EP3258743A1 - Direktangetriebene led-beleuchtung - Google Patents

Direktangetriebene led-beleuchtung Download PDF

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Publication number
EP3258743A1
EP3258743A1 EP16174276.2A EP16174276A EP3258743A1 EP 3258743 A1 EP3258743 A1 EP 3258743A1 EP 16174276 A EP16174276 A EP 16174276A EP 3258743 A1 EP3258743 A1 EP 3258743A1
Authority
EP
European Patent Office
Prior art keywords
circuit
current
terminal
switching device
power switching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP16174276.2A
Other languages
English (en)
French (fr)
Inventor
Chiu Sing Celement Tse
On Bon Peter Chan
Chi Keung Tang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mosway Semiconductor Ltd
Original Assignee
Mosway Semiconductor Ltd
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.)
Filing date
Publication date
Application filed by Mosway Semiconductor Ltd filed Critical Mosway Semiconductor Ltd
Priority to EP16174276.2A priority Critical patent/EP3258743A1/de
Priority to JP2016207151A priority patent/JP2017224586A/ja
Publication of EP3258743A1 publication Critical patent/EP3258743A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix

Definitions

  • the present invention relates to control circuits for LED lighting.
  • the invention more particularly, although not exclusively, relates to driving LEDs in LED lighting products using direct drive architecture.
  • circuit including:
  • a direct drive LED lighting circuit comprising:
  • a LED current control circuit with a power switching device; a current sensing device, an averaging circuit, and an error amplifier;
  • the power switching device with a control terminal to control the amount of current flowing through the switching channel, a current inflow terminal and a current outflow terminal as the positive channel terminal and the negative channel terminal of the power switching device respectively;
  • a current sensing device for sensing the current flowing through the power switching device is connecting between the negative channel terminal of the power switching device and the reference node (lowest voltage) of the control circuit, the output of the current sensing device (or negative channel terminal of the power switching device for particular implementation) is connecting to the input of an averaging circuit;
  • the averaging circuit with an input connected to the output of the current sensing device, and an output connected to one of the inputs of an error amplifier;
  • the error amplifier with an output of the averaging circuit as one of the inputs, and reference voltage serving for setting of an average LED current as another input, and an output connected to the control terminal of the power switching device;
  • a LED chain circuit by connecting several LEDs in series with a capacitor connecting in parallel with the series of LEDs, with a current flowing in terminal as a positive terminal, and a current leaving terminal as a negative terminal;
  • the LED chain circuit and the LED current control circuit are connecting in series and the whole circuit is connected between the positive and negative terminals of a rectified AC power source.
  • a series diode to prevent the reverse current flow may be added either at the positive terminal or the negative terminal of the rectified AC power source, or between the LED chain circuit and the LED current control circuit.
  • a filter circuit may be added between the error amplifier and the power switching device.
  • the current sensing device can take the form of a simple resistor, or current mirror followed by current to voltage conversion, to produce a voltage representing the current flowing through the power switching device.
  • the averaging circuit can take the form of passive low pass filter, or active low pass filter, or low pass filter with addition of sample and hold control for processing of the averaging function.
  • a monolithic integrated circuit for direct drive LED light application comprising the following:
  • a series diode to prevent the reverse current flow may be added either at the positive terminal or the negative terminal of the rectified AC power source, or between the LED chain circuit and the LED current control circuit.
  • a filter circuit may be added between the connection of the three input error amplifier and the power switching device.
  • the current sensing device can take the form of a simple resistor, or current mirror followed by current to voltage conversion, to produce a voltage representing the current flowing through the power switching device.
  • the averaging circuit can take the form of passive low pass filter, or active low pass filter, or low pass filter with addition of sample and hold control for processing of the averaging function.
  • a monolithic integrated circuit for direct drive LED light application comprising the following:
  • a filter circuit may be added between the connection of the error amplifier and the power switching device.
  • an external current sensing device Preferably, an external current sensing device, averaging circuit, and LED chain circuit may be connected to produce intended application circuits.
  • a direct drive LED control circuit which has LED current conduction for the whole AC half cycle as well as having low LED current variation, and hence a low flicker index, is required.
  • Fig. 3 is the block diagram for such a circuit.
  • Another input for setting the LED current is the internally generated Vref, which is connected to another input of error amplifier 302.
  • Output of error amplifier 302 is directly connected, or optionally via a filter, to the control input of the power switching device 305.
  • This feedback loop determines the current profile via power switching device 305, and hence the long term LED average current.
  • a series diode to block the reverse current flow may be added to the positive or negative side of the rectified AC power source, or between the parallel circuit formed by the LED chain 303 and the capacitor 304 and the power switching device 305.
  • Fig. 4 illustrates the AC half cycle voltage and current, as well as the LED current. It can be observed that the LED chain remains on for every full half cycle of AC as well as having relatively small current variation. Hence, flicker is reduced substantially as compared with the circuit shown in Fig.1 . In addition, the LED utilization is practically near 100%. However, the power factor performance is not as good as the prior act (which is practically near 1) but still satisfactory (near 0.9 with proper selection of voltage of the LED chain). Major heat dissipation at regions near the peak of the AC half cycles is similar.
  • Fig. 5 illustrates this alternative interconnecting circuit for achieving the same function.
  • the same monolithic circuit may be used to replace devices 502 and 505 in the circuit shown in Fig. 5 .
  • a further innovation of this invention to reduce the heat dissipation at the power switching device. This is achieved by reducing the current flowing through the power switching device when the AC instantaneous voltage is above a selected value. During such period, the LED current is the sum of the AC input current plus the current supplied by the capacitor in parallel with the LED chain. While the instantaneous LED current is reduced during such period, the long term average LED current remains constant according to the target set by the reference voltage and sensed by the current sensing device.
  • Fig. 7 illustrates a preferred design.
  • Fig. 7 is a modified version of Fig. 3 in which the two input error amplifier 302 is replaced by a three input error amplifier 702. Besides the original 2 inputs, a third input, which contains the voltage information of the AC line, is added to wave shape the AC current as described in the previous paragraph. When the AC instantantaneous voltage is above a pre-determined level, the AC input current is reduced according to the voltage in excess of the pre-selected level. This additional control signal has fast response and therefore modulates the AC line current immediately. While the signal for the third input pin of the error amplifier 702 is taken indirectly from the positive channel terminal of the power switching device in Fig. 7 , it can also be optionally taken from from a resistor divider across the rectified AC power source. Preferred design embodiments for the three input amplifier 702 are shown in Fig. 8 .
  • resistors 804, 805 and 805 divide down the signal from the positive channel terminal of the power switching device.
  • Comparator 803 compares one of the divided down signal with Vref to generate a control signal for the analogue multiplexor MUX 802. When the AC instantaneous voltage is above a desired value, this control signal is a logical '1'. When the AC instantaneous voltage is below such desired value, this control signal is a logical '0'.
  • MUX 802 selects a divided down signal of the positive channel terminal of the power switching device (which carries the information of instantaneous rectified AC voltage) to its output terminal.
  • MUX 802 selects a ground potential to its output terminal.
  • the output of the MUX 802 is summed with the output from the averaging circuit to generate the signal for one of the input of the error amplifier 807.
  • Another input for error amplifier 807 is the Vref.
  • Output of error amplifier 807 is then used to control the power switching device. With this circuit, current through the power switching device, and hence the AC line current, will be reduced near the peak of the AC cycle.
  • resistors 809, 810 and 811 divide down the signal from the positive channel terminal of the power switching device.
  • Comparator 812 compares one of the divided down signal with Vref to generate a control signal for the analogue multiplexor MUX 813.
  • this control signal is a logical '1'.
  • this control signal is a logical '0'.
  • MUX 813 selects a divided down signal of the positive channel terminal of the power switching device to its output terminal.
  • MUX 813 selects a ground potential to its output terminal.
  • the output of the MUX 813 is subtracted from the output of the error amplifier 808 to generate control signal for the power switching device.
  • Error amplifier 808 takes the output from the averaging circuit and Vref as inputs for controlling the long term average LED current. With this circuit, current through the power switching device, and hence the AC line current, will be reduced near the peak of the AC cycle.
  • Fig. 9 shows waveforms of key circuit nodes of Fig.7 .
  • the invented circuit using a selected error amplifier as shown in Fig. 8 , the heat dissipation at the power switch near the peak voltage of the AC cycle is reduced and hence the efficiency is improved, at the expenses of lowering the power factor.
  • Fig. 10 illustrates this alternative interconnecting circuit for achieving the same function.
  • the same monolithic circuit may be used to replace devices 1002 and 1005 in the circuit shown in Fig. 10 .
  • Fig. 12 illustrates two preferred design embodiments for the three input error amplifier in Fig.7 and Fig. 10 to achieve the desired effect.
  • resistors 1203 and 1204 divide down the signal from the positive channel terminal of the power switching device.
  • Comparator 1202 compares the divided down signal with Vref to generate a control signal for the analogue multiplexor MUX 1201.
  • this control signal is a logical '1'.
  • this control signal is a logical '0'.
  • MUX 1201 selects a logical '1', or the supply voltage for the control circuit, to its output terminal.
  • MUX 1201 selects the output from the averaging circuit to its output terminal.
  • the output of the MUX 1201 and Vref are inputs for error amplifier 1205 to generate the control signal for the power switching device.
  • resistors 1207 and 1208 divide down the signal from the positive channel terminal of the power switching device.
  • Comparator 1209 compares the divided down signal with Vref to generate a control signal for the analogue multipexor MUX 1210.
  • this control signal is a logical '1'.
  • this control signal is a logical '0'.
  • MUX 1210 selects a logical '0', or zero potential of the current control circuit, to its output terminal.
  • MUX 1210 selects the output from output of error amplifier 1206.
  • the output of the MUX 1210 is used to control the power switching device.
  • Error amplifier 1206 uses Vref and the output from the averaging circuit as inputs. With this circuit, current through the power switching device, and hence the AC line current, can be totally eliminated when the AC instantaneous voltage is above the desired value.
  • Fig. 13 shows waveforms of key circuit nodes of Fig.7 .

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)
EP16174276.2A 2016-06-13 2016-06-13 Direktangetriebene led-beleuchtung Withdrawn EP3258743A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP16174276.2A EP3258743A1 (de) 2016-06-13 2016-06-13 Direktangetriebene led-beleuchtung
JP2016207151A JP2017224586A (ja) 2016-06-13 2016-10-21 直接駆動型のｌｅｄ照明回路及びそれに用いるモノリシック集積回路

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP16174276.2A EP3258743A1 (de) 2016-06-13 2016-06-13 Direktangetriebene led-beleuchtung

Publications (1)

Publication Number Publication Date
EP3258743A1 true EP3258743A1 (de) 2017-12-20

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Family Applications (1)

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EP16174276.2A Withdrawn EP3258743A1 (de) 2016-06-13 2016-06-13 Direktangetriebene led-beleuchtung

Country Status (2)

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EP (1) EP3258743A1 (de)
JP (1) JP2017224586A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3506475A1 (de) * 2017-12-28 2019-07-03 Mitsumi Electric Co., Ltd. Stromversorgungsvorrichtung, integrierte halbleiterschaltung und verfahren zur unterdrückung von welligkeitskomponenten
CN114401570A (zh) * 2022-03-25 2022-04-26 南昌大学 一种可见光通信驱动电路

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7201900B2 (ja) * 2017-12-28 2023-01-11 ミツミ電機株式会社 電源装置、半導体集積回路及びリップル抑制方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2563094A2 (de) * 2011-08-26 2013-02-27 O2 Micro, Inc. Schaltungen und Verfahren zum Steuern von Lichtquellen
US20130187550A1 (en) * 2012-01-20 2013-07-25 Yuan-Hung Lo Led lighting circuit capable of preventing thermal breakdown
EP2958402A1 (de) * 2014-06-19 2015-12-23 Nxp B.V. Dimmbare LED-Beleuchtungsschaltungen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2563094A2 (de) * 2011-08-26 2013-02-27 O2 Micro, Inc. Schaltungen und Verfahren zum Steuern von Lichtquellen
US20130187550A1 (en) * 2012-01-20 2013-07-25 Yuan-Hung Lo Led lighting circuit capable of preventing thermal breakdown
EP2958402A1 (de) * 2014-06-19 2015-12-23 Nxp B.V. Dimmbare LED-Beleuchtungsschaltungen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3506475A1 (de) * 2017-12-28 2019-07-03 Mitsumi Electric Co., Ltd. Stromversorgungsvorrichtung, integrierte halbleiterschaltung und verfahren zur unterdrückung von welligkeitskomponenten
CN109980960A (zh) * 2017-12-28 2019-07-05 三美电机株式会社 电源装置、半导体集成电路以及脉动抑制方法
US10536082B2 (en) 2017-12-28 2020-01-14 Mitsumi Electric Co., Ltd. Power supply device, semiconductor integrated circuit, and method for suppressing ripple component
CN109980960B (zh) * 2017-12-28 2024-05-24 三美电机株式会社 电源装置、半导体集成电路以及脉动抑制方法
CN114401570A (zh) * 2022-03-25 2022-04-26 南昌大学 一种可见光通信驱动电路

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