Power supply and lighting equipment

Abstract

To provide a power supply unit that can control the wave height value appropriately according to the load.SOLUTION: A conversion circuit 23 has a first switching element Q1 and converts input power by switching the first switching element Q1 to supply the light source 14. The control unit 24 determines the duty ratio of switching of the first switching element Q1 and controls the wave height according to the maximum duty ratio of switching of the first switching element Q1, which is preset according to the light source 14, and the peak current of the output current of the conversion circuit 23.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power supply device and a lighting device that perform peak value control. [Background technology]

[0002] Conventionally, for example, a power supply device used in a lighting device is equipped with a conversion circuit that converts input power by switching a switching element and supplies it to a light source, which is a load, and is known to determine the switching duty ratio of the switching element according to the peak current of the output current of this conversion circuit, thereby controlling the peak value.

[0003] In a power supply device that controls peak values, the voltage and current of a light source differ depending on the type of light source connected to the power supply device, and it is therefore desirable to be able to perform appropriate peak value control depending on the light source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-57257 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a power supply device and a lighting device capable of controlling a peak value appropriately according to a load. [Means for solving the problem]

[0006] A power supply device according to an embodiment includes a conversion circuit and a control unit. The conversion circuit has a switching element, converts input power by switching the switching element, and supplies the converted power to a load. The control unit determines a duty ratio of the switching element according to a maximum duty ratio of the switching element that is preset according to the load and a peak current of an output current of the conversion circuit, and controls a peak value.The control unit detects the output current of the conversion circuit, changes the switching duty ratio of the switching element so that the detected value of the output current of the conversion circuit matches a predetermined target value, and sets a maximum duty ratio from the switching duty ratio of the switching element at which the detected value of the output current of the conversion circuit matches the target value. Effect of the Invention

[0007] According to the power supply device of the embodiment, appropriate peak value control according to the load can be performed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a circuit diagram of a power supply device according to an embodiment; [Diagram 2] 4 is a flowchart showing a setting process for setting a maximum duty ratio of switching of a switching element according to a load performed by the power supply device; [Diagram 3] FIG. 4 is a waveform diagram of the output current of the conversion circuit of the power supply device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings.

[0010] Fig. 1 shows a lighting device 10 which is a load device. The lighting device 10 is used, for example, for lighting on a stage or in a studio, and is controlled by a control device 11 such as a dimmer console which is a higher-level device connected in a communicable manner. The lighting device 10 is compatible with, for example, full-color lighting.

[0011] The lighting device 10 includes a light source module 15 having a light source 14 as a load, and a power supply device 16 to which the light source module 15 is connected and which turns on the light source 14.

[0012] The light source 14 includes an LED 18 that is a light-emitting element. A plurality of LEDs 18 are used in the light source module 15. When the lighting device 10 is compatible with full-color lighting, the LEDs 18 that emit different light colors of at least red, green, and blue are used. The LEDs 18 have different voltages (forward voltages) for each light color, and the light source module 15 that is the light source 14 that uses a plurality of LEDs 18 has different voltages and currents for each light color. The light source 14 is not limited to the LED 18, and other solid-state light-emitting elements such as organic electroluminescence (EL) may be used.

[0013] The LEDs 18 of different light colors are connected to a power supply device 16 for each light color and controlled individually. Although Fig. 1 shows a case where the LEDs 18 of one light color are connected to one power supply device 16, part of the power supply device 16 may be shared by the LEDs 18 of different light colors.

[0014] In addition, the power supply device 16 has a pair of input terminals of a rectifier circuit 20 connected to a commercial AC power source e, which is an external power source that supplies input power of AC 100V, via a filter circuit (not shown). The rectifier circuit 20 rectifies AC power from the commercial AC power source e into DC power and outputs it. A first conversion circuit 21 is connected to a pair of output terminals of the rectifier circuit 20. The first conversion circuit 21 is a known power factor correction circuit for power factor correction, and is a boost chopper circuit in this embodiment. The first conversion circuit 21 converts the voltage of the DC power input from the rectifier circuit 20 into a predetermined first DC constant voltage that is higher than the voltage and outputs it.

[0015] The second conversion circuit 22 is connected to the output side of the first conversion circuit 21. The second conversion circuit 22 is a step-down chopper circuit that converts the first constant DC voltage input from the first conversion circuit 21 into a predetermined second constant DC voltage lower than the first constant DC voltage and outputs the second constant DC voltage.

[0016] The first conversion circuit 21 and the second conversion circuit 22 constitute a conversion circuit 23 that converts the input power and supplies it to the light source 14.

[0017] The second conversion circuit 22 includes a series circuit of a first switching element Q1 and a feedback diode D, which are switching elements connected between the output terminals of the first conversion circuit 21, and an inductor L, one end of which is connected to a connection point between the first switching element Q1 and the cathode of the feedback diode D. A control unit 24 constituted by a microcomputer is connected to a control terminal of the first switching element Q1 via a driver circuit DRV, and the first switching element Q1 is switched by a first PWM signal S1 output from the control unit 24. The first switching element Q1 is switched by the first PWM signal S1 at a predetermined operating frequency, for example, an operating frequency of 100 kHz or more, and is driven so that the valley of the output current IL flowing through the inductor L is larger than zero, and the output current IL flows continuously through the inductor L in a continuous current mode.

[0018] In addition, a dimming circuit 25 including a second switching element Q2 connected in parallel to an output end of the second conversion circuit 22 is connected, and an input end of the light source module 15 is also connected. The second switching element Q2 is connected in parallel to the light source 14 of the light source module 15. A control unit 24 is connected to a control terminal of the second switching element Q2, and the second switching element Q2 is switched by a second PWM signal S2 output from the control unit 24 in response to a dimming signal input from the control device 11.

[0019] The dimming circuit 25 shorts and opens the output terminals of the second conversion circuit 22 by switching the second switching element Q2, thereby controlling the current flowing through the light source 14. That is, the load current I, which is the average current flowing through the light source 14, is controlled by switching the output current IL of the conversion circuit 23 by the second switching element Q2.

[0020] In addition, in the second conversion circuit 22, a resistor R for detecting the output current IL is connected between the anode of the feedback diode D and the second switching element Q2 which is one output terminal.

[0021] A first current detection unit 26 that detects the peak current of the output current IL of the conversion circuit 23 when the control unit 24 controls the peak value is connected between the resistor R of the second conversion circuit 22 and the second switching element Q2, and a second current detection unit 27 that detects the output current IL of the conversion circuit 23 when the control unit 24 sets the maximum duty ratio of the switching of the first switching element Q1.

[0022] The first current detection unit 26 has a comparator 28, the inverting input terminal of which is connected between the resistor R of the second conversion circuit 22 and the second switching element Q2, and a threshold current (peak current value) Ith, which is a predetermined reference voltage, is input from a reference voltage source 29 to a non-inverting input terminal of the comparator 28. The comparator 28 compares the magnitude of the output current IL and the threshold current Ith based on the voltages corresponding to each of them. The output terminal of the comparator 28 is connected to the control unit 24, and the comparison result of the comparator 28 is input to the control unit 24 as a signal (voltage signal) S.

[0023] Unlike the first current detection unit 26, the second current detection unit 27 is connected between the resistor R of the second conversion circuit 22 and the light source 14. The second current detection unit 27 includes a detection circuit 30 that detects the output current IL of the conversion circuit 23 flowing to the light source 14 and outputs a detection signal, which is a voltage signal corresponding to the output current IL, to the control unit 24.

[0024] In addition, a voltage detection unit 31 that detects the output voltage of the conversion circuit 23, i.e., the voltage (load voltage) of the light source 14, is connected to the output terminal of the second conversion circuit 22. The voltage detection unit 31 includes a detection circuit 30 that detects the voltage of the light source 14 and outputs a detection signal thereof to the control unit 24.

[0025] The detection circuit 30 is used by both the second current detection unit 27 and the voltage detection unit 31, but the second current detection unit 27 and the voltage detection unit 31 may be provided separately without being used by both.

[0026] The control unit 24 has a function of setting a maximum duty ratio (maximum on-duty) of the switching of the first switching element Q1 according to the light source 14 connected to the conversion circuit 23. When setting this maximum duty ratio, the control unit 24 detects the output current IL of the conversion circuit 23 by the second current detection unit 27 while the output current IL is actually flowing to the light source 14 connected to the conversion circuit 23, compares the detected value of the output current IL of the conversion circuit 23 with a target value that is a preset target current value, changes the duty ratio of the switching of the first switching element Q1 so that the detected value of the output current IL of the conversion circuit 23 matches the target value, and sets and stores the maximum duty ratio from the duty ratio of the switching of the first switching element Q1 at which the detected value of the output current IL of the conversion circuit 23 matches the target value. The control unit 24 has a storage unit that stores a control program and the maximum duty ratio of the switching of the first switching element Q1. The maximum duty ratio of the switching of the first switching element Q1 is set, for example, in an inspection process before shipment from a factory, and may be set automatically when the power supply device 16 is first turned on, or may be set by inputting a predetermined signal to the control unit 24 after the power supply device 16 is turned on. In addition, the target value is set according to the setting of the peak current of the output current of the conversion circuit 23.

[0027] Furthermore, the control unit 24 has the function of determining the switching duty ratio of the first switching element Q1 based on the maximum duty ratio that is preset and stored in accordance with the light source 14 and the peak current of the output current IL of the conversion circuit 23, which is the comparison result of the comparator 28 of the first current detection unit 26, and outputting a first PWM signal S1 of this duty ratio to the first switching element Q1, thereby executing peak value control.

[0028] Furthermore, the control unit 24 has a function of determining the duty ratio of the second PWM signal S2 in response to the dimming signal input from the control device 11, outputting the second PWM signal S2 having this duty ratio to the second switching element Q2, and executing dimming control to control the current flowing through the light source 14.

[0029] Furthermore, the control unit 24 has a function of monitoring the output voltage of the conversion circuit 23 by the detection circuit 30 of the voltage detection unit 31, and executing a protective operation to reduce or stop the output of the conversion circuit 23 according to the output voltage.

[0030] In addition, when part of the power supply 16 is shared by the LEDs 18 of different light colors, a power supply circuit section for each light color (including the second conversion circuit 22, the dimming circuit 25, the control section 24, etc.) is connected in parallel to the contact 32 at the output end of the first conversion circuit 21 for each LED 18 of a different light color, and the LEDs 18 of different light colors are each connected to the power supply circuit section for each light color and controlled individually.

[0031] Next, the operation of this embodiment will be described.

[0032] First, the operation of the lighting device 10 will be described. When power is supplied to the power supply device 16 from a commercial AC power source e, in the conversion circuit 23, the first conversion circuit 21 operates to boost the AC input voltage to a first DC constant voltage, and the second conversion circuit 22 operates to step down the first DC constant voltage to a second DC constant voltage.

[0033] In the second conversion circuit 22, the first PWM signal S1 from the control unit 24 is input to a control terminal of the first switching element Q1, and the first switching element Q1 is switched in response to the first PWM signal S1. When the first switching element Q1 is in an on state, an output current IL1 is output from the second conversion circuit 22 through the inductor L from the first switching element Q1, and energy is stored in the inductor L. When the first switching element Q1 is in an off state, the energy stored in the inductor L by the output current IL1 is released, and an output current IL2 is output from the second conversion circuit 22 through the inductor L from the feedback diode D. Then, the output current IL (IL=IL1+IL2) flows continuously through the inductor L due to the switching of the first switching element Q1.

[0034] The control unit 24 determines the switching duty ratio of the first switching element Q1 based on the maximum duty ratio that is preset in accordance with the light source 14 and the peak current of the output current IL of the conversion circuit 23, which is the comparison result of the comparator 28 of the first current detection unit 26, and outputs a first PWM signal S1 of this duty ratio to the first switching element Q1 to control the peak value of the second conversion circuit 22.

[0035] Furthermore, the control unit 24 determines the duty ratio of the second PWM signal S2 in response to the dimming signal input from the control device 11, and outputs the second PWM signal S2 with this duty ratio to the second switching element Q2 of the dimming circuit 25. In the dimming circuit 25, the second switching element Q2 is switched on and off in response to the second PWM signal S2. By short-circuiting and opening the output terminals of the second conversion circuit 22 by switching the second switching element Q2, a load current I flows through the light source 14 in response to the dimming signal input from the control device 11, and the light source 14 is turned on at the set dimming level.

[0036] Furthermore, the control unit 24 monitors the output voltage of the conversion circuit 23 by the detection circuit 30 of the voltage detection unit 31, and executes a protective operation to reduce or stop the output of the conversion circuit 23 according to the output voltage.

[0037] Next, a setting process in which the control unit 24 sets the maximum duty ratio of the switching of the first switching element Q1 in accordance with the light source 14 connected to the conversion circuit 23 will be described with reference to the flowchart of FIG.

[0038] This process of setting the maximum duty ratio is performed automatically when the power supply device 16 is first turned on, for example, during an inspection process before shipment from the factory, or is performed by inputting a predetermined signal to the control unit 24 after the power supply device 16 is turned on.

[0039] The control unit 24 sets a target value of the output current IL of the conversion circuit 23 (step S1). This target value is set according to the setting of the peak current of the output current of the conversion circuit 23 that executes peak value control.

[0040] The control unit 24 starts switching of the first switching element Q1 of the conversion circuit 23 at a duty ratio in which the on-duty ratio is minimum or relatively small (step S2).

[0041] At this time, the second switching element Q2 of the dimming circuit 25 is maintained in the off state, so that the output current IL of the conversion circuit 23 flows entirely to the light source .

[0042] The output current IL flowing from the conversion circuit 23 to the light source 14 is detected by the second current detection unit 27 (step S3).

[0043] The control unit 24 acquires the output current IL of the conversion circuit 23 detected by the second current detection unit 27, and compares the detected value of the output current IL of the conversion circuit 23 with a preset target value to determine whether they match (step S4).

[0044] When the control unit 24 determines that the detected value does not match the target value, it changes the on-duty ratio to an increased duty ratio so that the detected value matches the target value (step S5), and switches the first switching element Q1 at this duty ratio.

[0045] When the control unit 24 determines that the detected value matches the target value, it sets the matched duty ratio as the maximum duty ratio of the switching of the first switching element Q1, and stores it in the storage unit of the control unit 24 (step S6).

[0046] In this way, in the power supply device 16, the switching duty ratio of the first switching element Q1 is determined in accordance with the maximum duty ratio that is preset in accordance with the light source 14 and the peak current of the output current IL of the conversion circuit 23, and peak value control is performed, thereby enabling appropriate peak value control in accordance with the light source 14.

[0047] Furthermore, in the power supply device 16, by actually passing a current through the light source 14 connected to the conversion circuit 23 and setting the maximum switching duty ratio of the first switching element Q1 of the conversion circuit 23 in accordance with the voltage characteristics of the light source 14, appropriate peak value control can be achieved even for light sources 14 with different voltage characteristics.

[0048] The LEDs, which are the light sources 14, have different voltage characteristics for each chip, and even for the same LED type, the voltage varies for each chip, so that the voltage characteristics vary when they are assembled into a module. In the step-down chopper circuit, which is the second conversion circuit 22, the switching duty is determined by the ratio of the input voltage to the output voltage (=LED voltage), so it is necessary to determine the duty according to the LED voltage. In particular, in a circuit that performs peak current control by fixed frequency switching, when the detection of the peak current by the comparator, which is the comparator 28, varies due to the influence of noise, the waveform of the output current of the step-down chopper circuit may become distorted, causing problems such as an increase in current ripple. In particular, when the on-duty exceeds 50%, if the duty becomes smaller than the original duty due to the variation in the detection of the peak current, the next period is compensated for, and the operation is likely to alternate between periods in which the duty becomes large and periods in which the duty becomes small. 3 shows the waveform of the output current of the conversion circuit 23 (step-down chopper circuit), where waveform A shown by a solid line is an ideal output current waveform, waveform B shown by a dashed line is an output current waveform when there is variation in the detection of the peak current as described above, and waveform C shown by a dashed line is an output current waveform when the maximum duty ratio is set and adjusted according to the LED as in this embodiment. Therefore, by setting a maximum duty according to the LED, even if the waveform is disturbed, operation is stabilized by operating within an appropriate duty range, and it is possible to suppress problems such as large current ripple.

[0049] In the case of a full-color lighting device 10, the voltage characteristics of the light source 14 differ for each light color, but since the maximum switching duty ratio of the first switching element Q1 of the conversion circuit 23 can be appropriately set according to the voltage characteristics of the light source 14 for each light color, appropriate peak value control can be performed for each light source 14 of each light color. Therefore, the power supply device 16 can be made common to the light sources 14 of each light color.

[0050] In addition, since the second current detection unit 27 is provided, which is different from the first current detection unit 26 that detects the peak current of the output current of the conversion circuit 23, the output current IL of the conversion circuit 23 flowing to the light source 14 can be detected by the second current detection unit 27, making it possible to set the maximum duty ratio.

[0051] In addition, since the setting of the peak current of the output current IL of the conversion circuit 23 can be changed, the target value can be changed in accordance with the change in this setting, and a maximum duty ratio can be set in accordance with the changed target value, thereby enabling appropriate crest value control in response to the change in the setting of the peak current of the output current IL of the conversion circuit 23.

[0052] Incidentally, in the control unit 24, instead of setting and storing in advance the maximum duty ratio according to the light source 14, the maximum rated voltage of the light source 14 may be set in advance and stored.

[0053] In this case, the control unit 24 determines the duty ratio of the switching of the first switching element Q1 according to a preset maximum rated voltage of the light source 14 and the peak current of the output current of the conversion circuit 23, and controls the peak value. At this time, the step-down ratio is calculated from the input voltage to the second conversion circuit 22, which is a step-down chopper circuit of the conversion circuit 23, and the maximum rated voltage of the light source 14, and therefore the maximum duty ratio of the switching of the first switching element Q1 is calculated according to this step-down ratio.

[0054] Furthermore, when setting the maximum rated voltage of the light source 14, the control unit 24 detects the output current of the conversion circuit 23, changes the switching duty ratio of the first switching element Q1 so that the detected value of the output current of the conversion circuit 23 matches a predetermined target value, and sets the maximum rated voltage of the light source 14 from the voltage of the light source 14 detected by the voltage detection unit 31 when the detected value of the output current of the conversion circuit 23 matches the target value.

[0055] In this way, even if the maximum rated voltage of the light source 14 is preset and stored, appropriate peak value control can be performed for light sources 14 having different voltage characteristics.

[0056] Furthermore, the storage of the maximum duty ratio is not limited to storing it in the storage unit of the control unit 24, and when the lighting device 10 is connected to the control device 11, information on the maximum duty ratio may be transferred to the control device 11 and stored in the control device 11. In this case, when the lighting device 10 is started up, information on the stored maximum duty ratio may be transmitted from the control device 11 to the lighting device 10.

[0057] Moreover, the power supply device 16 may not necessarily include the dimming circuit 25 as long as it includes the conversion circuit 23 that executes peak value control.

[0058] Furthermore, the load connected to the conversion circuit 23 is not limited to the light source 14, but may be any load that operates with the power converted by the peak value control of the conversion circuit 23.

[0059] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0060] 10. Lighting Equipment 14 Light source as load 16 Power supply 23 Conversion circuit 24 Control Unit 26 First current detection section 27 Second current detection section 31 Voltage detection section Q1 is the first switching element

Claims

1. a conversion circuit having a switching element, converting input power by switching the switching element and supplying the converted power to a load; a control unit that determines a duty ratio of the switching of the switching element in accordance with a maximum duty ratio of the switching of the switching element that is preset in accordance with the load and a peak current of an output current of the conversion circuit, and controls a peak value; Equipped with The control unit detects an output current of the conversion circuit, changes a switching duty ratio of the switching element so that the detected value of the output current of the conversion circuit coincides with a preset target value, and sets the maximum duty ratio from the switching duty ratio of the switching element at which the detected value of the output current of the conversion circuit coincides with the target value. A power supply device comprising:

2. a first current detection unit that detects a peak current of an output current of the conversion circuit; a second current detection unit different from the first current detection unit and configured to detect an output current of the conversion circuit; Further equipped with The control unit is During the peak value control, a peak current of the output current of the conversion circuit detected by the first current detection unit is obtained and a peak value is controlled; When setting the maximum duty ratio, the output current of the conversion circuit detected by the second current detection unit is acquired to set the maximum duty ratio.

2. The power supply device according to claim 1.

3. The control unit is capable of changing a setting of a peak current of the output current of the conversion circuit, changes the target value in response to a change in the setting of the peak current of the output current of the conversion circuit, and sets the maximum duty ratio in response to the changed target value.

3. The power supply device according to claim 1 or 2.

4. a conversion circuit having a switching element, converting input power by switching the switching element and supplying the converted power to a load; a control unit that determines a duty ratio of the switching of the switching element according to a preset maximum rated voltage of the load and a peak current of an output current of the conversion circuit, and controls a peak value; A power supply device comprising:

5. A voltage detection unit that detects a voltage of the load is further provided. The control unit detects an output current of the conversion circuit, changes a switching duty ratio of the switching element so that a detected value of the output current of the conversion circuit coincides with a preset target value, and sets a maximum rated voltage of the load from a voltage of the load detected by the voltage detection unit when the detected value of the output current of the conversion circuit coincides with the target value.

5. The power supply device according to claim 4.

6. A light source as a load; A power supply device according to any one of claims 1 to 5; A lighting device comprising:

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