal of the electrolytic capacitor.

6. The power protection circuit according to claim 5, characterized in that, The electrolytic capacitor operates at 450V, the MOSFET has a withstand voltage greater than 450V, and the avalanche energy of the MOSFET is greater than the disconnection energy of the temperature protection switch.

7. The power protection circuit according to any one of claims 1 to 6, characterized in that, The temperature protection switch is a dual-channel linkage switch, which includes a first switch and a second switch that are linked together. The first switch is connected in series in one line of the input circuit, and the second switch is connected in series in the other line of the input circuit.

8. The power protection circuit according to any one of claims 1 to 6, characterized in that, The rectifier and filter circuit further includes a rectifier circuit, which is connected to the temperature protection switch, and the electrolytic capacitor is connected to the rectifier circuit.

9. The power protection circuit according to any one of claims 1 to 6, characterized in that, The conductor region is bare copper foil.

10. A charger, characterized in that, Includes the power protection circuit as described in any one of claims 1 to 9.

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