WO2018196654A1 - Ripple suppression circuit - Google Patents

Ripple suppression circuit Download PDF

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Publication number
WO2018196654A1
WO2018196654A1 PCT/CN2018/083338 CN2018083338W WO2018196654A1 WO 2018196654 A1 WO2018196654 A1 WO 2018196654A1 CN 2018083338 W CN2018083338 W CN 2018083338W WO 2018196654 A1 WO2018196654 A1 WO 2018196654A1
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WO
WIPO (PCT)
Prior art keywords
transistor
resistor
diode
suppression circuit
ripple suppression
Prior art date
Application number
PCT/CN2018/083338
Other languages
French (fr)
Inventor
Egbert MAO
Steven Chen
Scotty ZHONG
Original Assignee
Tridonic Gmbh & Co Kg
Priority date (The priority date 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 date listed.)
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Publication date
Application filed by Tridonic Gmbh & Co Kg filed Critical Tridonic Gmbh & Co Kg
Publication of WO2018196654A1 publication Critical patent/WO2018196654A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G05F1/562—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices with a threshold detection shunting the control path of the final control device
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H02M1/15—Arrangements for reducing ripples from dc input or output using active elements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/385—Switched mode power supply [SMPS] using flyback topology
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/395—Linear regulators
    • 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]

Definitions

  • the invention relates to a ripple suppression circuit preferably for a LED driver, used for supplying a ripple suppression circuit for a control circuit of a switched power supply.
  • the invention relates to a ripple suppression circuit, characterized in that the ripple suppression circuit comprises a first transistor, a second transistor and a third transistor; the first transistor being connected in series to the second transistor to form a Darlington transistor; and the third transistor being connected in parallel to the Darlington transistor formed by the first transistor and the second transistor to control on/off of the Darlington transistor.
  • the first transistor, the second transistor and the third transistor may be bipolar transistors.
  • the first transistor, the second transistor and the third transistor may be NPN bipolar transistors.
  • the ripple suppression circuit may further comprise a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein, the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor is connected to a ground terminal; the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode; an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the second transistor and a collector of the third transistor; a base of the first transistor is connected to an emitter of the second transistor, and a collector of the first transistor is connected to a positive pole of the first diode and a collector of the second transistor; a base of the third transistor is
  • the capacitor may be an electrolytic capacitor, and the second diode may be a zener diode.
  • the ripple suppression circuit may comprise a first transistor and a second transistor; the second transistor and the first transistor being connected in parallel to control on/off of the first transistor.
  • the first transistor and the second transistor may be bipolar transistors.
  • the first transistor and the second transistor are NPN bipolar transistors.
  • the ripple suppression circuit may further comprise a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein, the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor is connected to a ground terminal; the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode; an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the first transistor and a collector of the second transistor; a collector of the first transistor is connected to a positive pole of the first diode; a base of the second transistor is connected to an emitter of the first transistor via the fifth resistor; and the third resistor and the fourth resistor are connected
  • the invention also relates to a voltage converter comprising a ripple suppression circuit according to the invention.
  • the invention also relates a LED driver, comprising a voltage converter comprising a ripple suppression circuit as described above, the ripple suppression circuit supplying an output current for the LED driven by the voltage converter, whereby the LED driver preferably comprises a flyback converter.
  • the one or more LED driven by the LED driver may be powered from the secondary winding.
  • Figure 1 is a schematic diagram of a converter circuit comprising a ripple suppression circuit
  • Figure 2 is a schematic diagram a part of the ripple suppression circuit in accordance with an embodiment of the present invention.
  • a voltage converter as switched power supply in this example a flyback converter, comprising a control circuit and a ripple suppression circuit comprising a ripple switch M1 which may be formed by a MOSFET.
  • the flyback converter comprises a flyback switch S1 which is connected in series to the primary winding T20a of a transformer.
  • One end of the secondary winding T20c of the transformer is connected to the cathode of a rectifying diode D52.
  • the ripple suppression circuit comprising a ripple switch M1 follows at the connection points + and –which are connected to one end of the secondary winding T20c and the anode of the rectifying diode D52.
  • the flyback switch S1 may be controlled by a control circuit which is not shown.
  • a primary side current may be flowing the primary winding T20a when the flyback switch S1 is switched on.
  • a voltage may be induced into the primary winding T20a when a primary side current is flowing in the primary winding T20a.
  • the primary side current through the primary winding T20a reaches a predefined maximum level, the control circuit may be able to detect this, e.g. by a sense resistor placed in series with the flyback switch S1.
  • the voltage across the primary winding T20a may be transferred to an auxiliary winding (not shown here) may be forwarded to a sensing pin of the control circuit.
  • the control circuit may detect by the aid of the monitoring of the voltage across the auxiliary winding when time point when the transformer has been demagnetized after the current through the secondary winding T20c has reached zero.
  • the control circuit may switch on the flyback switch S1 when it has detected that the transformer has been demagnetized. If the charge flyback switch S1 is switched on a primary side current will flow through the flyback switch S1 and the primary winding T20a.
  • the control circuit may open the flyback switch S1.
  • the primary side current will be interrupted by opening the flyback switch S1.
  • the load which may be for instance one or more LED.
  • the load e.g. the LED, may be connected to the output connections +LED and –LED following after the ripple suppression circuit with ripple switch M1.
  • the secondary side current will flow as long as the transformer is magnetized. Across the output connections +LED and –LED the output voltage Vout will be applied.
  • Figure 2 shows one embodiment according to the invention.
  • Figure 2 shows a part of a voltage converter circuit as switched power supply, in this example a flyback converter.
  • the flyback converter again comprises a flyback switch which is connected in series to the primary winding of a transformer.
  • One end of the secondary winding of the transformer is connected to the cathode of a rectifying diode.
  • the ripple suppression circuit shown in figure 2 follows at the connection points + and –which are connected to one end of the secondary winding and the anode of the rectifying diode.
  • the flyback switch, the primary winding and the secondary winding of the transformer as well as the rectifying diode are not shown in figure 2 but are arranged in a similar way as according to the circuit of figure 1.
  • the ripple suppression circuit of figure 2 comprises a first transistor Q1, a second transistor Q2 and a third transistor Q3.
  • the first transistor Q1 is connected in series to the second transistor Q2 to form a Darlington transistor; and the third transistor Q3 is connected in parallel to the Darlington transistor formed by the first transistor Q1 and the second transistor Q2 to control on/off of the Darlington transistor.
  • the first transistor Q1, the second transistor Q2 and the third transistor Q3 may be bipolar transistors.
  • the first transistor Q1, the second transistor Q2 and the third transistor Q3 may be NPN bipolar transistors.
  • the ripple suppression circuit may further comprise a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first diode D1, a second diode D2, and a capacitor C.
  • the first resistor R1 and the capacitor C are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor C is connected to a ground terminal.
  • the first diode D1 and the second diode D2 are connected in series first, and then connected to the first resistor R1 in parallel, a negative pole of the first diode D1 being connected to a negative pole of the second diode D2.
  • An end of the second resistor R2 is connected to a positive pole of the second diode D2, and the other end thereof is connected to a base of the second transistor Q2 and a collector of the third transistor Q3.
  • a base of the first transistor Q1 is connected to an emitter of the second transistor Q2, and a collector of the first transistor Q1 is connected to a positive pole of the first diode D1 and a collector of the second transistor Q2.
  • a base of the third transistor Q3 is connected to an emitter of the first transistor Q1 via the fifth resistor R5.
  • the third resistor R3 and the fourth resistor R4 are connected in parallel first, and then connected between the emitter of the first transistor Q1 and an emitter of the third transistor Q3.
  • the third transistor Q3 will be turned on if the output current which flows through the first transistor Q1 and through the third resistor R3 and fourth resistor R4 as well exceeds a certain limit, e.g. in case of a short circuit on the output. By turning on the third transistor Q3 the second transistor Q2 will be switched off and thus the first transistor Q1 will be switched off.
  • the capacitor C may be an electrolytic capacitor, and the second diode D2 may be a zener diode.
  • the ripple suppression circuit may comprise a first transistor Q1 and a second transistor Q2 whereby the second transistor Q2 and the first transistor Q1 being connected in parallel to control on/off of the first transistor Q1.
  • the first transistor Q1 and the second transistor Q2 may be bipolar transistors.
  • the first transistor Q1 and the second transistor Q2 are NPN bipolar transistors.
  • the ripple suppression circuit may further comprise a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first diode D1, a second diode D2, and a capacitor C.
  • the first resistor R1 and the capacitor C are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor C is connected to a ground terminal;
  • the first diode D1 and the second diode D2 are connected in series first, and then connected to the first resistor R1 in parallel, a negative pole of the first diode D1 being connected to a negative pole of the second diode D2.
  • An end of the second resistor R2 is connected to a positive pole of the second diode D2, and the other end thereof is connected to a base of the first transistor Q1 and a collector of the second transistor Q2.
  • a collector of the first transistor Q1 is connected to a positive pole of the first diode D1.
  • a base of the second transistor Q2 is connected to an emitter of the first transistor Q1 via the fifth resistor R5.
  • the third resistor R3 and the fourth resistor R4 are connected in parallel first, and then connected between the emitter of the first transistor Q1 and an emitter of the second transistor Q2.
  • the invention also relates to a voltage converter comprising a ripple suppression circuit according to the invention.
  • the invention also relates a LED driver, comprising a voltage converter comprising a ripple suppression circuit as described above, the ripple suppression circuit supplying an output current for the LED driven by the voltage converter, whereby the LED driver preferably comprises a flyback converter.
  • the one or more LED driven by the LED driver may be powered from the secondary winding T20c.
  • T20a primary winding of transformer
  • T20c secondary winding of transformer

Abstract

A ripple suppression circuit comprising a first transistor, a second transistor and a third transistor; the first transistor being connected in series to the second transistor to form a Darlington transistor; and the third transistor being connected in parallel to the Darlington transistor formed by the first transistor and the second transistor to control on/off of the Darlington transistor.

Description

Ripple suppression circuit FIELD OF THE INVENTION
The invention relates to a ripple suppression circuit preferably for a LED driver, used for supplying a ripple suppression circuit for a control circuit of a switched power supply.
BACKGROUND
Nowadays, modern LED (Light Emitting Diode) driver use converter to provide constant current. Typical circuits to drive a LED are flyback converters or buck converters. However, the applicant found that output current stability regarding the ripple may be improved.
SUMMARY
The invention relates to a ripple suppression circuit, characterized in that the ripple suppression circuit comprises a first transistor, a second transistor and a third transistor; the first transistor being connected in series to the second transistor to form a Darlington transistor; and the third transistor being connected in parallel to the Darlington transistor formed by the first transistor and the second transistor to control on/off of the Darlington transistor.
The first transistor, the second transistor and the third transistor may be bipolar transistors. The first transistor, the second transistor and the third transistor may be NPN bipolar transistors.
The ripple suppression circuit may further comprise a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein, the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit,  and the capacitor is connected to a ground terminal; the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode; an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the second transistor and a collector of the third transistor; a base of the first transistor is connected to an emitter of the second transistor, and a collector of the first transistor is connected to a positive pole of the first diode and a collector of the second transistor; a base of the third transistor is connected to an emitter of the first transistor via the fifth resistor; and the third resistor and the fourth resistor are connected in parallel first, and then connected between the emitter of the first transistor and an emitter of the third transistor.
The capacitor may be an electrolytic capacitor, and the second diode may be a zener diode.
The ripple suppression circuit may comprise a first transistor and a second transistor; the second transistor and the first transistor being connected in parallel to control on/off of the first transistor.
The first transistor and the second transistor may be bipolar transistors. The first transistor and the second transistor are NPN bipolar transistors.
The ripple suppression circuit may further comprise a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein, the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor is connected to a ground terminal; the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode;  an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the first transistor and a collector of the second transistor; a collector of the first transistor is connected to a positive pole of the first diode; a base of the second transistor is connected to an emitter of the first transistor via the fifth resistor; and the third resistor and the fourth resistor are connected in parallel first, and then connected between the emitter of the first transistor and an emitter of the second transistor.
The invention also relates to a voltage converter comprising a ripple suppression circuit according to the invention.
The invention also relates a LED driver, comprising a voltage converter comprising a ripple suppression circuit as described above, the ripple suppression circuit supplying an output current for the LED driven by the voltage converter, whereby the LED driver preferably comprises a flyback converter.
The one or more LED driven by the LED driver may be powered from the secondary winding.
These and further aspects and features of the present invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the invention may be employed, but it is understood that the invention is not limited correspondingly in scope. Rather, the invention includes all changes, modifications and equivalents coming within the spirit and terms of the appended claims.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. To facilitate illustrating and describing some parts of the invention, corresponding portions of the drawings may be exaggerated in size, e.g., made larger in relation to other parts than in an exemplary device actually made according to the invention. Elements and features depicted in one drawing or embodiment of the invention may be combined with elements and features depicted in one or more additional drawings or embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views and may be used to designate like or similar parts in more than one embodiment.
BRIEF DESCRIPTION OF THE DRAWING
The drawings are included to provide further understanding of the present invention, which constitute a part of the specification and illustrate the preferred embodiments of the present invention, and are used for setting forth the principles of the present invention together with the description. The same element is represented with the same reference number throughout the drawings.
In the drawings:
Figure 1 is a schematic diagram of a converter circuit comprising a ripple suppression circuit;
Figure 2 is a schematic diagram a part of the ripple suppression circuit in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
The many features and advantages of the embodiments are apparent from the detailed specification and, thus, it is intended by the appended claims to cover all such features and advantages of the embodiments that fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the inventive embodiments to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope thereof.
As shown in Figure 1, there is a voltage converter as switched power supply, in this example a flyback converter, comprising a control circuit and a ripple suppression circuit comprising a ripple switch M1 which may be formed by a MOSFET. The flyback converter comprises a flyback switch S1 which is connected in series to the primary winding T20a of a transformer. One end of the secondary winding T20c of the transformer is connected to the cathode of a rectifying diode D52. The ripple suppression circuit comprising a ripple switch M1 follows at the connection points + and –which are connected to one end of the secondary winding T20c and the anode of the rectifying diode D52.
The flyback switch S1 may be controlled by a control circuit which is not shown.
A primary side current may be flowing the primary winding T20a when the flyback switch S1 is switched on.
A voltage may be induced into the primary winding T20a when a primary side current is flowing in the primary winding T20a. The primary side current through the primary winding T20a reaches a predefined maximum level, the control circuit may be able to detect this, e.g. by a sense resistor placed in series with the flyback switch S1.
The voltage across the primary winding T20a may be transferred to an auxiliary  winding (not shown here) may be forwarded to a sensing pin of the control circuit. The control circuit may detect by the aid of the monitoring of the voltage across the auxiliary winding when time point when the transformer has been demagnetized after the current through the secondary winding T20c has reached zero. The control circuit may switch on the flyback switch S1 when it has detected that the transformer has been demagnetized. If the charge flyback switch S1 is switched on a primary side current will flow through the flyback switch S1 and the primary winding T20a.
When the primary side current through the primary winding T20a has reached a predefined maximum level, the control circuit may open the flyback switch S1. The primary side current will be interrupted by opening the flyback switch S1. As the transformer is magnetized a secondary side current will flow through the secondary winding T20c via the ripple suppression circuit to the load which may be for instance one or more LED. The load, e.g. the LED, may be connected to the output connections +LED and –LED following after the ripple suppression circuit with ripple switch M1. The secondary side current will flow as long as the transformer is magnetized. Across the output connections +LED and –LED the output voltage Vout will be applied.
Figure 2 shows one embodiment according to the invention. Figure 2 shows a part of a voltage converter circuit as switched power supply, in this example a flyback converter. The flyback converter again comprises a flyback switch which is connected in series to the primary winding of a transformer. One end of the secondary winding of the transformer is connected to the cathode of a rectifying diode. The ripple suppression circuit shown in figure 2 follows at the connection points + and –which are connected to one end of the secondary winding and the anode of the rectifying diode. The flyback switch, the primary winding and the secondary winding of the transformer as well as the rectifying diode are not shown in figure 2 but are arranged in a similar way as according to the circuit of figure 1.
In difference to figure 1 the ripple suppression circuit of figure 2 comprises a first transistor Q1, a second transistor Q2 and a third transistor Q3. The first transistor Q1 is connected in series to the second transistor Q2 to form a Darlington transistor; and the third transistor Q3 is connected in parallel to the Darlington transistor formed by the first transistor Q1 and the second transistor Q2 to control on/off of the Darlington transistor.
The first transistor Q1, the second transistor Q2 and the third transistor Q3 may be bipolar transistors. The first transistor Q1, the second transistor Q2 and the third transistor Q3 may be NPN bipolar transistors.
The ripple suppression circuit may further comprise a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first diode D1, a second diode D2, and a capacitor C. The first resistor R1 and the capacitor C are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor C is connected to a ground terminal. The first diode D1 and the second diode D2 are connected in series first, and then connected to the first resistor R1 in parallel, a negative pole of the first diode D1 being connected to a negative pole of the second diode D2. An end of the second resistor R2 is connected to a positive pole of the second diode D2, and the other end thereof is connected to a base of the second transistor Q2 and a collector of the third transistor Q3. A base of the first transistor Q1 is connected to an emitter of the second transistor Q2, and a collector of the first transistor Q1 is connected to a positive pole of the first diode D1 and a collector of the second transistor Q2. A base of the third transistor Q3 is connected to an emitter of the first transistor Q1 via the fifth resistor R5.The third resistor R3 and the fourth resistor R4 are connected in parallel first, and then connected between the emitter of the first transistor Q1 and an emitter of the third transistor Q3.
The third transistor Q3 will be turned on if the output current which flows through the first transistor Q1 and through the third resistor R3 and fourth resistor R4 as well exceeds a certain limit, e.g. in case of a short circuit on the output. By turning on the third transistor Q3 the second transistor Q2 will be switched off and thus the first transistor Q1 will be switched off.
The capacitor C may be an electrolytic capacitor, and the second diode D2 may be a zener diode.
The ripple suppression circuit may comprise a first transistor Q1 and a second transistor Q2 whereby the second transistor Q2 and the first transistor Q1 being connected in parallel to control on/off of the first transistor Q1.
The first transistor Q1 and the second transistor Q2 may be bipolar transistors. The first transistor Q1 and the second transistor Q2 are NPN bipolar transistors.
The ripple suppression circuit may further comprise a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first diode D1, a second diode D2, and a capacitor C. The first resistor R1 and the capacitor C are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor C is connected to a ground terminal; the first diode D1 and the second diode D2 are connected in series first, and then connected to the first resistor R1 in parallel, a negative pole of the first diode D1 being connected to a negative pole of the second diode D2. An end of the second resistor R2 is connected to a positive pole of the second diode D2, and the other end thereof is connected to a base of the first transistor Q1 and a collector of the second transistor Q2. A collector of the first transistor Q1 is connected to a positive pole of the first diode D1. A base of the second transistor Q2 is connected to an emitter of the  first transistor Q1 via the fifth resistor R5. The third resistor R3 and the fourth resistor R4 are connected in parallel first, and then connected between the emitter of the first transistor Q1 and an emitter of the second transistor Q2.
The invention also relates to a voltage converter comprising a ripple suppression circuit according to the invention.
The invention also relates a LED driver, comprising a voltage converter comprising a ripple suppression circuit as described above, the ripple suppression circuit supplying an output current for the LED driven by the voltage converter, whereby the LED driver preferably comprises a flyback converter.
The one or more LED driven by the LED driver may be powered from the secondary winding T20c.
List of references:
Q1: first transistor
Q2: second transistor
Q3: third transistor
R1: first resistor
R2: second resistor
R3: third resistor
R4: fourth resistor
R5: fifth resistor
D1: first diode
D2: second diode
C: capacitor
S1: flyback switch
M1: ripple switch
T20a: primary winding of transformer
T20c: secondary winding of transformer
D52: rectifying diode

Claims (11)

  1. A ripple suppression circuit, characterized in that the ripple suppression circuit comprises a first transistor, a second transistor and a third transistor;
    the first transistor being connected in series to the second transistor to form a Darlington transistor;
    and the third transistor being connected in parallel to the Darlington transistor formed by the first transistor and the second transistor to control on/off of the Darlington transistor.
  2. The ripple suppression circuit according to claim 1, characterized in that the first transistor, the second transistor and the third transistor are bipolar transistors.
  3. The ripple suppression circuit according to claim 2, characterized in that the first transistor, the second transistor and the third transistor are NPN bipolar transistors.
  4. The ripple suppression circuit according to claim 1, characterized in that the ripple suppression circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein,
    the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor is connected to a ground terminal;
    the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode;
    an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the second transistor and a collector of the third transistor;
    a base of the first transistor is connected to an emitter of the second transistor, and  a collector of the first transistor is connected to a positive pole of the first diode and a collector of the second transistor;
    a base of the third transistor is connected to an emitter of the first transistor via the fifth resistor;
    and the third resistor and the fourth resistor are connected in parallel first, and then connected between the emitter of the first transistor and an emitter of the third transistor.
  5. The ripple suppression circuit according to claim 4, characterized in that,
    the capacitor is an electrolytic capacitor, and the second diode is a zener diode.
  6. A ripple suppression circuit, characterized in that the ripple suppression circuit comprises a first transistor and a second transistor;
    the second transistor and the first transistor being connected in parallel to control on/off of the first transistor.
  7. The ripple suppression circuit according to claim 6, characterized in that the first transistor and the second transistor are bipolar transistors.
  8. The ripple suppression circuit according to claim 7, characterized in that the first transistor and the second transistor are NPN bipolar transistors.
  9. The ripple suppression circuit according to claim 6, characterized in that the ripple suppression circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, a second diode, and a capacitor; wherein,
    the first resistor and the capacitor are connected in series between a positive pole and a negative pole of an input voltage of the ripple suppression circuit, and the capacitor is connected to a ground terminal;
    the first diode and the second diode are connected in series first, and then connected to the first resistor in parallel, a negative pole of the first diode being connected to a negative pole of the second diode;
    an end of the second resistor is connected to a positive pole of the second diode, and the other end thereof is connected to a base of the first transistor and a collector of  the second transistor;
    a collector of the first transistor is connected to a positive pole of the first diode;
    a base of the second transistor is connected to an emitter of the first transistor via the fifth resistor;
    and the third resistor and the fourth resistor are connected in parallel first, and then connected between the emitter of the first transistor and an emitter of the second transistor.
  10. A voltage converter, characterized in that the voltage converter comprises the ripple suppression circuit as claimed in any one of claims 1-9.
  11. A LED driver, comprising a voltage converter as claimed in claims 10, voltage converter comprising a ripple suppression circuit as claimed in any one of claims 1-9, whereby the LED driver preferably comprises a flyback converter.
PCT/CN2018/083338 2017-04-27 2018-04-17 Ripple suppression circuit WO2018196654A1 (en)

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CN201720453934.XU CN206850681U (en) 2017-04-27 2017-04-27 Ripple suppression circuit and the electric pressure converter including the ripple suppression circuit
CN201720453934.X 2017-04-27
GB1719319.4 2017-11-21
GB1719319.4A GB2561934B (en) 2017-04-27 2017-11-21 Ripple suppression circuit

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CN206850681U (en) * 2017-04-27 2018-01-05 赤多尼科两合股份有限公司 Ripple suppression circuit and the electric pressure converter including the ripple suppression circuit
EP4136742A4 (en) * 2020-06-08 2023-06-07 Tridonic GmbH & Co KG Ripple suppression circuit, controlling method and driving equipment

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US4920307A (en) * 1988-07-19 1990-04-24 Asahi Kogaku Kogyo Kabushiki Kaisha Electric power source used to charge a secondary power source
CN102570798A (en) * 2010-12-30 2012-07-11 深圳市英威腾电气股份有限公司 Method for realizing constant voltage-second product auxiliary power supply in forward switching power supply and circuit
CN102412743A (en) * 2011-12-15 2012-04-11 苏州合欣美电子科技有限公司 Series voltage-stabilizing circuit used for small power type power circuit
CN104283418A (en) * 2014-10-21 2015-01-14 安庆中轴科技有限公司 Micro power consumption voltage stabilizer for quartz clock lithium battery
GB201719319D0 (en) * 2017-04-27 2018-01-03 Tridonic Gmbh & Co Kg Ripple suppression circuit
CN206850681U (en) * 2017-04-27 2018-01-05 赤多尼科两合股份有限公司 Ripple suppression circuit and the electric pressure converter including the ripple suppression circuit

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