CN204992533U - Switching power supply protection circuit, protection device and switching power supply - Google Patents
Switching power supply protection circuit, protection device and switching power supply Download PDFInfo
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- CN204992533U CN204992533U CN201520581475.4U CN201520581475U CN204992533U CN 204992533 U CN204992533 U CN 204992533U CN 201520581475 U CN201520581475 U CN 201520581475U CN 204992533 U CN204992533 U CN 204992533U
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- power supply
- switching power
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- protection element
- fuse
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Abstract
The utility model discloses a switching power supply protection circuit, protection device and switching power supply. The protection circuit include the overvoltage protection component, with overvoltage protection component connection's an over -current protection component and with overvoltage protection component connection's the 2nd over -current protection component, wherein, the overvoltage protection component connects in parallel between the live wire and zero line of power input end, an over -current protection component with the overvoltage protection component is parallelly connected, the 2nd over -current protection component with the overvoltage protection component is established ties, the 2nd over -current protection component is used for detecting the electric current increase of overvoltage protection component is broken off when just the temperature exceedes the settlement threshold value. The utility model discloses a corresponding switching power supply protection device and the switching power supply of providing still. The utility model provides a technical scheme can more effective protection switch power supply circuit.
Description
Technical Field
The utility model belongs to the technical field of the circuit, concretely relates to switching power supply protection circuit, protection device and switching power supply.
Background
Switching power supply circuits have found wide application in the field of power supply switching because their power transistors operate in a switched state. For a specific application, the output voltage of the switching power supply circuit is usually a fixed dc voltage, but the input voltage may have a certain variation. At the input of the switching power supply, a power surge voltage is generally generated. The surge, also called surge, is a transient overvoltage exceeding a normal voltage, and generally refers to a large current caused by a high voltage appearing in a circuit for a short time like "wave".
In the circuit of the prior art, as shown in fig. 1, a method for suppressing the surge voltage is to connect a common MOV (metal oxide varistor) in parallel between the L (live line) and the N (neutral line) of the input end of the power supply, and when the surge enters the power supply, the surge voltage is absorbed by the varistor MOV, thereby reducing the impact.
However, the prior art treatment method absorbs the surge voltage and also gives the MOV a certain damage (after N times of repeated work, the MOV itself has a life problem, the inner current of the MOV is increased continuously, the temperature inside the MOV is increased continuously, and finally, the phenomena of explosion, fire and the like may be caused.
Therefore, the conventional protection method for the switching power supply circuit is not perfect, and a safer protection method is desired.
Disclosure of Invention
The utility model aims to solve the technical problem that a switching power supply protection circuit, protection device and switching power supply are provided, can more effectively protect switching power supply circuit, guarantee user safety in utilization.
The utility model provides a technical scheme as follows:
the utility model provides a switching power supply protection circuit:
the protection circuit includes an overvoltage protection element, a first overcurrent protection element connected to the overvoltage protection element, and a second overcurrent protection element connected to the overvoltage protection element; wherein,
the overvoltage protection element is connected between a live wire and a zero line at the input end of the power supply in parallel;
the first overcurrent protection element is connected in parallel with the overvoltage protection element;
the second overcurrent protection element is connected with the overvoltage protection element in series, and the second overcurrent protection element is used for being disconnected when the current of the overvoltage protection element is increased and the temperature exceeds a set threshold value.
Preferably: the overvoltage protection element is a voltage dependent resistor, the first overcurrent protection element is a first fuse, and the second overcurrent protection element is a second fuse;
the piezoresistor is connected in parallel between the live wire and the zero line at the input end of the power supply;
the first fuse is connected with the piezoresistor in parallel;
the second fuse is connected with the piezoresistor in series and is used for detecting that the piezoresistor is disconnected when the current is increased and the temperature exceeds a set threshold value.
Preferably: the second fuse and the piezoresistor are sleeved by a sleeve.
Preferably: the protection circuit further comprises a rectifying circuit for converting alternating current into pulsating direct current;
one end of the first fuse is connected with one end of the rectifying circuit, and the other end of the first fuse is connected with one end of the piezoresistor;
and the other end of the piezoresistor is connected with the other end of the rectifying circuit.
Preferably: the second fuse is a high fusing temperature fuse and the piezoresistor is a high energy metal oxide piezoresistor.
Preferably: the sleeve is a heat-shrinkable sleeve.
The utility model also provides a switching power supply protection device contains above-mentioned switching power supply protection circuit.
The utility model also provides a switching power supply contains foretell switching power supply protection circuit.
Preferably: the switching power supply also comprises a first filter circuit, a charging capacitor, a PWM controller, an MOS (metal oxide semiconductor) tube, a transformer, a second rectifying circuit and a second filter circuit;
the first filter circuit is used for converting alternating current at the input end of the power supply into pulsating direct current after a rectifying circuit in the switching power supply protection circuit converts the alternating current into smooth direct current;
the charging capacitor is used for being connected with the first filter circuit and charging by using the smooth direct current output by the first filter circuit;
the PWM controller is used for being connected with the charging capacitor, and outputting a Pulse Width Modulation (PWM) signal to drive the MOS tube to be switched on and off after the voltage of the charging capacitor reaches the starting voltage of the PWM controller, so that the current passing through the transformer is changed into alternating current;
the MOS tube is used for being respectively connected with the PWM controller and the transformer and realizing the opening and closing according to the PWM signal output by the PWM controller;
the second rectifying circuit is used for being connected with the transformer and converting alternating current output by the transformer into pulsating direct current;
the second filter circuit is used for being connected with the second rectifying circuit and converting the pulsating direct current output by the second rectifying circuit into smooth direct current to supply power to a load.
Preferably: the transformer is used for generating alternating current, and the other path of alternating current generated by the transformer is converted into smooth direct current to supply power to the PWM controller after being sequentially subjected to rectification, current limiting and filtering.
According to the above technical solution, the utility model provides a switching power supply protection circuit, through increasing second overcurrent protection component (for example, the second fuse), establish ties second overcurrent protection component and overvoltage protection component (for example, piezo-resistor), so when overvoltage protection component's current increase and temperature exceeded the settlement threshold value, this second overcurrent protection component will automatic disconnection, thereby protected second overcurrent protection component (for example, piezo-resistor) can not because of the last explosion that leads to of inside constantly rising temperature, phenomenons such as catching fire, thereby effectively protected switching power supply circuit, user's safety in utilization has been protected.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
The invention will be further explained with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a prior art switching power supply circuit protection circuit;
fig. 2 is a schematic diagram of the protection circuit of the switching power supply of the present invention;
fig. 3 is a schematic diagram of the switching power supply circuit of the present invention;
fig. 4 is a schematic structural diagram of the switching power supply protection device of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
The utility model provides a switching power supply protection circuit, protection device and switching power supply can more effectively protect switching power supply circuit, protection user safety in utilization.
The following describes the present invention in detail with reference to the accompanying drawings.
Fig. 2 is a schematic diagram of the protection circuit of the switching power supply of the present invention. As shown in fig. 2, in the protection circuit for the input terminal of the switching power supply of the present invention, the control circuit is mainly composed of an overvoltage protection element, an overcurrent protection element connected to the overvoltage protection element, and a part of the peripheral circuit. The overvoltage protection element of the present invention may be a varistor but is not limited thereto, or may be another element having an overvoltage protection function, and the overcurrent protection element of the present invention may be a fuse (also referred to as a fuse) but is not limited thereto, or may be another element having an overcurrent protection function.
The utility model discloses a fuse, can be high fusing temperature fuse (also called high fusing temperature fuse) F, the utility model discloses a piezo-resistor can be high joule MOV (metal oxide varistor), and wherein joule is the unit of energy, and high joule MOV also is called high energy MOV.
Specifically, on the circuit shown in fig. 2, the utility model discloses increased high fusing temperature fuse F2 (specification parameter is 5A/250VT =130 ℃, represents maximum current 5A, maximum voltage 250V, maximum temperature 130 ℃), and entangle fuse F2 and piezo-resistor MOV with the sleeve pipe, stabilized. The sleeve may be, but is not limited to, a heat shrink sleeve, and may be other types of sleeves. In fig. 2, a voltage dependent resistor MOV is connected in parallel between the live line and the neutral line at the input of the power supply; a fuse F1 is connected in parallel with the piezoresistor; a fuse F2 is connected in series with the varistor MOV for opening when an increase in the current through the varistor MOV is detected and the temperature exceeds a set threshold. Also shown in fig. 2 is a bridge rectifier circuit consisting of diodes D1-D4 for converting alternating current to pulsating direct current. One end of a fuse F1 is connected with one end of the bridge rectifier circuit, and the other end of the fuse F1 is connected with one end of the MOV; the other end of the MOV is connected with the other end of the bridge rectifier circuit, and the MOV and the fuse F2 are sheathed by a heat-shrinkable sleeve.
Thus, when the MOV current is increased and the temperature is increased to a certain temperature due to heat generation, the fuse F2 will be fused, thereby cutting off the loop and ensuring that the MOV does not have potential safety hazards such as explosion or fire due to overheating. In the protection circuit of the prior art, when the MOV generates heat beyond a certain temperature, the fuse F1 is not disconnected, so that the safety hazards such as explosion or fire caused by overheating of the MOV cannot be avoided. Therefore, the utility model discloses circuit after the improvement not only to the more effective suppression of wave current voltage, makes the aspect of safety obtain better assurance moreover.
Fig. 3 is a schematic diagram of the switching power supply circuit of the present invention. The figure shows the structure of a relatively complete switching power supply circuit. As shown in fig. 3, the working flow of the circuit is:
firstly, the 100-240V (volt) AC power at the input end passes through the two surge protection elements of the fuse F1 and the MOV1, and then passes through the added fuse F2 and is applied to the D1-D4 (diode) bridge rectifier circuit. When the MOV heats and the temperature rises to a certain temperature threshold, F2 will be fused, thereby cutting off the loop and avoiding the potential safety hazard of explosion or fire caused by the MOV overheating. The certain temperature threshold may be empirically determined, and may be, for example, 130 ℃, but is not limited thereto, and may also be 120 ℃ or 140 ℃.
The alternating current is rectified by diodes D1-D4 of the rectifying circuit and then converted into pulsating direct current, and the pulsating direct current is filtered by three filter elements of a capacitor C1, an inductor L1 and a capacitor C3 of the filter circuit and then converted into smooth direct current. The smoothed direct current first charges a charging capacitor C4 via resistors R10, R11.
When the voltage ON the capacitor C4 reaches the start voltage of a PWM (pulse width modulation) controller U1, the PWM controller U1 starts, outputs a PWM signal through 6 pins, drives a Metal-Oxide-Semiconductor (MOS) transistor Q1 through a resistor network of R7 and R9 to turn ON and OFF (ON-OFF) the MOS transistor, so that the current passing through a transformer T1 is an alternating current, the alternating current generates an alternating magnetic field inside the transformer, a secondary coil induces the alternating magnetic field to generate an alternating current, the alternating current is rectified by a diode D7 or D8 to be converted into pulsating direct current, and then is filtered by capacitors C8 and C9 to be converted into smooth direct current to be output to supply power to a load.
In the other path, after the coil of the auxiliary winding induces an alternating magnetic field, alternating current is also generated and is converted into smooth direct current after being rectified by a diode D6, limited by a resistor R5 and filtered by a capacitor C4, and the smooth direct current is supplied to a PWM controller U1.
In addition, the combination of R16, R18, R15, C7, R12, R13, PC1 and C5 in the figure is a sampling voltage stabilizing circuit, and an error signal detected by the circuit is output to the No. 2 pin of U1, so that the switching frequency and the duty ratio of PWM are controlled, and the stability of output voltage is realized.
The OCP (over-current protection) function of the circuit in FIG. 3 is realized by protecting several elements R1, R2, Cx, R4, C2. When the current is too large, the voltage on R1\ R2 is too high, and the voltage signal is filtered by Cx, R4 and C2 and then applied to the 4 th pin of U1, so that U1 is controlled to stop outputting the PWM signal.
The combination of D5, R3, R6 and C6 in the circuit of FIG. 3 is a spike absorption circuit, which prevents the spike voltage of the D pole of Q1 from being too high to damage the MOS transistor.
Fig. 4 is a schematic structural diagram of the switching power supply protection device of the present invention. As shown in fig. 4, the switching power supply protection device 400 includes the above-mentioned switching power supply protection circuit 401, and the detailed description of the switching power supply protection circuit 401 refers to the foregoing description, which is not repeated herein.
To sum up, the utility model provides a switching power supply protection circuit, through increasing second overcurrent protection component (for example, the second fuse), establish ties second overcurrent protection component and overvoltage protection component (for example, piezo-resistor), so when overvoltage protection component's current increase and temperature exceeded the settlement threshold value, this second overcurrent protection component will automatic disconnection to protected second overcurrent protection component can not because of the inside explosion that constantly heaies up and finally leads to, phenomenons such as catching fire, thereby effectively protected switching power supply circuit, protected user's safety in utilization.
The technical solution provided by the embodiments of the present invention is described in detail above, and the principle and the implementation of the present invention are explained by applying specific examples herein, and the description of the above embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for the general technical personnel in the field, according to the idea of the present invention, there are changes in the specific implementation and application scope, to sum up, the content of the present specification should not be understood as the limitation of the present invention.
Claims (10)
1. A kind of switching power supply protective circuit, characterized by that:
the protection circuit includes an overvoltage protection element, a first overcurrent protection element connected to the overvoltage protection element, and a second overcurrent protection element connected to the overvoltage protection element; wherein,
the overvoltage protection element is connected between a live wire and a zero line at the input end of the power supply in parallel;
the first overcurrent protection element is connected in parallel with the overvoltage protection element;
the second overcurrent protection element is connected with the overvoltage protection element in series, and the second overcurrent protection element is used for being disconnected when the current of the overvoltage protection element is increased and the temperature exceeds a set threshold value.
2. The switching power supply protection circuit according to claim 1, wherein:
the overvoltage protection element is a voltage dependent resistor, the first overcurrent protection element is a first fuse, and the second overcurrent protection element is a second fuse;
the piezoresistor is connected in parallel between the live wire and the zero line at the input end of the power supply;
the first fuse is connected with the piezoresistor in parallel;
the second fuse is connected with the piezoresistor in series and is used for detecting that the piezoresistor is disconnected when the current is increased and the temperature exceeds a set threshold value.
3. The switching power supply protection circuit according to claim 2, wherein:
the second fuse and the piezoresistor are sleeved by a sleeve.
4. The switching power supply protection circuit according to claim 2 or 3, wherein:
the protection circuit further comprises a rectifying circuit for converting alternating current into pulsating direct current;
one end of the first fuse is connected with one end of the rectifying circuit, and the other end of the first fuse is connected with one end of the piezoresistor;
and the other end of the piezoresistor is connected with the other end of the rectifying circuit.
5. The switching power supply protection circuit according to claim 2 or 3, wherein:
the second fuse is a high fusing temperature fuse and the piezoresistor is a high energy metal oxide piezoresistor.
6. The switching power supply protection circuit according to claim 3, wherein:
the sleeve is a heat-shrinkable sleeve.
7. A switching power supply protection device comprising the switching power supply protection circuit according to any one of claims 1 to 6.
8. A switching power supply comprising the switching power supply protection circuit according to any one of claims 1 to 6.
9. The switching power supply according to claim 8, wherein:
the switching power supply also comprises a first filter circuit, a charging capacitor, a Pulse Width Modulation (PWM) controller, a Metal Oxide Semiconductor (MOS) transistor, a transformer, a second rectifying circuit and a second filter circuit;
the first filter circuit is used for converting alternating current at the input end of the power supply into pulsating direct current after a rectifying circuit in the switching power supply protection circuit converts the alternating current into smooth direct current;
the charging capacitor is used for being connected with the first filter circuit and charging by using the smooth direct current output by the first filter circuit;
the PWM controller is used for being connected with the charging capacitor, and outputting a Pulse Width Modulation (PWM) signal to drive the MOS tube to be switched on and off after the voltage of the charging capacitor reaches the starting voltage of the PWM controller, so that the current passing through the transformer is changed into alternating current;
the MOS tube is used for being respectively connected with the PWM controller and the transformer and realizing the opening and closing according to the PWM signal output by the PWM controller;
the second rectifying circuit is used for being connected with the transformer and converting alternating current output by the transformer into pulsating direct current;
the second filter circuit is used for being connected with the second rectifying circuit and converting the pulsating direct current output by the second rectifying circuit into smooth direct current to supply power to a load.
10. The switching power supply according to claim 9, wherein:
the transformer is used for generating alternating current, and the other path of alternating current generated by the transformer is converted into smooth direct current to supply power to the PWM controller after being sequentially subjected to rectification, current limiting and filtering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520581475.4U CN204992533U (en) | 2015-08-05 | 2015-08-05 | Switching power supply protection circuit, protection device and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520581475.4U CN204992533U (en) | 2015-08-05 | 2015-08-05 | Switching power supply protection circuit, protection device and switching power supply |
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| Publication Number | Publication Date |
|---|---|
| CN204992533U true CN204992533U (en) | 2016-01-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520581475.4U Expired - Fee Related CN204992533U (en) | 2015-08-05 | 2015-08-05 | Switching power supply protection circuit, protection device and switching power supply |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106451350A (en) * | 2015-08-05 | 2017-02-22 | 惠州市忠邦电子有限公司 | Switching power supply protection circuit and device and switching power supply |
| CN111854071A (en) * | 2020-06-09 | 2020-10-30 | 海信（山东）空调有限公司 | Switch input circuit and air conditioner |
-
2015
- 2015-08-05 CN CN201520581475.4U patent/CN204992533U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106451350A (en) * | 2015-08-05 | 2017-02-22 | 惠州市忠邦电子有限公司 | Switching power supply protection circuit and device and switching power supply |
| CN111854071A (en) * | 2020-06-09 | 2020-10-30 | 海信（山东）空调有限公司 | Switch input circuit and air conditioner |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160120 |