CN202405744U - Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device - Google Patents
Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device Download PDFInfo
- Publication number
- CN202405744U CN202405744U CN2011205584114U CN201120558411U CN202405744U CN 202405744 U CN202405744 U CN 202405744U CN 2011205584114 U CN2011205584114 U CN 2011205584114U CN 201120558411 U CN201120558411 U CN 201120558411U CN 202405744 U CN202405744 U CN 202405744U
- Authority
- CN
- China
- Prior art keywords
- circuit
- power supply
- filter capacitor
- pfc
- output filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Dc-Dc Converters (AREA)
Abstract
The utility model relates to an overvoltage protection circuit for a PFC output filter capacitor of a display device. The overvoltage protection circuit comprises an auxiliary power supply of the display device and a power supply circuit for supplying a main load power controller and a PFC controller of the display device. The overvoltage protection circuit is characterized in that the overvoltage protection circuit further comprises an overvoltage processing circuit which comprises a voltage detection circuit, a comparison circuit and an executive circuit, wherein a detecting end of the voltage detection circuit is connected with a negative voltage end of an auxiliary winding of the auxiliary power supply, the comparison circuit compares voltage values collected by the voltage detection circuit, and the executive circuit controls the on and off of the power supply circuit. According to the overvoltage protection circuit for the PFC output filter capacitor of the display device, the overvoltage-resistant capacity of circuits can be effectively improved, the reject rate of display products in the market can be reduced, and the reliability of the products can be improved.
Description
Technical field
The utility model relates to the circuit of the PFC output filter capacitor overvoltage protection in display unit over-voltage protection technology field, particularly a kind of liquid crystal indicator.
Background technology
Present LCD TV power supply generally is made up of following module: power factor (PF) emphasizer circuit, auxiliary power circuit, main electric power circuit.AC-input voltage arrives direct current 390V to 400V through power factor correction circuit with boost in voltage again after the rectifier bridge rectification, resupply auxiliary power circuit and main electric power circuit.Active PFC (PFC) circuit output filter capacitor is generally selected the withstand voltage of 450V, and the anti-surge voltage of this electric capacity is up to 500V.
Present LCD TV power supply is not to PFC output filter capacitor design excess voltage protection.In the electrical network owing to the reasons such as variation of load; Have various Surge voltage, this Surge voltage possibly be charged to higher voltage with the PFC output filter capacitor, exceeds the proof voltage that electric capacity can bear; Thereby cause condenser failure, so the fraction defective of this electric capacity is high on the market.
Summary of the invention
In view of this, the purpose of the utility model provides a kind of PFC output filter capacitor overvoltage crowbar of display unit, has PFC output filter capacitor overvoltage protection.
The overvoltage crowbar of the utility model adopts following scheme to realize: a kind of PFC output filter capacitor overvoltage crowbar of display unit; Comprise the accessory power supply of this display unit and be the power supply circuits of the main load power source controller of this display unit and pfc controller power supply; It is characterized in that: also comprise an overpressure treatment circuit, this overpressure treatment circuit comprises a voltage detecting circuit, a comparison circuit and an executive circuit; The test side of described voltage detecting circuit is connected with the negative pressure end of the auxiliary winding of said accessory power supply; The magnitude of voltage that said comparison circuit is gathered said voltage detecting circuit is controlled the shutoff of said power supply circuits through relatively through executive circuit.
In the utility model one embodiment, described voltage detecting circuit comprises: one first resistance, and the one of which end is connected with the negative pressure end of said auxiliary winding; One diode, its negative pole is connected with the other end of said first resistance, and its positive pole is connected with the input of described comparison circuit; One electric capacity, the one of which end is connected with the positive pole of said diode, another termination power ground; And one second resistance, the one of which end is connected with the positive pole of said diode, another termination power ground.
In the utility model one embodiment, the switch of said power supply circuits is to realize through an optical coupled switch, and described executive circuit is through dragging down the output of this optocoupler, to realize cutting out of optocoupler.
In the utility model one embodiment, described display unit is LCD or LCD TV.
The utility model is confirmed the voltage at PFC output filter capacitor two ends through the negative voltage of the auxiliary winding of detecting accessory power supply.Before PFC output filter capacitor overvoltage, turn off with pfc circuit and to the power circuit of basic load power supply; Make PFC output filter capacitor ripple current when the overvoltage electricity very little; Have only accessory power supply to eat and carry, thereby the loss that ripple current is caused reduces greatly.Add the leakage current loss and the total loss of PFC output filter capacitor equals the ripple current loss,, just can bear bigger overvoltage so the PFC output filter capacitor can bear bigger leakage current loss.Improved the anti-overvoltage capabilities of integrated circuit like this.The loss of this method for detecting is very little, in 20mW, meets strict standby efficiency standard easily.
Description of drawings
Fig. 1 is the utility model circuit system theory diagram.
Fig. 2 is that the circuit of the utility model embodiment connects sketch map.
Embodiment
Below in conjunction with accompanying drawing and embodiment the utility model is further specified.
See also Fig. 1; Fig. 1 is the circuit system theory diagram of present embodiment; We can know from figure, and this circuit comprises the accessory power supply of this display unit and the power supply circuits of supplying power for the main load power source controller of this display unit and pfc controller, and the output of pfc controller circuit is connected with described accessory power supply; The output of this accessory power supply is through secondary commutation filter circuit output 5V power supply; In addition, the utility model is on the basis of this connecting circuit, also further to comprise an overpressure treatment circuit, and this overpressure treatment circuit comprises a voltage detecting circuit, a comparison circuit and an executive circuit; The test side of described voltage detecting circuit is connected with the negative pressure end of the auxiliary winding of said accessory power supply; The magnitude of voltage that said comparison circuit is gathered said voltage detecting circuit is controlled the shutoff of said power supply circuits through relatively through executive circuit.Please continue with reference to Fig. 1; In the present embodiment; Also comprise a standby power output voltage detecting circuit in the native system circuit, this standby power output voltage detecting circuit detects this out-put supply, and is connected with the interior standby power control circuit of accessory power supply through feedback circuit.
Please with reference to Fig. 2; Fig. 2 is that the circuit of the utility model embodiment connects sketch map; In order to let those skilled in the art better understand the utility model, each module is distinguished with empty frame among Fig. 2, the overpressure treatment circuit comprises voltage detecting circuit, comparison circuit and executive circuit among the figure; Below we specify each circuit:
(1) voltage detecting circuit:
If the number of primary turns of T9301 is Np; The number of turn of auxiliary winding is Na; PFC output voltage (being PFC output filter capacitor voltage) is V_bulk; The negative voltage of the auxiliary winding of T9301 is V_a_negative, then:
.So,, just can confirm the voltage at PFC output filter capacitor two ends as long as detect the negative voltage of the auxiliary winding of T9301.
This voltage detecting circuit is by R9315, D9305, and C9312 and R9316 form.D9305 and C9312 form the current rectifying and wave filtering circuit of the negative voltage of auxiliary winding; R9315 and C9312 form the RC filter; Being used for the higher-order of oscillation that the auxiliary winding leakage inductance of filtering causes disturbs; R9316 can equal the voltage at C9312 two ends
as the bleeder resistance of capacitor C 9312 in real time.
(2) comparison circuit:
This comparison circuit is by ZD9302, ZD9303, and ZD9304, Q9364, R9317, R9318, C9313 forms.The voltage at C9312 two ends deducts ZD9302, ZD9303, the voltage stabilizing value of three series connection of ZD9304 voltage stabilizing didoe; Grid source electrode threshold voltage Vgs (th) with Q9364 compares again; If greater than the grid source electrode threshold voltage Vgs (th) of Q9364, then Q9364 conducting, its drain voltage drags down; If less than the grid source electrode threshold voltage Vgs (th) of Q9364, then Q9364 ends.R9317 is the driving resistor of Q9364, and R9318 is as the pull-up resistor of Q9364, and C9313 is used for the interference of filtering Noise, avoids false triggering.
(3) executive circuit:
In the present embodiment, this executive circuit is through dragging down the output of this optocoupler, to realize cutting out of optocoupler.Executive circuit is by R9322, Q9365, and R9320, R9321, Q9366, R9319, D9306 forms.If C9312 detects the electric voltage over press of PFC filter capacitor, then Q9364 leads saturation conduction, and the Q9364 drain voltage drags down; Q9365 ends, the Q9366 saturation conduction, and the Q9366 drain voltage drags down; Meanwhile, the D9306 conducting drags down the end of the connection optocoupler IC9304 of R9314; Then Q9301 ends, and the voltage of giving main load power source controller, pfc controller power supply of auxiliary winding turn-offs, and pfc circuit and main load power source circuit quit work.Thereby the ripple current of PFC output filter filter electric capacity reduces greatly.Otherwise if the voltage at PFC filter capacitor two ends does not have overvoltage, then Q9364 ends, the Q9365 saturation conduction, and Q9366 ends, and D9306 ends.Do not influence the operate as normal of other circuit.
What deserves to be mentioned is that the described display unit of the utility model can be a LCD, also can be LCD TV.
The negative voltage of the auxiliary winding of the utility model through detecting this display unit accessory power supply is confirmed the voltage at PFC output filter capacitor two ends; Guaranteed before PFC output filter capacitor overvoltage, the main load power source controller of this display unit and the power supply circuits of FPC controller are turn-offed.Circuit structure is simple, can effectively reduce the fraction defective of product.
The above is merely the preferred embodiment of the utility model, and all equalizations of being done according to the utility model claim change and modify, and all should belong to the covering scope of the utility model.
Claims (4)
1. the PFC output filter capacitor overvoltage crowbar of a display unit; Comprise the accessory power supply of this display unit and be the power supply circuits of the main load power source controller of this display unit and pfc controller power supply; It is characterized in that: also comprise an overpressure treatment circuit, this overpressure treatment circuit comprises a voltage detecting circuit, a comparison circuit and an executive circuit; The test side of described voltage detecting circuit is connected with the negative pressure end of the auxiliary winding of said accessory power supply; The magnitude of voltage that said comparison circuit is gathered said voltage detecting circuit is controlled the shutoff of said power supply circuits through relatively through executive circuit.
2. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 1 is characterized in that described voltage detecting circuit comprises:
One first resistance, the one of which end is connected with the negative pressure end of said auxiliary winding;
One diode, its negative pole is connected with the other end of said first resistance, and its positive pole is connected with the input of described comparison circuit;
One electric capacity, the one of which end is connected with the positive pole of said diode, another termination power ground; And
One second resistance, the one of which end is connected with the positive pole of said diode, another termination power ground.
3. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 1; It is characterized in that: the switch of said power supply circuits is to realize through an optical coupled switch; Described executive circuit is through dragging down the output of this optocoupler, to realize cutting out of optocoupler.
4. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 1, it is characterized in that: described display unit is LCD or LCD TV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011205584114U CN202405744U (en) | 2011-12-28 | 2011-12-28 | Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011205584114U CN202405744U (en) | 2011-12-28 | 2011-12-28 | Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202405744U true CN202405744U (en) | 2012-08-29 |
Family
ID=46703361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011205584114U Expired - Fee Related CN202405744U (en) | 2011-12-28 | 2011-12-28 | Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202405744U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102496906A (en) * | 2011-12-28 | 2012-06-13 | 福建捷联电子有限公司 | Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof |
| CN105571044A (en) * | 2014-10-09 | 2016-05-11 | 青岛海尔空调电子有限公司 | Control method for variable frequency air conditioner |
| WO2020177399A1 (en) * | 2019-03-07 | 2020-09-10 | 青岛海信电器股份有限公司 | Display apparatus and overvoltage detection method |
-
2011
- 2011-12-28 CN CN2011205584114U patent/CN202405744U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102496906A (en) * | 2011-12-28 | 2012-06-13 | 福建捷联电子有限公司 | Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof |
| CN105571044A (en) * | 2014-10-09 | 2016-05-11 | 青岛海尔空调电子有限公司 | Control method for variable frequency air conditioner |
| WO2020177399A1 (en) * | 2019-03-07 | 2020-09-10 | 青岛海信电器股份有限公司 | Display apparatus and overvoltage detection method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109412117A (en) | A kind of protection circuit against input over-voltage | |
| CN108206517A (en) | A kind of low cost inputs anti-overvoltage crowbar | |
| CN103545803A (en) | Protective device of equipment power source interface circuit | |
| US20120020131A1 (en) | Power apparatus and method of supplying power | |
| CN102496906A (en) | Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof | |
| CN103219893A (en) | Switch power supply controller and switch power supply circuit | |
| CN202405744U (en) | Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device | |
| CN203788153U (en) | Over-power compensation circuit of flyback power supply | |
| CN111193317A (en) | Power-down protection circuit for terminal equipment | |
| CN202750021U (en) | Converter for converting alternating current into direct current | |
| CN204993097U (en) | Turn over and swash formula alternately load regulation switching power supply and TV | |
| CN205039513U (en) | High -power circuit protector against power failure of high efficiency | |
| CN203233312U (en) | Switch power supply controller and switch power supply device | |
| CN202696482U (en) | Power supply circuit for leakage circuit breaker | |
| CN202889180U (en) | AC (Alternating Current) and DC (Direct Current) input self-adaptive circuit | |
| CN201937238U (en) | Input undervoltage protection circuit | |
| CN201536324U (en) | Capacitance-resistance voltage reduction circuit and apparatus | |
| CN204316323U (en) | A kind of SS (soft start) control circuit | |
| CN103472354A (en) | Switching-closing judging circuit of electric leakage reclosure breaker | |
| CN102983736A (en) | AC-DC switch power source having power factor correcting function | |
| CN206977324U (en) | Power circuit for low-voltage circuit breaker | |
| CN104218790B (en) | DC voltage stabilization circuit with soft start and lamp | |
| CN205945018U (en) | Dropout protection circuit that resistance -capacitance pressure reducing type is under -voltage | |
| CN202135070U (en) | Dual-voltage capacitance-resistance voltage-reduction energy saving circuit | |
| CN203616387U (en) | Single-phase electric energy meter with special-purpose power supply |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120829 Termination date: 20141228 |
|
| EXPY | Termination of patent right or utility model |