KR20110121592A - Method and device for obtaining conduction angle, method and device for driving led - Google Patents

Abstract

PURPOSE: A method and device for obtaining a conduction angle of a trailing edge dimmer, and a method and device for driving an LED are provided to remove the flicker of an LED due to the jittering of a dimmer. CONSTITUTION: A conduction point of a trailing edge dimmer is determined(S310). A fastest point is determined when the deviation is shown from an ideal waveform(S320). A conduction angle of the trailing edge dimmer is determined by using the conduction point of the trailing edge dimmer and the fastest point(S330).

Description

METHOD AND DEVICE FOR OBTAINING CONDUCTION ANGLE, METHOD AND DEVICE FOR DRIVING LED}

The present invention relates to a method and device for obtaining a conduction angle of a trailing edge dimmer. In addition, the present invention relates to a method and a device for driving an LED.

Currently, dimmers widely used in the market are designed for purely resistive loads such as incandescent lamps. These dimmers adjust the effective value of the input voltage via phase control to achieve brightness control for the lamp. The phase controlled dimmer mainly includes a leading edge dimmer and a trailing edge dimmer. 1 shows the general connection method of the dimmer of the prior art and the ideal output waveform of the dimmer, respectively.

The LED device cannot be connected directly to the mains supply network like an incandescent lamp and therefore conventional dimmers cannot be used directly for dimming. Instead, the switching power supply needs to be used as a DC drive device for the LED device. Therefore, it is desirable for such LED drive devices to be compatible with conventional dimmers. However, there is no satisfactory device provided in the prior art that is compatible with the conventional dimmer, and in particular, no satisfactory device that is compatible with the trailing edge dimmer is provided.

It is an object of the present invention to provide a method and device for obtaining the conduction angle of a trailing edge dimmer. It is another object of the present invention to provide a method and device for driving an LED that is compatible with a leading edge dimmer and a trailing edge dimmer simultaneously.

According to an embodiment of the present invention, a method for obtaining a conduction angle of a trailing edge dimmer is provided, the method comprising: determining a time point t0 when the trailing edge dimmer begins to conduct; Determining the earliest time point t1 when the deviation from the ideal waveform appears; And determining the conduction angle t1-t0 of the trailing edge dimmer based on the earliest time t1 when the deviation from the ideal waveform appears and the time t0 when the trailing edge dimmer starts to conduct. It includes.

In this method, the conduction angle of the trailing edge dimmer can be effectively determined, so that the LED can be dimmed according to the conduction angle of the trailing edge dimmer, and the influence of any interference can be reduced.

In addition, in accordance with an embodiment of the present invention, a method of driving an LED is provided, the method comprising: determining a type of dimmer; When it is determined that the connected dimmer is a leading edge dimmer, obtaining a conduction angle of the leading edge dimmer; When it is determined that the connected dimmer is a trailing edge dimmer, obtaining the conduction angle of the trailing edge dimmer in the above method; And generating a dimming signal in accordance with the obtained conduction angle of the dimmer.

In this way, compatibility with the leading edge dimmer and trailing edge dimmer can be effectively achieved, and the LED can be dimmed according to the conduction angle of the phase dimmer. In addition, any interference can be reduced, and flickering of the LED caused by jittering of the dimmer can be eliminated.

Furthermore, according to an embodiment of the present invention, there is provided a conduction angle obtaining device for a trailing edge dimmer, the conduction angle obtaining device comprising: a conduction configured to determine a time point t0 when the trailing edge dimmer begins to conduct. A viewpoint determination unit; A phase cutting point determining unit configured to determine the earliest time point t1 when the deviation from the ideal waveform appears; And a conduction angle t1-t0 of the trailing dimmer based on the earliest time t1 when the deviation from the ideal waveform appears and a time to when the trailing edge dimmer begins to conduct. Each decision unit is included.

In this device, the conduction angle of the trailing edge dimmer can be effectively determined to perform dimming on the LED according to the conduction angle of the trailing edge dimmer. In addition, the effects of any interference can be reduced.

In addition, according to an embodiment of the present invention, an LED driving device is provided, the LED driving device comprising: a dimmer type determining unit configured to determine a type of dimmer; A conduction angle obtaining device for the leading edge dimmer, configured to obtain a conduction angle of the leading edge dimmer when the connected dimmer is determined to be a leading edge dimmer; A conduction angle obtaining device for the trailing edge dimmer as described above, configured to obtain a conduction angle of the trailing edge dimmer when it is determined that the connected dimmer is a trailing edge dimmer; And a dimming unit configured to generate a dimming signal in accordance with the obtained conduction angle of the dimmer.

In the LED drive device, compatibility with the leading edge dimmer and trailing edge dimmer can be effectively achieved, and the LED can be dimmed according to the conduction angle of the phase dimmer. In addition, the influence of any interference can be reduced, and the flickering of the LED caused by jitter of the dimmer can be eliminated.

Furthermore, according to an embodiment of the present invention, an LED driving method is provided, the LED driving method comprising: generating a PWM control signal with a PWM dimming signal; And controlling the PWM DC / DC converter with a PWM control signal to generate a drive voltage for the LED.

In this way, PWM dimming can be used, while effective isolation between the LED device and the high voltage power supply can be ensured.

Furthermore, according to an embodiment of the present invention, an LED drive system is provided, the LED drive system comprising: a PWM DC / DC converter, a PWM controller and a PWM dimming signal generating unit; Wherein the PWM dimming signal generating unit is configured to generate a PWM dimming signal; The PWM controller is configured to generate a PWM control signal by using a PWM dimming signal; The PWM DC / DC converter is configured to generate the driving voltage of the LED according to the PWM control signal.

In such LED drive systems, PWM dimming can be used, while effective isolation between the LED device and the high voltage power supply can be ensured, thus ensuring that the system can be easily designed according to safety standards. In addition, since the system has a simple structure, the production cost is greatly reduced, and accurate constant current characteristics can be ensured. Thus, highly accurate requirements regarding LED current can be met.

The invention may be better understood in conjunction with the following figures in conjunction with the drawings, in which like or similar reference numerals are used to indicate the same or similar components. All drawings and detailed description are included in and constitute a part of the specification, and are used to illustrate preferred embodiments of the present invention and to further provide examples for explaining the principles and advantages of the present invention.

1 shows a general connection method of a dimmer of the prior art and an ideal output waveform of the dimmer.
2 shows an exemplary waveform of the rectified output voltage of the trailing edge dimmer.
3 shows a flowchart of a method for obtaining a conduction angle of a trailing edge dimmer according to an embodiment of the present invention.
4 shows an exemplary waveform of the rectified output voltage of the leading edge dimmer.
5 shows a flowchart of a method for driving an LED that is compatible with a leading edge dimmer and a trailing edge dimmer.
6 shows a principle diagram for the detection of a dimmer.
7 shows a schematic block diagram of a conduction angle acquisition device for a trailing edge dimmer according to an embodiment of the invention.
8 shows a block diagram of an LED drive device compatible with a leading edge dimmer and trailing edge dimmer in accordance with an embodiment of the present invention.
9 schematically illustrates the principle of linear dimming.
10 schematically illustrates the principle of PWM dimming.
11 shows a flowchart of a method for driving an LED in accordance with an embodiment of the invention.
12 schematically shows the waveform of the generated PWM control signal.
13 shows a schematic structural diagram of an LED driving system according to an embodiment of the present invention.

In the drawings, the same reference numerals are used for the same or corresponding components.

Hereinafter, embodiments of the present invention will be described in cooperation with the drawings. In view of clarity and simplicity, not all features of actual embodiments are described in the detailed description. However, it is to be understood that many of the decisions specific to the embodiments need to be made during the development of any practical embodiments to achieve the developer's specific goals, and that these decisions may vary to some extent in accordance with different embodiments. It must be understood. In addition, although development work may be rather complex and time-consuming, it should be understood that it is only a routine job to those skilled in the art that would benefit from the specification of the present invention.

In the drawings, only device structures which are closely related to the solution of the present invention are shown in the drawings, and other details which are of little relevance to the present invention are omitted to avoid obscuring the present invention due to unnecessary details. It should be further pointed out here.

First Example

We recognize that for trailing edge dimmers, capacitors with typical values of 100nF-150nF are generally connected in parallel with the output terminals of the trailing edge dimmer. In addition, an electro-magnetic interference (EMI) filter on the input terminal of the LED driver generally also includes a capacitor. These capacitors can cause the output voltage of the dimmer to not decrease as quickly as in an ideal waveform. 2 shows an exemplary waveform of the rectified output voltage of the trailing edge dimmer. As shown in FIG. 2, before the start of another cycle, the voltage is reduced to zero after a relatively long time period. In such a situation, the time point t2 when the output voltage of the dimmer is reduced to zero cannot correctly reflect the conduction angle of the dimmer, which may cause the LED lamp to not be dimmed correctly or the dimmable range becomes considerably narrower. Can be. This is because there is no dimmable LED lamp on the market that is actually compatible with the trailing edge dimmer.

The inventors have recognized that, after the phase cutting of the trailing edge dimmer, as shown in FIG. 2, there is a certain difference between the waveform of the voltage and the ideal waveform, although the voltage cannot be reduced rapidly to zero. Therefore, if the earliest point in time t1 at which the deviation from the ideal waveform appears can be determined, it may be considered that the trailing edge dimmer performs phase cutting at this point. Thus, it can be determined that the conduction angle of the trailing edge dimmer is t1-t0, where t0 is the point in time when the trailing edge dimmer starts to conduct.

Based on the above considerations, according to an embodiment of the present invention, a method for obtaining a conduction angle of a trailing edge dimmer is provided. 3 shows a flow chart of this method. As shown in FIG. 3, the method includes the following steps:

S310: Determine a time point t0 when the trailing edge dimmer starts to conduct. After time t0, the trailing edge dimmer begins to conduct, so the output voltage of the dimmer should be substantially equal to the ideal waveform. The ideal waveform is assumed to be a sinus wave in FIG. Thus, in the conduction phase of the trailing edge dimmer starting at time t0, the output voltage is substantially equal to a sine wave.

S320: Determine the earliest time point t1 when the deviation from the ideal waveform appears. In particular, in step S320, sampling can be performed on the output voltage of the trailing edge dimmer, the sampled values are compared to the ideal waveform, and the earliest time point t1 when the deviation from the ideal waveform appears. Determined based on the difference between the output voltage and the ideal waveform. When time point t1 is determined, time point t1 is considered to be the phase cutting point of the trailing edge dimmer.

S330: determining the conduction angle t1-t10 of the trailing edge dimmer based on the earliest time t1 when the ideal waveform appears and the time t0 when the trailing edge dimmer starts to conduct.

When the conduction angle of the trailing edge dimmer is obtained, the LED may be dimmed according to the determined conduction angle. For example, a PWM (pulse width modulation) signal can be generated according to the conduction angle of the dimmer, the duty cycle of the PWM signal is related to the conduction angle of the dimmer, and the PWM signal is used for adjustment of the LED brightness. It is also possible for sure that linear dimming is performed according to the conduction angle of the dimmer which can be easily understood by one skilled in the art.

Since the LED drive device is not a resistive load, there may be a situation where the matching between the LED drive device and the dimmer is not particularly ideal. In this situation, the output of the LED driving device can have any interference, so flickering of the LED lamp can easily be caused. For this situation, to reduce the effect of any interference, it is necessary to calculate the average value of the conduction angles obtained in multiple cycles during the process of detecting the conduction angle of the dimmer and to perform dimming on the LEDs according to the average value. desirable.

In the method for obtaining the conduction angle of the trailing edge dimmer according to the present embodiment, the conduction angle of the trailing edge dimmer can be effectively determined to perform dimming on the LED according to the conduction angle of the trailing edge dimmer. In addition, the effects of any interference can be reduced.

2nd Example

Conventional dimmers include leading edge dimmers and trailing edge dimmers. Therefore, according to an embodiment of the present invention, a method is provided for driving an LED that is compatible with a leading edge dimmer and a trailing edge dimmer.

Before showing the method for driving the LED in detail, the method for obtaining the conduction angle of the leading edge dimmer is described first. 4 shows an exemplary waveform of the rectified output voltage of the leading edge dimmer. As can be seen from the figure, in the period between the time point t0 and the time point t1, the output voltage of the leading edge dimmer is substantially zero. At time t1, the leading edge dimmer is conductive, so that a jump appears at the output voltage. By the time point t2, the output voltage decreases to zero according to the standard voltage. Thus, in order to detect the conduction angle of the leading edge dimmer, only detecting the zero crossing voltage at the time points t1 and t2 is required. This method for obtaining the conduction angle of the leading edge dimmer is familiar to those skilled in the art and will not be shown in detail here.

5 shows a flowchart of a method for driving an LED that is compatible with the leading edge dimmer and trailing edge dimmer. As shown in FIG. 5, the method includes the following steps:

S510: Detecting whether a dimmer is connected. 6 may be referred to, wherein a principle diagram for dimmer detection is schematically shown. In operation, the LED drive device 620 performs sampling and analysis on the voltage at point A at a specific sampling rate via a resistor voltage divider. In step S510, the LED driving device 620 compares the sampled voltage with a reference voltage. The reference voltage may already be stored in the LED driving device 620 or input from the outside. The LED drive device 620 can analyze the times when the sampled voltage is above and below the reference voltage, and takes such time information as a reference to determine if the dimmer is connected. It will be readily appreciated by those skilled in the art that the LED driving device may be implemented with a micro-controller such as an MCU or a DSP.

In the method according to the invention, it should be noted that step S510 is optional. For example, depending on the configuration, it may be considered the default that the dimmer is connected so that later steps can be implemented directly.

S520: Determine the type of the dimmer when it is determined that the dimmer is connected. It can be seen from FIG. 1 that the output waveform of the leading edge dimmer is clearly different from the output waveform of the trailing edge dimmer. Thus, the type of dimmer may be determined according to the sampled signals.

When it is determined that the connected dimmer is a leading edge dimmer, the conduction angle of the leading edge dimmer is obtained by the method for obtaining the conduction angle of the leading edge dimmer as described above.

When it is determined that the connected dimmer is a trailing edge dimmer, the conduction angle of the trailing edge dimmer is obtained by the method for obtaining the conduction angle of the trailing edge dimmer as described in the first embodiment of the present invention.

Subsequently, in step S550, the dimming signal is generated according to the obtained conduction angle.

Similar to the first embodiment, in order to reduce any interference influence, calculate the average value of the conduction angles obtained in a plurality of cycles during the process of detecting the conduction angle of the dimmer, and then adjust the dimming for the LED according to the average value. It is preferable to carry out.

In operation of the dimmer, jitter can occur due to jitter in the input signal, etc., and corresponding small changes can be caused in the dimmer angle of the dimmer. In practice, however, it is not desired to change the dimming of the LED at this time. Thus, in the method according to the embodiment, it is preferable that the anti-jittering control step is configured after the conduction angle of the dimmer is obtained. In the anti-jittering control step, a change in the conduction angle of the dimmer is detected, and only when the change in the conduction angle of the dimmer is greater than a certain threshold, a dimming signal is generated in the dimming step according to the changed conduction angle of the dimmer. Thus, flickering of the LED caused by jitter of the dimmer can be eliminated.

In the method for driving the LED according to the present embodiment, compatibility with the leading edge dimmer and trailing edge dimmer can be effectively achieved, and the LED can be dimmed according to the conduction angle of the phase dimmer. In addition, the influence of any interference can be reduced, and the flickering of the LED caused by jitter of the dimmer can be eliminated.

3rd Example

 The third embodiment of the present invention corresponds to the first embodiment above, where a conduction angle obtaining device for the trailing edge dimmer 700 is described. 7 shows a schematic block diagram of a conduction angle acquisition device for a trailing edge dimmer 700 according to a third embodiment of the invention. As shown in FIG. 7, the conduction angle acquisition device for the trailing edge dimmer 700 includes:

A conduction time determination unit 710, configured to determine a time point t0 when the trailing edge dimmer starts to conduct. After the time point t0, the trailing edge dimmer starts to conduct, so the output voltage must be substantially equal to the anomaly waveform. The ideal waveform is assumed to be the sine wave of FIG. Thus, in the conduction phase of the trailing edge dimmer starting from time point t0, the output voltage is substantially equal to a sine wave.

Phase cutting point determination unit 720, configured to determine the earliest time point t1 when the deviation from the ideal waveform appears. In particular, the phase cutting point determination unit 720 can further include a sampling device and a comparison device, where the sampling device is configured to perform sampling on the output voltage of the trailing edge dimmer to obtain sampled values, and The comparison device is configured to compare the sampled values with the ideal waveform and determine the earliest time point t1 when a deviation from the ideal waveform appears based on the difference between the output voltage and the ideal waveform. When time point t1 is determined, time point t1 is considered to be the phase cutting point of the trailing edge dimmer.

The conduction configured to determine the conduction angle (t1-t0) of the trailing edge dimmer based on the earliest time point t1 when the deviation from the ideal waveform appears and the time point t0 when the trailing edge dimmer begins to conduct. Each decision unit 730.

Since the LED drive device is not a resistive load, there may be a situation where the matching between the LED drive device and the dimmer is not particularly ideal. In this situation, the output of the LED driving device can have any interference, so flickering of the LED lamp can easily be caused. For this situation, in order to reduce the influence of any interference, the conduction angle determination unit 730 calculates an average value of the conduction angles obtained in a plurality of cycles during the process of detecting the conduction angle of the dimmer, and finally obtained It is desirable to further include an averaging device configured to take an average value as the conduction angle.

In the conduction angle obtaining device for the trailing edge dimmer 700 according to the present embodiment, the conduction angle of the trailing edge dimmer can be effectively determined to perform dimming on the LED according to the conduction angle of the trailing edge dimmer. In addition, the effects of any interference can be reduced.

Fourth Example

A fourth embodiment of the present invention corresponds to the second embodiment, wherein an LED drive device 800 is described that is compatible with the leading edge dimmer and trailing edge dimmer.

8 shows a block diagram of an LED drive device compatible with a leading edge dimmer and a trailing edge dimmer in accordance with an embodiment of the present invention. As shown in FIG. 8, the LED drive device 800 includes the following modules:

Dimmer detection unit 810, configured to detect whether a dimmer is connected. 6 may be referred to, wherein a principle diagram for dimmer detection is schematically shown. See the description of the second embodiment for a detailed procedure for dimmer detection, which will not be described again here. As described in the second embodiment, the dimmer detection unit 810 is optional in the LED drive device 800.

A dimmer type determination unit 820 configured to determine the type of the dimmer when it is determined that the dimmer is connected. It can be seen from FIG. 1 that the output waveform of the leading edge dimmer is clearly different from the output waveform of the trailing edge dimmer. Thus, the dimmer type determination unit 820 may determine the type of the dimmer according to the sampled signals.

A conduction angle obtaining device for the leading edge dimmer 830, configured to obtain the conduction angle of the leading edge dimmer in a method for detecting the conduction angle of the leading edge dimmer when the connected dimmer is determined to be the leading edge dimmer.

A conduction angle obtaining device for a trailing edge dimmer 700 as described in the third embodiment of the present invention, configured to obtain the conduction angle of the trailing edge dimmer when it is determined that the connected dimmer is a trailing edge dimmer.

A dimming unit 850 configured to generate a dimming signal in accordance with the obtained conduction angle.

Preferably, the conduction angle acquisition device for the leading edge dimmer 830 and the conduction angle acquisition device for the trailing edge dimmer 700 are configured to calculate an average value of the conduction angles obtained in multiple cycles, so that any interference In order to reduce the influence of the dimming unit 850 may perform dimming on the LED according to the average value.

In addition, the LED driving device 800 includes an anti-jittering control unit (not shown) configured to detect a change in the conduction angle of the dimmer, and only when the change in the conduction angle of the dimmer is greater than a certain threshold. It is also desirable for the signal to be generated in accordance with the changed conduction angle of the dimmer. Thus, flickering of the LED caused by jitter of the dimmer can be eliminated.

In the LED drive device 800 according to the present embodiment, compatibility with the leading edge dimmer and trailing edge dimmer can be effectively achieved, and the LED can be dimmed according to the conduction angle of the phase dimmer. In addition, the influence of any interference can be reduced, and the flickering of the LED caused by jitter of the dimmer can be eliminated.

5th Example

The inventors recognize that a high voltage mains supply in the range of 100V to 230V is generally used as the input power source of the LED device. In order to meet safety requirements, it is desirable to insulate the LED device from such a high voltage power supply to avoid potential damage to humans. On the other hand, it is known to those skilled in the art that there are two methods for dimming an LED, namely linear dimming and PWM dimming. 9 schematically illustrates the principle of linear dimming. As can be seen from Fig. 9, the magnitude of the current flowing through the LED varies depending on the dimming signal. Since LEDs achieve the highest luminous efficiency and achieve nominal color temperature (key parameters of the LED) only in the case of rated operating currents, linear dimming reduces the luminous efficiency of the LEDs and changes in drive current. Accordingly changes the color temperature of the LED. 10 schematically illustrates the principle of PWM dimming. As can be seen from Fig. 10, during the conduction of the LED, the magnitude of the current flowing through the LED remains unchanged, so that a relatively high luminous efficiency and good luminous quality can be achieved.

As can be seen from the analysis, it is desirable for the LED drive system to utilize PWM dimming and at the same time to ensure effective isolation between the LED device and the high voltage power supply. However, satisfactory solutions are not currently available.

Since DC voltage is required to drive the LED, it is known to those skilled in the art to insulate the LED device from a high voltage power supply using a DC / DC converter. In order to use the DC / DC converter, since the PWM control signal is required to be output by the PWM controller to control the switch of the DC / DC converter, the voltage from the power supply becomes a high frequency pulse, thus driving the LED by the converter. Can be converted to a low voltage. Typically, the frequency of the PWM control signal is on the order of 10 kilohertz (kHz) to one hundred kilohertz.

The inventors recognize that the frequency of the PWM dimming signal used to perform the PWM dimming for the LED is generally within the range of 100 Hz to 1000 Hz, which is much lower than the frequency of the PWM control signal. When the PWM dimming signal is directly modulated with the current PWM control signal, that is, when amplitude modulation is performed on the current PWM control signal by using the PWM dimming signal to generate a new PWM control signal, the dimming signal is applied to the new PWM control signal. Directly carried by the system, the structure of the system can be greatly simplified.

The PWM control signal can be generated by performing amplitude modulation on the current PWM control signal, or can be generated by performing frequency modulation on the PWM dimming signal. In addition, it can be considered that the PWM signal of the present invention is generated directly according to the PWM dimming signal, i.e., the envelope curve of the generated high frequency PWM control signal corresponds to the waveform of the PWM dimming signal.

Thus, in accordance with an embodiment of the present invention, a method for driving an LED is provided. 11 shows a flowchart of a method for driving an LED. As can be seen in the figure, the method comprises the following steps:

S1110: Generating a PWM control signal with a PWM dimming signal. The frequency of the PWM dimming signal is generally in the range of 100 Hz to 1000 Hz. 12 schematically illustrates the generated PWM control signal. As can be seen from the figure, the envelope of the new PWM control signal changes in accordance with the PWM dimming signal. In each non-zero time period of the dimming signal, the original PWM control signal is still included. In other words, amplitude / frequency modulation is performed on the original PWM control signal using the PWM dimming signal, and the frequency of the PWM control signal is not changed.

S1120: controlling the PWM DC / DC converter with a PWM control signal to generate the driving voltage of the LED.

In the method according to the invention, PWM dimming can be used, while effective isolation between the LED device and the high voltage power supply can be ensured.

6th Example

Corresponding to the fifth embodiment, according to the sixth embodiment of the present invention, an LED drive system is provided, and can realize the use of PWM dimming and effective isolation.

13 shows a schematic structural diagram of an LED drive system according to an embodiment of the present invention. As can be seen from FIG. 13, the LED drive system includes: a PWM DC / DC converter 1310, a PWM controller 1320, and a PWM dimming signal generation unit 1330. The PWM dimming signal generation unit 1330 is configured to generate a PWM dimming signal. The PWM controller 1320 is configured to generate a PWM control signal by using a PWM dimming signal. The frequency of the PWM dimming signal here is generally in the range of 100 Hz to 1000 Hz. The PWM DC / DC converter 1310 is configured to generate a driving voltage of the LED according to the PWM control signal.

Preferably, the LED drive system according to the embodiment further comprises a constant current control unit 1340 adapted to ensure that the magnitude of the current flowing through the LED remains constant. The operating principle of the constant current control unit 1340 is that a current flowing through the LED is detected and compared with a predefined value. When the current of the LED is different from the predefined value, a feedback signal is generated in the PWM controller 1320 to adjust the PWM control signal. The mode of operation is familiar to those skilled in the art and will not be shown further herein.

Preferably, the LED drive system according to the embodiment further includes an insulation and feedback unit 1350 configured to input feedback from the constant current control unit 1340 to the PWM controller in an electrically isolated manner. For example, optical coupling can be used to achieve isolation.

In the LED drive system according to the invention, PWM dimming can be used, while effective isolation between the LED device and the high voltage power supply is ensured, ensuring that the system can be easily designed in accordance with safety standards. In addition, since the system has a simple structure, the production cost is greatly reduced, and accurate constant current characteristics can be ensured. Thus, highly accurate requirements regarding the current of the LED can be met.

Finally, because the term "comprising" or any other variation refers to non-exclusive inclusion, a process, method, article, or device that contains a series of elements includes not only these elements but also is not explicitly listed. It should be noted that it includes other elements or further includes unique elements of a process, method, article or device. In addition, when there is no additional restriction, an element defined by the word “comprising” does not exclude that there are other identical elements in a process, method, article or other device that includes the element therein.

Embodiments of the present invention are described in detail in cooperation with the drawings. However, it should be understood that the above-described embodiments are only used to illustrate the present invention, and do not constitute a limitation of the present invention. Various modifications and variations can be made to the above embodiments by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the present invention is defined only by the appended claims and equivalent meanings.

610: dimmer 620: LED driving device

Claims (12)

A method for obtaining a conduction angle of a trailing edge dimmer,
Determining a time t0 when the trailing edge dimmer begins to conduct;
Determining the earliest time point t1 when the deviation from the ideal waveform appears; And
The conduction angle t1-t0 of the trailing edge dimmer based on the earliest time t1 when the deviation from the ideal waveform appears and the time to when the trailing edge dimmer starts to conduct. Steps to determine
Including,
Method for obtaining the conduction angle of the trailing edge dimmer. The method of claim 1,
Determining the earliest point in time when deviation from the ideal waveform appears,
Perform sampling on the output voltage of the trailing edge dimmer, compare the sampled values with the ideal waveform, and exhibit the deviation from the ideal waveform based on the difference between the output voltage and the ideal waveform. Determining the earliest point in time t1 when
Method for obtaining the conduction angle of the trailing edge dimmer. The method according to claim 1 or 2,
In determining the conduction angle of the trailing edge dimmer, an average value of the conduction angles obtained in a plurality of cycles is calculated, and the average value is taken as the obtained conduction angle,
Method for obtaining the conduction angle of the trailing edge dimmer. LED driving method,
Determining a type of dimmer;
When it is determined that the connected dimmer is a leading edge dimmer, obtaining a conduction angle of the leading edge dimmer;
When it is determined that the connected dimmer is a trailing edge dimmer, obtaining a conduction angle of the trailing edge dimmer in a method according to any one of claims 1 to 3; And
Generating a dimming signal according to the obtained conduction angle of the dimmer
Including,
LED driving method. The method of claim 4, wherein
And further comprising an anti-jittering control step after the conduction angle of the dimmer is obtained, wherein in the anti-jittering control step, a change in the conduction angle of the dimmer is detected, and the conduction of the dimmer Only when the change in angle is greater than a certain threshold, the dimming signal is generated according to the changed conduction angle of the dimmer,
LED driving method. The method of claim 4, wherein
Before determining the type of the dimmer, further comprising detecting whether the dimmer is connected,
LED driving method. A conduction angle acquisition device for a trailing edge dimmer 700,
A conduction time determination unit 710, configured to determine a time point t0 when the trailing edge dimmer starts to conduct;
A phase cutting point determining unit 720 configured to determine the earliest time point t1 when a deviation from the ideal waveform appears; And
The conduction angle t1-t0 of the trailing edge dimmer based on the earliest time t1 when the deviation from the ideal waveform appears and the time t0 when the trailing edge dimmer starts to conduct. The conduction angle determination unit 730 configured to determine
Including,
Conduction angle acquisition device for a trailing edge dimmer. The method of claim 7, wherein
The phase cutting point determination unit 720 further includes a sampling device and a comparison device,
The sampling device is configured to perform sampling on an output voltage of the trailing edge dimmer to obtain sampled values, and the comparison device compares the sampled values with an ideal waveform, and the output voltage and the ideal waveform. Configured to determine the earliest time point t1 when a deviation from the ideal waveform appears based on the difference between
Conduction angle acquisition device for a trailing edge dimmer. The method according to claim 7 or 8,
The conduction angle determination unit 730 further comprises an averaging device configured to calculate an average value of the conduction angles obtained in a plurality of cycles, and take the average value as the obtained conduction angle,
Conduction angle acquisition device for a trailing edge dimmer. As an LED drive device 800,
A dimmer type determination unit 820, configured to determine the type of the dimmer;
A conduction angle obtaining device for a leading edge dimmer 830 configured to obtain a conduction angle of the leading edge dimmer when it is determined that the connected dimmer is a leading edge dimmer;
10. The conduction angle for the trailing edge dimmer 700 according to claim 7, configured to obtain the conduction angle of the trailing edge dimmer when it is determined that the connected dimmer is a trailing edge dimmer. An acquisition device; And
A dimming unit 850 configured to generate a dimming signal according to the obtained conduction angle of the dimmer
Including,
LED drive device. The method of claim 10,
An anti-jittering control unit further after the conduction angle acquisition device for the leading edge dimmer 830 and the conduction angle acquisition device for the trailing edge dimmer 700 prior to the dimming unit 850. And the anti-jittering control unit is configured to detect a change in the conduction angle of the dimmer, and only when the change in the conduction angle of the dimmer is greater than a certain threshold, the dimming signal is changed to the changed conduction angle of the dimmer. Generated according to,
LED drive device. The method of claim 10 or 11,
Further comprising a dimmer determining unit 810 before the dimmer type determining unit 820 configured to detect whether the dimmer is connected,
LED drive device.

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