JP2018143095A - Lighting device and lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of suppressing overshoot in startup, and a lighting fixture.SOLUTION: A control circuit section 40a executes control for fixing an ON time length ton and a term T of a control signal in startup for raising voltage in both terminals of a smoothing capacitor 17. Such control is implemented during a term T1. When the voltage in both the terminals of the smoothing capacitor 17 becomes equal to or higher than a target value VPFC, the control circuit section 40a then switches to feedback control and implements known power factor improvement control. The feedback control is being implemented during a term T2. During the feedback control, at least one of the ON time length ton and the term T of the control signal is variable and a voltage value detected by potential dividing circuits of resistors 15 and 16 is fed back to a control signal of a switching element 11 in such a manner that the voltage in both the terminals of the smoothing capacitor 17 is matched with the target value VPFC.SELECTED DRAWING: Figure 2

Description

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

  Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 2009-189158, an illumination power supply device that performs feedback control so as to charge an output smoothing capacitor at startup is known. In the power supply device according to this prior art, the first voltage is first targeted at the start-up (including not only the start-up after a long-time stop but also the restart) charging the smoothing capacitor connected to the power factor correction circuit. The smoothing capacitor output voltage is turned on so that the smoothing capacitor is charged by feedback control with a value and then the smoothing capacitor is charged by feedback control with a second voltage, which is a larger regular target voltage, as a target value. Feedback to the duty ratio. By setting the target value in two steps, the overshoot of the output voltage is suppressed to be small.

JP 2009-189158 A

  However, since the above-described conventional technique eventually performs feedback control even during charging at the second target value, there is a problem in that there is a limit to minimizing overshoot.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lighting device and a lighting fixture that can suppress an overshoot of an output voltage when a smoothing capacitor is charged. .

  The lighting device according to the present invention includes a switching element, a smoothing capacitor that is charged by switching the switching element, output voltage detecting means that detects a voltage across the smoothing capacitor, and a control terminal of the switching element. A control circuit for supplying a control signal to the control signal, and the control circuit executes control for fixing an ON time width and a period of the control signal when the voltage detected by the output voltage detecting means is less than a threshold value. When the voltage detected by the output voltage detection means becomes equal to or higher than the threshold, the control signal is switched to feedback control in which at least one of the ON time width and the period of the control signal is variable and the threshold is set as a target value.

  A lighting fixture according to the present invention includes a light emitting element and a lighting device that lights the light emitting element, and the lighting device includes a switching element and a smoothing capacitor that is charged by switching the switching element, An output voltage detecting means for detecting a voltage across the smoothing capacitor; and a control circuit for supplying a control signal to a control terminal of the switching element, wherein the control circuit is configured to charge the smoothing capacitor when the output is started. When the voltage detected by the voltage detection means is less than a threshold value, control is performed to fix the on-time width and period of the control signal, and when the voltage detected by the output voltage detection means exceeds the threshold value, the control signal Is switched to feedback control in which at least one of the ON time width and the period is variable and the threshold is set as a target value.

  According to the present invention, when the voltage is less than the threshold, the on-time width and period of the control signal are fixed, and when the voltage exceeds the threshold, the control is switched to feedback control. Can be suppressed.

It is a circuit diagram which shows the lighting device and lighting fixture concerning embodiment of this invention. It is a time chart which shows operation | movement of the lighting device concerning embodiment of this invention. It is a figure which shows the control signal waveform of the lighting device concerning embodiment of this invention.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a lighting device 1 and a lighting fixture 100 according to an embodiment of the present invention. The lighting fixture 100 includes a lighting device 1 and an LED module 27 that is turned on by the lighting device 1. The lighting device 1 is connected to a positive input terminal and a negative input terminal via a switch (not shown). The lighting device 1 includes a power factor correction circuit 2 that is a step-up chopper circuit and a buck converter circuit 3. The positive input terminal and the negative input terminal of the lighting device 1 are connected to the AC power source 7, and the AC voltage is rectified by the rectifier circuit 8 to become a DC voltage, and the LED module 27 using the power factor correction circuit 2 and the back converter circuit 3. A direct current to be supplied to is generated. The LED module 27 includes a plurality of LED elements 26. In addition, it may replace with an LED element and may provide the organic EL module which provided the organic EL element.

  The power factor correction circuit 2 includes a rectifier circuit 8 that is a diode bridge, a capacitor 9, an inductor (coil) 10, a switching element 11 that is a MOSFET, a diode 14, and a smoothing capacitor 17. The capacitor 9 has one end connected to the high potential side of the rectifier circuit 8 and the other end connected to the low potential side of the rectifier circuit 8. One end of the inductor (coil) 10 is connected to the high potential side of the rectifier circuit 8. The switching element 11 is connected to the other end of the inductor 10. The diode 14 has an anode terminal connected to a connection point between the switching element 11 and the inductor 10. The smoothing capacitor 17 has a positive electrode connected to the cathode terminal of the diode 14 and a negative electrode connected to the low potential side of the rectifier circuit 8.

  The power factor correction circuit 2 includes a series circuit of a resistor 15 and a resistor 16 connected in parallel to the smoothing capacitor 17. The voltage across the smoothing capacitor 17 is divided by resistors 15 and 16 and input to the control circuit 40. A series circuit of resistors 31 and 32 that divide the voltage across the capacitor 9 is also provided, and the divided voltage is input to the control circuit 40. The control circuit unit 40a of the control circuit 40 supplies a control signal for turning on and off the switching element 11 to the gate of the switching element 11 as a drive signal based on these input values.

  The buck converter circuit 3 includes a series circuit of a switching element 18 made of a MOSFET and a diode 21, and this series circuit is connected in parallel with the smoothing capacitor 17 of the power factor correction circuit 2. The buck converter circuit 3 includes a series circuit of a choke coil 22, a smoothing capacitor 23, and a resistor 24, and this series circuit is connected in parallel to the diode 21. The resistor 24 is for detecting the LED current flowing through the LED module 27. The buck converter circuit 3 is a so-called non-insulated step-down converter. The detection voltage from the resistor 24 that detects the LED current is input to the control circuit 40, and the control circuit unit 40b of the control circuit 40 is configured to convert the current flowing through the LED element to a constant current based on the detection voltage. 3 switching element 18 is turned on and off.

FIG. 2 is a time chart showing the operation of the lighting device 1. FIG. 3 is a diagram illustrating control signal waveforms of the lighting device 1, in which a fixed on-time width ton and a fixed period T of a control signal for driving the switching element 11 are schematically illustrated. When the voltage detected by the voltage dividing circuit of the resistors 15 and 16 is less than the target value V _PFC at the time of starting up the voltage across the smoothing capacitor 17, the control circuit unit 40a controls the on-time width ton and period T of the control signal. To fix. Such control is performed during the period T1 in FIG. After that, when the voltage across the smoothing capacitor 17 becomes equal to or higher than the target value V _PFC , the control circuit unit 40a switches to feedback control and implements known power factor correction control (PFC control), preferably critical mode PFC control. The period T2 in FIG. 2 is during feedback control. Thus, the target value V _PFC is a threshold value for switching the control content to feedback control. Feedback control is at least one of a variable on-time width ton and the period T of the control signal, the voltage value detected by the voltage divider resistors 15 and 16 to match the voltage across the smoothing capacitor 17 to the target value V _PFC Is fed back to the control signal. For the feedback control to be performed by the power factor correction circuit, various known techniques may be adopted as necessary.

The DC voltage output from the rectifier circuit 8, that is, the input voltage to the power factor correction circuit 2, increases as the AC voltage effective value (or amplitude) of the AC power supply 7 increases, and the switching element 11 is turned on as the input voltage increases. The voltage waveform rises suddenly. Therefore, when it is less than the period T1, that is, the target value V _PFC , the control circuit 40 variably sets the fixed value of the on-time width ton according to the magnitude of the voltage detected by the voltage dividing circuit of the resistors 31 and 32. Is preferred. Specifically, as shown in FIGS. 3A and 3B, it is preferable to set the on-time width ton to a longer value as the voltage detected by the voltage dividing circuit of the resistors 31 and 32 is smaller. For example, the AC power supply 7 is the ON time width _{ton 100} when it is AC100V, AC power supply 7 is greater than the on time width _{ton 200} when it is AC200V _{(i.e., ton 100>} ton _200). On time width _{ton 200} when the AC power supply 7 is AC200V, the AC power source 7 is equal to or larger than the ON time width _{ton 242} when it is AC242V _{(i.e., ton 200} ≧ _{ton 242).} A control signal in which the ON time width is fixed with a different value for each input voltage is supplied to the switching element 11 during the period T1.

If the on-time width ton fixed in the period T1 in FIG. 2 is too short, it takes a long time to reach the target voltage _VPFC due to the charge consumption of the smoothing capacitor 17 due to the load, that is, the power consumption of the LED module 27. It will take. Therefore, the fixed value of the on-time width ton is preferably set to an on-time width in which the smoothing capacitor 17 is charged with a charge amount exceeding the charge consumption amount of the smoothing capacitor 17 due to the load, that is, the power consumption of the LED module 27.

DESCRIPTION OF SYMBOLS 1 Lighting device, 2 Power factor improvement circuit, 3 Buck converter circuit, 7 AC power supply, 8 Rectifier circuit, 9 Capacitor, 10 Inductor, 11 Switching element, 14 Diode, 15 Resistance, 16 Resistance, 17 Smoothing capacitor, 18 Switching element, 21 diodes, 22 choke coils, 23 smoothing capacitors, 24 resistors, 26 elements, 27 modules, 31, 32 resistors, 40 control circuits, 40a control circuit units, 40b control circuit units, 100 lighting fixtures

Claims (5)

A switching element;
A smoothing capacitor that is charged by switching the switching element;
Output voltage detection means for detecting the voltage across the smoothing capacitor;
A control circuit for supplying a control signal to a control terminal of the switching element;
With
When the voltage detected by the output voltage detection means is less than a threshold value, the control circuit executes control to fix the ON time width and period of the control signal, and the voltage detected by the output voltage detection means is the threshold value. When it becomes above, at least one of the ON time width and period of the control signal is variable, and the lighting device is switched to feedback control using the threshold value as a target value. Provided with an input voltage detection means for detecting the magnitude of the input voltage to the lighting device,
The control circuit variably sets the fixed value of the on-time width according to the magnitude of the voltage detected by the input voltage detecting means when the voltage detected by the output voltage detecting means is less than the threshold value. The lighting device according to claim 1.   The lighting device according to claim 2, wherein the fixed value of the on-time width is set to an on-time width in which the smoothing capacitor is charged with a charge amount that exceeds a charge consumption amount of the smoothing capacitor due to power consumption of a load.   The lighting device according to any one of claims 1 to 3, wherein the control circuit fixes the on-time width and the period at start-up to raise a voltage across the smoothing capacitor. A light emitting element;
A lighting device for lighting the light emitting element;
With
The lighting device is
A switching element;
A smoothing capacitor that is charged by switching the switching element;
Output voltage detection means for detecting the voltage across the smoothing capacitor;
A control circuit for supplying a control signal to a control terminal of the switching element;
With
The control circuit executes control for fixing an on-time width and a period of the control signal when the voltage detected by the output voltage detection means at start-up for charging the smoothing capacitor is less than a threshold, and the output voltage detection When the voltage detected by the means becomes equal to or higher than the threshold value, the lighting apparatus is switched to feedback control in which at least one of the ON time width and the period of the control signal is variable and the threshold value is a target value.

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