JP2019175836A - Lighting system, illumination device, and lighting fixture - Google Patents

Abstract

To provide a lighting system, an illumination device and a lighting fixture, capable of reducing flickering light emitted from a light source even when the input voltage value fluctuates instantaneously.SOLUTION: In a control circuit 1e, a target current value of a load current Io is set in accordance with an instruction value of a light control level of a light source 12. Moreover, in the control circuit 1e, the on-duty of a switching element of a power supply circuit 110 is adjusted so that deviation between the detected current value of the load current Io based on a current detection signal Sd and the target current value is made small. Then, in the control circuit 1e, the on-duty control value is obtained by multiplying the deviation by a feedback gain and the feedback gain is set in accordance with the instruction value of the light control level.SELECTED DRAWING: Figure 1

Description

  The present invention generally relates to lighting systems, lighting devices, and lighting fixtures.

  Conventionally, as shown in Patent Document 1, a lighting circuit including a power conversion unit and a control unit is provided. The power conversion unit is connected to the dimmer via the power supply path and further connected to the illumination load. The power conversion unit is supplied with the phase-controlled AC voltage from the dimmer, and supplies the DC voltage to the illumination load by turning on and off the switching element.

  Then, the power conversion unit detects the conduction angle of the AC voltage, and controls the conversion of power according to the detected conduction angle, thereby dimming the illumination load according to the detected conduction angle. Furthermore, the power conversion unit detects a current flowing through the lighting load and controls a current flowing through the lighting load based on the detected current. For example, the power converter controls the current flowing through the lighting load to be substantially constant.

Japanese Patent Laying-Open No. 2015-185360

  However, in the above-described conventional lighting circuit (lighting system), when the value of the input AC voltage fluctuates instantaneously, the peak value of the current flowing through the switching element when the switching element is turned on fluctuates. ) Also varies. As a result, the amount of light emitted from the illumination load may fluctuate due to instantaneous fluctuations in the value of the input AC voltage, causing light flickering.

  Accordingly, an object of the present invention is to provide a lighting system, a lighting device, and a lighting fixture that can reduce flickering of light emitted from a light source even when the value of an input voltage fluctuates instantaneously. There is.

  A lighting system according to one embodiment of the present invention includes a power supply circuit, a current detection circuit, and a control circuit. The power supply circuit is supplied with AC power from an AC power supply, and supplies a DC load current to the light source by controlling the on-duty of the switching element. The current detection circuit outputs a current detection signal corresponding to the magnitude of the load current. The control circuit sets a target current value of the load current according to an indication value of a dimming level of the light source, and a detected current value indicating the magnitude of the load current based on the current detection signal and the target current value The difference is taken as the deviation. The control circuit obtains a control value of the on-duty of the switching element for reducing the deviation by multiplying the deviation by a feedback gain, and adjusts the on-duty based on the control value. Then, the control circuit sets the feedback gain according to the indicated value of the dimming level.

  An illumination device according to one embodiment of the present invention includes the above lighting system and a light source to which the load current is supplied from the lighting system.

  The lighting fixture which concerns on 1 aspect of this invention is equipped with the above-mentioned lighting system, the light source to which the said load current is supplied from the said lighting system, and the housing | casing by which the said light source is supported at least.

  As described above, the present invention has an effect that flickering of light emitted from the light source can be reduced even when the value of the input voltage fluctuates instantaneously.

FIG. 1 is a block diagram illustrating an illumination system including a lighting system according to an embodiment. FIG. 2 is a waveform diagram showing waveforms at various parts of the lighting system. FIG. 3 is a static characteristic diagram showing the relationship between the on-duty and load current of the lighting system. FIG. 4 is a characteristic diagram showing gain characteristics and phase characteristics when the lighting system of the above is fully lit. FIG. 5 is a characteristic diagram showing gain characteristics and phase characteristics when the dimming lighting of the above lighting system is performed. FIG. 6 is a block diagram showing a lighting system according to the first modified example. FIG. 7 is a block diagram showing a lighting system according to the second modified example. FIG. 8 is a block diagram showing a configuration example of the load voltage detection circuit of the lighting system according to the third modified example. FIG. 9 is a waveform diagram showing voltage waveforms of the lighting system. FIG. 10 is a block diagram showing another configuration example of the load voltage detection circuit of the above. FIG. 11A is a cross-sectional view showing a lighting fixture including the lighting system. FIG. 11B is a cross-sectional view showing another lighting fixture including the lighting system.

  The following embodiments generally relate to lighting systems, lighting devices, and lighting fixtures. More specifically, the present invention relates to a lighting system, a lighting device, and a lighting fixture that are supplied with an AC voltage and supply a load current to a light source by turning on and off a switching element. The embodiment described below is only an example of the embodiment of the present invention. The present invention is not limited to the following embodiments, and various modifications can be made according to design and the like as long as the effects of the present invention can be achieved.

  The lighting system, lighting device, and lighting fixture of the embodiment are mainly used in a dwelling unit, an office, a factory, a store, or the like. The dwelling unit may be either a detached house or an apartment house.

  Embodiments will be described below with reference to the drawings.

  Illumination system A1 of embodiment is provided with the illuminating device 1 and the light control device 2, as shown in FIG. A series circuit of the lighting device 1 and the dimmer 2 is connected between both ends of the AC power supply 9. The AC power supply 9 is a commercial power supply having a frequency of 50 Hz or 60 Hz.

  The dimmer 2 controls the phase of the AC voltage Va supplied from the AC power supply 9 to the lighting device 1. That is, the lighting device 1 receives the voltage (phase control voltage Vb) whose phase is controlled by the dimmer 2. The dimmer 2 adjusts the conduction angle, which is the energization period for each half wave of the phase control voltage Vb, so that the lighting device 1 performs dimming according to the conduction angle. In this case, the conduction angle corresponds to the instruction information indicating the instruction value of the light control level of the light source 12.

  The lighting device 1 is a lighting fixture capable of dimming, and includes a lighting system 11 and a light source 12 as shown in FIG. The lighting system 11 and the light source 12 may be housed in a common housing and configured integrally, or the lighting system 11 and the light source 12 may be configured separately.

  The lighting system 11 includes a power supply circuit 110, a rectifier circuit 1a, a phase detection circuit 1d, a control circuit 1e, a drive circuit 1f, a starting circuit 1g, a first control power supply 1h, a second control power supply 1i, a current detection circuit 1j, and a voltage detection. A circuit 1k is provided. The power supply circuit 110 includes a converter 1b and a capacitor 1c.

  The rectifier circuit 1a is a full-wave rectifier circuit having a diode bridge or the like, and receives the phase control voltage Vb phase-controlled by the dimmer 2. The rectifier circuit 1a full-wave rectifies the phase control voltage Vb and outputs a pulsating voltage Vc. FIG. 2 shows the waveform of the pulsating voltage Vc. The pulsating voltage Vc in FIG. 2 is phase-controlled in the same manner as the phase control voltage Vb, and a conduction angle θ is a period in which the half-wave is energized. In FIG. 2, the alternate long and short dash line indicates the waveform of the full-wave rectified voltage Ve obtained by full-wave rectifying the AC voltage Va. Furthermore, you may have a filter circuit in the front | former stage of the rectifier circuit 1a. The filter circuit includes, for example, an inductor and capacitor for noise removal, and a surge absorber, and attenuates unnecessary frequency components (for example, high frequency noise).

  The power supply circuit 110 receives the pulsating voltage Vc and outputs a DC output voltage Vo.

  Specifically, converter 1b converts pulsating voltage Vc into a DC voltage and outputs the DC voltage to capacitor 1c. The capacitor 1c smoothes the DC voltage output from the converter 1b, and a DC output voltage Vo is generated between both ends of the capacitor 1c. The converter 1b is an AC / DC converter (switching power supply circuit) having a semiconductor switching element, and the pulsating voltage Vc is converted into an output voltage Vo when the semiconductor switching element is turned on and off.

  Converter 1b preferably constitutes a single stage converter (SS converter). The SS converter is a one-converter type (one voltage conversion) converter having a power factor correction circuit function and an AC / DC converter function. For example, converter 1b is preferably a buck-boost converter having a power factor improving function.

  The light source 12 includes a plurality of LEDs (Light Emitting Diodes) as a plurality of solid state light emitting elements, and is connected in series to the current detection circuit 1j. A series circuit of the light source 12 and the current detection circuit 1j is connected between both ends of the capacitor 1c, and is applied with the output voltage Vo of the power supply circuit 110. The light source 12 emits illumination light when supplied with the load current Io from the power supply circuit 110. In addition, several LED which the light source 12 has is connected in series, or series connection and parallel connection.

  The phase detection circuit 1d corresponds to an information acquisition unit that receives instruction information indicating an instruction value of the light control level of the light source 12 from the outside. In the present embodiment, the conduction angle θ of the pulsating voltage Vc (conduction angle of the phase control voltage Vb) corresponds to the instruction information. The phase detection circuit 1d compares the pulsating voltage Vc with the determination reference value, and outputs a PWM signal generated based on the comparison result as the phase detection signal Sa. The phase detection signal Sa is a pulse signal synchronized with the phase control voltage Vb, and the on-duty of the phase detection signal Sa corresponds to the magnitude of the conduction angle θ. Specifically, when the conduction angle θ increases, the on-duty of the phase detection signal Sa increases, and when the conduction angle θ decreases, the on-duty of the phase detection signal Sa decreases.

  The control circuit 1e includes a computer system, and the computer system mainly includes a processor and a memory as hardware. And the function of the control circuit 1e in this embodiment is implement | achieved when a processor runs the program recorded on memory. The program may be recorded in advance in the memory of the computer system, but may be provided through an electric communication line, or may be stored in a non-temporary recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. It may be recorded and provided. A processor of a computer system includes one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The plurality of electronic circuits may be integrated on one chip, or may be distributed on the plurality of chips. The plurality of chips may be integrated into one device, or may be distributed and provided in a plurality of devices.

  The first control power source 1h receives electric power from the starting circuit 1g or the converter 1b, and outputs a first DC control voltage Vd1. The first control voltage Vd1 becomes the operating voltage of the drive circuit 1f.

  The starting circuit 1g outputs the pulsating voltage Vc to the first control power source 1h in the start-up period immediately after the power supply from the AC power source 9 to the lighting system 11 via the dimmer 2 is started. In the start-up period, the first control power source 1h receives the pulsating voltage Vc and outputs the first control voltage Vd1.

  And if it transfers to a steady period from a starting period, the starting circuit 1g will stop the output of the pulsating voltage Vc. On the other hand, converter 1b includes a transformer and a switching element. In a steady period, the current flowing in the primary winding of the transformer is turned on and off by a switching operation for turning on and off the switching element. The induced voltage generated in the secondary winding of the transformer is supplied to the first control power source 1h. That is, in the steady period, the first control power source 1h receives the induced voltage due to the switching operation of the converter 1b and outputs the first control voltage Vd1.

  The drive circuit 1f operates by the first control voltage Vd1, receives the switching control signal Sb from the control circuit 1e, and generates the drive signal Sc based on the switching control signal Sb. Then, drive circuit 1f outputs drive signal Sc to converter 1b to drive the switching element of converter 1b on and off.

  The second control power source 1i receives the first control voltage Vd1 and outputs a DC second control voltage Vd2. The second control voltage Vd2 becomes the operating voltage of the control circuit 1e. In the present embodiment, the second control voltage Vd2 is a voltage value lower than the first control voltage Vd1, but the magnitude relationship between the first control voltage Vd1 and the second control voltage Vd2 is not limited to this relationship. The first control power source 1h and the second control power source 1i may be either a switching power source or a linear power source.

  The current detection circuit 1j includes, for example, a current detection resistor through which the load current Io flows, and outputs the voltage across the current detection resistor to the control circuit 1e as a current detection signal Sd. In this case, the current detection signal Sd is a voltage signal having a voltage value proportional to the magnitude of the load current Io, and the voltage value of the current detection signal Sd corresponds to the detection current value. That is, the detected current value represents the magnitude of the load current Io based on the current detection signal Sd.

  The voltage detection circuit 1k includes a series circuit of voltage dividing resistors connected between both ends of the capacitor 1c, and outputs a voltage obtained by dividing the output voltage Vo to the control circuit 1e as a voltage detection signal Se. In this case, the voltage detection signal Se is a voltage signal having a voltage value proportional to the magnitude of the output voltage Vo, and the voltage value of the voltage detection signal Se corresponds to the voltage detection value.

  Then, the control circuit 1e generates a switching control signal Sb based on the phase detection signal Sa, the current detection signal Sd, and the voltage detection signal Se, and outputs the switching control signal Sb to the drive circuit 1f.

  Specifically, the control circuit 1e reads the magnitude of the conduction angle θ from the phase detection signal Sa based on the on-duty (corresponding to the dimming level instruction value) of the phase detection signal Sa, and the magnitude of the conduction angle θ. The target current value (target current value) of the load current Io is determined accordingly. Then, the control circuit 1e controls the switching control signal Sb for adjusting the on-duty of the switching element of the converter 1b so that the deviation (difference) between the detected current value and the target current value becomes small (approaching to zero). Is generated. That is, the control circuit 1e performs feedback control for adjusting the on-duty of the switching element of the converter 1b so that the deviation between the detected current value and the target current value becomes small. As a result, the load current Io is subjected to constant current control so that the dimming level of the light source 12 becomes the indicated value of the dimming level. Since the indication value of the light control level is higher as the conduction angle θ is larger, the target current value is larger as the conduction angle θ is larger. Further, the smaller the conduction angle θ is, the lower the dimming level instruction value is. Therefore, the smaller the conduction angle θ is, the smaller the target current value is.

  Further, the control circuit 1e determines whether or not an overvoltage state of the output voltage Vo has occurred based on the voltage detection value (the voltage value of the voltage detection signal Se). If the control circuit 1e determines that an overvoltage condition has occurred, the control circuit 1e sets the target current value to zero and generates the switching control signal Sb so that the value of the load current Io becomes zero. That is, the control circuit 1e stops outputting the output voltage Vo when an overvoltage state occurs.

  In the lighting system 11 described above, since the converter 1b is an SS converter, the load current Io can be controlled by a single voltage conversion, and cost reduction and electrical efficiency can be improved.

  Conventionally, general-purpose analog control ICs (Integrated Circuits) have been widely used for switching control of SS converters. The analog control IC obtains a deviation between the detected current value and the target current value. Then, the analog control IC performs feedback control of the switching element so that the obtained deviation becomes zero. At this time, the analog control IC controls the switching element so that the average value of the on-time of the switching element of the SS converter becomes a substantially fixed value. In the switching control using the analog control IC, the power factor can be easily improved because the peak value for each switching period is determined according to the sine waveform of the AC voltage Va for the current flowing through the switching element (switching current).

  However, a ripple current having a frequency twice the frequency (50 Hz or 60 Hz) of the input AC voltage is superimposed on the load current output from the SS converter. As a result, the following problems occur when the light source is dimmed. First, when the value of the input AC voltage (input voltage) instantaneously varies due to disturbance or noise, the peak value of the switching current varies when the switching element of the SS converter is turned on, so the load current also varies. Arise. As a result, the amount of light emitted from the light source may fluctuate due to instantaneous fluctuations in the value of the input AC voltage, causing light flickering.

  For example, a general-purpose analog control IC obtains a control value for the on-time of a switching element by multiplying a deviation between a detected current value and a target current value by a feedback gain. At this time, the feedback gain that determines the ON time is uniquely determined by the constants of the peripheral circuits of the analog control IC. Therefore, when an optimum feedback gain is set for all lighting states, there is a problem such that the feedback gain is too small in the dimming lighting state. For this reason, the responsiveness (followability) and stability of the feedback control that changes the ON time following the instantaneous fluctuation of the value of the AC voltage are relatively low, and the fluctuation of the load current is likely to occur.

  Further, when the phase control method for controlling the phase of the AC voltage is adopted as the dimming method, not only the load current but also the input voltage varies, so the effective value of the phase control voltage also varies. For this reason, the control of the switching element becomes more complicated, and it has been more difficult to achieve both stability and followability with a general-purpose analog control IC. Therefore, conventionally, when the phase control type is adopted as the dimming method, the ACDC converter generates a DC output voltage, and a series circuit of a light source and a constant current circuit is connected to the output terminal of the ACDC converter, and the AC− What separated the DC conversion function from the output current control function was the mainstream. However, this conventional method has a problem in that the circuit becomes large-scale and power loss occurs in the constant current circuit.

  Therefore, the control circuit 1e of this embodiment changes the feedback gain according to the conduction angle θ. As a result, when the load current Io is controlled at a constant current with respect to instantaneous fluctuations in the value of the AC voltage Va, high responsiveness and stability are realized regardless of whether the light source 12 is fully lit or dimmed. The

  FIG. 3 is a static characteristic diagram showing the relationship between the on-duty Don of the switching element of the converter 1b (SS converter) and the load current Io. Here, for simplicity of explanation, if the switching period T1 is constant and the on-time is Ton, Don = Ton / T1. As shown in FIG. 3, the relationship of the load current Io with respect to the on-duty Don is a relationship represented by an exponential function. That is, the change amount ΔIo1 of the load current Io in a region where the on-duty Don is large (region where the dimming level is high) and the region where the on-duty Don is small (region where the dimming level is low) ), The change amount ΔIo2 of the load current Io has a relationship of ΔIo1> ΔIo2. That is, it is shown that the optimum feedback gain changes when the load current Io fluctuates.

  Then, control circuit 1e turns on the switching element of converter 1b at a predetermined cycle, and determines the control value of on-duty Don of the switching element so that the deviation between the detected current value and the target current value becomes small. The control circuit 1e generates a switching control signal Sb based on the control value of the on-duty Don, and outputs the switching control signal Sb to the drive circuit 1f. Drive circuit 1f increases or decreases the on-duty Don of the switching element of converter 1b in accordance with switching control signal Sb.

  Specifically, the control circuit 1e obtains a target current value and a feedback gain corresponding to the conduction angle θ read from the phase detection signal Sa. For example, the control circuit 1e includes a first lookup table in which the target current value is associated with each value over the entire range of the conduction angle θ, and a feedback gain associated with each value over the entire range of the conduction angle θ. 2 lookup tables are stored in advance. Then, the control circuit 1e obtains the target current value and the feedback gain corresponding to the conduction angle θ read from the phase detection signal Sa with reference to the first lookup table and the second lookup table.

In the present embodiment, the control value is a difference value (an increase value or a decrease value from the previous on-duty Don) of the current on-duty Don with respect to the previous on-duty Don. The feedback gain is a coefficient used when the control value is obtained based on the deviation. In this embodiment, the control circuit 1e calculates | requires a control value with the digital PID control system which handles a discrete value. In this case, assuming that the sample number of the discrete value is n, the control value is Y (n), the feedback gains are α1, α2, and α3, and the deviation is E (n), the control circuit 1e obtains the following expression 1 To determine the control value Y (n). Y (n-1) is the previous control value, E (n) is the current deviation, E (n-1) is the previous deviation, and E (n-2) is the previous deviation. It is.
Y (n) = Y (n−1) + α1 × E (n) + α2 × E (n−1) + α3 × E (n−2) (Equation 1)
The feedback gains α1, α2, and α3 in Expression 1 are set to respective values corresponding to the conduction angle θ read from the phase detection signal Sa with reference to the second lookup table. Specifically, the smaller the conduction angle θ read from the phase detection signal Sa (the lower the dimming level instruction value), the larger the absolute values of the feedback gains α1, α2, and α3. Further, as the conduction angle θ read from the phase detection signal Sa is larger (as the dimming level instruction value is larger), the absolute values of the feedback gains α1, α2, and α3 are smaller.

  Therefore, the absolute values of the feedback gains α1, α2, and α3 increase as the dimming level decreases. As a result, the responsiveness and stability of the feedback control that changes the on-duty Don following the instantaneous fluctuation of the value of the AC voltage Va is improved, and the fluctuation of the load current Io can be suppressed.

  The effective value of the phase control voltage Vb decreases as the dimming level decreases, and the effective value of the phase control voltage Vb increases as the dimming level increases. However, since the control circuit 1e of the present embodiment obtains the control value Y (n) using the feedback gains α1, α2, and α3 corresponding to the conduction angle θ read from the phase detection signal Sa, the effective value of the phase control voltage Vb is obtained. Regardless of the fluctuation of the value, the responsiveness and stability of the feedback control can be maintained.

  That is, the lighting system 11 can reduce the flicker of light emitted from the light source 12 even when the value of the input voltage (AC voltage Va) fluctuates instantaneously.

  The control circuit 1e may store in advance a first function for obtaining a target current value with the conduction angle θ as a variable, and a second function for obtaining a feedback gain with the conduction angle θ as a variable. In this case, the control circuit 1e substitutes the conduction angle θ read from the phase detection signal Sa into the first function and the second function, respectively, and obtains the target current value and the feedback gains α1, α2, and α3.

  4 and 5 show gain characteristics and phase characteristics when the converter 1b includes a SEPIC circuit and an RC smoothing circuit. The RC smoothing circuit has a resistor and a capacitor.

  In FIG. 4, the maximum level (100% full lighting state) is instructed as the dimming level, and FIG. 4 shows each characteristic when the effective value of the phase control voltage Vb is 100V. The upper part of FIG. 4 shows gain characteristics Y11-Y14, and the lower part of FIG. 4 shows phase characteristics Y21-Y24. The gain characteristic Y11 and the phase characteristic Y21 are the characteristics of the single SEPIC circuit, and the gain characteristic Y12 and the phase characteristic Y22 are the characteristics of the digital PID control executed by the control circuit 1e. The gain characteristic Y13 and the phase characteristic Y23 are each characteristic of the RC smoothing circuit alone, the gain characteristic Y14 is a gain characteristic obtained by synthesizing the above-described gain characteristics Y11-Y13, and the phase characteristic Y24 is the above-described phase characteristic. This is a phase characteristic obtained by synthesizing Y21-Y23. Further, Y15 indicates a gain margin, and Y25 indicates a phase margin.

  On the other hand, in FIG. 5, 10% dimming lighting (dimming lighting state) is instructed as the dimming level, and FIG. 5 shows each characteristic when the effective value of the phase control voltage Vb is 50V. The upper part of FIG. 5 shows gain characteristics Y31-Y34, and the lower part of FIG. 5 shows phase characteristics Y41-Y44. The gain characteristic Y31 and the phase characteristic Y41 are the characteristics of the SEPIC circuit alone, and the gain characteristic Y32 and the phase characteristic Y42 are the characteristics of the digital PID control executed by the control circuit 1e. The gain characteristic Y33 and the phase characteristic Y43 are each characteristic of the RC smoothing circuit alone, the gain characteristic Y34 is a gain characteristic obtained by combining the above-described gain characteristics Y31-Y33, and the phase characteristic Y44 is the above-described phase characteristic. This is a phase characteristic obtained by synthesizing Y41-Y43. Furthermore, Y35 indicates a gain margin and Y45 indicates a phase margin.

  The control circuit 1e according to the present embodiment has feedback gains α1, α2, α2, α2 according to the dimming levels (parameters corresponding to the effective values of the load current Io and the phase control voltage Vb) in each of the full lighting state and the dimming lighting state. Change α3. As a result, as shown in FIGS. 4 and 5, the gain characteristics in the all lighting state and the gain characteristics in the dimming lighting state are substantially the same, and high responsiveness is realized regardless of the lighting state of the light source 12. . Moreover, a sufficient phase margin is ensured, and high stability is realized.

  Even in the dimming lighting state other than that in FIG. 5, responsiveness and stability can be ensured by changing the feedback gains α1, α2, and α3 according to the dimming level.

  If the feedback gain is not changed in accordance with the dimming level, the feedback gain corresponding to the characteristics of the single SEPIC circuit decreases if the effective value of the phase control voltage Vb decreases, and the light source 12 is in the dimming lighting state. It also goes down by controlling. If the feedback gain is not changed according to the dimming level, the phase margin at the time of dimming lighting decreases. As a result, high responsiveness and stability as in the present embodiment cannot be ensured.

  In the present embodiment, the control circuit 1e executes the digital PID control, but other control than the digital PID control may be executed.

(First modification)
FIG. 6 shows a first modification of the lighting system 11.

  Since the load current Io decreases as the dimming level decreases, the noise tolerance of the current detection signal Sd in FIG. 1 decreases as the dimming level decreases. For example, when the light source 12 is in the dimming lighting state of 1%, the voltage value of the current detection signal Sd is 1/100 compared to the voltage value of the current detection signal Sd in the 100% full lighting state. .

  Therefore, the lighting system 11 of the first modified example further includes an offset circuit 1m. The offset circuit 1m offsets the magnitude of the current detection signal Sd in the direction in which the detection current value increases. Then, the control circuit 1e obtains a detected current value based on the offset current detection signal Sd.

  Specifically, the offset circuit 1m further generates a current detection signal Sd that is offset in the direction in which the voltage value increases by further flowing a direct current of a predetermined value through the current detection circuit 1j, thereby reducing the noise resistance of the current detection signal Sd. It is improving. Here, in order to reduce the power loss in the offset circuit 1m and to reduce the electrical stress applied to the control circuit 1e, the offset circuit 1m uses the first control voltage Vd1 or the second control voltage Vd2 as a power source, It is preferable to generate a direct current to be supplied to the detection circuit 1j. In FIG. 6, the power supply of the offset circuit 1m is the second control voltage Vd2.

(Second modification)
FIG. 7 shows a second modification of the lighting system 11.

  As described above, since the load current Io decreases as the dimming level decreases, the noise resistance of the current detection signal Sd in FIG. 1 decreases as the dimming level decreases.

  Therefore, the lighting system 11 of the second modified example further includes a deviation amplifier circuit 1n. The deviation amplifier circuit 1n can improve the noise tolerance regardless of the lighting state by amplifying the deviation between the target current value and the detected current value.

  Specifically, the control circuit 1e outputs a DC voltage having a magnitude corresponding to the target current value to the deviation amplifier circuit 1n as the current target signal Sf. The deviation amplifying circuit 1n amplifies a differential voltage between the voltage value of the current target signal Sf and the voltage value of the current detection signal Sd, and outputs it as a deviation signal Sg to the control circuit 1e. And the control circuit 1e calculates | requires a deviation based on the voltage value of deviation signal Sg. The larger the voltage value of the deviation signal Sg, the larger the deviation, and the smaller the voltage value of the deviation signal Sg, the smaller the deviation.

  Each of the plurality of solid state light emitting elements included in the light source 12 is not limited to the LED, but may be other solid state light emitting elements such as an organic EL (Organic Electro Luminescence, OEL) or an inorganic EL. Further, the number of solid state light emitting elements is not limited to a plurality, and may be one. The electrical connection relationship of the plurality of solid state light emitting elements may be either serial connection or parallel connection, or may be a connection relationship combining series connection and parallel connection.

(Third Modification)
FIG. 8 shows a part of the configuration of the third modification of the lighting system 11. The lighting system 11 of the third modified example further includes a load voltage detection circuit 1p. In addition, the same code | symbol is attached | subjected to the structure similar to the above-mentioned embodiment, a 1st modification, or a 2nd modification, and description is abbreviate | omitted.

  Converter 1b (see FIGS. 1, 6, and 7) is an SS converter having a power factor improvement function, and can improve the power factor of the electric power supplied from AC power supply 9. Converter 1b includes a switching element, and realizes a power factor correction function by a switching operation for turning on and off the switching element.

  Control circuit 1e turns on the switching element of converter 1b at a predetermined cycle. Then, the control circuit 1e acquires the voltage value of the current detection signal Sd as the detected current value, and controls the on-duty Don (see FIG. 3) of the switching element so that the deviation between the detected current value and the target current value becomes small. Determine the value. The control circuit 1e generates a switching control signal Sb based on the control value of the on-duty Don, and outputs the switching control signal Sb to the drive circuit 1f. Drive circuit 1f increases or decreases the on-duty Don of the switching element of converter 1b in accordance with switching control signal Sb.

  Here, a ripple current having a frequency twice the frequency (50 Hz or 60 Hz) of the AC power supply 9 is superimposed on the load current Io. As a result, the voltage value of the current detection signal Sd also pulsates at the frequency of the AC power supply 9. Therefore, it is conceivable to smooth the current detection signal Sd. However, using the smoothed current detection signal may change the above-described phase margin. That is, the phase margin when the smoothed current detection signal is used is smaller than the phase margin when the non-smoothed current detection signal Sd is used, and the control stability with respect to the load current Io may be reduced. There is sex. In addition, the smoothed current detection signal has a slower response to the ripple component than the unsmoothed current detection signal Sd.

  A lighting system using a conventional analog control IC or the like has been designed with the idea that the average value of the on-time of the switching element of the SS converter should be a substantially fixed value. In this case, when the value of the AC voltage input to the SS converter fluctuates instantaneously due to disturbance or noise, the load current also fluctuates. For example, in FIG. 9, a missing waveform 30 occurs in the pulsating voltage Vc due to disturbance or noise. In addition, the conduction angle θ of the pulsating voltage Vc or the amplitude Vp of the pulsating voltage Vc may fluctuate due to disturbance or noise. As a result, the amount of light emitted from the light source may fluctuate due to instantaneous fluctuations in the value of the input AC voltage, causing light flickering. The degree of flicker varies depending on the smoothness of the output voltage or the dimming level. In particular, in a lighting system that employs a phase control system as a dimming system and has a converter having a power factor correction function, light flickering appears remarkably.

  In the above-described embodiment, the first modified example, and the second modified example, the lower the dimming level instruction value, the larger the absolute value of the feedback gain and the faster the feedback control response (the larger the phase margin). By doing so, the flicker of light is reduced. In this case, it is necessary to set a feedback gain value that can avoid flicker according to the instruction value of the light control level. However, when the lighting system 11 is a multi-load type system in which each of a plurality of light sources having different forward voltage characteristics can be used as the light source 12, flicker can be avoided by the forward voltage characteristics of the light source 12. Different feedback gain values.

  Therefore, in the third modification, the lighting system 11 includes a load voltage detection circuit 1p. The load voltage detection circuit 1 p has a series circuit of resistors 121 and 122, and the series circuit of the resistors 121 and 122 is connected to the light source 12 in parallel. The voltage between the connection point of the resistors 121 and 122 and the ground (the negative electrode of the capacitor 1c) is output to the control circuit 1e as the load voltage detection signal Sh. In this case, if the voltage across the light source 12 is the load voltage Vf, the load voltage detection signal Sh becomes a voltage signal having a voltage value proportional to the magnitude of the load voltage Vf, and the voltage value of the load voltage detection signal Sh is the load voltage. Corresponds to the value. That is, the load voltage value represents the magnitude of the load voltage Vf based on the load voltage detection signal Sh.

  The control circuit 1e obtains a target current value and a feedback gain corresponding to the conduction angle θ read from the phase detection signal Sa, as in the above-described embodiment, first modification, or second modification. In the following description, the feedback gain corresponding to the conduction angle θ is referred to as a first feedback gain.

  Further, the control circuit 1e reads the load voltage value based on the load voltage detection signal Sh and corrects the first feedback gain according to the load voltage value to obtain the second feedback gain.

  For example, the control circuit 1e stores in advance a third look-up table in which correction coefficients of a plurality of light sources that can be used as the light source 12 are associated with a plurality of ranges of load voltage values. Then, the control circuit 1e obtains a correction coefficient corresponding to the load voltage value read from the load voltage detection signal Sh with reference to the third lookup table.

For example, the control circuit 1e obtains first feedback gains α1, α2, and α3 (see Equation 1) corresponding to the conduction angle θ. Further, the control circuit 1e obtains correction coefficients K1, K2, and K3 corresponding to the load voltage value. And the control circuit 1e calculates | requires 2nd feedback gain (beta) 1, (beta) 2, and (beta) 3 using the following formula | equation 2, respectively.
β1 = K1 × α1, β2 = K2 × α2, β3 = K3 × α3 (Equation 2)
And the control circuit 1e calculates | requires control value Y (n) using the following formula | equation 3. FIG.
Y (n) = Y (n−1) + β1 × E (n) + β2 × E (n−1) + β3 × E (n−2) (Equation 3)
The second feedback gains β1, β2, and β3 in Equation 2 and Equation 3 are set to values corresponding to the conduction angle θ read from the phase detection signal Sa and the load voltage value read from the load voltage detection signal Sh. . Specifically, the second feedback gains β1, β2, and β3 are values obtained by correcting the first feedback gains α1, α2, and α3 corresponding to the conduction angle θ by the correction coefficients K1, K2, and K3 corresponding to the load voltage values, respectively. It is. The smaller the load voltage value read from the load voltage detection signal Sh (the smaller the value of the load voltage Vf), the larger the correction coefficients K1, K2, and K3. Further, the larger the load voltage value read from the load voltage detection signal Sh (the larger the value of the load voltage Vf), the smaller the correction coefficients K1, K2, and K3.

  Therefore, the absolute values of the second feedback gains β1, β2, and β3 increase as the value of the load voltage Vf decreases. As a result, the responsiveness and stability of the feedback control that changes the on-duty Don following the instantaneous fluctuation of the value of the AC voltage Va is improved, and the fluctuation of the load current Io can be suppressed.

  That is, even in the multi-load type lighting system 11 in which each of a plurality of light sources can be used as the light source 12, a feedback gain can be set according to the characteristics of the forward voltage of the light source used as the light source 12. . As a result, the flicker of light emitted from the light source 12 can be reduced regardless of the forward voltage characteristics of the light source used as the light source 12.

  Further, the control circuit 1e may store in advance a third function for obtaining a feedback gain using the conduction angle θ and the load voltage value as variables. In this case, the control circuit 1e substitutes the conduction angle θ read from the phase detection signal Sa and the load voltage value read from the load voltage detection signal Sh into the third function, respectively, to thereby obtain the second feedback gains β1, β2, β3. For each.

  Further, the load voltage detection circuit 1p may have the configuration shown in FIG. The load voltage detection circuit 1p in FIG. 10 includes an operational amplifier 123, a resistor 124, and a capacitor 125 in addition to the resistors 121 and 122. The operational amplifier 123 operates as a non-inverting amplifier, with the voltage between the connection point of the resistors 121 and 122 and the ground (the negative electrode of the capacitor 1c) being input to the non-inverting input terminal and the reference voltage Vd3 being input to the inverting input terminal. . The output of the operational amplifier 123 is smoothed by the RC circuit of the resistor 124 and the capacitor 125, and the voltage across the capacitor 125 is output as the load voltage detection signal Sh. In FIG. 10, illustration of elements such as resistors for determining the gain as the non-inverting amplifier is omitted.

  FIG. 11A shows a luminaire B1 that is a downlight embedded in the ceiling panel 5. The luminaire B1 includes the lighting system 11 described above, the light source 12 described above, and housings 31 and 32. The housing 31 is formed in a bottomed cylindrical shape whose upper surface is closed by a metal such as aluminum and whose lower surface is opened. The casing 31 supports the light source 12, and the light source 12 is attached to the upper bottom surface of the casing 31. The light source 12 has a plurality of LEDs mounted on a substrate. Further, the lower surface opening of the housing 31 is closed by a disc-shaped cover 33. The cover 33 is made of a translucent material such as glass or polycarbonate. The lighting system 11 is housed in a metal housing 32 formed in a rectangular box shape, supported by the housing 32, and disposed on the upper surface of the ceiling panel 5. The lighting system 11 is electrically connected to the light source 12 via an electric cable 41 and a connector 42.

  FIG. 11B shows a lighting fixture B <b> 2 that is another downlight that is embedded in the ceiling panel 5. The lighting fixture B2 includes the lighting system 11 described above, the light source 12 described above, and a housing 61. The housing 61 is formed in a bottomed cylindrical shape whose upper surface is closed by a metal such as aluminum and whose lower surface is opened. The lower surface opening of the housing 61 is closed by a disk-shaped cover 62. The cover 62 is made of a translucent material such as glass or polycarbonate. The inside of the housing 61 is divided into upper and lower portions by a disk-shaped partition plate 63. The lighting system 11 is arranged on the upper surface side of the partition plate 63, and the casing 61 supports the lighting system 11. A light source 12 is disposed on the lower surface of the partition plate 63. The lighting system 11 is electrically connected to the light source 12 by an electric cable 71 passing through the through hole 64 of the partition plate 63.

  Since each of the lighting fixtures B1 and B2 includes the lighting system 11 described above, flickering of light emitted from the light source 12 can be reduced even when the value of the input voltage (AC voltage Va) fluctuates instantaneously.

  As described above, the lighting system 11 of the first aspect according to the embodiment includes the power supply circuit 110, the current detection circuit 1j, and the control circuit 1e. The power supply circuit 110 is supplied with AC power from the AC power source 9 and supplies a DC load current Io to the light source 12 by controlling the on-duty of the switching element. The current detection circuit 1j outputs a current detection signal Sd corresponding to the magnitude of the load current Io. The control circuit 1e sets a target current value of the load current Io according to the instruction value of the light control level of the light source 12. Further, the control circuit 1e sets the difference between the detected current value indicating the magnitude of the load current Io based on the current detection signal Sd and the target current value as a deviation. Then, the control circuit 1e multiplies the deviation by feedback gains α1, α2, α3 or β1, β2, β3 to obtain the control value of the on-duty Don of the switching element for reducing the deviation, and based on the control value To adjust the on-duty Don. The control circuit 1e sets feedback gains α1, α2, α3 or β1, β2, β3 according to the instruction value of the dimming level.

  The lighting system 11 described above can reduce the flicker of light emitted from the light source 12 even when the value of the input voltage (AC voltage Va) fluctuates instantaneously.

  Moreover, the lighting system 11 of the 2nd aspect which concerns on embodiment is further provided with the load voltage detection circuit 1p which detects the magnitude | size of the both-ends voltage (load voltage Vf) of the light source 12 as a load voltage value in a 1st aspect. It is preferable. It is preferable that the control circuit 1e sets the feedback gains β1, β2, and β3 according to the dimming level instruction value and the load voltage value.

  The lighting system 11 described above can set feedback gains β1, β2, and β3 according to the forward voltage characteristics of the light source 12. As a result, the flickering of the light emitted from the light source 12 can be reduced regardless of the forward voltage characteristics of the light source 12.

  Further, in the lighting system 11 of the third aspect according to the embodiment, in the second aspect, the control circuit 1e increases the absolute values of the feedback gains β1, β2, and β3 as the instruction value of the dimming level is lower. Further, it is preferable to increase the absolute values of the feedback gains β1, β2, and β3 as the load voltage value is lower.

  The lighting system 11 described above can reduce flickering of light emitted from the light source 12 regardless of the forward voltage characteristics of the light source 12.

  Further, the lighting system 11 of the fourth aspect according to the embodiment is the offset circuit that offsets the magnitude of the current detection signal Sd in a direction in which the detection current value increases in any one of the first to third aspects. It is preferable to further include 1 m. The control circuit 1e obtains a detected current value based on the offset current detection signal Sd.

  The lighting system 11 described above can improve noise resistance of the current detection signal Sd.

  The lighting system 11 of the fifth aspect according to the embodiment is the difference between the voltage value corresponding to the detected current value and the voltage value corresponding to the target current value in any one of the first to fourth aspects. Is preferably further provided with a deviation amplifying circuit 1n that outputs the deviation signal Sg as a deviation signal Sg. The control circuit 1e calculates the deviation based on the deviation signal Sg.

  The lighting system 11 described above can improve noise resistance regardless of the lighting state.

  Further, in the lighting system 11 of the sixth aspect according to the embodiment, in any one of the first to fifth aspects, the power supply circuit 110 has a power factor improvement function for improving the power factor of the AC power supply 9. It is preferable.

  When the above-described lighting system 11 includes the power supply circuit 110 having the power factor correction function, even if the value of the input voltage (AC voltage Va) fluctuates instantaneously, flickering of light emitted from the light source 12 is reduced. Can do.

  In addition, in the lighting system 11 of the seventh aspect according to the embodiment, in any one of the first to sixth aspects, the control circuit 1e increases the target current value as the dimming level instruction value is higher. In addition, it is preferable to reduce the feedback gain. The control circuit 1e preferably decreases the target current value and increases the feedback gain as the dimming level instruction value is lower.

  The lighting system 11 described above can set a feedback gain according to the instruction value of the dimming level, and reduces flickering of light emitted from the light source 12 even when the value of the input voltage (AC voltage Va) fluctuates instantaneously. be able to.

  The lighting system 11 of the eighth aspect according to the embodiment is the phase detection circuit 1d (information) that receives the instruction information representing the instruction value of the dimming level from the outside in any one of the first to seventh aspects. It is preferable to further include an acquisition unit. The power supply circuit 110 receives an AC phase control voltage Vb in which the conduction angle θ, which is the energization period of the AC voltage Va of the AC power supply 9, is variably set. The phase detection circuit 1d receives the conduction angle θ as instruction information, and transmits a dimming level instruction value to the control circuit 1e.

  The lighting system 11 described above can reduce flickering of light emitted from the light source 12 even when a phase control method for controlling the phase of the AC voltage is adopted as the dimming method.

  Moreover, the lighting device 1 of the ninth aspect according to the embodiment includes the lighting system 11 according to any one of the first to eighth aspects, and the light source 12 to which the load current Io is supplied from the lighting system 11. Prepare.

  The lighting device 1 described above can reduce flickering of light emitted from the light source 12 even when the value of the input voltage (AC voltage Va) fluctuates instantaneously.

  Moreover, lighting fixture B1, B2 of the 10th aspect which concerns on embodiment is the lighting system 11 as described in any one of 1st thru | or 8th, and the light source 12 to which the load current Io is supplied from the lighting system 11. And housings 31, 32, 61 on which at least the light source 12 is supported.

  The lighting fixtures B1 and B2 described above can reduce the flicker of light emitted from the light source 12 even when the value of the input voltage (AC voltage Va) fluctuates instantaneously.

  Moreover, the above-mentioned embodiment and modification are examples. For this reason, the present invention is not limited to the above-described embodiments and modifications, and any design other than these embodiments and modifications may be used as long as it does not depart from the technical idea of the present invention. Of course, various changes can be made according to the above.

DESCRIPTION OF SYMBOLS 1 Illuminating device 11 Lighting system 12 Light source 110 Power supply circuit 1d Phase detection circuit (information acquisition part)
1e Control circuit 1j Current detection circuit 1m Offset circuit 1n Deviation amplification circuit 1p Load voltage detection circuit 31, 32, 61 Case 9 AC power supply B1, B2 Lighting fixture Va AC voltage Vf Load voltage Io Load current Sd Current detection signal Sg Deviation signal Don On-duty α1, α2, α3 Feedback gain β1, β2, β3 Feedback gain θ Conduction angle

Claims (10)

A power supply circuit that is supplied with AC power from an AC power supply and that controls the on-duty of the switching element to supply a DC load current to the light source;
A current detection circuit that outputs a current detection signal according to the magnitude of the load current;
A target current value of the load current is set according to an indication value of the light control level of the light source, and a difference between the detected current value indicating the magnitude of the load current based on the current detection signal and the target current value is deviated. A control circuit for obtaining a control value of the on-duty of the switching element for reducing the deviation by multiplying the deviation by a feedback gain, and adjusting the on-duty based on the control value; Prepared,
The control circuit sets the feedback gain according to the instruction value of the dimming level. A load voltage detection circuit that detects the magnitude of the voltage across the light source as a load voltage value;
The lighting system according to claim 1, wherein the control circuit sets the feedback gain according to the indication value of the dimming level and the load voltage value. The lighting circuit according to claim 2, wherein the control circuit increases the absolute value of the feedback gain as the indicated value of the dimming level is lower, and increases the absolute value of the feedback gain as the load voltage value is lower. system. An offset circuit for offsetting the magnitude of the current detection signal in a direction in which the detection current value increases;
The lighting system according to any one of claims 1 to 3, wherein the control circuit obtains the detected current value based on the offset current detection signal. A deviation amplifying circuit for amplifying a difference between a voltage value corresponding to the detected current value and a voltage value corresponding to the target current value, and outputting as a deviation signal;
The lighting system according to any one of claims 1 to 4, wherein the control circuit obtains the deviation based on the deviation signal. The lighting system according to any one of claims 1 to 5, wherein the power supply circuit has a power factor improvement function for improving a power factor of the AC power supply. The control circuit increases the target current value as the indicated value of the dimming level is higher, and decreases the feedback gain, decreases the target current value as the indicated value of the dimming level is lower, and The lighting system according to any one of claims 1 to 6, wherein the feedback gain is increased. An information acquisition unit for receiving instruction information representing an instruction value of the dimming level from the outside;
The power supply circuit receives an AC phase control voltage in which a conduction angle that is an energization period of the AC voltage of the AC power supply is variably set,
The lighting system according to any one of claims 1 to 7, wherein the information acquisition unit receives the conduction angle as the instruction information and transmits an instruction value of the dimming level to the control circuit. A lighting system according to any one of claims 1 to 8,
A light source that is supplied with the load current from the lighting system. A lighting system according to any one of claims 1 to 8,
A light source supplied with the load current from the lighting system;
A housing that supports at least the light source.

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