Charging protection circuit and charger

Abstract

The invention discloses a charging protection circuit and a charger, and belongs to the technical field of charging. The charging protection circuit comprises a power supply, a rectifier module, a first switch tube, a current detection resistor and a current discharge module, the rectifier module is used for converting alternating current output by the power supply into direct current, and the output end of the rectifier module is electrically connected with the first end of the current detection resistor through the first switch tube; the first end of the current detection resistor is grounded, the second end of the current detection resistor is grounded, the current discharge module comprises a first switch, the input end of the first switch is electrically connected with the first end of the current detection resistor, and the output end of the first switch is electrically connected with the second end of the current detection resistor; wherein under the condition that the first switch tube is broken down, the first switch is in a conducting state.

Description

Technical Field

[0001] The present application belongs to the field of charging technology, and specifically relates to a charging protection circuit and a charger. Background Art

[0002] During the use of the charger, if the switching tube in the power circuit is broken down, that is, the drain and source of the switching tube are short-circuited, a very large transient current will be generated in the power circuit, even up to 200A or more. When the transient current passes through the power circuit, the current detection resistor in the power circuit will often fail because it cannot withstand the transient current, thereby affecting the reliability of the charger.

[0003] It can be seen that the charger in the related art has the problem of poor reliability. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a charging protection circuit and a charger, which can solve the problem of poor reliability of chargers in related technologies.

[0005] In order to solve the above technical problems, this application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a charging protection circuit, including: a power supply, a rectifier module, a first switch tube, a current detection resistor and a current discharge module, wherein the rectifier module is used to convert the alternating current output by the power supply into direct current, the output end of the rectifier module is electrically connected to the first end of the current detection resistor through the first switch tube, and the second end of the current detection resistor is grounded, the current discharge module includes a first switch, the input end of the first switch is electrically connected to the first end of the current detection resistor, and the output end of the first switch is electrically connected to the second end of the current detection resistor;

[0007] Wherein, when the first switch tube is broken down, the first switch is in an on state.

[0008] In a second aspect, an embodiment of the present application provides a charger, comprising the charging protection circuit described in the first aspect above.

[0009] In the embodiment of the present application, when the first switch tube is broken down, the first switch is placed in an on state to place the first switch in parallel with the current detection resistor in a conductive state, so that the path where the first switch is located can shunt the current in the path where the first switch tube is located in a short-circuited state, thereby preventing more current from flowing to the current detection resistor, thereby preventing the current detection resistor from failing, and further achieving the purpose of improving the reliability of the charger. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1It is one of the circuit diagrams of the charging protection circuit provided in the embodiment of the present application;

[0011] Figure 2 This is the second circuit diagram of the charging protection circuit provided in the embodiment of the present application. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0013] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0014] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a charging protection circuit, which can be applied to a charger, and the charging protection circuit includes a power supply 101, a rectifier module 102, a first switch tube 103, a current detection resistor 104 and a current discharge module 105, the rectifier module 102 is used to convert the alternating current output by the power supply 101 into direct current, the output end of the rectifier module 102 is electrically connected to the first end of the current detection resistor 104 through the first switch tube 103, the second end of the current detection resistor 104 is grounded, the current discharge module 105 includes a first switch 1051, the input end of the first switch 1051 is electrically connected to the first end of the current detection resistor 104, and the output end of the first switch 1051 is electrically connected to the second end of the current detection resistor 104;

[0015] When the first switch tube 103 is broken down, the first switch 1051 is in the on state.

[0016] The breakdown of the first switch tube 103 can be understood as the charger being in a lightning strike scenario or a high-voltage charging scenario, that is, the AC voltage output by the power supply 101 is a high voltage greater than the conventional voltage, causing the first switch tube 103 to be broken down, that is, the drain and source of the switch tube 103 are short-circuited, thereby generating a very large transient current in the path where the first switch tube 103 and the current detection resistor 104 are located. The transient current can even be as high as 200A or more, and the current detection resistor 104 often fails because it cannot withstand this transient current.

[0017] In the present application, when the first switch tube 103 is broken down, the first switch 1051 is turned on to put the first switch 1051 in parallel with the current detection resistor 104 in a conductive state, so that the path where the first switch 1051 is located can shunt the current of the path where the first switch tube 103 is located in a short-circuited state, thereby preventing more current from flowing to the current detection resistor 104, thereby preventing the current detection resistor 104 from failing, thereby achieving the purpose of improving the reliability of the charger.

[0018] In some embodiments, the power supply 101, the rectifier module 102, the first switch tube 103, the current detection resistor 104 and the current discharge module 105 can constitute a front-end circuit of the charger, and the front-end circuit of the charger also includes a first capacitor 106, a pulse width modulation module 107, a first coil winding 108 and other devices;

[0019] The charger also includes a back-end circuit, which includes a power output terminal 201, a second coil winding 202, a second capacitor 203, a second switch tube 204, a protocol control module 205, a synchronous rectification drive module 206 and other components;

[0020] The second coil winding 202 is coupled to the first coil winding 108 , and the power output terminal 201 is used to be electrically connected to an external device to be charged.

[0021] The front-end circuit can be understood as the primary circuit of the charger for accessing the AC power supply, and the back-end circuit can be understood as the secondary circuit of the charger for accessing the charging interface of mobile phones, tablet computers and other devices waiting to be charged.

[0022] In some embodiments, the current discharge module 105 further includes a voltage detection unit 1052 and a control unit 1053, and the control unit 1053 is electrically connected to the voltage detection unit 1052 and the first switch 1051 respectively;

[0023] A voltage detection unit 1052, used to detect the voltage across the current detection resistor 104;

[0024] The control unit 1053 is used to control the first switch 1051 to be in an on state when the first switch tube 103 is broken down and the voltage detection unit 1052 detects that the voltage across the current detection resistor 104 is greater than a first preset voltage.

[0025] Since when the first switch tube 103 is broken down, the current flowing through the current detection resistor 104 will instantly increase to a maximum value, such as increased to more than 200A; therefore, the voltage across the current detection resistor 104 can be detected, and when the voltage across the current detection resistor 104 is greater than the first preset voltage, the first switch 1051 can be controlled to be in the on state.

[0026] Among them, the above-mentioned first preset voltage can be the voltage across the current detection resistor 104 when the current flowing through the current detection resistor 104 is 10A, so that when the current flowing through the current detection resistor 104 will instantly increase to a maximum value, such as increased to more than 200A, the voltage across the current detection resistor 104 will definitely be greater than the first preset voltage; in this case, by controlling the first switch 1051 to be in an on state, the path where the first switch 1051 is located can divert the current in the path where the first switch tube 103 is in a short-circuit state, which can avoid more current flowing to the current detection resistor 104, thereby avoiding failure of the current detection resistor 104, and further achieving the purpose of improving the reliability of the charger.

[0027] In some embodiments, the charging protection circuit further includes an abnormal level detection module 109 and a second switch 1010, the abnormal level detection module 109 is used to detect the voltage across the current detection resistor 104, one end of the second switch 1010 is electrically connected to the power supply 101, and the other end is short-connected to the input end of the rectifier module 102;

[0028] When the abnormal level detection module 109 detects that the voltage across the current detection resistor 104 is greater than the second preset voltage, the second switch 1010 is controlled to switch from the on state to the off state, and the second preset voltage is less than the first preset voltage.

[0029] Since one end of the second switch 1010 is electrically connected to the power supply 101 and the other end is short-connected to the input end of the rectifier module 102, when the second switch 1010 is controlled to switch from the on state to the off state, the electrical connection between the external AC power supply and the internal circuit of the charger can be cut off to prevent the charger from being further damaged.

[0030] In some embodiments, the resistance of the first switch 1051 is smaller than the resistance of the current detection resistor 104, so that the first switch 1051 in the on state can receive more current, thereby further avoiding failure of the current detection resistor 104 and achieving the purpose of improving the reliability of the charger.

[0031] In some embodiments, the charging protection circuit further includes a pulse width modulation module 107 and a current detection module 1011. The pulse width modulation module 107 can be electrically connected to the gate of the first switch tube 103. The current detection module 1011 is used to detect the voltage across the current detection resistor 104, and the current detection module 1011 is also electrically connected to the pulse width modulation module 107.

[0032] When the current detection module 1011 detects that the voltage across the current detection resistor 104 is greater than the third preset voltage, the pulse width modulation module 107 is used to control the first switch tube 103 to be in the cut-off state.

[0033] When the first switch tube 103 is not broken down, the conduction degree of the first switch tube 103 can be controlled by detecting the voltage across the current detection resistor 104, and when the current detection module 1011 detects that the voltage across the current detection resistor 104 is greater than the third preset voltage, that is, when the first switch tube 103 is likely to be broken down, the pulse width modulation module 107 can be used to control the first switch tube 103 to be in a cut-off state to achieve the purpose of power limitation and overcurrent protection.

[0034] In some embodiments, the third preset voltage is less than the second preset voltage, that is, when the first switch tube 103 is not broken down, the current discharge module 105 and the abnormal level detection module 109 will not be triggered, that is, the conduction state of the first switch 1051 and the second switch 1010 will not be switched, that is, the influence of the settings of the current discharge module 105 and the abnormal level detection module 109 on the charging process of the charger can be reduced, thereby improving the reliability of the charger.

[0035] In some embodiments, the charging protection circuit further includes a fuse 1012 , one end of the fuse 1012 is electrically connected to the power source 101 , and the other end of the fuse 1012 is electrically connected to the input end of the rectifier module 102 .

[0036] In some embodiments, if the AC voltage output by the power supply 101 is U1, the charging power of the charging device is P1, the impedance of the input power circuit of the charger is R, and the resistance of the current detection resistor 104 is R1, then under normal charging conditions, the current of the input power circuit is I1=P1 / U1, that is, the current in the path where the first switch tube 103 and the current detection resistor 104 are located is I1=P1 / U1.

[0037] For the charging protection circuit of a conventional charger, if the switch tube in the charging protection circuit fails and breaks down, that is, a short circuit occurs between the drain and source of the switch tube; at this time, no matter how the pulse width modulation module works, the switch tube is in a short-circuit state, and the charger's flyback circuit and transformer cannot normally transfer energy to the secondary side, that is, the charger's power circuit is equivalent to being short-circuited, so that the current flowing through the current detection resistor 104 will instantly increase from I1 to hundreds of times I2, at this time I2 = U1 / R; moreover, the transient power P = U1*R1 / R of the current detection resistor 104 is much greater than the current resistance or power consumption capability of the current detection resistor 104, resulting in the current detection resistor 104 being instantly open-circuited, and after the circuit is opened, the drain and source of the switch tube are in a short-circuited state, so the source of the switch tube is still in a high-voltage state, causing the pulse width modulation module and the current detection module to be broken down by high voltage, resulting in large-scale burning and carbonization of the charger.

[0038] In the present application, current clamping in a transient overcurrent scenario can be achieved by adding a current discharge module 105 and an abnormal level detection module 109 to the charging protection circuit. For example, the voltage clamping threshold of the current discharge module 105 can be set to V1, the threshold of the current detection module 1011 can be set to V2, and the voltage threshold of the abnormal level detection module 109 can be set to V3, that is, the first preset voltage is set to V1, the third preset voltage is set to V2, and the second preset voltage is set to V3, and V1>V3>V2.

[0039] During normal charging, the voltage upper limit across the current detection resistor 104 is V2. Thus, when the current detection module 1011 detects that the voltage across the current detection resistor 104 is V2, the pulse width modulation module 107 can be used to control the first switch tube 103 to be in the cut-off state, so as to achieve the purpose of power limitation and overcurrent protection.

[0040] When the first switch tube 103 is broken down and the current flowing through the current detection resistor 104 is instantly increased from I1 to I2, when the voltage across the current detection resistor 104 is greater than V1, that is, the current discharge module 105 triggers the threshold of V1, the first switch 1051 can be controlled to be in the on state, and the upper voltage limit across the current detection resistor 104 is clamped at V1; at this time, the excess current no longer passes through the current detection resistor 104, but passes through the path where the first switch 1051 is located to the ground; at this time, the power consumption across the current detection resistor 104 is always maintained at P2=V1*V1 / R1, and the current on the fuse 1012 is still very large and close to I2.

[0041] Since the upper voltage limit across the current detection resistor 104 is clamped at V1, and V1 > V3; thus, the abnormal level detection module 109 is triggered. The abnormal level detection module 109 can transmit an electrical signal to the driving module 1013 of the second switch 1010, and the driving module 1013 of the second switch 1010 controls the second switch 1010 to switch from the conducting state to the off state, so as to prevent the charger from being further damaged.

[0042] In some embodiments, if the fuse 1012 blows before the second switch 1010 has switched to the off state, that is, the blowing of the fuse 1012 realizes the disconnection between the charging protection circuit and the AC power supply, and can achieve the purpose of protecting the charger;

[0043] If the fuse 1012 does not blow after the second switch 1010 switches from the conducting state to the off state, that is, by switching the second switch 1010 to the off state, the electrical connection between the external AC power supply and the internal circuit of the charger can be cut off to prevent the charger from being further damaged.

[0044] Moreover, since the off state of the second switch 1010 can be actively controlled and belongs to a fuse - like open - circuit failure type device, it can avoid the popping sound generated when the fuse blows.

[0045] In some embodiments, the forward conduction property of the PN junction of a diode can be utilized. That is, the first switch 1051 can be set as a diode. For example, if the conduction voltage of the diode is VF, only need to make VF > V3 > V2. In this way, when the voltage across the current detection resistor 104 rises to I*R1 = VF, the diode conducts forward, and the voltage across the current detection resistor 104 can be clamped at VF. Similarly, current limitation can be achieved, and most of the current passes through the diode to the ground to prevent the current detection resistor 104 from failing.

[0046] In some embodiments, the first switch 1051 can be a single diode or multiple diodes connected in series.

[0047] For example, if the VF of a single diode is < V2 or V3, 2 or more diodes can be connected in series to achieve the purpose of n*VF > V3 > V2, so as to ensure that the current discharge module 105 does not trigger and become effective in normal application scenarios. When the current is abnormally transiently too large, current limitation is achieved through voltage clamping, and at the same time, the disconnection of the second switch 1010 or the fuse is used to achieve the protection purpose to protect the circuit.

[0048] In some embodiments, the above - mentioned first switching transistor 103 can be a MOS transistor, or a GaN transistor or a triode.

[0049] In some embodiments, the second switch tube 204 may be a MOS tube, or a GaN tube or a triode.

[0050] An embodiment of the present application also provides a charger, comprising the above-mentioned charging protection circuit.

[0051] It should be noted that the implementation method of the above-mentioned charging protection circuit embodiment is also applicable to the embodiment of the charger and can achieve the same technical effect, which will not be repeated here.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0053] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A charging protection circuit, characterized in that: include: A power supply, a rectifier module, a first switch tube, a current detection resistor and a current discharge module, wherein the rectifier module is used to convert the alternating current output by the power supply into direct current, the output end of the rectifier module is electrically connected to the first end of the current detection resistor through the first switch tube, and the second end of the current detection resistor is grounded, and the current discharge module includes a first switch, the input end of the first switch is electrically connected to the first end of the current detection resistor, and the output end of the first switch is electrically connected to the second end of the current detection resistor; Wherein, when the first switch tube is broken down, the first switch is in an on state.

2. The charging protection circuit according to claim 1, characterized in that: The current discharge module further includes a voltage detection unit and a control unit, and the control unit is electrically connected to the voltage detection unit and the first switch respectively; The voltage detection unit is used to detect the voltage across the current detection resistor; The control unit is used to control the first switch to be in an on state when the first switch tube is broken down and the voltage detection unit detects that the voltage across the current detection resistor is greater than a first preset voltage.

3. The charging protection circuit according to claim 2, characterized in that: The charging protection circuit further includes an abnormal level detection module and a second switch, wherein the abnormal level detection module is used to detect the voltage across the current detection resistor, and one end of the second switch is electrically connected to the power supply, and the other end is electrically connected to the input end of the rectifier module; When the abnormal level detection module detects that the voltage across the current detection resistor is greater than a second preset voltage, the second switch is controlled to switch from an on state to an off state, and the second preset voltage is less than the first preset voltage.

4. The charging protection circuit according to any one of claims 1 to 3, characterized in that: The resistance of the first switch is smaller than the resistance of the current detection resistor.

5. The charging protection circuit according to claim 2, characterized in that: The charging protection circuit further includes a pulse width modulation module and a current detection module, wherein the pulse width modulation module is electrically connected to the gate of the first switch tube, and the current detection module is used to detect the voltage across the current detection resistor, and the current detection module is also electrically connected to the pulse width modulation module; Wherein, when the current detection module detects that the voltage across the current detection resistor is greater than a third preset voltage, the pulse width modulation module is used to control the first switch tube to be in a cut-off state.

6. The charging protection circuit according to claim 3, characterized in that: The charging protection circuit also includes a fuse, one end of which is electrically connected to the power supply, and the other end of which is electrically connected to the input end of the rectifier module.

7. The charging protection circuit according to claim 2, characterized in that: The first switch is a diode.

8. The charging protection circuit according to claim 7, characterized in that: The conduction voltage of the diode is the first preset voltage.

9. The charging protection circuit according to claim 1, characterized in that: The first switch includes a plurality of diodes connected in series.

10. A charger, characterized in that: The invention comprises a charging protection circuit as claimed in any one of claims 1 to 9.

Images