TWI672975B - Light-emitting element driving device and driving method thereof - Google Patents

Abstract

The present disclosure relates to a light emitting device driving device including an energy storage device, a power source, and a power conversion circuit. The power source is electrically connected to the energy storage element via the light emitting element to provide current to the light emitting element and to charge the energy storage element. The power conversion circuit is electrically connected to the power source and the energy storage component, and includes an inductor. The energy storage component charges the inductor when the power conversion circuit is in the first operational state. When the power conversion circuit is in the second operational state, the inductor is discharged to the power source.

Description

Light-emitting element driving device and driving method thereof

The present disclosure relates to a driving device, and more particularly to a high efficiency converting device that processes a portion of an energy load to drive a light emitting device driving device of a light emitting element.

A light-emitting diode (LED) is a current-driven light-emitting device that adjusts the brightness of light by controlling the current flowing through the LED. In the prior art, when the LED is connected to a DC voltage source for operation, the LED operating current is regulated by a series resistor. The advantage of this circuit is that the circuit is simple, and the disadvantage is low efficiency. Another prior art, the adjustment of the LED current through the power converter, has the advantage of higher efficiency than the aforementioned series resistor, but since the LED load is completely through the power converter, and if it is connected to the AC mains application, With the addition of a power factor correction circuit, the overall efficiency of the system cannot be further improved under the secondary circuit architecture.

When designing the driving device of the LED, the factors to be considered include the complexity of the circuit structure, the conversion efficiency and the stability of the current, and how to take into account the above various factors is an important issue at present.

One aspect of the present disclosure relates to a light-emitting device driving device including an energy storage device, a power source, and a power conversion circuit. The positive terminal of the energy storage device is directly connected to the light-emitting device. The power source is electrically connected to the positive terminal of the energy storage component via the light emitting component for providing current to the light emitting component and for charging the energy storage component. The power conversion circuit is electrically connected to the power source and the energy storage component, wherein the power conversion circuit includes an inductor. The energy storage component charges the inductor in a first operational state of the power conversion circuit, and the electrical discharge is discharged to the power source in a second operational state of the power conversion circuit.

Another aspect of the present disclosure is directed to a method of driving a light-emitting element, comprising the steps of: supplying a current to a light-emitting element through a power source, and charging the energy storage element. The power source is electrically connected to the first end of the light emitting element, and the positive end of the energy storage element is directly connected to the second end of the light emitting element. In the case where the power source continuously supplies the current to the light-emitting element, the first switching element is turned on, the energy storage element charges the inductor, the first switching element is turned off, and the inductor is discharged to the power source.

Still another aspect of the present disclosure relates to a light emitting device driving apparatus including an energy storage element, a power source, an inductor, a first switching element, and a second switching element. The power source is connected to the positive terminal of the energy storage component via the light emitting element, and the power source is used to supply current to the light emitting component and to charge the energy storage component. The inductor is electrically connected to the energy storage component. The first switching element is electrically connected to the energy storage element and the inductor, wherein the energy storage element is used to charge the inductor when the first switching element is turned on. The second switching element is electrically connected to the inductor and the power source, wherein when the first switching element is turned off, the inductor is discharged to the power source through the second switching element.

The embodiments of the present disclosure are disclosed in the following drawings, and for the sake of clarity, the details of the invention are described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not necessary. In addition, some of the conventional structures and elements are shown in the drawings in a simplified schematic manner in order to simplify the drawings.

As used herein, when an element is referred to as "connected" or "coupled", it may mean "electrically connected" or "electrically coupled". "Connected" or "coupled" can also be used to indicate that two or more components operate or interact with each other. In addition, although the terms "first", "second", and the like are used herein to describe different elements, the terms are used to distinguish the elements or operations described in the same technical terms. The use of the term is not intended to be a limitation or a

Regarding the driving device of the LED, it is conventional to connect a resistor in series with the LED as a power converter to have a constant current on the LED. The advantage of this method is that the circuit is simple, the disadvantage is that the efficiency is low, and the resistance adjustment needs to be performed according to the LED specifications. To improve efficiency, many improved power converters have been designed. Common power converter types include Buck Converter, Boost Converter, and Buck-Boost Converter, but there are still improvements in efficiency. Space.

Please refer to FIG. 1 , which is a partial embodiment of the light-emitting element driving device 100 in the present disclosure. The light emitting device driving device 100 includes an energy storage device C1, a power source 110, and a power conversion circuit 130. The positive terminal of the energy storage component C1 is directly connected to the negative terminal of the at least one light emitting component 120. The power source 110 is connected to the energy storage element C1 via the light emitting element 120 for providing the first current I1 to the light emitting element 120 and for charging the energy storage element C1. In some embodiments, the light emitting element 120 and the energy storage element C1 are connected in series with each other, and the series branch of the light emitting element 120 and the energy storage element C1 are connected in parallel with the power source 110. In particular, the power source 110 of FIG. 1 is merely a schematic diagram, and those skilled in the art will appreciate that any power source that can provide power to the light-emitting component can be referred to as the power source 110. In some embodiments, the energy storage device C1 includes a capacitor, such as an aluminum capacitor, a metalized film capacitor, a multilayer ceramic capacitor, or other types of capacitors, and the light-emitting device 120 includes LEDs, but is not limited thereto.

The power conversion circuit 130 is electrically connected to the power source 110 and the energy storage element C1. The power conversion circuit 130 includes at least an inductance L1. When the power conversion circuit 130 is in the first operational state, the energy storage element C1 charges the inductance L1. When the power conversion circuit 130 is in the second operational state, the inductor L1 is discharged to the power source 110 to implement the function of energy-recycling.

The principle of the present disclosure is charged and discharged repeatedly by controlling the inductor L1, so that the energy of the energy storage element C1 is transmitted through the inductor L1 and is recharged to the power source 110. Accordingly, the voltage across the energy storage element C1 is controlled, thereby stabilizing the voltage across the light-emitting element 120 and the magnitude of the first current I1.

The circuit architecture used in the present disclosure is such that the output of the power supply 110 is connected in parallel to the series branch of the light emitting element 120 and the energy storage element C1. Under this circuit architecture, "V ₁₁₀ = V ₁₂₀ + V _C1 " is formed on the driving device 100. Wherein, the voltage across the power source 110 (V ₁₁₀ ) is equal to the sum of the voltage across the light-emitting element 120 and the energy storage element C1. In the present disclosure, since the power conversion circuit 130 only needs to process part of the load energy and has a discharge recharge, the drive device 100 has better conversion efficiency than the conventional power converter. In particular, when the power supply 110 is the output of another stage of conversion circuitry for powering the light emitting elements 120, the overall conversion efficiency that can be improved by the present disclosure will be more apparent.

In some embodiments, the power source 110 includes an AC voltage source 111, an adjustment circuit 112, and an input capacitor C2. The adjusting circuit 112 is electrically connected to the AC voltage source 111 for receiving an AC voltage generated by the AC voltage source 111 and outputting a regulated voltage. In some embodiments, the adjustment circuit 112 is a Power Factor Correction (PFC), a High Voltage Direct Current (HVDC), or a bridge rectifier. In some embodiments, the power source 110 can also be a battery. The input capacitor C2 is electrically connected to the output of the adjusting circuit 112 for receiving the regulated voltage, and supplies power to the light emitting element 120 and the energy storage element C1 to provide the first current I1 to the light emitting element 120. In some embodiments, the input capacitor C2 is connected in parallel with the series branch of the light-emitting element 120 and the energy storage element C1, and is configured to receive the energy of the discharge of the inductor L1.

In some embodiments, the power conversion circuit 130 of the light emitting device driving device 100 further includes a first switching element W1 and a second switching element W2. The first switching element W1 is electrically connected to the inductor L1 and the energy storage element C1. The second switching element W2 is electrically connected to the inductor L1 and the power source 110. When the first switching element W1 is turned on, the energy storage element C1 is used to charge the inductor L1, where charging means that the second current I2 flowing through the inductor L1 is stepped up to store energy. When the second switching element W2 is turned on or the first switching element W1 is turned off, the inductor L1 is used to discharge to the power source 110. Compared to conventional power converters, the circuit architecture used in the present disclosure provides a current path for the power source 110 via the light emitting element 120 and the energy storage element C1, thereby improving conversion efficiency.

To facilitate the understanding of those skilled in the art, the operation of the light-emitting element driving device will be explained one by one as follows. Please refer to FIGS. 1 to 3 , wherein FIGS. 2A and 2B are schematic diagrams showing the power conversion circuit 130 in a first operating state and a second operating state, respectively. Fig. 3 is a waveform diagram of currents on the light-emitting element driving device 100.

First, as shown in FIG. 1, when the power source 110 starts discharging, the power source 110 supplies the first current I1 to the light emitting element 120, and the power source 110 also charges the energy storage element C1 through the light emitting element 120.

As the voltage stored by the energy storage element C1 rises, the first current I1 supplied to the light emitting element 120 gradually decreases (as shown in FIG. 3, the current fluctuation range of the first current I1 is extremely small, and the overall current is about 0.90 milliamperes to The power conversion circuit 130 will enter the first operational state when it is between 1.05 milliamperes, so it can be regarded as stable DC. As shown in FIG. 2A, in the first operational state, the power source 110 continues to provide the first current I1 to the light emitting element 120. At this time, the first switching element W1 will be turned on, so that the first switching element W1, the energy storage element C1 and the inductor L1 form a charging path P1, and the energy storage element C1 charges the inductor L1. As shown in FIGS. 2A and 3, when the power conversion circuit 130 is in the first operational state, a second current I2 is formed on the inductor L1, and in a charging phase T1, the second current I2 gradually rises. At the same time, a third current I3 also flows through the first switching element W1.

Referring to FIGS. 2B and 3, when the first switching element W1 is turned off, the power conversion circuit 130 will enter the second operational state. In the second operating state, the power source 110 still supplies the first current I1 to the light emitting element 120, and the electrical energy stored by the inductor L1 smoothly passes through the second switching element W2 to form a discharge path. In some embodiments, the first switch W1 is a controllable switch, and the second switching element W2 is a diode or a controllable switch. The controllable switch can be a metal-oxide-semiconductor field effect transistor (MOSFET), a gallium nitride (GaN) or a bipolar transistor (BJT), but not This is limited. If the second switch W2 is a diode, the positive terminal of the diode is electrically connected to the inductor L1. When the first switching element W1 is turned off, the electrical characteristic of the inductor L1 is to maintain the second current I2. Therefore, the second current I2 flows in the direction of the second switching element W2. At this time, the second switching element W2 is turned on, and the fourth current I4 flows through the second switching element W2. The second switching element W2 can also use a controllable switch, that is, a synchronous rectification well known to those skilled in the art, thereby further reducing the loss, which will not be described herein. The inductor L1, the second switching element W2, the power source 110, and the energy storage element C1 form a discharge path P2. The inductor L1 discharges (or recharges) its stored electrical energy to the power source 110 in a refill phase T2.

In some embodiments, the first switching element W1 switches between on or off according to a reference signal, so that the inductor L1 repeatedly performs charging and discharging processes (ie, the charging phase T1 and the recharging shown in FIG. 3). Stage T2), according to which, the voltage across the energy storage element C1 can be maintained at a predetermined value, so that the light-emitting element 120 operates at a constant current (as described above, the fluctuation range of the first current I1 is much smaller than the first current The amount of current of I1 can be regarded as constant current) and the consistency of luminous intensity is maintained.

In some embodiments, the power conversion circuit 130 can be operated in a Continuous Conduction Mode (CCM). When the power conversion circuit 130 is operated at the CCM, the average value of the current in the control power conversion circuit 130 (eg, the average of the second current I2) is equal to the average value of the first current I1.

For the foregoing purposes, the power conversion circuit 130 can use a corresponding control method. In some embodiments, when the power conversion circuit 130 is further controlled to the BCM and DCM Boundary Conduction Mode (BCM), the driving device 100 The electrical characteristics will conform to the identity: "I ₁ = (I _2-peak )/2", that is, the first current I1 on the light-emitting element 120 will be equal to the peak current in the power conversion circuit 130 (eg, flowing through the inductor) Half of the second current I2) of L1.

For example, if the input voltage provided by the power supply 110 is 48 volts, the inductance of the inductor L1 is 40 uH, the expected operating state of the illuminating element 120 is 36 volts and 1050 mA, the first switching element W1 operates at 100 kHz and the period is 78%. . At this time, the voltage across the energy storage element C1 should be 12 volts, and the peak current in the power conversion circuit 130 is 2100 milliamperes.

Through the characteristics when the power conversion circuit 130 is operated under the BCM (ie, the aforementioned identity), the driving device 100 can control the power conversion circuit 130 to enter the first operation state or the second operation by detecting the current value of the power conversion circuit 130. status. In some embodiments, the power conversion circuit 130 of the light emitting device driving device 100 further includes a control circuit 131. The control circuit 131 is configured to output a control signal to the first switching element W1 according to the reference signal to control the first switching element W1 to be turned on or off. The control circuit 131 is further configured to change a time point at which the first switching element W1 is turned on or off according to a detection current flowing through at least one of the first switching element W1, the second switching element W2, and the inductor L1.

For example, when the detection current reaches a predetermined current value (eg, 2100 milliamperes), the control circuit 131 turns off the first switching element W1 to cause the power conversion circuit 130 to enter the second operational state. In some embodiments, when the control circuit 131 controls the first switching element W1 to be turned on, the first switching element W1, the energy storage element C1 and the inductor L1 form a charging path P1. On the other hand, when the control circuit 131 controls the first switching element W1 to turn off, the turned-on second switching element W2, the inductor L1, and the power source 110 will form a discharge path P2.

Please refer to FIG. 4, which is another embodiment of the light-emitting element driving device 100 of the present disclosure. The light emitting device driving device 100 includes an energy storage device C1, a power source 110, and a power conversion circuit 130. The functions of the energy storage element C1, the inductor L1, the power source 110, the light emitting element 120, the power conversion circuit 130, the first switching element W1, the second switching element W2, and the control circuit 131 are similar to those of the embodiment shown in FIG. Therefore, it will not be repeated here. Compared with the embodiment shown in FIG. 1, the power conversion circuit 130 further includes at least one detecting component (such as R1, R2 or R3 shown in FIG. 4), and the detecting component is electrically connected to the first switching component W1 and the second At least one of the switching element W2 and the inductor L1 is configured to pass a detection current. The first switching element W1 is turned on in the first operating state or turned off in the second operating state depending on the magnitude of the detected current. In some embodiments, the detecting element includes a resistor or a current transformer, but is not limited thereto.

In some embodiments, as shown in FIG. 4, the power conversion circuit 130 includes a first detecting element R1, a second detecting element R2, and a third detecting element R3. The first detecting element R1 is connected in series with the inductor L1 for the second current I2 to flow. The second detecting element R2 is connected in series with the first switching element W1 for the third current I3 to flow. The third detecting element R3 is connected in series with the second switching element W2 for the fourth current I4 to flow.

As described above, if the overall operation of the power conversion circuit 130 belongs to the BCM, the first current I1 on the light-emitting element 120 will be equal to the peak current in the power conversion circuit 130 (eg, the second current I2 peak flowing through the inductor L1). Half of it. Therefore, in some embodiments, the power conversion circuit 130 detects a current flowing through at least one of the first switching element W1, the second switching element W2, and the inductor L1 (eg, the second current I2, the third current) I3 or the fourth current I4), and then controlling the first switching element W1 to be turned on or off according to the detection current. For example, if the first current I1 required for the light-emitting element 120 is 1050 milliamperes, the light-emitting element driving device 100 can double the first current I1 (ie, 2100 milliamps). ) is set to a preset current value. When the power conversion circuit 130 detects that the detection current reaches the preset current value, the control circuit 131 controls the first switching element W1 to be turned off to cause the power conversion circuit 130 to enter the second operational state.

One of the objects of the present disclosure is to stably maintain the first current I1 flowing through the light-emitting element 120. In other embodiments, if the illumination intensity of the light-emitting element 120 is to be adjusted, the first current I1 on the light-emitting element 120 can be changed correspondingly by changing the value of the preset current value. Referring to FIG. 3, when the preset current value is changed, the time when the power conversion circuit 130 enters the second operation mode will also change. For example, by increasing the preset peak current (eg, increasing to 2300 mAh), the time of the charging phase T1 will be extended, and the first current I1 on the illuminating element 120 is also increased (ie, 2300 mA). Half of the accompanying 1150 mAh), in this way, the light intensity emitted by the light-emitting element 120 can be accurately changed to realize the dimming function.

The present disclosure has been disclosed in the above embodiments, and is not intended to limit the disclosure, and the present disclosure may be variously modified and retouched without departing from the spirit and scope of the present disclosure. The scope of protection of the content is subject to the definition of the scope of the patent application.

100‧‧‧Lighting element drive

110‧‧‧Power supply

111‧‧‧AC voltage source

112‧‧‧Adjustment circuit

120‧‧‧Lighting elements

130‧‧‧Power conversion circuit

131‧‧‧Control circuit

C1‧‧‧ energy storage components

C2‧‧‧ input capacitor

L1‧‧‧Inductance

R1‧‧‧ first detection element

R2‧‧‧ second detection element

R3‧‧‧ third detection element

W1‧‧‧First switching element

W2‧‧‧Second switching element

P1‧‧‧Charging path

P2‧‧‧discharge path

I1‧‧‧First current

I2‧‧‧second current

I3‧‧‧ third current

I4‧‧‧ fourth current

T1‧‧‧Charging stage

T2‧‧‧Recharge stage

FIG. 1 is a schematic diagram of a light emitting device driving device according to some embodiments of the present disclosure. FIG. 2A is a schematic diagram showing a first operational state of the light-emitting element driving device according to some embodiments of the present disclosure. FIG. 2B is a schematic diagram showing a second operational state of the light-emitting element driving device according to some embodiments of the present disclosure. FIG. 3 is a current waveform diagram of a light-emitting element driving device according to some embodiments of the present disclosure. 4 is a schematic diagram of a light emitting device driving device according to some embodiments of the present disclosure.

Claims (18)

A light-emitting device driving device comprising: an energy storage component; a power source connected to a positive terminal of the energy storage component via the light-emitting component for supplying current to a light-emitting component and for charging the energy storage component; a power conversion circuit electrically connecting the power source and the energy storage component, wherein the power conversion circuit includes an inductor; wherein, in a first operating state of the power conversion circuit, the energy storage component charges the inductor In one of the second operating states of the power conversion circuit, the inductor is discharged to the power source. The light-emitting device driving device of claim 1, wherein the power conversion circuit further comprises: a first switching component electrically connected to the inductor and the energy storage component, and when the first switching component is turned on, the energy storage component is used To charge the inductor. The light-emitting device driving device of claim 2, wherein the power conversion circuit further comprises: a second switching component electrically connected to the inductor and the power source, wherein the inductor is used to discharge to the power source when the second switching component is turned on . The illuminating device driving device of claim 3, wherein the power conversion circuit further comprises: at least one detecting component electrically connected to at least one of the first switching component, the second switching component and the inductor for The detection current passes; wherein the first switching element is turned on in the first operating state or turned off in the second operating state according to the detecting current. The illuminating element driving device of claim 4, wherein the at least one detecting element comprises a resistor or a current comparator. The illuminating device driving device of claim 4, wherein the at least one detecting component comprises: a first detecting component connected in series with the inductor; a second detecting component connected in series with the first switching component; and a third detecting An element is connected in series with the second switching element. The illuminating device driving device of claim 1, wherein the power source comprises: an AC voltage source; an adjusting circuit electrically connected to the AC voltage source for receiving an AC voltage of the AC voltage source, and outputting an adjustment And an input capacitor electrically connected to the adjusting circuit for receiving the regulated voltage. The illuminating device driving device of claim 3, further comprising: a control circuit for controlling the first according to a detection current flowing through at least one of the first switching element, the second switching element and the inductor The switching element is turned on or off. The illuminating element driving device of claim 1, wherein the energy storage element comprises a capacitor. The illuminating device driving device of claim 3, wherein the second switching element comprises a diode. A method for driving a light-emitting component, comprising: supplying a current to a light-emitting component through a power source, and charging an energy storage component, wherein the power source is electrically connected to the first end of the light-emitting component, and the energy storage component is a positive terminal directly connected to the second end of the light emitting element; wherein the power source continuously supplies the current to the light emitting element, turning on a first switching element, causing the energy storage element to charge an inductor; and turning off the first A switching element discharges the inductor to the power source. The method of driving a light-emitting element according to claim 11, wherein after turning off the first switching element, the inductor is discharged to the power source through a second switching element. The method for driving a light-emitting element according to claim 12, further comprising: Detecting a detection current flowing through at least one of the first switching element, the second switching element, and the inductor; and controlling the first switching element to be turned on or off according to the detection current. The method for driving a light-emitting element according to claim 13, further comprising: controlling the first switching element to be turned off according to the detection current when the detection current reaches a predetermined current value. A light-emitting device driving device comprises: an energy storage component; a power source connected to a positive terminal of the energy storage component via a light-emitting component, wherein the power source supplies current to the light-emitting component, and is used for charging the energy storage component An inductor electrically connected to the energy storage component; a first switching component electrically connected to the energy storage component and the inductor, wherein the energy storage component is configured to charge the inductor when the first switching component is turned on; A second switching element electrically connects the inductor and the power source, wherein when the first switching element is turned off, the inductor is discharged to the power source through the second switching element. The illuminating element driving device of claim 15, wherein the energy storage element comprises a capacitor. The illuminating device driving device of claim 15, wherein the power source comprises an input capacitor for discharging the illuminating element and the energy storage element. The illuminating device driving device of claim 15, further comprising: at least one detecting component electrically connected to at least one of the first switching component, the second switching component and the inductor for passing a detection current; The first switching element is turned off according to the detection current.