WO2013136823A1 - Led点灯装置 - Google Patents
Led点灯装置 Download PDFInfo
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- WO2013136823A1 WO2013136823A1 PCT/JP2013/050238 JP2013050238W WO2013136823A1 WO 2013136823 A1 WO2013136823 A1 WO 2013136823A1 JP 2013050238 W JP2013050238 W JP 2013050238W WO 2013136823 A1 WO2013136823 A1 WO 2013136823A1
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- bus voltage
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- 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
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/10—Controlling the light source
-
- 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]
-
- 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
- H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
-
- 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
- H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
-
- 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
- H05B45/345—Current stabilisation; Maintaining constant current
-
- 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]
- H05B45/375—Switched mode power supply [SMPS] using buck 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
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
- H05B45/38—Switched mode power supply [SMPS] using boost topology
Definitions
- the present invention relates to an LED lighting device for lighting a semiconductor light source composed of a light emitting diode (LED) element.
- LED light emitting diode
- An LED (Light Emitting Diode) element as a semiconductor light source is widely used as a vehicular lamp, a traffic light, and an illumination lamp. For such applications, since the amount of light emitted from a single LED element is small, it is common to obtain a necessary amount of light by simultaneously lighting a plurality of LED elements.
- a converter is connected in series to an LED unit configured by connecting one or a plurality of LED elements in series, and a single LED is connected to both ends of the LED circuit block configured by the LED unit and the converter. DC power supply is connected.
- the converter includes a switch element, a diode, and a reactor.
- the current flowing through the LED unit is controlled at a constant current, and the LED unit is lit.
- a plurality of LED circuit blocks are connected in parallel to a DC power source, and the plurality of LED circuit blocks are operated by a single DC power source (for example, Patent Document 1).
- the LED circuit block is operated with a single constant voltage source, and the anode side of the diode is connected to the reference potential of the constant voltage source.
- the LED voltage which is the sum of the forward voltage drops of the LED elements, increases, and the voltage required to light the LED unit increases. End up.
- the present invention has been made to solve the above-described problem. Even when the voltage for driving the LED unit is increased, the withstand voltage of the switch elements constituting the converter can be lowered, and the reactor can be reduced.
- An object of the present invention is to provide a small and low-cost LED lighting device that can reduce current ripple.
- the LED lighting device is: A first bus having a first bus voltage; A second bus having a second bus voltage lower than the first bus voltage; A series connection body of a switch element, a reactor, and an LED unit in which one or a plurality of LED elements are connected in series, connected to the first bus, and a connection point between the switch element and the reactor, and the second bus An LED circuit block composed of a diode connected between A control circuit that controls the on / off of the switch element so that the LED current flowing through the LED unit is within a rated current range; When the LED unit is turned on, the voltage applied to both ends of the serial connection of the reactor and the LED unit is the first bus voltage when the switch element is on, and the first bus voltage when the switch element is off. And a voltage lower than the first bus voltage determined based on the second bus voltage.
- FIG. 7 is a diagram showing static characteristics of LED units constituting LED lighting devices according to Embodiments 1 to 6 of the present invention. It is a figure which shows the circuit structure of the LED lighting device of the reference example of this invention. It is a figure which shows each part waveform of the LED lighting device of the reference example of this invention. It is a figure which shows the circuit structure of the LED lighting device by Embodiment 2 of this invention. It is a figure which shows each part waveform of the LED lighting device by Embodiment 2 of this invention.
- FIG. 1 is a circuit configuration diagram showing an LED lighting device according to Embodiment 1 of the present invention
- FIG. 2 is a diagram showing waveforms of respective parts of the LED lighting device according to Embodiment 1 of the present invention.
- a constant voltage source 1 outputs a DC voltage that becomes a first bus voltage V1 through a first bus 100 and also outputs a DC voltage that becomes a second bus voltage V2 through a second bus 200, Supply the voltage necessary for lighting.
- a circuit constituting the constant voltage source 1 for example, a plurality of DC / DC converters or switching regulators such as an AC / DC converter can be used.
- the LED circuit block 3a1 includes a switching element Qa1, such as an FET (Field Effect Transistor), a reactor La1, an LED unit LEDa1 in which one or a plurality of LED elements are connected in series, and a diode Da1. Further, n LED circuit blocks having the same configuration as the LED circuit block 3a1 (n is a natural number of 1 or more) up to the LED circuit block 3an are connected in parallel to the first bus line 100 and the second bus line 200.
- a switching element Qa1 such as an FET (Field Effect Transistor)
- a reactor La1 an LED unit LEDa1 in which one or a plurality of LED elements are connected in series
- a diode Da1 n LED circuit blocks having the same configuration as the LED circuit block 3a1 (n is a natural number of 1 or more) up to the LED circuit block 3an are connected in parallel to the first bus line 100 and the second bus line 200.
- the first bus 100 of the constant voltage source 1 is connected to the first end of the switch element Qa1.
- the cathode terminal of the diode Da1 and the first end of the reactor La1 are connected to the second end of the switching element Qa1.
- the anode terminal of the diode Da1 is connected to the second bus 200.
- the second end of the reactor La1 is connected to the anode side terminal of the LED unit LEDa1 configured by connecting one or a plurality of LED elements in series.
- the cathode side terminal of the LED unit LEDa1 is connected to the reference potential of the constant voltage source 1.
- the control circuit 2 detects the LED current I LED flowing through the LED units (LEDa1 ⁇ LEDan), each LED current I LED is turned on and off control of the switch elements (Qa1 ⁇ Qan) such that the rated current range Constant current control is performed.
- the LED current I LED is detected by, for example, a shunt resistor inserted between the LED units (LEDa1 to LEDan) and the reference potential, as disclosed in the prior art, and the current flows. This can be realized by detecting a voltage drop.
- reference numerals 11a1 to 11an denote detection of each LED current.
- control circuit 2 detects the first bus voltage V1 and the second bus voltage V2, and performs voltage control of the first bus voltage V1 and the second bus voltage V2 so as to satisfy the conditions described later.
- 101 and 201 indicate detection of the first bus voltage V1 and the second bus voltage V2
- 20 indicates voltage control of the constant voltage source 1 by the control circuit 2.
- the first bus voltage V1 and the second bus voltage V2 may not be controlled by the control circuit 2 but may be set in advance by the constant voltage source 1 so as to satisfy the conditions described later.
- the “gate signal” is a signal for turning on and off the switch elements (Qa1 to Qan), and is output from the control circuit 2 to each switch element (Qa1 to Qan).
- LED voltage V LED is a voltage applied to both ends of each LED unit (LEDa1 to LEDan) when a rated current is passed through each LED unit (LEDa1 to LEDan) to light them.
- This “LED voltage V LED ” is a total sum of forward voltage drops of the LED elements constituting each LED unit (LEDa1 to LEDan), and the forward voltage drop varies among the LED elements.
- the LED voltage V LED also varies from LED unit to LED unit.
- FIG. 3 shows the relationship among V LED_max , V LED_min , and V LED_f with the static characteristics of the LED.
- the LED lighting device when the LED units (LEDa1 to LEDan) are turned on, the first bus voltage V1, the second bus voltage V2, and the LED voltage V LED are: V2 ⁇ V LED_min and V LED_max ⁇ V1 (1) A range of the first bus voltage V1, the second bus voltage V2, and the LED voltage V LED is set so as to satisfy the relationship. By setting in this way, the LED lighting device operates as described below. Since the operation of each LED circuit block (3a1 to 3an) is basically the same, the LED circuit block 3a1 will be described here as an example.
- the control circuit 2 turns on the gate signal of the switch element Qa1 again and turns on the switch element Qa1. Thereafter, the series of operations described above are repeated, the LED voltage V LED is always applied to both ends of the LED unit LEDa1, and the LED current in the rated current range continues to flow, and the LED unit LEDa1 is kept on. The same operation is performed for the other LED circuit blocks.
- FIG. 4 is a circuit configuration diagram illustrating an LED lighting device according to a reference example
- FIG. 5 is a diagram illustrating waveforms of respective parts of the LED lighting device according to the reference example of FIG.
- FIGS. 4 and 5 those having the same functions as those in FIGS. 1 and 2 are described by changing only the same symbols or subscripts.
- the first point is that the output voltage of the constant voltage source 4 of the LED lighting device of the reference example is only one kind of the first bus voltage V1, and the second point is the diode (Db1 to Dbn) of the LED lighting device of the reference example.
- the anode terminal is connected to the reference potential of the constant voltage source 4.
- the control circuit 5 detects the LED current flowing through the LED unit LEDb1, and performs on / off control of the switch element Qb1 so that the LED current is within the rated current range, thereby performing constant current control.
- the LED lighting device of such a reference example when the constant current control as described above is performed and the LED units (LEDb1 to LEDbn) are turned on, the voltage across each LED unit (LEDb1 to LEDbn) becomes the LED voltage V LED .
- the first bus voltage V1 is applied to both ends of the switching elements (Qb1 to Qbn) and both ends of the reactors (Lb1 to Lbn).
- the LED lighting device according to the first embodiment of the present invention has the voltage across the switching elements (Qa1 to Qan) and the reactors (La1 to Lan) as compared with the LED lighting device of the reference example. Can be reduced by the amount corresponding to the second bus voltage V2.
- the first bus voltage V1, the second bus voltage V2, and the LED voltage V LED are V2 ⁇ V LED_min and V LED_max ⁇ V1 (1)
- the switch element and the reactor are more effective than the LED lighting device of the conventional device including the reference example.
- the applied voltage can be reduced.
- An LED lighting device can be provided.
- the switch elements when it is desired to turn off the LED units (LEDa1 to LEDan), the switch elements (Qa1 to Qan) are turned off, and further, V2 ⁇ VLED_f is set.
- the two-bus voltage V2 may be set.
- the on / off control of the switch elements (Qa1 to Qan) by the control circuit 2 is performed by setting an upper limit and a lower limit on the LED current as described above, and turning on and off the switch elements (Qa1 to Qan) each time the upper limit and the lower limit are reached.
- a capacitor may be inserted in parallel for each LED unit (LEDa1 to LEDan) to reduce the ripple of current flowing through the LED unit (LEDa1 to LEDan).
- FIG. 6 is a diagram showing a circuit configuration of an LED lighting device according to Embodiment 2 of the present invention.
- FIG. 7 is a diagram showing waveforms of respective parts of the LED lighting device according to Embodiment 2 of the present invention.
- connection order of the elements constituting the LED circuit blocks (3c1 to 3cn) and the polarity of the diodes (Dc1 to Dcn) are different from the circuit configuration of the first embodiment. Since the LED circuit blocks (3c1 to 3cn) have the same configuration, the connection of the components will be described by taking the LED circuit block 3c1 as an example.
- the constant voltage source 1 outputs a DC voltage that is the first bus voltage V1 through the first bus 100 and a DC voltage that is the second bus voltage V2 through the second bus voltage 200.
- a voltage necessary for lighting the element is supplied.
- the 1st bus-line 100 is connected to the anode side terminal of LED unit LEDc1.
- the cathode side terminal of the LED unit LEDc1 is connected to the first end of the reactor Lc1, and the second end of the reactor Lc1 is connected to the first end of the switching element Qc1.
- the second end of the switch element Qc1 is connected to the reference potential of the constant voltage source 1.
- the anode terminal of the diode Dc1 is connected to the connection point between the reactor Lc1 and the switch element Qc1, and the cathode terminal is connected to the second bus 200.
- This second bus 200 enables current sinking.
- the control circuit 6 detects each LED current I LED flowing through each LED unit (LEDc1 to LEDcn), and controls each switch element (Qc1 to Qcn) to turn on and off so that the LED current I LED is in the rated current range. Perform constant current control.
- the LED current is detected by detecting the current on the anode side or the cathode side of the LED units (LEDc1 to LEDcn). For example, an amplifier that supports current detection on the high voltage side can be used.
- reference numerals 11c1 to 11cn denote LED current detection.
- control circuit 2 detects the first bus voltage V1 and the second bus voltage V2, and performs voltage control of the first bus voltage V1 and the second bus voltage V2 so as to satisfy the conditions described later.
- reference numerals 101 and 201 denote detection of the first bus voltage V1 and the second bus voltage V2
- reference numeral 60 denotes voltage control of the constant voltage source 1 by the control circuit 6.
- the first bus voltage V1 and the second bus voltage V2 may not be controlled by the control circuit 2 but may be set in advance by the constant voltage source 1 so as to satisfy the conditions described later.
- the LED lighting device when the LED units (LEDc1 to LEDcn) are turned on, the first bus voltage V1, the second bus voltage V2, and the LED voltage V LED described above are: V1-V2 ⁇ V LED_min and V LED_max ⁇ V1 (2) A range of the first bus voltage V1, the second bus voltage V2, or the LED voltage V LED is set so as to satisfy the following relationship. By setting in this way, the LED lighting device operates as described below. Since the operation of each LED circuit block (3c1 to 3cn) is basically the same, the LED circuit block 3c1 will be described as an example here.
- the control circuit 6 turns on the gate signal of the switch element Qc1 again and turns on the switch element Qc1. Thereafter, the series of operations described above is repeated, and the LED voltage V LED is always applied to both ends of the LED unit LEDc1, and the LED current in the rated current range continues to flow, and the LED unit LEDc1 is continuously lit. The same operation is performed for the other LED circuit blocks.
- the first bus voltage V1, the second bus voltage V2, and the LED voltage V LED are V1-V2 ⁇ V LED_min and V LED_max ⁇ V1 (2)
- the switch element than the LED lighting device of the reference example described in FIG. 4 and FIG. the voltage applied to the reactor can be reduced to the second bus voltage V2 ( ⁇ V1). Therefore, a switching element having a lower withstand voltage than that of the conventional device including the reference examples of FIGS.
- the switch elements when it is desired to turn off the LED units (LEDc1 to LEDcn), the switch elements (Qc1 to Qcn) are turned off, and further, V1 ⁇ V2 ⁇ VLED_f is satisfied .
- the first bus voltage V1 or the second bus voltage V2 may be set.
- FIG. 8 is a circuit configuration diagram of an LED lighting device according to Embodiment 3 of the present invention.
- components having the same functions as those in the first embodiment are described by changing only the same symbols or subscripts.
- the LED lighting device according to the third embodiment is intended for in-vehicle use, and includes a constant voltage source 7, the LED circuit blocks (3a1 to 3an) described in the first embodiment, and a control circuit 11. These basic configurations are the same as those of the LED lighting device according to the first embodiment, and the constant voltage source 7 specifically shows the constant voltage source 1 of the first embodiment.
- the control circuit 11 is obtained by adding the control function of the converter constituting the constant voltage source 7 to the function of the control circuit 2 of the first embodiment. Therefore, the voltage conditions for turning on and off the LED units (LEDa1 to LEDan) of the LED lighting device according to the third embodiment and the waveforms of the respective parts during operation are the same as those of the LED lighting device according to the first embodiment. Therefore, the description of the operation is omitted, and the configuration of the constant voltage source 7 and the function of the control circuit 11 will be described.
- V2 ⁇ V LED_min and V LED_max described in the LED lighting device according to the first embodiment, from the battery voltage VB output from the battery 8.
- V1 The first bus voltage V1 and the second bus voltage V2 must be generated.
- the first converter 10 is provided on the output side of the battery 8 to boost the battery voltage VB and provide the first bus voltage V1 higher than VLED_max .
- the first converter 10 may perform a step-down operation or the first converter 10 itself may be omitted.
- the second bus voltage V2 is generated by a second converter 9 provided between the anode terminals of the diodes (Da1 to Dan) and the output terminal of the battery 8.
- the second converter 9 receives the battery voltage VB side as input, and allows current to flow out to the second bus 200 side.
- the control circuit 11 detects the voltage of the first bus voltage V1 and the second bus voltage V2, and the first converter 10 and the second converter so that these voltages satisfy the voltage condition of the first embodiment. 9 is controlled.
- 11 ⁇ / b> A indicates voltage control of the first converter 10 by the control circuit 11
- 11 ⁇ / b> B indicates voltage control of the second converter 9 by the control circuit 11.
- the control circuit 11 also performs constant current control of the LED current described in the first embodiment.
- the voltage detection means for the first bus voltage V1 and the second bus voltage V2 can be used, for example, by connecting a voltage dividing resistor between each output terminal and the reference voltage. Further, for example, a switching regulator or the like can be used for the first converter 10 and the second converter 9.
- the constant voltage source has the battery, the first converter, and the second converter, and the control circuit has the output of the first converter as the first. Since the output of the second converter is controlled to be the second bus voltage V2 with respect to the bus voltage V1, the same effect as that of the LED lighting device of the first embodiment can be obtained particularly for in-vehicle use. .
- FIG. 9 is a circuit configuration diagram of an LED lighting device according to Embodiment 4 of the present invention.
- components having the same functions as those in the above-described embodiment are described by changing only the same symbols or subscripts.
- the LED lighting device according to the fourth embodiment is intended for in-vehicle use, and includes a constant voltage source 7, the LED circuit blocks (3c1 to 3cn) described in the second embodiment, and a control circuit 12. These basic configurations are the same as those of the LED lighting device according to the second embodiment, and the constant voltage source 7 specifically shows the constant voltage source 1 of the second embodiment.
- the control circuit 12 is obtained by adding the control function of the converter constituting the constant voltage source 7 to the function of the control circuit 6 of the second embodiment. Therefore, the voltage conditions for turning on and off the LED units (LEDc1 to LEDcn) of the LED lighting device according to the fourth embodiment and the waveforms of the respective parts during operation are the same as those of the LED lighting device according to the second embodiment. Therefore, explanation of their operations is omitted, and functions of the constant voltage source 7 and the control circuit 12 are described.
- the LED lighting device according to the fourth embodiment of the present invention is supposed to be used in a vehicle, V1 ⁇ V2 ⁇ V LED_min and V described in the LED lighting device according to the second embodiment, from the battery voltage VB output from the battery 8.
- LED_max ⁇ V1 (2)
- the first bus voltage V1 and the second bus voltage V2 must be generated.
- the LED units (LEDc1 to LEDcn) cannot be turned on. Therefore, the first converter 10 is provided on the output side of the battery 8 to boost the battery voltage VB and provide the first bus voltage V1 higher than VLED_max .
- the first converter 10 may perform a step-down operation or the first converter 10 itself may be omitted.
- the second bus voltage V2 is generated by a second converter 9 provided between the cathode terminals of the diodes (Dc1 to Dcn) and the output terminal of the battery 8.
- the second converter 9 here allows the current to be drawn from the second bus 200 side by using the second bus 200 side as an input and the battery voltage VB as an output.
- the LED lighting device has the battery, the first converter and the second converter connected to the output terminal of the battery as the constant voltage source, and the control circuit is Since the output of the first converter is controlled to the first bus voltage V1, and the output of the second converter is controlled to the second bus voltage V2, the LED lighting of the second embodiment is turned on particularly for in-vehicle use. The same effect as the device can be obtained.
- FIG. 10 is a circuit configuration diagram of an LED lighting device according to Embodiment 5 of the present invention.
- the circuit configuration of the fifth embodiment shown in FIG. 10 is obtained by omitting the second converter 9 from the LED lighting device of the third embodiment shown in FIG. 8, and the control circuit 14 has the first bus voltage V1. Only control and constant current control are performed. Since the circuit operation of FIG. 10 is the same as that of the third embodiment, the description thereof is omitted.
- FIG. 11 is a circuit configuration diagram of an LED lighting device according to Embodiment 6 of the present invention.
- the circuit configuration of the sixth embodiment shown in FIG. 11 is obtained by omitting the second converter 9 from the LED lighting device of the fourth embodiment shown in FIG. 9, and accordingly, the control circuit 16 has a first bus. Only control of voltage V1 and constant current control are performed. Since the circuit operation of FIG. 11 is the same as that of the fourth embodiment, description thereof is omitted.
- the second bus voltage V2 is fixed to the battery voltage VB, the effect of lowering the breakdown voltage of the constituent elements cannot be obtained as much as the LED lighting device according to the fourth embodiment.
- the circuit can be made smaller and the control circuit simplified than in the fourth embodiment.
- FIG. 12 is a circuit configuration diagram of an LED lighting device according to Embodiment 7 of the present invention.
- the circuit configuration of the seventh embodiment shown in FIG. 12 is not a plurality of LED circuit blocks arranged in parallel in the LED lighting device of the first embodiment shown in FIG. 1, but only one LED circuit block 3a1. ing. Since the operation of the LED lighting device according to the seventh embodiment is basically the same as the operation of the LED lighting device according to the first embodiment, detailed description thereof is omitted. However, as shown in the static characteristic diagram of the LED unit shown in FIG.
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Abstract
Description
従来のLED点灯装置では、1個又は複数個のLED素子を直列接続させて構成したLEDユニットに、コンバータを直列接続し、更にLEDユニットとコンバータで構成されたLED回路ブロックの両端に、単一の直流電源を接続している。コンバータはスイッチ素子、ダイオード、リアクトルから構成されており、スイッチ素子をオンオフすることにより、LEDユニットに流れる電流を定電流制御して、LEDユニットを点灯させている。また、このLED回路ブロックを直流電源に対して複数並列接続して、複数のLED回路ブロックを単一の直流電源で動作させている(例えば特許文献1)。
第1母線電圧を有する第1母線と、
上記第1母線電圧より低い第2母線電圧を有する第2母線と、
上記第1母線に接続される、スイッチ素子、リアクトル、及び1個または複数のLED素子を直列接続したLEDユニット、の直列接続体、並びに上記スイッチ素子と上記リアクトルの接続点と上記第2母線との間に接続したダイオード、で構成されるLED回路ブロックと、
上記LEDユニットに流れるLED電流が定格電流範囲内となるように、上記スイッチ素子をオンオフ制御する制御回路とを備え、
上記LEDユニットの点灯時に、上記リアクトルと上記LEDユニットとの直列接続の両端に印加される電圧が、上記スイッチ素子がオン時に上記第1母線電圧に、上記スイッチ素子がオフ時に上記第1母線電圧と上記第2母線電圧に基づいて定まる上記第1母線電圧より低い電圧になるようにする。
以下、この発明の実施の形態1によるLED点灯装置を図に基づいて説明する。図1はこの発明の実施の形態1によるLED点灯装置を示す回路構成図、図2はこの発明の実施の形態1のLED点灯装置の各部の波形を示す図である。
この発明の実施の形態1によるLED点灯装置は、LEDユニット(LEDa1~LEDan)点灯時に、第1母線電圧V1と、第2母線電圧V2と、LED電圧VLEDが、
V2<VLED_min、かつ VLED_max<V1 ・・・(1)
の関係となるように、第1母線電圧V1、第2母線電圧V2、LED電圧VLEDの範囲を設定することを特徴としている。このように設定することによって、LED点灯装置は下記に述べるように動作する。なお、各LED回路ブロック(3a1~3an)の動作は基本的に同じなので、ここではLED回路ブロック3a1を例に説明する。
これに対して上記説明したように、この発明の実施の形態1によるLED点灯装置は、スイッチ素子(Qa1~Qan)、及びリアクトル(La1~Lan)の両端電圧を、参考例のLED点灯装置よりも第2母線電圧V2の分だけ小さくすることができる。
V2<VLED_min、かつ VLED_max<V1 ・・・(1)
の関係になるように、第1母線電圧V1、第2母線電圧V2、またはLED電圧VLEDの範囲を設定することにより、参考例を含めた従来装置のLED点灯装置よりもスイッチ素子とリアクトルに印加される電圧を小さくすることができる。したがって、参考例を含めた従来装置よりも低耐圧のスイッチ素子が利用できるとともに、LED電流(=リアクトル電流)の許容リップルを同等とすれば、リアクトルも小型化することができ、小型かつ低コストなLED点灯装置を提供することができる。
次に、この発明の実施の形態2によるLED点灯装置を図に基づいて説明する。図6はこの発明の実施の形態2によるLED点灯装置の回路構成を示す図である。図7はこの発明の実施の形態2によるLED点灯装置の各部の波形を示す図である。
この発明の実施の形態2によるLED点灯装置は、LEDユニット(LEDc1~LEDcn)点灯時に、第1母線電圧V1と、第2母線電圧V2と、前述したLED電圧VLEDが、
V1-V2<VLED_min かつ VLED_max<V1 ・・・(2)
の関係となるように、第1母線電圧V1、第2母線電圧V2、またはLED電圧VLEDの範囲を設定することを特徴としている。このように設定することによって、LED点灯装置は下記に述べるように動作する。なお、各LED回路ブロック(3c1~3cn)の動作は基本的に同じなので、ここではLED回路ブロック3c1を例に説明する。
V1-V2<VLED_min かつ VLED_max<V1 ・・・(2)
の関係になるように、第1母線電圧V1、第2母線電圧V2、またはLED電圧VLEDの範囲を設定することにより、図4及び図5で説明した参考例のLED点灯装置よりもスイッチ素子とリアクトルに印加される電圧を第2母線電圧V2(<V1)まで小さくすることができる。したがって、図4及び図5の参考例を含めた従来装置よりも低耐圧のスイッチ素子が利用できるとともに、LED電流(=リアクトル電流)の許容リップルを同等とすれば、リアクトルも小型化することができ、小型かつ低コストなLED点灯装置を提供できる。また、スイッチ素子(Qc1~Qcn)がオフしている期間は、エネルギーが回生されるので、従来よりも高効率なLED点灯装置を提供することができる。
次に、この発明の実施の形態3によるLED点灯装置を図に基づいて説明する。図8はこの発明の実施の形態3によるLED点灯装置の回路構成図である。図8において、実施の形態1(図1)の構成要素と共通する機能を有するものは、同じ記号、または添え字のみ変更して記している。
V2<VLED_min、かつ VLED_max<V1 ・・・(1)
の電圧の関係にある第1母線電圧V1と、第2母線電圧V2を生成しなければならない。
ここで、LEDユニット(LEDa1~LEDan)を構成するLED素子の直列接続数が多く、バッテリ電圧VB<LED電圧VLED_maxとなると、LEDユニット(LEDa1~LEDan)を点灯することができない。そこで、バッテリ8の出力側に第1のコンバータ10を設け、バッテリ電圧VBを昇圧し、VLED_maxよりも高い第1母線電圧V1を提供する。バッテリ電圧VBがLED電圧VLED_maxよりも高い場合は、第1のコンバータ10は降圧動作を行うか、あるいは第1のコンバータ10自体を省略してもよい。また、第2母線電圧V2は、ダイオード(Da1~Dan)のアノード端子とバッテリ8の出力端子の間に設けた第2のコンバータ9により生成する。ここでの第2のコンバータ9は、バッテリ電圧VB側を入力とし、第2母線200側に電流の流れ出しを可能とする。
次に、この発明の実施の形態4によるLED点灯装置を図に基づいて説明する。図9はこの発明の実施の形態4によるLED点灯装置の回路構成図である。図9において、上記実施の形態における構成要素と共通する機能を有するものは、同じ記号、または添え字のみ変更して記している。
V1-V2<VLED_min かつ VLED_max<V1 ・・・(2)
の電圧の関係にある第1母線電圧V1と、第2母線電圧V2を生成しなければならない。
ここで、LEDユニット(LEDc1~LEDcn)を構成するLED素子の直列接続数が多く、バッテリ電圧VB<LED電圧VLED_maxとなると、LEDユニット(LEDc1~LEDcn)を点灯することができない。そこで、バッテリ8の出力側に第1のコンバータ10を設け、バッテリ電圧VBを昇圧し、VLED_maxよりも高い第1母線電圧V1を提供する。バッテリ電圧VBがLED電圧VLED_maxよりも高い場合は、第1のコンバータ10は降圧動作を行うか、あるいは第1のコンバータ10自体を省略してもよい。また、第2母線電圧V2は、ダイオード(Dc1~Dcn)のカソード端子とバッテリ8の出力端子の間に設けた第2のコンバータ9により生成する。また、ここでの第2のコンバータ9は、第2母線200側を入力、バッテリ電圧VBを出力として、第2母線200側からの電流の吸い込みを可能とする。
次に、この発明の実施の形態5によるLED点灯装置を図に基づいて説明する。図10はこの発明の実施の形態5によるLED点灯装置の回路構成図である。図10に示す実施の形態5の回路構成は、図8に示す実施の形態3のLED点灯装置から、第2のコンバータ9を省略したものであり、制御回路14は、第1母線電圧V1の制御と定電流制御のみを行う。図10の回路動作については実施の形態3と同じなので、説明を省略する。
次に、この発明の実施の形態6によるLED点灯装置を図に基づいて説明する。図11はこの発明の実施の形態6によるLED点灯装置の回路構成図である。図11に示す実施の形態6の回路構成は、図9に示す実施の形態4のLED点灯装置から、第2のコンバータ9を省略したものであり、それに伴い、制御回路16は、第1母線電圧V1の制御と定電流制御のみを行う。図11の回路動作については実施の形態4と同じなので、説明を省略する。
次に、この発明の実施の形態7によるLED点灯装置を図に基づいて説明する。図12はこの発明の実施の形態7によるLED点灯装置の回路構成図である。図12に示す実施の形態7の回路構成は、図1に示す実施の形態1のLED点灯装置においてLED回路ブロックが複数個並列配置されているのではなくLED回路ブロック3a1が1個のみ配置されている。実施の形態7によるLED点灯装置の動作は、基本的に実施の形態1によるLED点灯装置の動作と同様であるので詳細な説明は省略する。ただし、図13に示すLEDユニットの静特性図のように、LEDユニットが複数個でなく1個のため、LED電圧はバラツキを持たず、LED電圧はLEDユニット(LEDa1)の電圧VLEDのみとなる。そのため、LED点灯時の第1母線電圧V1と、第2母線電圧V2と、LED電圧VLEDは、
上記式(1)において、VLED=VLED_min=VLED_maxとして、
V2<VLED<V1 ・・・(3)
の関係になるように設定する。
上記式(2)において、VLED=VLED_min=VLED_maxとして、
V1-V2<VLED<V1 ・・・(3)
の関係になるように設定する。
その他の実施の形態3~6においても上記と同様に考えることができる。
Claims (10)
- 第1母線電圧を有する第1母線と、
上記第1母線電圧より低い第2母線電圧を有する第2母線と、
上記第1母線に接続される、スイッチ素子、リアクトル、及び1個または複数のLED素子を直列接続したLEDユニット、の直列接続体、並びに上記スイッチ素子と上記リアクトルの接続点と上記第2母線との間に接続したダイオード、で構成されるLED回路ブロックと、
上記LEDユニットに流れるLED電流が定格電流範囲内となるように、上記スイッチ素子をオンオフ制御する制御回路とを備え、
上記LEDユニットの点灯時に、上記リアクトルと上記LEDユニットとの直列接続の両端に印加される電圧が、上記スイッチ素子がオン時に上記第1母線電圧、上記スイッチ素子がオフ時に上記第1母線電圧と上記第2母線電圧に基づいて定まる上記第1母線電圧より低い電圧になるようにするLED点灯装置。 - 上記第1母線及び上記第2母線に対して上記LED回路ブロックが複数個並列接続され、上記各LED回路ブロックは、上記第1母線に、上記スイッチ素子、上記リアクトル、及び上記LEDユニットの順番で直列に接続するとともに、上記ダイオードはアノード側を上記第2母線に接続し、カソード側を上記スイッチ素子と上記リアクトルの接続点に接続した構成である請求項1に記載のLED点灯装置。
- 上記各LEDユニットの点灯時は、上記第1母線電圧V1と、上記第2母線電圧V2と、上記各LEDユニットに印加されるLED電圧のうち最も高い電圧VLED_max及び最も低い電圧VLED_minとの関係が、
V2<VLED_min かつ VLED_max<V1 ・・・(1)
となるように上記第1母線電圧V1、上記第2母線電圧V2を設定する請求項2に記載のLED点灯装置。 - 上記各LEDユニットの消灯時は、上記各スイッチ素子をオフし、かつ上記第2母線電圧V2と、上記各LEDユニットが実質的に消灯とみなせる程度にまで電流が小さくなるときのLED電圧VLED_fとの関係が、
V2≦VLED_f
となるように、上記第2母線電圧V2を設定する請求項2又は請求項3に記載のLED点灯装置。 - 上記第1母線及び上記第2母線に対して上記LED回路ブロックが複数個並列接続され、上記各LED回路ブロックは、上記第1母線に、上記LEDユニット、上記リアクトル、及び上記スイッチ素子の順番で直列に接続するとともに、上記ダイオードはカソード側を上記第2母線に接続し、アノード側を上記スイッチ素子と上記リアクトルの接続点に接続した構成である請求項1に記載のLED点灯装置。
- 上記各LEDユニットの点灯時は、上記第1母線電圧V1と、上記第2母線電圧V2と、上記各LEDユニットに印加されるLED電圧のうち最も高い電圧VLED_max及び最も低い電圧VLED_minとの関係が、
V1-V2<VLED_min かつ VLED_max<V1 ・・・(2)
となるように上記第1母線電圧V1、上記第2母線電圧V2を設定する請求項5に記載のLED点灯装置。 - 上記各LEDユニットの消灯時は、上記各スイッチ素子をオフし、かつ上記第1母線電圧V1と、上記第2母線電圧V2と、上記各LEDユニットが実質的に消灯とみなせる程度にまで電流が小さくなるときのLED電圧VLED_fとの関係が、
V1-V2≦VLED_f
となるように、上記第1母線電圧V1、上記第2母線電圧V2を設定する請求項5又は請求項6に記載のLED点灯装置。 - 上記第1母線及び上記第2母線は定電圧源に接続されており、上記制御回路は、上記第1母線電圧又は上記第2母線電圧を上記設定値になるように上記定電圧源の上記第1母線電圧又は上記第2母線電圧を制御する請求項1から請求項7のいずれか1項に記載のLED点灯装置。
- バッテリの出力端子にそれぞれ接続された第1のコンバータと第2のコンバータを備え、上記第1のコンバータは上記第1母線に接続され、上記第2のコンバータは上記第2母線に接続され、上記制御回路は、上記第1のコンバータの出力が上記第1母線電圧に、上記第2のコンバータの出力が上記第2母線電圧になるように制御する請求項1から請求項7のいずれか1項に記載のLED点灯装置。
- バッテリの出力端子に接続された第1のコンバータを備え、上記第1のコンバータは上記第1母線に接続され、上記バッテリの出力電圧が上記第2母線電圧となり、上記制御回路は、上記第1のコンバータの出力が上記第1母線電圧になるように制御する請求項1から請求項7のいずれか1項に記載のLED点灯装置。
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