JP7293824B2 - LIGHTING DEVICE, LIGHTING EQUIPMENT, CONTROL METHOD FOR LIGHTING DEVICE - Google Patents

Description

The present invention relates to a lighting device, a lighting fixture, and a control method for a lighting device.

In a lighting fixture using an LED (Light Emitting Diode) as a light source, it is necessary to convert energy input from an AC commercial power source into DC energy and output the DC energy to the LED. In addition, regulations have been established regarding harmonics of input current, and in Japan, limit values for harmonics of input current are defined by Japanese Industrial Standards. Therefore, the lighting device has a PFC (Power Factor Correction) circuit, which is a power factor correction circuit for suppressing harmonics of the input current and improving the power factor.

Also, the lighting device controls the brightness of the LED. Since the brightness of the LED depends on the magnitude of the LED current, the lighting device has a current control circuit that controls the magnitude of the output current to be constant. In particular, there is a case where the PFC circuit and the current control circuit are realized by one circuit.

As a control method for the current control circuit, feedback control is applied in which the magnitude of the current being output is detected, and based on the difference from the target value, the control amount is corrected so that the current of the target magnitude is output. be.

Japanese Patent Application Laid-Open No. 2009-213280

Due to full-wave rectification in the process in which the lighting device converts AC energy into DC energy, pulsation with a frequency twice as high as the commercial frequency occurs in the output voltage of the PFC circuit. The current control circuit receives the voltage output by the PFC circuit and operates to output a desired amount of current. However, since there is a delay in control response in feedback control, a ripple current with a frequency double that of the AC power supply is superimposed on the current output to the light source. The superimposition of ripple current has the problem of causing flickering due to brightness of light and flickering in video camera images.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a lighting device, a lighting fixture, and a control method for the lighting device that can suppress the ripple current from being superimposed on the output current of the lighting device. With the goal.

A lighting device according to the invention of the present application includes a rectifying circuit that rectifies an AC voltage, a PFC circuit that suppresses harmonics and improves a power factor, and a switching element. a current control circuit that converts the current into a value, and a controller that controls the switching element, the controller detects the output current of the current control circuit and feeds back the output current to a predetermined target current. a calculation unit that calculates a first control amount to be controlled; a correction unit that calculates a second control amount that suppresses variations in the output current caused by pulsation of the output voltage of the PFC circuit in feedforward control; a multiplication unit that outputs a multiplication result obtained by multiplying the controlled variable by the second controlled variable, the control unit changing the conduction time of the switching element according to the multiplication result, and the correction unit: The smaller the amplitude of the AC voltage, the larger the difference between the instantaneous value of the output voltage and the average value of the output voltage is multiplied by a larger coefficient to increase the second control amount. to change the second control amount.
A lighting fixture according to the invention of the present application has a rectifier circuit that rectifies an AC voltage, a PFC circuit that suppresses harmonics and improves a power factor, and a switching element, and the output of the PFC circuit is converted to a predetermined current. a current control circuit that converts the current into a value, and a controller that controls the switching element, the controller detects the output current of the current control circuit and feeds back the output current to a predetermined target current. a calculation unit that calculates a first control amount to be controlled; a correction unit that calculates a second control amount that suppresses variations in the output current caused by pulsation of the output voltage of the PFC circuit in feedforward control; a multiplication unit that outputs a multiplication result obtained by multiplying the controlled variable by the second controlled variable, the control unit changing the conduction time of the switching element according to the multiplication result, and the correction unit: The smaller the amplitude of the AC voltage, the larger the difference between the instantaneous value of the output voltage and the average value of the output voltage is multiplied by a larger coefficient to increase the second control amount. and a lighting device for changing the second control amount, and a light source for lighting by the lighting device.
A control method for a lighting device according to the present invention detects an output current of a current control circuit that has a switching element and converts the output of a PFC circuit into a predetermined current value; calculating a first control amount for feedback control to the target current; and second control for suppressing fluctuations in the output current caused by pulsation of the output voltage of the PFC circuit connected to the rectifier circuit by feedforward control. changing the conduction time of the switching element according to the multiplication result obtained by multiplying the first controlled variable and the second controlled variable; and amplitude of the AC voltage input to the rectifier circuit. is smaller , the second control amount is increased by multiplying the difference between the instantaneous value of the output voltage and the average value of the output voltage by a larger coefficient, and the second control amount is increased according to the magnitude of the amplitude of the AC voltage. and changing the control amount.
A control method for a lighting device according to the present invention detects an output current of a current control circuit that has a switching element and converts the output of a PFC circuit into a predetermined current value; calculating a first control amount for feedback control to the target current; and second control for suppressing fluctuations in the output current caused by pulsation of the output voltage of the PFC circuit connected to the rectifier circuit by feedforward control. changing the conduction time of the switching element according to the multiplication result obtained by multiplying the first controlled variable and the second controlled variable; and amplitude of the AC voltage input to the rectifier circuit. is smaller , the difference between the instantaneous value of the output voltage and the average value of the output voltage is multiplied by a larger coefficient to increase the second control amount.

Other features of the invention will become apparent below.

According to the present invention, by applying feedforward control according to the height of the pulsating voltage in addition to feedback control, it is possible to suppress the ripple current of the double frequency of the AC power supply. As a result, it is possible to suppress flickering due to brightness of light and to suppress occurrence of flicker in video camera images.

1 is a configuration diagram of a lighting device and a lighting fixture according to Embodiment 1; FIG. It is a figure which shows the circuit configuration example of a PFC circuit and its periphery. 4 is a timing chart showing the operation of the PFC circuit; 4 is a timing chart showing the operation of the current control circuit; FIG. 10 is a diagram showing waveforms of output current under feedback control; FIG. 4 is a diagram showing waveforms of output current when feedforward control is performed in addition to feedback control; 4 is a functional block diagram of a control unit; FIG. 4 is a flow chart showing the contents of control by the current control circuit; FIG. 9A is a diagram showing the waveform of the output current when feedback control is performed. FIG. 9B is a diagram showing the waveform of the output current when feedforward control is performed. FIG. 4 is a diagram showing the relationship between ripple current and the capacitance of a smoothing capacitor; 4 is a flowchart showing control for changing the correction amount according to the input voltage; FIG. 4 is a diagram showing waveforms when an instantaneous power failure occurs in feedback control; FIG. 4 is a diagram showing waveforms when an instantaneous power failure occurs in feedforward control; FIG. 10 is a configuration diagram of a lighting device and a lighting fixture according to Embodiment 2; FIG. 10 is a configuration diagram of a lighting device and a lighting fixture according to Embodiment 3;

A lighting device, a lighting fixture, and a control method for a lighting device according to embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the same or corresponding components, and repetition of description may be omitted. In addition, this invention is not limited by description of embodiment.

Embodiment 1.
FIG. 1 is a configuration diagram of a lighting device 100 and a lighting fixture 200 according to Embodiment 1. FIG. A lighting fixture 200 is connected to an AC power supply 1 . The lighting fixture 200 includes an input filter 2 that removes high-frequency components of the alternating current output from the alternating current power supply 1, and a lighting device that converts the power supplied from the alternating current power supply 1 into a direct current that can be input to the light source 8 and outputs the direct current. 100 and a light source 8 that is lit by power supplied from the lighting device 100 . The light source 8 is composed of, for example, an LED group in which a plurality of LEDs are connected in series or in parallel. One end of the LED group is connected to the positive DC bus, and the other end of the LED group is connected to the negative DC bus. The light source 8 can be an LED or an organic EL (Electro Luminescence) connected to the lighting device 100 .

The lighting device 100 includes an input filter 2, a rectifier circuit 3 connected to the input filter 2, a filter capacitor 4 connected in parallel to the rectifier circuit 3, a PFC circuit 5, a current control circuit 7, and the PFC circuit 5. A control unit 11 for control and a control unit 9 for controlling the current control circuit 7 are provided. FIG. 2 is a diagram showing a circuit configuration example of the PFC circuit 5 and its peripherals. FIG. 2 shows filter capacitor 4 and control unit 11 .

The lighting device 100 has the function of suppressing harmonics of the current input from the AC power supply 1 to improve the power factor, and converting the power output from the rectifier circuit 3 into DC power and supplying it to the light source 8 . . The lighting device 100 includes a PFC circuit 5 for suppressing harmonics of the current input from the AC power supply 1 to improve the power factor, a smoothing capacitor 6 for smoothing the output voltage of the PFC circuit 5, and an output to the light source 8. and a current control circuit 7 for controlling the magnitude of the current applied.

An input filter 2 arranged between the AC power supply 1 and the rectifier circuit 3 has a coil 2a and a filter capacitor 2b, and reduces high frequency components superimposed on the current output from the AC power supply 1. FIG. The coil 2a is connected in series with the AC power supply 1. As shown in FIG. One end of the coil 2a is connected to one end of the AC power supply 1, and the other end of the coil 2a is connected to the filter capacitor 2b and the rectifier circuit 3. The other end of filter capacitor 2b is connected to AC power supply 1 and rectifier circuit 3 .

The rectifier circuit 3 is arranged between the input filter 2 and the PFC circuit 5 and converts AC power supplied from the AC power supply 1 into DC power. The rectifier circuit 3 is composed of, for example, a diode bridge in which four diodes are combined. The configuration of the rectifier circuit 3 is not limited to this, and may be configured by combining MOSFETs, which are unidirectional conduction elements. Any circuit that rectifies AC power can be employed as the rectifier circuit 3 .

A filter capacitor 4 is connected in parallel with the output of the rectifier circuit 3 and smoothes the output voltage of the rectifier circuit 3 . One end of the filter capacitor 4 is connected to the positive DC bus, and the other end of the filter capacitor 4 is connected to the negative DC bus.

PFC circuit 5 is arranged between rectifier circuit 3 and current control circuit 7 . As shown in FIG. 2, the PFC circuit 5 has a MOSFET 5b, which is a switching element, a coil 5a, and a diode 5c. The PFC circuit 5 boosts the output voltage of the rectifier circuit 3 and outputs the boosted voltage to the smoothing capacitor 6 by ON/OFF control of the MOSFET 5 b by the control unit 11 . In addition, the PFC circuit 5 has a function of suppressing harmonics of the input current and improving the power factor by control described later. In Embodiment 1, an example in which the PFC circuit 5 is configured by a boost chopper circuit will be described. In addition to the boost chopper circuit, the PFC circuit 5 may be configured by a circuit such as a boost/boost chopper circuit, a flyback circuit, a flyforward circuit, a SEPIC (Single Ended Primary Inductor Converter), a Zeta converter, or a Cuk converter. .

The coil 5a is arranged between the filter capacitor 4 and the MOSFET 5b on the positive side DC bus. The coil 5a is formed, for example, by winding an insulating wire around the core. One end of the coil 5 a is connected to one end of the filter capacitor 4 . The other end of coil 5a is connected to the anode of diode 5c. Voltages with different polarities are applied to the coil 5a as the MOSFET 5b is turned on and off. The coil 5a also has an auxiliary winding for zero current detection, which will be described later. One end of the auxiliary winding is connected to the negative electrode side DC bus, and the other end is connected to the zero current detection section 11g provided in the control section 11 .

The drain of the MOSFET 5b is connected to the coil 5a and the anode of the diode 5c on the positive DC bus. The source of the MOSFET 5b is connected to the other end of the filter capacitor 4 and the other end of the smoothing capacitor 6 on the negative DC bus. A gate of the MOSFET 5 b is connected to the control section 11 . A control signal output from the control unit 11 is input to the gate of the MOSFET 5b. On/off control of the MOSFET 5b is performed by inputting the control signal.

Diode 5c is arranged between MOSFET 5b and smoothing capacitor 6 on the positive side DC bus. The anode of the diode 5c is connected to the coil 5a and the MOSFET 5b, and the cathode of the diode 5c is connected to the smoothing capacitor 6.

As shown in FIG. 1, smoothing capacitor 6 is arranged between PFC circuit 5 and current control circuit 7 . One end of the smoothing capacitor 6 is connected to the positive side DC bus, and the other end of the smoothing capacitor 6 is connected to the negative side DC bus.

The control unit 11 shown in FIG. 2 includes a voltage detection unit 11b, a zero current detection unit 11g, a calculation unit 11c, and a drive unit 11d. The voltage detection unit 11b detects the height of the voltage output from the PFC circuit 5, and transmits the detection result to the calculation unit 11c. The voltage detection unit 11b can be, for example, a voltage dividing circuit in which a plurality of resistors are connected in series.

The zero current detector 11g detects the zero cross timing of the coil current and transmits it to the calculator 11c. For example, when the coil current drops to 0 A, the zero-cross timing can be detected by utilizing the reversal of the polarity of the auxiliary winding voltage. A comparator for detecting polarity reversal can be used as the zero current detector 11g.

The calculation unit 11c uses the output voltage of the PFC circuit 5 transmitted from the voltage detection unit 11b to perform calculation for feedback control so that the output voltage of the PFC circuit 5 has a predetermined magnitude, and the MOSFET 5b is Outputs a signal for on/off control. More specifically, the time during which the MOSFET 5b is turned on is changed so that the difference between the voltage transmitted from the voltage detection section 11b and the reference voltage Vref1 becomes small. Further, the calculation unit 11c is configured to have a function of A/D converting the voltage transmitted from the voltage detection unit 11b, and can be digitally controlled using a microcomputer or the like. In this case, in addition to eliminating the need for Vref1, it is also possible to reduce the size of the controller 11 by integrating an analog circuit.

The drive unit 11d converts the signal transmitted from the arithmetic unit 11c into a voltage large enough to drive the gate of the MOSFET 5b, and applies the voltage to the MOSFET 5b.

FIG. 3 is a timing chart showing the relationship between the current flowing through the coil 5a constituting the PFC circuit 5 shown in FIG. 1, the drain voltage of the MOSFET 5b, and the gate voltage of the MOSFET 5b. 3 shows, from top to bottom, the current of the AC power supply 1 input to the lighting device 100, the current flowing through the coil 5a, the zero current detection signal output from the zero current detection unit 11g, the drain voltage of the MOSFET 5b, and the gate voltage of the MOSFET 5b. shown. The horizontal axis represents time.

In FIG. 3, for convenience of explanation, the cycle of turning on and off the gate voltage of the MOSFET 5b is shown longer than it actually is. The period in which the gate voltage of the MOSFET 5b is turned on and off is equal to the time from when the gate voltage of the MOSFET 5b changes from off to on until the gate voltage of the MOSFET 5b changes from off to on again.

When the MOSFET 5b is turned on, a current path of the AC power supply 1, the rectifier circuit 3, the coil 5a and the MOSFET 5b is formed, and the AC power supply 1 is short-circuited via the coil 5a. Therefore, the current flowing through the coil 5a increases, and energy is accumulated in the coil 5a.

After the on-time set in the calculation unit 11c has elapsed, the MOSFET 5b is turned off. When the MOSFET 5b is turned off, a current path of the coil 5a, the diode 5c and the smoothing capacitor 6 is formed. The energy stored in the coil 5a is released through this path, and the smoothing capacitor 6 is charged.

When the current flowing through the coil 5a becomes zero, the MOSFET 5b is turned on again. The control for turning on the MOSFET 5b immediately after the coil current becomes zero is called current critical mode control. Due to a series of ON/OFF operations of the MOSFET 5b, the current flowing through the coil 5a has a triangular waveform, and its apex forms a sinusoidal envelope indicated by a dotted line. At this time, the current input from the AC power supply 1 has its high-frequency components removed by the input filter 2, and the average value of the coil current flowing in the coil 2a is input, resulting in a sinusoidal current waveform.

At this time, the control unit 11 detects the voltage applied to the smoothing capacitor 6 and performs feedback control so that the detected voltage follows a target value, thereby controlling the ON time of the MOSFET 5b. When the on-time of the MOSFET 5b is feedback-controlled, if the on-time changes greatly, the envelope of the peak of the current flowing through the coil 5a does not become a sine wave, and the input current of the AC power supply 1 can be made into a sine wave. Can not. Therefore, in the control unit 11, the response time of the feedback control is set so that the loop gain of the feedback control is equal to or less than 1 time (0 dB) in 1/2 cycle or more of one cycle of the AC power supply 1. FIG. In other words, the response time of the feedback control is set to be 1 time (0 dB) or less at a frequency that is 2 times or less the frequency of the AC power supply 1 .

Specifically, when the power supply frequency is 50 Hz, the frequency of the half cycle (half wave) of the power supply frequency is 100 Hz or less, that is, the period is 10 msec or more, and the feedback control loop gain is 1 time (0 dB) or less. , the feedback control is set so as not to respond with a period shorter than 1/2 of the power supply period. As a result, the variation in the ON time of the MOSFET 5b is suppressed within 1/2 of the power supply cycle, and the envelope of the peak of the current flowing through the coil 5a becomes a sinusoidal waveform.

In feedback control, the same effect can be obtained by setting the update period of the on-time to a period corresponding to half the period of the AC power supply 1 or a period longer than a period corresponding to half the period of the AC power supply 1. be able to.

After detecting zero current, a slight delay time is provided until the MOSFET 5b is turned on, and the MOSFET 5b can be turned on near the bottom of the drain voltage oscillation during the free oscillation period of the drain voltage of the MOSFET 5b. As a result, sharp fluctuations in the drain voltage can be suppressed, and noise caused by switching can be suppressed.

Next, the configuration and operation of the current control circuit 7 will be described in detail.

As shown in FIG. 1, the current control circuit 7 includes a switching element 7a composed of, for example, a MOSFET, a coil 7b, a diode 7c, and a filter capacitor 7d. The switching element 7a is arranged in series with the positive electrode side DC bus. The drain of switching element 7a is connected to one end of smoothing capacitor 6 and the cathode of diode 5c shown in FIG. The source of switching element 7a is connected to the cathode of diode 7c and one end of coil 7b. A gate of the switching element 7a is connected to the driving section 9d. A control signal output from the control unit 9 is input to the gate of the switching element 7a. The control signal is a signal for on/off controlling the switching element 7a.

One end of the coil 7b is connected to the source of the switching element 7a and the cathode of the diode 7c. The other end of the coil 7b is connected to one end of the filter capacitor 7d and one end of the light source 8 shown in FIG. The cathode of the diode 7c is connected to the source of the switching element 7a and one end of the coil 7b. The anode of the diode 7c is connected to the other end of the smoothing capacitor 6, the other end of the filter capacitor 7d and the other end of the light source 8 shown in FIG.

The current control circuit 7 in FIG. 1 is composed of a step-down chopper circuit, but in addition to the step-down chopper circuit, it is also configured with a step-up/step-down chopper circuit, a flyback circuit, a flyforward circuit, a SEPIC, a Zeta converter, or a Cuk converter. It may have been

FIG. 4 is a timing chart showing the relationship between the current flowing through the light source 8, the current flowing through the coil 7b, and the gate voltage of the switching element 7a. FIG. 4 shows, from top to bottom, the current flowing through the light source 8, the current flowing through the coil 7b, and the gate voltage of the switching element 7a. The horizontal axis represents time.

The switching cycle Tsw is equal to the time from when the control signal for the switching element 7a changes from off to on until the control signal for the switching element 7a changes from off to on again. The switching cycle Tsw is set in advance in the calculation section 9c. The ON time Ton is equal to the time from when the control signal for the switching element 7a changes from OFF to ON until it changes from ON to OFF.

When the control signal for the switching element 7a changes from off to on, the switching element 7a is turned on. Then, a current path is formed through the smoothing capacitor 6, the switching element 7a, the coil 7b and the filter capacitor 7d, and the current flowing through the coil 7b increases as shown in FIG.

When the control signal for the switching element 7a changes from on to off, the switching element 7a is turned off. Then, a current path is formed through the coil 7b, the filter capacitor 7d and the diode 7c, and the current flowing through the coil 7b shown in FIG. 4 is reduced to zero. When the switching cycle Tsw has passed, the control signal for the switching element 7a changes from off to on. As a result, the switching element 7a is turned on again.

At this time, the current flowing through the coil 7b has a triangular waveform, but the current output to the light source 8 is smoothed by the filter capacitor 7d, and the average value of the current flowing through the coil 7b is output from the current control circuit 7. . The current control circuit 7 converts the output of the PFC circuit 5 into a predetermined current value. After the current flowing through the coil 7b is reduced to zero, a resonance current is generated in the resonance circuit formed by the parasitic capacitance of the switching element 7a and the coil 7b, but the description is omitted.

When controlling the current flowing through the light source 8 to dim the light source 8, the computing unit 9c turns on the switching element 7a according to the target value of the output current while keeping the switching cycle Tsw for turning on the switching element 7a constant. Vary the time Ton. A control method for obtaining a specific output by adjusting the on-time Ton in this way is called duty control, since the ratio of the on-time Ton to the switching period Tsw is called duty.

Moreover, as a control method of the current control circuit 7, there is also a method in which the switching period Tsw is not fixed. Specifically, it is a critical mode control method similar to the PFC circuit 5. In this case, it is necessary to provide an auxiliary winding for detecting zero current in the coil 7b. After detecting zero current in the auxiliary winding, a slight delay time is provided until the switching element 7a is turned on. It is also possible to turn on the switching element 7a. As a result, sharp fluctuations in the drain voltage can be suppressed, and noise caused by switching can be suppressed.

As shown in FIG. 1, the control section 9 includes a correction section 9b, an input voltage detection section 9f, a calculation section 9c, a drive section 9d and a multiplier 9e.

The correction unit 9b detects the output voltage of the PFC circuit 5 (hereinafter sometimes simply referred to as output voltage) and calculates the average value of the output voltage. Further, the correction unit 9b calculates a second control amount that enables feedforward according to the difference between the instantaneous value and the average value of the output voltage. The second controlled variable is, for example, a value proportional to the ratio of the instantaneous value to the average value, or a value proportional to the ratio of the difference between the instantaneous value and the average value to the average value. Also, the target value of the output voltage of the PFC circuit 5 can be used as the average value of the output voltage of the PFC circuit 5 . In this case, the correction unit 9b uses the target value of the output voltage as the average value of the output voltage. By using the target value of the output voltage, it is possible to reduce the calculation load of the average value. The correction unit 9b outputs the calculated second control amount to the multiplier 9e.

The input voltage detector 9f detects the height of the input voltage and transmits it to the corrector 9b. The input voltage detection unit 9f can be a voltage dividing circuit in which a plurality of resistors are connected in series.

The calculation unit 9c detects the output current of the current control circuit 7 transmitted from the shunt resistor 7e (hereinafter sometimes simply referred to as output current). The calculator 9c calculates a first controlled variable for feedback-controlling the output current to a predetermined target current. The first control amount is calculated using the output current for feedback control so that the output current has a predetermined magnitude. The first control amount is a signal for on/off controlling the switching element 7a.

More specifically, the ON time of the switching element 7a is changed so that the difference between the voltage obtained from the shunt resistor 7e and the reference voltage Vref2 is reduced. For example, when the voltage obtained from the shunt resistor 7e is higher than the reference voltage Vref2, the ON time of the switching element 7a is shortened. On the contrary, when the voltage obtained from the shunt resistor 7e is lower than the reference voltage Vref2, the time for turning on the switching element 7a is extended.

The calculation unit 9c is configured to have a function of A/D converting the voltage obtained from the shunt resistor 7e, and can be digitally controlled using a microcomputer or the like. In this case, in addition to eliminating the need for Vref2, it is possible to reduce the size of the controller 9 by integrating an analog circuit.

The multiplier 9e multiplies the first controlled variable and the second controlled variable, and outputs the multiplication result to the driving section 9d. The driving unit 9d converts the signal transmitted from the multiplier 9e into a voltage capable of driving the gate of the switching element 7a, and applies the voltage to the gate of the switching element 7a.

Although the control unit 9 and the control unit 11 are described as separate configurations, in the case of digital control using a microcomputer or the like, the control unit 9 and the control unit 11 can be integrated into one microcomputer to reduce the size of the circuit. can be done. The MOSFET 5b and the switching element 7a can be made of, for example, a silicon-based semiconductor. According to another example, MOSFET 5b and switching element 7a may be formed by a wide bandgap semiconductor. Wide bandgap semiconductors are silicon carbide, gallium nitride based materials or diamond. By using a wide bandgap semiconductor for the MOSFET 5b and the switching element 7a, conduction loss can be reduced. Also, even if the switching frequency, that is, the driving frequency is set to a high frequency, the heat dissipation is improved. Therefore, the heat dissipation components of the PFC circuit 5 and the current control circuit 7 can be reduced in size or eliminated.

The current control circuit 7 operates with the output voltage of the PFC circuit 5 as an input, but there is a delay in control response with only feedback control. A ripple current with a double frequency of the power supply is superimposed. Ripple current causes flickering due to brightness of light and flicker in video camera images.

FIG. 5 is a diagram showing the waveform of the output current under feedback control. When the output voltage of the PFC circuit 5 drops due to pulsation, control is applied to extend the ON time so that the output current does not drop. However, since there is a delay in response, the timing at which the ON time of the switching element 7a reaches its maximum is later than the timing at which the output voltage of the PFC circuit 5 reaches the ripple bottom. As a result, a ripple occurs in the output current of the current control circuit 7, which is the current flowing through the LED 8. FIG.

FIG. 6 is a diagram showing an output current waveform when feedforward control is performed using the output voltage of the PFC circuit 5 in addition to feedback control in the first embodiment. The correction unit 9b detects the output voltage of the PFC circuit 5 and calculates a second control amount that enables feedforward according to the height of the pulsating voltage. More specifically, when the instantaneous value of the output voltage of the PFC circuit 5 is higher than the average value of the output voltage, the correction unit 9b performs second control to shorten the conduction time of the switching element 7a compared to the previous control. Calculate quantity. Shortening the ON time of the switching element 7a reduces the peak value of the ripple current. Conversely, when the instantaneous value of the output voltage of the PFC circuit 5 is lower than the average value of the output voltage, the correction unit 9b calculates a second control amount that makes the conduction time of the switching element 7a longer than in the previous control. do. Lengthening the ON time of the switching element 7a raises the bottom value of the ripple current. In this way, by using the second control amount that suppresses fluctuations in the output current caused by the pulsation of the output voltage in feedforward control, it is possible to correct the delay in response due to conventional feedback control, thereby suppressing the ripple current. can do.

In FIG. 6, as a result of controlling the conduction time of the switching element 7a by the control unit 9, the timing at which the pulsation of the output voltage reaches its maximum value and the timing at which the conduction time of the switching element 7a reaches its minimum coincides in period 1. , the timing at which the pulsation of the output voltage reaches its minimum value coincides with the timing at which the conduction time of the switching element 7a reaches its maximum.

FIG. 7 is a functional block diagram of the correction section 9b and the calculation section 9c. The correction unit 9b includes a detection unit 9b1, a memory 9b2, a second control amount calculation unit 9b3, and an average value calculation unit 9b4. The calculator 9c includes a detector 9c1 and a first control amount calculator 9c3.

The detection unit 9b1 of the correction unit 9b detects the output voltage of the PFC circuit 5, and transmits the detection result to the second control amount calculation unit 9b3 and the average value calculation unit 9b4. The detection unit 9b1 can be a voltage dividing circuit in which a plurality of resistors are connected in series. Moreover, in the case of digital control, it also has an A/D converter.

The average value calculator 9b4 uses the signal transmitted from the detector 9b1 to calculate the average value of the output voltage of the PFC circuit 5, and stores the average value in the memory 9b2. The second control amount calculator 9b3 calculates the second control amount using the signal transmitted from the detector 9b1 and the signal transmitted from the memory 9b2, and transmits the second control amount to the multiplier 9e.

The detection section 9c1 of the calculation section 9c detects the voltage of the shunt resistor 7e and transmits the detection result to the first control amount calculation section 9c3. The first controlled variable calculator 9c3 calculates the first controlled variable using the signal transmitted from the detector 9c1, and transmits the first controlled variable to the multiplier 9e. The multiplier 9e multiplies the second controlled variable and the first controlled variable transmitted from the second controlled variable calculator 9b3 and the first controlled variable calculator 9c3, and outputs the multiplication result to the drive unit 9d.

FIG. 8 is a flow chart showing the control contents of the current control circuit 7. As shown in FIG. When AC power is supplied to lighting device 100, lighting operation is started in step S1. The calculation unit 9c detects the output current in step S2. As mentioned above, the output current can be detected as a voltage value. After that, the calculation unit 9c calculates the difference between the detected output current and the target current in step S3, and calculates the first control amount by feedback in step S4. The first controlled variable is a controlled variable for feedback-controlling the output current to a predetermined target current.
Assuming that the first controlled variable is Ton(t), Iref is the target current, and Idec is the detected output current, the first controlled variable is calculated by, for example, Equation 1 below.
Ton(t)=Ton(t-1)×(1+(Iref-Idec)×B) Equation 1
B is a value that determines the speed of feedback response, and if you want to speed up the response, increase B.

The correction unit 9b detects the output voltage of the PFC circuit 5 in step S7. After that, the correction unit 9b calculates the average of the output voltage of the PFC circuit 5 in step S8, and calculates the difference between the detected value of the output voltage and the average voltage in step S9. After that, in step S10, a second control amount is calculated by feedforward. The second controlled variable is a controlled variable that suppresses variations in the output current caused by pulsation of the output voltage in feedforward control.
Assuming that the output voltage of the PFC circuit 5 is Vdec, and the average voltage of the PFC circuit 5 is Vave, the second control amount is calculated, for example, by Equation 2 below.
Second controlled variable={1+(Vave-Vdec)×A} Equation 2
A can be a fixed value. As will be described later with reference to FIG. 11, A can also correspond to the magnitude of AC power.

In step S5, the first controlled variable and the second controlled variable are multiplied by the multiplier 9e to obtain the ON time corrected by the feedforward control. At step S6, the controller 9 changes the conduction time of the switching element 7a according to the multiplication result. Specifically, the switching element 7a is turned on according to the corrected ON time.

FIG. 9A is a diagram showing the waveform of the output current when feedback control is performed. FIG. 9B is a diagram showing a waveform of an output current in which ripple current is suppressed by feedforward control. Current value 1 represents the average current under both conditions, and both are equal values. Current value 2 is the peak current in the current waveform when conventional feedback control is performed. A current value 3 is the difference between the current values 1 and 2 .

When using an LED as the light source 8, the output light amount is determined in proportion to the average current. In both cases of FIG. 9A and FIG. 9B, since the average current is a current value of 1, the amount of light is the same. When using an LED as a light source, it is necessary to ensure that the peak value of the output current does not exceed the maximum rated current of the LED. In the conventional feedback control, the ripple current is superimposed on the current output by the current control circuit 7, so the average current may not be increased due to the limitation of the maximum rated current. In other words, the average current cannot be brought close to the current value 2. In this case, it is necessary to increase the number of LED chips in order to secure the necessary amount of light, resulting in an increase in cost.

On the other hand, in Embodiment 1, since the ripple current can be suppressed by feedforward, the average current can be increased more than in the conventional art. Compared to the case where the conduction time of the switching element 7a is changed based only on the first control amount, the average value of the output current can be brought closer to the maximum rated current of the light source. If the ripple current can be completely eliminated from the output current, the average current can be matched to the current value of 2. Adoption of feedforward enables cost reduction of LED through reduction of the number of LED chips.

FIG. 10 is a diagram showing the relationship between the magnitude of the ripple current of the current output by the current control circuit 7 and the magnitude of the capacitance of the smoothing capacitor 6. As shown in FIG. If the capacity of the smoothing capacitor 6 is reduced, the pulsation of the output voltage of the PFC circuit 5 is increased, and the ripple current is also increased. In the case of "conventional control by feedback", it was necessary to increase the capacity of the smoothing capacitor 6 in order to suppress the ripple current, which resulted in an increase in size and cost of the parts. In contrast, in Embodiment 1, the ripple current can be suppressed by feedforward, so the capacity of the smoothing capacitor 6 can be reduced. In the example of FIG. 10 , the capacity of the smoothing capacitor 6 can be reduced from capacity 1 to capacity 2 . A reduction in capacity enables cost reduction of the device.

As the voltage input from the AC power supply 1 decreases, the pulsating voltage superimposed on the output voltage of the PFC circuit 5 increases. Therefore, in order to sufficiently obtain the effect of suppressing the ripple current, it is necessary to increase the correction amount by increasing the coefficient A in the above-described "Equation 2" as the voltage input from the AC power supply 1 decreases. In other words, the lower the AC power input to the rectifier circuit 3, the larger the difference between the instantaneous value Vdec of the output voltage and the average value Vave of the output voltage is multiplied by a larger coefficient to increase the second control amount. As an example of such processing, the voltage of the AC power supply 1 can be determined, and the second control amount can be increased as the voltage of the AC power supply 1 is lower. With such processing, ripple current can be suppressed.

FIG. 11 is a flow chart showing control for changing the correction amount according to the input voltage. First, in step S20, the AC power supply 1 is turned on. Next, the voltage of the AC power supply 1 is detected in step S21. Next, in step S22, for example, a table is referred to determine a correction amount according to the detected voltage. As the voltage of the AC power supply 1 decreases, a larger correction amount is adopted. An example of the correction amount is the coefficient A described above. According to one example, a table that defines the correspondence between the input voltage and the correction amount is provided in the internal memory of the control unit 9, and the correction amount can be determined by referring to the table. After determining the correction amount in step S23, the process proceeds to step S24. In step S24, lighting of the light source 8 by the lighting device 100 is started, and the lighting state is maintained until the power is cut off.

In FIG. 6, the partial waveform of the ON time of the switching element 7a when the input voltage is 100V is shown by a broken line, and the waveform of the ON time of the switching element 7a when the input voltage is 200V is shown by a solid line. In the correction unit 9b, the ripple current corresponding to various input voltages can be suppressed by performing the process of increasing the second control amount as the AC power becomes lower.

The voltage of the AC power supply 1 may fluctuate or a momentary power failure (instantaneous power failure) may occur due to fluctuations in power demand or the occurrence of lightning.

FIG. 12 is a diagram showing waveforms of the output voltage of the PFC circuit 5 and the output current of the current control circuit 7 when an instantaneous power failure occurs in the voltage of the AC power supply 1 in conventional feedback control. Since power cannot be supplied from the AC power supply 1 during the period A in which the momentary power failure occurs, the output voltage of the PFC circuit 5 decreases due to the discharging of the smoothing capacitor 6 . After that, it takes a period from period A to period B until the output voltage of the PFC circuit 5 stabilizes. The waveform when it is assumed that there is no momentary power failure in the periods A and B is indicated by the dashed line, and the waveform becomes the solid line waveform due to the momentary power failure. When the current control circuit 7 is feedback-controlled, the output voltage of the PFC circuit 5 drops and the output current of the current control circuit 7 also drops because of the delay in response. This may result in the appearance of flicker due to the brightness of the light.

FIG. 13 is a diagram showing waveforms of the output voltage of the PFC circuit 5 and the output current of the current control circuit 7 when an instantaneous power failure occurs in the voltage of the AC power supply 1 in the feedforward control of the first embodiment. Since power cannot be supplied from the AC power supply 1 during the period A in which the momentary power failure occurs, the output voltage of the PFC circuit 5 decreases due to the discharging of the smoothing capacitor 6 . After that, it takes a period from period A to period B until the output voltage of the PFC circuit 5 stabilizes. However, when the current control circuit 7 is feedforward controlled, it is possible to perform correction so as to cancel out the influence of fluctuations in the output voltage of the PFC circuit 5 . Specifically, when the output voltage of the PFC circuit 5 drops, it acts to lengthen the ON time of the switching element 7a. As a result, it is possible to suppress a decrease in the output current of the current control circuit 7, thereby suppressing flickering due to brightness of light.

The modification referred to in the first embodiment can also be applied to the lighting device, the lighting fixture, and the control method of the lighting device according to the following embodiments. A lighting device, a lighting fixture, and a control method for a lighting device according to the following embodiments have many points in common with Embodiment 1, so differences from Embodiment 1 will be mainly described.

Embodiment 2.
FIG. 14 is a configuration diagram of a lighting device 100a and a lighting fixture 200a according to the second embodiment. A difference between the lighting fixture 200a according to the second embodiment and the lighting fixture 200 according to the first embodiment is that the lighting device 100a is used instead of the lighting device 100 in the lighting fixture 200a. The difference between the lighting device 100a according to the second embodiment and the lighting device 100 according to the first embodiment is that the lighting device 100a uses a synchronous rectification circuit 12 instead of the rectification circuit 3 and the PFC circuit 5. It is a point. That is, the rectifier circuit and the PFC circuit are configured with the synchronous rectifier circuit 12 .

The synchronous rectification circuit 12 has a function of converting AC power input from the AC power supply 1 into DC power, suppressing harmonics of the current, and improving the power factor. The synchronous rectification circuit 12 has MOSFETs 12a, 12b, 12c and 12d, which are switching elements, and a coil 12e. MOSFETs 12a, 12b, 12c, and 12d are ON/OFF-controlled by the control unit 11, so that the synchronous rectification circuit 12 boosts the voltage of the AC power supply 1 in addition to the rectification operation, and outputs the boosted voltage to the smoothing capacitor 6. . Further, the synchronous rectifier circuit 12 has the function of suppressing harmonics of the input current and improving the power factor, like the PFC circuit 5 in the first embodiment.

The coil 12e has one end connected to the filter capacitor 2b and the other end connected to the source of the MOSFET 12a and the drain of the MOSFET 12c. Voltages with different polarities are applied to the coil 12e as the MOSFETs 12a, 12b, 12c, and 12d are turned on and off. In addition, the coil 5e has an auxiliary winding for zero current detection, which will be described later. One end of the auxiliary winding is connected to the negative electrode side DC bus, and the other end is connected to the zero current detection section 11g provided in the control section 11. be done.

The drains of the MOSFETs 12a and 12b are connected to the smoothing capacitor 6 on the positive side DC bus. The sources of the MOSFETs 12c and 12d are connected to the smoothing capacitor 6 on the negative side DC bus. The source of MOSFET 12a is connected to the drain of MOSFET 12c and further connected to coil 12e. The source of the MOSFET 12b is connected to the drain of the MOSFET 12d, and further connected to the filter capacitor 2b and the AC power supply 1. Gates of the MOSFETs 12a, 12b, 12c, and 12d are connected to the control section 11, and control signals output from the control section 11 are input. On/off control of the MOSFETs 12a, 12b, 12c, and 12d is performed by inputting the control signal.

The operation of the synchronous rectifier circuit 12 can be explained from the operation of the PFC circuit 5. FIG. The coil 12e and the MOSFETs 12a and 12c of the synchronous rectification circuit 12 correspond to the coil 5a, the diode 5c and the MOSFET 5b of the PFC circuit 5, respectively. The coil 12e and the MOSFETs 12b and 12d correspond to the coil 5a, the diode 5c and the MOSFET 5b of the PFC circuit 5, respectively. According to the polarity of the voltage of the AC power supply 1, these alternately perform the same switching operation as the PFC circuit 5, thereby converting the AC power input from the AC power supply 1 into DC power and suppressing current harmonics. do.

By using the synchronous rectifier circuit 12 in place of the rectifier circuit 3 and the PFC circuit 5, the number of circuits can be reduced, so it is possible to reduce losses generated in switching elements such as MOSFETs or diodes. However, since the synchronous rectification circuit 12 does not have the filter capacitor 4 in the first embodiment, the pulsation of the output voltage of the synchronous rectification circuit 12 increases. Therefore, the ripple current of the output current of the current control circuit 7 becomes large.

In contrast, the ripple current can be suppressed by feedforward controlling the current control circuit 7 as described above. Therefore, by using the synchronous rectification circuit 12, it is possible to suppress an increase in ripple current while reducing loss.

Embodiment 3.
FIG. 15 is a configuration diagram of a lighting device 100b and a lighting fixture 200b according to Embodiment 3. As shown in FIG. A difference between the lighting fixture 200b according to the third embodiment and the lighting fixture 200 according to the first embodiment is that the lighting device 100b is used instead of the lighting device 100 in the lighting fixture 200b. A difference between the lighting device 100b according to the third embodiment and the lighting device 100 according to the first embodiment is that the lighting device 100b uses a DC conversion circuit 13 instead of the PFC circuit 5 and the current control circuit 7. The point is the configuration. That is, the PFC circuit and the current control circuit are configured with the DC conversion circuit 13 .

The DC conversion circuit 13 converts the DC power output from the rectifier circuit 3 into a desired DC current and outputs the DC current to the light source 8 . In addition, it has a function of suppressing harmonics of the current input from the AC power supply 1 to improve the power factor.

The DC conversion circuit 13 can be a SEPIC having a MOSFET 13a as a switching element, a first coil 13f, a second coil 13c, a coupling capacitor 13h, a diode 13b, and a shunt resistor 13e. The DC conversion circuit 13 has a function of controlling the magnitude of the current output to the light source 8, suppressing harmonics of the input current, and improving the power factor by controlling the ON/OFF of the MOSFET 13a by the control unit 9. .

A specific circuit configuration and operation will be described. One end of the first coil 13 f is connected to one end of the filter capacitor 4 . The other end of the filter capacitor 4 is connected to the negative side DC bus. The MOSFET 13a has a drain terminal, a source terminal, and a gate terminal for switching between these terminals. The MOSFET 13a has a drain terminal connected to the other end of the first coil 13f and is connected in parallel with the filter capacitor 4 via the first coil 13f.

One end of the coupling capacitor 13h is connected to the drain terminal of the MOSFET 13a. One end of the second coil 13c is connected to the other end of the coupling capacitor 13h. The other end of the second coil 13c is connected to the negative electrode side DC bus. The second coil 13c is connected in parallel with the MOSFET 13a through a coupling capacitor 13h. Note that the first coil 13f and the second coil 13c are configured as individual parts. In the SEPIC, a transformer having a configuration in which the first coil 13f and the second coil 13c are wound around the same core can be used, and the number of parts can be reduced.

The anode of the diode 13b is connected between one end of the second coil 13c and the other end of the coupling capacitor 13h. A smoothing capacitor 6 is connected to the cathode of the diode 13b. The other end of smoothing capacitor 6 is connected to shunt resistor 13e. A light source 8 is connected in parallel to the smoothing capacitor 6 .

The operation of the DC conversion circuit 13 can be explained from the operations of the PFC circuit 5 and the current control circuit 7 in the configuration 1 of the embodiment. In the DC conversion circuit 13, the first coil 13f and the MOSFET 13a are configured to correspond to the coil 5a and the MOSFET 5b of the PFC circuit 5, respectively. By performing switching operations similar to those of the PFC circuit 5, these elements convert AC power input from the AC power supply 1 into DC power and suppress current harmonics.

The ON time of the MOSFET 13a is controlled in the same manner as the current control circuit 7. FIG. That is, using the output current transmitted from the shunt resistor 13e, the first control amount for feedback control is calculated so that the output current of the DC conversion circuit 13 has a predetermined magnitude, and the MOSFET 13a is turned on/off. Outputs signals for control. More specifically, the ON time of the MOSFET 13a is changed so that the difference between the voltage transmitted from the shunt resistor 13e and the reference voltage Vref becomes smaller. For example, when the voltage transmitted from the shunt resistor 13e is higher than the reference voltage Vref, the time for turning on the MOSFET 13a is shortened. On the contrary, when the voltage transmitted from the shunt resistor 13e is smaller than the reference voltage Vref, the time for turning on the MOSFET 13a is extended.

The correction unit 9b detects the height of the voltage output from the rectifier circuit 3 and calculates the average value. Also, a second control amount that enables feedforward according to the difference between the instantaneous value and the average value is calculated. As the content of calculation of the second controlled variable, there is a method of using a value proportional to the ratio of the instantaneous value to the average value, or using a value proportional to the ratio of the difference between the instantaneous value and the average value to the average value. The corrector 9b outputs the second controlled variable to the multiplier 9e.

The multiplier 9e multiplies the first controlled variable and the second controlled variable to generate an on-time, and transmits it to the driving section 9d. A control signal from the driving section 9d drives the MOSFET 13a.

As a control method for the DC conversion circuit 13, there is also a method of performing critical mode control as in the case of the PFC circuit 5. FIG. In this case, it is necessary to provide an auxiliary winding for detecting zero current in the first coil 13f or the second coil 13c.

When the auxiliary winding is provided, after detecting zero current, a slight delay time is provided until the MOSFET 13a is turned on. You can also let As a result, sharp fluctuations in the drain voltage can be suppressed, and noise caused by switching can be suppressed.

In addition to the SEPIC, the DC conversion circuit 13 may be configured by a circuit such as a step-up/step-down chopper circuit, a flyback circuit, a flyforward circuit, a Zeta converter, or a Cuk converter.

By using the DC conversion circuit 13 instead of the PFC circuit 5 and the current control circuit 7, the number of circuits can be reduced, so that the loss generated in switching elements such as MOSFETs or diodes can be reduced. However, since the DC converter circuit 13 does not perform the step-up operation in Embodiment 1, but directly uses the output voltage of the rectifier circuit 3 to control the magnitude of the current output to the light source 8, the output of the DC converter circuit 13 is The current ripple current increases.

On the other hand, by adopting the above-described feedforward control for the DC conversion circuit 13, it is possible to suppress the ripple current. Therefore, by using the DC conversion circuit 13, it becomes possible to suppress the ripple current while reducing the loss.

The configuration shown in the above embodiment shows an example of the content of the present invention, and it is possible to combine the configuration 1, 2, and 3 of the embodiment, or to combine it with another known technique, A part of the configuration can be omitted or changed without departing from the gist of the present invention.

1 AC power supply 2 Input filter 3 Rectifier circuit 4 Capacitor 5 PFC circuit 6 Smoothing capacitor 7 Current control circuit 8 Light source 9, 11 Control unit 12 Synchronous rectification circuit 13 DC conversion circuit 2a, 5a , 7b, 12e coil, 13f first coil, 13c second coil, 2b, 7d filter capacitor, 13h coupling capacitor, 5b, 12a, 12b, 12c, 12d, 13a MOSFET, 7a switching element, 5c, 7c, 13b diode, 9b correction unit 9c, 11c operation unit 9d, 11d drive unit 9f input voltage detection unit 9e multiplier 11b voltage detection unit 11g zero current detection unit 9b1, 9c1 detection unit 9b2, 9c2 memory 9b4 average Value calculator 100, 100a, 100b Lighting device 200, 200a, 200b Lighting fixture

Claims (16)

a rectifier circuit that rectifies an alternating voltage;
a PFC circuit that suppresses harmonics and improves the power factor;
a current control circuit that has a switching element and converts the output of the PFC circuit into a predetermined current value;
A control unit that controls the switching element,
The control unit
a calculation unit that detects the output current of the current control circuit and calculates a first control amount for feedback-controlling the output current to a predetermined target current;
a correction unit that calculates a second control amount that suppresses variations in the output current caused by pulsation of the output voltage of the PFC circuit in feedforward control;
a multiplication unit that outputs a multiplication result obtained by multiplying the first controlled variable and the second controlled variable;
The control unit changes the conduction time of the switching element according to the multiplication result,
The correction unit multiplies a difference between an instantaneous value of the output voltage and an average value of the output voltage by a larger coefficient to increase the second control amount as the amplitude of the AC voltage is smaller. A lighting device, wherein the second controlled variable is changed according to the magnitude of amplitude . The correction unit is characterized in that, when the instantaneous value of the output voltage is higher than the average value of the output voltage, the second control amount is calculated to shorten the conduction time of the switching element as compared with the immediately preceding control. The lighting device according to claim 1. The correction unit is characterized in that, when the instantaneous value of the output voltage is lower than the average value of the output voltage, the second control amount is calculated to lengthen the conduction time of the switching element as compared with the immediately preceding control. The lighting device according to claim 1 or 2. 4. The lighting device according to claim 2, wherein the correction unit uses the target value of the output voltage as the average value of the output voltage. 2. A timing at which the pulsation of the output voltage reaches a maximum value coincides with a timing at which the conduction time of the switching element reaches a minimum as a result of controlling the conduction time of the switching element by the control unit. 5. The lighting device according to any one of 4 to 4. 2. A timing at which the pulsation of the output voltage becomes a minimum value coincides with a timing at which the conduction time of the switching element becomes maximum as a result of controlling the conduction time of the switching element by the control unit. 6. The lighting device according to any one of 1 to 5. 7. The lighting device according to claim 1, wherein the rectifier circuit and the PFC circuit are composed of synchronous rectifier circuits. 7. The lighting device according to any one of claims 1 to 6, wherein the PFC circuit and the current control circuit are composed of DC conversion circuits. The lighting device according to any one of claims 1 to 8, wherein the switching element is made of a wide bandgap semiconductor. 10. The lighting device according to claim 9, wherein the wide bandgap semiconductor is silicon carbide, a gallium nitride-based material, or diamond. a rectifier circuit that rectifies an alternating voltage;
a PFC circuit that suppresses harmonics and improves the power factor;
a current control circuit that has a switching element and converts the output of the PFC circuit into a predetermined current value;
A control unit that controls the switching element,
The control unit
a calculation unit that detects the output current of the current control circuit and calculates a first control amount for feedback-controlling the output current to a predetermined target current;
a correction unit that calculates a second control amount that suppresses variations in the output current caused by pulsation of the output voltage of the PFC circuit in feedforward control;
a multiplication unit that outputs a multiplication result obtained by multiplying the first controlled variable and the second controlled variable;
The control unit changes the conduction time of the switching element according to the multiplication result,
The correction unit multiplies a difference between an instantaneous value of the output voltage and an average value of the output voltage by a larger coefficient to increase the second control amount as the amplitude of the AC voltage is smaller. a lighting device that changes the second control amount according to the amplitude ;
and a light source that is lit by the lighting device. 12. The lighting fixture according to claim 11, wherein the light source is an LED or an organic EL connected to the lighting device. detecting the output current of a current control circuit that has a switching element and converts the output of the PFC circuit into a predetermined current value;
calculating a first controlled variable for feedback-controlling the output current to a predetermined target current;
calculating a second control amount that suppresses fluctuations in the output current caused by pulsation of the output voltage of the PFC circuit connected to the rectifier circuit in feedforward control;
changing the conduction time of the switching element according to the multiplication result obtained by multiplying the first controlled variable and the second controlled variable;
The smaller the amplitude of the AC voltage input to the rectifier circuit, the larger the difference between the instantaneous value of the output voltage and the average value of the output voltage is multiplied by a larger coefficient to increase the second control amount, thereby increasing the AC voltage. and changing the second control amount according to the magnitude of the amplitude of the lighting device. calculating the second control amount that shortens the conduction time of the switching element compared to the immediately preceding control when the instantaneous value of the output voltage is higher than the average value of the output voltage;
14. The method according to claim 13, further comprising: calculating the second control amount that lengthens the conduction time of the switching element compared to the previous control when the instantaneous value of the output voltage is lower than the average value of the output voltage. lighting device control method. detecting the output current of a current control circuit that has a switching element and converts the output of the PFC circuit into a predetermined current value;
calculating a first controlled variable for feedback-controlling the output current to a predetermined target current;
calculating a second control amount that suppresses fluctuations in the output current caused by pulsation of the output voltage of the PFC circuit connected to the rectifier circuit in feedforward control;
changing the conduction time of the switching element according to the multiplication result obtained by multiplying the first controlled variable and the second controlled variable;
The second control amount is increased by multiplying the difference between the instantaneous value of the output voltage and the average value of the output voltage by a larger coefficient as the amplitude of the AC voltage input to the rectifier circuit is smaller. How to control the device. lighting a light source with the output current;
16. The method according to any one of claims 13 to 15, wherein the average value of the output current is brought closer to the maximum rated current of the light source compared to the case where the conduction time of the switching element is changed based only on the first controlled variable. The control method of the lighting device according to any one of the items.

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