JP6157247B2 - LED dimming control device - Google Patents

Description

  The present invention relates to an LED dimming control device.

  The LED dimming control device is a device that controls dimming of an LED (Light Emitting Diode), and is a control circuit in the LED dimming device provided in the LED lighting device. Even when the LED lighting device is connected to a dimming circuit using a thyristor that has been used in a conventional incandescent lamp, it is desirable to realize a dimming mode similar to that of the incandescent lamp using the thyristor dimming circuit. It is.

  However, the dimming circuit of the thyristor adjusts the average current by phase-controlling the voltage waveform of the AC power supply, whereas the dimming control of the LED is performed by controlling the duty ratio of a constant pulse signal. Therefore, between the dimming circuit for the incandescent lamp and the LED, a rectifier that converts the AC drive voltage phase-controlled by the dimming circuit for the incandescent lamp into a DC drive voltage, and a voltage waveform of the DC drive voltage. There is provided an LED dimming control device that detects the phase control performed in the dimming circuit based on this and generates a pulse signal subjected to pulse width modulation (PWM) suitable for the dimming control of the LED.

  The LED dimming control is described in the following patent documents.

JP 2007-35403 A JP 2011-198671 A JP 2009-26544 A

  The conventional LED dimming control device detects the conduction angle at which the thyristor is conducting by phase control from the output waveform of the thyristor dimming circuit, and generates a PWM pulse signal based on the detected conduction angle.

  However, the dimming control of the incandescent lamp controlled by the dimmer circuit of the thyristor is a control that depends not only on the conduction angle but also on the amplitude voltage and frequency of the commercial AC power supply. Therefore, in order to perform dimming control equivalent to an incandescent lamp, dimming control that depends on the amplitude voltage and frequency of the commercial AC power supply in addition to the conduction angle is required.

  On the other hand, commercial AC power supplies in developing countries may not have high frequency and amplitude voltage quality, and cannot be predicted uniformly. Therefore, it is desired to control the PWM pulse signal of the LED by accurately detecting the amplitude voltage, frequency, and conduction angle of the commercial AC power supply from the waveform of the output voltage of the dimmer circuit of the thyristor.

  Accordingly, an object of the present invention is to provide an LED dimming control device that generates an appropriate PWM pulse by detecting at least an amplitude voltage of an AC power source, a frequency, and a conduction angle with high accuracy.

A first aspect of the embodiment is an LED dimming control device for controlling dimming of an LED, which is supplied with the output voltage from a dimmer that inputs an AC voltage and outputs an output voltage that is phase-controlled.
A waveform information detection circuit for detecting a voltage of the output voltage in an off period in which the dimmer is turned off, and detecting an amplitude voltage of the AC voltage based on the detected voltage in the off period;
And a drive control circuit for generating a drive pulse for driving and controlling the LED based on the amplitude voltage.

  According to the first aspect, the amplitude voltage of the AC voltage can be detected with high accuracy.

It is a figure which shows the structure of a light controller, an incandescent lamp, and LED lighting fixture. It is a figure which shows the circuit example of a light controller. It is a figure which shows the structural example 1 of the LED lighting fixture in this Embodiment. It is a figure which shows the structural example 2 of the LED lighting fixture in this Embodiment. It is a figure which shows the example of the LED drive pulse PWM1 corresponding to the output voltage of the dimmer, its rectified rectified output voltage, and it. It is a figure which shows the voltage waveform in the node a input into LED dimming control apparatus 40, an AC power supply voltage waveform, and the detected waveform information. It is a detailed view of the voltage waveform (solid line) of node a and the AC power supply voltage waveform (broken line). It is a figure which shows the example of a table set to the PWM control circuit 42 of the LED dimming control apparatus 40 in this Embodiment. It is a figure explaining the drawing current which the current drawing circuit should flow. 4 is a configuration diagram of a waveform information detection circuit 41. FIG. It is a flowchart figure of a waveform information detection method. It is a flowchart figure which shows the detection method (1) of the amplitude voltage A in this Embodiment. It is a flowchart figure which shows an example of the detection method (2) of the amplitude voltage A in this Embodiment. It is a flowchart figure which shows another example of the detection method (2) of the amplitude voltage A in this Embodiment. It is a flowchart figure which shows another example of the detection method (2) of the amplitude voltage A in this Embodiment. It is a flowchart figure which shows another example of the detection method (2) of the amplitude voltage A in this Embodiment. It is a flowchart figure which shows another example of the detection method (2) of the amplitude voltage A in this Embodiment.

  FIG. 1 is a diagram showing a configuration of a dimmer, an incandescent lamp, and an LED lighting apparatus. FIG. 1A shows the configuration of a commercial AC power source, a dimmer 10, and an incandescent lamp 12. Usually, in a residential facility or the like, a triac dimmer 10 is provided between a commercial AC power source and the incandescent lamp 12. The dimmer 10 is generally provided inside the wall of the room. The brightness of the incandescent lamp 12 can be adjusted by adjusting a dimming knob (not shown) of the dimmer 10.

  FIG. 1B shows a configuration of a commercial AC power source, a dimmer 10, and an LED lighting apparatus 20. When the LED lighting fixture 20 is attached to the power supply terminals N1 and N2 of the room where the commercial AC power source and the dimmer 10 shown in FIG. 1A are provided and the dimming knob of the dimmer 10 is operated, Similarly, the brightness of the LED illumination can be adjusted.

  FIG. 2 is a diagram illustrating a circuit example of the dimmer. The dimmer includes a triac TR, a bidirectional diode D1, a variable resistor Rv whose resistance is adjusted by a dimming knob, and a capacitor C0. The bidirectional diode D1, the variable resistor Rv whose resistance is adjusted by the dimming knob, and the capacitor C0 form a diac that generates a gate pulse to the triac TR. The load RL is the incandescent lamp 12 in the case of FIG. 1 (A), and the LED lighting fixture 20 in the case of FIG. 1 (B).

  In the triac TR, when the voltage of the node NT rises while the voltage of the AC power supply is applied from the top to the bottom in FIG. 2 and a positive gate pulse is applied from the diac to the triac TR, the triac TR becomes conductive. Then, the current flows from the top to the bottom, and the conduction state is continued until the voltage is less than the forward voltage of the triac TR or less than the minimum conduction current. On the other hand, when the voltage of the node NT drops while the AC power supply voltage is applied from the bottom to the top of FIG. 2 and a negative gate pulse is applied from the diac to the triac TR, the triac TR becomes conductive. Then, current flows from the bottom to the top, and continues until it becomes less than the forward voltage of the triac TR or less than the minimum conduction current.

  Since AC power that is a sine wave is applied, the timing at which the gate pulse is applied changes according to the resistance value of the variable resistor Rv, and the period during which the triac is turned on changes. Therefore, the dimmer 10 variably controls the resistance value of the variable resistor Rv with the dimming knob, variably controls the timing at which the triac is turned on accordingly, and applies the voltage obtained by phase-controlling the AC power source to the load RL. ing. Detailed operation will be described later.

  3 and 4 are diagrams showing configuration examples 1 and 2 of the LED lighting apparatus in the present embodiment. In the configuration example 1 of FIG. 3, the LED lighting apparatus 20 includes a full-wave rectifier circuit 31 connected to the output terminals N1 and N2 from the dimmer 10, an LED dimming control device 40, a current extraction circuit 32, It has a current control circuit 33, a transformer 34, an LED, a diode 35, and a capacitor 36.

  As described above, the AC voltage of the commercial AC power supply is phase-controlled by the dimmer 10 and converted to a DC voltage by the full-wave rectifier circuit 31. The current drawing circuit 32 is a circuit that draws a current from the node a in order to supply a minimum current necessary for the triac in the dimmer 10 to maintain a conductive state, and is a MOS transistor, for example. The current control circuit 33 is a circuit that supplies a drive current to the LED via the transformer 34, and is, for example, a MOS transistor.

  The LED dimming control device 40 receives a rectified output voltage obtained by rectifying the output voltage of the dimmer 10 by the rectifier circuit 31 from the node a, and detects a waveform information of the rectified output voltage. , And a PWM control circuit (drive control circuit) 42 that generates an LED drive pulse PWM1 for LED drive current control and an extraction drive pulse PWM2 for current extraction control based on the detected waveform information. In the present embodiment, the PWM control circuit 42 generates drive pulses PWM1 and PWM2 that are pulse width modulated in accordance with the respective required current amounts.

  In the configuration example 1 of FIG. 3, since the drive current generated by the current control circuit 33 flows to the LED through the transformer 34, the insulation type drive in which the voltage on the AC power supply side and the voltage on the LED side are separated by the transformer 34. Circuit.

  In the configuration example 2 of FIG. 4, the LED lighting apparatus 20 includes a full-wave rectifier circuit 31, an LED dimming control device 40, a current extraction circuit 32, a current control circuit 33, an LED, a capacitor 36, and an LED dimming device. And a light control device 40. Up to this point, the configuration is the same as that of the configuration example 1 in FIG. In the configuration example 2 of FIG. 4, the inductor L1, the diode 37, and the current control circuit 33 constitute a step-down circuit, the rectified output voltage of the node a is lowered to a constant voltage by the step-down circuit, and the LED drive pulse PWM1 A current corresponding to the duty ratio is supplied to the LED.

  Specifically, when the current control circuit 33 is turned on by the LED drive pulse PWM1, current flows from the node a through the path of the inductors L1, LED and the current control circuit 33, energy is accumulated in the inductor L1, and the LED drive pulse PWM1 When the current control circuit 33 becomes non-conductive, the current of the inductor L1 flows through the path of the LED, the diode 37, and the inductor L1. The voltage applied to the LED by the capacitor 36 is maintained at a desired voltage.

  In the configuration example 2 of FIG. 4, the voltage on the AC power supply side and the voltage on the LED side are stepped down without being separated, so that it is a non-insulated insulated step-down type drive circuit.

  3 and 4, the current control circuit 33 and the current extraction circuit 32 are provided separately. However, the current control circuit 33 performs the triac current extraction function by the current extraction circuit 32. You can also. In that case, only the MOS transistor of the current control circuit 33 is provided.

  FIG. 5 is a diagram illustrating an example of the output voltage of the dimmer, the rectified rectified output voltage, and the LED drive pulse PWM1 corresponding thereto. (1-1) of FIG. 5 shows the waveform of the output voltage when dimming control is performed so that the triac of the dimmer 10 is always turned on. In this case, since the conduction voltage of the triac is very small, the voltage of the AC power source is almost the same as the output voltage of the dimmer 10. (2-1) in FIG. 5 is a waveform of the rectified output voltage at the node a in which the output voltage of (1-1) is rectified by the rectifier circuit 31, and is converted from alternating current to direct current.

  (1-2) in FIG. 5 shows the waveform of the output voltage when dimming control is performed so that the TRIAC of the dimmer 10 conducts at about 45 ° and 225 °. In this case, the output voltage suddenly rises when the triac is turned on by the trigger pulse, and the triac is turned off near the next zero cross. Therefore, generally, the range of the phase angle from the rising edge (or falling edge) of the output voltage to the next zero cross is defined as the conduction angle. (2-2) in FIG. 5 is a waveform of the rectified output voltage at the node a where the output voltage of (1-2) is rectified by the rectifier circuit 31, and is converted from alternating current to direct current.

  As described above, it is not preferable to directly apply the rectified output voltages (2-1) and (2-2) to the LEDs. For example, since the frequency of a commercial AC power supply is 50 Hz or 60 Hz, when the rectified output voltage (2-1) (2-2) is directly applied to the LED, the human blinks the LED at a low frequency of about 50 Hz or 60 Hz. This is because flickering that can be felt occurs. This is because the commercial AC power supply may have a high amplitude voltage and may exceed the withstand voltage of the LED.

  Therefore, the LED dimming control device 40 in the LED lighting device 20 has the output voltage of (1-1) (2-1) in FIG. 5 or the rectified output voltage of (2-1) (2-2). The waveform is analyzed, and the conduction angle, period (or half period), and amplitude voltage are detected as the waveform information. Then, based on the detected conduction angle, period, and amplitude voltage, the LED dimming control corresponding to the dimming control performed by the dimmer 10 is performed based on the sine wave of the commercial AC power source and its phase control. An LED drive pulse PWM1 is generated. At the same time, the LED dimming control device 40 also generates an extraction drive pulse PWM2 for extracting current from the node a in order to maintain the minimum conduction current to be passed through the triac in the dimmer 10. The extraction drive pulse PWM2 is also generated so as to extract a desired current based on the detected conduction angle, period, and amplitude voltage.

  (3-1) and (3-2) in FIG. 5 are LED drive pulses PWM1 generated by the PWM control circuit 42 of the LED dimming control device 40 corresponding to the rectified output voltages (2-1) and (2-2). It is an example. The duty ratio of the LED drive pulse of (3-1) is larger than that of (3-2).

  FIG. 6 is a diagram illustrating a voltage waveform at the node a, an AC power supply voltage waveform, and detected waveform information input to the LED dimming control device 40. 6A, 6B, and 6C show an actual voltage waveform of the node a indicated by a thick line and an AC power supply voltage waveform indicated by a thin line.

  The thick line is a voltage waveform actually generated at the node a, whereas the thin line AC power supply voltage waveform is an ideal sine wave waveform, and is very small between T1 and T2 in the waveform of the node a. There is no significant increase, a peak at time T2, and a non-linear voltage drop between T2 and T3.

  On the other hand, the voltage waveform at the node a becomes zero cross Z1 at time T1, the triac of the dimmer becomes conductive at time T2, and a rising edge EG having a peak is generated, and becomes zero cross Z2 at time T3. As a result, the triac of the dimmer is conducted in the opposite direction and an edge rising in the opposite direction is generated, and further, at time T5, the zero cross Z3 is obtained again.

  Further, the voltage waveform of the node a is lower than the AC power supply voltage due to the voltage drop due to the resistor Rv of the dimmer 10 and the capacitor C0, although the triac of the dimmer has not been conducted yet during the time T1-T2. It is rising moderately. Then, when the voltage at the connection node NT of the variable resistor Rv and the capacitor C0 of the dimmer 10 in FIG. 2 rises depending on the resistance value of the variable resistor Rv and a trigger pulse is generated, the peak of the rectified output voltage is reached at time T2. A rising edge EG accompanied by Strictly speaking, the voltage waveform of the node “a” occurs between T2 and T3 and between T4 and T5, and a period in which the triac is conductive and a period in which the triac is less than the threshold voltage of the triac.

  FIG. 7 is a detailed diagram of the voltage waveform at node a (solid line) and the AC power supply voltage waveform (broken line). The triac TR is conductive from the rising edge EG of the node a to the phase angle θ2 that decreases to the voltage A2. While the triac is conducting, the voltage of the dimmer 10 in FIG. 2 becomes a relatively small conducting voltage of the triac, and a voltage obtained by subtracting the triac conducting voltage from the AC power supply voltage is applied to the load RL, that is, the node a. The condition for the transition of the triac from the conducting state to the non-conducting state is that the current flowing through the triac is less than the minimum conducting current, or the voltage applied to the triac is lower than the voltage for turning off (threshold voltage). It is to become. The conduction voltage of the triac changes with temperature and on-current and is non-linear.

  As described above, the condition for the TRIAC to transition from the conductive state to the non-conductive state is that the current flowing through the TRIAC is less than the minimum conductive current or the voltage applied to the TRIAC to turn off (threshold voltage). ) Is lower. Although the minimum conduction current is supplied by the current extraction circuit 32 described above, when the AC power supply voltage (broken line) decreases and the voltage at the node a (solid line) reaches the voltage A2, the voltage A3 applied to the triac is turned off. The triac TR is in a non-conducting state from the phase angle θ2 corresponding to the voltage A2 to the zero cross Z2. The voltage A2 can be found based on the voltage A3 corresponding to the voltage for turning off the triac.

  When the triac is turned off, the voltage of the dimmer 10 in FIG. 2 becomes the voltage of the resistor Rv and the capacitor C0, and the voltage of the connection node a with the load RL is adjusted with the AC power supply voltage and the load RL. The voltage is divided by the resistance Rv in the optical device 10 and the voltage of the capacitor C0. That is, the voltage of the node a is a voltage obtained by subtracting the voltage of the dimmer 10 from the AC power supply voltage. The voltage at the node a is 1 / K times the AC power supply voltage when the voltage dividing ratio between the dimmer 10 and the load RL is a ratio K. Since the voltage division ratio K is a constant value, the AC power supply voltage between the phase angle θ2 and the zero cross Z2 is K times the voltage at the node a.

  That is, while the triac from the rising edge EG to the phase angle θ2 in FIG. 7 is in a conducting state, the triac conducting voltage fluctuates, so it is difficult to accurately calculate the AC power supply voltage from the voltage at the node a. On the other hand, since the triac is off and the proportionality constant K is constant between the phase angle θ2 and the zero cross Z2, the AC power supply voltage can be accurately calculated from the voltage at the node a.

If the phase angle θ2 when the node a becomes the voltage A2 can be detected by using this, the amplitude voltage A of the AC power supply voltage can be obtained as follows.
A * sin (θ2) = K * A2
Therefore,
A = K * A2 / sin (θ2) (1)
A2 is a threshold voltage of triac, K is a known proportionality constant, and θ2 is a detected phase angle. Therefore, even if the AC power supply voltage supplied to the dimmer 10 is unknown, the amplitude voltage A of the AC power supply voltage can be calculated by the above formula.

  Therefore, the waveform information detection circuit 41 according to the present embodiment, for example, AD-converts the rectified output voltage of the node a and analyzes the change in the digital value of the voltage, first, as shown in FIG. In addition, the zero cross point Z1-Z3 and the rising edge EG are detected. As a result, a conduction interval t1 and a half cycle t0 are detected.

The half cycle t0 is f = 1 / (2 * t0) where frequency is f.
The phase angle range (conduction angle) θ1 of the conduction section t1 from the rising edge EG to the zero cross Z2 is
θ1 = (t1 / t0) * 180 °
become.

  Thereby, the waveform information detection circuit 41 can detect the conduction angle θ1 and the frequency f shown in FIG. 6C as waveform information. In addition, in the range of the phase angle of the conduction angle θ1, the period in which the triac is non-conducting is included. However, in general, in the conduction circuit of the dimming circuit, the period from the rising edge due to the trigger pulse to the next zero cross point is defined as the conduction angle. Adopt definition.

  Next, the waveform information detection circuit 41 of the present embodiment detects the amplitude voltage A of the AC power supply voltage. There are various detection methods. As an example, in the first embodiment described later, detection is performed as follows.

  That is, first, the timing at which the voltage waveform at the node a becomes the threshold voltage A2 is detected. The phase angle θ2 is calculated from the timing and the half-cycle period t0, and the amplitude voltage A of the AC power supply voltage is accurately calculated by the above-described equation (1).

  The output waveforms (1-1) and (1-2) of the dimmer 10 shown in FIG. 5 are different from the rectified output waveforms (2-1) and (2-2) of the node a in that the negative voltage is a positive voltage. Except for being rectified, the waveform is equivalent. Therefore, the waveform information detection circuit 41 may detect the waveform information from the output waveform of the dimmer 10 instead of the voltage waveform at the node a.

FIG. 8 is a diagram showing an example of a table set in the PWM control circuit 42 of the LED dimming control device 40 in the present embodiment. This table corresponds to the adjustment amount 100% to 0% of the dimmer 10, the conduction angle θ3 in the case of three types of AC power supplies, the duty ratio of the drive pulse PWM1 for the current control circuit, and the brightness of the LED illumination obtained. (%), The drawing current (mA) of the current drawing circuit. The three types of AC power sources are as follows.
(1) Left side: amplitude voltage 100V, frequency 50Hz
(2) Center: amplitude voltage 100V, frequency 60Hz
(3) Right side: amplitude voltage 220V, frequency 50Hz
This example table shows an example of LED dimming control, and there are various types depending on the idea of how to perform LED dimming control based on the output voltage or rectified output voltage of the dimmer 10. It becomes a number. The example of FIG. 7 will be described below.

[(1) Left: Amplitude voltage 100V, Frequency 50Hz]
First, (1) Left side: When the amplitude voltage is 100 V and the frequency is 50 Hz, the duty ratio 80% -0% of the LED drive pulse PWM1 to the current control circuit 33 is set for the conduction angle θ1 of 180 ° to 0 °. ing. The brightness of the LED illumination in this case is 100% to 0%. Further, the drawing current to be passed through the current drawing circuit 32 is set to 0 to 20 mA.

  FIG. 9 is a diagram for explaining a drawing current that the current drawing circuit 32 should flow. The horizontal axis is the brightness setting value, and the vertical axis is the current. The LED current increases from 0 with respect to the brightness setting value 0% -100% on the horizontal axis. On the other hand, the extraction current gradually increases when the brightness setting value becomes 25% or less. As a result, the total current of the LED current and the extraction current becomes the minimum current Imin when the brightness setting value is in the range of 0-25%. This minimum current Imin corresponds to the minimum conduction current required for the thyristor to maintain the conduction state. As described above, when the brightness setting value is sufficiently high and a large amount of LED current flows, no extraction current is necessary, and when the brightness setting value is low and the LED current becomes small, the extraction current is necessary.

  Returning to FIG. 8, (1) Left side: At an amplitude voltage of 100 V and a frequency of 50 Hz, the adjustment amount of the dimmer 100% -0% is associated with the conduction angle θ1 of 180 ° -0 °. However, in the example of FIG. 8, when the adjustment amount of the dimmer is 16% -0%, the conduction angle θ1 is 28.8 ° -0 °, but the duty ratio of the LED drive pulse PWM1 to the current control circuit is Is set to 0%, and the brightness of the illumination is also zero. The reason will be described in the case of the following (2) center: amplitude voltage 100 V, frequency 60 Hz.

  In the setting table of FIG. 8, (1) left side: conduction angle θ1, LED drive pulse performed for the dimming amount 100% -0% of the dimmer shown on the left side: amplitude voltage 100V and frequency 50Hz. The settings of PWM1 and extraction current are maintained even in (2) center: amplitude voltage 100 V, frequency 60 Hz, and (3) right side: amplitude voltage 220 V, frequency 50 Hz.

[(2) Center: Amplitude voltage 100V, Frequency 60Hz]
(2) Center: At an amplitude voltage of 100 V and a frequency of 60 Hz, the conduction angle θ1 is reduced from 180 ° -0 ° to -36 °. The reason is that the dimming amount of the dimmer is associated with the variable range of the variable resistor Rv in the triac circuit in the dimmer of FIG. 2, while the time until the triac starts to conduct is , The absolute time depending on the variable resistance Rv and the capacitance C0. In contrast, (1) the left side has a long period of 50 Hz, while (2) the center has a short period of 60 Hz. As a result, if the conduction angle θ1 is assigned to 180 ° −0 ° at 50 Hz on the left side with respect to the absolute time that is the light control amount of the dimmer, (2) the conduction angle θ1 at the center 60 Hz is It will decrease from 180 ° -0 ° to -36 °.

  Therefore, (2) at the center, the duty ratio of the LED drive pulse PWM1 is assigned to 80% to 0% with respect to the positive range of the conduction angle θ1. This is why (1) the duty ratio of the LED drive pulse PWM1 is set to 0% with respect to the conduction angle θ1 of 28.8 ° -0 ° in the case of 50 Hz on the left side.

  (2) Since the voltage of the AC power supply is 100 V at the center and (1) the same voltage as that on the left side, the duty ratio and the extraction current of the LED drive pulse PWM1 are the same as those on the left side of (2).

[(3) Right side: amplitude voltage 220V, frequency 50Hz]
(3) On the right side, the frequency is 50 Hz and (1) the same as the left side, so the conduction angle θ1 is also the same. However, since the amplitude voltage is as high as 220 V on the right side (3), correspondingly, (1) the duty ratio of the LED drive pulse PWM1 is 100/220 times smaller than that on the left side. As a result, however, the brightness of the illumination is (1) the same as the left side. On the right side (3), the duty ratio of the LED drive pulse PWM1 is reduced and the current flowing through the LED is reduced. Therefore, the extraction current is set larger than that on the left side (1).

  As described above, the PWM control circuit 42 refers to the setting table shown in FIG. 7 and determines the LED drive pulse PWM1 and the extraction current drive pulse PWM2 based on the waveform information of the amplitude voltage A, the conduction angle θ1, and the frequency f. The current is generated and supplied to the current control circuit 33 and the current extraction circuit 32, and the amount of each current is controlled. Therefore, it is necessary for the waveform information detection circuit 41 to accurately detect the waveform information of the amplitude voltage A, the conduction angle θ1, and the frequency f. Hereinafter, a method for detecting waveform information in the present embodiment will be described.

[Waveform information detection method in the present embodiment]
FIG. 10 is a configuration diagram of the waveform information detection circuit 41. The waveform information detection circuit 41 includes an input unit (for example, an AD converter) 411 that inputs a rectified output voltage of the node a, a zero cross point detection unit 412 that detects a zero cross point of the input voltage waveform, and a rising edge detection unit. 413. As described above, the output voltage of the dimmer 10 may be input instead of the rectified output voltage at point a. Further, the waveform information detection circuit 41 calculates a cycle 2 * t0 from the time t0 between the zero cross points, and the conduction calculation that calculates the time t1 of the conduction interval from the time between the rising edge point and the next zero cross point. An interval calculation unit 415, a timer 416, and an amplitude voltage detection unit 417 that detects the amplitude voltage A of the AC power source are included. And it has the calculation part 418 which calculates the frequency f of output voltage, the conduction angle (theta) 1, and the amplitude voltage A of AC power supply.

  FIG. 11 is a flowchart of the waveform information detection method. As shown in the flowchart of FIG. 11, the waveform information detection circuit 41 in the LED dimming control device 40 of the present embodiment converts the rectified output voltage of the node a into a digital signal using, for example, an AD converter, The zero-cross points Z1-Z3 and the rising edge EG shown in FIG. 6B of the waveform of the output voltage are detected (S1).

By detecting these, the conduction interval t1 that is the time from the rising edge EG to the next zero-cross point Z2, Z3 and the half-period time t0 between zero-crosses are extracted, and the conduction angle in the angle range of the conduction interval t1 is extracted. θ1 and frequency f are obtained by the following calculation (S2).
θ1 = 180 * (t1 / t0)
f = 1 / (2 * t0)
Further, the waveform information detection circuit 41 detects the amplitude voltage A of the AC power supply from the voltage waveform at the node a (S3). In an example of this detection method, as described above, the phase angle θ2 when the voltage waveform of the node a reaches the voltage A2 at the node a where the triac is turned off is detected, and the amplitude voltage A is calculated by the equation (1).

  Then, based on the detected amplitude voltage A of the waveform information, the conduction angle θ1, and the frequency f, the control values of the LED current and the extraction current are extracted with reference to the setting table shown in FIG. S4). Based on these control values, the PWM control circuit 42 generates an LED drive pulse PWM1 and an extraction current drive pulse PWM2.

  Next, three examples of the method for detecting the amplitude voltage A of the AC power supply will be described.

[Method of detecting amplitude voltage A in the present embodiment (1)]
FIG. 12 is a flowchart showing a method (1) of detecting the amplitude voltage A in the present embodiment. The amplitude voltage detector 417 in FIG. 10 inputs the digital value of the voltage at the node a, detects the timing when the voltage A2 is reached, and based on the already detected period 2 * t0, the phase angle θ2 of the timing Is detected (S10). As described above, the voltage A2 is set to a voltage corresponding to the triac threshold voltage (or conduction maintaining voltage). Alternatively, the voltage A2 is preferably set to a voltage corresponding to a voltage that is lower than the theoretical threshold voltage in consideration of variations in the threshold voltage. Then, the phase angle θ2 at the timing when the voltage at the node a becomes the voltage A2 is detected.

  Then, the amplitude voltage detector 417 calculates the amplitude voltage A of the AC power supply voltage from the detected phase angle θ2 of the voltage A2 by the above-described equation (1) (S11). As described above, since the parameter K is a constant constant, the amplitude voltage A of the AC power supply voltage can be calculated with high accuracy.

[Method of detecting amplitude voltage A in the present embodiment (2)]
FIG. 13 is a flowchart showing an example of the detection method (2) of the amplitude voltage A in the present embodiment. The amplitude voltage detection unit 417 acquires the voltage f (X) at the sampling point within the voltage conduction period t1 of the node a (S20). In parallel with this, the AC power supply voltage AsinX at the sampling point in the conduction interval t1 is calculated by setting the amplitude voltage A of the AC power supply voltage to an assumed value (S21).

  Then, the difference (f (X) −AsinX) at each sampling point is calculated (S22) and integrated (S23). A new amplitude voltage A is obtained by calculation so that the integral value e becomes smaller (S24).

  Step S21 is executed again with the newly obtained amplitude voltage A, and steps S22, S23, and S24 are executed. By repeating this, the amplitude voltage A when the integral value e is closest to zero is output as the amplitude voltage A of the AC power supply voltage.

  With reference to FIG. 7, a method of detecting the amplitude voltage A will be described. The voltage at the node a in FIG. 7 and the AC power supply voltage do not necessarily match in the conduction interval t1. However, in the interval of time t2, the voltage at the node a is smaller than the AC power supply voltage by the triac conduction voltage, and this conduction voltage is generally very small. Therefore, although it is difficult to predict due to temperature characteristics, the AC power supply voltage is 100V, In the case of 220V or the like, the error between both voltages is small. Further, since the voltage at the node a is 1 / K times the AC power supply voltage in the period of time t3, the error is also very small.

  Therefore, by using the amplitude voltage A of the AC power supply voltage AsinX that substantially matches the voltage at the node a as described above, the amplitude voltage A can be detected to some extent accurately.

  FIG. 14 is a flowchart showing another example of the detection method (2) of the amplitude voltage A in the present embodiment. In this example, the amplitude voltage detection unit 417 acquires the voltage f (X) at the sampling point in the conduction interval t1 of the voltage of the node a (S30). This is the same as S20 in FIG. At the same time, the AC power supply voltage AnsinX at the sampling point in the conduction interval t1 is calculated by setting the amplitude voltage A of the AC power supply voltage to one of the amplitude voltages A1 to An of the existing commercial AC power supply in each country. (S31). Then, the difference (f (X) -AsinX) at each sampling point is calculated (S32) and integrated (S33).

  The above calculation is executed for all the amplitude voltages A1 to An of commercial AC power supplies in each country, and the amplitude voltage corresponding to the minimum integral value e is selected and output as the amplitude voltage A of the AC power supply voltage.

  The method of detecting the amplitude voltage A is based on the same concept as in the example of FIG.

  FIG. 15 is a flowchart showing another example of the detection method (2) of the amplitude voltage A in the present embodiment. This example is a modification of FIG. The amplitude voltage detection unit 417 acquires the voltage f (X) at the sampling point within the conduction interval t1 of the voltage at the node a (S40). At the same time, the AC power supply voltage AsinX at the sampling point in the conduction interval t1 is calculated by setting the amplitude voltage A of the AC power supply voltage to an assumed value (S41). These steps S40 and S41 are the same as steps S20 and S21 in FIG.

  In FIG. 15, the integrated value S of the voltage f (X) is calculated (S42), the integrated value Sy of the voltage AsinX is calculated (S43), and the difference S-Sy or the ratio S / Sy is calculated (S43). S44). Then, a new amplitude voltage A is calculated so that the difference becomes smaller or the ratio approaches 1, and the above calculation processes S41 to S44 are repeated. Then, the amplitude voltage A when the difference is the smallest or the ratio is closest to 1 is output.

  The method for detecting the amplitude voltage A is also based on the same concept as in the example of FIG.

  FIG. 16 is a flowchart showing another example of the detection method (2) of the amplitude voltage A in the present embodiment. This example is a modification of FIG. In this example, the amplitude voltage detection unit 417 acquires the voltage f (X) at the sampling point in the conduction interval t1 of the voltage of the node a (S50). This is the same as S30 in FIG. At the same time, the AC power supply voltage AnsinX at the sampling point in the conduction interval t1 is calculated by setting the amplitude voltage A of the AC power supply voltage to one of the amplitude voltages A1 to An of the existing commercial AC power supply in each country. (S51). This is the same as S31 in FIG.

  In FIG. 16, the integral value S of the voltage f (X) is calculated (S52), the integral value Sy of the voltage AsinX is calculated (S53), and the difference S-Sy or the ratio S / Sy is calculated (S53). S54).

  The above calculation is executed for all the amplitude voltages A1-An of commercial AC power supplies in each country, and the smallest differential value S-Sy or the amplitude voltage corresponding to the ratio S / Sy closest to 1 is selected, and AC Output as amplitude voltage A of the power supply voltage.

  The method for detecting the amplitude voltage A is also based on the same concept as in the example of FIG.

  FIG. 17 is a flowchart showing another example of the detection method (2) of the amplitude voltage A in the present embodiment. In this example, the amplitude voltage detection unit 417 acquires the voltage f (X) at the sampling point in the conduction interval t1 of the voltage at the node a (S60). This is the same as S40 in FIG. In parallel with this, the AC power supply voltage AnsinX at the sampling point in the conduction interval t1 is calculated by setting the amplitude voltage A of the AC power supply voltage to an assumed value, for example 1, (S61). This is similar to S41 of FIG.

  In FIG. 17, the integral value S of the voltage f (X) is calculated (S62), the integral value Sy of the voltage AsinX is calculated (S63), and the ratio S / Sy is calculated (S64). Then, the voltage amplitude A is calculated so that the ratio S / Sy becomes 1. Since the initial value of the amplitude voltage A is set to 1, the ratio S / Sy becomes equal to the amplitude voltage A as it is.

  The method for detecting the amplitude voltage A is also based on the same concept as in the example of FIG.

[Method of detecting amplitude voltage A in the present embodiment (3)]
In the detection method (3) of the amplitude voltage A in the present embodiment, the sampling method at the sampling point in the non-conduction interval t3 of the triac from the phase angle θ2 to the zero cross point Z2 in FIG. The voltage f (X) of the node a is detected, and the AC power supply voltage AsinX is calculated based on the assumed A. Further, considering that the AC power supply voltage is a proportional constant K times the voltage of the node a, the same The amplitude voltage A is obtained by the method.

As an example, the detection method (3) will be described with reference to FIG. First, the voltage f (X) of the node a at the sampling point in the non-conducting section t3 of the triac from the phase angle θ2 to the zero cross point Z2 is detected (S60), and AC based on the assumed A (for example, A = 1) The power supply voltage sinX is calculated (S61), and the integral values S and Sy are calculated (S62 and S63). Then, the ratio S / Sy of both integral values S and Sy is calculated (S64). The voltage amplitude A is calculated so that this ratio S / Sy becomes 1. Since the amplitude voltage A is set as A = 1, the ratio S / Sy satisfies the following equation.
S / Sy = A / K
Therefore,
A = K * S / Sy
According to the above detection method (3), since the sampling voltage of the node a in the non-conduction section t3 of the triac is used, the proportional constant K times becomes the actual AC power supply voltage, so that the accuracy is higher. The amplitude voltage A of the AC power supply voltage can be obtained.

  As described above, according to the present embodiment, the output voltage of the triac dimmer can be analyzed to accurately detect the waveform information of the AC power supply amplitude, frequency, and conduction angle by dimming control. It is possible to appropriately perform drive current control and triac pull-in current control.

AC: AC power supply 10: Dimmer 20: LED lighting fixture 40: LED dimming control device 41: Waveform information detection circuit 42: PWM control circuit (drive control circuit)
32: Current extraction circuit 33: Current control circuit

Claims (11)

In the LED dimming control device for controlling the dimming of the LED, which is supplied with the output voltage from the dimmer that inputs the AC voltage and outputs the phase-controlled output voltage,
A waveform information detection circuit for detecting a voltage of the output voltage in an off period in which the dimmer is turned off, and detecting an amplitude voltage of the AC voltage based on the detected voltage in the off period;
An LED dimming control device comprising: a drive control circuit that generates a drive pulse for driving and controlling the LED based on the amplitude voltage. In claim 1,
The waveform information detection circuit analyzes the waveform of the output voltage, and based on the timing of the rising edge of the waveform of the output voltage and the timing of the zero cross point of the output voltage, , Detecting the conduction angle from the rising edge to the zero cross point,
The LED dimming control device, wherein the drive control circuit generates the drive pulse based on the frequency or cycle and a conduction angle in addition to the amplitude voltage. In claim 1,
The waveform information detection circuit is an LED dimming control that detects an amplitude voltage of the AC voltage based on an arbitrary voltage in the off period and a phase angle at the arbitrary voltage among the voltages in the off period. apparatus. In claim 1,
The waveform information detection circuit includes: a first sampling voltage at a plurality of sampling points of the output voltage in the off period; and a second sampling voltage at the plurality of sampling points of the alternating voltage in the off period. An LED dimming control device that detects a voltage that minimizes the total value of the differences as an amplitude voltage of the AC voltage. In claim 1,
The waveform information detection circuit includes an integrated value of a first sampling voltage at a plurality of sampling points of the output voltage in the off period and a second sampling at the plurality of sampling points of the alternating voltage in the off period. An LED dimming control device that detects a voltage that makes the difference from the integrated value of the voltage the smallest or a voltage that makes the ratio of the two integrated values closest to 1 as the amplitude voltage of the AC voltage. In claim 1,
The waveform information detection circuit includes the integrated value of the first sampling voltage at a plurality of sampling points of the output voltage in the off period and the plurality of samplings in the case of an arbitrary amplitude voltage of the AC voltage in the off period. An LED dimming control device that detects an amplitude voltage of the AC voltage based on a ratio of the second sampling voltage to an integral value at a point. In the LED dimming control device for controlling the dimming of the LED, which is supplied with the output voltage from the dimmer that inputs the AC voltage and outputs the phase-controlled output voltage,
The voltage of the output voltage in a conduction angle range from the timing of the rising edge of the waveform of the output voltage to the timing of the zero cross point of the output voltage is detected, and the alternating current is detected based on the detected voltage at the conduction angle. A waveform information detection circuit for detecting the amplitude voltage of the voltage;
An LED dimming control device comprising: a drive control circuit that generates a drive pulse for driving and controlling the LED based on the amplitude voltage. In claim 7,
The waveform information detection circuit includes a first sampling voltage at a plurality of sampling points of the output voltage during the conduction angle period and a second sampling point at the plurality of sampling points of the AC voltage during the conduction angle period. An LED dimming control device that detects, as an amplitude voltage of the AC voltage, a voltage that minimizes a total value of differences from the sampling voltage. In claim 7,
The waveform information detection circuit includes an integrated value of a first sampling voltage at a plurality of sampling points of the output voltage during the conduction angle period, and a plurality of sampling points of the AC voltage during the conduction angle period. An LED dimming control device that detects, as an amplitude voltage of the AC voltage, a voltage that makes the difference between the integration value of the second sampling voltage the smallest or a voltage that makes the ratio of both the integration values closest to 1. In claim 7,
The waveform information detection circuit includes an integrated value of the first sampling voltage at a plurality of sampling points of the output voltage in the conduction angle period and an arbitrary amplitude voltage of the AC voltage in the conduction angle period. An LED dimming control device that detects an amplitude voltage of the AC voltage based on a ratio with an integrated value of a second sampling voltage at the plurality of sampling points. In any one of Claims 1 thru | or 10,
The drive control circuit is an LED dimming control device that generates a control signal for controlling an amount of current flowing through the dimmer based on the amplitude voltage.

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