CN215379291U - Harmonic improved LED drive circuit - Google Patents

Harmonic improved LED drive circuit Download PDF

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Publication number
CN215379291U
CN215379291U CN202023083261.4U CN202023083261U CN215379291U CN 215379291 U CN215379291 U CN 215379291U CN 202023083261 U CN202023083261 U CN 202023083261U CN 215379291 U CN215379291 U CN 215379291U
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resistor
electrically connected
capacitor
transformer
diode
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CN202023083261.4U
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肖俊承
王一龙
张铁镭
石从怀
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Foshan Yigeer Electronics Co ltd
Eaglerise Electric and Electronic China Co Ltd
Jian Eaglerise Electric Co Ltd
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Foshan Yigeer Electronics Co ltd
Eaglerise Electric and Electronic China Co Ltd
Jian Eaglerise Electric Co Ltd
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Priority to CN202023083261.4U priority Critical patent/CN215379291U/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The utility model discloses an LED drive circuit with improved harmonic waves, which comprises a bridge rectifier unit, an RCD harmonic wave improving unit and an isolation flyback unit, wherein the input end of the RCD harmonic wave improving unit is electrically connected with the direct current output end of the bridge rectifier unit, and the output end of the RCD harmonic wave improving unit is electrically connected with the input end of the isolation flyback unit; the RCD harmonic wave improving unit comprises a resistor R1, a diode D1, a non-polar capacitor CB1 and a polar capacitor EC1, and the isolation flyback unit comprises an input module, a transformer T1, an output module and a drive control module. The LED drive circuit with improved harmonic can filter the input rectified alternating current, can improve the PF value, reduce THD, improve the harmonic, and meet IEC 61000-3-2: 2018. The polar capacitor EC1 is used for filtering, so that power frequency ripples can be removed, the isolation flyback unit at the rear end is not interfered by the power frequency ripples, and the output to a load (an LED lamp and the like) is free of stroboflash and meets the lighting standard.

Description

Harmonic improved LED drive circuit
Technical Field
The utility model relates to the field of LED driving circuits, in particular to an LED driving circuit with improved harmonic waves.
Background
The LED lamp has the advantages of low power consumption, long service life, fast reaction speed, high efficiency, energy saving, etc., and has been increasingly widely used. At present, the power supply mode of the LED lamp mostly adopts direct current, the commercial power of the power supply needs to be converted into direct current through a rectifier bridge, then the LED lamp beads are driven by a driving circuit to emit light, and the input part of the LED lamp beads generally consists of a bridge rectifier and a filter capacitor. However, most of the filtering performance of the existing LED driving circuit can not reach the 5 th edition standard IEC 61000-3-2 of harmonic current emission: 2018, the LED driving circuit still has power frequency ripples, so that the LED lamp has a stroboscopic condition.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide an LED drive circuit with improved harmonic waves, which achieves the purposes that the harmonic current emits the standard IEC 61000-3-2 of 5 th edition: 2018, can remove power frequency ripples, avoid stroboscopic conditions, and meet lighting standards.
In order to achieve the purpose, the utility model adopts the following technical scheme:
an LED drive circuit with improved harmonic waves comprises a bridge rectifier unit, an RCD harmonic wave improving unit and an isolation flyback unit, wherein the input end of the RCD harmonic wave improving unit is electrically connected with the direct current output end of the bridge rectifier unit, and the output end of the RCD harmonic wave improving unit is electrically connected with the input end of the isolation flyback unit;
the RCD harmonic wave improving unit comprises a resistor R1, a diode D1, a nonpolar capacitor CB1 and a polar capacitor EC1, the isolation flyback unit comprises an input module, a transformer T1, an output module and a drive control module, one end of the resistor R1, the cathode of the diode D1, one end of the nonpolar capacitor CB1 and the input end of the input module are electrically connected with the direct current output end of the bridge rectifier unit, the anode of the diode D1 and the other end of the resistor R1 are electrically connected with the anode of the polar capacitor EC1, and the other end of the nonpolar capacitor CB1 and the cathode of the polar capacitor EC1 are grounded;
the output end of the input module is electrically connected with the primary winding of the transformer T1, the drive control module comprises an LED drive chip U1 and an MOS tube Q1, the power input end of the LED drive chip U1 is electrically connected with the output end of the RCD harmonic wave improvement unit, the G pole of the MOS tube Q1 is electrically connected with the output end of the LED drive chip U1, the D pole of the MOS tube Q1 is electrically connected with the primary winding of the transformer T1, and the S pole of the MOS tube Q1 is grounded;
the output module comprises a diode D3 and a polarity capacitor EC4, the anode of the diode D3 is electrically connected with the same-name end of the secondary winding of the transformer T1, the cathode of the diode D3 is electrically connected with the anode of the polarity capacitor EC4, and the cathode of the polarity capacitor EC4 is electrically connected with the non-same-name end of the secondary winding of the transformer T1.
Preferably, the model of the LED driving chip U1 is OB 3398.
Preferably, the isolated flyback unit further includes a chip start module, the chip start module includes resistors R10, R11, R28, a jumper resistor R01, a diode D2, a non-polar capacitor C5 and a polar capacitor EC3, one end of the resistor R10 is electrically connected to one end of the non-polar capacitor CB1, the other end of the resistor R10 is electrically connected to one end of the resistor R11, the other end of the resistor R11 and the negative electrode of the diode D2 are both electrically connected to one end of the jumper resistor R01, the positive electrode of the diode D2 is electrically connected to one end of the resistor R28, the other end of the resistor R28 is electrically connected to the dotted end of the auxiliary winding of the transformer T1, the non-dotted end of the auxiliary winding of the transformer T1 is grounded, and the auxiliary winding of the transformer T1 is connected to the same-side winding;
the other end of the jumper resistor R01, one end of the nonpolar capacitor C5 and the positive electrode of the polar capacitor EC3 are electrically connected with the VDD end of the LED driving chip U1, and the other end of the nonpolar capacitor C5, the negative electrode of the polar capacitor EC3 and the GND end of the LED driving chip U1 are all grounded.
Preferably, the chip starting module further includes resistors R15, R16, R26 and nonpolar capacitors C1, C4, one end of the resistor R15 is electrically connected to the same-name end of the auxiliary winding of the transformer T1, the other end of the resistor R15, one end of the resistor R16, one end of the resistor R26, and one end of the nonpolar capacitor C4 are all electrically connected to the INV end of the LED driving chip U1, one end of the nonpolar capacitor C1 is electrically connected to the COMP end of the LED driving chip U1, and the other end of the resistor R16, the other end of the resistor R26, the other end of the nonpolar capacitor C4, and the other end of the nonpolar capacitor C1 are all grounded.
Preferably, the input module includes resistors R6, R7, R13, a diode D1 and a non-polar capacitor C2, one end of the resistor R6, one end of the resistor R7, one end of the resistor R13, one end of the non-polar capacitor C2 and one end of the non-polar capacitor CB1 are all electrically connected to the same-name end of the primary winding of the transformer T1, an anode of the diode D1 is electrically connected to the non-same-name end of the primary winding, and the other end of the resistor R6, the other end of the resistor R7, the other end of the resistor R13 and the other end of the non-polar capacitor C2 are all electrically connected to a cathode of the diode D1.
Preferably, the isolated flyback unit further includes an output current control module, the S-pole of the MOS transistor Q1 is grounded through the output current control module, the output current control module includes resistors R17, R18, R19, R20, R29, R30 and a nonpolar capacitor C3, one end of the resistor R17, one end of the nonpolar capacitor C3 and one end of the resistor R30 are all electrically connected to the CS-terminal of the LED driving chip U1, the other end of the resistor R30 is electrically connected to one end of the resistor R29, the other end of the resistor R29 is electrically connected to one end of the nonpolar capacitor CB1, one end of the resistor R18, one end of the resistor 695r 2, one end of the resistor R56 and the other end of the resistor R17 are all electrically connected to the S-pole of the MOS transistor Q1, and the other end of the nonpolar capacitor C3, the other end of the resistor R18, the other end of the resistor R19 and the other end of the resistor R20 are all grounded.
Preferably, the driving control module further includes resistors R27 and R21 and a nonpolar capacitor C10, the output end of the LED driving chip U1 is the GATE end of the LED driving chip U1, the G electrode of the MOS tube Q1 is electrically connected to the GATE end of the LED driving chip U1 through the resistor R27, the resistor R21 is electrically connected between the G electrode and the S electrode of the MOS tube Q1, the D electrode of the MOS tube Q1 is electrically connected to the non-dotted end of the primary winding of the transformer T1, and the nonpolar capacitor C10 is electrically connected between the D electrode and the S electrode of the MOS tube Q1.
Preferably, the output module further includes resistors R22, R23, R24, R25, a nonpolar capacitor C6, diodes D4 and D5, one end of the nonpolar capacitor C6, the anode of the diode D4, and the anode of the diode D5 are also electrically connected to the same-name end of the secondary winding of the transformer T1, one end of the resistor R22 and one end of the resistor R23 are both electrically connected to the other end of the nonpolar capacitor C6, the other end of the resistor R22, the other end of the resistor R23, one end of the resistor R24, one end of the resistor R25, the cathode of the diode D4, the cathode of the diode D5 are also electrically connected to the anode of the polar capacitor EC4, and the other end of the resistor R24, the other end of the resistor R25, the cathode of the polar capacitor EC4, and the non-name end of the secondary winding of the transformer T1 are all connected to the SGND end.
Preferably, the output module further includes nonpolar capacitors CY1 and CY2, one end of the nonpolar capacitor CY1 is electrically connected to the dotted terminal of the primary winding of the transformer T1, the other end of the nonpolar capacitor CY1 is electrically connected to the positive electrode of the polar capacitor EC4, one end of the nonpolar capacitor CY2 is electrically connected to the non-dotted terminal of the secondary winding of the transformer T1, and the other end of the nonpolar capacitor CY2 is electrically connected to the non-dotted terminal of the auxiliary winding of the transformer T1.
Preferably, the bridge rectifier unit comprises a rectifier bridge stack DB1, a low-frequency band-pass filter LF1, a fuse F1, a variable resistor VR1, resistors R211 and R212 and a non-polar capacitor CX1, one end of the fuse F1 is electrically connected with a live wire of a mains supply, one end of the variable resistor VR1, one end of the resistor R212 and one end of the non-polar capacitor CX1 are electrically connected with the other end of the fuse F1, one end of the resistor R211 is electrically connected with the other end of the resistor R212, the other end of the resistor R211, the other end of the variable resistor VR1 and the other end of the non-polar capacitor CX1 are electrically connected with a zero line of the commercial power, the input end of the low-frequency band-pass filter LF1 is connected in parallel with the non-polar capacitor CX1, the output end of the low-frequency band-pass filter LF1 is electrically connected with the input end of the rectifier bridge stack DB1, the direct current output positive pole of the rectifier bridge stack DB1 is the direct current output end of the bridge stack rectifying unit, and the direct current output negative pole of the rectifier bridge stack DB1 is grounded.
In the harmonic-improved LED drive circuit, a bridge rectifier unit is used for converting mains supply supplied with power into direct current through a rectifier bridge, an RCD harmonic improvement unit is used for carrying out harmonic filtering processing on input, and an isolation flyback unit is used for providing an output power supply for a load to use for an output module through a transformer T1 playing an isolation role. The RCD harmonic wave improving unit can filter the input rectified alternating current, can improve the PF value, reduce THD, improve the harmonic wave, and meet IEC 61000-3-2: 2018. The polar capacitor EC1 is used for filtering, so that power frequency ripples can be removed, the isolation flyback unit at the rear end is not interfered by the power frequency ripples, and the output to a load (an LED lamp and the like) is free of stroboflash and meets the lighting standard.
Drawings
The drawings are further illustrative of the utility model and the content of the drawings does not constitute any limitation of the utility model.
FIG. 1 is a schematic diagram of a harmonic-improved LED driver circuit according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of an RCD harmonic-improving unit according to one embodiment of the present invention;
fig. 3 is a schematic diagram of an isolated flyback unit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a drive control module according to an embodiment of the present invention.
Wherein: a bridge rectifier unit 1; an RCD harmonic wave improving unit 2; an isolated flyback unit 3; an input module 31; an output module 32; a drive control module 33; a chip start-up module 34; an output current control module 35.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
The technical scheme of the utility model is further explained by the specific implementation mode in combination with the attached drawings.
As shown in fig. 1, the harmonic-improved LED driving circuit of this embodiment includes a bridge rectifier unit 1, an RCD harmonic improvement unit 2, and an isolation flyback unit 3, where an input end of the RCD harmonic improvement unit 2 is electrically connected to a dc output end of the bridge rectifier unit 1, and an output end of the RCD harmonic improvement unit 2 is electrically connected to an input end of the isolation flyback unit 3;
as shown in fig. 2, the RCD harmonic improvement unit 2 includes a resistor R1, a diode D1, a non-polar capacitor CB1, and a polar capacitor EC1, the isolated flyback unit 3 includes an input module 31, a transformer T1, an output module 32, and a driving control module 33, one end of the resistor R1, a negative electrode of the diode D1, one end of the non-polar capacitor CB1, and an input end of the input module 31 are all electrically connected to the dc output end of the bridge rectifier unit 1, an anode of the diode D1, another end of the resistor R1 are all electrically connected to a positive electrode of the polar capacitor EC1, and another end of the non-polar capacitor CB1 and a negative electrode of the polar capacitor EC1 are all grounded;
as shown in fig. 3, the output terminal of the input module 31 is electrically connected to the primary winding of the transformer T1, the driving control module 33 includes an LED driving chip U1 and an MOS transistor Q1, the power input terminal of the LED driving chip U1 is electrically connected to the output terminal of the RCD harmonic wave improving unit 2, the G pole of the MOS transistor Q1 is electrically connected to the output terminal of the LED driving chip U1, the D pole of the MOS transistor Q1 is electrically connected to the primary winding of the transformer T1, and the S pole of the MOS transistor Q1 is grounded;
the output module 32 comprises a diode D3 and a polarity capacitor EC4, the positive electrode of the diode D3 is electrically connected with the same-name end of the secondary winding of the transformer T1, the negative electrode of the diode D3 is electrically connected with the positive electrode of the polarity capacitor EC4, and the negative electrode of the polarity capacitor EC4 is electrically connected with the non-same-name end of the secondary winding of the transformer T1.
In the harmonic-improved LED driving circuit, the bridge rectifier unit 1 is used to convert the mains supply of the power supply into direct current through the rectifier bridge, the RCD harmonic-improving unit 2 is used to perform harmonic filtering processing on the input, and the isolation flyback unit 3 is used to provide the output power supply for the load through the transformer T1 playing an isolation role for the output module 32.
The working principle of the RCD harmonic wave improving unit 2 is that alternating current at the input end of the bridge rectifier unit 1 is sine wave, when the amplitude of direct current output voltage of the bridge rectifier unit 1 is increased and is larger than the voltage of the polar capacitor EC1, the polar capacitor EC1 is charged, and when the current passes through the resistor R1, the resistor R1 limits the current, so that the current follows the voltage, the PF value is improved, and THD (total harmonic current distortion) is reduced; when the amplitude of the direct current output voltage is reduced and is smaller than the voltage of the polar capacitor EC1, the polar capacitor EC1 provides energy for a rear-end circuit, and the current is output through the diode D1, so that the efficiency is improved; the non-polar capacitor CB1 also functions as a high frequency filter.
In the driving control module 33 of the isolated flyback unit 3, the LED driving chip U1 controls the on/off state of the MOS transistor Q1. When the MOS transistor Q1 is turned on, current flows through the primary winding of the transformer T1, and energy is stored in the transformer T1; when the MOS transistor Q1 is turned off, the energy stored in the transformer T1 is released through the secondary winding, rectified by the diode D3, and filtered by the polar capacitor EC4, and then supplied to the load (LED lamp, etc.).
RCD harmonic improves unit 2 can filter the alternating current after the rectification of input, can improve the PF value, reduces THD, improves the harmonic, satisfies IEC 61000-3-2: 2018. The polar capacitor EC1 is used for filtering, so that power frequency ripples can be removed, the isolation flyback unit 3 at the rear end is not interfered by the power frequency ripples, and the output to a load (an LED lamp and the like) is free of stroboflash and meets the lighting standard.
It should be noted that the LED driving chip U1 has a model number OB 3398. The polar capacitors used in this embodiment are all aluminum electrolytic capacitors.
Preferably, as shown in fig. 3, the isolated flyback unit 3 further includes a chip start module 34, the chip start module 34 includes resistors R10, R11, R28, a jumper resistor R01, a diode D2, a non-polar capacitor C5 and a polar capacitor EC3, one end of the resistor R10 is electrically connected to one end of the non-polar capacitor CB1, the other end of the resistor R10 is electrically connected to one end of the resistor R11, the other end of the resistor R11 and the negative electrode of the diode D2 are both electrically connected to one end of the jumper resistor R01, the positive electrode of the diode D2 is electrically connected to one end of the resistor R28, the other end of the resistor R28 is electrically connected to the same-name end of the auxiliary winding of the transformer T1, the non-name end of the auxiliary winding of the transformer T1 is grounded, and the auxiliary winding of the transformer T1 is connected to the same-side winding;
the other end of the jumper resistor R01, one end of the nonpolar capacitor C5 and the positive electrode of the polar capacitor EC3 are electrically connected with the VDD end of the LED driving chip U1, and the other end of the nonpolar capacitor C5, the negative electrode of the polar capacitor EC3 and the GND end of the LED driving chip U1 are all grounded.
In the chip start module 34, the resistors R10 and R11 charge the polar capacitor EC3 when the power supply is just started, so that the voltage of the polar capacitor EC3 rises from 0 to the start voltage of the LED driving chip U1, and the LED driving chip U1 starts to operate. When the power supply is started and the LED driving chip U1 works normally, the auxiliary winding of the transformer T1 provides energy, and the diode D2 plays a role in rectification; the non-polar capacitor C5 has a filtering effect, high-frequency interference is filtered, and the LED driving chip U1 is prevented from being interfered.
Further, the chip start module 34 further includes resistors R15, R16, R26 and nonpolar capacitors C1, C4, one end of the resistor R15 is electrically connected to the dotted terminal of the auxiliary winding of the transformer T1, the other end of the resistor R15, one end of the resistor R16, one end of the resistor R26, and one end of the nonpolar capacitor C4 are all electrically connected to the INV terminal of the LED driving chip U1, one end of the nonpolar capacitor C1 is electrically connected to the COMP terminal of the LED driving chip U1, and the other end of the resistor R16, the other end of the resistor R26, the other end of the nonpolar capacitor C4, and the other end of the nonpolar capacitor C1 are all grounded.
The resistors R15, R16, R26 divide the signal of the auxiliary winding of the transformer T1 and supply it to the LED driving chip U1, and since the turn ratio of the auxiliary winding and the secondary winding of the transformer T1 is fixed, the output voltage can be set and controlled by detecting the auxiliary winding. The non-polar capacitors C1 and C4 play a role in filtering, high-frequency interference is filtered, and the LED driving chip U1 is prevented from being interfered.
Specifically, as shown in fig. 3, the input module 31 includes resistors R6, R7, R13, a diode D1, and a non-polar capacitor C2, one end of the resistor R6, one end of the resistor R7, one end of the resistor R13, one end of the non-polar capacitor C2, and one end of the non-polar capacitor CB1 are all electrically connected to the same-name end of the primary winding of the transformer T1, the positive electrode of the diode D1 is electrically connected to the different-name end of the primary winding, and the other end of the resistor R6, the other end of the resistor R7, the other end of the resistor R13, and the other end of the non-polar capacitor C2 are electrically connected to the negative electrode of the diode D1.
Optionally, as shown in fig. 4, the isolated flyback unit 3 further includes an output current control module 35, an S-pole of the MOS transistor Q1 is grounded through the output current control module 35, the output current control module 35 includes resistors R17, R18, R19, R20, R29, R30 and a nonpolar capacitor C3, one end of the resistor R17, one end of the nonpolar capacitor C3, and one end of the resistor R30 are all connected to a CS terminal of the LED driving chip U1, the other end of the resistor R30 is electrically connected to one end of the resistor R29, the other end of the resistor R29 is electrically connected to one end of the nonpolar capacitor CB1, one end of the resistor R9, one end of the resistor R19, one end of the resistor R20, and the other end of the resistor R17 are all electrically connected to an S-pole of the MOS transistor Q1, and the other end of the nonpolar capacitor C3, the other end of the resistor R6867, the other end of the resistor R363687458 are all grounded.
In the output current control module 35, when a current flows through the resistors R18, R19 and R20, a corresponding voltage is generated, and the voltage is filtered by the resistor R17 and the nonpolar capacitor C3 and then provided to the LED driving chip U1, because the turn ratio of the primary winding and the secondary winding of the transformer T1 is fixed, the LED driving chip U1 can control the output current through the signal.
Furthermore, as shown in fig. 3, the driving control module 33 further includes resistors R27 and R21 and a non-polar capacitor C10, an output end of the LED driving chip U1 is a GATE end of the LED driving chip U1, a G electrode of the MOS transistor Q1 is electrically connected to the GATE end of the LED driving chip U1 through the resistor R27, the resistor R21 is electrically connected between the G electrode and an S electrode of the MOS transistor Q1, a D electrode of the MOS transistor Q1 is electrically connected to a non-dotted terminal of a primary winding of the transformer T1, and the non-polar capacitor C10 is electrically connected between the D electrode and the S electrode of the MOS transistor Q1.
As shown in fig. 3, the output module 32 further includes resistors R22, R23, R24, R25, a non-polar capacitor C6, diodes D4, and D5, one end of the non-polar capacitor C6, the anode of the diode D4, and the anode of the diode D5 are also electrically connected to the dotted terminal of the secondary winding of the transformer T1, one end of the resistor R22 and one end of the resistor R23 are both electrically connected to the other end of the non-polar capacitor C6, the other end of the resistor R22, the other end of the resistor R23, one end of the resistor R24, one end of the resistor R25, the cathode of the diode D4, the cathode of the diode D5 is also electrically connected to the anode of the polar capacitor EC4, and the other end of the resistor R24, the other end of the resistor R25, the cathode of the polar capacitor EC4, and the non-dotted terminal of the secondary winding of the transformer T1 are all connected to the SGND terminal.
The positive pole and the negative pole of the polar capacitor EC4 are the output ends of the output module 32. The rectifier diodes D3, D4, and D5 rectify the current of the secondary winding of the transformer T1 and output the rectified current to the load. The polar capacitor EC4 initiates a filtering action that smoothes the output current.
Preferably, the output module 32 further includes nonpolar capacitors CY1 and CY2, one end of the nonpolar capacitor CY1 is electrically connected to the dotted terminal of the primary winding of the transformer T1, the other end of the nonpolar capacitor CY1 is electrically connected to the positive electrode of the polar capacitor EC4, one end of the nonpolar capacitor CY2 is electrically connected to the non-dotted terminal of the secondary winding of the transformer T1, and the other end of the nonpolar capacitor CY2 is electrically connected to the non-dotted terminal of the auxiliary winding of the transformer T1.
More specifically, as shown in fig. 2, the bridge rectifier unit 1 includes a rectifier bridge DB1, a low-frequency band-pass filter LF1, a fuse F1, a variable resistor VR1, a resistor R211, a resistor R212 and a non-polar capacitor CX1, the live wire of the utility power is electrically connected to one end of the fuse F1, one end of the variable resistor VR1, one end of the resistor R212, one end of the non-polar capacitor CX1 are electrically connected to another end of the fuse F1, one end of the resistor R211 is electrically connected to the other end of the resistor R212, the other end of the variable resistor VR1 and the other end of the non-polar capacitor CX1 are electrically connected to the live wire, the input end of the low-frequency band-pass filter LF1 is connected in parallel to the non-polar capacitor CX1, the output end of the low-frequency band-pass filter LF1 is electrically connected to the input end of the rectifier bridge DB1, the dc output of the rectifier bridge DB1 is the neutral wire of the bridge rectifier unit 1, the direct current output cathode of the rectifier bridge stack DB1 is grounded.
The fuse F1 in the bridge rectifier unit 1 plays a role in overcurrent protection for the whole LED drive circuit; the low-frequency band-pass filter LF1 cuts off high-frequency signals and allows low-frequency signals to pass, so that the harmonic waves input to the rectifier bridge stack DB1 are improved, and high-frequency interference is filtered; the bridge rectifier DB1 converts the supplied mains power into dc power for use by the isolated flyback unit 3.
The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the utility model and should not be construed in any way as limiting the scope of the utility model. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims (10)

1. The utility model provides a LED drive circuit that harmonic improved, improves the unit and keeps apart the flyback unit including bridge rectifier unit, RCD harmonic, the input that RCD harmonic improved the unit is connected with bridge rectifier unit's direct current output electricity, the output that RCD harmonic improved the unit is connected with the input electricity of keeping apart the flyback unit, its characterized in that:
the RCD harmonic wave improving unit comprises a resistor R1, a diode D1, a nonpolar capacitor CB1 and a polar capacitor EC1, the isolation flyback unit comprises an input module, a transformer T1, an output module and a drive control module, one end of the resistor R1, the cathode of the diode D1, one end of the nonpolar capacitor CB1 and the input end of the input module are electrically connected with the direct current output end of the bridge rectifier unit, the anode of the diode D1 and the other end of the resistor R1 are electrically connected with the anode of the polar capacitor EC1, and the other end of the nonpolar capacitor CB1 and the cathode of the polar capacitor EC1 are grounded;
the output end of the input module is electrically connected with the primary winding of the transformer T1, the drive control module comprises an LED drive chip U1 and an MOS tube Q1, the power input end of the LED drive chip U1 is electrically connected with the output end of the RCD harmonic wave improvement unit, the G pole of the MOS tube Q1 is electrically connected with the output end of the LED drive chip U1, the D pole of the MOS tube Q1 is electrically connected with the primary winding of the transformer T1, and the S pole of the MOS tube Q1 is grounded;
the output module comprises a diode D3 and a polarity capacitor EC4, the anode of the diode D3 is electrically connected with the same-name end of the secondary winding of the transformer T1, the cathode of the diode D3 is electrically connected with the anode of the polarity capacitor EC4, and the cathode of the polarity capacitor EC4 is electrically connected with the non-same-name end of the secondary winding of the transformer T1.
2. The harmonically improved LED driver circuit of claim 1, wherein: the model of the LED driving chip U1 is OB 3398.
3. The harmonically improved LED driver circuit of claim 1, wherein:
the isolation flyback unit further comprises a chip starting module, the chip starting module comprises resistors R10, R11, R28, a jumper resistor R01, a diode D2, a non-polar capacitor C5 and a polar capacitor EC3, one end of the resistor R10 is electrically connected with one end of the non-polar capacitor CB1, the other end of the resistor R10 is electrically connected with one end of the resistor R11, the other end of the resistor R11 and the negative electrode of the diode D2 are electrically connected with one end of the jumper resistor R01, the positive electrode of the diode D2 is electrically connected with one end of the resistor R28, the other end of the resistor R28 is electrically connected with the same-name end of an auxiliary winding of a transformer T1, the non-name end of the auxiliary winding of the transformer T1 is grounded, and the auxiliary winding of the transformer T1 is on the same side as the winding;
the other end of the jumper resistor R01, one end of the nonpolar capacitor C5 and the positive electrode of the polar capacitor EC3 are electrically connected with the VDD end of the LED driving chip U1, and the other end of the nonpolar capacitor C5, the negative electrode of the polar capacitor EC3 and the GND end of the LED driving chip U1 are all grounded.
4. The harmonically improved LED driver circuit of claim 3, wherein: the chip starting module further comprises resistors R15, R16, R26 and nonpolar capacitors C1 and C4, one end of the resistor R15 is electrically connected with the same-name end of an auxiliary winding of the transformer T1, the other end of the resistor R15, one end of the resistor R16, one end of the resistor R26 and one end of the nonpolar capacitor C4 are electrically connected with the INV end of the LED driving chip U1, one end of the nonpolar capacitor C1 is electrically connected with the COMP end of the LED driving chip U1, and the other end of the resistor R16, the other end of the resistor R26, the other end of the nonpolar capacitor C4 and the other end of the nonpolar capacitor C1 are all grounded.
5. The harmonically improved LED driver circuit of claim 1, wherein: the input module comprises resistors R6, R7, R13, a diode D1 and a nonpolar capacitor C2, one end of the resistor R6, one end of the resistor R7, one end of the resistor R13, one end of the nonpolar capacitor C2 and one end of the nonpolar capacitor CB1 are all electrically connected with the same-name end of the primary winding of the transformer T1, the anode of the diode D1 is electrically connected with the non-same-name end of the primary winding, and the other end of the resistor R6, the other end of the resistor R7, the other end of the resistor R13 and the other end of the nonpolar capacitor C2 are all electrically connected with the cathode of the diode D1.
6. The harmonically improved LED driver circuit of claim 1, wherein: the isolation flyback unit further comprises an output current control module, the S pole of the MOS transistor Q1 is grounded through the output current control module, the output current control module comprises resistors R17, R18, R19, R20, R29, R30 and a nonpolar capacitor C3, one end of the resistor R17, one end of the nonpolar capacitor C3 and one end of the resistor R30 are all electrically connected with the CS end of the LED driving chip U1, the other end of the resistor R30 is electrically connected with one end of the resistor R29, the other end of the resistor R29 is electrically connected with one end of the nonpolar capacitor CB1, one end of the resistor R18, one end of the resistor R19, one end of the resistor R20 and the other end of the resistor R17 are all electrically connected with the S pole of the MOS transistor Q1, and the other end of the nonpolar capacitor C3, the other end of the resistor R18, the other end of the resistor R19 and the other end of the resistor R20 are all grounded.
7. The harmonically improved LED driver circuit of claim 1, wherein: the drive control module further comprises resistors R27 and R21 and a nonpolar capacitor C10, the output end of the LED drive chip U1 is the GATE end of the LED drive chip U1, the G pole of the MOS tube Q1 is electrically connected with the GATE end of the LED drive chip U1 through the resistor R27, the resistor R21 is electrically connected between the G pole and the S pole of the MOS tube Q1, the D pole of the MOS tube Q1 is electrically connected with the non-dotted end of the primary winding of the transformer T1, and the nonpolar capacitor C10 is electrically connected between the D pole and the S pole of the MOS tube Q1.
8. The harmonically improved LED driver circuit of claim 1, wherein: the output module further comprises resistors R22, R23, R24, R25, a nonpolar capacitor C6, diodes D4 and D5, one end of the nonpolar capacitor C6, the anode of the diode D4 and the anode of the diode D5 are also electrically connected with the same-name end of the secondary winding of the transformer T1, one end of the resistor R22 and one end of the resistor R23 are both electrically connected with the other end of the nonpolar capacitor C6, the other end of the resistor R22, the other end of the resistor R23, one end of the resistor R24, one end of the resistor R25, the cathode of the diode D4 and the cathode of the diode D5 are also electrically connected with the anode of the polar capacitor EC4, and the other end of the resistor R24, the other end of the resistor R25, the cathode of the polar capacitor EC4 and the non-name end of the secondary winding of the transformer T1 are all connected with the SGND end.
9. The harmonically improved LED driver circuit of claim 8, wherein: the output module further comprises nonpolar capacitors CY1 and CY2, one end of the nonpolar capacitor CY1 is electrically connected with the same-name end of the primary winding of the transformer T1, the other end of the nonpolar capacitor CY1 is electrically connected with the positive electrode of the polar capacitor EC4, one end of the nonpolar capacitor CY2 is electrically connected with the different-name end of the secondary winding of the transformer T1, and the other end of the nonpolar capacitor CY2 is electrically connected with the different-name end of the auxiliary winding of the transformer T1.
10. The harmonically improved LED driver circuit of claim 1, wherein: the bridge rectifier unit comprises a rectifier bridge DB1, a low-frequency band-pass filter LF1, a fuse F1, a variable resistor VR1, resistors R211 and R212 and a non-polar capacitor CX1, one end of the fuse F1 is electrically connected with a live wire of a mains supply, one end of the variable resistor VR1, one end of the resistor R212 and one end of the non-polar capacitor CX1 are electrically connected with the other end of the fuse F1, one end of the resistor R211 is electrically connected with the other end of the resistor R212, the other end of the resistor R211, the other end of the variable resistor VR1 and the other end of the non-polar capacitor CX1 are electrically connected with a zero line of the commercial power, the input end of the low-frequency band-pass filter LF1 is connected in parallel with the non-polar capacitor CX1, the output end of the low-frequency band-pass filter LF1 is electrically connected with the input end of the rectifier bridge stack DB1, the direct current output positive pole of the rectifier bridge stack DB1 is the direct current output end of the bridge stack rectifying unit, and the direct current output negative pole of the rectifier bridge stack DB1 is grounded.
CN202023083261.4U 2020-12-17 2020-12-17 Harmonic improved LED drive circuit Active CN215379291U (en)

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