CN102496906A - Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof - Google Patents

Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof Download PDF

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Publication number
CN102496906A
CN102496906A CN2011104470337A CN201110447033A CN102496906A CN 102496906 A CN102496906 A CN 102496906A CN 2011104470337 A CN2011104470337 A CN 2011104470337A CN 201110447033 A CN201110447033 A CN 201110447033A CN 102496906 A CN102496906 A CN 102496906A
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circuit
power supply
voltage
filter capacitor
output filter
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CN2011104470337A
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Chinese (zh)
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庄锦清
王星光
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TPV Electronics Fujian Co Ltd
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TPV Electronics Fujian Co Ltd
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Priority to CN2011104470337A priority Critical patent/CN102496906A/en
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Abstract

The invention relates to the display device overvoltage protection technology field, especially to a method of overvoltage protection of a PFC output filter capacitor of a liquid crystal display device and an overvoltage protection circuit thereof. The method is characterized in that: a negative voltage of an auxiliary winding of an auxiliary power supply of a display device is detected, so that voltages at two ends of a PFC output filter capacitor are determined; and it is ensured that power supply circuits of a main load power controller and a PFC controller of the display device are cut off before overvoltage of the PFC output filter capacitor. According to the invention, overvoltage-resistant capability of a circuit can be effectively improved; a market reject ratio of a display product can be reduced; and the product reliability can be improved.

Description

The method and the circuit of the PFC output filter capacitor overvoltage protection of display unit
Technical field
The present invention relates to the method and 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 this invention is to provide a kind of method of PFC output filter capacitor overvoltage protection of display unit, can effectively improve the anti-overvoltage capabilities of circuit, reduce the market fraction defective that shows product, improve product reliability.
Method of the present invention adopts following scheme to realize: a kind of method of PFC output filter capacitor overvoltage protection of display unit; It is characterized in that: the negative voltage of the auxiliary winding 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 pfc controller are turn-offed.
In an embodiment of the present invention; One overpressure treatment circuit is provided; This overpressure treatment circuit comprises voltage detecting circuit, comparison circuit and executive circuit; Described voltage detecting circuit is used for described detecting, and this voltage detecting circuit is controlled the open and close of said power supply circuits after the magnitude of voltage of gathering is compared through executive circuit.
Another object of the present invention provides a kind of PFC output filter capacitor overvoltage crowbar of display unit, has PFC output filter capacitor overvoltage protection.
Overvoltage crowbar of the present invention 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: 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 an embodiment of the present invention; Described voltage detecting circuit is made up of resistance R 9315, diode D9305, capacitor C 9312 and resistance R 9316; Said diode D9305 and capacitor C 9312 are formed the current rectifying and wave filtering circuit of said auxiliary winding negative voltage; Said resistance R 9315 is formed the RC filter with capacitor C 9312; Being used for the higher-order of oscillation that the auxiliary winding leakage inductance of filtering causes disturbs; Said resistance R 9316 can equal the voltage at capacitor C 9312 two ends
Figure 2011104470337100002DEST_PATH_IMAGE002
as the bleeder resistance of capacitor C 9312 in real time, and wherein Na representes the number of turn of auxiliary winding; Np representes the number of turn of said accessory power supply primary coil, and V_bulk representes the voltage at PFC output filter capacitor two ends.
In an embodiment of the present invention, 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 an embodiment of the present invention, described display unit is LCD or LCD TV.
The present invention confirms 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 a circuit system theory diagram of the present invention.
Fig. 2 is that the circuit of the embodiment of the invention connects sketch map.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is further specified.
Present embodiment provides a kind of method of PFC output filter capacitor overvoltage protection of display unit; It is characterized in that: the negative voltage of the auxiliary winding 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 pfc controller are turn-offed.
In the present embodiment; One overpressure treatment circuit is provided; Realize that this overpressure treatment circuit comprises voltage detecting circuit, comparison circuit and executive circuit to the detection and the execution of auxiliary winding negative voltage side, described voltage detecting circuit is used for described detecting; This voltage detecting circuit is controlled the open and close of said power supply circuits after the magnitude of voltage of gathering is compared through executive circuit.
Concrete; See also Fig. 1, Fig. 1 is the circuit system theory diagram of present embodiment, and we can know from figure; This circuit comprises the accessory power supply of this display unit and is the power supply circuits of the main load power source controller of this display unit and pfc controller power supply; The output of pfc controller circuit is connected with described accessory power supply, and 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 embodiment of the invention connects sketch map; In order to let those skilled in the art better understand the present invention, 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:
Figure 2011104470337100002DEST_PATH_IMAGE004
.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
Figure DEST_PATH_IMAGE002A
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 display unit of the present invention can be a LCD, also can be LCD TV.
The above is merely preferred embodiment of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.

Claims (6)

1. the method for the PFC output filter capacitor overvoltage protection of a display unit; It is characterized in that: the negative voltage of the auxiliary winding 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 pfc controller are turn-offed.
2. the method for the PFC output filter capacitor overvoltage protection of display unit according to claim 1; It is characterized in that: an overpressure treatment circuit is provided; This overpressure treatment circuit comprises voltage detecting circuit, comparison circuit and executive circuit; Described voltage detecting circuit is used for described detecting, and this voltage detecting circuit is controlled the open and close of said power supply circuits after the magnitude of voltage of gathering is compared through executive circuit.
3. 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.
4. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 3; It is characterized in that: described voltage detecting circuit is made up of resistance R 9315, diode D9305, capacitor C 9312 and resistance R 9316; Said diode D9305 and capacitor C 9312 are formed the current rectifying and wave filtering circuit of said auxiliary winding negative voltage; Said resistance R 9315 is formed the RC filter with capacitor C 9312; Being used for the higher-order of oscillation that the auxiliary winding leakage inductance of filtering causes disturbs; Said resistance R 9316 is as the bleeder resistance of capacitor C 9312; The voltage at capacitor C 9312 two ends can be equaled in real time
Figure 2011104470337100001DEST_PATH_IMAGE002
; Wherein Na representes the number of turn of auxiliary winding, and Np representes the number of turn of said accessory power supply primary coil, and V_bulk representes the voltage at PFC output filter capacitor two ends.
5. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 3; 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.
6. the PFC output filter capacitor overvoltage crowbar of display unit according to claim 3, it is characterized in that: described display unit is LCD or LCD TV.
CN2011104470337A 2011-12-28 2011-12-28 Method of overvoltage protection of PFC output filter capacitor of display device and overvoltage protection circuit thereof Pending CN102496906A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015117392A1 (en) * 2014-08-19 2015-08-13 中兴通讯股份有限公司 Method and device for improving digital pfc circuit reliability
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
CN105811776A (en) * 2016-03-16 2016-07-27 阳光电源股份有限公司 Switching power supply circuit
CN109727564A (en) * 2019-03-07 2019-05-07 青岛海信电器股份有限公司 Display device and Zenith tracking method
CN110880294A (en) * 2019-12-10 2020-03-13 深圳创维-Rgb电子有限公司 OLED driving power supply and electronic product

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JP2005198469A (en) * 2004-01-09 2005-07-21 Sharp Corp Switching power supply unit
CN1728491A (en) * 2004-07-30 2006-02-01 松下电器产业株式会社 Power source protector
CN1801564A (en) * 2005-01-08 2006-07-12 艾默生网络能源系统有限公司 Switch power supply with overvoltage protection and its overvoltage protection method
CN202405744U (en) * 2011-12-28 2012-08-29 福建捷联电子有限公司 Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1517824A (en) * 2003-01-09 2004-08-04 ���ǵ�����ʽ���� Power-supply device and its control method
JP2005198469A (en) * 2004-01-09 2005-07-21 Sharp Corp Switching power supply unit
CN1728491A (en) * 2004-07-30 2006-02-01 松下电器产业株式会社 Power source protector
CN1801564A (en) * 2005-01-08 2006-07-12 艾默生网络能源系统有限公司 Switch power supply with overvoltage protection and its overvoltage protection method
CN202405744U (en) * 2011-12-28 2012-08-29 福建捷联电子有限公司 Overvoltage protection circuit for power factor correction (PFC) output filter capacitor of display device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015117392A1 (en) * 2014-08-19 2015-08-13 中兴通讯股份有限公司 Method and device for improving digital pfc circuit reliability
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
CN105811776A (en) * 2016-03-16 2016-07-27 阳光电源股份有限公司 Switching power supply circuit
CN109727564A (en) * 2019-03-07 2019-05-07 青岛海信电器股份有限公司 Display device and Zenith tracking method
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
CN110880294A (en) * 2019-12-10 2020-03-13 深圳创维-Rgb电子有限公司 OLED driving power supply and electronic product

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Application publication date: 20120613