TWI494024B - Illumination driving circuit - Google Patents

Description

Lighting drive circuit

The present disclosure relates to a lighting device, and more particularly to an illumination driving circuit on a lighting device.

In recent years, with the development of optoelectronic technology, many novel lighting devices have been developed in the industry. Among them, Light-Emitting Diode (LED) lamps have received extensive attention. The luminous efficiency and service life of the LED lamp are superior to those of the traditional incandescent lamp, and there is no environmental protection problem in manufacturing, which is in line with the trend of energy saving and environmental protection.

The most frequently mentioned advantages of lighting systems consisting of light-emitting diode lamps are high efficiency and long service life. In the high efficiency part, it can be divided into two characteristics: conversion efficiency and power factor (PF).

The conversion efficiency refers to the input of the AC input to the working output of the LED, and how much input power is actually transmitted to the LED during this process. The higher the ratio of input power to output power, the higher the conversion efficiency.

The power factor is related to the real power and virtual power of the power signal. The power company provides three-phase AC power with a mains voltage of 100V~110V or 200V~240V and a frequency of 50~60Hz. The instantaneous cancellation power of a typical resistive load is the product of voltage and current (P = VI). However, a purely inductive load or a purely capacitive load will cause a phase difference of 90° between current and voltage, resulting in real power loss. The instantaneous power dissipation is calculated as follows: P = VI cos θ , where I represents current , V represents the voltage, and θ is the phase difference angle between the current and the voltage.

In addition, the power factor is calculated as follows: Where PF represents the power factor, I represents the current, V represents the voltage, and θ is the phase difference angle between the current and the voltage.

As shown in the above equation, when there is a phase difference of 90° between the current and the voltage (for example, when the load is a purely inductive load or a purely capacitive load), the power factor will be drastically reduced to zero.

Since the light-emitting diode is not a purely resistive load, and the driving circuit for driving the light-emitting diode has the characteristics of inductance and capacitance, it will cause a phase difference between the input voltage and the input current and cause a power factor to decrease, which will make the power The company needs to output more power in order for the LED to reach the preset output power. The virtual power generated by the phase difference will be converted into unnecessary heat energy consumption. Therefore, the improvement of the power factor will effectively help the power company to reduce the output power and achieve substantial power savings.

Therefore, in order to achieve the trend of true energy saving, it is necessary to develop a light-emitting diode lighting device with a high power factor.

In today's LED lighting system, most of the drive circuit adopts a Buck structure, which is first rectified and supplied to the drive circuit. The illumination drive circuit of the general LED is divided into constant voltage and constant current. The constant voltage is relatively simple in design, but the output is easily affected by the use characteristics of the light-emitting diode (for example, the impedance of the light-emitting diode will gradually increase when used for a long time, resulting in a drop in operating current). The constant voltage operation is less stable than constant current. Accordingly, the present disclosure proposes a constant current drive architecture design.

In order to solve the above problems, the present disclosure proposes an illumination driving circuit which adopts a bootstrap type inductor current monitoring architecture, which can be realized by a high voltage side buck type architecture, and a sensing resistor element is added to the inductor in the illumination driving circuit of the present case. In front of the component, the node between the inductive component and the sensing resistor is used as the virtual ground of the control module, and the control module detects the node voltage between the sensing resistor component and the switching component to realize the inductor current. Monitoring to precisely control the inductor current flowing through the inductive component and subsequent illuminated loads.

One aspect of the present disclosure is to provide an illumination driving circuit for driving an illumination load. The illumination driving circuit includes a system voltage source, a switching element, an inductance element, an inductor current sensing module, and a control module. The switching element is coupled between the system voltage source and the illuminating load. An inductive component is connected in series between the switching component and the illumination load. The inductor current sensing module includes a sensing resistor element connected in series between the switching element and the inductive component. The control module is coupled to the control end of the switching element and is configured to control the conduction state of the switching element. The virtual ground end of the control module is coupled between the sensing resistance element and the inductance element, and the inductor current sensing end of the control module The control module is coupled between the sensing resistor element and the switching component, and the control module calculates the inductor current flowing through the inductor component by the voltage level of the inductor current sensing terminal.

In accordance with an embodiment of the present disclosure, a system voltage source includes an alternating voltage input and a rectifier circuit. The rectifier circuit is coupled between the AC voltage input and the switching element.

According to an embodiment of the present disclosure, the illumination driving circuit further includes an input voltage sensing module coupled to the input voltage sensing end of the control module, the input voltage sensing module includes a first voltage dividing resistor component, and a second Voltage divider resistor Components and capacitive components. The first voltage dividing resistor element is coupled between the system voltage source and the input voltage sensing terminal. The second voltage dividing resistor is coupled between the virtual ground and the input voltage sensing terminal. The capacitive element is coupled between the virtual ground and the input voltage sensing end.

According to an embodiment of the present disclosure, an input voltage sensing module is configured to sense an input voltage from an input voltage source of the system and transmit the input voltage to the control module, and the control module is configured to The phase of the inductor current is synchronized with the input voltage.

According to an embodiment of the present disclosure, an inductor current sequentially flows through the switching element, the sensing resistor element, the inductive element, and the illuminating load.

According to an embodiment of the present disclosure, the control module senses the inductor current according to a voltage difference between the inductor current sensing terminal and the virtual ground terminal and a resistance value of the sensing resistor element.

According to an embodiment of the present disclosure, the illumination driving circuit further includes a voltage starting module coupled to the activation sensing end of the control module, and the voltage starting module includes a resistive element, a diode, and a capacitive element. The resistor element is coupled between the system voltage source and the startup sensing terminal. The diode is coupled between the illuminating load and the startup sensing terminal. The capacitive element is coupled between the virtual ground and the activation sensing end.

According to an embodiment of the present disclosure, when the switching element is initially turned off, the input voltage of the system voltage source charges the capacitive element through the resistive element of the voltage starting module, so that the voltage level of the starting sensing terminal is increased. Until the voltage level of the startup sensing terminal satisfies a starting voltage threshold of the control module, then the control module turns on the closing component.

According to an embodiment of the present disclosure, the illumination driving circuit further includes a The output capacitor element is connected in parallel with the illuminating load. When the switching element is turned on, the input voltage of the system voltage source stores the inductor element and the output capacitor element through the switching element until the voltage of the inductor current sensing terminal The level reaches a locking voltage threshold of one of the control modules, and then the control module turns off the closing element.

According to an embodiment of the present disclosure, after the control module turns off the off component, the inductive component releases the illuminating load and generates the inductor current, and the control module is configured by the voltage level of the inductor current sensing terminal. The inductor current is monitored, and the control module re-energizes the off component when the inductor current is below an inductor current threshold.

FIG. 1 is a schematic diagram showing the operation of an illumination driving circuit 100 according to an embodiment of the present invention. The illumination driving circuit 100 is used to drive the illumination load 110. In this embodiment, the illumination load 110 may be a light-emitting diode. Polar body load, or other equivalent non-pure resistive illuminating load.

The illumination driving circuit 100 includes a system voltage source 120, a switching element Q1, an inductance element L1, an inductor current sensing module 140, and a control module 160.

The input end and the output end of the switching element Q1 are coupled between the system voltage source 120 and the illuminating load 110. In this embodiment, the switching element Q1 can be a semiconductor switch. The control module 160 is coupled to the control terminal of the switching element Q1 (such as the gate of the semiconductor switch) and is used to control the conduction state of the switching element Q1.

The inductance element L1 is connected in series between the switching element Q1 and the light-emitting load 110.

In this embodiment, the illumination driving circuit 100 includes an inductor current sensing module 140 for directly or indirectly sensing the inductor current I _L flowing through the inductive component L1. As shown in FIG. 1, the inductor current sensing module 140 includes a sensing resistor element R _S connected in series between the switching element Q1 and the inductive element L1.

The inductor current sensing terminal CS of the control module 160 is coupled to the first node N1 between the sensing resistor element R _S and the switching element Q1. The virtual ground GND of the control module 160 is coupled to the second node N2 between the sensing resistive element R _S and the inductive component L1. The above connection method is the bootstrap type inductor current monitoring architecture proposed in the present disclosure.

The control module can know the voltage difference between the voltage level of the inductor current sensing terminal CS (ie, the voltage of the first node N1) and the voltage level of the virtual ground GND (ie, the voltage of the second node N2). Since the sense resistor element R _S has a known fixed resistance value in the design, the control module can calculate the inductor current I _L flowing through the inductor element L1 from the voltage difference between N1 and N2.

In this example, the control module 160 uses the voltage level of the second node N2 between the sensing resistance element R _S and the inductance element L1 as the ground potential used by the control module 160. That is to say, the control module 160 can know the inductor current I _L flowing through the inductor element L1 by detecting the voltage level of the inductor current sensing terminal CS. It should be added that, in this example, the inductor current I _L sequentially flows through the switching element Q1, the sensing resistance element R _S , the inductance element L1 , and the illuminating load 110 . Therefore, the control module 160 can substantially sense the operating current flowing through the lighting load 110 from the inductor current I _L . In practical applications, the illumination driving circuit 100 may further include other components.

Please refer to Figure 2 and Figure 3 together. Figure 2 is based on the drawing. A functional block diagram of an illumination driving circuit 100 according to an embodiment of the present invention, and FIG. 3 is a circuit diagram of the illumination driving circuit 100 according to the embodiment of FIG. 2. FIG. 3 is one of the circuit implementation architectures of illumination driver circuit 100, but the disclosure is not limited to such circuit implementations.

In the embodiment shown in FIG. 2 , the illumination driving circuit 100 further includes an input voltage sensing module 180 and a voltage starting module 190 . The input voltage sensing module 180 and the voltage starting module 190 are electrically connected to the input node between the system voltage source 120 and the switching element Q1, respectively, for sensing the input signal generated by the system voltage source 120. As shown in FIG. 3, the illumination driving circuit 100 further includes an output capacitive element C _OUT connected in parallel with the illuminating load 110.

As shown in FIG. 3, system voltage source 120 can include an alternating voltage input VAC and a rectifier circuit (bridge rectifier BD in this embodiment). The bridge rectifier BD is coupled between the AC voltage input VAC and the switching element Q1. In some embodiments, the AC voltage input VAC can be an external mains outlet.

The input voltage sensing module 180 is coupled to the input voltage sensing terminal VS of the control module 160. As shown in FIG. 3, the input voltage sensing module 180 includes a first voltage dividing resistor element R _P1 , a second voltage dividing resistor element R _{P2 ,} and a capacitor element C _P1 . The first voltage dividing resistor element R _{P1 is} coupled between the system voltage source 120 and the input voltage sensing terminal VS. The second voltage dividing resistor R _{P2 is} coupled between the virtual ground GND and the input voltage sensing terminal VS. The capacitive component C _{P1 is} coupled between the virtual ground GND and the input voltage sensing terminal VS.

The input voltage sensing module 180 is configured to sense an input voltage from the system voltage source 120 and transmit it to the input voltage sensing terminal VS of the control module 160. The control module 160 learns from the system according to the voltage level of the input voltage sensing terminal VS (representing the input voltage of the system voltage source 120) and the voltage level of the inductor current sensing terminal CS (representing the input current of the system voltage source 120). The relationship between the input voltage and current of voltage source 120. The control module 160 can adjust the conduction state (such as the on frequency, the bandwidth, the phase, and the like) of the switching element Q1 according to the relationship described above to synchronize the phase of the inductor current I _L with the input voltage.

Please refer to FIG. 4, which is a timing diagram of the signal of the illumination driving circuit 100 in an embodiment. As shown in FIG. 4, the upper waveform is the voltage level on the input voltage sensing terminal VS (ie, the input voltage of the system voltage source 120 after passing through the bridge rectifier BD). The control module 160 adjusts the conduction state of the switching element Q1 to synchronize the phase of the inductor current I _L with the input voltage (see the VS waveform in FIG. 4).

In addition, as shown in FIG. 3, the voltage starting module 190 of the illumination driving circuit 100 is coupled to the activation sensing terminal VIN of the control module 160, and the voltage starting module 190 includes a resistive element R _IN , a diode D _{2 ,} and Capacitor element C _IN . The resistive element R _{IN is} coupled between the system voltage source 120 and the startup sense terminal VIN. The diode D _{2 is} coupled between the light-emitting load 110 and the start sensing terminal VIN. The capacitive element C _{IN is} coupled between the virtual ground GND and the start sensing terminal VIN. The voltage starting module 190 is used to drive the control module 160 into a normal working state during initial startup.

The following paragraphs briefly describe the manner of operation of the illumination driving circuit 100 in the present disclosure with an operational embodiment, but the invention is not limited thereto. In an initial state (e.g., when the lighting load 110 has not been illuminated), the switching element Q1 is initially turned off. System voltage source 120 is activated and begins to provide an input voltage. The input voltage of the system voltage source 120 charges the capacitive element C _IN via the resistive element R _IN of the voltage starting module 190, so that the voltage level of the sense sensing terminal VIN is increased until the voltage level of the sensing terminal VIN is met to satisfy the control mode. The starting voltage threshold for group 160. When the voltage level of the sense terminal VIN is met to satisfy the threshold voltage of the control module 160, the control module 160 turns on the off component Q1. Thereby, the initial startup of the illumination driving circuit 100 is completed.

After the switching element Q1 is turned on, the input voltage of the system voltage source 120 stores the inductor element L1 and the output capacitor element C _OUT via the switching element Q1, so that the voltage level of the inductor current sensing terminal CS gradually rises until the inductor current The voltage level of the influenza terminal CS reaches the threshold voltage threshold of the control module 160. When the voltage level of the inductor current sensing terminal CS reaches the locking voltage threshold of the control module 160, the control module 160 turns off the closing component Q1.

After the control module 160 turns off the closing component Q1, the inductor component L1 releases the light-emitting load 110 and generates an inductor current I _L , and the control module 160 is connected to the voltage level of the inductor current sensing terminal CS (ie, the sensing resistor component R). The first node N1 potential between _S and switching element Q1) monitors the inductor current I _L . At the same time, the input voltage sensing module 180 can further provide the obtained voltage level (representing the input voltage) to the input voltage sensing terminal VS of the control module 160, and the control module 160 pairs the inductor current I _L and The input voltage is phase synchronized (as shown in Figure 4).

When the inductor current I _{L is} lower than the inductor current threshold (for example, when the voltage level of the inductor current sensing terminal CS is lower than a threshold voltage value), the control module 160 re-turns the off component Q1, thereby circulating operation to provide The drive signal is stabilized to the illuminating load 110, wherein the average current flowing through the illuminating load 110 approaches a sinusoidal waveform of a positive level (such as the average current Iavg in FIG. 4).

In summary, the present disclosure proposes an illumination driving circuit that adopts a bootstrap type inductor current monitoring architecture, which can be realized by a high voltage side buck architecture, and a sensing resistor component is added to the inductor in the illumination driving circuit of the present invention. In front of the component, the node between the inductive component and the sensing resistor is used as the virtual ground of the control module, and the control module detects the node voltage between the sensing resistor component and the switching component to realize the inductor current. Monitoring to precisely control the inductor current flowing through the inductive component and subsequent illuminated loads.

The present disclosure has been disclosed in the above embodiments, but it is not intended to limit the disclosure, and any person skilled in the art can make various changes and refinements without departing from the spirit and scope of the disclosure. The scope of protection of the disclosure is subject to the definition of the scope of the patent application.

100‧‧‧Lighting drive circuit

110‧‧‧Lighting load

120‧‧‧System voltage source

140‧‧‧Inductance Current Sensing Module

160‧‧‧Control Module

180‧‧‧Input voltage sensing module

190‧‧‧Voltage Starter Module

Q1‧‧‧Switching elements

L1‧‧‧Inductance components

R _S ‧‧‧Sensor resistance element

The above and other objects, features, advantages and embodiments of the present disclosure will become more apparent and understood. The description of the drawings is as follows: FIG. 1 illustrates an operation of an illumination driving circuit according to an embodiment of the present invention. 2 is a functional block diagram showing an illumination driving circuit according to an embodiment of the present invention; FIG. 3 is a circuit diagram of a lighting driving circuit according to an embodiment of FIG. 2; and FIG. Illustrating an illumination driving circuit according to an embodiment of the present invention Signal timing diagram.

100‧‧‧Lighting drive circuit

110‧‧‧Lighting load

120‧‧‧System voltage source

140‧‧‧Inductance Current Sensing Module

160‧‧‧Control Module

180‧‧‧Input voltage sensing module

190‧‧‧Voltage Starter Module

Q1‧‧‧Switching elements

L1‧‧‧Inductance components

Claims (10)

An illumination driving circuit for driving an illumination load, the illumination driving circuit comprising: a system voltage source; a switching element coupled between the system voltage source and the illumination load; and an inductive component serially connected to the switch Between the component and the illuminating load; an inductor current sensing module comprising a sensing resistor element connected in series between the switching component and the inductive component; and a control module coupled to the one of the switching component And the one end of the control module is coupled to the sensing resistor element and the inductive component, and the inductor current sensing end of the control module is coupled to the Between the sensing resistor element and the switching component, the control module calculates an inductor current flowing through the inductor component from a voltage level of the inductor current sensing terminal, wherein the input voltage sensing terminal of the control module receives An input voltage from one of the system voltage sources, the control module synchronizing the phase of the inductor current with the phase of the input voltage according to the input voltage. The illumination driving circuit of claim 1, wherein the system voltage source comprises: an alternating voltage input; and a rectifying circuit coupled between the alternating voltage input and the switching element. The illumination driving circuit of claim 1, wherein the illumination driving circuit further comprises an input voltage sensing module coupled to the input voltage sensing end of the control module, the input voltage sensing module comprising: a first voltage-dividing resistor is coupled between the voltage source of the system and the input voltage sensing terminal; a second voltage-dividing resistor is coupled between the virtual ground and the input voltage sensing terminal; And a capacitive component coupled between the virtual ground and the input voltage sensing terminal. The illumination driving circuit of claim 3, wherein the input voltage sensing module is configured to sense the input voltage from the voltage source of the system and transmit the input voltage to the input voltage sensing end of the control module, the control mode The group adjusts the conduction state of the switching element according to the voltage level on the sensing terminal of the input voltage and the voltage level of the sensing current sensing terminal, so that the phase of the inductor current is synchronized with the phase of the input voltage, wherein the conducting state Includes the turn-on frequency. The illumination driving circuit of claim 1, wherein the inductor current sequentially flows through the switching element, the sensing resistor element, the inductive element, and the illuminating load. The illumination driving circuit of claim 5, wherein the control module senses the inductor current according to a voltage difference between the inductor current sensing terminal and the virtual ground terminal and a resistance value of the sensing resistor component . The lighting driving circuit of claim 1, wherein the lighting driving circuit further comprises a voltage starting module coupled to one of the control module to activate the sensing end, the voltage starting module comprising: a resistive component, coupled Connected between the voltage source of the system and the startup sensing terminal; a diode coupled between the illumination load and the startup sensing terminal; and a capacitive component coupled to the virtual ground and the startup Between the sensing ends. The illumination driving circuit of claim 7, wherein when the switching element is initially turned off, the input voltage of the system voltage source charges the capacitive element via the resistive element of the voltage starting module, so that the starting sensing end The voltage level is increased until the voltage level of the start sensing terminal satisfies a starting voltage threshold of the control module, and then the control module turns on the closing element. The illumination driving circuit of claim 8, wherein the illumination driving circuit further comprises an output capacitive component connected in parallel with the illuminating load, wherein when the switching component is turned on, an input voltage of the system voltage source is connected to the inductor via the switching component The component and the output capacitive component are stored until the voltage level of the inductor current sensing terminal reaches a locking voltage threshold of the control module, and then the control module turns off the closing component. The illumination driving circuit of claim 9, wherein the control mode After the group closes the off component, the inductive component releases the illuminating load and generates the inductor current, and the control module monitors the inductor current by the voltage level of the inductor current sensing terminal, when the inductor current is lower than one The control module re-energizes the shut-off element when the inductor current threshold is reached.