WO2018123056A1 - Lighting device and illumination apparatus - Google Patents

Lighting device and illumination apparatus Download PDF

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Publication number
WO2018123056A1
WO2018123056A1 PCT/JP2016/089196 JP2016089196W WO2018123056A1 WO 2018123056 A1 WO2018123056 A1 WO 2018123056A1 JP 2016089196 W JP2016089196 W JP 2016089196W WO 2018123056 A1 WO2018123056 A1 WO 2018123056A1
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WO
WIPO (PCT)
Prior art keywords
delay time
control unit
mosfet
output
lighting device
Prior art date
Application number
PCT/JP2016/089196
Other languages
French (fr)
Japanese (ja)
Inventor
岳秋 飯田
雄一郎 伊藤
Original Assignee
三菱電機株式会社
三菱電機照明株式会社
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 三菱電機株式会社, 三菱電機照明株式会社 filed Critical 三菱電機株式会社
Priority to PCT/JP2016/089196 priority Critical patent/WO2018123056A1/en
Priority to JP2018558794A priority patent/JP6694078B2/en
Priority to PCT/JP2017/025307 priority patent/WO2018123115A1/en
Publication of WO2018123056A1 publication Critical patent/WO2018123056A1/en
Priority to JP2020073450A priority patent/JP2020109775A/en

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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10Controlling the light source
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/10Controlling the light source
    • H05B47/17Operational modes, e.g. switching from manual to automatic mode or prohibiting specific operations

Definitions

  • the present invention relates to a lighting device and a lighting fixture for lighting a light source.
  • the lighting device has a PFC (Power Factor Correction) circuit that is a power factor correction circuit for suppressing harmonics of the input current and improving the power factor.
  • PFC Power Factor Correction
  • Patent Document 1 discloses a method of suppressing an increase in switching frequency at light load and suppressing decrease in on-time by switching the operation mode of the PFC circuit to current discontinuous mode control at light load. Yes.
  • Patent Document 1 has a high harmonic suppression effect because the PFC circuit operates by current critical mode control at high output.
  • the current critical mode control has a problem that the switching loss is large because the switching frequency is higher than that in the case of performing the current discontinuous mode control.
  • the present invention has been made in view of the above, and an object thereof is to obtain a lighting device capable of reducing switching loss while suppressing harmonics of input current.
  • the lighting device improves the power factor by suppressing the harmonics of the rectifier circuit that rectifies AC power and is output from the rectifier circuit.
  • a DC conversion circuit that converts DC power into DC power and supplies the light source to the light source, and a control unit that controls the DC conversion circuit.
  • the DC conversion circuit is disposed between the smoothing capacitor and the smoothing capacitor and rectifier circuit.
  • the control unit includes a switching element and a coil through which a current output from the rectifier circuit flows, and the control unit switches the switching element from the time when the current flowing through the coil becomes zero until a delay time set in the control unit elapses. The switching element is turned on when the delay time elapses after being turned off.
  • the lighting device according to the present invention has an effect of reducing switching loss while suppressing harmonics of the input current.
  • FIG. 1 shows the structure of the electric current control part shown in FIG. Timing chart showing the relationship between the current flowing through the light source, the current flowing through the coil, and the control signal of the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 1 is a timing chart showing the relationship between the current flowing through the coil constituting the PFC circuit shown in FIG. 1, the drain voltage of the MOSFET, and the gate voltage of the MOSFET.
  • MOSFET Metal Oxide Semiconductor Field Effect Transistor
  • Diagram showing the waveform when dimming with current critical mode control without delay time Diagram showing waveform when dimming with delay time
  • FIG. 1 is a configuration diagram of a lighting device and a lighting fixture according to the first embodiment.
  • the luminaire 200 is connected to the AC power source 1 and converts the power supplied from the AC power source 1 through the input filter 2 that smoothes the AC current output from the AC power source 1 into a DC current that can be input to the light source 8.
  • the lighting device 100 that outputs the light
  • the light source 8 that is turned on by the power supplied from the lighting device 100
  • the dimmer 10 that outputs a dimming signal for turning on, turning off, or dimming the light source 8.
  • the light source 8 is composed of an LED group in which a plurality of LEDs are directly connected. One end of the LED group is connected to the positive side DC bus P, and the other end of the LED group is connected to the negative side DC bus N.
  • the lighting device 100 includes an input filter 2, a rectifier circuit 3 connected to the input filter 2, a capacitor 4 connected in parallel to the rectifier circuit 3, a DC conversion circuit 30, and a current detection that detects a current flowing through the light source 8. And a control unit 9 for controlling the PFC circuit 5 and the current control unit 7.
  • the DC conversion circuit 30 has a function of improving the power factor by suppressing harmonics of the current input from the AC power supply 1 and converting the power output from the rectifier circuit 3 into DC power and supplying it to the light source 8.
  • the DC conversion circuit 30 includes a PFC circuit 5 for improving the power factor by suppressing harmonics of the current input from the AC power supply 1, a smoothing capacitor 6 for smoothing the output voltage of the PFC circuit 5, and a light source 8. And a current control unit 7 for controlling the magnitude of the output current.
  • the input filter 2 disposed between the AC power supply 1 and the rectifier circuit 3 includes a coil 21 and a capacitor 22 and reduces high-frequency noise superimposed on the current output from the AC power supply 1.
  • the coil 21 is connected in series to the AC power source 1.
  • One end of the coil 21 is connected to one end of the AC power supply 1, and the other end of the coil 21 is connected to the capacitor 22 and the rectifier circuit 3.
  • the other end of the capacitor 22 is connected to the AC power source 1 and the rectifier circuit 3.
  • the rectifier circuit 3 is disposed between the input filter 2 and the PFC circuit 5 and converts AC power supplied from the AC power source 1 into DC power.
  • the rectifier circuit 3 is composed of a diode bridge in which four diodes are combined.
  • the configuration of the rectifier circuit 3 is not limited to this, and may be configured by combining MOSFETs that are unidirectional conducting elements.
  • the capacitor 4 is connected in parallel to the output of the rectifier circuit 3, and smoothes the output voltage of the rectifier circuit 3.
  • One end of the capacitor 4 is connected to the positive side DC bus P, and the other end of the capacitor 4 is connected to the negative side DC bus N.
  • the PFC circuit 5 is disposed between the rectifier circuit 3 and the current control unit 7.
  • the PFC circuit 5 includes a MOSFET 51 that is a switching element, a coil 52, and a diode 53.
  • the PFC circuit 5 boosts the output voltage of the rectifier circuit 3 by turning on and off the MOSFET 51 by the control unit 9, and outputs the boosted voltage to the smoothing capacitor 6. Further, the PFC circuit 5 has a function of suppressing the harmonics of the input current and improving the power factor by the control described later.
  • the PFC circuit 5 is configured by a boost chopper circuit will be described.
  • the PFC circuit 5 may be configured by a circuit such as a step-up / step-down chopper circuit, a flyback circuit, a flyforward circuit, a SEPIC (Single Ended Primary Inverter Converter), a Zeta converter, or a Cuk converter.
  • a circuit such as a step-up / step-down chopper circuit, a flyback circuit, a flyforward circuit, a SEPIC (Single Ended Primary Inverter Converter), a Zeta converter, or a Cuk converter.
  • the coil 52 is disposed between the capacitor 4 and the MOSFET 51 on the positive side DC bus P.
  • a primary winding 52 a and a secondary winding 52 b are formed in the coil 52 by winding an insulating wire around a core (not shown).
  • One end of the primary winding 52 a is connected to one end of the capacitor 4.
  • the other end of the primary winding 52 a is connected to the anode of the diode 53.
  • One end of the secondary winding 52b is connected to the control unit 9, and the other end of the secondary winding 52b is connected to the negative-side DC bus N.
  • a voltage having a different polarity is applied to the primary winding 52a as the MOSFET 51 is turned on / off.
  • the voltage generated in the secondary winding 52b is equal to the voltage corresponding to the applied voltage of the primary winding 52a and the turns ratio n.
  • the drain of the MOSFET 51 is connected to the primary winding 52 a and the anode of the diode 53 in the positive side DC bus P.
  • the source of the MOSFET 51 is connected to the other end of the capacitor 4, the other end of the secondary winding 52 b, and the other end of the smoothing capacitor 6 on the negative DC bus N.
  • the gate of the MOSFET 51 is connected to the control unit 9. A control signal output from the control unit 9 is input to the gate of the MOSFET 51. On / off control of the MOSFET 51 is performed by inputting the control signal.
  • the diode 53 is disposed between the MOSFET 51 and the smoothing capacitor 6 in the positive side DC bus P.
  • the anode of the diode 53 is connected to the coil 52 and the MOSFET 51, and the cathode of the diode 53 is connected to the smoothing capacitor 6.
  • the smoothing capacitor 6 is disposed between the PFC circuit 5 and the current control unit 7. One end of the smoothing capacitor 6 is connected to the positive side DC bus P, and the other end of the smoothing capacitor 6 is connected to the negative side DC bus N.
  • the current detector 11 detects a current flowing through the light source 8 and outputs current information corresponding to the detected current value to the controller 9.
  • a configuration in which a current is detected using a shunt resistor or a hall sensor can be exemplified.
  • the control unit 9 includes a target value output unit 91, a zero current detection unit 92, a switching control unit 93, a current input unit 94, and a voltage detection unit 95.
  • the target value output unit 91 is connected to the dimmer 10, and the target value output unit 91 determines an output current target value corresponding to the type of the dimming signal output from the dimmer 10, and the determined output current The target value is output to the switching control unit 93.
  • the output current target value is a signal that specifies a current target value that the lighting device 100 outputs to the light source 8.
  • the voltage detector 95 detects the voltage of the smoothing capacitor 6 and outputs voltage information corresponding to the detected voltage value to the switching controller 93.
  • An example of the voltage detector 95 is a voltage dividing circuit. In the voltage dividing circuit, one end of a series resistor in which two resistors are connected in series is connected to the positive side DC bus P, and the other end of the series resistor is connected to the negative side DC bus N. This circuit divides the voltage applied to the smoothing capacitor 6.
  • the switching control unit 93 outputs a control signal for controlling the current control unit 7 based on the output current target value output from the target value output unit 91 and the current information input to the current input unit 94.
  • the switching control unit 93 stores the output voltage target value of the PFC circuit 5 in advance, and based on at least the voltage information output from the voltage detection unit 95 and the stored output voltage target value. A control signal for controlling the signal is output.
  • the current control unit 7 converts the DC voltage output from the PFC circuit 5 into a DC current that can be input to the light source 8 based on the control signal output from the switching control unit 93.
  • FIG. 2 is a diagram showing a configuration of the current control unit shown in FIG.
  • the current control unit 7 shown in FIG. 2 includes a step-down chopper circuit.
  • a circuit such as a step-up / step-down chopper circuit, a flyback circuit, a fly-forward circuit, a SEPIC, a Zeta converter, or a Cuk converter is used. It may be composed of
  • the current control unit 7 includes a MOSFET 71, a coil 72, a diode 73, and a capacitor 74.
  • MOSFET 71 is arranged on positive side DC bus P.
  • the drain of the MOSFET 71 is connected to one end of the smoothing capacitor 6 and the cathode of the diode 53 shown in FIG.
  • the source of the MOSFET 71 is connected to the cathode of the diode 73 and one end of the coil 72.
  • the gate of the MOSFET 71 is connected to the switching control unit 93.
  • a control signal output from the switching control unit 93 is input to the gate of the MOSFET 71.
  • the control signal is a signal for controlling on / off of the MOSFET 71.
  • One end of the coil 72 is connected to the source of the MOSFET 71 and the cathode of the diode 73.
  • the other end of the coil 72 is connected to one end of the capacitor 74 and one end of the light source 8 shown in FIG.
  • the cathode of the diode 73 is connected to the source of the MOSFET 71 and one end of the coil 72.
  • the anode of the diode 73 is connected to the other end of the smoothing capacitor 6 shown in FIG. 1, the other end of the capacitor 74, and the other end of the light source 8 shown in FIG.
  • FIG. 3 is a timing chart showing the relationship between the current flowing through the light source, the current flowing through the coil, and the control signal of the MOSFET.
  • FIG. 3 shows the current flowing through the light source 8, the current flowing through the coil 72, and the control signal of the MOSFET 71 in order from the top.
  • the horizontal axis represents time.
  • the switching cycle Tsw is equal to the time from when the control signal of the MOSFET 71 changes from OFF to ON until the control signal of the MOSFET 71 changes from OFF to ON again.
  • the switching period Tsw is set in the switching control unit 93 in advance.
  • the on time Ton is equal to the time from when the control signal of the MOSFET 71 changes from off to on until it changes from on to off.
  • the current flowing through the coil 72 has a triangular waveform, but the current output to the light source 8 is smoothed by the capacitor 74, and the average value of the current flowing through the coil 72 is output from the current control unit 7.
  • the switching control unit 93 makes the switching period Tsw for turning on the MOSFET 71 constant, and changes the on-time Ton according to the target value of the output current.
  • the control method for obtaining a specific output by adjusting the on-time Ton in this way is called duty control because the ratio of the on-time Ton to the switching period Tsw is called duty.
  • FIG. 4 is a timing chart showing the relationship between the current flowing through the coil constituting the PFC circuit shown in FIG. 1, the drain voltage of the MOSFET, and the gate voltage of the MOSFET.
  • FIG. 4 shows, in order from the top, the current of the AC power source 1 input to the lighting device 100, the current flowing through the coil 52, the drain voltage of the MOSFET 51, and the gate voltage of the MOSFET 51.
  • the horizontal axis represents time.
  • the current of the AC power supply 1 input to the lighting device 100 is indicated as “input current”.
  • the cycle in which the gate voltage of the MOSFET 51 is turned on and off is shown longer than the actual period.
  • the period when the gate voltage of the MOSFET 51 is turned on and off is equal to the time from when the gate voltage of the MOSFET 51 changes from off to on until when the gate voltage of the MOSFET 51 changes from off to on again.
  • the MOSFET 51 When the ON time set in the switching control unit 93 has elapsed, the MOSFET 51 is turned off, thereby forming a closed circuit of the coil 52, the diode 53, and the smoothing capacitor 6. In this closed circuit, the energy accumulated in the coil 52 is released, and the smoothing capacitor 6 is charged.
  • the OFF state of the MOSFET 51 is maintained from when the current flowing through the coil 52 becomes zero until the delay time Tdelay elapses, and when the delay time Tdelay elapses, the MOSFET 51 is turned on again. That is, the control signal of the MOSFET 51 remains off until the delay time Tdelay elapses from the time when the current flowing through the coil 52 becomes zero, and the control signal of the MOSFET 51 is turned on when the delay time Tdelay elapses. Change.
  • the current flowing through the coil 52 has a triangular waveform, and the apex thereof becomes a sine wave envelope as indicated by a dotted line.
  • the current input from the AC power source 1 is smoothed by the input filter 2, and the average value of the coil current flowing through the coil 21 is input to form a sine wave current waveform.
  • the control unit 9 detects the voltage applied to the smoothing capacitor 6 and performs feedback control so that the detected voltage follows the target value, whereby the on-time of the MOSFET 51 is controlled.
  • the response time of the feedback control is set so that the loop gain of the feedback control becomes 1 time (0 dB) or less after being 1/2 of 1 cycle of the AC power supply 1. In other words, the response time of the feedback control is set to be 1 (0 dB) or less at a frequency that is 2 times or less of the frequency of the AC power supply 1.
  • the feedback control loop gain is set to 1 (0 dB) or less at a frequency of 100 Hz or less of a half cycle (half wave) of the power supply frequency, that is, a cycle of 10 msec or more.
  • the feedback control is set so as not to respond in a cycle shorter than 1 ⁇ 2 of the power cycle.
  • the same effect can be obtained by setting the on-time update cycle to a cycle corresponding to half the cycle of the AC power supply 1 or a cycle longer than the cycle corresponding to half the cycle of the AC power supply 1.
  • the MOSFET 51 is switching-controlled by current critical mode control without providing the delay time Tdelay. Therefore, the average value of the current flowing through the coil 52 becomes a complete sine wave, and high power A rate improvement effect can be expected.
  • the lighting device 100 provides the delay time Tdelay and performs switching control of the MOSFET 51 by current discontinuous mode control, thereby lowering the switching frequency compared to the case of current critical mode control. Therefore, the switching loss generated in the MOSFET 51 can be reduced.
  • the delay time Tdelay is set within a range in which an increase in harmonics can be allowed.
  • An example of a range in which an increase in harmonics is allowable is within a current harmonic limit value defined by Japanese Industrial Standards.
  • the control unit 9 turns on the MOSFET 51 near the bottom of the voltage oscillation of the MOSFET 51 so that the drain voltage has a steep drain voltage. It is possible to suppress fluctuations and suppress noise caused by switching.
  • the control unit 9 turns on the MOSFET 51 at least at the second and subsequent bottoms of the bottom of the voltage oscillation of the MOSFET 51, so that a delay time can be provided with certainty.
  • the switching control unit 93 performs control so as to shorten the ON time of the MOSFET 51 in order to reduce the input current of the AC power supply 1.
  • FIG. 5 is a diagram showing a waveform when dimming with current critical mode control without providing a delay time
  • FIG. 6 is a diagram showing a waveform when dimming with a delay time. 5 and 6 are for explaining an outline of the switching operation of the PFC circuit 5 when the light source 8 is dimmed.
  • FIGS. 5 and 6 shows the input current of the AC power supply 1, the current flowing through the coil 52, the drain voltage of the MOSFET 51, and the gate voltage of the MOSFET 51, as in FIG. 4.
  • the horizontal axis represents time.
  • FIG. 7 is a graph showing the on-time and switching frequency characteristics of the MOSFET, which change according to the dimming rate.
  • FIG. 7 shows, in order from the top, the delay time Tdelay, the ON time of the MOSFET 51, the switching frequency of the control signal for controlling the MOSFET 51, and the dimming rate of the light source 8.
  • the dotted line represents the delay time Tdelay, the ON time of the MOSFET 51, and the switching frequency when the dimming rate is changed when the current critical mode control is performed.
  • a solid line represents the delay time Tdelay, the ON time of the MOSFET 51, and the switching frequency when the dimming rate is changed when the current discontinuous mode control in which the delay time is set is performed.
  • the delay time Tdelay By providing the delay time Tdelay and performing the current discontinuous mode control, an increase in switching frequency during dimming can be suppressed and switching loss can be reduced as compared with current critical mode control. Further, the ON time of the MOSFET 51 can be lengthened, and the MOSFET 51 can be controlled on and off more reliably.
  • FIG. 8 is a first diagram showing the MOSFET on-time and switching frequency when the delay time is changed in accordance with the dimming rate.
  • a threshold value is provided for the dimming rate, and when the dimming rate exceeds the threshold value, the control unit 9 sets the delay time as the first delay time Tdelay 1st, and the dimming rate is the threshold value.
  • the delay time is the second delay time Tdelay2nd.
  • the second delay time Tdelay2nd is longer than the first delay time Tdelay1st, and is longer as the dimming rate decreases.
  • the threshold, the first delay time Tdelay1st, and the second delay time Tdelay2nd shown in FIG. 8 are set in the control unit 9 in advance.
  • the first delay time Tdelay1st is set when a dimming rate exceeding the threshold is input
  • the second delay time Tdelay2nd is set when a dimming rate less than the threshold is input.
  • the control unit 9 stores the minimum on-time Ton_min.
  • the dimming control can be performed so that the on-time of the MOSFET 51 is not shorter than the minimum on-time Ton_min.
  • FIG. 9 is a second diagram showing the MOSFET on-time and switching frequency when the delay time is changed in accordance with the dimming rate.
  • a plurality of threshold values 1, 2, and 3 are set for the dimming rate.
  • the plurality of thresholds 1, 2, and 3 are higher in the order of threshold 3, threshold 2, and threshold 1.
  • a plurality of delay times Tdelay 1, 2, 3, 4 corresponding to a plurality of threshold values 1, 2, 3 are set. It is assumed that a plurality of threshold values 1, 2, 3 and a plurality of delay times Tdelay 1, 2, 3, 4 are set in the control unit 9.
  • Delay time Tdelay4 is set when a dimming rate of threshold 3 or less is input.
  • the delay time Tdelay3 is set when a dimming rate that exceeds the threshold 3 and is equal to or less than the threshold 2 is input.
  • the delay time Tdelay2 is set when a dimming rate that exceeds the threshold 2 and is equal to or less than the threshold 1 is input.
  • the delay time Tdelay1 is set when a dimming rate exceeding the threshold value 1 is input.
  • the control unit 9 provides a plurality of threshold values for the dimming rate, and controls the switching elements using a plurality of delay times having different lengths according to a range between adjacent threshold values. Specifically, when the delay time Tdelay1 is provided and the light is dimmed in the direction in which the current of the light source 8 decreases and the dimming rate reaches the threshold value 1, the on-time of the MOSFET 51 is the minimum on-time. When the time is shortened to the time Ton_min, the control unit 9 increases the delay time from Tdelay1 to Tdelay2. This can prevent the on time of the MOSFET 51 from becoming shorter than the minimum on time Ton_min.
  • FIG. 10 is a diagram showing changes over time in delay time, MOSFET on-time, and light source dimming rate when the delay time is extended from Tdelay1 to Tdelay2 with threshold value 1 of dimming rate shown in FIG. is there.
  • the delay time Tdelay When the delay time Tdelay is abruptly extended, the switching frequency of the MOSFET 51 suddenly changes, the output of the PFC circuit 5 fluctuates, and the voltage of the smoothing capacitor 6 fluctuates, so that the output current of the current control unit 7 connected to the subsequent stage is constant. Therefore, the light source 8 cannot be lit stably. Therefore, when the delay time Tdelay is extended, the change amount maximum value Tstep of the delay time Tdelay is provided, and the maintenance time Tk that maintains the delay time Tdelay without change is provided, thereby delaying the time change of the delay time Tdelay. be able to. By performing this control, a sudden change in the switching frequency of the MOSFET 51 can be suppressed.
  • the maintenance time Tk for maintaining the delay time Tdelay is set longer than the response time for feedback control of the ON time of the MOSFET 51. As a result, a time during which the ON time of the MOSFET 51 is constant is ensured, and the output of the PFC circuit 5 can be stabilized.
  • FIG. 11 is a flowchart for explaining the operation of the control unit when extending the delay time.
  • the controller 9 When the light source 8 is turned on with the delay time Tdelay1 provided, the controller 9 performs dimming in the direction of decreasing the current of the light source 8 (S11), and when the dimming rate is greater than the threshold 1 (S12, No ), The delay time is not changed (S15). When the dimming rate is equal to or less than the threshold value 1 (S12, Yes), the control unit 9 does not change the delay time unless the delay time maintenance time Tk has elapsed after the final change of the delay time (S13, No). (S15).
  • the control unit 9 does not change the delay time if the delay time is Tdelay2 or more (S14, No) ( S15). If the delay time is smaller than Tdelay2 (S14, Yes), the delay time is extended by Tstep (S16).
  • the control unit 9 changes the delay time from Tdelay2 to Tdelay1. To shorten.
  • FIG. 12 is a diagram showing temporal changes in delay time, MOSFET on-time, and light source dimming rate when the delay time is shortened from Tdelay2 to Tdelay1 with the threshold value 1 of dimming rate shown in FIG. is there.
  • the delay time is sharply shortened, the switching frequency of the MOSFET 51 suddenly changes, the output of the PFC circuit 5 fluctuates, and the voltage of the smoothing capacitor 6 fluctuates, so that the output current of the current control unit 7 connected to the subsequent stage is constant Therefore, the light source 8 cannot be lit stably.
  • the delay time Tdelay is shortened, the change amount maximum value Tstep of the delay time Tdelay is provided, and the maintenance time Tk that maintains the delay time Tdelay without change is provided, thereby delaying the time change of the delay time Tdelay. can do.
  • a sudden change in the switching frequency of the MOSFET 51 can be suppressed.
  • the maintenance time Tk for maintaining the delay time Tdelay is set longer than the response time for feedback control of the ON time of the MOSFET 51. As a result, a time during which the ON time of the MOSFET 51 is constant is ensured, and the output of the PFC circuit 5 can be stabilized.
  • FIG. 13 is a flowchart for explaining the operation of the control unit when the delay time is shortened.
  • the control unit 9 performs dimming in the direction of increasing the current of the light source 8 from the lighting state with the delay time Tdelay2 (S21), and when the dimming rate is equal to or less than the threshold 1 (S22, No), The delay time is not changed (S25). If the dimming rate is larger than the threshold value 1 (S22, Yes), the delay time is not changed (S25) if the delay time maintenance time Tk has not passed after the final change of the delay time (S23, No). When the delay time maintaining time Tk has elapsed after the final change of the delay time (S23, Yes), the control unit 9 does not change the delay time if the delay time is equal to or less than Tdelay1 (S24, No) ( S25). If the delay time is larger than Tdelay1 (S24, Yes), the delay time is shortened by Tstep (S26).
  • the light source 8 was comprised by LED
  • LED Organic EL (Electro Luminescence) may be sufficient.
  • FIG. FIG. 14 is a configuration diagram of a lighting device and a lighting fixture according to the second embodiment.
  • the difference between the lighting fixture 200A according to Embodiment 2 and the lighting fixture 200 according to Embodiment 1 is that the lighting fixture 100A is used instead of the lighting device 100 in the lighting fixture 200A.
  • the difference between the lighting device 100A according to the second embodiment and the lighting device 100 according to the first embodiment is that, in the lighting device 100A, a DC conversion circuit is used instead of the PFC circuit 5, the smoothing capacitor 6, and the current control unit 7. 12, and a control unit 9 ⁇ / b> A is used instead of the control unit 9.
  • the DC conversion circuit 12 is a circuit having the functions of the PFC circuit 5, the smoothing capacitor 6, and the current control unit 7.
  • Embodiment 2 describes an example in which the DC conversion circuit 12 is configured by a flyback circuit.
  • the DC conversion circuit 12 may be configured by a circuit such as a fly forward circuit, a step-down chopper, a step-up chopper, a step-up / step-down chopper circuit, a SEPIC, a Zeta converter, or a Cuk converter.
  • the DC conversion circuit 12 includes a MOSFET 121, a transformer 122, a diode 123, a smoothing capacitor 124, a snubber capacitor 125, a snubber resistor 126, and a snubber diode 127.
  • the MOSFET 121 is disposed between the capacitor 4 and the primary side of the transformer 122 in the negative-side DC bus N.
  • the source of the MOSFET 121 is connected to one end of the capacitor 4 and the rectifier circuit 3.
  • the drain of MOSFET 121 is connected to the anode of snubber diode 127 and transformer 122.
  • Snubber capacitor 125, snubber resistor 126 and snubber diode 127 are arranged between capacitor 4 and the primary side of transformer 122.
  • One end of the snubber resistor 126 is connected to the other end of the capacitor 4, the rectifier circuit 3, one end of the snubber capacitor 125, and the transformer 122 via the positive side DC bus P.
  • the other end of the snubber resistor 126 is connected to the other end of the snubber capacitor 125 and one end of the snubber diode 127.
  • the other end of the snubber capacitor 125 is connected to the other end of the snubber resistor 126 and one end of the snubber diode 127.
  • the diode 123 and the smoothing capacitor 124 are disposed between the secondary side of the transformer 122 and the light source 8.
  • the anode of the diode 123 is connected to the transformer 122, and the cathode of the diode 123 is connected to one end of the smoothing capacitor 124 and one end of the light source 8.
  • the other end of the smoothing capacitor 124 is connected to the transformer 122 and the other end of the light source 8.
  • the primary winding 122a, the secondary winding 122b, and the tertiary winding 122c are formed in the transformer 122 by winding an insulating wire around a core (not shown).
  • the direct current conversion circuit 12 converts the output voltage of the rectifier circuit 3 and outputs a direct current to the light source 8 when the MOSFET 121 is on / off controlled.
  • the control unit 9A includes a target value output unit 91, a zero current detection unit 92, a switching control unit 93A, and a current input unit 94.
  • the difference between the control unit 9 shown in FIG. 1 and the control unit 9A shown in FIG. 14 is that, in the control unit 9A, the voltage detection unit 95 is omitted, and the switching control unit 93A is used instead of the switching control unit 93. That is.
  • FIG. 15 is a timing chart showing the relationship between the current flowing through the windings constituting the DC conversion circuit shown in FIG. 14, the drain voltage of the MOSFET, and the gate voltage of the MOSFET.
  • the current of the AC power source 1 input to the lighting device 100A the current flowing through the primary winding 122a, the current flowing through the tertiary winding 122c, the drain voltage of the MOSFET 121, and the MOSFET 121
  • the gate voltage is shown.
  • the horizontal axis represents time.
  • the current of the AC power supply 1 input to the lighting device 100 ⁇ / b> A is indicated as “input current”.
  • the cycle in which the gate voltage of the MOSFET 121 is turned on / off is shown to be longer than the actual period.
  • the period during which the gate voltage of the MOSFET 121 is turned on / off is equal to the time from when the gate voltage of the MOSFET 121 changes from off to on until when the gate voltage of the MOSFET 121 changes from off to on again.
  • the MOSFET 121 When the ON time set in the switching control unit 93A elapses, the MOSFET 121 is turned off to form a closed circuit of the tertiary winding 122c, the diode 123, and the smoothing capacitor 124. In this closed circuit, the energy stored in the primary winding 122a is released, and the smoothing capacitor 124 is charged.
  • the MOSFET 121 is kept off until the delay time Tdelay elapses after the current flowing through the tertiary winding 122c becomes zero, and the MOSFET 121 is turned on again when the delay time Tdelay elapses.
  • the current flowing through the primary winding 122a has a triangular waveform, and a sine wave envelope whose apex is indicated by a dotted line.
  • the current input from the AC power source 1 is smoothed by the input filter 2, and the average value of the coil current flowing through the coil 21 is input to form a sine wave current waveform.
  • the control unit 9A detects the current flowing through the light source 8, and feedback control is performed so that the detected current follows the target value, whereby the on-time of the MOSFET 121 is controlled.
  • the response time of the feedback control is set so that the loop gain of the feedback control is not less than 1/2 of one cycle of the AC power supply 1 and not more than 1 (0 dB). In other words, the response time of the feedback control is set to be 1 (0 dB) or less at a frequency that is 2 times or less of the frequency of the AC power supply 1.
  • the loop gain of the constant current feedback control is set to be 1 (0 dB) or less at a frequency of 100 Hz or less of a half cycle (half wave) of the power supply frequency, that is, a cycle of 10 msec or more.
  • the constant current feedback control is set so as not to respond in a cycle shorter than 1 ⁇ 2 of the power cycle.
  • the fluctuation of the on-time of the MOSFET 121 is suppressed within a half cycle of the power supply cycle, and the envelope of the peak of the current flowing through the primary winding 122a becomes a sine wave waveform.
  • the same effect can be obtained by setting the on-time update cycle to a cycle corresponding to half the cycle of the AC power supply 1 or a cycle longer than the cycle corresponding to half the cycle of the AC power supply 1.
  • the lighting device 100A and the lighting fixture 200A according to the second embodiment are provided with the delay time Tdelay as in the first embodiment, and when the current critical mode control is performed by switching the MOSFET 121 by the current discontinuous mode control. In comparison, since the switching frequency can be lowered, the switching loss generated in the MOSFET 121 can be reduced.
  • the length of the delay time is an output that the DC conversion circuit 30 outputs to the LED instead of the dimming rate.
  • the determination may be made based on the current target value.
  • the magnitude of the output of the DC conversion circuit may be determined by the dimming rate of the LED, may be determined by the output current target value of the LED, or may be determined by the dimming rate of the organic EL. It may be determined.
  • the magnitude of the output of the DC conversion circuit may be determined from the output current target value of the LED.
  • you may comprise the control part which concerns on Embodiment 1, 2 so that the length of delay time may be changed according to an output current target value instead of a light control rate.
  • the configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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Abstract

A lighting device (100) according to the present invention is provided with: a rectification circuit (3) which rectifies AC power; a DC conversion circuit (30) which inhibits higher harmonics of a current and improves the power factor, and converts the power outputted from the rectification circuit (3) into DC power, and supplies the DC power to a light source; and a control unit (9) which controls the DC conversion circuit (30). The DC conversion circuit (30) is provided with: a smoothing capacitor (6); a MOSFET (51) which is disposed between the smoothing capacitor (6) and the rectification circuit (3); and a coil (52) through which the current outputted from the rectification circuit (3) flows. The control unit (9) sets the MOSFET (51) in an off state from the point in time at which the current flowing through the coil (52) becomes zero, until a delay time set in the control unit (9) elapses, and turns on the MOSFET (51) when the delay time has elapsed.

Description

点灯装置及び照明器具Lighting device and lighting apparatus
 本発明は、光源を点灯する点灯装置及び照明器具に関する。 The present invention relates to a lighting device and a lighting fixture for lighting a light source.
 LED(Light Emitting Diode)を光源とした照明器具には、入力電流の高調波に関する規制が定められており、日本国内においては、日本工業規格によって入力電流の高調波に限度値が定められている。そのため、点灯装置は、入力電流の高調波を抑制し、力率を改善するための力率改善回路であるPFC(Power Factor Correction)回路を有する。 For lighting fixtures that use LED (Light Emitting Diode) as a light source, regulations on harmonics of input current are stipulated, and in Japan, limit values are set for harmonics of input current by Japanese Industrial Standards. . Therefore, the lighting device has a PFC (Power Factor Correction) circuit that is a power factor correction circuit for suppressing harmonics of the input current and improving the power factor.
 特許文献1には、軽負荷時においてはPFC回路の動作モードを電流不連続モード制御に切り替えることで、軽負荷時のスイッチング周波数上昇を抑制し、オン時間の減少を抑制する方法が示されている。 Patent Document 1 discloses a method of suppressing an increase in switching frequency at light load and suppressing decrease in on-time by switching the operation mode of the PFC circuit to current discontinuous mode control at light load. Yes.
特許第5152501号公報Japanese Patent No. 5152501
 特許文献1に示される方法では、高出力時において、電流臨界モード制御によりPFC回路が動作するため、高い高調波抑制効果がある。ところが電流臨界モード制御では、電流不連続モード制御を行う場合に比べてスイッチング周波数が高いため、スイッチング損失が大きいという問題がある。 The method disclosed in Patent Document 1 has a high harmonic suppression effect because the PFC circuit operates by current critical mode control at high output. However, the current critical mode control has a problem that the switching loss is large because the switching frequency is higher than that in the case of performing the current discontinuous mode control.
 本発明は、上記に鑑みてなされたものであって、入力電流の高調波を抑制しながらスイッチング損失を低減できる点灯装置を得ることを目的とする。 The present invention has been made in view of the above, and an object thereof is to obtain a lighting device capable of reducing switching loss while suppressing harmonics of input current.
 上述した課題を解決し、目的を達成するために、本発明に係る点灯装置は、交流電力を整流する整流回路と、電流の高調波を抑制して力率を改善すると共に整流回路から出力される電力を直流電力に変換して光源に供給する直流変換回路と、直流変換回路を制御する制御部とを備え、直流変換回路は、平滑コンデンサと、平滑コンデンサ及び整流回路の間に配置されるスイッチング素子と、整流回路から出力される電流が流れるコイルとを有し、制御部は、コイルに流れる電流がゼロになった時点から、制御部に設定された遅延時間が経過するまでスイッチング素子をオフ状態にさせて、遅延時間が経過したときにスイッチング素子をオンさせる。 In order to solve the above-described problems and achieve the object, the lighting device according to the present invention improves the power factor by suppressing the harmonics of the rectifier circuit that rectifies AC power and is output from the rectifier circuit. A DC conversion circuit that converts DC power into DC power and supplies the light source to the light source, and a control unit that controls the DC conversion circuit. The DC conversion circuit is disposed between the smoothing capacitor and the smoothing capacitor and rectifier circuit. The control unit includes a switching element and a coil through which a current output from the rectifier circuit flows, and the control unit switches the switching element from the time when the current flowing through the coil becomes zero until a delay time set in the control unit elapses. The switching element is turned on when the delay time elapses after being turned off.
 本発明に係る点灯装置は、入力電流の高調波を抑制しながらスイッチング損失を低減できるという効果を奏する。 The lighting device according to the present invention has an effect of reducing switching loss while suppressing harmonics of the input current.
実施の形態1に係る点灯装置及び照明器具の構成図Configuration diagram of lighting device and lighting apparatus according to Embodiment 1 図1に示す電流制御部の構成を示す図The figure which shows the structure of the electric current control part shown in FIG. 光源に流れる電流とコイルに流れる電流とMOSFET(Metal Oxide Semiconductor Field Effect Transistor)の制御信号との関係を示すタイミングチャートTiming chart showing the relationship between the current flowing through the light source, the current flowing through the coil, and the control signal of the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 図1に示すPFC回路を構成するコイルに流れる電流とMOSFETのドレイン電圧とMOSFETのゲート電圧との関係を示すタイミングチャート1 is a timing chart showing the relationship between the current flowing through the coil constituting the PFC circuit shown in FIG. 1, the drain voltage of the MOSFET, and the gate voltage of the MOSFET. 遅延時間を設けずに電流臨界モード制御で調光した場合の波形を示す図Diagram showing the waveform when dimming with current critical mode control without delay time 遅延時間を設けて調光した場合の波形を示す図Diagram showing waveform when dimming with delay time 調光率に応じて変化するMOSFETのオン時間及びスイッチング周波数の特性を示す図The figure which shows the characteristic of the ON time and switching frequency of MOSFET which changes according to the light control rate 調光率に応じて遅延時間を変化させた場合のMOSFETのオン時間とスイッチング周波数を示す第1の図1st figure which shows the ON time and switching frequency of MOSFET at the time of changing delay time according to a light control rate 調光率に応じて遅延時間を変化させた場合のMOSFETのオン時間とスイッチング周波数を示す第2の図2nd figure which shows ON time and switching frequency of MOSFET at the time of changing delay time according to a light control rate 図9に示す調光率の閾値1を境にして、遅延時間をTdelay1からTdelay2に延長する場合の、遅延時間、MOSFETのオン時間及び光源の調光率の時間変化を示す図The figure which shows the time change of delay time, MOSFET ON time, and light source dimming rate when delay time is extended from Tdelay1 to Tdelay2 with threshold value 1 of dimming rate shown in FIG. 遅延時間を延長する場合における制御部の動作を説明するためのフローチャートFlowchart for explaining the operation of the control unit when extending the delay time 図9に示す調光率の閾値1を境にして、遅延時間をTdelay2からTdelay1に短縮する場合の、遅延時間、MOSFETのオン時間及び光源の調光率の時間変化を示す図The figure which shows the time change of delay time, MOSFET ON time, and the light control rate of a light source when delay time is shortened from Tdelay2 to Tdelay1 on the threshold value 1 of the light control rate shown in FIG. 遅延時間を短縮する場合における制御部の動作を説明するためのフローチャートFlowchart for explaining the operation of the control unit when the delay time is shortened 実施の形態2に係る点灯装置及び照明器具の構成図Configuration diagram of lighting device and lighting apparatus according to Embodiment 2 図14に示す直流変換回路を構成する巻線に流れる電流とMOSFETのドレイン電圧とMOSFETのゲート電圧との関係を示すタイミングチャート14 is a timing chart showing the relationship between the current flowing through the windings constituting the DC converter circuit shown in FIG. 14, the drain voltage of the MOSFET, and the gate voltage of the MOSFET.
 以下に、本発明の実施の形態に係る点灯装置及び照明器具を図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。 Hereinafter, a lighting device and a lighting fixture according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
実施の形態1.
 図1は実施の形態1に係る点灯装置及び照明器具の構成図である。照明器具200は、交流電源1に接続され、交流電源1から出力される交流電流を平滑化する入力フィルタ2を介して交流電源1から供給される電力を光源8に入力可能な直流電流に変換して出力する点灯装置100と、点灯装置100から供給される電力により点灯する光源8と、光源8の点灯、消灯又は調光を行うための調光信号を出力する調光器10とを備える。光源8は、複数のLEDを直接に接続したLED群で構成される。LED群の一端は正極側直流母線Pに接続され、LED群の他端は負極側直流母線Nに接続される。
Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a lighting device and a lighting fixture according to the first embodiment. The luminaire 200 is connected to the AC power source 1 and converts the power supplied from the AC power source 1 through the input filter 2 that smoothes the AC current output from the AC power source 1 into a DC current that can be input to the light source 8. The lighting device 100 that outputs the light, the light source 8 that is turned on by the power supplied from the lighting device 100, and the dimmer 10 that outputs a dimming signal for turning on, turning off, or dimming the light source 8. . The light source 8 is composed of an LED group in which a plurality of LEDs are directly connected. One end of the LED group is connected to the positive side DC bus P, and the other end of the LED group is connected to the negative side DC bus N.
 点灯装置100は、入力フィルタ2と、入力フィルタ2に接続される整流回路3と、整流回路3に並列接続されるコンデンサ4と、直流変換回路30と、光源8に流れる電流を検出する電流検出部11と、PFC回路5及び電流制御部7を制御するための制御部9とを備える。 The lighting device 100 includes an input filter 2, a rectifier circuit 3 connected to the input filter 2, a capacitor 4 connected in parallel to the rectifier circuit 3, a DC conversion circuit 30, and a current detection that detects a current flowing through the light source 8. And a control unit 9 for controlling the PFC circuit 5 and the current control unit 7.
 直流変換回路30は、交流電源1から入力される電流の高調波を抑制して力率を改善すると共に、整流回路3から出力される電力を直流電力に変換して光源8に供給する機能を有する。直流変換回路30は、交流電源1から入力される電流の高調波を抑制して力率を改善するためのPFC回路5と、PFC回路5の出力電圧を平滑する平滑コンデンサ6と、光源8に出力する電流の大きさを制御する電流制御部7とを備える。 The DC conversion circuit 30 has a function of improving the power factor by suppressing harmonics of the current input from the AC power supply 1 and converting the power output from the rectifier circuit 3 into DC power and supplying it to the light source 8. Have. The DC conversion circuit 30 includes a PFC circuit 5 for improving the power factor by suppressing harmonics of the current input from the AC power supply 1, a smoothing capacitor 6 for smoothing the output voltage of the PFC circuit 5, and a light source 8. And a current control unit 7 for controlling the magnitude of the output current.
 交流電源1と整流回路3との間に配置される入力フィルタ2は、コイル21及びコンデンサ22を有し、交流電源1から出力される電流に重畳している高周波ノイズを低減する。コイル21は交流電源1に直列接続される。コイル21の一端は交流電源1の一端に接続され、コイル21の他端はコンデンサ22及び整流回路3に接続される。コンデンサ22の他端は、交流電源1及び整流回路3に接続される。 The input filter 2 disposed between the AC power supply 1 and the rectifier circuit 3 includes a coil 21 and a capacitor 22 and reduces high-frequency noise superimposed on the current output from the AC power supply 1. The coil 21 is connected in series to the AC power source 1. One end of the coil 21 is connected to one end of the AC power supply 1, and the other end of the coil 21 is connected to the capacitor 22 and the rectifier circuit 3. The other end of the capacitor 22 is connected to the AC power source 1 and the rectifier circuit 3.
 整流回路3は、入力フィルタ2とPFC回路5との間に配置され、交流電源1から供給される交流電力を直流電力に変換する。整流回路3は4つのダイオードを組み合わせたダイオードブリッジで構成されている。なお整流回路3の構成はこれに限定されるものではなく、単方向導通素子であるMOSFETを組み合わせて構成したものでもよい。 The rectifier circuit 3 is disposed between the input filter 2 and the PFC circuit 5 and converts AC power supplied from the AC power source 1 into DC power. The rectifier circuit 3 is composed of a diode bridge in which four diodes are combined. The configuration of the rectifier circuit 3 is not limited to this, and may be configured by combining MOSFETs that are unidirectional conducting elements.
 コンデンサ4は整流回路3の出力に並列接続されており、整流回路3の出力電圧を平滑する。コンデンサ4の一端は正極側直流母線Pに接続され、コンデンサ4の他端は負極側直流母線Nに接続される。 The capacitor 4 is connected in parallel to the output of the rectifier circuit 3, and smoothes the output voltage of the rectifier circuit 3. One end of the capacitor 4 is connected to the positive side DC bus P, and the other end of the capacitor 4 is connected to the negative side DC bus N.
 PFC回路5は、整流回路3と電流制御部7との間に配置される。PFC回路5は、スイッチング素子であるMOSFET51と、コイル52と、ダイオード53とを有する。PFC回路5は、制御部9によってMOSFET51がオンオフ制御されることにより、整流回路3の出力電圧を昇圧し、昇圧した電圧を平滑コンデンサ6に出力する。またPFC回路5は、後述する制御により、入力電流の高調波を抑制し、力率改善する機能を持つ。実施の形態1では、PFC回路5を昇圧チョッパ回路で構成した例を説明する。なおPFC回路5は、昇圧チョッパ回路の他にも、昇降圧チョッパ回路、フライバック回路、フライフォワード回路、SEPIC(Single Ended Primary Inductor Converter)、Zetaコンバータ又はCukコンバータといった回路で構成してもよい。 The PFC circuit 5 is disposed between the rectifier circuit 3 and the current control unit 7. The PFC circuit 5 includes a MOSFET 51 that is a switching element, a coil 52, and a diode 53. The PFC circuit 5 boosts the output voltage of the rectifier circuit 3 by turning on and off the MOSFET 51 by the control unit 9, and outputs the boosted voltage to the smoothing capacitor 6. Further, the PFC circuit 5 has a function of suppressing the harmonics of the input current and improving the power factor by the control described later. In the first embodiment, an example in which the PFC circuit 5 is configured by a boost chopper circuit will be described. In addition to the step-up chopper circuit, the PFC circuit 5 may be configured by a circuit such as a step-up / step-down chopper circuit, a flyback circuit, a flyforward circuit, a SEPIC (Single Ended Primary Inverter Converter), a Zeta converter, or a Cuk converter.
 コイル52は、正極側直流母線Pにおいて、コンデンサ4とMOSFET51との間に配置される。不図示のコアに絶縁性ワイヤを巻くことにより、コイル52には1次巻線52a及び2次巻線52bが形成される。1次巻線52aの一端はコンデンサ4の一端に接続される。1次巻線52aの他端はダイオード53のアノードに接続される。2次巻線52bの一端は制御部9に接続され、2次巻線52bの他端は負極側直流母線Nに接続される。1次巻線52aには、MOSFET51のオンオフ動作に伴い、極性が異なる電圧が印加される。2次巻線52bに発生する電圧は、1次巻線52aの印加電圧と巻数比nとに応じた電圧に等しい。 The coil 52 is disposed between the capacitor 4 and the MOSFET 51 on the positive side DC bus P. A primary winding 52 a and a secondary winding 52 b are formed in the coil 52 by winding an insulating wire around a core (not shown). One end of the primary winding 52 a is connected to one end of the capacitor 4. The other end of the primary winding 52 a is connected to the anode of the diode 53. One end of the secondary winding 52b is connected to the control unit 9, and the other end of the secondary winding 52b is connected to the negative-side DC bus N. A voltage having a different polarity is applied to the primary winding 52a as the MOSFET 51 is turned on / off. The voltage generated in the secondary winding 52b is equal to the voltage corresponding to the applied voltage of the primary winding 52a and the turns ratio n.
 MOSFET51のドレインは、正極側直流母線Pにおいて、1次巻線52aとダイオード53のアノードとに接続される。MOSFET51のソースは、負極側直流母線Nにおいて、コンデンサ4の他端と、2次巻線52bの他端と平滑コンデンサ6の他端とに接続される。MOSFET51のゲートは制御部9に接続される。MOSFET51のゲートには、制御部9から出力される制御信号が入力される。制御信号が入力されることによりMOSFET51のオンオフ制御が行われる。 The drain of the MOSFET 51 is connected to the primary winding 52 a and the anode of the diode 53 in the positive side DC bus P. The source of the MOSFET 51 is connected to the other end of the capacitor 4, the other end of the secondary winding 52 b, and the other end of the smoothing capacitor 6 on the negative DC bus N. The gate of the MOSFET 51 is connected to the control unit 9. A control signal output from the control unit 9 is input to the gate of the MOSFET 51. On / off control of the MOSFET 51 is performed by inputting the control signal.
 ダイオード53は、正極側直流母線Pにおいて、MOSFET51と平滑コンデンサ6との間に配置される。ダイオード53のアノードはコイル52及びMOSFET51に接続され、ダイオード53のカソードは平滑コンデンサ6に接続される。 The diode 53 is disposed between the MOSFET 51 and the smoothing capacitor 6 in the positive side DC bus P. The anode of the diode 53 is connected to the coil 52 and the MOSFET 51, and the cathode of the diode 53 is connected to the smoothing capacitor 6.
 平滑コンデンサ6は、PFC回路5と電流制御部7との間に配置される。平滑コンデンサ6の一端は正極側直流母線Pに接続され、平滑コンデンサ6の他端は負極側直流母線Nに接続される。 The smoothing capacitor 6 is disposed between the PFC circuit 5 and the current control unit 7. One end of the smoothing capacitor 6 is connected to the positive side DC bus P, and the other end of the smoothing capacitor 6 is connected to the negative side DC bus N.
 電流検出部11は、光源8に流れる電流を検出し、検出された電流値に対応した電流情報を制御部9に出力する。電流検出部11としては、シャント抵抗又はホールセンサを用いて電流を検出する構成を例示できる。 The current detector 11 detects a current flowing through the light source 8 and outputs current information corresponding to the detected current value to the controller 9. As the current detection unit 11, a configuration in which a current is detected using a shunt resistor or a hall sensor can be exemplified.
 制御部9は、目標値出力部91、ゼロ電流検出部92、スイッチング制御部93、電流入力部94及び電圧検出部95を備える。 The control unit 9 includes a target value output unit 91, a zero current detection unit 92, a switching control unit 93, a current input unit 94, and a voltage detection unit 95.
 目標値出力部91には調光器10が接続され、目標値出力部91は、調光器10から出力される調光信号の種類に対応した出力電流目標値を決定し、決定した出力電流目標値をスイッチング制御部93に出力する。出力電流目標値は、点灯装置100が光源8に出力する電流目標値を指定する信号である。 The target value output unit 91 is connected to the dimmer 10, and the target value output unit 91 determines an output current target value corresponding to the type of the dimming signal output from the dimmer 10, and the determined output current The target value is output to the switching control unit 93. The output current target value is a signal that specifies a current target value that the lighting device 100 outputs to the light source 8.
 電圧検出部95は、平滑コンデンサ6の電圧を検出し、検出した電圧の値に対応した電圧情報をスイッチング制御部93に出力する。電圧検出部95としては分圧回路を例示できる。当該分圧回路は、2つの抵抗を直列接続した直列抵抗体の一端が正極側直流母線Pに接続されると共に、当該直列抵抗体の他端が負極側直流母線Nに接続されることで、平滑コンデンサ6に印加される電圧を分圧する回路である。 The voltage detector 95 detects the voltage of the smoothing capacitor 6 and outputs voltage information corresponding to the detected voltage value to the switching controller 93. An example of the voltage detector 95 is a voltage dividing circuit. In the voltage dividing circuit, one end of a series resistor in which two resistors are connected in series is connected to the positive side DC bus P, and the other end of the series resistor is connected to the negative side DC bus N. This circuit divides the voltage applied to the smoothing capacitor 6.
 スイッチング制御部93は、目標値出力部91から出力された出力電流目標値と、電流入力部94に入力された電流情報とに基づき、電流制御部7を制御するための制御信号を出力する。またスイッチング制御部93は、PFC回路5の出力電圧目標値を予め記憶しており、少なくとも、電圧検出部95から出力された電圧情報と、記憶された出力電圧目標値とに基づき、PFC回路5を制御するための制御信号を出力する。 The switching control unit 93 outputs a control signal for controlling the current control unit 7 based on the output current target value output from the target value output unit 91 and the current information input to the current input unit 94. The switching control unit 93 stores the output voltage target value of the PFC circuit 5 in advance, and based on at least the voltage information output from the voltage detection unit 95 and the stored output voltage target value. A control signal for controlling the signal is output.
 電流制御部7は、スイッチング制御部93から出力された制御信号に基づき、PFC回路5から出力された直流電圧を光源8に入力可能な直流電流に変換する。 The current control unit 7 converts the DC voltage output from the PFC circuit 5 into a DC current that can be input to the light source 8 based on the control signal output from the switching control unit 93.
 図2は図1に示す電流制御部の構成を示す図である。図2に示す電流制御部7は、降圧チョッパ回路で構成されているが、降圧チョッパ回路の他にも、昇降圧チョッパ回路、フライバック回路、フライフォワード回路、SEPIC、Zetaコンバータ又はCukコンバータといった回路で構成されたものでもよい。 FIG. 2 is a diagram showing a configuration of the current control unit shown in FIG. The current control unit 7 shown in FIG. 2 includes a step-down chopper circuit. In addition to the step-down chopper circuit, a circuit such as a step-up / step-down chopper circuit, a flyback circuit, a fly-forward circuit, a SEPIC, a Zeta converter, or a Cuk converter is used. It may be composed of
 電流制御部7は、MOSFET71、コイル72、ダイオード73及びコンデンサ74により構成される。MOSFET71は正極側直流母線Pに配置される。MOSFET71のドレインは、図1に示す平滑コンデンサ6の一端とダイオード53のカソードとに接続される。MOSFET71のソースは、ダイオード73のカソードとコイル72の一端とに接続される。MOSFET71のゲートはスイッチング制御部93に接続される。MOSFET71のゲートには、スイッチング制御部93から出力される制御信号が入力される。当該制御信号はMOSFET71をオンオフ制御するための信号である。 The current control unit 7 includes a MOSFET 71, a coil 72, a diode 73, and a capacitor 74. MOSFET 71 is arranged on positive side DC bus P. The drain of the MOSFET 71 is connected to one end of the smoothing capacitor 6 and the cathode of the diode 53 shown in FIG. The source of the MOSFET 71 is connected to the cathode of the diode 73 and one end of the coil 72. The gate of the MOSFET 71 is connected to the switching control unit 93. A control signal output from the switching control unit 93 is input to the gate of the MOSFET 71. The control signal is a signal for controlling on / off of the MOSFET 71.
 コイル72の一端は、MOSFET71のソースとダイオード73のカソードとに接続される。コイル72の他端は、コンデンサ74の一端と図1に示す光源8の一端とに接続される。ダイオード73のカソードは、MOSFET71のソースとコイル72の一端とに接続される。ダイオード73のアノードは、図1に示す平滑コンデンサ6の他端とコンデンサ74の他端と図1に示す光源8の他端とに接続される。 One end of the coil 72 is connected to the source of the MOSFET 71 and the cathode of the diode 73. The other end of the coil 72 is connected to one end of the capacitor 74 and one end of the light source 8 shown in FIG. The cathode of the diode 73 is connected to the source of the MOSFET 71 and one end of the coil 72. The anode of the diode 73 is connected to the other end of the smoothing capacitor 6 shown in FIG. 1, the other end of the capacitor 74, and the other end of the light source 8 shown in FIG.
 図3は光源に流れる電流とコイルに流れる電流とMOSFETの制御信号との関係を示すタイミングチャートである。図3には上から順に、光源8に流れる電流と、コイル72に流れる電流と、MOSFET71の制御信号とが示される。横軸は時間を表す。 FIG. 3 is a timing chart showing the relationship between the current flowing through the light source, the current flowing through the coil, and the control signal of the MOSFET. FIG. 3 shows the current flowing through the light source 8, the current flowing through the coil 72, and the control signal of the MOSFET 71 in order from the top. The horizontal axis represents time.
 スイッチング周期Tswは、MOSFET71の制御信号がオフからオンに変化した時点から、再びMOSFET71の制御信号がオフからオンに変化するまでの時間に等しい。スイッチング周期Tswは、予めスイッチング制御部93に設定されている。オン時間Tonは、MOSFET71の制御信号がオフからオンに変化した時点から、オンからオフに変化するまでの時間に等しい。 The switching cycle Tsw is equal to the time from when the control signal of the MOSFET 71 changes from OFF to ON until the control signal of the MOSFET 71 changes from OFF to ON again. The switching period Tsw is set in the switching control unit 93 in advance. The on time Ton is equal to the time from when the control signal of the MOSFET 71 changes from off to on until it changes from on to off.
 MOSFET71の制御信号がオフからオンの状態に変化すると、MOSFET71がオン状態になるため、平滑コンデンサ6、MOSFET71、コイル72及びコンデンサ74に電流が流れる電流経路が形成され、図3に示すようにコイル72に流れる電流が増加する。 When the control signal of the MOSFET 71 changes from OFF to ON, the MOSFET 71 is turned ON, so that a current path through which current flows through the smoothing capacitor 6, the MOSFET 71, the coil 72, and the capacitor 74 is formed, as shown in FIG. The current flowing through 72 increases.
 MOSFET71の制御信号がオンからオフの状態に変化すると、MOSFET71がオフ状態になるため、コイル72、コンデンサ74及びダイオード73に電流が流れる電流経路が形成され、図3に示すコイル72に流れる電流がゼロまで減少する。スイッチング周期Tswが経過した時点で、MOSFET71の制御信号がオフからオンに変化する。これによりMOSFET71が再びオン状態になる。 When the control signal of the MOSFET 71 changes from on to off, the MOSFET 71 is turned off, so that a current path through which current flows through the coil 72, the capacitor 74, and the diode 73 is formed, and the current flowing through the coil 72 shown in FIG. Decrease to zero. When the switching cycle Tsw elapses, the control signal of the MOSFET 71 changes from off to on. As a result, the MOSFET 71 is turned on again.
 このときコイル72に流れる電流は三角波状の波形になるが、光源8に出力される電流は、コンデンサ74により平滑化され、コイル72に流れる電流の平均値が電流制御部7から出力される。 At this time, the current flowing through the coil 72 has a triangular waveform, but the current output to the light source 8 is smoothed by the capacitor 74, and the average value of the current flowing through the coil 72 is output from the current control unit 7.
 光源8を調光するために光源8に流れる電流を制御する場合、スイッチング制御部93は、MOSFET71をターンオンするスイッチング周期Tswを一定とし、出力電流の目標値によってオン時間Tonを変化させる。このようにオン時間Tonを調整することにより特定の出力を得る制御方法は、スイッチング周期Tswに対するオン時間Tonの割合をデューティーと呼ぶことから、デューティー制御と呼ばれる。 When controlling the current flowing through the light source 8 in order to dim the light source 8, the switching control unit 93 makes the switching period Tsw for turning on the MOSFET 71 constant, and changes the on-time Ton according to the target value of the output current. The control method for obtaining a specific output by adjusting the on-time Ton in this way is called duty control because the ratio of the on-time Ton to the switching period Tsw is called duty.
 次にPFC回路5の動作を詳細に説明する。 Next, the operation of the PFC circuit 5 will be described in detail.
 図4は図1に示すPFC回路を構成するコイルに流れる電流とMOSFETのドレイン電圧とMOSFETのゲート電圧との関係を示すタイミングチャートである。図4には上から順に、点灯装置100に入力される交流電源1の電流と、コイル52に流れる電流と、MOSFET51のドレイン電圧と、MOSFET51のゲート電圧とが示される。横軸は時間を表す。図4では、点灯装置100に入力される交流電源1の電流が「入力電流」として示される。 FIG. 4 is a timing chart showing the relationship between the current flowing through the coil constituting the PFC circuit shown in FIG. 1, the drain voltage of the MOSFET, and the gate voltage of the MOSFET. FIG. 4 shows, in order from the top, the current of the AC power source 1 input to the lighting device 100, the current flowing through the coil 52, the drain voltage of the MOSFET 51, and the gate voltage of the MOSFET 51. The horizontal axis represents time. In FIG. 4, the current of the AC power supply 1 input to the lighting device 100 is indicated as “input current”.
 図4では、説明の便宜上、MOSFET51のゲート電圧がオンオフされる周期を、実際よりも長く記載している。MOSFET51のゲート電圧がオンオフされる周期は、MOSFET51のゲート電圧がオフからオンに変化した時点から、再びMOSFET51のゲート電圧がオフからオンに変化するまでの時間に等しい。 In FIG. 4, for convenience of explanation, the cycle in which the gate voltage of the MOSFET 51 is turned on and off is shown longer than the actual period. The period when the gate voltage of the MOSFET 51 is turned on and off is equal to the time from when the gate voltage of the MOSFET 51 changes from off to on until when the gate voltage of the MOSFET 51 changes from off to on again.
 MOSFET51がオンされたとき、交流電源1、整流回路3、コイル52及びMOSFET51により閉回路が形成され、交流電源1がコイル52を介して短絡される。そのため閉回路に電源電流が流れ、コイル52に流れる電流が増加し、コイル52にエネルギーが蓄積される。 When the MOSFET 51 is turned on, a closed circuit is formed by the AC power source 1, the rectifier circuit 3, the coil 52 and the MOSFET 51, and the AC power source 1 is short-circuited via the coil 52. As a result, the power source current flows through the closed circuit, the current flowing through the coil 52 increases, and energy is stored in the coil 52.
 スイッチング制御部93に設定されたオン時間が経過すると、MOSFET51がオフされることにより、コイル52、ダイオード53及び平滑コンデンサ6の閉回路が形成される。この閉回路においてコイル52に蓄積されたエネルギーが放出され、平滑コンデンサ6が充電される。 When the ON time set in the switching control unit 93 has elapsed, the MOSFET 51 is turned off, thereby forming a closed circuit of the coil 52, the diode 53, and the smoothing capacitor 6. In this closed circuit, the energy accumulated in the coil 52 is released, and the smoothing capacitor 6 is charged.
 コイル52に流れる電流がゼロになった時点から遅延時間Tdelayが経過するまで、MOSFET51のオフ状態は維持され、遅延時間Tdelayが経過したときにMOSFET51は再びオン状態になる。すなわち、コイル52に流れる電流がゼロになった時点から遅延時間Tdelayが経過した時点まで、MOSFET51の制御信号はオフ状態を維持し、遅延時間Tdelayが経過した時点でMOSFET51の制御信号はオン状態に変化する。 The OFF state of the MOSFET 51 is maintained from when the current flowing through the coil 52 becomes zero until the delay time Tdelay elapses, and when the delay time Tdelay elapses, the MOSFET 51 is turned on again. That is, the control signal of the MOSFET 51 remains off until the delay time Tdelay elapses from the time when the current flowing through the coil 52 becomes zero, and the control signal of the MOSFET 51 is turned on when the delay time Tdelay elapses. Change.
 MOSFET51の一連のオンオフ動作により、コイル52に流れる電流は、三角波状の波形となり、その頂点が点線で示すような正弦波の包絡線になる。 Due to the series of on / off operations of the MOSFET 51, the current flowing through the coil 52 has a triangular waveform, and the apex thereof becomes a sine wave envelope as indicated by a dotted line.
 このとき、交流電源1から入力される電流は、入力フィルタ2により平滑化され、コイル21に流れるコイル電流の平均値が入力され、正弦波状の電流波形となる。 At this time, the current input from the AC power source 1 is smoothed by the input filter 2, and the average value of the coil current flowing through the coil 21 is input to form a sine wave current waveform.
 制御部9が平滑コンデンサ6の印加電圧を検出して、検出された電圧が目標値に追従するようフィードバック制御されることで、MOSFET51のオン時間が制御される。 The control unit 9 detects the voltage applied to the smoothing capacitor 6 and performs feedback control so that the detected voltage follows the target value, whereby the on-time of the MOSFET 51 is controlled.
 MOSFET51のオン時間をフィードバック制御する際、オン時間が大きく変化してしまうと、コイル52に流れる電流の頂点の包絡線が正弦波にならず、交流電源1の入力電流を正弦波状にすることができない。そのため制御部9では、フィードバック制御の応答時間が、フィードバック制御のループゲインを交流電源1の1周期の1/2周期以上で1倍(0dB)以下となるように、設定される。言い換えると、フィードバック制御の応答時間は、交流電源1の周波数の2倍以下の周波数で1倍(0dB)以下となるように設定される。 When the on-time of the MOSFET 51 is feedback-controlled, if the on-time changes greatly, the envelope of the peak of the current flowing through the coil 52 does not become a sine wave, and the input current of the AC power supply 1 may be made a sine wave. Can not. Therefore, in the control unit 9, the response time of the feedback control is set so that the loop gain of the feedback control becomes 1 time (0 dB) or less after being 1/2 of 1 cycle of the AC power supply 1. In other words, the response time of the feedback control is set to be 1 (0 dB) or less at a frequency that is 2 times or less of the frequency of the AC power supply 1.
 具体的に説明すると、電源周波数が50Hzの場合、電源周波数の半周期(半波)の周波数100Hz以下、すなわち周期10msec以上で、フィードバック制御のループゲインを1倍(0dB)以下とすることにより、フィードバック制御は電源周期の1/2より短い周期で応答しないように設定される。これにより電源周期の1/2周期以内においては、MOSFET51のオン時間の変動が抑制され、コイル52に流れる電流の頂点の包絡線が正弦波状の波形となる。 More specifically, when the power supply frequency is 50 Hz, the feedback control loop gain is set to 1 (0 dB) or less at a frequency of 100 Hz or less of a half cycle (half wave) of the power supply frequency, that is, a cycle of 10 msec or more. The feedback control is set so as not to respond in a cycle shorter than ½ of the power cycle. As a result, fluctuations in the ON time of the MOSFET 51 are suppressed within a half cycle of the power supply cycle, and the envelope at the apex of the current flowing through the coil 52 becomes a sine wave waveform.
 またフィードバック制御において、オン時間の更新周期を、交流電源1の周期の半分に相当する周期、又は交流電源1の周期の半分に相当する周期よりも長い周期とすることによっても、同様の効果を得ることができる。 In the feedback control, the same effect can be obtained by setting the on-time update cycle to a cycle corresponding to half the cycle of the AC power supply 1 or a cycle longer than the cycle corresponding to half the cycle of the AC power supply 1. Obtainable.
 上記の特許文献1に開示される技術では、遅延時間Tdelayを設けない電流臨界モード制御により、MOSFET51がスイッチング制御されるため、コイル52に流れる電流の平均値が完全な正弦波状になり、高い力率改善効果が期待できる。 In the technique disclosed in Patent Document 1 described above, the MOSFET 51 is switching-controlled by current critical mode control without providing the delay time Tdelay. Therefore, the average value of the current flowing through the coil 52 becomes a complete sine wave, and high power A rate improvement effect can be expected.
 これに対して実施の形態1に係る点灯装置100は、遅延時間Tdelayを設け、電流不連続モード制御によりMOSFET51をスイッチング制御することで、電流臨界モード制御する場合に比べて、スイッチング周波数を低くすることができるため、MOSFET51で発生するスイッチング損失を低減できる。 On the other hand, the lighting device 100 according to the first embodiment provides the delay time Tdelay and performs switching control of the MOSFET 51 by current discontinuous mode control, thereby lowering the switching frequency compared to the case of current critical mode control. Therefore, the switching loss generated in the MOSFET 51 can be reduced.
 このとき遅延時間Tdelayを長くし過ぎると、コイル52の電流平均値が正弦波でなくなり、力率改善効果が低下して高調波が増加する。そのため遅延時間Tdelayは、高調波の増加が許容できる範囲内に設定する必要がある。高調波の増加が許容できる範囲の一例としては、日本工業規格で定められる電流高調波限度値以内とすることが挙げられる。具体的な遅延時間Tdelayの設け方としては、MOSFET51のドレイン電圧が自由振動している期間において、制御部9は、MOSFET51の電圧振動のボトム付近でMOSFET51をオンさせることで、ドレイン電圧の急峻な変動を抑制し、スイッチングに起因するノイズを抑制できる。また、MOSFET51の電圧振動のボトムの少なくとも2回目以降のボトムにおいて制御部9がMOSFET51をオンすることで、確実に遅延時間を設けることができる。 At this time, if the delay time Tdelay is made too long, the current average value of the coil 52 is not a sine wave, the power factor improving effect is lowered, and the harmonics are increased. Therefore, it is necessary to set the delay time Tdelay within a range in which an increase in harmonics can be allowed. An example of a range in which an increase in harmonics is allowable is within a current harmonic limit value defined by Japanese Industrial Standards. As a specific method of providing the delay time Tdelay, during the period in which the drain voltage of the MOSFET 51 is free oscillating, the control unit 9 turns on the MOSFET 51 near the bottom of the voltage oscillation of the MOSFET 51 so that the drain voltage has a steep drain voltage. It is possible to suppress fluctuations and suppress noise caused by switching. In addition, the control unit 9 turns on the MOSFET 51 at least at the second and subsequent bottoms of the bottom of the voltage oscillation of the MOSFET 51, so that a delay time can be provided with certainty.
 光源8を調光する場合、交流電源1の入力電流を小さくするため、スイッチング制御部93は、MOSFET51のオン時間を短くするように制御を行う。 When the light source 8 is dimmed, the switching control unit 93 performs control so as to shorten the ON time of the MOSFET 51 in order to reduce the input current of the AC power supply 1.
 図5は遅延時間を設けずに電流臨界モード制御で調光した場合の波形を示す図であり、図6は遅延時間を設けて調光した場合の波形を示す図である。図5及び図6は、光源8を調光する際におけるPFC回路5のスイッチング動作の概要を説明するためのものである。図5及び図6のそれぞれには、図4と同様に、交流電源1の入力電流と、コイル52に流れる電流と、MOSFET51のドレイン電圧と、MOSFET51のゲート電圧とが示される。横軸は時間を表す。 FIG. 5 is a diagram showing a waveform when dimming with current critical mode control without providing a delay time, and FIG. 6 is a diagram showing a waveform when dimming with a delay time. 5 and 6 are for explaining an outline of the switching operation of the PFC circuit 5 when the light source 8 is dimmed. Each of FIGS. 5 and 6 shows the input current of the AC power supply 1, the current flowing through the coil 52, the drain voltage of the MOSFET 51, and the gate voltage of the MOSFET 51, as in FIG. 4. The horizontal axis represents time.
 図6に示すように遅延時間Tdelayを設けて調光した場合、図5に示すように電流臨界モード制御で調光した場合に比べて、MOSFET51のスイッチング周波数が低下してスイッチング損失を低減できる。 As shown in FIG. 6, when the light is adjusted with the delay time Tdelay, the switching frequency of the MOSFET 51 is lowered and the switching loss can be reduced as compared with the case where the light is controlled by the current critical mode control as shown in FIG.
 図7は調光率に応じて変化するMOSFETのオン時間及びスイッチング周波数の特性を示す図である。図7には上から順に、遅延時間Tdelayと、MOSFET51のオン時間と、MOSFET51を制御する制御信号のスイッチング周波数と、光源8の調光率とが示される。 FIG. 7 is a graph showing the on-time and switching frequency characteristics of the MOSFET, which change according to the dimming rate. FIG. 7 shows, in order from the top, the delay time Tdelay, the ON time of the MOSFET 51, the switching frequency of the control signal for controlling the MOSFET 51, and the dimming rate of the light source 8.
 点線は、電流臨界モード制御が行われている場合に調光率を変化させたときの、遅延時間Tdelay、MOSFET51のオン時間及びスイッチング周波数を表す。実線は、遅延時間を設定した電流不連続モード制御が行われている場合に調光率を変化させたときの、遅延時間Tdelay、MOSFET51のオン時間及びスイッチング周波数を表す。 The dotted line represents the delay time Tdelay, the ON time of the MOSFET 51, and the switching frequency when the dimming rate is changed when the current critical mode control is performed. A solid line represents the delay time Tdelay, the ON time of the MOSFET 51, and the switching frequency when the dimming rate is changed when the current discontinuous mode control in which the delay time is set is performed.
 遅延時間Tdelayを設けて電流不連続モード制御することで、電流臨界モード制御と比較して、調光時におけるスイッチング周波数の上昇を抑制することができ、スイッチング損失を低減できる。また、MOSFET51のオン時間を長くすることができ、より確実にMOSFET51をオンオフ制御できる。 By providing the delay time Tdelay and performing the current discontinuous mode control, an increase in switching frequency during dimming can be suppressed and switching loss can be reduced as compared with current critical mode control. Further, the ON time of the MOSFET 51 can be lengthened, and the MOSFET 51 can be controlled on and off more reliably.
 また遅延時間Tdelayは一定の長さではなく、調光率に応じて変化させることができる。図8は調光率に応じて遅延時間を変化させた場合のMOSFETのオン時間とスイッチング周波数を示す第1の図である。 Also, the delay time Tdelay is not a fixed length but can be changed according to the dimming rate. FIG. 8 is a first diagram showing the MOSFET on-time and switching frequency when the delay time is changed in accordance with the dimming rate.
 図8に示すように調光率には閾値が設けられ、制御部9は、調光率が閾値を上回る場合には、遅延時間を一定の第1の遅延時間Tdelay1stとし、調光率が閾値以下である場合には、遅延時間を第2の遅延時間Tdelay2ndとする。第2の遅延時間Tdelay2ndは、第1の遅延時間Tdelay1stよりも長い時間であって、調光率が低下するほど長くなる時間である。 As shown in FIG. 8, a threshold value is provided for the dimming rate, and when the dimming rate exceeds the threshold value, the control unit 9 sets the delay time as the first delay time Tdelay 1st, and the dimming rate is the threshold value. In the following cases, the delay time is the second delay time Tdelay2nd. The second delay time Tdelay2nd is longer than the first delay time Tdelay1st, and is longer as the dimming rate decreases.
 図8に示す閾値、第1の遅延時間Tdelay1st及び第2の遅延時間Tdelay2ndは、予め制御部9に設定されているものとする。第1の遅延時間Tdelay1stは、閾値を上回る調光率が入力されたときに設定され、第2の遅延時間Tdelay2ndは、閾値以下の調光率が入力されたときに設定される。 Suppose that the threshold, the first delay time Tdelay1st, and the second delay time Tdelay2nd shown in FIG. 8 are set in the control unit 9 in advance. The first delay time Tdelay1st is set when a dimming rate exceeding the threshold is input, and the second delay time Tdelay2nd is set when a dimming rate less than the threshold is input.
 MOSFET51のオン時間が短くなりすぎると、MOSFET51が正常にオンオフ動作できなくなることがある。MOSFET51が正常にオンオフ動作できなくなるオン時間の長さは例えば0.2usec以下である。そのため制御部9には最小オン時間Ton_minが記憶されており、光源8を調光する際、MOSFET51のオン時間が最小オン時間Ton_minよりも短くならないように調光制御することができる。 If the ON time of the MOSFET 51 becomes too short, the MOSFET 51 may not be able to normally operate on and off. The length of the on time during which the MOSFET 51 cannot normally be turned on / off is, for example, 0.2 usec or less. Therefore, the control unit 9 stores the minimum on-time Ton_min. When the light source 8 is dimmed, the dimming control can be performed so that the on-time of the MOSFET 51 is not shorter than the minimum on-time Ton_min.
 図9は調光率に応じて遅延時間を変化させた場合のMOSFETのオン時間とスイッチング周波数を示す第2の図である。図9に示すように調光率に対して複数の閾値1,2,3が設定されている。複数の閾値1,2,3は、閾値3、閾値2及び閾値1の順で高い値となる。また図9に示すように複数の閾値1,2,3に対応する複数の遅延時間Tdelay1,2,3,4が設定されている。複数の閾値1,2,3及び複数の遅延時間Tdelay1,2,3,4は、制御部9に設定されているものとする。 FIG. 9 is a second diagram showing the MOSFET on-time and switching frequency when the delay time is changed in accordance with the dimming rate. As shown in FIG. 9, a plurality of threshold values 1, 2, and 3 are set for the dimming rate. The plurality of thresholds 1, 2, and 3 are higher in the order of threshold 3, threshold 2, and threshold 1. Further, as shown in FIG. 9, a plurality of delay times Tdelay 1, 2, 3, 4 corresponding to a plurality of threshold values 1, 2, 3 are set. It is assumed that a plurality of threshold values 1, 2, 3 and a plurality of delay times Tdelay 1, 2, 3, 4 are set in the control unit 9.
 遅延時間Tdelay4は、閾値3以下の調光率が入力されたときに設定される。遅延時間Tdelay3は、閾値3を上回りかつ閾値2以下の調光率が入力されたときに設定される。遅延時間Tdelay2は、閾値2を上回りかつ閾値1以下の調光率が入力されたときに設定される。遅延時間Tdelay1は、閾値1を上回る調光率が入力されたときに設定される。 Delay time Tdelay4 is set when a dimming rate of threshold 3 or less is input. The delay time Tdelay3 is set when a dimming rate that exceeds the threshold 3 and is equal to or less than the threshold 2 is input. The delay time Tdelay2 is set when a dimming rate that exceeds the threshold 2 and is equal to or less than the threshold 1 is input. The delay time Tdelay1 is set when a dimming rate exceeding the threshold value 1 is input.
 制御部9は、調光率に複数の閾値を設けて、隣接する閾値同士の間の範囲に応じて互いに異なる長さの複数の遅延時間を用いてスイッチング素子を制御する。具体的には、遅延時間Tdelay1を設けて点灯している状態から、光源8の電流が低下する方向に調光されて、調光率が閾値1に達したとき、MOSFET51のオン時間が最小オン時間Ton_minまで短くなると、制御部9は、遅延時間をTdelay1からTdelay2に増加させる。これにより、MOSFET51のオン時間が最小オン時間Ton_minよりも短くなることを防止できる。 The control unit 9 provides a plurality of threshold values for the dimming rate, and controls the switching elements using a plurality of delay times having different lengths according to a range between adjacent threshold values. Specifically, when the delay time Tdelay1 is provided and the light is dimmed in the direction in which the current of the light source 8 decreases and the dimming rate reaches the threshold value 1, the on-time of the MOSFET 51 is the minimum on-time. When the time is shortened to the time Ton_min, the control unit 9 increases the delay time from Tdelay1 to Tdelay2. This can prevent the on time of the MOSFET 51 from becoming shorter than the minimum on time Ton_min.
 図10は図9に示す調光率の閾値1を境にして、遅延時間をTdelay1からTdelay2に延長する場合の、遅延時間、MOSFETのオン時間及び光源の調光率の時間変化を示す図である。 FIG. 10 is a diagram showing changes over time in delay time, MOSFET on-time, and light source dimming rate when the delay time is extended from Tdelay1 to Tdelay2 with threshold value 1 of dimming rate shown in FIG. is there.
 遅延時間Tdelayを急激に延長すると、MOSFET51のスイッチング周波数が急変し、PFC回路5の出力が変動し、平滑コンデンサ6が電圧変動する影響により、後段に接続される電流制御部7の出力電流が一定値とならず、光源8を安定して点灯することができない。そこで、遅延時間Tdelayを延長する場合、遅延時間Tdelayの変化量最大値Tstepを設けると共に、遅延時間Tdelayを変化させずに維持する維持時間Tkを設けることによって、遅延時間Tdelayの時間変化を遅くすることができる。この制御を行うことで、MOSFET51のスイッチング周波数が急変することを抑制できる。 When the delay time Tdelay is abruptly extended, the switching frequency of the MOSFET 51 suddenly changes, the output of the PFC circuit 5 fluctuates, and the voltage of the smoothing capacitor 6 fluctuates, so that the output current of the current control unit 7 connected to the subsequent stage is constant. Therefore, the light source 8 cannot be lit stably. Therefore, when the delay time Tdelay is extended, the change amount maximum value Tstep of the delay time Tdelay is provided, and the maintenance time Tk that maintains the delay time Tdelay without change is provided, thereby delaying the time change of the delay time Tdelay. be able to. By performing this control, a sudden change in the switching frequency of the MOSFET 51 can be suppressed.
 このとき、遅延時間Tdelayを維持するための維持時間Tkは、MOSFET51のオン時間をフィードバック制御する応答時間よりも長く設定される。これによりMOSFET51のオン時間が一定値になる時間が確保され、PFC回路5の出力を安定させることができる。 At this time, the maintenance time Tk for maintaining the delay time Tdelay is set longer than the response time for feedback control of the ON time of the MOSFET 51. As a result, a time during which the ON time of the MOSFET 51 is constant is ensured, and the output of the PFC circuit 5 can be stabilized.
 次に図11を用いて、遅延時間をTdelay1からTdelay2に延長する場合の制御に関してより詳細に説明する。図11は遅延時間を延長する場合における制御部の動作を説明するためのフローチャートである。 Next, with reference to FIG. 11, the control when the delay time is extended from Tdelay1 to Tdelay2 will be described in more detail. FIG. 11 is a flowchart for explaining the operation of the control unit when extending the delay time.
 制御部9は、遅延時間Tdelay1を設けて光源8が点灯している状態から、光源8の電流を減少させる方向に調光し(S11)、調光率が閾値1より大きい場合(S12,No)、遅延時間を変更しない(S15)。調光率が閾値1以下の場合(S12,Yes)、制御部9は、遅延時間の最終変更後、遅延時間の維持時間Tkが経過していなければ(S13,No)、遅延時間を変更しない(S15)。制御部9は、遅延時間の最終変更後、遅延時間の維持時間Tkが経過している場合(S13,Yes)、遅延時間がTdelay2以上であれば(S14,No)、遅延時間を変更しない(S15)。遅延時間がTdelay2より小さければ(S14,Yes)、遅延時間をTstep延長する(S16)。 When the light source 8 is turned on with the delay time Tdelay1 provided, the controller 9 performs dimming in the direction of decreasing the current of the light source 8 (S11), and when the dimming rate is greater than the threshold 1 (S12, No ), The delay time is not changed (S15). When the dimming rate is equal to or less than the threshold value 1 (S12, Yes), the control unit 9 does not change the delay time unless the delay time maintenance time Tk has elapsed after the final change of the delay time (S13, No). (S15). If the delay time maintenance time Tk has elapsed after the final change of the delay time (S13, Yes), the control unit 9 does not change the delay time if the delay time is Tdelay2 or more (S14, No) ( S15). If the delay time is smaller than Tdelay2 (S14, Yes), the delay time is extended by Tstep (S16).
 反対に、遅延時間Tdelay2を設けて点灯している状態から光源8の電流を増加する方向に調光し、調光率が閾値1に達した場合、制御部9は、遅延時間をTdelay2からTdelay1に短縮する。 On the other hand, when the light is adjusted in the direction of increasing the current of the light source 8 from the lighting state with the delay time Tdelay2 and the dimming rate reaches the threshold value 1, the control unit 9 changes the delay time from Tdelay2 to Tdelay1. To shorten.
 図12は図9に示す調光率の閾値1を境にして、遅延時間をTdelay2からTdelay1に短縮する場合の、遅延時間、MOSFETのオン時間及び光源の調光率の時間変化を示す図である。遅延時間を急激に短縮すると、MOSFET51のスイッチング周波数が急変し、PFC回路5の出力が変動し、平滑コンデンサ6が電圧変動する影響により、後段に接続される電流制御部7の出力電流が一定値とならず、光源8を安定して点灯することができない。そこで、遅延時間Tdelayを短縮する場合に、遅延時間Tdelayの変化量最大値Tstepを設けると共に、遅延時間Tdelayを変化させずに維持する維持時間Tkを設けることによって、遅延時間Tdelayの時間変化を遅くすることができる。この制御を行うことで、MOSFET51のスイッチング周波数が急変することを抑制できる。 FIG. 12 is a diagram showing temporal changes in delay time, MOSFET on-time, and light source dimming rate when the delay time is shortened from Tdelay2 to Tdelay1 with the threshold value 1 of dimming rate shown in FIG. is there. When the delay time is sharply shortened, the switching frequency of the MOSFET 51 suddenly changes, the output of the PFC circuit 5 fluctuates, and the voltage of the smoothing capacitor 6 fluctuates, so that the output current of the current control unit 7 connected to the subsequent stage is constant Therefore, the light source 8 cannot be lit stably. Therefore, when the delay time Tdelay is shortened, the change amount maximum value Tstep of the delay time Tdelay is provided, and the maintenance time Tk that maintains the delay time Tdelay without change is provided, thereby delaying the time change of the delay time Tdelay. can do. By performing this control, a sudden change in the switching frequency of the MOSFET 51 can be suppressed.
 このとき、遅延時間Tdelayを維持する維持時間Tkは、MOSFET51のオン時間をフィードバック制御する応答時間よりも長く設定される。これによりMOSFET51のオン時間が一定値になる時間が確保され、PFC回路5の出力を安定させることができる。 At this time, the maintenance time Tk for maintaining the delay time Tdelay is set longer than the response time for feedback control of the ON time of the MOSFET 51. As a result, a time during which the ON time of the MOSFET 51 is constant is ensured, and the output of the PFC circuit 5 can be stabilized.
 次に図13を用いて、遅延時間をTdelay2からTdelay1に短縮する場合の制御に関してより詳細に説明する。図13は遅延時間を短縮する場合における制御部の動作を説明するためのフローチャートである。 Next, the control when the delay time is shortened from Tdelay2 to Tdelay1 will be described in detail with reference to FIG. FIG. 13 is a flowchart for explaining the operation of the control unit when the delay time is shortened.
 制御部9は、遅延時間Tdelay2を設けて点灯している状態から、光源8の電流を増加する方向に調光し(S21)、調光率が閾値1以下の場合(S22,No)は、遅延時間を変更しない(S25)。調光率が閾値1より大きい場合(S22,Yes)、遅延時間の最終変更後、遅延時間の維持時間Tkが経過していなければ(S23,No)、遅延時間を変更しない(S25)。制御部9は、遅延時間の最終変更後、遅延時間の維持時間Tkが経過している場合(S23,Yes)、遅延時間がTdelay1以下であれば(S24,No)、遅延時間を変更しない(S25)。遅延時間がTdelay1より大きければ(S24,Yes)、遅延時間をTstep短縮する(S26)。 The control unit 9 performs dimming in the direction of increasing the current of the light source 8 from the lighting state with the delay time Tdelay2 (S21), and when the dimming rate is equal to or less than the threshold 1 (S22, No), The delay time is not changed (S25). If the dimming rate is larger than the threshold value 1 (S22, Yes), the delay time is not changed (S25) if the delay time maintenance time Tk has not passed after the final change of the delay time (S23, No). When the delay time maintaining time Tk has elapsed after the final change of the delay time (S23, Yes), the control unit 9 does not change the delay time if the delay time is equal to or less than Tdelay1 (S24, No) ( S25). If the delay time is larger than Tdelay1 (S24, Yes), the delay time is shortened by Tstep (S26).
 光源8の調光率を変更し、調光率が閾値2、閾値3となる場合に関しても、閾値1の場合と同様の制御が行われる。 When the dimming rate of the light source 8 is changed and the dimming rate becomes the threshold value 2 and the threshold value 3, the same control as in the case of the threshold value 1 is performed.
 なお実施の形態1では光源8がLEDで構成されている場合について説明したが、光源8は調光可能なものであればLEDに限定されず、有機EL(Electro Luminescence)でもよい。 In addition, although the case where the light source 8 was comprised by LED was demonstrated in Embodiment 1, if the light source 8 can be dimmed, it will not be limited to LED, Organic EL (Electro Luminescence) may be sufficient.
実施の形態2.
 図14は実施の形態2に係る点灯装置及び照明器具の構成図である。なお実施の形態2では、図1の実施の形態1に示す点灯装置100及び照明器具200と同一の構成を有する部位には、同一の符号を付してその説明を省略する。
Embodiment 2. FIG.
FIG. 14 is a configuration diagram of a lighting device and a lighting fixture according to the second embodiment. In the second embodiment, parts having the same configurations as those of the lighting device 100 and the lighting fixture 200 shown in the first embodiment of FIG.
 実施の形態2に係る照明器具200Aと、実施の形態1に係る照明器具200との相違点は、照明器具200Aでは、点灯装置100の代わりに点灯装置100Aが用いられていることである。また実施の形態2に係る点灯装置100Aと、実施の形態1に係る点灯装置100との相違点は、点灯装置100Aでは、PFC回路5、平滑コンデンサ6及び電流制御部7の代わりに直流変換回路12が用いられ、さらに制御部9の代わりに制御部9Aが用いられていることである。直流変換回路12は、PFC回路5、平滑コンデンサ6及び電流制御部7の機能を併せ持つ回路である。 The difference between the lighting fixture 200A according to Embodiment 2 and the lighting fixture 200 according to Embodiment 1 is that the lighting fixture 100A is used instead of the lighting device 100 in the lighting fixture 200A. The difference between the lighting device 100A according to the second embodiment and the lighting device 100 according to the first embodiment is that, in the lighting device 100A, a DC conversion circuit is used instead of the PFC circuit 5, the smoothing capacitor 6, and the current control unit 7. 12, and a control unit 9 </ b> A is used instead of the control unit 9. The DC conversion circuit 12 is a circuit having the functions of the PFC circuit 5, the smoothing capacitor 6, and the current control unit 7.
 実施の形態2では、直流変換回路12をフライバック回路で構成した例を説明する。なお直流変換回路12は、フライバック回路の他にも、フライフォワード回路、降圧チョッパ、昇圧チョッパ、昇降圧チョッパ回路、SEPIC、Zetaコンバータ又はCukコンバータといった回路で構成してもよい。 Embodiment 2 describes an example in which the DC conversion circuit 12 is configured by a flyback circuit. In addition to the flyback circuit, the DC conversion circuit 12 may be configured by a circuit such as a fly forward circuit, a step-down chopper, a step-up chopper, a step-up / step-down chopper circuit, a SEPIC, a Zeta converter, or a Cuk converter.
 直流変換回路12は、MOSFET121、トランス122、ダイオード123、平滑コンデンサ124、スナバコンデンサ125、スナバ抵抗126及びスナバダイオード127を備える。 The DC conversion circuit 12 includes a MOSFET 121, a transformer 122, a diode 123, a smoothing capacitor 124, a snubber capacitor 125, a snubber resistor 126, and a snubber diode 127.
 MOSFET121は、負極側直流母線Nにおいて、コンデンサ4とトランス122の1次側との間に配置される。MOSFET121のソースはコンデンサ4の一端と整流回路3とに接続される。MOSFET121のドレインは、スナバダイオード127のアノードとトランス122とに接続される。スナバコンデンサ125、スナバ抵抗126及びスナバダイオード127は、コンデンサ4とトランス122の1次側との間に配置される。 The MOSFET 121 is disposed between the capacitor 4 and the primary side of the transformer 122 in the negative-side DC bus N. The source of the MOSFET 121 is connected to one end of the capacitor 4 and the rectifier circuit 3. The drain of MOSFET 121 is connected to the anode of snubber diode 127 and transformer 122. Snubber capacitor 125, snubber resistor 126 and snubber diode 127 are arranged between capacitor 4 and the primary side of transformer 122.
 スナバ抵抗126の一端は、正極側直流母線Pを介してコンデンサ4の他端と、整流回路3と、スナバコンデンサ125の一端と、トランス122とに接続される。スナバ抵抗126の他端は、スナバコンデンサ125の他端とスナバダイオード127の一端とに接続される。スナバコンデンサ125の他端は、スナバ抵抗126の他端とスナバダイオード127の一端とに接続される。ダイオード123及び平滑コンデンサ124は、トランス122の二次側と光源8との間に配置される。ダイオード123のアノードはトランス122に接続され、ダイオード123のカソードは平滑コンデンサ124の一端と光源8の一端とに接続される。平滑コンデンサ124の他端は、トランス122と光源8の他端とに接続される。 One end of the snubber resistor 126 is connected to the other end of the capacitor 4, the rectifier circuit 3, one end of the snubber capacitor 125, and the transformer 122 via the positive side DC bus P. The other end of the snubber resistor 126 is connected to the other end of the snubber capacitor 125 and one end of the snubber diode 127. The other end of the snubber capacitor 125 is connected to the other end of the snubber resistor 126 and one end of the snubber diode 127. The diode 123 and the smoothing capacitor 124 are disposed between the secondary side of the transformer 122 and the light source 8. The anode of the diode 123 is connected to the transformer 122, and the cathode of the diode 123 is connected to one end of the smoothing capacitor 124 and one end of the light source 8. The other end of the smoothing capacitor 124 is connected to the transformer 122 and the other end of the light source 8.
 不図示のコアに絶縁性ワイヤを巻くことにより、トランス122には、1次巻線122a、2次巻線122b及び3次巻線122cが形成される。 The primary winding 122a, the secondary winding 122b, and the tertiary winding 122c are formed in the transformer 122 by winding an insulating wire around a core (not shown).
 直流変換回路12は、MOSFET121がオンオフ制御されることにより、整流回路3の出力電圧を変換し、光源8に直流電流を出力する。 The direct current conversion circuit 12 converts the output voltage of the rectifier circuit 3 and outputs a direct current to the light source 8 when the MOSFET 121 is on / off controlled.
 制御部9Aは、目標値出力部91、ゼロ電流検出部92、スイッチング制御部93A及び電流入力部94を備える。図1に示す制御部9と図14に示す制御部9Aとの相違点は、制御部9Aでは、電圧検出部95が省かれ、スイッチング制御部93の代わりにスイッチング制御部93Aが用いられていることである。 The control unit 9A includes a target value output unit 91, a zero current detection unit 92, a switching control unit 93A, and a current input unit 94. The difference between the control unit 9 shown in FIG. 1 and the control unit 9A shown in FIG. 14 is that, in the control unit 9A, the voltage detection unit 95 is omitted, and the switching control unit 93A is used instead of the switching control unit 93. That is.
 直流変換回路12の動作を詳細に説明する。 The operation of the DC conversion circuit 12 will be described in detail.
 図15は図14に示す直流変換回路を構成する巻線に流れる電流とMOSFETのドレイン電圧とMOSFETのゲート電圧との関係を示すタイミングチャートである。図15には、上から順に、点灯装置100Aに入力される交流電源1の電流と、1次巻線122aに流れる電流と、3次巻線122cに流れる電流と、MOSFET121のドレイン電圧と、MOSFET121のゲート電圧とが示される。横軸は時間を表す。図15では、点灯装置100Aに入力される交流電源1の電流が「入力電流」として示される。 FIG. 15 is a timing chart showing the relationship between the current flowing through the windings constituting the DC conversion circuit shown in FIG. 14, the drain voltage of the MOSFET, and the gate voltage of the MOSFET. 15, in order from the top, the current of the AC power source 1 input to the lighting device 100A, the current flowing through the primary winding 122a, the current flowing through the tertiary winding 122c, the drain voltage of the MOSFET 121, and the MOSFET 121 The gate voltage is shown. The horizontal axis represents time. In FIG. 15, the current of the AC power supply 1 input to the lighting device 100 </ b> A is indicated as “input current”.
 図15では、説明の便宜上、MOSFET121のゲート電圧がオンオフされる周期を、実際よりも長く記載している。MOSFET121のゲート電圧がオンオフされる周期は、MOSFET121のゲート電圧がオフからオンに変化した時点から、再びMOSFET121のゲート電圧がオフからオンに変化するまでの時間に等しい。 In FIG. 15, for convenience of explanation, the cycle in which the gate voltage of the MOSFET 121 is turned on / off is shown to be longer than the actual period. The period during which the gate voltage of the MOSFET 121 is turned on / off is equal to the time from when the gate voltage of the MOSFET 121 changes from off to on until when the gate voltage of the MOSFET 121 changes from off to on again.
 MOSFET121がオンされたとき、交流電源1、整流回路3、1次巻線122a及びMOSFET121により閉回路が形成され、交流電源1が1次巻線122aを介して短絡される。そのため閉回路に電源電流が流れ、1次巻線122aに流れる電流が増加し、1次巻線122aにエネルギーが蓄積される。 When the MOSFET 121 is turned on, a closed circuit is formed by the AC power source 1, the rectifier circuit 3, the primary winding 122a, and the MOSFET 121, and the AC power source 1 is short-circuited through the primary winding 122a. As a result, the power source current flows through the closed circuit, the current flowing through the primary winding 122a increases, and energy is stored in the primary winding 122a.
 スイッチング制御部93Aに設定されたオン時間が経過すると、MOSFET121がオフされることにより、3次巻線122c、ダイオード123及び平滑コンデンサ124の閉回路が形成される。この閉回路において1次巻線122aに蓄えられたエネルギーが放出され、平滑コンデンサ124が充電される。 When the ON time set in the switching control unit 93A elapses, the MOSFET 121 is turned off to form a closed circuit of the tertiary winding 122c, the diode 123, and the smoothing capacitor 124. In this closed circuit, the energy stored in the primary winding 122a is released, and the smoothing capacitor 124 is charged.
 3次巻線122cに流れる電流がゼロになった時点から遅延時間Tdelayが経過するまで、MOSFET121のオフ状態は維持され、遅延時間Tdelayが経過したときにMOSFET121は再びオン状態になる。 The MOSFET 121 is kept off until the delay time Tdelay elapses after the current flowing through the tertiary winding 122c becomes zero, and the MOSFET 121 is turned on again when the delay time Tdelay elapses.
 MOSFET121の一連のオンオフ動作により、1次巻線122aに流れる電流は、三角波状の波形となり、その頂点が点線で示すような正弦波の包絡線になる。 Due to a series of on / off operations of the MOSFET 121, the current flowing through the primary winding 122a has a triangular waveform, and a sine wave envelope whose apex is indicated by a dotted line.
 このとき、交流電源1から入力される電流は、入力フィルタ2により平滑化され、コイル21に流れるコイル電流の平均値が入力され、正弦波状の電流波形となる。 At this time, the current input from the AC power source 1 is smoothed by the input filter 2, and the average value of the coil current flowing through the coil 21 is input to form a sine wave current waveform.
 制御部9Aが光源8に流れる電流を検出して、検出された電流が目標値に追従するようフィードバック制御されることで、MOSFET121のオン時間が制御される。 The control unit 9A detects the current flowing through the light source 8, and feedback control is performed so that the detected current follows the target value, whereby the on-time of the MOSFET 121 is controlled.
 MOSFET121のオン時間をフィードバック制御する際、オン時間が大きく変化してしまうと、1次巻線122aに流れる電流の頂点の包絡線が正弦波にならず、交流電源1の入力電流を正弦波状にすることができない。そのため制御部9Aでは、フィードバック制御の応答時間が、フィードバック制御のループゲインを交流電源1の1周期の1/2周期以上で1倍(0dB)以下となるように、設定される。言い換えると、フィードバック制御の応答時間は、交流電源1の周波数の2倍以下の周波数で1倍(0dB)以下となるように設定される。 When the on-time of the MOSFET 121 is feedback-controlled, if the on-time greatly changes, the envelope of the peak of the current flowing through the primary winding 122a does not become a sine wave, and the input current of the AC power supply 1 becomes a sine wave. Can not do it. Therefore, in the control unit 9A, the response time of the feedback control is set so that the loop gain of the feedback control is not less than 1/2 of one cycle of the AC power supply 1 and not more than 1 (0 dB). In other words, the response time of the feedback control is set to be 1 (0 dB) or less at a frequency that is 2 times or less of the frequency of the AC power supply 1.
 具体的に説明すると、電源周波数が50Hzの場合、電源周波数の半周期(半波)の周波数100Hz以下、すなわち周期10msec以上で、定電流フィードバック制御のループゲインを1倍(0dB)以下とすることにより、定電流フィードバック制御は電源周期の1/2より短い周期で応答しないように設定される。これにより電源周期の1/2周期以内においては、MOSFET121のオン時間の変動が抑制され、1次巻線122aに流れる電流の頂点の包絡線が正弦波状の波形となる。 More specifically, when the power supply frequency is 50 Hz, the loop gain of the constant current feedback control is set to be 1 (0 dB) or less at a frequency of 100 Hz or less of a half cycle (half wave) of the power supply frequency, that is, a cycle of 10 msec or more. Thus, the constant current feedback control is set so as not to respond in a cycle shorter than ½ of the power cycle. As a result, the fluctuation of the on-time of the MOSFET 121 is suppressed within a half cycle of the power supply cycle, and the envelope of the peak of the current flowing through the primary winding 122a becomes a sine wave waveform.
 またフィードバック制御において、オン時間の更新周期を、交流電源1の周期の半分に相当する周期、又は交流電源1の周期の半分に相当する周期よりも長い周期とすることによっても、同様の効果を得ることができる。 In the feedback control, the same effect can be obtained by setting the on-time update cycle to a cycle corresponding to half the cycle of the AC power supply 1 or a cycle longer than the cycle corresponding to half the cycle of the AC power supply 1. Obtainable.
 実施の形態2に係る点灯装置100A及び照明器具200Aは、実施の形態1と同様に遅延時間Tdelayを設けて、電流不連続モード制御によりMOSFET121をスイッチング制御することで、電流臨界モード制御する場合に比べて、スイッチング周波数を低くすることができるため、MOSFET121で発生するスイッチング損失を低減できる。 The lighting device 100A and the lighting fixture 200A according to the second embodiment are provided with the delay time Tdelay as in the first embodiment, and when the current critical mode control is performed by switching the MOSFET 121 by the current discontinuous mode control. In comparison, since the switching frequency can be lowered, the switching loss generated in the MOSFET 121 can be reduced.
 なお実施の形態1,2では調光率に応じて遅延時間の長さを変える例を説明したが、遅延時間の長さは、調光率の代わりに直流変換回路30がLEDに出力する出力電流目標値により判定してもよい。またこの場合、直流変換回路の出力の大きさは、LEDの調光率により判定されたものでもよいし、LEDの出力電流目標値により判定されたものでもよいし、有機ELの調光率により判定されたものでもよい。また直流変換回路の出力の大きさは、LEDの出力電流目標値より判定されるものでもよい。また実施の形態1,2に係る制御部は、調光率の代わりに、出力電流目標値に応じて遅延時間の長さを変えるように構成してもよい。 In the first and second embodiments, the example in which the length of the delay time is changed according to the dimming rate has been described. However, the length of the delay time is an output that the DC conversion circuit 30 outputs to the LED instead of the dimming rate. The determination may be made based on the current target value. In this case, the magnitude of the output of the DC conversion circuit may be determined by the dimming rate of the LED, may be determined by the output current target value of the LED, or may be determined by the dimming rate of the organic EL. It may be determined. The magnitude of the output of the DC conversion circuit may be determined from the output current target value of the LED. Moreover, you may comprise the control part which concerns on Embodiment 1, 2 so that the length of delay time may be changed according to an output current target value instead of a light control rate.
 以上の実施の形態に示した構成は、本発明の内容の一例を示すものであり、別の公知の技術と組み合わせることも可能であるし、本発明の要旨を逸脱しない範囲で、構成の一部を省略、変更することも可能である。 The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.
 1 交流電源、2 入力フィルタ、3 整流回路、4,22,74 コンデンサ、5 PFC回路、6,124 平滑コンデンサ、7 電流制御部、8 光源、9,9A 制御部、10 調光器、11 電流検出部、12,30 直流変換回路、21,52,72 コイル、51,71,121 MOSFET、52a,122a 1次巻線、52b,122b 2次巻線、53,73,123 ダイオード、91 目標値出力部、92 ゼロ電流検出部、93,93A スイッチング制御部、94 電流入力部、95 電圧検出部、100,100A 点灯装置、122 トランス、122c 3次巻線、125 スナバコンデンサ、126 スナバ抵抗、127 スナバダイオード、200,200A 照明器具。 1 AC power supply, 2 input filter, 3 rectifier circuit, 4,22,74 capacitor, 5 PFC circuit, 6,124 smoothing capacitor, 7 current control unit, 8 light source, 9, 9A control unit, 10 dimmer, 11 current Detection unit, 12, 30 DC conversion circuit, 21, 52, 72 coil, 51, 71, 121 MOSFET, 52a, 122a primary winding, 52b, 122b secondary winding, 53, 73, 123 diode, 91 target value Output unit, 92 zero current detection unit, 93, 93A switching control unit, 94 current input unit, 95 voltage detection unit, 100, 100A lighting device, 122 transformer, 122c tertiary winding, 125 snubber capacitor, 126 snubber resistance, 127 Snubber diode, 200, 200A lighting fixture.

Claims (13)

  1.  交流電力を整流する整流回路と、
     高調波を抑制して力率を改善すると共に前記整流回路から出力される電力を直流電力に変換して光源に供給する直流変換回路と、
     直流変換回路を制御する制御部と
     を備え、
     前記直流変換回路は、平滑コンデンサと、前記平滑コンデンサ及び前記整流回路の間に配置されるスイッチング素子と、前記整流回路から出力される電流が流れるコイルとを有し、
     前記制御部は、前記コイルに流れる電流がゼロになった時点から、前記制御部に設定された遅延時間が経過するまで前記スイッチング素子をオフ状態にさせて、前記遅延時間が経過したときに前記スイッチング素子をオンさせる点灯装置。
    A rectifier circuit for rectifying AC power;
    A DC conversion circuit that suppresses higher harmonics to improve the power factor and converts the power output from the rectifier circuit to DC power and supplies it to the light source;
    A control unit for controlling the DC conversion circuit,
    The DC conversion circuit includes a smoothing capacitor, a switching element disposed between the smoothing capacitor and the rectifier circuit, and a coil through which a current output from the rectifier circuit flows.
    The control unit turns off the switching element until the delay time set in the control unit elapses from when the current flowing through the coil becomes zero, and when the delay time elapses, A lighting device that turns on a switching element.
  2.  前記制御部は、前記直流変換回路の出力の大きさに応じて前記遅延時間の長さを変える請求項1に記載の点灯装置。 The lighting device according to claim 1, wherein the control unit changes a length of the delay time according to a magnitude of an output of the DC conversion circuit.
  3.  前記制御部は、前記出力の大きさに閾値を設けて、前記出力が前記閾値を上回る場合には前記遅延時間を一定の長さとし、前記出力が前記閾値以下である場合には、前記出力が低下するほど前記遅延時間を長くする請求項2に記載の点灯装置。 The control unit sets a threshold for the magnitude of the output, sets the delay time to a certain length when the output exceeds the threshold, and outputs the output when the output is less than or equal to the threshold. The lighting device according to claim 2, wherein the delay time is lengthened as it decreases.
  4.  前記制御部は、前記出力の大きさに複数の閾値を設けて、隣接する閾値同士の間の範囲に応じて互いに異なる長さの複数の前記遅延時間を用いて前記スイッチング素子を制御する請求項2に記載の点灯装置。 The said control part provides a some threshold value in the magnitude | size of the said output, and controls the said switching element using the said some delay time of mutually different length according to the range between adjacent threshold values. 2. The lighting device according to 2.
  5.  前記制御部は、前記スイッチング素子をオフしている期間において、前記スイッチング素子の電圧振動が2回目以降のボトムとなるタイミングで前記スイッチング素子をオンさせる請求項1から4の何れか一項に記載の点灯装置。 5. The control unit according to claim 1, wherein the control unit turns on the switching element at a timing when the voltage oscillation of the switching element becomes a bottom after the second time in a period in which the switching element is turned off. Lighting device.
  6.  前記制御部は、前記スイッチング素子の最小オン時間を設けて、前記出力の大きさに応じて前記遅延時間の長さを変えることにより、前記最小オン時間以上のオン時間で前記スイッチング素子を動作させる請求項2から5の何れか一項に記載の点灯装置。 The control unit operates the switching element with an on-time that is equal to or greater than the minimum on-time by providing a minimum on-time of the switching element and changing the length of the delay time according to the magnitude of the output. The lighting device according to any one of claims 2 to 5.
  7.  前記制御部は、予め設定された維持時間において前記遅延時間の変化量最大値を設けて前記遅延時間の長さを変える請求項2から6の何れか一項に記載の点灯装置。 The lighting device according to any one of claims 2 to 6, wherein the control unit changes the length of the delay time by providing a maximum change amount of the delay time in a preset maintenance time.
  8.  前記光源はLEDで構成される請求項1から7の何れか一項に記載の点灯装置。 The lighting device according to any one of claims 1 to 7, wherein the light source is configured by an LED.
  9.  前記出力の大きさは、前記LEDの調光率により判定される請求項8に記載の点灯装置。 The lighting device according to claim 8, wherein the magnitude of the output is determined by a dimming rate of the LED.
  10.  前記出力の大きさは、前記LEDの出力電流目標値により判定される請求項8に記載の点灯装置。 The lighting device according to claim 8, wherein the magnitude of the output is determined by an output current target value of the LED.
  11.  前記光源は有機ELで構成される請求項1から7の何れか一項に記載の点灯装置。 The lighting device according to any one of claims 1 to 7, wherein the light source is configured by an organic EL.
  12.  前記出力の大きさは、前記有機ELの調光率により判定される請求項11に記載の点灯装置。 The lighting device according to claim 11, wherein the magnitude of the output is determined by a dimming rate of the organic EL.
  13.  請求項1から12の何れか一項に記載の点灯装置を備えた照明器具。 A lighting fixture comprising the lighting device according to any one of claims 1 to 12.
PCT/JP2016/089196 2016-12-28 2016-12-28 Lighting device and illumination apparatus WO2018123056A1 (en)

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