JP2021048760A - Power supply device and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device capable of reducing power loss due to generation of a control power source of a ripple current reduction circuit. A rectifier circuit 19 rectifies an AC voltage. The power conversion circuit 20 has at least a switching element Q1 and an inductor L2 connected to the switching element Q1, converts the voltage rectified by the rectifier circuit 19 into a DC voltage, and supplies the voltage to the light source 11. The ripple current reduction circuit 21 is connected in series with the light source 11 to keep the current flowing through the light source 11 constant. The control unit 22 inputs the detection voltage at the connection point between the light source 11 and the ripple current reduction circuit 21, and feedback-controls the switching element Q1 of the power conversion circuit 20. The control power generation unit 23 has a secondary winding L3 magnetically coupled to the inductor L2 of the power conversion circuit 20, and supplies the control power induced by the secondary winding L3 to the ripple current reduction circuit 21. .. [Selection diagram] Fig. 1

Description

An embodiment of the present invention relates to a power supply device that supplies a DC voltage to a light source, and a lighting device that uses the power supply device.

Conventionally, there is a power supply device that converts an AC voltage into a DC voltage by a power conversion circuit and supplies it to a light source, and also detects a voltage flowing through the light source to feed-back control the power conversion circuit. In this power supply device, a ripple current reduction circuit may be connected in series with the light source in order to keep the current flowing through the light source constant. The control power supply required for the ripple current reduction circuit to operate may be taken out from the output side of the power conversion circuit and supplied.

When the control power supply of the ripple current reduction circuit is taken out from the output side path of the power conversion circuit and supplied, the DC voltage taken out from the output side path of the power conversion circuit is adjusted to the voltage value of the control power supply supplied to the ripple current reduction circuit. It is necessary, and a circuit configuration for this adjustment is required, and power loss occurs at the time of adjustment, that is, at the time of generating a control power supply.

Japanese Patent No. 5110197

An object of the present invention is to provide a power supply device and a lighting device capable of reducing power loss due to generation of a control power source of a ripple current reduction circuit with a simple configuration.

The power supply device of the embodiment includes a rectifier circuit, a power conversion circuit, a ripple current reduction circuit, a control unit, and a control power supply generation unit. The rectifier circuit rectifies the AC voltage. The power conversion circuit has at least a switching element and an inductor connected to the switching element, and converts the voltage rectified by the rectifier circuit into a DC voltage and supplies it to the light source. The ripple current reduction circuit is connected in series with the light source to keep the current flowing through the light source constant. The control unit inputs the detection voltage at the connection point between the light source and the ripple current reduction circuit, and feedback-controls the switching element of the power conversion circuit. The control power generation unit has a secondary winding magnetically coupled to the inductor of the power conversion circuit, and supplies the control power induced by the secondary winding to the ripple current reduction circuit.

According to the power supply device of the embodiment, it can be expected that the power loss due to the generation of the control power supply of the ripple current reduction circuit can be reduced by a simple configuration.

It is a circuit diagram of the power supply device which shows 1st Embodiment. It is a circuit diagram of the power supply device which shows the 2nd Embodiment.

Hereinafter, the first embodiment will be described with reference to FIG.

The lighting device 10 includes a light source 11 and a power supply device 12 that supplies DC power to the light source 11.

As the light source 11, for example, an LED which is a semiconductor light emitting element is used. In addition to the LED, the light source 11 may use another semiconductor light emitting element such as an EL. Further, the light source 11 may be integrated with the power supply device 12, for example, or may be configured as a light source unit that can be attached to and detached from the fixture body, and the power supply device 12 is charged with electricity when the light source unit is attached to the fixture body. It may be configured to be connected as a target.

Then, the power supply device 12 makes the rectifier circuit 19 that rectifies the AC voltage, the power conversion circuit 20 that converts the voltage rectified by the rectifier circuit 19 into a DC voltage and supplies it to the light source 11, and the current flowing through the light source 11 constant. Ripple current reduction circuit 21, control unit 22 that feedback-controls the power conversion circuit 20, control power generation unit 23 that supplies control power to the ripple current reduction circuit 21 and control unit 22, and power supply for starting when the power supply device 12 is started. Is provided with a power generation unit 24 for starting up to supply the control unit 22.

The rectifier circuit 19 has a pair of input ends connected to an AC power source e, which is an external power source. The rectifier circuit 19 rectifies the AC voltage input from the AC power supply e, and outputs the rectified voltage (DC voltage) from the pair of output terminals. The rectifier circuit 19 is, for example, a diode bridge full-wave rectifier in which four rectifier elements are combined. The rectifier circuit 19 may be a half-wave rectifier or the like. Further, the rectified voltage may be a full-wave rectified pulsating current or a half-wave rectified pulsating current.

Further, the power conversion circuit 20 is a Sepic (SEPIC: Single Ended Primary Inductance Converter) circuit, which is a one-converter type conversion circuit having a power factor improving circuit function and a DC / DC converter circuit function.

The power conversion circuit 20 has a capacitor (input side capacitor) C1 connected to a pair of output ends of the rectifier circuit 19. A series circuit of an inductor (first inductor) L1 and a switching element Q1 such as a field effect transistor is connected to both ends of the capacitor C1. Further, a series circuit of a capacitor C2 and an inductor (second inductor) L2 is connected to both ends of the switching element Q1. The inductor L1 and the inductor L2 are connected in series via a coupling capacitor C2. Since the inductor L2 is connected in parallel with the series circuit of the light source 11 and the ripple current reduction circuit 21, the voltage value is the same as the DC voltage supplied to the light source 11.

A diode D1 for preventing backflow and a capacitor (output side capacitor) C3 such as an electrolytic capacitor are connected to both ends of the inductor L2. In the diode D1, the anode is connected to the connection point between the capacitor C2 and the inductor L2, and the cathode is connected to the capacitor C3.

A series circuit of the light source 11 and the ripple current reduction circuit 21 is connected to both ends of the capacitor C3. The capacitor C3 is connected in parallel with the series circuit of the light source 11 and the ripple current reduction circuit 21 on the output side of the power conversion circuit 20.

Further, the ripple current reduction circuit 21 is connected in series with the light source 11 on the output side (output end) of the power conversion circuit 20. The ripple current reduction circuit 21 includes a variable impedance element Q2 connected in series with the light source 11 on the output side of the power conversion circuit 20, a detection resistor R1 which is a current detection unit, and a detection current detected via the detection resistor R1. The error amplifier 27 that controls the variable impedance element Q2 so that the value becomes a predetermined value is provided. When the light source 11 is an LED, the ripple current reduction circuit 21 is connected in series with the cathode side of the LED.

As the variable impedance element Q2, for example, a switching element such as a field effect transistor is used. The variable impedance element Q2 may use a variable resistor or the like that can continuously change the impedance.

The detection resistor R1 converts the current flowing through the light source 11 into a voltage signal (detection voltage) and outputs it to the error amplifier 27. As the current detection unit, for example, a current transformer or the like may be used in addition to the detection resistor R1.

In the error amplifier 27, the inverting input terminal is connected to the connection point between the variable impedance element Q2 and the detection resistor R1, and the non-inverting input terminal is connected to the reference voltage V1. Then, the error amplifier 27 compares the detection voltage corresponding to the ripple current detected by the detection resistor R1 with the reference voltage V1 and reduces the impedance when the detection voltage is smaller than the reference voltage V1. By controlling Q2 and controlling the variable impedance element Q2 so that the impedance is increased when the detected voltage is larger than the reference voltage V1, the ripple current is reduced and the current flowing through the light source 11 is kept constant. Works on.

Further, the control unit 22 is composed of, for example, a control IC or the like. The control unit 22 inputs the detection voltage from the connection point between the light source 11 and the ripple current reduction circuit 21, and switches the switching element Q1 so that the voltage applied to the ripple current reduction circuit 21 becomes a predetermined voltage value. Feedback control.

Further, the control power generation unit 23 has a secondary winding L3 that is magnetically coupled to the inductor L2 of the power conversion circuit 20. In the secondary winding L3, a control power supply having a voltage corresponding to the turns ratio of the inductor L2 and the secondary winding L3 is generated. The secondary winding L3 may be configured by one transformer together with the inductor L1 and the inductor L2 of the power conversion circuit 20, or is configured to be magnetically coupled to the inductor L2 as a separate configuration from the inductor L1. You may.

A diode D2 and a capacitor C4 such as an electrolytic capacitor are connected in series to one end of the secondary winding L3 on the high potential side, and the other end of the secondary winding L3 and the capacitor C4 are connected to the low potential side of the power conversion circuit 20. Has been done. The diode D2 has an anode connected to one end of the secondary winding L3 and a cathode connected to the capacitor C4. The connection point between the cathode of the diode D2 and the capacitor C4 is connected to the error amplifier 27 and the control unit 22 of the ripple current reduction circuit 21.

The control power supply induced in the secondary winding L3 is supplied to the error amplifier 27 and the control unit 22 of the ripple current reduction circuit 21 from the connection point between the cathode of the diode D2 and the capacitor C4. The voltage of the control power supply can be arbitrarily adjusted by the turns ratio of the inductor L2 and the secondary winding L3. Therefore, the turns ratio between the inductor L2 and the secondary winding L3 is adjusted so that the voltage of the predetermined control power supply is induced in the secondary winding L3 according to the DC voltage supplied to the light source 11.

Further, in the starting power generation unit 24, a series circuit of a resistor R2 and a capacitor C5 is connected to both ends of the capacitor C1, and a Zener diode ZD1 is connected in parallel with the capacitor C5. In the Zener diode ZD1, the cathode is connected to the connection point between the resistor R2 and the capacitor C5, and the anode is connected between the capacitor C1 and the capacitor C5. The power input terminals of the control unit 22 are connected to both ends of the Zener diode ZD1. Then, in the starting power generation unit 24, when the power supply device 12 is started (starting) by turning on the power, the DC voltage limited through the resistor R2 is used as a constant voltage starting power by the capacitor C5 and the Zener diode ZD1. This starting power is supplied to the control unit 22.

Further, a control power generation unit 23 is connected to the power input terminal of the control unit 22 via a diode D3. In the diode D3, the anode is connected to the control power generation unit 23, and the cathode is connected to the power input terminal of the control unit 22. The diode D3 prevents the starting power generated by the starting power generation unit 24 from flowing to the ripple current reduction circuit 21 when the power supply device 12 is started, and controls generated by the control power generation unit 23. When the power supply becomes high, it functions to supply this control power supply to the control unit 22.

Then, when the AC power supply e is turned on to the power supply device 12, the starting power generated by the starting power generation unit 24 is supplied to the control unit 22, and the control unit 22 operates. The control unit 22 controls the switching element Q1 on and off to operate the power conversion circuit 20, converts the voltage rectified by the rectifier circuit 19 into a DC voltage, and supplies the voltage to the light source 11.

In the power conversion circuit 20, when the switching element Q1 is turned on, a current flows through the paths of the capacitor C1, the inductor L1, the switching element Q1, and the capacitor C1, and energy (magnetic energy) is stored in the inductor L1. Further, a current flows through the path of the capacitor C2, the switching element Q1, the inductor L2, and the capacitor C2, and energy (magnetic energy) is stored in the inductor L2.

When the switching element Q1 is turned off, an electromotive force is generated in the inductor L1, and current flows in the paths of the inductor L1, the capacitor C2, the diode D1, the capacitor C3, the capacitor C1, and the inductor L1 to charge the capacitors C2 and C3. Further, an electromotive force is generated in the inductor L2, and a current flows through the paths of the inductor L2, the diode D1, the capacitor C3, and the inductor L2 to charge the capacitor C3.

Therefore, the input voltage is stepped up and down by turning the switching element Q1 on and off, a predetermined DC voltage is generated between both ends of the capacitor C3, and this DC voltage is supplied to the light source 11, so that the light source 11 is turned on.

Further, the control unit 22 inputs the detection voltage from the connection point between the light source 11 and the ripple current reduction circuit 21, and the switching element Q1 so that the voltage applied to the ripple current reduction circuit 21 becomes a predetermined voltage value. Feedback control of switching operation.

Further, in the ripple current reduction circuit 21 connected in series with the light source 11, the detection voltage corresponding to the ripple current detected by the detection resistor R1 by the error amplifier 27 is compared with the reference voltage V1, and the detection voltage is the reference voltage V1. By controlling the variable impedance element Q2 so as to reduce the impedance when it is smaller than, and by controlling the variable impedance element Q2 so as to increase the impedance when the detected voltage is larger than the reference voltage V1. It operates so as to reduce the ripple current and keep the current flowing through the light source 11 constant.

By these controls, a constant DC voltage and a constant current are supplied to the light source 11, and the light source 11 is lit stably.

Further, a control voltage is induced in the secondary winding L3 of the control power generation unit 23 magnetically connected to the inductor L2 of the power conversion circuit 20, and this control voltage is supplied to the error amplifier 27 of the ripple current reduction circuit 21. , The error amplifier 27 operates. Further, when the control power supply induced in the secondary winding L3 of the control power supply generation unit 23 becomes higher than a predetermined voltage value after startup, the control power supply from the control power supply generation unit 23 is supplied to the control unit 22 for control. Part 22 operates.

By the way, for example, when the control power supply of the ripple current reduction circuit 21 is taken out from the output side path of the power conversion circuit 20 (for example, the output side path between the capacitor C3 and the light source 11) and supplied, the output side of the power conversion circuit 20 It is necessary to adjust the DC voltage taken out from the path to the voltage value of the control power supply supplied to the ripple current reduction circuit 21, and a circuit configuration for this adjustment is required, and at the time of adjustment, that is, when the control power supply is generated. Power loss will occur.

In the present embodiment, the control voltage induced in the secondary winding L3 magnetically connected to the inductor L2 of the power conversion circuit 20 is supplied to the ripple current reduction circuit 21, so that the ripple current reduction circuit has a simple configuration. The power loss due to the generation of 21 control power sources can be reduced.

Moreover, since the inductor L2 is connected in parallel with the series circuit of the light source 11 and the ripple current reduction circuit 21 and has the same voltage value as the DC voltage supplied to the light source 11, the inductor L2 and the secondary winding L3 By appropriately adjusting the turns ratio of, the voltage of a predetermined control power supply can be induced in the secondary winding L3 according to the DC voltage supplied to the light source 11, and the control power supply is generated with a small power loss. can do.

Further, since the control power supply generation unit 23 supplies the control power supply to the ripple current reduction circuit 21 and the control unit 22, the ripple current reduction circuit 21 and the control unit 22 can share the control power supply, and the configuration can be simplified.

Next, FIG. 2 shows a second embodiment.

A detection voltage adjusting unit 30 is provided in the middle of a path for sending the detection voltage at the connection point between the light source 11 and the ripple current reduction circuit 21 to the control unit 22. That is, the input end of the detection voltage adjustment unit 30 is connected to the connection point between the light source 11 and the ripple current reduction circuit 21, and the output end of the detection voltage adjustment unit 30 is connected to the control unit 22. The detection voltage adjustment unit 30 operates by inputting a control power supply from the control power supply generation unit 23. The other configurations and effects are the same as those in the first embodiment.

The detection voltage adjustment unit 30 has a detection voltage stop adjustment function that stops the input of the detection voltage to the control unit 22 until the control power generated by the control power generation unit 23 rises to a predetermined value (voltage value), or It has one of the detection voltage drop adjustment functions that lowers the detection voltage input to the control unit 22 until the control power generated by the control power generation unit 23 rises to a predetermined value (voltage value). There is. It has a function of a control voltage determination unit that determines whether or not the control power source generated by the control power supply generation unit 23 has risen to a predetermined value.

By the way, when the AC power supply e is turned on to the power supply device 12, the control unit 22 is activated by the start power generation unit 24 to start the operation of the power conversion circuit 20, but the control power supply generated by the control power generation unit 23 is started. The ripple current reduction circuit 21 does not operate until the value rises to a predetermined value. Therefore, the detection voltage input to the control unit 22 from the connection point between the light source 11 and the ripple current reduction circuit 21 becomes high, and the control unit 22 controls so as to reduce or stop the operation of the power conversion circuit 20 to reduce or stop the operation of the light source 11. Lighting may be delayed or may not light.

In the present embodiment, the detection voltage adjusting unit 30 stops the input of the detection voltage to the control unit 22 or stops the input of the detection voltage to the control unit 22 until the control power generated by the control power generation unit 23 rises to a predetermined value. In order to reduce the detection voltage input to, the control unit 22 determines that the detection voltage is 0 or low, and operates the power conversion circuit 20 so that the output voltage becomes high. Therefore, due to the operation of the power conversion circuit 20, the control voltage generated by the control power generation unit 23 rises to a predetermined value, and this control voltage is supplied to the ripple current reduction circuit 21 to operate the ripple current reduction circuit 21. , The light source 11 can be turned on.

Further, in order to supply the control power supply to the ripple current reduction circuit 21, the control unit 22, and the detection voltage adjustment unit 30, the control power generation unit 23 is shared by the ripple current reduction circuit 21, the control unit 22, and the detection voltage adjustment unit 30. It can be done and the configuration can be simplified.

The power conversion circuit is not limited to the sepic circuit, and if it is possible to convert at least a voltage obtained by rectifying an AC voltage using a switching element and an inductor into a DC voltage supplied to a light source, for example, a flyback converter or the like. Other circuit configurations may be used.

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 embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

10 Lighting equipment
11 Light source
12 Power supply
19 Rectifier circuit
20 Power conversion circuit
21 Ripple current reduction circuit
22 Control unit
23 Control power generator
30 Detected voltage adjuster
L2 inductor
L3 secondary winding
Q1 Switching element

Claims (4)

With a rectifier circuit that rectifies AC voltage;
A power conversion circuit that has at least a switching element and an inductor connected to this switching element, converts the voltage rectified by the rectifier circuit into a DC voltage, and supplies it to the light source.
With a ripple current reduction circuit that is connected in series with the light source and keeps the current flowing through the light source constant;
A control unit that inputs the detection voltage at the connection point between the light source and the ripple current reduction circuit and feedback-controls the switching element of the power conversion circuit;
A control power generation unit having a secondary winding magnetically coupled to the inductor of the power conversion circuit and supplying a control power source induced by the secondary winding to the ripple current reduction circuit;
A power supply device characterized by being provided with. The power supply device according to claim 1, further comprising a detection voltage adjusting unit that stops the input of the detection voltage to the control unit until the control power source generated by the control power generation unit rises to a predetermined value. .. The power supply according to claim 1, further comprising a detection voltage adjusting unit that lowers the detection voltage input to the control unit until the control power source generated by the control power generation unit rises to a predetermined value. apparatus. With a light source;
The power supply device according to any one of claims 1 to 3, which supplies a DC voltage to the light source;
A lighting device characterized by being provided with.

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