JP2015216102A - Lighting device and lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of suppressing a decrease in a power factor and an increase in harmonic current, and a lighting fixture.SOLUTION: A lighting device 100 comprises a rectification circuit 2, a converter unit 3 which is a conversion circuit, an output current detection resistor R3 which is a current detection unit, and a control circuit 4. The rectification circuit 2 converts an AC voltage to a DC voltage. The converter unit 3 is connected between DC output terminals of the rectification circuit 2, includes an output smoothing capacitor C3 between load output terminals, and supplies a DC current to the LED 5 connected in parallel to the output smoothing capacitor C3. A selection circuit 132 selects any of a power path from a DC output of the rectification circuit 2 to a control power supply circuit 30 and a power path from the output smoothing capacitor C3 to the control power supply circuit 30, and supplies power to the control power supply circuit 30.

Description

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

  Conventionally, a lighting device for lighting a light emitting element such as a light emitting diode (LED) is known. This type of lighting device includes an AC-DC conversion circuit unit that rectifies and smoothes a commercial AC power supply to generate a DC voltage, and a DC-DC converter unit that supplies an optimal current to the LED from the obtained DC voltage. For example, a capacitor input type rectifier circuit is used as the AC-DC conversion circuit unit, and a buck converter is used as the DC-DC converter unit.

  Many lighting fixtures are currently required to have a high power factor, so the capacitor input type rectifier circuit has a poor power factor and cannot meet the high power factor requirement. Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-40400, one using a step-up chopper type power factor correction circuit as an AC-DC converter is currently widely used. In this case, two converters, a step-up chopper and a buck converter, are required. For example, as disclosed in Japanese Patent Application Laid-Open No. 2011-62043, a method of performing power factor improvement and LED current control with a single converter using a flyback converter has been developed.

  However, the two-converter system that combines a power factor correction circuit and a buck converter has a problem of increasing the size and cost of the circuit board because the number of parts increases. Further, a flyback converter that performs power factor correction circuit and LED current control with one converter has a merit that the number of components is small and the circuit board can be downsized. However, since the power is changed via the transformer, there is a problem that the loss of the transformer is large and the power conversion efficiency is deteriorated as the whole lighting device.

  On the other hand, Japanese Patent Application Laid-Open No. 2011-82204 discloses a lighting circuit using a SEPIC (Single Ended Primary Inductor Converter) circuit. A SEPIC circuit is a simple circuit that requires only one converter and has an advantage of high power conversion efficiency because a transformer is not required for power conversion.

JP 2010-40400 A JP 2011-62043 A JP 2011-82204 A

  In a lighting device that performs power factor correction control and constant current control, it is required to suppress power factor reduction and harmonic current increase.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a lighting device and a lighting fixture that can suppress a power factor decrease and a harmonic current increase.

  A lighting device according to the present invention is connected between a rectifier circuit that converts an AC voltage into a DC voltage, and a DC output terminal of the rectifier circuit, has an output smoothing capacitor between load output terminals, and supplies a DC current to a light source. And a control circuit that drives and controls the conversion circuit. The control circuit operates by receiving power for driving the control circuit from a control power supply circuit and supplies a direct current to the light source. While being performed, the control power supply circuit receives power from the output smoothing capacitor at least in the vicinity of the zero cross of the AC voltage to generate driving power for the control circuit, and from the DC output of the rectifier circuit, Either a power path leading to the control power circuit or a power path leading from the output smoothing capacitor to the control power circuit is selected to supply power to the control power circuit. Further comprising a selection circuit for performing.

  A lighting fixture according to the present invention includes a light source including a light emitting element, and a lighting device that lights the light source. The lighting device includes a rectifier circuit that converts an AC voltage into a DC voltage, and a DC output of the rectifier circuit. A conversion circuit connected between the terminals and having an output smoothing capacitor between the load output terminals and supplying a direct current to the light source; and a control circuit for driving and controlling the conversion circuit, the control circuit comprising a control power supply The control power supply circuit operates while receiving the supply of driving power for the control circuit from the circuit, and while the direct current is supplied to the light source, the control power supply circuit supplies power from the output smoothing capacitor at least near the zero cross of the alternating voltage. The power supply is generated to generate driving power for the control circuit, and the power path from the DC output of the rectifier circuit to the control power supply circuit, and the control from the output smoothing capacitor Source further comprises a power path to the circuit, a selection circuit for supplying power to the control power circuit by selecting one of the paths of the.

  According to the present invention, since a path capable of supplying power from both the DC side of the rectifier circuit and the output smoothing capacitor is provided, when the voltage on the DC side of the rectifier circuit is lower than the output smoothing capacitor, control is performed from the output smoothing capacitor. Power for generating power can be supplied to the control power circuit. Thereby, the current flowing into the control power supply circuit from the DC side of the rectifier circuit can be reduced, and the power factor reduction and the harmonic current increase can be suppressed.

It is a circuit block diagram which shows an example of the lighting device which can apply this invention. It is a wave form diagram which shows operation | movement of the lighting device which can apply this invention. It is a wave form diagram which shows the power factor improvement operation | movement of the lighting device which can apply this invention. It is a circuit block diagram of the phase compensation circuit with which the lighting device which can apply this invention is provided. It is a circuit block diagram of the lighting device concerning the comparative example with respect to the lighting device which can apply this invention. It is a circuit block diagram of the modification of the lighting device which can apply this invention. It is a circuit block diagram of the lighting device concerning Embodiment 1 of this invention. It is a wave form diagram which shows operation | movement of the lighting device concerning Embodiment 1 of this invention. It is a circuit block diagram of the lighting device concerning the modification of Embodiment 1 of this invention. It is a circuit block diagram of the lighting device concerning the modification of Embodiment 1 of this invention. It is a circuit block diagram of the lighting device concerning the modification of Embodiment 1 of this invention. It is sectional drawing of the lighting fixture concerning Embodiment 2 of this invention.

An example of a lighting device to which the present invention is applicable.
FIG. 1 is a circuit configuration diagram of a lighting device 100 which is an example of a lighting device to which the present invention can be applied. The lighting device 100 is supplied with electric power from the AC power source 1 and turns on the light source. The lighting device 100 includes a rectifier circuit 2, a converter unit 3, and a control circuit 4. The rectifier circuit 2 performs full-wave rectification on the AC voltage input from the AC power supply 1 and converts it to a DC voltage. This DC voltage is not smoothed during the operation of the converter unit 3 and becomes a ripple voltage including twice the frequency of the AC power supply 1.

  As an example of the light source, an LED (Light Emitting Diode) 5 shown in FIG. 1 is used.

  The converter unit 3 includes a filter capacitor C1, a first inductor L1, a switching element SW1 (for example, a MOSFET), a coupling capacitor C2, a second inductor L2, a diode D1, and an output smoothing capacitor C3. The converter unit 3 includes a SEPIC (that is, Single Ended Primary Inductor Converter) circuit constituted by these circuit elements. An LED 5 that is a light source is connected to the output of the converter unit 3.

  Specifically, the first inductor L1 includes a primary winding L1a and a secondary winding L1b that is magnetically coupled to the primary winding L1a. One end of the primary winding L1a of the first inductor L1 is connected to one end of the filter capacitor C1. The other end of the filter capacitor C1 is connected to the reference potential GND.

  The switching element SW1 includes a drain terminal, a source terminal, and a gate terminal that switches between these terminals. The switching element SW1 has a drain terminal connected to the other end of the primary winding L1a of the first inductor L1, and is connected in parallel to the filter capacitor C1 via the first inductor L1.

  One end of the coupling capacitor C2 is connected to the drain terminal of the switching element SW1. One end of the second inductor L2 is connected to the other end of the coupling capacitor C2. The other end of the second inductor L2 is connected to the reference potential GND. The second inductor L2 is connected in parallel with the switching element SW1 via the coupling capacitor C2. The first inductor L1 and the second inductor L2 may be wound around individual cores (magnetic cores), or both the first inductor L1 and the second inductor L2 may be wound around one core, The core may be shared.

  The anode of the diode D1 is connected between one end of the second inductor L2 and the other end of the coupling capacitor C2. One end of the output smoothing capacitor C3 is connected to the cathode of the diode D1. The other end of the output smoothing capacitor C3 is connected to one end of the output current detection resistor R3. The other end of the output current detection resistor R3 is connected to the reference potential GND. An LED 5 is connected in parallel to the output smoothing capacitor C3.

  The converter unit 3 operates under the control of the control circuit 4. The converter unit 3 converts the DC voltage that has been full-wave rectified by the rectifier circuit 2 into a current and voltage suitable for lighting the LED 5. The converter unit 3 operates so that the input current waveform is sinusoidal and in phase with the AC input voltage under the control of the control circuit 4 to improve the power factor.

  The control circuit 4 includes an error amplifier 9 including an operational amplifier 6, a capacitor 7, and a resistor 8, a first comparator 10, a flip-flop circuit 11, a signal generator 12, a second comparator 13, and a drive circuit 14. The control circuit 4 drives the switching element SW1 so that the AC input current waveform of the lighting device 100 is substantially in phase with the AC input voltage and is a sine wave while the current flowing through the LED 5 has a predetermined current value. .

  The output current detection resistor R3 is for detecting the current flowing through the LED 5, but is not connected to a position where the current of the LED 5 is directly detected, but is connected to a position where the charging current to the output smoothing capacitor C3 can be detected. Has been. Since the current flowing through the LED 5, that is, the average value of the discharge current of the output smoothing capacitor C3 is equal to the average value of the charging current to the output smoothing capacitor C3, if the discharge current of the output smoothing capacitor C3 is known, the current flowing through the LED can be obtained. it can.

  The error amplifier 9 compares the voltage signal generated in the output current detection resistor R3 with the capacitor 7 and the resistor 8 and compares it with the first reference voltage E1, and outputs a signal corresponding to the difference between the two. If the voltage generated in the output current detection resistor R3 is higher than the first reference voltage E1, the output voltage of the error amplifier 9 decreases. If the voltage generated in the output current detection resistor R3 is lower than the first reference voltage E1, The output voltage of the error amplifier 9 increases. The capacitor 7 and the resistor 8 constitute a phase compensation circuit that determines the response time of feedback control. The larger the capacitance of the capacitor 7 and the larger the resistance value of the resistor 8, the longer the response time of feedback control. The smaller the capacitance of the capacitor 7 and the smaller the resistance value of the resistor 8, the shorter the response time of feedback control.

  The second reference voltage E2 is input to the input of the first comparator 10, and the secondary winding L1b is connected to the other input. Secondary winding L1b is magnetically coupled to primary winding L1a. When the voltage generated in the secondary winding L1b is higher than the voltage of the second reference voltage E2, the first comparator 10 outputs a high signal (for example, 5V). When the voltage generated in the secondary winding L1b is lower than the voltage of the second reference voltage E2, the first comparator 10 outputs a low signal (for example, 0V).

  The flip-flop circuit 11 includes a reset input terminal R, a set input terminal S, and an output terminal Q. The signal generator 12 has a terminal for outputting a sawtooth triangular wave and a terminal for outputting a set signal to the set input terminal S of the flip-flop circuit 11 in accordance with the signal of the output terminal of the first comparator.

  The second comparator 13 compares the triangular wave output from the signal generator 12 with the signal output from the error amplifier 9, and outputs a reset signal to the reset input terminal of the flip-flop circuit according to the comparison result. The drive circuit 14 converts and outputs a signal suitable for driving the switching element SW1 based on the signal of the output terminal Q of the flip-flop circuit 11, and drives the switching element SW1.

  The configuration of the control circuit 4 is an example and is not limited to this configuration. A combination of a digital circuit and an analog circuit may be used as in this configuration, or software control may be performed by combining an A / D converter and a microcomputer. Further, a control power supply circuit for driving the control circuit 4 is necessary, but is not shown here. For example, if the control power supply circuit is provided with an auxiliary winding for supplying control power to the first inductor L1 or the second inductor L2, the control power supply can be obtained therefrom. Alternatively, a separate switching power supply may be provided and supplied from there.

  Next, the operation of the lighting device 100 will be described.

  When the AC power supply 1 is applied to the lighting device 100, the rectifier circuit 2 performs full-wave rectification on the AC voltage to generate a DC voltage. The filter capacitor C1 is provided for the purpose of removing the switching ripple, and is not for smoothing the power supply frequency component of the full-wave rectified waveform here. Therefore, during the operation of the converter unit 3, a full-wave rectified waveform pulsating in a sine wave shape at a frequency twice the power supply frequency is applied to the converter unit 3.

  The operation of the converter unit 3 in the steady state will be described. When the switching element SW1 is turned on, the AC power supply 1 is short-circuited via the first inductor L1, so that current is supplied from the power input side in the order of the first inductor L1 and the switching element SW1, and energy is stored in the first inductor L1. It is done. At this time, the current of the first inductor L1 increases.

  At the same time, the voltage stored in the coupling capacitor C2 is applied to the second inductor L2. For this reason, a current flows in the order of the coupling capacitor C2, the switching element SW1, and the second inductor L2, and the energy of the coupling capacitor C2 is stored in the second inductor L2. At this time, the current of the second inductor L2 increases.

  Next, when the switching element SW1 is turned off, the energy stored in the first inductor L1 is released, and a current flows in the order of the first inductor L1, the coupling capacitor C2, the diode D1, and the output smoothing capacitor C3. Thereby, the coupling capacitor C2 and the output smoothing capacitor C3 can be charged.

  At the same time, the energy stored in the second inductor L2 is released, and a current flows in the order of the second inductor L2, the diode D1, and the output smoothing capacitor C3. Thereby, the output smoothing capacitor C3 can be charged. In this way, energy is transmitted to the load side, and finally a smoothed direct current is supplied from the output smoothing capacitor C3 to the LED 5, and the LED 5 emits light.

  The SEPIC circuit can perform any operation of an input voltage, that is, a step-up operation that outputs a voltage higher than the DC side voltage of the rectifier circuit 2 and a step-down operation that outputs a voltage lower than the input voltage. A conversion circuit capable of only one of the operations may be mounted on the lighting device 100.

  Next, the operation of the control circuit 4 will be described with reference to the waveform diagram of FIG. FIG. 2 is a waveform diagram showing the operation of the lighting device 100.

(Period t0 to t1)
Here, the operation of the converter unit 3 is in a steady state and the switching element SW1 is turned on by the control circuit 4 will be described. When the switching element SW1 is turned on, a total current of the current flowing through the primary winding L1a of the first inductor L1 and the current flowing through the second inductor L2 flows through the switching element SW1.

  Since the current flowing through the first inductor L1 and the current flowing through the second inductor L2 both increase, the current flowing through the switching element SW1 also increases. At this time, the voltage VL1a is applied to the primary winding L1a of the first inductor L1 in the direction of the arrow in FIG. 1, and the voltage VL1b is generated in the direction of the arrow to the secondary winding of the first inductor L1. The input side of one comparator 10 is a negative voltage. Accordingly, since the voltage is lower than the second reference voltage E2 of the first comparator 10, the output of the first comparator 10 is in a state where a low signal is output.

  The second comparator 13 compares the triangular wave output from the signal generator 12 with the output signal of the error amplifier 9. Here, the output voltage of the error amplifier 9 is higher than that of the signal generator 12 (triangular wave), and a low signal is output from the output of the second comparator 13.

(Time t1)
When the triangular wave voltage of the signal generator 12 rises and becomes higher than the output voltage of the error amplifier 9, the second comparator 13 outputs a high signal. Therefore, a high signal is input to the reset input terminal R of the flip-flop circuit 11. Then, the flip-flop circuit 11 receives this and outputs a low signal to the output (Q). As a result, an OFF signal is input to the gate of the switching element SW1, the switching element is turned off, and the current of the switching element SW1 is cut off.

(Period t1-t2)
When the switching element SW1 is turned off, the energy stored in the first inductor L1 is released to the output smoothing capacitor C3 via the coupling capacitor C2 and the diode D1. At the same time, the energy stored in the second inductor L2 is also released to the output smoothing capacitor C3 via the diode D1.

  At this time, the voltage generated in the primary winding L1a of the first inductor L1 is a voltage opposite to that when the switching element is on. That is, the arrow in FIG. 1 is a reverse voltage. Thereby, the voltage generated in the secondary winding of the first inductor L1 also becomes a voltage in the direction opposite to the arrow in FIG.

  That is, a positive voltage is input to the non-inverting input terminal of the first comparator 10. At this time, since the generated voltage of the secondary winding L1b of the first inductor L1 is higher than the second reference voltage E2 of the first comparator 10, a high signal is output from the output of the first comparator 10. , Input to the signal generator 12.

(Period t2-t3)
Since the first inductor L1 and the second inductor L2 release energy, the current flowing to the load side via the diode D1 decreases, and the current of the diode D1 becomes zero. Then, the voltage VL1b of the secondary winding L1b of the first inductor L1 rapidly decreases.

(Time t3)
When the generated voltage VL1b of the secondary winding L1b of the first inductor L1 becomes lower than the second reference voltage E2 connected to the first comparator 10, the first comparator 10 outputs a low signal to the signal generator 12. Output. In response to this, the signal generator 12 outputs a high signal to the set input terminal S of the flip-flop circuit 11. As a result, a high signal is output from the output terminal Q of the flip-flop circuit 11. In response to this, the drive circuit 14 inputs an ON signal to the gate of the switching element SW1 to make the switching element SW1 conductive. Then, the next switching cycle is started.

  Here, the power factor improving operation and the constant current control will be described. FIG. 3 is a waveform diagram showing the power factor improving operation of the lighting device 100.

When the switching element SW1 is turned on, the current flowing through the primary winding L1a of the first inductor L1 rises almost linearly. The current value IL is IL = Et / L1a
It is represented by Here, E represents the instantaneous value of the full-wave rectified voltage, L1a represents the inductance of the primary winding L1a of the first inductor L1, and t represents the elapsed time since the switching element SW1 was turned on. This shows that the current flowing through the primary winding L1a of the first inductor L1 is proportional to the full-wave rectified voltage and inversely proportional to the inductance L1.

  Here, assuming that the on-time t (ON) of the switching element is fixed and it is a full-wave rectified waveform, when the AC power supply is operated for a half cycle, the inductance L1a is fixed. Therefore, as shown in FIG. The current peak value has a waveform proportional to the power supply voltage. By removing the switching ripple from the current flowing through the first inductor L1 by the filter capacitor C1 and averaging it, the input current flowing from the AC power supply 1 can be made close to a sine wave shape and can be substantially in phase with the AC power supply voltage. The rate can be improved and the harmonics can be reduced. Although not shown in FIG. 1, a filter circuit may be further added to the AC input side of the rectifier circuit 2 as necessary.

  Thus, if the on-time t (ON) of the switching element SW1 is fixed for a half period of the power source, the power factor can be improved and the harmonics can be reduced. On the other hand, in order to obtain the necessary brightness, constant current feedback control is required in which the current supplied to the LED 5 is constantly monitored and the on-time of the switching element SW1 is adjusted so that the target current value flows. That is, if the current value actually flowing to the LED 5 is smaller than the target current value, the on-time of the switching element SW1 is lengthened to increase the LED current. If the current value actually flowing to the LED 5 is larger than the target current value, the on-time of the switching element SW1 is shortened to decrease the LED current. Since the forward voltage of the LED 5 generally exhibits a characteristic close to a constant voltage, in order to stably light the LED 5 at a predetermined brightness, constant current feedback is performed so that the output current becomes a desired current value in this way. It is necessary to control the switching element SW1 by control.

  However, as described above, when the on-time of the switching element SW1 fluctuates greatly due to the constant current feedback control within the half cycle of the AC power supply, the peak value of the current flowing through the primary winding L1a of the first inductor L1 is sinusoidal. Otherwise, the power factor may decrease and the harmonic current of the input current may increase.

  Therefore, the response time of the constant current feedback control is set so that the loop gain of the feedback control is equal to or more than ½ period of one period of the AC power supply 1 and equal to or less than 1 (0 dB). In other words, the frequency is set to be 1 (0 dB) or less at a frequency 2 times or less of the frequency of the AC power supply 1. For example, when the power supply frequency is 50 Hz, the constant current feedback control is set to the power supply cycle by setting the loop gain of the constant current feedback control to 1 (0 dB) or less at 100 Hz or less corresponding to the half cycle (half wave), that is, the cycle of 10 ms or more. It sets so that it may not respond with a period shorter than 1/2. As a result, the fluctuation of the ON time of the switching element is suppressed within a half cycle of the power supply cycle, and the current peak value of the primary winding L1a of the first inductor L1 has a waveform proportional to the power supply voltage. The loop gain can be set by a constant of a phase compensation circuit including a capacitor 7 and a resistor 8. The phase compensation circuit is not limited to this configuration. For example, a resistor 16 and a capacitor 15 may be added in parallel with the capacitor 7 as shown in FIG. In the modification shown in FIG. 4, one end of the series circuit of the capacitor 15 and the resistor 16 is connected to a connection point between one end of the capacitor 7 and the output terminal of the operational amplifier 6, and the other end of the series circuit is connected to the other end of the capacitor 7 and the resistor. It is connected to 8 connection points.

  Next, the operation of constant current feedback control will be described. In the error amplifier 9, if the voltage generated by the output current detection resistor R3 is higher than the first reference voltage E1, the output of the operational amplifier 6 decreases with time, and the output current detection resistor R3 is lower than the first reference voltage E1. If the generated voltage is lower, the output voltage of the operational amplifier 6 operates so as to increase with the passage of time and functions as an integration circuit.

  When the output voltage of the operational amplifier 6 decreases, the on-time of the switching element SW1 decreases and the LED current decreases. When the output voltage of the operational amplifier 6 increases, the on-time of the switching element SW1 increases, and the LED current decreases. It becomes control of the direction to increase.

  For example, it is assumed that the signal detected by the output current detection resistor R3 is smaller than the voltage of the first reference voltage E1 of the error amplifier 9. At this time, the voltage of the output signal of the error amplifier 9 constituting the integration circuit increases with time. Therefore, the voltage input to the inverting input terminal of the second comparator 13 increases. The non-inverted input terminal of the second comparator 13 receives a triangular wave signal output from the signal generator 12, and the second signal is output when the triangular wave signal level exceeds the signal level of the inverted input terminal, that is, the output signal level of the error amplifier. A high signal is output from the comparator 13 and input to the reset input terminal R of the flip-flop circuit. When a high signal is input to the reset input terminal R, the output terminal Q of the flip-flop circuit 11 becomes a low signal, and the switching element is turned off.

  By the way, in the lighting device 100, the output current detection resistor R3 for detecting the current flowing through the LED is not connected in series with the LED 5, but is connected to a position for detecting the charging current to the output smoothing capacitor C3.

  Furthermore, in order to improve the power factor and reduce the power supply harmonic current, the loop gain of the constant current feedback control is given a gain of 100 Hz or less, which is twice the power supply frequency (50 Hz), for example. In general switching power supplies, a loop gain is ensured from several kHz to several tens of kHz, so that it can be said that the control response is very slow compared to that.

  FIG. 5 is a circuit diagram of a lighting device 110 according to a comparative example with respect to the lighting device 100. Here, consider an operation in a state where no electric charge is accumulated in the output capacitor when the power is turned on. As a comparison, in the lighting device 110 shown in FIG. 5, the position where the output current detection resistor R3 is connected is different from that in FIG. Specifically, one end of the output current detection resistor R3 is connected to the cathode of the LED 5, and the other end of the output current detection resistor R3 is connected to the other end of the output smoothing capacitor C3. Thus, in FIG. 5, the output current detection resistor R3 is connected in series with the LED5. Components having the same configuration between FIG. 5 and FIG. When the AC power supply 1 is turned on, the switching element SW1 starts to be driven, and the output smoothing capacitor C3 is charged. At this time, since the charging voltage of the output smoothing capacitor C3 is lower than the forward voltage at which the LED 5 starts to turn on, no current flows through the LED 5, and the LED 5 is in the light-off state. Therefore, no voltage flows because no current flows through the output current detection resistor R3 during charging of the output capacitor, and the control circuit 4 increases the current supplied to the LED 5, that is, increases the ON time of the switching element SW1. Take control. As a result, the charging current to the output smoothing capacitor C3 increases. However, since the current does not flow through the LED 5 until the voltage of the output smoothing capacitor C3 reaches the forward voltage of the LED 5, the control circuit 4 further turns on the switching element SW1. Works to increase. Next, when the charging voltage of the output smoothing capacitor C3 reaches the forward voltage of the LED 5, a current is supplied to the LED 5, and the LED 5 starts to light. In the lighting device 100, in order to improve the power factor and reduce the power supply harmonic current, the capacities of the input capacitor C1 and the coupling capacitor C2 are smaller than the output smoothing capacitor C3. For example, a film capacitor is used, and the capacity of the output smoothing capacitor C3 is A large-capacity capacitor, for example, an electrolytic capacitor, is used to convert the LED current into a direct current and suppress ripples due to the power supply cycle. For this reason, since charging the output smoothing capacitor C3 requires time, the control circuit 4 greatly increases the on-time of the switching element SW1 by feedback control during that time. For this reason, a very large current flows through the LED 5 immediately after the start of lighting of the LED 5 and the response speed of the constant current feedback control is slow. Therefore, even if the output current detection resistor R3 detects the current flowing through the LED 5, it can respond immediately. However, at least a half period of the power cycle overshoots, and a current significantly exceeding the target current flows. This not only emits an unpleasant flash at the start of LED lighting, but also causes destruction of the LED element by exceeding the rated current of the LED 5.

  Therefore, in the lighting device 100, the output current detection resistor R3 is provided at a position where the charging current to the output smoothing capacitor C3 is detected. When the power is turned on, the switching element SW1 starts driving, and the output smoothing capacitor C3 is charged. At this time, since the voltage of the output smoothing capacitor C3 is lower than the forward voltage at which the LED 5 starts to turn on, no current flows through the LED 5, and the LED 5 is in the unlit state. Even when the LED 5 is turned off, the charging current to the output smoothing capacitor C3 is detected by the output current detection resistor R3, is controlled to a constant current value by the control circuit 4 and is supplied with a stable charging current. The

  Next, when the charging voltage of the output smoothing capacitor C3 reaches the forward voltage of the LED 5, a current is supplied to the LED 5, and the LED 5 starts to light. Since the charging current of the output capacitor is controlled by constant current feedback before the lighting of the LED 5 starts, the LED current does not overshoot immediately after the LED lighting starts. Since the average value of the current supplied to the LED 5 and the average value of the charging current to the output smoothing capacitor C3 are equal, the LED 5 is stably lit by continuously controlling the charging current of the output smoothing capacitor C3 even after the LED lighting is started. be able to.

  As described above, since the charging current of the output smoothing capacitor C3 is controlled before the LED is turned on, the response speed of the constant current feedback control is set to 1/2 or more of the power cycle for power factor improvement control and harmonic current suppression. Even so, the LED current overshoot after the LED is turned on can be suppressed. As a result, unpleasant flashing immediately after the LED is turned on, and destruction of the LED element due to exceeding the rated current of the LED can be prevented.

  As described above, the lighting device 100 which is an example of the lighting device to which the present invention can be applied has a current peak value of the inductor L1 as a sine wave and a current supplied to the LED 5 is a desired current value in the SEPIC circuit. Thus, the switching element SW1 is controlled. Thereby, power factor improvement control and constant current control can be realized by one converter, and the number of parts can be reduced. Moreover, according to the lighting device 100, since a transformer is not used for power conversion, a power conversion loss due to the transformer can also be reduced. Accordingly, it is possible to provide a lighting device that can realize a reduction in circuit size and cost, and that achieves a high power factor and high efficiency. Furthermore, since the constant current control is performed by detecting the charging current of the capacitor, it is possible to prevent unpleasant flashing immediately after the LED is turned on, and destruction of the LED element due to exceeding the rated current of the LED 5.

  Note that the SEPIC system power supply has been described as an example of a lighting device to which the present invention can be applied. However, in addition to the SEPIC system, any converter that performs power factor improvement (harmonic current reduction) and constant current control with one converter can be used. Other methods may be used. For example, a flyback lighting device 120 shown in FIG. 6 is an example of a lighting device to which the present invention can be applied.

  The lighting device 120 illustrated in FIG. 6 includes a filter capacitor C11, a transformer T1, a switching element SW2, a diode D11, an output smoothing capacitor C4, and an output current detection resistor R4. The filter capacitor C11 is connected in parallel to the two DC output terminals of the rectifier circuit 2 in the same manner as the filter capacitor C1 in the lighting device 100 of FIG. The transformer T1 includes a primary winding and a secondary winding that is magnetically coupled to the primary winding. One end of the primary winding of the transformer T1 is connected to one end of the filter capacitor C11. The switching element SW2 includes a first terminal, a second terminal, and a control terminal that switches between the first and second terminals. The first terminal is connected to the other end of the primary winding of the transformer T1, and the second terminal The terminal is connected to the other end of the filter capacitor C11. In the lighting device 120 shown in FIG. 6, the switching element SW2 is a MOSFET, the first terminal is a drain, the second terminal is a source, and the control terminal is a gate. The anode of the diode D11 is connected to one end of the secondary winding of the transformer T1. The output smoothing capacitor C4 is connected to the cathode of the diode D11, is connected in parallel with the secondary winding of the transformer T1 via the diode D11, and is connected in parallel with the LED 5. The output current detection resistor R4 is a resistance element provided in series in a path connecting the secondary winding of the transformer T1 and the output smoothing capacitor C4.

  Also in the flyback lighting device 120 shown in FIG. 6, the same effect can be obtained by arranging the output current detection resistor R4 at the position where the charging current of the output smoothing capacitor C4 flows and performing constant current control. It is possible to prevent an unpleasant flash immediately after the LED is turned on and destruction of the LED element due to exceeding the rated current of the LED. Although only the main circuit configuration is shown in FIG. 6 and description of the control circuit 20 is omitted, the control circuit 20 drives and controls the switching element SW2, and the output current is detected at the position where the charging current to the output smoothing capacitor C4 is detected. The detection resistor R4 is arranged, and the control circuit 20 performs power factor improvement and harmonic reduction by setting the response speed of the constant current feedback control to a half cycle or more of the power cycle.

  In the above description, for the purpose of power factor improvement control and harmonic current reduction, the response speed of constant current feedback control is set to twice or less the power supply frequency (1/2 or more of the power supply period), and the output current Although the detection resistor is arranged at a position where the charging current of the output smoothing capacitor is detected, the lighting device to which the present invention is applicable is not limited to this. Even in applications that do not require power factor improvement and harmonic current reduction, the output current detection resistors R3 and R4 may be arranged at a position where the charging current of the output smoothing capacitors C3 and C4 is detected. It is effective in preventing the flash immediately after the start.

  That is, in applications that do not require power factor improvement and harmonic current reduction, the LED current can be controlled at high speed by setting the constant current feedback control response speed to, for example, several kHz to several tens of kHz. Therefore, even if the voltage of the output smoothing capacitor reaches the forward voltage of the LED 5 and the LED current overshoots immediately after the start of lighting, it can be rapidly reduced to the target value current value. It is possible to prevent a current from flowing. However, even if the target current value is slightly exceeded for a short period of time, the human eye can detect it, so that there is a problem that it is recognized as a flash. Even in such a case, according to each circuit exemplified as the lighting device to which the present invention can be applied, the output current detection resistors R3 and R4 are arranged at the positions for detecting the charging currents of the output smoothing capacitors C3 and C4. Constant current feedback is possible before the LED 5 starts lighting, and flashing can be suppressed.

  In the above description, the LED 5 is used as the light source. However, for example, an organic EL (Electro Luminescence) element may be used as the light emitting element of the light source.

  Note that the switching element SW1 described above is configured by a semiconductor switch. As the semiconductor switch, for example, a MOSFET, a power transistor (bipolar transistor), or an IGBT (insulated gate bipolar transistor) may be used. Alternatively, a switching element formed of a wide band gap semiconductor such as gallium nitride and silicon carbide (SiC) may be used, and in particular, a MOSFET formed of SiC may be used.

Embodiment 1 FIG.
FIG. 7 is a circuit configuration diagram of the lighting device 130 according to the first embodiment of the present invention. The same components as those of the lighting device to which the present invention can be applied (specifically, the lighting devices 100 and 120) are denoted by the same reference numerals, and description thereof is omitted. The difference between the first embodiment and the lighting device to which the present invention can be applied is that a selection circuit 132 including diodes D2 and D3 and a control power supply circuit 30 for driving the control circuit 4 are provided. . The internal circuit of the control circuit 4 already described with reference to FIG. 1 and the like is omitted in FIG. However, the internal configuration of the control circuit 4 and the following connection relationship are the same as those described with reference to FIG.

  The control power supply circuit 30 supplies a control power supply for the operation of the control circuit 4, for example, generates a voltage of 15 V and supplies power to an operational amplifier, a comparator, or a microcomputer constituting the control circuit 4. is there.

  The control power supply circuit 30 constitutes a step-down converter circuit, for example. As shown in FIG. 7, the control power supply circuit 30 includes a switching element SW3, a drive circuit 32 that applies a drive signal to the control terminal of the switching element SW3, a diode D31, a choke coil L31, and an output smoothing capacitor C5. ing. The first terminal of the switching element SW3 is connected to the output of the selection circuit 132 (that is, the cathode in the diode OR circuit) described later. The second terminal of the switching element SW3 is connected to the cathode of the diode D31. The anode of the diode D31 is connected to the reference potential GND. One end of the choke coil L31 is connected to a connection point between the second terminal of the switching element SW3 and the cathode of the diode D31. One end of the output smoothing capacitor C5 is connected to the other end of the choke coil L31, and the other end of the output smoothing capacitor C5 is connected to the anode of the diode D31. In the first embodiment, the switching element SW3 is a MOSFET, the first terminal is a drain, the second terminal is a source, and the control terminal is a gate. In such a circuit configuration, one end of the output smoothing capacitor C5 serves as a positive terminal, and control power is supplied to the control circuit 4 from the positive terminal.

  The lighting device 130 includes a selection circuit 132. The selection circuit 132 selects and controls one of a power path from the DC output of the rectifier circuit 2 to the control power circuit 30 and a power path from the output smoothing capacitor C3 to the control power circuit 30. Power is supplied to the power supply circuit 30. The selection circuit 132 is constituted by a so-called diode OR circuit composed of a cathode common connection of the diode D2 and the diode D3. The positive output terminal of the rectifier circuit 2 is connected to the input side of the control power supply circuit 30 via the diode D <b> 2, and the full-wave rectified voltage is applied to the control power supply circuit 30. Furthermore, the positive side terminal of the output smoothing capacitor C3 is connected to the input side of the control power supply circuit 30 via the diode D3. The control circuit 4 is connected to the output side of the control power supply circuit 30 to supply control power.

  The diode D2 and the diode D3 constitute a diode OR circuit in which the higher one of the voltage on the DC side of the rectifier circuit 2 and the voltage of the output smoothing capacitor C3 is conducted. That is, when the voltage on the DC side of the rectifier circuit 2 is higher than the output smoothing capacitor C3 voltage, the diode D2 is turned on. When the voltage of the output smoothing capacitor C3 is higher than the voltage on the DC side of the rectifier circuit 2, the diode D3 is turned on.

  Next, a specific operation will be described. When the AC power supply 1 is turned on, the rectifier circuit 2 full-wave rectifies the AC voltage to generate a DC voltage. At this time, the LED 5 is turned off, and the output smoothing capacitor C3 is not charged. Therefore, the voltage on the DC side of the rectifier circuit 2 becomes higher, and the diode D2 becomes conductive and is applied to the control power supply circuit 30.

  When a voltage is applied from the diode D2, the control power supply circuit 30 starts the operation of the switching element SW3, and generates a desired voltage, for example, 15V from the applied voltage. When a desired voltage is output from the output of the control power supply circuit 30, the control circuit 4 is activated in response to this, and drives and controls the converter unit 3. The operation of the control circuit 4 is the same as that of the lighting device to which the present invention can be applied (specifically, the lighting devices 100 and 120), and a description thereof will be omitted. When the converter unit 3 starts driving, the output smoothing capacitor C3 is charged and the LED 5 is lit. After the LED is turned on, power is supplied from either the DC side of the rectifier circuit 2 or the output smoothing capacitor C3 according to the phase angle of the AC power supply, and the control power supply circuit 30 generates a control power supply.

  Since power cannot be supplied from the output smoothing capacitor C3 when the converter unit 3 is not operating, power is supplied to the control power supply circuit 30 only from the DC side of the rectifier circuit 2 via the diode D2. Since the power consumption of the control circuit 4 is very small compared to the power consumption of the LED 5, the full-wave rectified voltage is smoothed by the filter capacitor C1 and becomes a substantially constant voltage.

  On the other hand, since the converter unit 3 operates and the power consumption is large while the LED is lit, a non-smooth full-wave rectified voltage waveform is obtained. For this reason, a voltage value changes according to the phase angle of AC power supply voltage. Therefore, as shown in FIG. 8, when the full-wave rectified voltage of the rectifier circuit 2 becomes lower than the voltage of the output smoothing capacitor C3 due to the phase angle of the AC power supply 1, the diode D3 is turned on to supply power from the output smoothing capacitor C3. Generate control power. When the full-wave rectified voltage becomes higher than the output smoothing capacitor C3 voltage due to the phase angle of the AC power supply 1, the diode D2 is turned on to supply power from the AC power supply 1 to generate a control power supply. Here, the diode D2 and the diode D3 in FIG. 8 indicate a conductive diode when the control power supply circuit 30 supplies the control power to the control circuit 4, and indicate that the diode indicated as ON is conductive. ing.

  Here, suppose that the diode D3 is not connected and only the diode D2 is connected to generate power for operation of the control circuit 4. In this case, power is not supplied from the output smoothing capacitor C3 even when the output smoothing capacitor C3 is charged.

  When a step-down converter is used for the control power supply circuit 30, for example, assuming that the output voltage of the control power supply circuit 30 is 15V, in principle, the voltage on the DC side of the rectifier circuit 2, that is, in a section where the full-wave rectified voltage waveform is less than 15V. The control power supply circuit 30 cannot generate 15V. Further, depending on the control IC of the step-down converter used, an input voltage exceeding 15V may be required (for example, 50V or more is required). Further, even if a circuit system other than the step-down converter is used, the input voltage decreases to almost zero volts in the vicinity of the zero cross of the commercial AC power supply, so that a period during which the control power supply circuit cannot operate occurs.

  Therefore, when the full-wave rectified voltage becomes equal to or lower than the operating voltage of the control power supply circuit 30 due to the phase angle of the AC power supply 1, the control power supply circuit 30 stops operating and cannot generate the control power supply. In this case, power is supplied to the control circuit from the output smoothing capacitor C5 provided in the control power supply circuit 30. Again, when the full-wave rectified voltage becomes equal to or higher than the operating voltage of the control power supply circuit 30, the control power supply circuit 30 starts operating and generates a control power supply.

  The input current waveform of the lighting device 130 at the time of generating the control power supply is a waveform in which the current flowing into the inductor L1 is superimposed on the current flowing into the diode D2. That is, a waveform in which the inflow current to the diode D2 is superimposed on the current flowing through the inductor L1 only when the full-wave rectified voltage of the AC power supply 1 is equal to or higher than the operable voltage of the control power supply circuit 30. That is, since the current flowing into the diode D2 flows only during the ON period of the diode D2 shown in FIG. 8, the current flows for one cycle of the commercial frequency, that is, the conduction angle is small. When the conduction angle is reduced, the necessary power is obtained in a short period of time, so that the peak value of the inflow current is increased correspondingly, causing a reduction in power factor and an increase in harmonic current.

  Further, since the power is supplied to the control circuit 4 only from the output smoothing capacitor C5 while the control power supply circuit 30 is stopped, that is, during the OFF period of the diode D2 shown in FIG. 8, the charging voltage of the output smoothing capacitor C5 decreases. When the full-wave rectified voltage rises again and the control power supply circuit 30 operates, a phenomenon occurs in which the current flowing into the diode D2 increases to compensate for this voltage drop. For this reason, the amount of current superimposed from the diode D2 cannot be ignored, which causes a decrease in power factor and an increase in harmonic current. Further, the output smoothing capacitor C5 needs to have a large capacity, which leads to an increase in substrate size and cost.

  This decrease in power factor and increase in harmonic currents may become more prominent when the light output (brightness) of the LED is lowered, particularly in a lighting device provided with a dimming function. This is because the power consumption of the control circuit 4 increases during dimming, the power consumption of the LED 5 decreases, and the current flowing through the inductor L1 decreases. In other words, the ratio of the current flowing into the diode D2 is relatively increased with respect to the current flowing through the inductor L1, causing a power factor deterioration and an increase in harmonic current. The reason why the power consumption of the control circuit 4 increases during dimming is that, due to the operation principle, the drive frequency of the switching element SW1 increases as the light load during dimming increases. Is used, the number of times of charging / discharging the MOSFET gate input capacitance of the driving circuit 14 increases, and the driving power of the MOSFET increases.

  Therefore, in the first embodiment, in addition to the lighting devices 100 and 120 described above, the DC side of the rectifier circuit 2 and the output smoothing capacitor C3 are formed by the diode D2 and the diode D3 in order to further improve the power factor and reduce the harmonic current. Both of them can supply power to the control power supply circuit 30. In this case, since the power is supplied from the output smoothing capacitor C3 when the voltage of the output smoothing capacitor C3 is higher than the DC voltage of the rectifying circuit 2, the DC voltage of the rectifying circuit 2 is higher than the voltage of the output smoothing capacitor C3. The current value flowing into the diode D2 can be small, and power factor deterioration and increase in harmonic current can be suppressed. Since the control power supply circuit 30 can always operate regardless of the phase angle of the AC power supply 1, a small output smoothing capacitor C5 of the control power supply circuit 30 can be used.

  As described above, in the one-converter type lighting device 130 that performs power factor improvement control and constant current control, a path through which power can be supplied from both the DC side of the rectifier circuit 2 and the output smoothing capacitor C3 is provided. When the voltage on the DC side is lower than the output smoothing capacitor C3, the power for generating the control power supply can be supplied from the output smoothing capacitor C3 to the control power supply circuit 30. The inflowing current can be reduced, and the power factor reduction and the increase of the harmonic current can be suppressed.

  Furthermore, in the lighting device 130, by adopting a SEPIC circuit, power factor improvement control and constant current control can be realized by one converter, and the number of parts can be reduced. In addition, since a transformer is not used for power conversion, power conversion loss due to the transformer can be reduced. Accordingly, it is possible to provide a lighting device that can realize a reduction in circuit size and cost, and that achieves a high power factor and high efficiency.

  In the first embodiment, the SEPIC system power supply has been described. In addition, for example, in the flyback system lighting device 140 that achieves both power factor improvement control and constant current control with one converter shown in FIG. A power supply circuit 30 and a selection circuit 132 may be provided. After the LED is lit by the diode OR connection from the DC side of the rectifier circuit 2 and the output smoothing capacitor C4, power is supplied from either the DC side of the rectifier circuit 2 or the output smoothing capacitor C4 according to the phase angle of the AC power supply 1. The control power supply circuit 30 may generate a control power supply. Thereby, the same effect can be acquired.

  In the first embodiment, the output current detection resistor R3 in FIG. 7 and the output current detection resistor R4 in FIG. 9 are the same as the lighting device to which the present invention can be applied (specifically, the lighting devices 100 and 120). Similarly, it is provided at a position for detecting the charging current of the output smoothing capacitors C3 and C4. Thereby, there is an advantage that both the effect of the lighting device to which the present invention can be applied (specifically, the lighting devices 100 and 120) and the effect of the first embodiment can be obtained. However, the lighting devices 130 and 140 according to the first embodiment may be modified as described below. 10 and 11 show lighting devices 150 and 160 according to the modification of the first embodiment, respectively. The lighting devices 150 and 160 have the same circuit configuration as each of the lighting devices 130 and 140 except for the connection position of the output current detection resistors R3 and R4. In the lighting devices 150 and 160, output current detection resistors R3 and R4 are provided at positions where the current flowing through the LED 5 is detected (that is, in series with the LED 5). In this case, as shown in FIGS. 10 and 11, one end of each of the output current detection resistors R3, R4 is connected to the cathode of the LED 5, and the other end of each of the output current detection resistors R3, R4 is the output smoothing capacitor C3, C4. It is connected to each other end. Also in this case, since the lighting devices 150 and 160 include the selection circuit 132 and the control power supply circuit 30, the effects described in the first embodiment can be obtained similarly.

  The lighting device including the lighting devices 150 and 160 described here is, for example, “a rectifier circuit that converts an AC voltage into a DC voltage and a DC output terminal of the rectifier circuit, and an output smoothing capacitor between the load output terminals. A conversion circuit for supplying a direct current to a light source connected in parallel with the output smoothing capacitor, a current detection unit for detecting a current flowing through the light source, and a current detected by the current detection unit A control circuit that feedback-controls the conversion circuit so as to approach a target current value; and a control power supply circuit that supplies driving power to the control circuit, wherein the control power supply circuit is supplied with a direct current to the light source. During this period, at least in the vicinity of the zero cross of the AC voltage, power is supplied from the output smoothing capacitor to generate driving power for the control circuit. It may be provided as a location ".

Embodiment 2. FIG.
FIG. 12 is a cross-sectional view of the lighting apparatus 200 according to the second embodiment of the present invention. The lighting fixture 200 includes a lighting fixture body 40, a connector 41, a light source substrate 42, and a lighting device 43. The luminaire main body 40 is a housing for attaching the lighting device 43 and the like. The connector 41 is a connection part for receiving power supply from an AC power source such as a commercial power source. The light source substrate 42 is a substrate on which an electrical light source such as an LED is mounted.

  The lighting device 43 inputs power from an AC power source via the connector 41 and the wiring 44. The lighting device 43 converts the input power into power supplied to the light source substrate 42. The lighting device 43 is connected to the light source substrate 42 via the wiring 45. The lighting device 43 supplies the converted power to the light source substrate 42. The light source of the light source substrate 42 is turned on by the power supplied from the lighting device 43.

  The circuit configuration of the lighting device 43 is the same as that of the lighting device 130 according to the first embodiment. Thereby, the lighting device 43 and the lighting fixture 200 provided with the advantage of the lighting device 130 concerning Embodiment 1 are provided.

  The circuit configuration of the lighting device 43 may be the same as that of one lighting device selected from the group consisting of the lighting devices 140, 150, and 160 according to the first embodiment, instead of the lighting device 130.

  According to the lighting apparatus 200 according to the second embodiment, by incorporating the lighting device described in the first embodiment, the lighting apparatus can be reduced in size, high efficiency, low cost, high efficiency, and lighting can be started. It is possible to prevent the unpleasant flash immediately after that and the destruction of the light source due to exceeding the rated current of the light source.

  2 rectifier circuit, 3 converter unit, 4 control circuit, 5 LED 9 error amplifier, 10 first comparator, 11 flip-flop circuit, 12 signal generator, 13 second comparator, 14 drive circuit, 20 control circuit, 30 control Power supply circuit, 40 lighting fixture body, 41 connector, 42 light source board, 43 lighting device, 44, 45 wiring, 100, 110, 120, 130, 140, 150, 160 lighting device, 132 selection circuit, 200 lighting fixture, L1 1st 1 inductor, L2 2nd inductor, L31 choke coil, C1 input capacitor, C2 coupling capacitor, C3, C4, C5 output smoothing capacitor, D1, D2, D3, D31 diode, SW1, SW2, SW3 switching element, R3, R4 Output current detection resistor, T1 transformer, E1 1 reference voltages, E2 second reference voltage

Claims (5)

A rectifier circuit that converts alternating voltage to direct voltage;
A conversion circuit connected between the DC output terminals of the rectifier circuit, having an output smoothing capacitor between the load output terminals, and supplying a DC current to the light source;
A control circuit for driving and controlling the conversion circuit;
With
The control circuit operates by receiving power for driving the control circuit from a control power supply circuit,
While a direct current is supplied to the light source, the control power supply circuit receives power from the output smoothing capacitor at least in the vicinity of a zero cross of the alternating voltage to generate driving power for the control circuit,
Either a power path from the DC output of the rectifier circuit to the control power supply circuit or a power path from the output smoothing capacitor to the control power supply circuit is selected to supply power to the control power supply circuit. A lighting device further comprising a selection circuit for supplying.   The selection circuit includes a diode OR circuit including a cathode common connection of a first diode and a second diode, an anode of the first diode is connected to a DC output of the rectifier circuit, and a cathode of the first diode is the control 2. The lighting device according to claim 1, wherein the lighting device is connected to an input of a power supply circuit, an anode of the second diode is connected to the output smoothing capacitor, and a cathode of the second diode is connected to an input of the control power supply circuit.   The lighting device according to claim 1, wherein the conversion circuit is a SEPIC circuit.   The lighting device according to claim 1, wherein the conversion circuit is a flyback converter circuit. A light source comprising a light emitting element;
A lighting device for lighting the light source;
With
The lighting device is
A rectifier circuit that converts alternating voltage to direct voltage;
A conversion circuit connected between the DC output terminals of the rectifier circuit, having an output smoothing capacitor between the load output terminals, and supplying a DC current to the light source;
A control circuit for driving and controlling the conversion circuit;
With
The control circuit operates by receiving power for driving the control circuit from a control power supply circuit,
While a direct current is supplied to the light source, the control power supply circuit receives power from the output smoothing capacitor at least in the vicinity of a zero cross of the alternating voltage to generate driving power for the control circuit,
Either a power path from the DC output of the rectifier circuit to the control power supply circuit or a power path from the output smoothing capacitor to the control power supply circuit is selected to supply power to the control power supply circuit. A luminaire further comprising a selection circuit for supplying.

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