JP2018196249A - Illumination instrument and illumination system - Google Patents

Abstract

To provide an illumination instrument capable of suppressing a flicker of light.SOLUTION: An illumination instrument 8 comprises: a lighting device 2 connected to a DC power supply 6; and an LED light source 4. The lighting device 2 comprises a back converter circuit 10. The LED light source 4 lights up using power output by the back converter circuit 10. The LED light source 4 may be an inorganic LED light source or an OLED, i.e. organic EL. The lighting device 2 comprises an input terminal block CN1, a backflow prevention diode D1, an input side capacitor C1, the back converter circuit 10, a constant current control circuit 14 and an output terminal block CN2. The input side capacitor C1 and the backflow prevention diode D1 configures a series circuit connected in parallel to a positive input terminal and negative input terminal of the input terminal block CN1. An anode of the backflow prevention diode D1 is connected to the positive input terminal; a cathode of the backflow prevention diode D1 is connected to the input side capacitor C1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting fixture and a lighting system.

  With the widespread use of solar power generation systems and storage batteries, energy sources that handle DC voltage are increasing. On the other hand, the use of LEDs in lighting fixtures has progressed, and for example, as disclosed in Japanese Patent Application Laid-Open No. 2013-70583, a technique for lighting LED lighting using a DC power source is known.

JP 2013-70583 A

  When the output of the DC power supply fluctuates, the DC voltage input to the lighting fixture may fluctuate. For example, in a solar power generation system, the DC voltage input to a lighting fixture falls momentarily when the power changes from solar power generation to power supply by a storage battery at sunset. When such a voltage fluctuation occurs in the DC power supply, the LED light source becomes dark for a moment, causing a problem that light flickers.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a lighting fixture and a lighting system that can suppress flickering of light.

  The luminaire according to the present invention is charged by applying an input terminal portion having a positive input terminal and a negative input terminal, a diode having an anode connected to the positive input terminal, and a voltage of the cathode of the diode at one end. A power conversion circuit that receives DC power from a connection point between the input-side capacitor, the cathode of the diode, and the one end of the input-side capacitor, converts the DC power, and is lit with power output from the power conversion circuit The input terminal unit and the power conversion circuit are connected without interposing another power conversion circuit therebetween.

  An illumination system according to the present invention includes a DC power supply, a positive input terminal and a negative input terminal, an input terminal connected to the DC power supply, a diode having an anode connected to the positive input terminal, and one end of the diode A power converter that receives DC power from a connection point between an input-side capacitor that is charged by applying a voltage of a cathode of the diode and the cathode of the diode and the one end of the input-side capacitor, and converts the DC power A light emitting element that is lit with power output from the power conversion circuit, and the input terminal portion and the power conversion circuit are connected without interposing another power conversion circuit therebetween. .

  According to the present invention, even when the DC voltage of the DC power supply fluctuates, the fluctuation of the voltage input to the power conversion circuit by the input side capacitor and the diode can be suppressed, so that the flickering of light can be suppressed.

It is a circuit diagram which shows the lighting fixture and lighting system concerning Embodiment 1 of this invention. It is a time chart which shows operation | movement of the lighting fixture and lighting system concerning Embodiment 1 of this invention.

  FIG. 1 is a circuit diagram showing a lighting fixture 8 and a lighting system 1 according to a first embodiment of the present invention. The lighting system 1 includes a DC power supply 6 and a lighting fixture 8 that receives DC power from the DC power supply 6. The DC power source 6 is a DC power supply system, and specifically, a solar power generation system including a solar battery, a storage battery, and the like. The lighting fixture 8 includes a lighting device 2 connected to a DC power source 6 and an LED light source 4. The lighting device 2 includes a buck converter circuit 10. The LED light source 4 is lit with the power output from the buck converter circuit 10. The light emitting element constituting the LED light source 4 may be an inorganic LED or an OLED, that is, an organic EL. The lighting device 2 includes an input terminal block CN1, a backflow prevention diode D1, an input side capacitor C1, a buck converter circuit 10, a constant current control circuit 14, and an output terminal block CN2.

  The input terminal block CN1 has a positive input terminal and a negative input terminal. The input terminal block CN1 is connected to the DC power source 6. The anode of the backflow prevention diode D1 is connected to the positive input terminal of the input terminal block CN1. A circuit ground, that is, a reference potential is applied to the negative input terminal of the input terminal block CN1.

  A series circuit composed of the backflow prevention diode D1 and the input side capacitor C1 is connected in parallel to the positive input terminal and the negative input terminal of the input terminal block CN1. The negative terminal of the input side capacitor C1 and the negative electrode of the DC power source 6 are connected to the circuit ground. The backflow prevention diode D1 is interposed between the positive input terminal and the input side capacitor C1. More specifically, in the lighting device 2 according to the embodiment, the anode of the backflow prevention diode D1 and the positive input terminal of the input terminal block CN1 are directly connected, and the cathode of the backflow prevention diode D1 and the positive electrode of the input side capacitor C1. The terminal is directly connected. DC power is input to the buck converter circuit 10 from the cathode of the backflow prevention diode D1. “Direct connection” means a connection without interposing other circuit elements.

  The buck converter circuit 10 includes a MOSFET Q1, a coil L1, a diode D2, and an output smoothing capacitor C2. The buck converter circuit 10 is interposed between the DC power source 6 and the LED light source 4. A connection point between the input side capacitor C1 and the drain of the MOSFET Q1 is connected to the cathode of the backflow prevention diode D1. The buck converter circuit 10 converts the DC power input from the cathode of the backflow prevention diode D1 and outputs it from the output terminal block CN2. The output voltage VDC of the DC power supply 6 is supplied to the buck converter circuit 10 through the backflow prevention diode D1. The input side capacitor C1 is also charged by the power from the cathode of the backflow prevention diode D1. A connection point between the cathode of the diode D2 and one end of the coil L1 is connected to the source of the MOSFET Q1. The other end of the coil L1 is connected to the positive terminal of the output smoothing capacitor C2. The anode of the diode D2 is also connected to the circuit ground.

  The LED light source 4 is connected in parallel with the output smoothing capacitor C2 via the output terminal block CN2. The output smoothing capacitor C2 is connected in parallel with the output terminal block CN2. The capacity of the input side capacitor C1 is preferably larger than the capacity of the output smoothing capacitor C2.

  The constant current control circuit 14 includes a control IC 12, a secondary winding L2 of the coil L1, a capacitor C4, resistors R1 to R3, a comparator OP1, and a constant voltage source Vref. One end of a resistor R1 is connected to the negative terminal of the output smoothing capacitor C2. The other end of the resistor R1 is connected to circuit ground. One end of the resistor R2 is connected to the positive terminal of the output smoothing capacitor C2, and the other end of the resistor R2 is connected to the other end of the resistor R1.

  The control IC 12 is a Vg terminal connected to the gate of the MOSFET Q1, a control power supply Vcc terminal for obtaining the operating power of the control IC 12, an on-time detection terminal det for detecting the on-time of the MOSFET Q1, and a zero-cross detection terminal. zcd terminal. A capacitor C4 is connected to the on-time detection terminal det in order to stabilize the negative terminal voltage. One end of the resistor R3 is connected to the secondary winding L2, and the other end of the resistor R3 is connected to the zcd terminal. The resistor R3 limits the current of the secondary winding L2 and supplies it to the zcd terminal.

  The connection point between the resistor R1 and the negative terminal of the output smoothing capacitor C2 is connected to the negative terminal of the comparator OP1. A constant voltage source Vref is applied to the plus terminal of the comparator OP1. The output terminal of the comparator OP1 is connected to the on-time detection terminal det of the control IC 12.

  The constant current control circuit 14 operates the buck converter circuit 10 at a constant current. The buck converter circuit 10 outputs a constant current by performing a so-called critical operation. When the MOSFET Q1 is turned on, current is supplied from the DC power source 6 and the input side capacitor C1 via the coil L1. When MOSFET Q1 is turned off, the energy stored in coil L1 is released when MOSFET Q1 is turned on. The output smoothing capacitor C2 smoothes the current flowing through the coil L1. The smoothed current is supplied to the LED light source 4.

  A voltage corresponding to the current flowing through the output smoothing capacitor C2 and the LED light source 4 is generated in the resistor R1. The resistor R1 converts an average current flowing through the LED light source 4 into a voltage. The voltage generated in the resistor R1 is detected at the negative terminal of the comparator OP1 and compared with the voltage of the constant voltage source Vref. The output signal of the comparator OP1 is input to the on-time detection terminal det. The control IC 12 controls the switching operation of the MOSFET Q1 based on the signal input to the on-time detection terminal det. The comparator OP1 changes the output voltage according to the difference between the voltage detected by the resistor R1 and the voltage of the constant voltage source Vref. By controlling the ON time of the control IC 12 in accordance with the output voltage of the comparator OP1, constant current control for making the LED current of the LED light source 4 constant is performed. The voltage of the secondary winding L2 is detected at the zcd terminal of the control IC 12. A critical operation is performed in which the MOSFET Q1 is turned off and energy is released from the coil L1, and the MOSFET Q1 is turned on again.

  In the lighting device 2 according to the embodiment, no other power conversion circuit such as a step-up chopper circuit is sandwiched between the input terminal block CN1 and the buck converter circuit 10. If the input terminal block CN1 and the buck converter circuit 10 are directly connected without the input-side capacitor C1 being provided, an instantaneous voltage drop of the DC power supply 6 is directly transmitted to the buck converter circuit 10. The light from the LED light source 4 flickers due to voltage fluctuation. In this regard, in the embodiment, stable power supply to the LED light source 4 can be performed by compensating for an instantaneous voltage drop of the DC power supply 6 by the input side capacitor C1. Further, the backflow prevention diode D1 prevents a current from flowing back from the input side capacitor C1 to the positive input terminal of the input terminal block CN1. With this backflow prevention function, it is possible to prevent the charge from being wastedly returned from the input side capacitor C1 to the DC power supply 6 side. When the output voltage VDC of the DC power supply 6 decreases, the backflow prevention diode D1 can prevent the charge from flowing back from the input side capacitor C1 and suddenly changing the voltage of the input side capacitor C1. As described above, according to the embodiment, even when there is a voltage fluctuation of the DC power supply 6, fluctuations in the voltage input to the buck converter circuit 10 are suppressed by the input side capacitor C1 and the backflow prevention diode D1. be able to. Therefore, even if the voltage of the DC power source 6 varies, the flickering of the light from the LED light source 4 can be suppressed.

  As a modification, a diode bridge may be used instead of the backflow prevention diode D1. The diode bridge is a rectifier circuit composed of a plurality of diodes, and one of the diodes has an anode connected to the positive input terminal and a cathode connected to the positive terminal of the input-side capacitor C1, similarly to the backflow prevention diode D1. However, the diode bridge has a demerit that the circuit efficiency deteriorates because the voltage drop occurs twice.

  FIG. 2 is a time chart showing operations of the lighting fixture 8 and the lighting system 1 according to the first embodiment of the present invention. FIG. 2 shows the operation of the lighting fixture 8 when the output voltage VDC of the DC power supply 6 is instantaneously reduced. For convenience of explanation, the LED current graph is enlarged in the Y-axis direction.

  First, at time t1, the output voltage VDC of the DC power supply 6 decreases. Next, at time t1 to t2, as the output voltage VDC of the DC power supply 6 decreases, the voltage of the input side capacitor C1 also decreases. While the voltage of the input side capacitor C1 is decreasing, the feedback control is not in time for the delay time of the feedback control of the comparator OP1, so that the LED current is decreased.

  Next, at times t2 to t3, the control IC 12 adjusts the ON period of the MOSFET Q1 to be longer based on the output voltage of the comparator OP1. Thereby, the control which suppresses the voltage fluctuation of the input side capacitor | condenser C1 and keeps LED current to a constant current is performed.

  Next, when the DC power supply 6 is restored at time t3, the DC power supply 6 outputs the original steady voltage. At time t3 to t4, since the DC power supply 6 returns to a steady state, the input side capacitor C1 is charged again. Similar to the times t1 to t2, the feedback control is not in time for the delay time of the feedback control of the comparator OP1 at the times t3 to t4. Therefore, although the DC power supply 6 has returned to a steady state, the on-time of the MOSFET Q1 is continuously adjusted longer.

  After time t3, the LED current becomes larger than a predetermined value. From time t4 to t5, the control IC 12 adjusts the ON time to be short based on the output voltage of the comparator OP1 in order to keep the LED current at a predetermined value. Next, at time t5, the input side capacitor C1 is charged to a steady value. At times t5 to t6, the ON time is sufficiently shortened, and the LED current returns to the steady value.

  According to the operation described above, it is possible to stably supply power to the LED light source 4 while compensating for an instantaneous voltage drop of the DC power supply 6 by the input side capacitor C1. Therefore, a change in the brightness of the lighting fixture 8 can be suppressed.

  In the embodiment, the buck converter circuit 10 is operated in the critical mode. However, the operation mode of the buck converter circuit 10 may be on-duty control with a fixed frequency. Further, a power conversion circuit other than the buck converter circuit 10 may be used, and the buck converter circuit 10 may be replaced with a step-up / step-down circuit such as a flyback circuit or a buck boost circuit. However, since the buck-boost circuit can output a DC voltage even if the input voltage is lower than the LED voltage, the circuit configuration of the embodiment is applied to the buck converter circuit 10 that cannot perform such a buck-boost operation. It is preferable.

DESCRIPTION OF SYMBOLS 1 Lighting system 2 Lighting apparatus 4 LED light source 6 DC power supply 8 Lighting fixture 10 Buck converter circuit 14 Constant current control circuit C1 Input side capacitor C2 Output smoothing capacitor C4 Capacitor CN1 Input terminal block CN2 Output terminal block D1 Backflow prevention diode D2 Diode 12 Control IC
L1 Coil L2 Secondary winding OP1 Comparators R1 to R3 Resistor Vcc Control power supply Vref Constant voltage source

Claims (5)

An input terminal portion having a positive input terminal and a negative input terminal;
A diode having an anode connected to the positive input terminal;
An input-side capacitor that is charged by applying a voltage of the cathode of the diode to one end;
A power conversion circuit that receives DC power from a connection point between the cathode of the diode and the one end of the input-side capacitor, and converts the DC power;
A light emitting element that is lit by the power output by the power conversion circuit;
With
The lighting fixture with which the said input terminal part and the said power converter circuit were connected, without pinching | interposing another power converter circuit in between. The power conversion circuit includes an output smoothing capacitor,
The lighting fixture according to claim 1, wherein a capacity of the input side capacitor is larger than a capacity of the output smoothing capacitor. DC power supply,
An input terminal portion having a positive input terminal and a negative input terminal, connected to the DC power supply;
A diode having an anode connected to the positive input terminal;
An input-side capacitor that is charged by applying a voltage of the cathode of the diode to one end;
A power conversion circuit that receives DC power from a connection point between the cathode of the diode and the one end of the input-side capacitor, and converts the DC power;
A light emitting element that is lit by the power output by the power conversion circuit;
With
The lighting system in which the input terminal unit and the power conversion circuit are connected without interposing another power conversion circuit therebetween.   The lighting system according to claim 3, wherein the DC power source is at least one of a photovoltaic power generation system and a storage battery. The power conversion circuit includes an output smoothing capacitor,
The illumination system according to claim 3 or 4, wherein a capacitance of the input-side capacitor is larger than a capacitance of the output smoothing capacitor.

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